News:




  • December 17, 2018, 03:59:39 AM

Login with username, password and session length

Author Topic: Vortex Generators - Development and Installation.  (Read 14435 times)

Offline PJ Rowland

  • AUS - 29541 AMA - 809970
  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1914
  • Melbourne - AUSTRALIA
Vortex Generators - Development and Installation.
« on: September 01, 2011, 08:04:02 AM »
Vortex Generators & Aerobatics.


P.J Rowland.

I wrote this article for those whom wish to trial something different.

A Micro Vortex Generator

Creates a tiny vortex in the airstream over an airfoil. This vortex energizes the normally stagnant boundary layer of air on the wing's surface. An energized boundary layer is more resistant to flow separation than a stagnant boundary layer. The result is that airflow "sticks" to the wing better, permitting flight at lower airspeeds with improved control authority. Vortex generators delay flow separation and aerodynamic stalling, thereby improving the effectiveness of wings and control surfaces.

Installing 1 pair of VG's top and bottom Inboard and outboard is so easy - its a more effective way to improve the boundary layer compared with traditional techniques such as Wire along the leading edge or highpoint. It works - there is no guess work involved. Run them 20 degree's to the airflow, in a Pigeon toe configuration or.. You can also run them inboards facing 1 direction and outboard facing the opposite direction at the highpoint.  I found more than 1 pair isn’t anymore effective, on the stab isn’t effective at all ( or that I could detect ) I have flow back to back flights with them on and off with measurable tangible results.

Try this experiment, take a glass of water and agitate the water with your hand and time how long it takes for the water to settle. Now circle your finger around like a little whirlpool and measure how long it takes to settle back down... You will find it’s substantially longer. I’m sure there is a scientific equation for this phenomenon however it’s not important for this article.


Agitated water takes between 6 - 10 seconds to settle
Circled whirlpool water takes 15 - 23 seconds to settle.


You are giving the boundary layer a lot more energy to work with compared to normal turbulent airflow of a piece of wire. VG's force the airflow to move down the wing in a spiral fashion, because of the inherent nature of a Vortex form, it lasts longer, moves further down the wing and allows for less flow separation than almost any other single form of boundary layer separation.

I will admit, I don’t work in the aerospace industry - however I have been experimenting with Vortex Generators of this style and reading as much as I can on the subject since 1996. I have also had several discussions with a company whom specialize in the design and application of this technology. That’s 15 years of development, I think it counts for something when you consider how many separate aircraft I've flown them on in countless configurations.

Back in 1996 my initial contacts were made with a company which still exists today - Micro Aerodynamics Inc, whom specialize in the application, design and fit out of this technology. After reading on their website about the technology the following line was a light bulb moment: “They control airflow over the upper surface of the wing by creating vortices that energize the boundary layer. This results in improved performance and control authority at low airspeeds and high angles of attack “



Photo google.com

That was enough for me to start to experiment with the idea – I proceeded to make email conversations with them and discuss theory and application for the use in model aircraft, they were indeed very informative and happy to answer any questions I had at the time. As for design – I haven’t altered the shape too much from their initial plans; the biggest most difficult factor was size.

We used the following basic principles: A Piper Meridian has a wingspan of 575 Inches or approx 43 feet. A normal size stunt plane is also 57 Inch wingspan or there about. A full sized plane Vortex generator measures 1” Long (x) .25 “tall. Using the same scale my Vortex generators would need to 3/32 tall x just over 1/64’ tall... obviously this was not going to be practical.  This has been something that we all struggled with initially, how big do we make them? My initial tests were rather crude compared to the methods I use today. Originally I made them out of thin ply, and they were roughly ˝ Inch long. We made a lot of them initially we put them all span wise, 10 % forward of the leading edge like MircoAero suggested. The distance apart was roughly 3 “ apart in a pigeon toe configuration and we had approximately 18 on each wing 72 in total top and bottom inboard and outboard. (This was new ground for everyone – an aerobatic model aircraft, flying in a circle, with huge power to weight ratio – I often asked if there was a way to calculate a more efficient place to locate them and no one knew, the consensus was to experiment.

The very first flight gave enough improvement to satisfy me that this was a technology worth pursuing. I will admit the performance of my planes at the time was average, I was only 17 years old and we were all learning the ropes about weights and aircraft design.

What benefits I saw from that initial flight remain today – It didn’t improve the sharpness of the corner however it was more stable and more repeatable. I felt I could bang the corner as hard as I liked without fear of having it “slide” down or “slide” out from the initial tracking location. Flying in wind proved a little easier in that I didn’t experience as much drop or rise when flying upwind or downwind. Turbulence was reduced and as a result I always felt more confident flying when conditions were not perfect. The only time it didn’t have any effect was flying in DEAD calm conditions where you would hit your own wake turbulence, this is still an issue with rocking around however we do not experience any “dead” spots or “dead” patches of air were the model all of a sudden looses height. We suspect this is due to there still being enough airflow moving over the wing due to the vortex created, an easier way to think about how this occurs is to visual a bird not moving forward when flying into the wind, it still has enough airflow moving over the wings to remain airborne. I have never lost a model or even come close due to this phenomenon. This is after 15 years of high level competition flying at Nationals, US Nats and World championships. Also in conditions were other fliers have lost models due to these circumstances.

With that initial model success we went on to build a new model in 1997 called “Vortex” this model was designed to be light, all my own numbers 52 Oz Moki .51 power and a flat stab modeled on the Impact however with a swept back hingline.
This model formed the basis for most of my experiments in Vortex generator locations and positions. It was a solid performing model and landed me my first major competition victory.
A short transcript from the article from the contest:
The winning Vortex recorded a clear victory to take the prestigious 35 year old Stunt master’s Trophy – PJs  first big scalp. The Moki 51 powered plane, which has been impressive ever since being finished earlier this year, flew very well throughout the day and finished with a clear margin.
The Vortex has many interesting features with the line-up including: the sparless wing is heavily double tapered, the leading edge has vortex generators top and bottom for the full span, and the flaps incorporate experimental angle countering "flapettes". Total weight is 52 ounces





The model ended up with 6 pairs (6/48 configuration or 48 VG’s in total ) top and bottom, down from the initial 8/72 configuration. The size also reduced slightly but was still larger than I use today – handling and installation was always an issue.
This came about most from my frustration at knocking them off, and that I was sick of making so many. I found out from the early flights that even when several were knocked off due to handling the performance remained. We then continued over time reducing them. The 1997 Vortex took the most of the experimenting, it was very easy down at the field, - a bottle of CA and some tweezers I could have back to back flights with no more than 10 minutes in between of changing locations.
I tried every combination you could imagine on this model – On the wing, in the middle of the wing, near the flaps, on the Stab, near the elevators, on the fuse, on the fit, on the tips, just to see what was effective, and what wasn’t.
Needless to say no other location other than near the highpoint had any effect. I have seen them on elevators of full sized models – they are meant to improve control authority, however in our experiments I could not notice any improvement in that area.  If I did not see a repeatable, tangible improvement that I could see with back to back flights I did not proceed.

You might also note – that model also featured the “ Flaps devices” or as I refer to them the “ Rush style Boost Tabs” I started experimenting with that concept also on that model. I have also used these ever since, developing that over the same course of time. I will not talk about that – I think Howard Rush (USA) has covered that in enough detail.


Over the course of that models life cycle ( 2 Nats and approx 2000 flights ) I found the best location was just near the Highpoint, which is further back than the initial 10% back that I was recommended. Part of this was to help people who were launching the model not to get caught in the VG’s but I did find it marginally better, further back. One of the things I did do was create more drag, which in turn required more power, or pitch to fly at the same lap times. The initial engine of Moki 51 Simply didn’t have enough juice for my liking, it was difficult to achieve a nice 2 / 4 break with running it as hard as I required. Also I was running a thick Impact style wing. The solution was temporarily solved in the next model, make it smaller.

In 1998 we designed the Vortex 2 which was a 20% smaller version of the 1997 Vortex 1 – however it never performed to my expectations. We made it smaller everywhere in an attempt to increase the power to weight ration - I suspect the tail was too small it was also a Flat stab – It flew for a half season and was never a brilliant model, the VG’s were altered on this model quite a lot but never got the model itself right.

In 1999 we designed Vortex 3 which was the first of my planes to be painted in a Tiger paint scheme thus was know to all as “The Tiger”  It was a 10% smaller version of the 1997 model however featured a much larger tail in area. Wingspan of 55 “ with a Trivial pursuit 1994 Stab Air foiled. From day 1 this was incredible – it was clearly the best model I had to date. I never located the exact reason why V2 flew so poorly, when in terms of numbers it was so close to the Tiger, however we just changed the Stab. I have always wanted to cut the Stab out of V2 and replace it with the Stab from that 1st tiger just to see if that was the cause.

That model again had reduced Vg’s in terms of numbers and placement. This model went down to 4 pairs ( 4/32 combination ) This was also the first model that I moved them away from the fuse, completely out of the prop wash ( 10 Inches out from the Root or fuse side walls ) I did this partly in my belief that the Stab was somehow getting turbulent air from the wing and the VG’s perhaps this was the reason the other flew so poorly. It was also easier for people to hold without having to worry about knocking them off.
This model also ran my 1st rear exhaust engine the Stalker .61 – trying to find more power for the increased drag, it was eventually upgraded to the Stalker .61 long stroke and still to this day I consider it one of my best planes.  I won a couple of State Championships with it, and placing 4th at the 2002 Nats.

That model had close to 2500 flights and was brilliant. I loaned it fellow flier and it met its fate during an overhead 8 when the engine quit. Only thing that remained was the Stab ( He was practicing multiple overhead 8’s with it ) I regret loosing that model, because I didn’t have any definitive numbers written down about its design. The next model was a different design all together. I would like to attempt to recreate that model with photos and the Stab I have left.

  
Over the course of that models life, the Vortex generators got more and more knocked off, without replacements – I found as little as 2 pairs ( 16 in total ) still yielded great results. So out of a need to speed up the process of installing them, I settled on 2 pairs for each wing ( 2 / 16 )  the installation changed also over time, making them smaller, spacing them out. I always liked 6 inches in from the Fuse side wall for the 1st pair and 6 inches in from the tips for the second pair. I remained with that configuration for a number of planes and a number or years, refining how I would build them. In the end I found the smallest I could go was dictated by my ability to hold them in the tweezers. We made them out of carbon fiber and still CA them to the wing.

