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Author Topic: Vortex Generators  (Read 14818 times)

Offline RC Storick

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Re: Vortex Generators
« Reply #50 on: September 19, 2014, 10:54:14 PM »
  Differential flaps didn't work well, so nobody uses them.

The last very significant  innovation in stunt was electric feedback control (2010?). Prior to that, and going back in time,

electric/lithium polymer batteries (early 2000s),
tuned pipe and/or low pitch props (86)
the low-aspect ratio tail (early 80's),
increased tail moment (sorry howard) and associated aft CG (78/9),
increased tail volume (71-72). That takes us back to the early 70's.

     BTW, since you are an expert on the history of stunt, what innovation did the Nobler introduce? Because it's almost certainly not what you think, and it's almost certainly something you would be arguing against vehemently if some did it now. To save you some time, it wasn't coupled flaps and it wasn't the 4-2 break/slow flying. 

    Brett

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Offline Avaiojet

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Re: Vortex Generators
« Reply #51 on: September 20, 2014, 07:16:22 AM »
Quote
what innovation did the Nobler introduce?

That's an easy one.

You could have an ugly plane that can fly well.
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Offline Derek Barry

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Re: Vortex Generators
« Reply #52 on: September 20, 2014, 07:52:11 AM »
Like "others", you miss the point entirely. They are not there to make a porker fly. They are there to make things more consistent.

Isn't one of the side effects making a porker fly better? I have heard enough people describe what the VGs do so I do not doubt that they are doing something. I think you miss the point, to me, they are ugly. I am not convinced that they do "enough" for me to be willing to screw up the finish on my plane. Maybe if I could figure out a good way to make them part of the finish I would feel differently.

Also, I have found that my inconsistencies have less to do with the design of my planes or the way it flies and more to do with the fact that I fly about 30 flights a year and 20 of those are on the L-pad.

Derek

Offline Doug Moon

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Re: Vortex Generators
« Reply #53 on: September 20, 2014, 08:27:38 AM »
Derek,

You find them on light weight planes as well.

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Offline Derek Barry

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Re: Vortex Generators
« Reply #54 on: September 20, 2014, 09:04:45 AM »
Derek,

You find them on light weight planes as well.



Well damn.

Derek

Offline Gene O'Keefe

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Re: Vortex Generators
« Reply #55 on: September 20, 2014, 09:08:39 AM »
Not sure how much flak I'll get for this .... but didn't people think that if you sailed off into the ocean you would fall off as the world was flat ?   and  didn't people think that the planet earth was in the center and everything else revolved around it ?  and didn't doctors think it was a foolish idea to wash their hands before touching another patient ? -- so it very much exists a possibility that until proven false VG's really do work from even a small amount to large amount ?
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Offline Howard Rush

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Re: Vortex Generators
« Reply #56 on: September 20, 2014, 11:27:54 AM »
I think you miss the point, to me, they are ugly. I am not convinced that they do "enough" for me to be willing to screw up the finish on my plane.

In development at Jive Combat Team Laboratories as we speak are VGs with integral LEDs.  The printed circuit array on the wing surface should fit in nicely with the Matrix paint scheme.
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Online Dave_Trible

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Re: Vortex Generators
« Reply #57 on: September 20, 2014, 01:09:16 PM »
I'm going to give it a try.  In Ozark fashion I've found a cheap substitute for those high tech jobs. (Sorry Howard).  I'm taking this clear acetal corner protector -4 feet for two bucks- and trimming down to spec.  It's about .040x5/8"x5/8".  This has adhesive strips on as purchased but will be removed.  It's clear so wouldn't make the birds at the flying field think they are bugs and attack.  

Dave



Counterfeits *. The invisible vortex generator!
« Last Edit: September 21, 2014, 05:32:06 PM by Dave_Trible »
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Offline RandySmith

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Re: Vortex Generators
« Reply #58 on: September 20, 2014, 01:10:30 PM »
In development at Jive Combat Team Laboratories as we speak are VGs with integral LEDs.  The printed circuit array on the wing surface should fit in nicely with the Matrix paint scheme.