Over the last 4 years I have experimented further with reduction and my current configuration I believe is the best. I now only run 1 pair top and bottom ( 1 / 8 ) configuration. The location of the Vortex generators is usually 6 – 8 inches in from the fuse wall and located at the highpoint.

I have flow the same model back to back, with them installed, and then removed – its tangible, repeatable, definitive difference in how the model flies. I wouldn’t say it alters the design at all; it’s just more reliable in the corner. We also find speed control is enhanced due to the excess controlled induced drag. I find landings are easier because the model does not “fall” out of the sky downwind, or do anything of the sort.



Again I say its not for everyone – I think of installing Vortex Generators along the same line of thinking as sealing the Hinge lines – its an improvement that is measurable and beneficial. A lot of people think it’s only for “overweight aircraft” and to a certain degree that’s correct – it will make a 70oz model less inclined to drop out of a corner.
 
If you have a light plane I don’t think it will help with reducing stall speeds. However most of my current crop of planes are considered "comp spec weights 59 – 64 oz range" I still find I prefer the feel of being able to easily load the engine and to a certain degree control wingtip rocking due to turbulence in windy conditions also control aircraft speed - e.g. windup. Obviously a good pipe engine or electric doesn’t affect this part.



How to Install Vortex Generators:

VG Specs ; Inches
Material : .02 Uni Direction carbon laminate.

Thickness : .02”
Height : .14”
Length : .43”





Making them isn’t difficult.  Use .02 Unidirectional carbon laminates from APC Composites. First step is to start cutting them to length.  You can make the carbon strip any length you want.



Here we have made a single strip that is taller than it will end up – the reason for this is to make it easier to sand and handle, you want to cut them down last.





These are cut into basic shapes that are close to the same length of .43 (little over 1 cm) makes for consistent shapes.

Hand sand the front leading edge shape of the generator. I do this with 120 Grit sandpaper and shape it until its round and they are all accurate / uniform.



Check the height and trim to match.
Once I have the shape defined – I trim it to the exact height required of .14” this is checked with a vernier. I either sand this or trim it with a sharp blade. You can see below how the 2 are different.



Try to get the heights as accurate as possible, double check each one before you move onto the next.  The heights are important for a consistent Vortex, the last thing you want is differences in Vortex energy moving down the wing.



Repeat until you have enough for your project & spares. My latest configuration and the one I suggest people start with are 2 / 8. ( 2 on each surface for a total of 8 )



The critical part of any stunt ship is always alignment. Installing Vortex generators is no exception. I usually do this task at the end of the build, after buffing is completed. Its impossible to buff or sand out a model with the VG’s installed before, so do not attempt to fix them before. Simple cleaning and waxing can be done around it after for appearance judging, just be careful.

Place a centre line down the fuselage, this will help to get accurate measurements for the placement of the VG’s on both sections of the wings.



I make up templates for installing the generators the one template is used for the entire model – it sets the angles, the distance apart, the distance from the leading edge.

For the latest group of models the distance is as follows: the centre line of the template is 7 ˝ inches from the fuselage centre line. The Vortex generators are in total – 3 Inches apart from each other – Centre line of the template mark outward 1 ˝ inches – this will be where your Vortex generators start.
Make up this template it helps for alignment and correct placement.

The template is critical to get correct. I make the generators anywhere between 17 degrees and 20 degrees – the more angle the more drag. How to align them has always been a concern – Do I line it up with the leading edge, or do I line it up 90 degrees to the airflow. I have always felt aligning it to the airflow was correct – although I have done both with little measurable differences.

As you can see below the template shows the correct angle. The sweep angle of the leading edge of this specific aircraft is approximately 2 degrees. I factor that into the template so when it’s sitting on the wing – the Generators are at 90 degree’s to the airflow.



The template is symmetrical – The lines on the plane below are used for alignment of the template to a marker: this is to make sure we get them exactly in the same spot in all 4 locations. Note – I always join the bottom and top tape lines together to make sure they are accurate.






Tape the template to the guide lines.  Here you will note the front of the template lines up with the leading edge. Remember to take the sweep angle into account – its usually no more than 2 degree’s for a normal tapered wing. – When you use it on the other side, simply flip the template over and use the reverse for the opposite side.




I use a little pool of CA and dip the end of the generator into it – using tweezers carefully apply it to the front of the template. Once the CA has gone off – I will then add 1 small drop of medium CA to the carbon, this gives it some strength and resistance to being knocked off. If you simple leave the tiny amount of CA on the bottom they are more prone to being removed.





This is the view from the front – here you can see they are perfectly aligned to form a very small X. Even at 20 degree’s its very minor but very effective.



Here is another angle up close of them completed. I intentionally paint the leading edge up that far – in part to hide the VG.





Here is the completed plane with the Vortex Generators installed. Like sealing hinge lines if you do it correctly, it’s a discrete installation.



Like many things we do in this event it’s about diversity, trial and error – what works for one person might not work for someone else. Pipe or no pipe? Electric or IC ? Nitro or FAI ? Solids or Braided ?
The best thing we can do is share information and hopefully pick up a few hints and tips along the way. I will not build a model without Vortex generator technology included, no different to sealing my hinge lines or running asymmetry on the wing. There have been many designs past and present that achieve success in their own way – Spend 2 hours one day on an older model go through the process of installing Vortex Generators as shown and make your own assessments.

If you like it build it into the next model – Good luck and keep flying and developing.

P.J Rowland.



If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” - Bruce Lee.

...

I Yearn for a world where chickens can cross the road without having their motives questioned.


Offline Shultzie

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3490
  • Don Shultz "1969 Nats Sting Ray"
Re: Vortex Generators - Development and Installation.
« Reply #1 on: September 01, 2011, 10:52:34 AM »
WOW!
Beautiful CLPA model..."FAB PAINT SCHEME" and FOOD FOR THOUGHT! VORTEX GENERATORS CONCEPT IDEAS FOR CLPA MODELS!

(Brings back so many memories  ( both GOOD AND BAD) during my long gone Boeing  Phantom Works daze days n nights performing all kinds of  Wind tunnel model study projects utilizing adjustable vortex Generators that  automatically deployed with the variable speeds of the air over the surfaces of the model....UNTIL THEIR  NASA STUDY GRANT $$$ RAN OUT!

Not only these small generators were made to change angles by the pilot, or also AUTOMATICALLY IN FLIGHT with the wind flow...but also could be extended or retraced.

This was perhaps the most challenging model building and wind tunnel project that I had ever taken part in during the almost 30 years at Boeing.
What a night mare building project...making a reliable set of servo run generators...that also could be rotated and well as extended in and out of the wing surface. Sadly this project was scrubbed and later after I left that project...just before retiring in 2004, a study was being conducted on not only the adjustable generators but also the the actual "saw tooth" trailing edges on the new generation  Jet Engines.

Hey you Aerodynamical Engineers...IF YOU ARE LURKING, sounds like a great place to jump in here and share your pain and gain with this subject of Vortex toys of flight design as the beat goes on and on!
All in all our greatest vortex teacher of flight is still this (attached photo) creature of flight..IF ONLY HE COULD TALK!


Don Shultz

Offline Jeff Traxler

  • T-Bone
  • 2013 Supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 651
Re: Vortex Generators - Development and Installation.
« Reply #2 on: September 01, 2011, 11:00:25 AM »
PJ,
   Thanx for sharing the developement and installation with us all.I had a nice chat with you and your dad about these on the L-pad and I have been meaning to send a PM inquiring about more info concerning just what you have posted.I think many ideas can be borrowed from full size aircraft and vice-versa.Mr. Rutan turned the homebuilt world upside down with his composit building techniques and now many airliners are using composit components.I think composit stunters will be commonplace soon just like they are in the homebuilt world.New ideas must be tried before they can fail and I see these on my new composit electric stunter.Remember that the world was flat before Columbus took a little boat ride with an idea and some courage to try what was out of the norm.Aerodynamics are a large part of the modern stunt world and the vortex generators make perfectly good aerodynamic sense.I can't wait to try some out.The worst that can happen is I will fall off the edge of the world LL~ LL~ LL~.
                                                                                      Thanx again PJ,Jeff Traxler
If you wanna sing the blues(Fly Stunt) you gotta pay your dues and "I know it don't come easy"

Offline Michael Boucher

  • 2015
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 516
Re: Vortex Generators - Development and Installation.
« Reply #3 on: September 01, 2011, 03:27:24 PM »
I remember Vortex Generators being used on the Boeing 707.  ;)
AMA 59633

Offline PJ Rowland

  • AUS - 29541 AMA - 809970
  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1914
  • Melbourne - AUSTRALIA
Re: Vortex Generators - Development and Installation.
« Reply #4 on: September 01, 2011, 03:59:57 PM »
The use of Vortex generators in the real aviation world is not in question, implimenting them for use in CLPA is. - The model pictured is my new ( finished earlier in the year ) Ares.

I wanted to write something definitive, so for those who wish to try the technology and see what improvements it gives them ,could and would do it properly or atleast benifit from my years of development with it.  It would be nice to get feedback from others who have tried this technique. Just remember it wont radically alter anything - its just airflow control. Think of it like getting new tyres on your car for better grip, most day to day driving you wont notice it, your 20 year old car will not suddenly turn into a ferrari it just helps you when you get in trouble, or you want to start pushing it.

It wont make your ship turn faster - however you can.. to a certain degree gear your controls to bang the corner harder.. without fear of wing wobbles or so forth. However accuracy and execution of the corner is still important to get right.


I like how easily you can land a model - You need to really fly it down - Whereas without them, you tend to whip it a little more and let the plane and gravity do the work.
If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” - Bruce Lee.

...

I Yearn for a world where chickens can cross the road without having their motives questioned.

Offline Douglas Ames

  • 2014 Supporters
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1299
Re: Vortex Generators - Development and Installation.
« Reply #5 on: September 01, 2011, 04:14:37 PM »
...just before retiring in 2004, a study was being conducted on not only the adjustable generators but also the the actual "saw tooth" trailing edges on the new generation  Jet Engines.

-The 787 has these. I was under the impression they were for sound suppression for the fan air exit.

-Neat concept but as you scale things down the air molecules don't change in mass or density, which is why our airfoils are proportionally bigger than full scale. (correct me if I'm wrong on this) I think your on the right track. I'd keep experimenting!

AMA 656546

If you do a little bit every day it will get done, or you can do it tomorrow.

Offline Steve Helmick

  • AMA Member and supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 8424
Re: Vortex Generators - Development and Installation.
« Reply #6 on: September 01, 2011, 07:18:30 PM »
There's a bunch of different types of turbulators used on Free Flights, and frankly, I'd suggest starting there. The RN are at least closer than those of a 787. Most all will increase drag (maybe not what you want with an electron burner), but like PJ says, there are other benefits to be gained, like corners and landings.  H^^ Steve
In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.

In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

"Be polite, be professional, but have a plan to kill everybody you meet." General Mattis.

Offline PJ Rowland

  • AUS - 29541 AMA - 809970
  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1914
  • Melbourne - AUSTRALIA
Re: Vortex Generators - Development and Installation.
« Reply #7 on: September 01, 2011, 08:18:15 PM »
Turbulators for use in free flight are trying to acheive something slightly different. - They are operating at completely different airspeeds, completely different weights and vastly different airfoil sections.  The benefits are that the turbulators smooth out a gliders recovery when nearly stalling in very turbulent air such as found in some thermal conditions also as part of the trimming aspect - the principle to be able to trim a glider to fly slightly more nose up without stalling.

Please try to keep in mind, this is not a new idea; I should have added to my article that over the past 15 years I've been developing it, that has been combined with hundreds of accumulated hours of research into all sorts of airflow separation devices in partnership with on-field testing, modern aerobatic ship design and an experienced stunt pilot. I have also had several email and actual conversations with top level free flight guys ( Remember the model aircraft industry isnt that big ! and I meet alot of modellers from around the traps )

I don't dismiss the idea of " turbulators " or the use of wire - just as part of my experiments we did try several of these concepts with insignifigant gains in performance when directly compared to the technolgy of Vortex Generators, how it relates to improving performance specifically to Control line aerobatics.



« Last Edit: September 01, 2011, 08:44:51 PM by PJ Rowland »
If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” - Bruce Lee.

...

I Yearn for a world where chickens can cross the road without having their motives questioned.

Offline John Miller

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1594
Re: Vortex Generators - Development and Installation.
« Reply #8 on: September 01, 2011, 08:52:45 PM »
Thanks for posting your information on vortex generators for models PJ. It inspired me to look further into the subject, and I decided to install them on the 2 Bits Bipe to see if it helped with the last square corner. It seemed a perfect little test as I'm getting ready to build a new set of wings with a total of about 100 sq. inches more area to try and get a better wing loading.

I'll try and fly the plane this weekend and see what difference there is.

Getting a line on life. AMA 1601

Offline PJ Rowland

  • AUS - 29541 AMA - 809970
  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1914
  • Melbourne - AUSTRALIA
Re: Vortex Generators - Development and Installation.
« Reply #9 on: September 01, 2011, 09:04:30 PM »
Good work John !

Id say.. Combined with your new engine - and the addition of the VG's I'd be surprised if that won't help. I will guarantee you will notice improved performance even on the lower powered engine.

In fact I have never flown a Bipe, and run Dual Generators ; let us all know what you find - looking at the photos the installation seems perfect - Are they on both wings.. top and bottom? you should have - 16 in total. a 2 x 4 / 16 configuration..

Goodluck

It will help with overweight models for sure .. my bomber was 120 +oz and I've had other models after rebuilds and so forth that move out toward 70 oz range.. The Gieseke nobler I flew at the US Nats was 53 oz this is several oz heavier than most considered acceptable for an aircraft of that size - mostly due to the .61 in the nose ; VG installed off the board & Top 20 Open.
« Last Edit: September 01, 2011, 09:41:29 PM by PJ Rowland »
If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” - Bruce Lee.

...

I Yearn for a world where chickens can cross the road without having their motives questioned.

Offline Shultzie

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3490
  • Don Shultz "1969 Nats Sting Ray"
Re: Vortex Generators - Development and Installation.
« Reply #10 on: September 01, 2011, 09:57:17 PM »
-The 787 has these. I was under the impression they were for sound suppression for the fan air exit.

-Neat concept but as you scale things down the air molecules don't change in mass or density, which is why our airfoils are proportionally bigger than full scale. (correct me if I'm wrong on this) I think your on the right track. I'd keep experimenting!



Sound suppression for the air exit..is very true and was a main concept.. however next door at the Acoustical Lab and Chambers...not only did the "sawtooth TE's OF THE NACELLES work to quiet the sound...surprising to the test director of flight test...
it was noted that it also reduced an additional reduction in vibration, which aided also cleaned up the air flow which in turn reduced drag.

"TRIP STRIPS" WIRES in front of the leading edges of wings WERE ALSO EXTENSIVELY TESTED TO IMPROVE AIR FLOW and reduce parasitic' airflow airfoil drag.
Again..
I worked as a model maker tech aid for these Engineers...and as you can "PLANE PLAIN AS DAY"...from my unschooled aerodymacial skill.....needs to have some of our best Boeing Aero Engineers to step in here on your amazingly well done article about utilizing vortex generators for CLPA models?

HEY GARY LETSINGER...IF YOU ARE LURKING!!!  :! y1TIME TO STEP IN HERE AND GIVE US MORE INFO ABOUT THIS SUBJECT THAT IS WAAAAAAAAAAAAY ABOVE AND BEYOND OUR 75 FEET OF FLYING LINES? LL~

Again OUTSTANDING PROJECT OF YOURS...SO BEAUTIFULLY WRITTEN AND ILLUSTRATED!
THANKS FOR SHARING THIS WITH SO MANY OF US NERD-NEAR DE'WELL CLPA GRUNTSTERS.
« Last Edit: September 02, 2011, 10:28:20 AM by Shultzie »
Don Shultz

Offline John Miller

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1594
Re: Vortex Generators - Development and Installation.
« Reply #11 on: September 01, 2011, 10:34:14 PM »

In fact I have never flown a Bipe, and run Dual Generators ; let us all know what you find - looking at the photos the installation seems perfect - Are they on both wings.. top and bottom? you should have - 16 in total. a 2 x 4 / 16 configuration..

Goodluck

It will help with overweight models for sure .. my bomber was 120 +oz and I've had other models after rebuilds and so forth that move out toward 70 oz range.. The Gieseke nobler I flew at the US Nats was 53 oz this is several oz heavier than most considered acceptable for an aircraft of that size - mostly due to the .61 in the nose ; VG installed off the board & Top 20 Open.


I was pleasantly suprized at how easy it was to install the VGs on the Bipe. I did use 1/64" ply rather than CF, but that shouldn't stop them from working. I do have them on the top, and bottom of each wing. I printed up a guide from the CAD file to get the alignment as close as possible.

I may try and fly the plane in the morning if the guys are still in town. They may be taking off for the Denver Contest early. 

I'll post my impressions after I do fly it though. H^^
Getting a line on life. AMA 1601

Offline PJ Rowland

  • AUS - 29541 AMA - 809970
  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1914
  • Melbourne - AUSTRALIA
Re: Vortex Generators - Development and Installation.
« Reply #12 on: September 01, 2011, 11:42:49 PM »
1/64 will be fine. I have used ply in the past. I just prefer sanding carbon fiber and find it adhereds to the paintwork much better - for testing purposes it will do the job just as well.

Nice install.
If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” - Bruce Lee.

...

I Yearn for a world where chickens can cross the road without having their motives questioned.

Offline Doug Moon

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1861
Re: Vortex Generators - Development and Installation.
« Reply #13 on: September 02, 2011, 01:00:13 PM »
I have been away for 2 days.  I just saw this.  Thanks for posting all of this great info.  I havent been able to read it but I will get to this weekend.

Thanks

Doug
Doug Moon
AMA 496454
Dougmoon12@yahoo.com

Offline John Miller

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1594
Re: Vortex Generators - Development and Installation.
« Reply #14 on: September 02, 2011, 03:43:16 PM »
Well, I have good news, and not so good news regarding the VGs on the bipe.

First, the good news is they did affect the power off glide, and I did seem to have to fly the plane down to a landing. I noticed no additional drag being introduced, at least, I couldn't feel any differences.

The bad news is that on this day, at this temperature, (85degrees) and this altitude, (4600' ASL) The plane still stalls on the last turn of the square. I've one more item to try, before I give up on this as a solution, and that's adjusting the flap-elevator ratio to 1-1.

If that doesn't work, then I'll have to try more wing area.

Sunday, we're scheduled to fly again, and I'll try with the ratio changed.  H^^
Getting a line on life. AMA 1601

Offline PJ Rowland

  • AUS - 29541 AMA - 809970
  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1914
  • Melbourne - AUSTRALIA
Re: Vortex Generators - Development and Installation.
« Reply #15 on: September 02, 2011, 04:22:30 PM »
Based on that ; Id be inclined to add another set 6 " in from the Tips.  

That was how the bomber was flown - as I mentioned in the article I ran the dual sets for a number of years. I would try that if you have time. - Same install just out 6 " in from the tips.

A few things need to kept in mind - VG technology is not a magic bandaid to any fundamental issues with aerodynamics - the basis of the article and my exposure to the development of the technology has been specifically in CLAPA and the associated models.

At any stage I could take them off and still be competitve. However its about finite improvements. Look at the guys who trim out models at the pointy end of the results..- altering or changing something 1/64 of an Inch - to get that last little ounce of performance out their package. Moving up and down in pitch .01 increments.


John : You noticed improved landing power off glide - which indicated to me that you have improved the effectivness of the airfoil. ( This was one area I notice an improvement also - keep in mind landings are worth as much as a square 8.. )



« Last Edit: September 02, 2011, 05:18:35 PM by PJ Rowland »
If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” - Bruce Lee.

...

I Yearn for a world where chickens can cross the road without having their motives questioned.