The Matrix needs RT"s (VGs)  that have the Magnetic Pulse Generators tied into the circuits array , and able to get direct power from Li-Po source

Randy

Offline RandySmith

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Re: Vortex Generators
« Reply #59 on: September 20, 2014, 01:17:45 PM »
Derek,

You find them on light weight planes as well.



Doug  all this is apples and oranges so far as comparing, they are not there to do the same thing, and NONE of the full scale planes you show, or any others, are doing what the models are doing. I have , in my experience seen VGs  and trips work well with heavy planes, not so well , or not at all on light planes, This comes from testing them, and talking with other who have, plus first hand accounts seeing the difference when applied to OPPs ( Other peps planes).  For example I saw a plane, in terrible damp conditions, in Summer stalling/falling out of maneuvers, adding trips to the wing and stab worked wonders, The same exact time, other light stuntships were NOT affected by the poor conditions.
I think this comes down to individuals planes and circumstances.

Randy

Offline Howard Rush

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Re: Vortex Generators
« Reply #60 on: September 20, 2014, 01:57:11 PM »
The Matrix needs RT"s (VGs)  that have the Magnetic Pulse Generators tied into the circuits array , and able to get direct power from Li-Po source

They will come with "available" (as they say in the car ads) Magnetic Pulse Generators.  The LiPo can be attached directly to Derek's fuel tank and can be charged in the airplane with a cheap no-balance charger for our additional enjoyment.
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Offline Howard Rush

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Re: Vortex Generators
« Reply #61 on: September 20, 2014, 02:11:26 PM »
I'm going to give it a try.  In Ozark fashion I've found a cheap substitute for those high tech jobs. (Sorry Howard).  I'm taking this clear acetal corner protector -4 feet for two bucks- and trimming down to spec.  It's about .040x5/8"x5/8".  This has adhesive strips on as purchased but will be removed.  It's clear so wouldn't make the birds at the flying field think they are bugs and attack. 

Beware of imitations! 3D-printed Rush VGs have cambered airfoils, so they are annoyingly right- or left-handed, and have little nubbins on the side for the laser-cut alignment templates to sit on.  They are also gluten-free and are made without synthetic growth hormones.
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Offline Derek Barry

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Re: Vortex Generators
« Reply #62 on: September 20, 2014, 02:18:07 PM »
In development at Jive Combat Team Laboratories as we speak are VGs with integral LEDs.  The printed circuit array on the wing surface should fit in nicely with the Matrix paint scheme.

Now that is something I would buy.


I was so close to putting LED lights in the pipe tunnel of the Matrix, I had them with me at that Nats. I thought being the only plane in the 180 building with a green glow from beneath was just a little too much. Maybe I will put them in the Cutlass for next year. The battery weighs about .75 oz and the lights don't weigh much at all. I did a test and it did look really cool.
 
Derek

Offline Howard Rush

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Re: Vortex Generators
« Reply #63 on: September 20, 2014, 02:19:44 PM »
If they work on the wing, would they work on the stab?

PW and David use them on stabs.  I've had them on and off the stab of last year's airplane a couple of times.  I couldn't tell any effect.  
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Offline Doug Moon

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Re: Vortex Generators
« Reply #64 on: September 20, 2014, 03:35:21 PM »
Doug  all this is apples and oranges so far as comparing, they are not there to do the same thing, and NONE of the full scale planes you show, or any others, are doing what the models are doing. I have , in my experience seen VGs  and trips work well with heavy planes, not so well , or not at all on light planes, This comes from testing them, and talking with other who have, plus first hand accounts seeing the difference when applied to OPPs ( Other peps planes).  For example I saw a plane, in terrible damp conditions, in Summer stalling/falling out of maneuvers, adding trips to the wing and stab worked wonders, The same exact time, other light stuntships were NOT affected by the poor conditions.
I think this comes down to individuals planes and circumstances.

Randy

If you can create an active boundary across a surface which the air is flowing you will have more control than the surface with a less active boundary layer.  But hey, if you don't think so, then so be it.

If the VG is on there and the surface is moving it is creating a vortex.  That is what they do.  Helping your situation or not, well that would have to do with application and the desired effect.