Offline John Miller

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1594
Re: Vortex Generators - Development and Installation.
« Reply #16 on: September 02, 2011, 05:42:43 PM »
Yes, I was considering adding an additional set of VGs further out the wing. It won't hurt to try that that's for sure. The plane seems to fly rather decently except where the last corner of the square is concerned. Being overweight at 72 oz's is the main reason it seems.

So, my intention is to add additional VGs as you sugge4sted, and after trying that, if there's still a problem, I'll crank in more flap by adjusting the ratio to 1-1.

I'm looking forward to Sunday. y1
Getting a line on life. AMA 1601

Offline Steve Helmick

  • AMA Member and supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 8424
Re: Vortex Generators - Development and Installation.
« Reply #17 on: September 02, 2011, 06:23:45 PM »
John, I wish you had started out with 1:1 flap/elev. ratio. I am sure you will notice quite an improvement, but you will probably still wish the plane was 10 oz lighter. It sounds like you have a Stalker .81 installed already? Between that and the control ratio change and sorting out props and the VG's, it seems you're changing a tremendous number of things at the same time.

When I just changed the control ratio from about .75/1, I could not believe how different the model responded. An inside loop increased in tightness and ended up being pretty much a "figure 9", but with the entry at the lower tail and the exit at about 45 degrees. So be careful! I had to reduce the handle spacing a bunch to be able to fly it at all, then gradually spread the spacing prior to flying in successive flying sessions, until I was out at about 3.25".

PJ...In one of your posts, you wrote:  "I should have added to my article that over the past 15 years I've been developing it, that has been combined with hundreds of accumulated hours of research into all sorts of airflow separation devices..."   Surely, you don't mean that turbulators or VG's are airflow separation devices. They should be creating turbulation by "tripping" the air, to maintain attachment. As for the little fence item, it seems more practical to make V-shaped (cut from CF Angle) or semicircular shape (cut out of a CF tube), which would be much easier to keep attached, and also would not cause spanwise flow, but a widening area of airflow firmly attached to the surface. I would ask Schultzie and Gary Letsinger if Boeing tried different VG designs, and how each worked. Gary's a sharp cookie, so if you get some input from him, it's sure worth a try.   H^^ Steve
In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.

In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

"Be polite, be professional, but have a plan to kill everybody you meet." General Mattis.

Offline Steve Hines

  • 2018 Supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 428
Re: Vortex Generators - Development and Installation.
« Reply #18 on: September 02, 2011, 06:54:22 PM »
I dont know alot about this, but with plane going in a circle should the Vg be on some kind of a angle.

Offline PJ Rowland

  • AUS - 29541 AMA - 809970
  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1914
  • Melbourne - AUSTRALIA
Re: Vortex Generators - Development and Installation.
« Reply #19 on: September 02, 2011, 07:18:07 PM »
Steve : The wording of " airflow seperation devices" was probably not accurate from a technical standpoint.  Boundary layer manipulation . I think I explained the principle well enough.

As for the little fence item, it seems more practical to make V-shaped (cut from CF Angle) or semicircular shape (cut out of a CF tube), which would be much easier to keep attached, and also would not cause spanwise flow, but a widening area of airflow firmly attached to the surface. I would ask Schultzie and Gary Letsinger if Boeing tried different VG designs, and how each worked. Gary's a sharp cookie, so if you get some input from him, it's sure worth a try.


Steve; Please remember what I mentioned about how this was initially developed - I worked closely with a company who specialize in the manufacture, design and application of Vortex Generators for real use in the aviation industry. Part of the problem is no-one has done any work on how it directly relates to CLAPA. I was inspired by the development work of AL Rabe in his airfoil testing and getting something more effictive for CL Aerobatics. Theory is one thing, Thousands of test flights over many years documenting effects and changes on field in the heat of top level stunt competition is another.


Steve Hines: With the general idea you keep everything square - engine thrust, offset rudder - I prefer to run them 90degrees to the airflow. Playing around with the angles might prove an interesting interllectual exercise, but Its easier just to put them straight.



Another analogy that can be drawn is Stab plates.. I have spoke to fliers who have used them - I know the Moon brothers swear by them - obviously Bob Gieseke is one of the more famous people to fly with them. Again its not for everyone - Im not shoving this down anyone's throat. I simply offer up my findings to the stunt community - those whom wish to test it, have very little to loose.



Sealing hinge lines ? How accepted is that as a full sized aero application? CLAPA its important but the model isnt unflyable without them. Its something you do if you want to extract the most out of your Stunter.


If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” - Bruce Lee.

...

I Yearn for a world where chickens can cross the road without having their motives questioned.

Offline John Miller

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1594
Re: Vortex Generators - Development and Installation.
« Reply #20 on: September 04, 2011, 12:14:46 PM »
Taking PJ's suggestion to add 16 more VGs, 6 inches in from the tips, and dialing in a bit more flap, I can say that the stall on the last corner of the square is now gone. I am not too sure whether it is from a combination of affects, or more simply, one or the other, but it's sure nice to see the bipe go cleanly around that last corner.

I'm closing in on getting the wings level in level flight. It seems that the effects from the two wings double up, and if I tweak one flap, I then have to adjust the coupled flap as well. I'm learning as I go on this design.

Still showing a great power off glide, nice round corners that track with each other well, and now nice square corners. As soon as I figure the right combinationof vertical CG adjustment, and flap tweaking to get the wings level both upright, and inverted, I should be ready to fly a pattern.

I've noticed what seems an improvement in the planes ability to track with a bit of turbulence. The wings don't seem to be moving up and down nearly as much as before.

Further flights will show me if it's all in my imagination, or something real to consider. H^^
« Last Edit: September 04, 2011, 04:48:14 PM by John Miller »
Getting a line on life. AMA 1601

Offline PJ Rowland

  • AUS - 29541 AMA - 809970
  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1914
  • Melbourne - AUSTRALIA
Re: Vortex Generators - Development and Installation.
« Reply #21 on: September 04, 2011, 03:59:00 PM »
Hi John.

This news is great to hear.  What you are describing is exactly what I find in flight. Its not your imagination about the improvements.

I suggested another Pair at the tips - which would have been only an extra 8 in total - Due to this being a Bi-plane he required twice as many (16)

I generally dont have problems with the weights of the models - So, althought some ( such as in your case ) will get benifits in performance from adding VG Technology to make a model that suffers from poor wing loading more usable. Adding only 1 set like my article suggests will show all of the above improvments anyway.

Adding in the 2nd pair was going to do the trick for your case..

The improvements you describe are the same for what I use it for:

  • Improved tracking in all round manouvers
  • More stability in turbulent conditions
  • Improved performance in High load corner situations
  • Power off glide performance

Part of the reason I only fly with 1 pair is to get all of these benifits without the addition of too much engine load or to much extra drag. However I have found running 2 pairs to aid more heavy models -the extra pair is not required if your model goes through the pattern normally.

John - the other thing you can do - if your unsure if its its your "imagination" or a combination of thigns.. .. : get it trimmed and setup the way you way - then remove all the Vortex generators and fly it !

I've done this on a few occasions - Got it going the way I want then remove all the VG's - I can assure you its not your imagination...


Im waiting on Doug Moon to give it a go next...
If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” - Bruce Lee.

...

I Yearn for a world where chickens can cross the road without having their motives questioned.

Offline Matt Colan

  • N-756355
  • AMA Member
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3046
Re: Vortex Generators - Development and Installation.
« Reply #22 on: September 04, 2011, 07:55:37 PM »
After reading all this with great interest, I now want to give these a try. I'll have to wait until after the team trials, but I have the perfect plane to try these on, my Oriental Plus, which suffers from being over weight.

PJ, I'll let you know how that goes once I get around to trying it, and I would be like John and using 1/64 plywood instead of carbon fiber.  H^^
Matt Colan

Offline PJ Rowland

  • AUS - 29541 AMA - 809970
  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1914
  • Melbourne - AUSTRALIA
Re: Vortex Generators - Development and Installation.
« Reply #23 on: September 04, 2011, 08:37:23 PM »
Dont think of it so much as a means to make a heavy weight model perform well.. Thats never ideal no matter what. Albeit we have all built models that are heavier.

Again - Like John - Id suggest you start with 1 par as per above, if you still have issues with performance add the second pair in there. - Just remember the ideal usage is to improve model tracking, exit corners, overall stability in turbulence - however on a Comp spec Sub 63 Oz model thats already in great condition - It will give you another few percent of improvement.

Let us know your findings also - Im pleased people are willing to try it.

Rememeber there are always other ways to do things - The chinese for example dont seal the hingelines infact run larger gaps that most novice fliers have - Its not what Id recommend but they make it work.......... somehow...



Goodluck to all at T.T. Wish I could be there.
If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” - Bruce Lee.

...

I Yearn for a world where chickens can cross the road without having their motives questioned.

Offline Matt Colan

  • N-756355
  • AMA Member
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3046
Re: Vortex Generators - Development and Installation.
« Reply #24 on: September 04, 2011, 09:00:25 PM »
Dont think of it so much as a means to make a heavy weight model perform well.. Thats never ideal no matter what. Albeit we have all built models that are heavier.

Again - Like John - Id suggest you start with 1 par as per above, if you still have issues with performance add the second pair in there. - Just remember the ideal usage is to improve model tracking, exit corners, overall stability in turbulence - however on a Comp spec Sub 63 Oz model thats already in great condition - It will give you another few percent of improvement.

Let us know your findings also - Im pleased people are willing to try it.

Rememeber there are always other ways to do things - The chinese for example dont seal the hingelines infact run larger gaps that most novice fliers have - Its not what Id recommend but they make it work.......... somehow...



Goodluck to all at T.T. Wish I could be there.


The Oriental Plus does have an extreme problem when it comes to turbulence. Even just a moderate amount, where any other airplane I have I can get it through without a problem, this plane is almost unflyable. This also pops out of some corners, and I have to concentrate on the right amount of input.

I'll spend some more time with it, and see what the VG's do to it.

Edit: I would try it on the TP, just to see what happens, but I don't have a decent motor anymore. after the team trials, I'll get it fixed
Matt Colan

Offline Doug Moon

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1861
Re: Vortex Generators - Development and Installation.
« Reply #25 on: September 09, 2011, 09:09:59 PM »
I am working on it.  We are finally getting some good weather.  I should be able to try this soon.

Thanks for posting all that info.  I have read about these for years and from what I have seen and read your shape appears to be exactly what I would have come up with.  The TE of the VG is really what sets the "swirl" or vortex.  The shape you are using is just right for that purpose. 

These things work very differently than "trippers" or an attached wire type device.  I am certain I can gain from them as it has always been my view that stunt should be flown as slow as possible.  For me I can only get more and more precise the slower I go.

Thanks again and I will let you know what i find.

Doug Moon
AMA 496454
Dougmoon12@yahoo.com

Offline Howard Rush

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6332
Re: Vortex Generators - Development and Installation.
« Reply #26 on: September 09, 2011, 10:47:15 PM »
Turbulators for use in free flight are trying to acheive something slightly different.

Yep.  "Turbulators" are probably there to trip the boundary layer from laminar to turbulent.  I wouldn't think you'd want that, although Brett says it helps.  VGs bring fast air down next to the wing surface.  It's a different effect.  
The Jive Combat Team
Making combat and stunt great again

Offline Howard Rush

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6332
Re: Vortex Generators - Development and Installation.
« Reply #27 on: September 09, 2011, 11:02:18 PM »
I haven’t altered the shape too much from their initial plans; the biggest most difficult factor was size.

We used the following basic principles: A Piper Meridian has a wingspan of 575 Inches or approx 43 feet. A normal size stunt plane is also 57 Inch wingspan or there about. A full sized plane Vortex generator measures 1” Long (x) .25 “tall. Using the same scale my Vortex generators would need to 3/32 tall x just over 1/64’ tall... obviously this was not going to be practical.  This has been something that we all struggled with initially, how big do we make them? My initial tests were rather crude compared to the methods I use today. Originally I made them out of thin ply, and they were roughly ˝ Inch long.

The boundary layer thickness doesn't scale proportional to the airplane size, so you did the right thing by making them bigger.

We made a lot of them initially we put them all span wise, 10 % forward of the leading edge like MircoAero suggested.

You mean 10% aft?  The Micro guys must have read the same 1950 NACA report that I did.  I was at NASA Langley at the time: 1975.  I put VGs at 10% chord of an F2D plane.  About all it did was to add drag.  I won the Nats that year with that airplane, but without the VGs. 
The Jive Combat Team
Making combat and stunt great again

Offline Allan Perret

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1924
  • Proverbs
Re: Vortex Generators - Development and Installation.
« Reply #28 on: September 10, 2011, 07:01:48 AM »
Hey PJ:
 
Looking at that front view of your VG installation,  the gear strut looks to be right between the pair on the bottom of wing. 
I would think that the strut would reduce the effectiveness of the bottom pair,  or at least cause an imbalance of the VG effectiveness from top to bottom wing.   

Have you been able to detect any difference of the VG's relative to inside and outside turns ?

Have you installed VG's to any plane with fuse mounted gear ?    If so how did they compare to the wing mounted gear planes ?
Allan Perret
AMA 302406
Slidell, Louisiana

Offline Doug Moon

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1861
Re: Vortex Generators - Development and Installation.
« Reply #29 on: September 10, 2011, 10:35:17 PM »
Today we had perfect flying weather in Dallas.  Winds light to none from the west.  It was stunt heaven.  My wife and I packed the kids and the gear and headed to the field. 

I took my red and white Riff Raff with me today, this is the plane I finished 2nd to Billy with at the 2010 nats.  I still havent fixed it from my unfortunate error at the 2011 nats this past summer.  So I figured now would be a great time to test these little items out before repairing and refinishing the model.  Plus it would be very beneficial to test on my most competitive plane at the time. 

I used plywood for the generators.  I also run wing gear so I had to move them out just a tad bit further than PJ has suggested.  Not much, maybe an inch. 

I flew the plane once without the VGs attached.  It was very predictable and did all the normal things it does.  One very annoying thing about this plane is I have to constantly stay on top of it to fly two consecutive maneuvers on top of each other.  Dont get me wrong this is a great flying plane but it takes alot of attention or I will be walking my maneuvers all over the place.  I have gotten very used to it at this point.

Then I flew my profile with my kids for their first time in the circle.  It was awesome.  My 3.5 year old son and my 7 year old daughter did great.  We did crash it but a little epoxy and it will be ready for the next go around.  It was so fun to introduce it to them for the first time.

Next I proceeded to CA on the VG on the top and bottom of the wing.  I went with 8 VGs for the test.  I just eyeballed it and put them in place.  I made sure they were right on as far as alignment top and bottom.  I made sure they were pigeon toe angled at each other.  I placed them just ahead of the high point as well.

At take off I could tell there was a difference in the model.  It was flying just a tad wing high.  Maybe it was my imagination but I thought it was wing high.  It did track very well during level flight.  Very locked in.

I turned it up for the loops and it locked in tight.  I was able to do three loops right on top of each other without any trouble or feeling of it trying to walk around. The bottoms were right on track and right on top of each other.  When it came time to do the outside loops the wind had totally died it was calm.  I had to walk back while flying them and I found it alot easier to hit the bottoms while stepping back.  It just seemed to be tracking better where ever it went.  I was also noticing at this point I was having to use more stick pressure to get through the maneuvers.

Next the squares.  It seemed to really show up in the second square both inside and outside.  The plane just doesnt give up as much when in the second maneuver where it has lost a little of initial speed it had on the first square.  Normally if I hit it too hard on the last corner on the second maneuver it will slide or slip a little on exit.  This was not the case this time.  I was still noticing it was needing more stick pressure then normal to get through the corners.  Not alot but a tiny noticeable amount.  The flaps were definitely feeling the effect and it was talking to me through the handle.

The third corner of the triangle was great.  On exit the plane just shoots out straight.  There is no settling in or trying to finesse it in there.  Especially on the second one where many planes need a little help or need to turn out early so as to hit the correct bottom height.  On exit these little devices really show their power.  It is really quite noticeable.

I proceeded through the round 8 it tracked well.  But this plane has always tracked well there.  In the square 8 I was able to really go at it on the second one and it would stay in there tight and not give up a bit on any exit.  It was really cool.  It felt like it would be easier to keep the same corner all the way through the pattern.

It carved out the best vertical 8 this plane has ever done it was as if it had power steering.  The vertical 8 was actually very surprising.  The line tension was more positive and the ability to place the plane more precisely where you wanted it was very evident. 

The hourglass was another eye opener.  If I hit third corner, top left one, of the hourglass too hard the plane will hop a little as it comes around to make the final leg.  I have noticed this little hop or wiggle in many stunt planes I have watched over the years. With these little jewels on there this was not the case.  And you can go deep into the last corner and it just exits flat with no settling.  I did several to make sure I wasnt making this up in my head and sure enough it was just cleaner in all corners and legs of that maneuver. 

Didnt notice anything in the o8 or clover, except for the added stick pressure.  It did track well. 

I didnt notice anything on the landing decent either but this plane has always really had a really great glide.  I am sure they doing something though.

All in all I would say there is a REAL improvement there.  It is so much CLEANER all the way through the flight.

It was a real pain in butt to clean the wing with those on there.  I am thinking if I decide to put these on my new model, in finishing stage now, I will go ahead and make slots for them in the wing.  Then finish and buff.  Then put then in the slots last as opposed to gluing them onto the surface. 

It was a very cool experiment and I would encourage anyone to try it out and see what they think.

PJ, Thanks for posting all of that really great useful information.  It made this little test of mine prove out on the first go around.  Thanks again.
Doug Moon
AMA 496454
Dougmoon12@yahoo.com

Offline john e. holliday

  • 2018 Supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 19925
Re: Vortex Generators - Development and Installation.
« Reply #30 on: September 11, 2011, 07:16:48 AM »
This is the best testimony I have seen for all the extra work involved.   Would it be worth it to me?  I don't know as anyone that has watched me fly knows I am not that serious.   H^^
John E. "DOC" Holliday
10421 West 56th Terrace
Shawnee, KANSAS  66203
AMA 23530

Have fun as I have and is still breaking a record.

Offline Allan Perret

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1924
  • Proverbs
Re: Vortex Generators - Development and Installation.
« Reply #31 on: September 11, 2011, 08:16:40 AM »
Today we had perfect flying weather in Dallas.  Winds light to none from the west.  It was stunt heaven.  My wife and I packed the kids and the gear and headed to the field. 

I took my red and white Riff Raff with me today, this is the plane I finished 2nd to Billy with at the 2010 nats.  I still havent fixed it from my unfortunate error at the 2011 nats this past summer.  So I figured now would be a great time to test these little items out before repairing and refinishing the model.  Plus it would be very beneficial to test on my most competitive plane at the time. 

I used plywood for the generators.  I also run wing gear so I had to move them out just a tad bit further than PJ has suggested.  Not much, maybe an inch. 

I flew the plane once without the VGs attached.  It was very predictable and did all the normal things it does.  One very annoying thing about this plane is I have to constantly stay on top of it to fly two consecutive maneuvers on top of each other.  Dont get me wrong this is a great flying plane but it takes alot of attention or I will be walking my maneuvers all over the place.  I have gotten very used to it at this point.

Then I flew my profile with my kids for their first time in the circle.  It was awesome.  My 3.5 year old son and my 7 year old daughter did great.  We did crash it but a little epoxy and it will be ready for the next go around.  It was so fun to introduce it to them for the first time.

Next I proceeded to CA on the VG on the top and bottom of the wing.  I went with 8 VGs for the test.  I just eyeballed it and put them in place.  I made sure they were right on as far as alignment top and bottom.  I made sure they were pigeon toe angled at each other.  I placed them just ahead of the high point as well.

At take off I could tell there was a difference in the model.  It was flying just a tad wing high.  Maybe it was my imagination but I thought it was wing high.  It did track very well during level flight.  Very locked in.

I turned it up for the loops and it locked in tight.  I was able to do three loops right on top of each other without any trouble or feeling of it trying to walk around. The bottoms were right on track and right on top of each other.  When it came time to do the outside loops the wind had totally died it was calm.  I had to walk back while flying them and I found it alot easier to hit the bottoms while stepping back.  It just seemed to be tracking better where ever it went.  I was also noticing at this point I was having to use more stick pressure to get through the maneuvers.