I for one absolutely hate taped hinge lines.  I have only one plane where I could tell a difference in how the plane performed between taped and non taped hinge lines.  (I have not tested my latest plane due to time constraints.) But I am not going to sit here and say taped hinge lines don't work.  The most certainly do work.  They keep air from traveling through the hinge gap.  That's what they do. Do they make the plane fly better?  Sure for some but not for me and some others I know who have tried it.  So I don't use it.  But the taped lines still do their job.  If you sealed the hinge lines on a 777 (I have no idea how you would do that, one hell of a roll of tape!!) it would do the same thing. Keep air from traveling through the gap.  VGs create a vortex. Doesn't really matter what they are on.  That's what they do.
« Last Edit: September 20, 2014, 10:01:49 PM by Doug Moon »
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Offline Howard Rush

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Re: Vortex Generators
« Reply #65 on: September 20, 2014, 04:11:55 PM »
If you sealed the hinge lines on a 777 (I have no idea how you would do that, one hell of a roll of tape!!) it would do the same thing. Keep air from traveling through the gap.

Not what you'd want to do in that case.
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Offline Doug Moon

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Re: Vortex Generators
« Reply #66 on: September 20, 2014, 04:20:18 PM »
Not what you'd want to do in that case.

Right!  ;D
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Offline Russell Bond

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Re: Vortex Generators
« Reply #67 on: September 20, 2014, 04:37:15 PM »
Alright, I'll put a cat among the pigeons... S?P

What about turbulator tape on the wings the same as Igor's?

Which is better, VGs or the tape?
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Offline RandySmith

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Re: Vortex Generators
« Reply #68 on: September 20, 2014, 04:38:46 PM »
I have tested them too and had positive results.  My testing and evaluation of others applications as well doesn't count? 

As far as comparing planes it is not apples and oranges.  If you can create an active boundary across a surface which the air is flowing you will have more control than the surface with a less active boundary layer.  But hey, if you don't think so, then so be it.

If the VG is on there and the surface is moving it is creating a vortex.  That is what they do.  Helping your situation or not, well that would have to do with application and the desired effect.

I for one absolutely hate taped hinge lines.  I have only one plane where I could tell a difference in how the plane performed between taped and non taped hinge lines.  (I have not tested my latest plane due to time constraints.) But I am not going to sit here and say taped hinge lines don't work.  The most certainly do work.  They keep air from traveling through the hinge gap.  That's what they do. Do they make the plane fly better?  Sure for some but not for me and some others I know who have tried it.  So I don't use it.  But the taped lines still do their job.  If you sealed the hinge lines on a 777 (I have no idea how you would do that, one hell of a roll of tape!!) it would do the same thing. Keep air from traveling through the gap.  VGs create a vortex. Doesn't really matter what they are on.  That's what they do.

To start with NO where did I say your testing didn't matter
NO where did I say they do NOT work  so stop putting words here I never said.
And YES they are doing different things, just because they make a Vortex means little if it is NOt helping you,   means a LOT if it is, go read what i said, from what i have seen they help heavy planes much much more than light ones, they may help your plane and NOt others.
What it boils down to is they may help some planes, that does NOT mean they help ALL planes, They may NOT help some planes, and that does NOT mean they don't help others.
And you are in the minority on seal hinge lines, they **Almost** always help stuntships. Go to show , some things are NOt 100% across the board in what works in stunt.

Randy

Offline RandySmith

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Re: Vortex Generators
« Reply #69 on: September 20, 2014, 04:39:30 PM »
Alright, I'll put a cat among the pigeons... S?P

What about turbulator tape on the wings the same as Igor's?

Which is better, VGs or the tape?

No one knows... for sure

Randy

Offline Randy Cuberly

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Re: Vortex Generators
« Reply #70 on: September 20, 2014, 05:03:26 PM »
Beware of imitations! 3D-printed Rush VGs have cambered airfoils, so they are annoyingly right- or left-handed, and have little nubbins on the side for the laser-cut alignment templates to sit on.  They are also gluten-free and are made without synthetic growth hormones.

UUUhhhhhh Howard, Why do they work better if they're on BACKWARDS!
Understand I'm not complaining...They work for me!