Next the squares.  It seemed to really show up in the second square both inside and outside.  The plane just doesnt give up as much when in the second maneuver where it has lost a little of initial speed it had on the first square.  Normally if I hit it too hard on the last corner on the second maneuver it will slide or slip a little on exit.  This was not the case this time.  I was still noticing it was needing more stick pressure then normal to get through the corners.  Not alot but a tiny noticeable amount.  The flaps were definitely feeling the effect and it was talking to me through the handle.

The third corner of the triangle was great.  On exit the plane just shoots out straight.  There is no settling in or trying to finesse it in there.  Especially on the second one where many planes need a little help or need to turn out early so as to hit the correct bottom height.  On exit these little devices really show their power.  It is really quite noticeable.

I proceeded through the round 8 it tracked well.  But this plane has always tracked well there.  In the square 8 I was able to really go at it on the second one and it would stay in there tight and not give up a bit on any exit.  It was really cool.  It felt like it would be easier to keep the same corner all the way through the pattern.

It carved out the best vertical 8 this plane has ever done it was as if it had power steering.  The vertical 8 was actually very surprising.  The line tension was more positive and the ability to place the plane more precisely where you wanted it was very evident. 

The hourglass was another eye opener.  If I hit third corner, top left one, of the hourglass too hard the plane will hop a little as it comes around to make the final leg.  I have noticed this little hop or wiggle in many stunt planes I have watched over the years. With these little jewels on there this was not the case.  And you can go deep into the last corner and it just exits flat with no settling.  I did several to make sure I wasnt making this up in my head and sure enough it was just cleaner in all corners and legs of that maneuver. 

Didnt notice anything in the o8 or clover, except for the added stick pressure.  It did track well. 

I didnt notice anything on the landing decent either but this plane has always really had a really great glide.  I am sure they doing something though.

All in all I would say there is a REAL improvement there.  It is so much CLEANER all the way through the flight.

It was a real pain in butt to clean the wing with those on there.  I am thinking if I decide to put these on my new model, in finishing stage now, I will go ahead and make slots for them in the wing.  Then finish and buff.  Then put then in the slots last as opposed to gluing them onto the surface. 

It was a very cool experiment and I would encourage anyone to try it out and see what they think.

PJ, Thanks for posting all of that really great useful information.  It made this little test of mine prove out on the first go around.  Thanks again.
What is it that accounts for the added stick pressure, the better attached boundry layer ?
I was thinking the same thing about the slots.  You could build them into the wing surface.  Plug in VG's for flight, pull them out for cleaning and buffing.
Allan Perret
AMA 302406
Slidell, Louisiana

Offline PJ Rowland

  • AUS - 29541 AMA - 809970
  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1914
  • Melbourne - AUSTRALIA
Re: Vortex Generators - Development and Installation.
« Reply #32 on: September 11, 2011, 09:16:44 PM »
Thanks the information Doug..

Id like to comment on a couple of things :

Firstly - to you, going out on a limp like this and doing an experiement like this - is to a certain degree a leap of faith on your half. With the ideas of improveing performance I applaude you. To have a flier of your caliber - Top 5 material go out and practice what I've been developing - and see exactly what I see - but also be so impressed with the added performance - is indeed a great endoresment.
Keep in mind this " riff Raff" model would have placed VERY highly at the US nats if not for the incident. So we are not talking about a hack model here; but a seasoned flier- with a model in great trim, and at the top of his game.


As for the added stick pressure - I cannot really comment on that - all my models ( except my classic plane ) feature the Howard Rush style boost tabs - Which I have also been devloping over the last 13 years - mine to differ to Howards, to reduce that load.  At first guess Id say its fairly obvious that the Vortex Generators are doing exactly what they are meant to do - Force the airflow over the wing for a longer period of time - the force to deflect the flaps has increased becasue you have more concentrated airflow from your wing travelling further down - possibly down to the flaps.



Flying wing tip high on take off.. At a guess I would say one of two things has happened :

1: The generators were not PERFECTLY alligned.. Howver I have done some BAD installs of this in the past - patch job on the field or during tests.. and havent found HUGE differences once the model was in trim.

2: The generators were installed correctly and its shown up the trim of the model was not correct to start with. I dont mean that as a slight on the model - more to the point, I find I have to be extremely critical upon wing trim with the models. With the generators you are in effect magnifying the flying charactaristics of the model. If its a little out before - it will have more airflow over the wings and accentuate this problem.
I did find this to be the case.


Next the squares.  It seemed to really show up in the second square both inside and outside.  The plane just doesnt give up as much when in the second maneuver where it has lost a little of initial speed it had on the first square.


Yes indeed - it allows the engine and package to work properly. If you have a bad plane initally with weight or so forth- it makes it usable. If you have a light plane with big horsepower engine ( like yours ) they make the model even better.
As I said from the outset - it improves tracking, and most aspects of what we are trying to do.



It carved out the best vertical 8 this plane has ever done it was as if it had power steering.  The vertical 8 was actually very surprising.  The line tension was more positive and the ability to place the plane more precisely where you wanted it was very evident.  
 

 
Thats interesting you said that - I didnt really think about that during the write up - For me its hard to be subjective about some of these things becsaue I've been doing it for so long, not only developing my own building, flying, and plane design but working on being a better flyer in the longrun.

I did notice 2 years ago - I flew a friends model which was a tradition Pipe SV style model wiht .61 - it flew rather well. When I flew it, I struggled with the vertical 8's I never had confidence in it. Pulling vertical, line tension but the killer was the intersection coming down vertically from the outside loop - I could not for love nor money get it back accurately to the 45' mark.  What I suspect is happening is you are washing off alot of airspeed and really fighting a number of factors, gravity, angle of attack, airspeed.  

With the generators, it just keeps everything fresh, charged and new..  Like the second manouver series of the hortz squares, you can continue to drive with the same confidence as the first.


Landings: I tend to notice this a little more when the wind picks up. Along with general level flight tracking. Not dropping as much downwind, and not raising upwind. I tended to notice alot more ground effect which made dropping it down ( touchdown ) a little harder.

Buffing: I have been toying around with this one for a while.. I use a machine to buff the model - so I prefer to finish the model off complete - and then CA them on after. - Also using carbon fiber is a BIG improvement to how long they stay on.  For the record - once mine are on, If I try to remove them its quite difficult. You wont simply knock them off by wiping around them.. Taking a pair of plies and pulling will eventualyl get them off.

As I said I tend to put a drop of medium ca on the edges also.

If you develop a better way to install them with slots and so forth I'd love to have a go at that.
If I understand it correctly - you want to cut slots into the wing - and have them sit static ? Id be concerned at the amount of airflow and force they are under ;they might not stay in.. even if they are made ULTRA tight.. however I have done no experiements to this effect - keep me informed as to any developments please !

I have tried painting them in the past - but ran into extra problems there.. I find it alot easier to add them later.

I am thinking if I decide to put these on my new model.....

By the sounds of it - you noticed alot of REAL improvements...... my advice, dont put them on the new model.....I'm coming back in 2013 the last thing I need is to loose any advantage I might have developed.  ;D


All in all - sounds like you were impressed with what Vortex generators offered and backed up exactly what I found. To a certain degree it validates my own experiences to hear someone else try it. Even though I have done numerous tests on numerous models - something about hearing others try it is validating..

Now the question for you must be- like stab plates, Do I run with these from now on ?

Thanks for the update.....



Allan : No I havent found any difference to Wing mount vs Fuse.
If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” - Bruce Lee.

...

I Yearn for a world where chickens can cross the road without having their motives questioned.

Offline Doug Moon

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1861
Re: Vortex Generators - Development and Installation.
« Reply #33 on: September 11, 2011, 10:04:26 PM »
PJ, i was thinking of installing with a slot in the wing only so I could completely finish the model and buff then glue them into the slot.  Instead of just glue them on the surface. 

I am still thinking of how to do it. I will use carbon for sure. 

I will keep you updated for sure. 

I have seen the boost tabs that Howard has on his flaps.  It would seem that the little sections that move opposite the flap travel would in fact relieve stick pressure but at the same time it would lose some active lift.  It would seem you could just make the flaps a little smaller and get the same effect...

Can you guys eloborate on them a little bit?  I think I remember some talk way back when Howard first started showing these little nuggets but i a not sure where it is.  If you have a link please post it.

Thanks

Doug Moon
AMA 496454
Dougmoon12@yahoo.com

Offline PJ Rowland

  • AUS - 29541 AMA - 809970
  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1914
  • Melbourne - AUSTRALIA
Re: Vortex Generators - Development and Installation.
« Reply #34 on: September 11, 2011, 11:47:50 PM »
On my next day off - I will add in a new post like I did with the Vortex generators. - There's alot of background information. Needless to say Howard and I differ on a few things when it comes to these units.

Mostly to do with size and location.


Thanks again Doug - Thats mainly why I build templates for the installations of them - I do it after buffing and they dont go anywhere. They are fairly robust once in properly, traveled overseas with the model, interstate with it in the car- in and out of the hanger and done properly, they last.

I don't think there is a "right way" or a "wrong way" to install them, I just haven't found anything better but thats not to say there isnt a better way of doing it.. by the time I get to that point im over building and finishing I want to seal up the flaps, install the VG's and go fly !

I've re-read your post a few times now - still got a smile on my face.
As you know CA and carbon is a potent mix ! Ply.. not so much..
If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” - Bruce Lee.

...

I Yearn for a world where chickens can cross the road without having their motives questioned.

Offline Howard Rush

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6332
Re: Vortex Generators - Development and Installation.
« Reply #35 on: September 12, 2011, 03:36:11 AM »
I have seen the boost tabs that Howard has on his flaps.  It would seem that the little sections that move opposite the flap travel would in fact relieve stick pressure but at the same time it would lose some active lift.  It would seem you could just make the flaps a little smaller and get the same effect...

Can you guys eloborate on them a little bit?  I think I remember some talk way back when Howard first started showing these little nuggets but i a not sure where it is.  If you have a link please post it.

Curiously, they have little effect on lift, at least when used together with a carbon flap torque tube.  I increased flap chord .1" over that of the standard Impact because I thought they would kill some lift, but I had to increase elevator travel because they don't.  They reduce flap hinge moment, which, among other things, reduces stick force. 

Balance tabs are standard aerodynamic doodads.  They date back to the late 1920s. Here's an interesting paper from 1936: http://aerade.cranfield.ac.uk/ara/1936/naca-report-528.pdf .
The Jive Combat Team
Making combat and stunt great again

Offline PJ Rowland

  • AUS - 29541 AMA - 809970
  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1914
  • Melbourne - AUSTRALIA
Re: Vortex Generators - Development and Installation.
« Reply #36 on: September 12, 2011, 05:52:46 AM »
Well after reading all that - Its pretty clear any article I write would be pointless compared to a study of that length!

Tell me Howard - did you study that in HighSchool?  ;D

Interesting that they talk about the location that outboard tab is more effective but structually not preferred.. Interesting they also mention the 3 locations tested, Inboard, centre and outboard there was very little difference between them - however from a structual perspective, Inboard would also be preferred. That would in part explain why you run them there, not central like I do.

Thinking back - I dont recall exactly why I didnt use inboard location. It was so long ago now.. I should in intersts of science, revisit testing that - however it works so well It probably not going to reveal anything new - upon reading that article.

I have to confess - alot of that went over my head - I do however know what I feel inflight. I too often wondered how much lift was sapped from the flaps, thats why in part over time, I have gradually reduced the overall size of them .

Howard uses a Tab that is closer to 6 - 7 Inches in length with a root chord close to 1 "

Mine are quite abit smaller - Length of 3 " with a root chord closer to 1/2 " - So half size basically. - With no adverse effects on performance, and certainly notabicle amounts of reduced stick load pressure.

I think I will just post some photos in a new thread to show those whom might not have seen it - what it is - and I will leave the Maths and Excell spreadsheets to howard.. I will just say they work, he can explain with equations why..

If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” - Bruce Lee.

...

I Yearn for a world where chickens can cross the road without having their motives questioned.

Offline Dennis Toth

  • 2014 Supporters
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2121
Re: Vortex Generators - Development and Installation.
« Reply #37 on: September 12, 2011, 09:18:33 AM »
PJ,
This is very interesting and Doug's experience with them is also important. Seems they are not that sensitive on the install, obviously the more accurate the better but still it shows the average flier could install them and get improvement. This should work really good with electrics as the power to overcome any additional drag load is just automatically applied, trick here (and likely with IC also) is the prop being hooked up to bit and pull.

On the added control pressure - would adjusting the CG a little rearward help? Seems with the added stability coming off the turns we could play with this some.

I was wondering if making a template that keyed off the trailing edge hinge line would allow easier gauging? I'm thinking that since most ships have a straight hinge line it would make alignment simpler. Question is how do you set the angles?

Best,        DennisT

Offline PJ Rowland

  • AUS - 29541 AMA - 809970
  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1914
  • Melbourne - AUSTRALIA
Re: Vortex Generators - Development and Installation.
« Reply #38 on: September 12, 2011, 05:10:54 PM »
Adjusting the cg isnt preferable - you still want the plane to lock in and sit the same way. How you opt to reduce that stick load is up to you. I know how I do it and how Howard does it..

As for alignment - I create my template to go off the leading edge - I set the angles with a protractor.  I take into account the leading edge sweep.


Id be interested to know if Doug found more load on the engine - or a decrease in lap times for a given RPM. With my system its reduced along way to almost non noticable levels with modern powerful engines.


If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” - Bruce Lee.

...

I Yearn for a world where chickens can cross the road without having their motives questioned.

Offline bob branch

  • AMA Member
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 897
Re: Vortex Generators - Development and Installation.
« Reply #39 on: September 12, 2011, 06:23:28 PM »
PJ

Could you share how you decided on the spacing of the vg's in the pair? I have flown general aviation aircraft with them and the pairs are usually placed closer. I'm not criticizing but seeking your thoughts. We are also seeing vg's show up on rc aircraft over the last few years and I have flown some planes with them. btw, in general aviation aircraft they are used primarily to modify the stall characteristics of different airfoils. Many bush planes use them to lower the wing's stall speed. One twin I have flown uses them on vertical and horizontal stabs to give more control surface authority under single engine flight regimes.  We have also used them on racing sailboat keels and rudders over the years. Lots of applications.

bob branch

Offline PJ Rowland

  • AUS - 29541 AMA - 809970
  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1914
  • Melbourne - AUSTRALIA
Re: Vortex Generators - Development and Installation.
« Reply #40 on: September 12, 2011, 09:47:25 PM »
Placement was dictated by my desire to make it easier to clean!  I have used them fairly close together ( spaced 3/4" apart ) however its a real pain to clean the model down - I have had them spaced as far apart as 4" with no changes to control. Having them this distance - 3 " or so allows you to clean in between them without getting to fancy - Over time I just got used to being careful around that 1 spot on the model. - Close is too difficult. Im sure you could go out as far as 10" but they you start issolating them and makes it more prone to damage.

What makes it different - generally in aviation full size the amounts are far more - We are only using 1 par per wing for traditional stunt ship design - If you have a heavier wing loading I recommend using 2 pairs ( like Johns model - or the Bomber for examples ) In general use 1 pair is sufficient. I also felt that spacing them further apart gave a little more authority over a larger portion of the wing.

Again its a balancing act - between not creating so much drag the model turns too slowly ( which was the case with some of the inital tests. ) You need jsut enough to get the desired effect without altering the performance of the model too much.

I think its pretty spot on now - Dougs test proved the reproduction of the technique with the desired improvements - without much in the way of effecting how the models fly normally from a control perspective.
If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” - Bruce Lee.

...

I Yearn for a world where chickens can cross the road without having their motives questioned.

Offline bob branch

  • AMA Member
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 897
Re: Vortex Generators - Development and Installation.
« Reply #41 on: September 13, 2011, 05:17:29 AM »
Thanks PJ. Good explanation and more depth to the evolution of your tests.

bob branch  H^^

Offline Doug Moon

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1861
Re: Vortex Generators - Development and Installation.
« Reply #42 on: September 13, 2011, 06:11:51 PM »
As far as more load on the motor, there was no noticeable change in the engine run.  I was watching for it and felt or heard nothing.

As for the added stick pressure, it wasnt an amount I would trim away from or thought was too much.  But a teeny tiny bit of handle space would take care of it.  But I think I would get very used to it in few flights.

I was thinking today about installation.  Since they are just in front of the high point there would be no interference with the control system if each VG was one long one that stretched from the top to the bottom.  Then about half way up the piece of carbon you put in a dimple.  Inside the wing you install ball on a spring type socket and they can jut snap in and out like Yatsenko gear.  Now, how do you make a socket like that?
Doug Moon
AMA 496454
Dougmoon12@yahoo.com

Offline Doug Moon

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1861
Re: Vortex Generators - Development and Installation.
« Reply #43 on: September 13, 2011, 06:21:41 PM »
......They reduce flap hinge moment....


I know this is probably a dumb question but here goes.

What is meant when you say flap hinge moment?  Or control surface hinge moment?

Doug Moon
AMA 496454
Dougmoon12@yahoo.com

Offline Howard Rush

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6332
Re: Vortex Generators - Development and Installation.
« Reply #44 on: September 13, 2011, 06:34:54 PM »
As far as more load on the motor, there was no noticeable change in the engine run.  I was watching for it and felt or heard nothing.

As for the added stick pressure, it wasnt an amount I would trim away from or thought was too much.  But a teeny tiny bit of handle space would take care of it.  But I think I would get very used to it in few flights.

I was thinking today about installation.  Since they are just in front of the high point there would be no interference with the control system if each VG was one long one that stretched from the top to the bottom.  Then about half way up the piece of carbon you put in a dimple.  Inside the wing you install ball on a spring type socket and they can jut snap in and out like Yatsenko gear.  Now, how do you make a socket like that?

That sounds like a cool idea.  How about sliding the carbon through a box that surrounds it and having a music-wire knee that goes into the dimple?  There's no particular need to use carbon, though.  You could use something else and paint it to match your plane. 

Air might leak through the slot.  That might not be good. 
The Jive Combat Team
Making combat and stunt great again

Offline Howard Rush

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6332
Re: Vortex Generators - Development and Installation.
« Reply #45 on: September 13, 2011, 06:38:04 PM »
What is meant when you say flap hinge moment?  Or control surface hinge moment?

The torque produced by air loads on the flap or other control surface.  I think it's a big deal. 
The Jive Combat Team
Making combat and stunt great again

Offline Randy Powell

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 9956
  • TreeTop Flyer
Re: Vortex Generators - Development and Installation.
« Reply #46 on: September 13, 2011, 06:43:32 PM »
Howard generates his own vortex.
Member in good standing of P.I.S.T
(Politically Incorrect Stunt Team)
AMA 67711

Randy Powell

Offline Jeff Traxler

  • T-Bone
  • 2013 Supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 651
Re: Vortex Generators - Development and Installation.
« Reply #47 on: September 13, 2011, 07:41:13 PM »
[quote author=Doug Moon link=topic=23110.msg222465#msg222465 date=1315959111.