I do agree with some that say they tend to work better on heavy airplanes than light ones (checked on OPP's).  I don't have any light airplanes anymore. 
I think they simply aren't as likely to be needed in a semi-stalled condition on light airplanes..but I'm just a dumb old mechanic...and never got around to Aerodynamics and all those funny smokey graphs you guys use so much.
 LL~ LL~ LL~

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Offline Howard Rush

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Re: Vortex Generators
« Reply #71 on: September 20, 2014, 05:16:59 PM »
Alright, I'll put a cat among the pigeons... S?P

What about turbulator tape on the wings the same as Igor's?

Which is better, VGs or the tape?

Which is better, aluminum or peaches?  They do different things.  VGs make vortices to bring high-speed air down next to the surface.  I don't know what Igor has in mind with his tape, but "turbulators" or trip strips trip the boundary layer from laminar flow to turbulent flow.  Here's a piece on that: http://stunthanger.com/smf/index.php/topic,30917.0.html .  Note Peter Germann's observation about zigzag tape at 10% chord.  

Now that you mention it, the tape would be much easier to embed wiring in for the bling that you so appreciate.  
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Offline Doug Moon

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Re: Vortex Generators
« Reply #72 on: September 20, 2014, 09:21:31 PM »


I am simply saying the VG creates a vortex.  Will it help all planes ALL planes perform better?  That's for each one to decide on their own.

I know I am in the minority on taped lines.  I hear it touted all the time.  I am certain without a doubt they work, stop the air bleed, in ALL cases.  Does it improve the planes performance. That's for the each one to decide on their own.  Only once for me.  Why that is I don't know.  Maybe I just can't tell.  But as I said before I will always try it so I am certain I have explored the possible options to give me any kind of an edge on the circle.

« Last Edit: September 20, 2014, 10:25:36 PM by Doug Moon »
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Offline RandySmith

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Re: Vortex Generators
« Reply #73 on: September 20, 2014, 09:42:26 PM »
I read your first post several times before I responded.  It read to me like you were saying I was out in looney land and had no clue what I was talking about.  I am simply saying the VG creates a vortex.  Will it help all planes ALL planes perform better?  That's for each one to decide on their own.

I know I am in the minority on taped lines.  I hear it touted all the time.  I am certain without a doubt they work, stop the air bleed, in ALL cases.  Does it improve the planes performance. That's for the each one to decide on their own.  Only once for me.  Why that is I don't know.  Maybe I just can't tell.  But as I said before I will always try it so I am certain I have explored the possible options to give me any kind of an edge on the circle.



I am a believer inn looking under all the rocks, you never know what you will find, and I agree, and stated as much, each person has to find out if it works for their program, taping/sealing hingelines is pretty much, one of the most universal things that helps most, hardly any ones gaps are smaller than air molecules , so sealing hingelines  does what Paul says  RTs (radical turbulators) do for his ships... makes them more consistent...  But fact is they do NOT  work the same on all stuntships.
I saw a very good stuntship improved greatly by installing trips on the wing and stab, this is a plane that had no problems at all in most conditions, I have also seen tape stop a stuntship from stalling and falling out of maneuvers like a rock ! 
I also hate putting tape on my flaps.. but do it anyway, and I have very tight gaps.  As you say.. do what you need and explore it all.

Randy

Offline Douglas Ames

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Re: Vortex Generators
« Reply #74 on: September 20, 2014, 10:33:41 PM »
If they work on the wing, would they work on the stab?

Most Stab./ Elev's. on the Stunters I've seen are flat surfaces. (non-airfoil)

They generate a pressure differential at the hinge line rather than "lift" like an airfoil.
_______________________________________________

If they work on the wing, would they work on the stab?

PW and David use them on stabs.  I've had them on and off the stab of last year's airplane a couple of times.  I couldn't tell any effect. 

See above.

ps- My counter tops are Formica from 1981. My sink? Well, that's Harvest Gold.  <=
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Offline RandySmith

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Re: Vortex Generators
« Reply #75 on: September 20, 2014, 11:14:26 PM »
   "quote from: Howard Rush on September 19, 2014, 02:33:36 PM
Worse yet, those people have Corian countertops.

Good lord man! Why would you have such a thing?

Derek  "


LOL  even worse than that, some times it seems like  some stunters wings were made from Corian !!   ;D ;D ;D

Randy

Offline Louis Rankin

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Re: Vortex Generators
« Reply #76 on: September 21, 2014, 09:36:59 AM »
Have any of the carrier guys experimented with VGs yet?  I would be interested to know if it would significantly effect their slow speed flight.
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Offline Joe Yau

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Re: Vortex Generators
« Reply #77 on: September 21, 2014, 11:02:04 AM »
Have any of the carrier guys experimented with VGs yet?  I would be interested to know if it would significantly effect their slow speed flight.

I don't think the local guys has..  But I'm sure it'll be beneficial to some degree after seeing how it improved one of my plane's landing glide.

Offline Randy Cuberly

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Re: Vortex Generators
« Reply #78 on: September 21, 2014, 11:30:07 AM »
Have any of the carrier guys experimented with VGs yet?  I would be interested to know if it would significantly effect their slow speed flight.

Slow speed flight for competitive CL Carrier planes is done at such a high angle of attack (typically 60 degrees) that it's highly unlikely there is any real airflow over the top of the wing.  The airplane simply flies in a totally stalled attitude and the prop keeps it airborne by modulating the throttle.  Hence, VG's would do nothing but add a small amount of weight to the airplane.  <= <=

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Offline Douglas Ames

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Re: Vortex Generators
« Reply #79 on: September 21, 2014, 01:50:54 PM »
Slow speed flight for competitive CL Carrier planes is done at such a high angle of attack (typically 60 degrees) that it's highly unlikely there is any real airflow over the top of the wing.  The airplane simply flies in a totally stalled attitude and the prop keeps it airborne by modulating the throttle.  Hence, VG's would do nothing but add a small amount of weight to the airplane.  <= <=

Randy Cuberly

Hence the Hover vs. Slow flight debate.
Carrier across the pond is still 45 vs. our 60 degree AoA.
They might work better on their models.
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Offline PJ Rowland

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Re: Vortex Generators
« Reply #80 on: September 22, 2014, 07:53:51 PM »
To answer the question my fellow OZ ark asked..

I found anything forward of the highpoint was less effective compared to on or up to 1 " back from the high point.  I run mine 1cm back from the thickest part of the wing @ my CG,  My theory is they work best at the CG.

The direction they sit in relation to the airflow or the forward LE sweep I found didn't make any noticable difference.
 
-----
Now onto the "debate"
-----

Its fair to say that Vortex Generators work. I've done more testing of these things than I care to remember, and more elite racing event are starting to employ some form of drag control. Remember those racing suits the swimmers were wearing to break multiple world records that are now banned ? They were dimpled like a shark skin. Formula 1, Red Bull Air Racing, golf - it doesnt matter - they are looking into ways to CONTROL AIRFLOW.

To say you're not looking into some form of boundary layer control simply means your not looking at every angle and seeking every advantage out there to make your planes fly at a 100% optimum level. ( Which is fine, its no different to practice if your having 50 flights a year or 500 - it reflects your commitment to getting better )

It seems to me, there are some that use them, some that don't - I've had a few conversations with Igor Burger about this exact technology ( why he does or does not use them)  and he doesnt use them exactly, however DOES use Zig Zag tape located along close to the highpoint. Now I also know that the height of a Vortex Generator in our scale would work out to be close to 1/64th - So Im sure the ZigZag tape is working along similar principles to the VG's . I don't believe they are ( the Zig Zag tape ) simply disturbing the airflow, I think they are creating the same effect but in a more subtle way. How do I know this ? I've done back to back testing on both systems. My point isnt to say I think the VG's are better .. or Worse. My testing indicated to ME that the deployment of VG's had a more pronounced noticable effect on more segments of the pattern than the Zig Zag Tape.  Now Igor is a true master and revolutionary thinker and dual World Champion - So his practice is also acceptable, just for me personally I found something that worked differently.

The point of my VG program was to develop them to be as subtle as possible - on my planes they are almost hidden. I also tried hard to develop them to a minimal setup that still gave 95% improvement compared to having them ALL OVER the plane.

I found NO IMPROVEMENT in running them on the stab - When I talk to those who ARE running them on the stab the consensus is "minimal improvement" almost to the point of subjective improvements. Which for me isnt enough, I need concrete ( lost 1/2 oz of tip weight ) obvious.  

 I never shouted out that I thought they were required to make Top 5.. and the fact that Paul Walker or Dave Fitzgerald or Doug Moon or any other "name" flier are using them... isnt relevant. What IS relevant is these are clinical minds and methodical approaches to flying Stunt and they win for a REASON. VG's are not the reason but they are a byproduct of that reason - commitment to improvement.

Its pretty simple really : There is NO ONE RIGHT WAY. Electrics / Pipes / Igor Timers or  PA 75's - Whatever I need to build which will help ME put the model in the right places more times than the other guy is what I want.


Derek : I was on your circle at the Nats and felt I put up some DAMN good flights and you eclipsed me by 20 something points, which was an impressive display. You build light and straight and in general are a Top flier and worthy of a Nats crown. Your views are respected by many, I certainly respect ( and agree with) some of your views and stances on many of the topics you advocate.  However It would be nice if you TESTED them on your own plane with your OWN flying style and then made a judgement call on their effectiveness for your program.

Sparky : "  When Brett Buck has concrete evidence they work and they are on his airplane I might think about it "

That's an indication of many MANY things ... however I will just leave you with a small snipette of basic personality psychology 101.


Conformity = A change in behavior or belief as a result of real or imagined group pressure.

2. Types of conformity

A. Compliance. Publicly acting in accord with social pressure while privately disagreeing. This term best describes the behavior of a person who is motivated to gain reward or avoid punishment. On the level of compliance, many experimenters see little difference between animals and humans, because all organisms respond to rewards and punishments.

B. Identification. As with compliance, we do not behave in a particular way because such behavior is intrinsically satisfying. Rather, we adopt a particular behavior because it puts us in a satisfying relationship to the person or persons with whom we are identifying. We do come to believe in the opinions and values we adopt, though not very strongly. We want to be like some particular person.

EX: Want to be just like your father.

C. Internalization (or acceptance). Both acting and believing in accord with social pressure. This is the most permanent, deeply rooted response to social influence. Internalization is motivated by a desire to be right. If the person who provides the influence is perceived to be trustworthy and of good judgment, we accept the belief he or she advocates and we integrate it into our belief system.



There are COUNTLESS articles on the psychological aspects of conformity... and how that differs from being a free thinker and innovator.




 





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.

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Offline RC Storick

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Re: Vortex Generators
« Reply #81 on: September 22, 2014, 08:22:03 PM »
To PJ If they make you feel good do it. I will spell it out for you it was a joke. I would not glue rat droppings on my plane EVER. If and it's a big IF I was to use them I would build and finish them on the wing.
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Offline Derek Barry

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Re: Vortex Generators
« Reply #82 on: September 23, 2014, 06:44:03 AM »



Derek : I was on your circle at the Nats and felt I put up some DAMN good flights and you eclipsed me by 20 something points, which was an impressive display. You build light and straight and in general are a Top flier and worthy of a Nats crown. Your views are respected by many, I certainly respect ( and agree with) some of your views and stances on many of the topics you advocate.  However It would be nice if you TESTED them on your own plane with your OWN flying style and then made a judgement call on their effectiveness for your program.



But PJ,

That would mean that I would actually have to go out and practice.  LL~

All kidding aside, I still have the VGs that you were kind enough to send me. I do want to test them and if they work well enough for me to keep them on my plane I will be happy to eat crow. (it would not be the first time and certainly won't be the last). With the limited time I have had over the past few years it is difficult for me to find time to do anything stunt related (other than a few contest a year that I never miss).  I do look forward to trying them out and then I will give my honest opinion.

I got Masters tickets this year for the first day of practice. I have two extra if you and Rhiannon would like to come. It would be a long trip for one day in Augusta. Maybe I can just send you a hat?

Derek

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Re: Vortex Generators
« Reply #83 on: September 23, 2014, 08:59:28 AM »
VG tests this morning.
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Offline Derek Barry

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Re: Vortex Generators
« Reply #84 on: September 23, 2014, 09:02:21 AM »
VG tests this morning.

It is confirmed that they will not prevent a crash I guess. Either that, or they are way more harmful to a finish than I thought.

Sorry to make fun Dave; what happened?

Derek

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Re: Vortex Generators
« Reply #85 on: September 23, 2014, 09:04:31 AM »
...
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Re: Vortex Generators
« Reply #86 on: September 23, 2014, 09:11:08 AM »
Derek I got out early in good air to test them out.  The plus is I do think they make tracking the rounds a touch smoother and easier.  The airplane flew away at the top of the vertical eight which it doesn't normally do even though I got the needle a touch fast.  Not sure the cause.  The BIG change was when the engine cut.  The glide speed and distance cut in half the normal.  I couldn't get over a rut on the field the hay truck left a few weeks ago.  I've done this routinely with this plane until this morning.  It just ran out of steam.  When the gear came out it dropped onto the VGs,  which caught and peeled the sheeting like a banana.

Dave

As an afterthought..these create a certain amount of drag (obviously) and it might simply be that drag keeping the airplane from accelerating down the backsides of the rounds that give the sense of more control.
« Last Edit: September 23, 2014, 10:27:00 AM by Dave_Trible »
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Offline Derek Barry

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Re: Vortex Generators
« Reply #87 on: September 23, 2014, 11:26:48 AM »
Derek I got out early in good air to test them out.  The plus is I do think they make tracking the rounds a touch smoother and easier.  The airplane flew away at the top of the vertical eight which it doesn't normally do even though I got the needle a touch fast.  Not sure the cause.  The BIG change was when the engine cut.  The glide speed and distance cut in half the normal.  I couldn't get over a rut on the field the hay truck left a few weeks ago.  I've done this routinely with this plane until this morning.  It just ran out of steam.  When the gear came out it dropped onto the VGs,  which caught and peeled the sheeting like a banana.

Dave

As an afterthought..these create a certain amount of drag (obviously) and it might simply be that drag keeping the airplane from accelerating down the backsides of the rounds that give the sense of more control.

Orestes told me one time that one of the reasons the Sharks fly like they do is because of all the drag. The cheek and chin cowls, thick rudder, very thick wing and stab all added to this. He said that they were thinking about adding more drag on future designs. The Yak 54 is probably an example of that thinking.

Derek

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Re: Vortex Generators
« Reply #88 on: September 23, 2014, 12:58:11 PM »
Looks like the angle of the VGs is pretty steep.  You might try 15 to 20 degrees.  If the VGs were working, you would have gotten a better lift/drag ratio, hence better glide angle, as Joe did.   

I don't notice any change in L/D on my dogs with VGs.
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Re: Vortex Generators
« Reply #89 on: September 23, 2014, 01:03:35 PM »
Might be Howard.  I set them at 30 which is pretty serious plowing.
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Re: Vortex Generators
« Reply #90 on: September 23, 2014, 06:51:58 PM »
Derek : Dang.. I might just have to run it past Rhiannon and see if we can sweek out another trip ! Id rather see you NOT run VG's any advantage I have over you I need to keep !

Robert ; " To PJ If they make you feel good do it. I will spell it out for you it was a joke " Sure, I knew it was a joke - most of your stuff is.

The vgs on the crashed test plane show here also look a bit far forward - closer to 10 % - Ive found this to increase drag to much - solution in the past was to run 8" pitch - however moving them back fixes this issue 25 - 30 %

Incidently I wanted to get some better data on the VG's drag co-efficient so when the electrics started to run them - I checked with the guy who is running both VG's and Electric in combination and found out there was no additional battery usage and only a 0.05 lap time change.


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.

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Re: Vortex Generators
« Reply #91 on: September 23, 2014, 07:54:05 PM »
Robert had the right idea, if you are going to use them, about building them into the model. That "T" base just durties the air movement over the airfoil. IMHO.

Renders them less efficent because of this. IMHO.
Trump Derangement Syndrome. TDS. 
Avaiojet Derangement Syndrome. ADS.
Amazing how ignorance can get in the way of the learning process.
If you're Trolled, you know you're doing something right.  Alpha Mike Foxtrot. "No one has ever made a difference by being like everyone else."  Marcus Cordeiro, The "Mark of Excellence," you will not be forgotten. "No amount of evidence will ever persuade an idiot."- Mark Twain. I look at the Forum as a place to contribute and make friends, some view it as a Realm where they could be King.   Proverb 11.9  "With his mouth the Godless destroys his neighbor..."  "Perhaps the greatest challenge in modeling is to build a competitive control line stunter that looks like a real airplane." David McCellan, 1980.

Offline Steve Fitton

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Re: Vortex Generators
« Reply #92 on: September 23, 2014, 08:12:19 PM »
 Today must have been a bad day to be flying.  My Dreadnought got torn up in a takeoff accident this morning. Regrettably, VGs cannot be implicated in the crash.
Steve

Offline Randy Cuberly

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Re: Vortex Generators
« Reply #93 on: September 23, 2014, 08:50:56 PM »
One of the most notable things on my Shoestring with Howards VG's was a definite improvement in the glide.
Befor ethe VG's were installed it was an airplane that wone had to be very careful about trying to extend the glide on.  Attempts to do this ususlly ended in a stall and flop onto the wheels from about 6-8 inches above the pavement.
With the VG's installed the glide could be played to make landings easier and ground contact much smoother at a distintly slower speed.

I played with this a lot because this had always been a slightly difficult airplane to land smoothly.  After the VG's were installed it is a piece of cake!

I used only two set of VG's on each wing and really noticed no increased drag or lap time changes.

The Shoestring is a smalish airplane at 620 sq inches and 64 oz. PA65, Pipe.

Randy Cuberly

PS:  Sorry about your poor Broken Airplane Dave!  Get it fixed, and fill in that dam hole!

Randy Cuberly
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Re: Vortex Generators
« Reply #94 on: September 23, 2014, 09:24:25 PM »
Steve sorry about your bad luck.  First day of fall I guess.  Hope you can get it back together.

Randy maybe placement of the VGs played a part.  I had three sets on each wing panel and a set on each stab surface.  They were turned pretty hard to the airflow.  I do know they felt decent in the air rounding bottoms of loops and eights.  I also found it nearly impossible to get any milage from whipping it after the engine cut.  I'm really convinced much of the benefit of these is about adding drag to control speed in certain spots.  If that's the case I'd rather dirty up the fuselage or something to achieve that end.  I even hooked my shirt on one of these carrying the machine which could have torn something loose at a bad moment.  I don't think they are about adding lift-a few more square inches,  more flaps,  more wing thickness  or lighter weight would all achieve that for you.  I don't think they are magic.  I just think it's about drag.  But that's just this man's thought.
The airplane is actually several years old now and was doing the duty to keep the miles off my best .76 ships for next year.  This does finish off the last of my .61 size Desperados.  The bigger ones are better.
The hole?  Well I would but I'll only have the field a few more weeks.  I need a dump truck load at the new field....

Dave
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Offline RC Storick

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Re: Vortex Generators
« Reply #95 on: September 23, 2014, 09:28:38 PM »

Robert ; " To PJ If they make you feel good do it. I will spell it out for you it was a joke " Sure, I knew it was a joke - most of your stuff is.



Better make sure those VG's can hold fuel. So who was the joke on?  I got a great idea why don't you build a website and turn it into the best in the world and I will come there and bash you?
« Last Edit: September 23, 2014, 10:13:58 PM by Robert Storick »
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Offline Chris Wilson

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Re: Vortex Generators
« Reply #96 on: September 23, 2014, 10:37:10 PM »
  ...........what innovation did the Nobler introduce?
    Brett

Since this thread has turned all warm and fuzzy could I please get an answer to the above before it gets locked?
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Re: Vortex Generators
« Reply #97 on: September 23, 2014, 11:20:47 PM »
Since this thread has turned all warm and fuzzy could I please get an answer to the above before it gets locked?

Aft side area. But what do I know everything I do is a joke. So well designed its copied to this day.
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Offline PJ Rowland

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Re: Vortex Generators
« Reply #98 on: September 23, 2014, 11:45:39 PM »
I got a great idea why don't you build a website and turn it into the best in the world and I will come there and bash you?

Bashing you? No that wasn't bashing you, but disrespecting opinions and idea's ranks low on my list of qualities I admire..

Sure thing - Ive got a better idea, why dont you build a take apart plane travel 1/2 way across the world - Qualify for Top 20 Finals and bash me 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.

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Re: Vortex Generators
« Reply #99 on: September 23, 2014, 11:55:17 PM »
Aft side area. But what do I know everything I do is a joke. So well designed its copied to this day.
Thankyou.
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