I was thinking today about installation.  Since they are just in front of the high point there would be no interference with the control system if each VG was one long one that stretched from the top to the bottom.  Then about half way up the piece of carbon you put in a dimple.  Inside the wing you install ball on a spring type socket and they can jut snap in and out like Yatsenko gear.  Now, how do you make a socket like that?
[/quote]

      Hi Doug,A luthiers spiral downcut inlay router bit would be just the trick.The cutting edge is spiraled around the shank and it cuts downward towards the serface.That way it is shearing the grain downward and it leaves a very nice clean slot with no tearout from the spinning tool.They are sharp enough to cleanly rout balsa and will go through carbon mat with no problem.When properly adjusted for depth of cut a very clean flat bottom slot will be created.The smallest one if they still make them was .025 and you can get them from some vendors up to an 1/8th.They come with an 1/8th" shank so a Dremel with a router base is the PERFECT match for the bits.
      To cut the slots all you have to do is set the bit for the proper depth.Mark where the location will be.Measure the distance between the edge of the cutter and the outside edge of the base.Now place a flexable straight edge parallel with the location of the VGs at the same measurement you got from the cutter/base.Make sure there is a lot of light so you can see the position of the VGs.Put the base against the straight edge and plunge the bit in and push it the length of the VG.Carefully raise the bit out of the work with the base still tight agianst the straight edge and you will end up with a perfectly straight slot the proper length and depth.It is very important that you secure the straight edge so it does not move from the pressure of holding the router base agianst it.Failure to do so causes cursewords we can't type on Stunthanger!!!!!A slot of .040 depth with a .020 thickness VG effectively quintuples the glue surfece area over a VG with the only glue surface being the bottom butt glued to the wing.I think if they are installed in this manner they will be very hard to accidentally break them off.If you do it will probably take a little hunk of wing too.
     Now for the good news.The bits aint cheep but they can easily be obtained.When I did a lot of Mother of Pearl inlay work on the guitars I was making I used to get them from Stewart-McDonald's Guitar Shop Supply and Luthiers Merchantile Exchange.Go to their websites and click on "Inlay Supplies" or search spiral downcut bit and they should be easily found.Don't know how to post a link or I would.Hope this helps your installation decision,Jeff
If you wanna sing the blues(Fly Stunt) you gotta pay your dues and "I know it don't come easy"

Offline PJ Rowland

  • AUS - 29541 AMA - 809970
  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1914
  • Melbourne - AUSTRALIA
Re: Vortex Generators - Development and Installation.
« Reply #48 on: September 14, 2011, 02:30:26 AM »
I think i'l stick to Carbon and CA.. -  Sounds like its getting to complex for my little simple Australian mind to comprehend.

I would love to see someone else do development work on this system - perhaps in 10 years there will be more diverse ranges of Vortex Control. For now I have maxed out my abilities. I have enjoyed reading this thread - I don't think I have anything more to add - that will benifit anyone.

Doug interesting you didnt notice anything with the engine load - I always found the engines ran nicer with more load - that level of load was difficult to acheive without them. For example with my Stalker combination - I generally have alot more pitch - with the engine loaded up more power is delivered quit well.

When I say alot more pitch - my Gieseke Nobler at the Us Nats ran 11.5 x 8.25 2B undercamber - with 15% Nitro Sig Champion.
If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” - Bruce Lee.

...

I Yearn for a world where chickens can cross the road without having their motives questioned.

Offline Allan Perret

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1924
  • Proverbs
Re: Vortex Generators - Development and Installation.
« Reply #49 on: September 14, 2011, 09:06:26 AM »
I was thinking today about installation.  Since they are just in front of the high point there would be no interference with the control system if each VG was one long one that stretched from the top to the bottom.  Then about half way up the piece of carbon you put in a dimple.  Inside the wing you install ball on a spring type socket and they can jut snap in and out like Yatsenko gear.  Now, how do you make a socket like that?
I like this idea of a socket thru the wing for a pair of VG's top and bottom.  The socket and matching VG carrier/mount could be larger in cross section than the VG itself, making it easier to construct and install in wing.   I'm thinking the carrier would be spruce or bass stick, 1/16 x 1/4.  Wing socket could be built around the stick/carrier for a good fit, and then installed permanently in wing.  I have some idea how to make detent to keep VG carrier centered in socket,  but not easy to describe without actually doing it and taking pictures.  Will attempt that on next build and post it if happy with results.     
Allan Perret
AMA 302406
Slidell, Louisiana

Offline bob branch

  • AMA Member
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 897
Re: Vortex Generators - Development and Installation.
« Reply #50 on: September 14, 2011, 05:54:49 PM »
I was installing a set of the VG's on my C-14 carbon tube fuse electric tonight and found I was out of carbon fiber sheet. Didn't feel like laying any up so I sought another material. Turns out credit card stock is about the same thickness and easily shaped with blade and sandpaper. Not brittle like plywood is either. I'll flight test on Friday and post results.

bob branch

Offline bob branch

  • AMA Member
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 897
Re: Vortex Generators - Development and Installation.
« Reply #51 on: September 16, 2011, 06:25:02 PM »
This is a flight report of my C14 carbon fuse electric profile with the vortex generators applied. I applied 2 pairs on each wing panel top and bottom. Size, shape, and spacing as PJ recommended. Details of the plane are in the build thread on it in the electric section. It utilizes Brodak P-40 wing and tail and the fuse length and moments are from the Brodak T-Rex. Flight characteristics are identical to the T-Rex except for less pull on lines due to lower weight. I fly both on 63 ft lines. Power is by axi 2826/12, phoenix 45, 3700 mah 4S pack, and APC 12X6EP prop, and hubin fm9 timer. . My normal lap speed is 5.25 seconds. The plane flies very well. Corners are very sharp and flat on exit. Rounds are smooth and require no steering to overlay on themselves. Line tension is solid thru the entire pattern except 3rd corner of the hour glass. This is the only electric with pusher prop configuration that I have not had heavy line tension at this corner. Probably because I have less motor offset than any of my other electrics. The only major thing I do not like and what I was hoping to improve is in level flight. The plane does not hunt. It locks in quite well. Not as well as my SV-11 electric but very well. Observers see no hunting but I notice I have to fly level whereas the SV I do not. I do not have to even think about level. It just stays there. BTW, my T-Rex acts identically in level flight to the C-14.

One thing about the electric is that we have accurate repeatable digitally set rpm. So I was able to quantify the drag difference quite accurately. My flying partner today was Frank Carlisle and he also flew the plane and I'll give you his input also.  First the drag issue. Temp was about 60 degrees and winds were variable 5mph or less today. Lap times initially came out to 5.45 seconds. So .2 seconds per lap slower. I increased the rpm by 60 rpm. This brought the lap time to 5.25 sec. So there is the amount of drag from the 4 VG's on each side of the wing. The level flight improved significantly. It is very locked in now. Frank in observing saw nothing he would call hunting and in his flight he felt that level was very locked in. 

The round maneuvers were easy and repeatable as they always are on this plane. I could not find any significant difference here except that in the vertical 8 I flew the best ones I have ever flown on every flight. It seemed that the top loop was much more consistent with the VG's. The overhead loops gave me the same impression. They tracked better than usual on this plane and the repeatability was right on. In the 6 flights with the wind moving around as it was there is no way I could have gotten the wind that perfect every flight. There was a difference in tracking up high.

Corners were very crisp and exits flat as always. But I felt I could repeatedly locate the corners more accurately. I got the feeling the plane responded more quickly when the control input was made. Depending on the wind I had a big tree or the sun for the vertical intersections on the square 8 and it was easier than usual to hit them. The third corner of the hour glass became more electric normal with more line tension there. I should note the governor prevents wind up or acceleration for those not familiar with it so the feeling is of the plane flying at the same speed at all places in maneuvers. This was not happening because of any airspeed change but from the VG's. Had I not installed the VG's I was going to adjust engine offset a tad more. Right now I fly with one washer of offset.

Glide did not seem appreciably different on this plane. It is a very easy plane to get a really good takeoff with and lands very nicely as well. I should note the gear are considerably longer than P-40 stock gear. In fact they are the stock gear from the T-Rex.

Later in the day I increased the line rake a quarter of an inch which slowed the airplane to 5.3 sec laps. Line tension was increased of course. But the plane still  cornered as crisply at the slower speed and there was no line tension loss at the slower speed. Later I slowed the plane to 5.5 sec lap and still no loss of line tension. The plane could be easily flown at that speed.

So I felt there was a noticeable difference in a couple of places on this plane. I will be installing them on the T Rex as well and since my SV is an arf a I feel a little heavier than it should be I will add a set there as well. It tends to develop a tad of a tip stall if I hit a corner too hard. I'd like to see if it goes away with them. That would be a very positive result from them. When I flight test them I'll post the results.

Thanks again PJ for your work on these and for sharing it. I think I finally came to understand whey the spacing being larger than in full scale planes works on a stunter. Its our circular flight path. The vorticies will not be trailing straight aft but will be sweeping outboard. This results in a longer path before intersecting the trailing edge and thus a wider vortex. If you look at it that way an look at the wing with them on you can see, it allows a much larger coverage area than if the plane was traveling a straight line path. At any rate I think this is something people would find interesting to experiment with. They certainly have the potential to solve some sticky problems with some planes. Oh, btw, I did not notice any stick force difference in my tests. Frank could not input because he has not flown the plane before. He did, however very much like the way the plane flew. He especially liked the corner.

bob branch  H^^

Offline bob branch

  • AMA Member
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 897
Re: Vortex Generators - Development and Installation.
« Reply #52 on: September 16, 2011, 06:26:03 PM »
Oh, one more thing. With electron power no issue with cleaning the plane with them on. .... sorry.....  LL~

bob branch

Offline PJ Rowland

  • AUS - 29541 AMA - 809970
  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1914
  • Melbourne - AUSTRALIA
Re: Vortex Generators - Development and Installation.
« Reply #53 on: September 16, 2011, 07:02:23 PM »
Thanks for posting that Bob.

I would say the difference you are experience with stick force is partly due to the size of the model ( 40 size if I recall )

Compared to a full sized stunter per-say. I dont run Boost tabs on my classic model - but I certainly do on my 60 sized ships. I only notice minor stick force increase with the smaller models.


As stated earlier - one of the main reasons to run these is for precision - repeatable precsion. - you can track manouvers easier, lock in level flight, which in turn locks in round tracking. I love doing reverse wingovers, you hit the corner, and it locks in vertical tracking. Drive deeper into the corner.

Glide - I find it in windy conditions better more so than regular sessions.

It will only improve what you have, it's not going to harm any aspect of the ship. - Part of the reason to only run 1 pair is to reduce the drag but retain the charactisics of Vortex Generators.
If the model is great - it will remain great just do things better .
If the model isnt amazing - they will help but wont work miracles.

Great to hear the vertical 8's are great - Again makes everything.. better.




Id say the thinner you make them ( like with carbon ) the better the system seems to be. 
If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” - Bruce Lee.

...

I Yearn for a world where chickens can cross the road without having their motives questioned.


Tags: