News:
Support----><----Support




  • August 18, 2018, 04:09:23 AM

Login with username, password and session length

Author Topic: The best stunt airfoil  (Read 7573 times)

Offline RandySmith

  • Administrator
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 13210
  • Welcome to the Stunt Hanger.
    • Aero Products
Re: The best stunt airfoil
« Reply #100 on: March 15, 2018, 10:47:48 AM »
 " Quote from: Bradley Walker on November 16, 2009, 06:23:42 PM
The Bradleymobile uses the Saturn airfoil.  Which is what I call my "thin standard" airfoil.  I believe it is the perfect compromise in the slightly lower aspect ratio T-Rex (I mean Bradleymobile).  I was particularly adamant with the factory that the front of the airfoil must perfect match the plans.  They did not disappoint.

Viewed in CAD all of these airfoils start looking alike, at least from the Hunt and SV series.  Randy's SV airfoils are about 3/32" thicker top and bottom than the Saturn airfoil (if blown up the same chord).  The Saturn airfoil was supposedly derived from Billy Werwage.  The Saturn airfoil looks suspiciously like a Genesi/Legacy/Buccaneer airfoil.  As Brett said, these are all not way off the Imitation airfoil (which is a favorite of mine also).
I would not go thicker than Randy's airfoil.  There is no need.  Just adds weight, drag, etc. "


There is a huge amount I would like to add to this thread about airfoils, I will if I get time to write it, but I would like to quickly correct the above,  To sTart with, not many people know or understand the  SV airfoils, The  SV airfoils  used on many different designs, are  DIFFERENT  and  thinner or thicker, it depends on the size and needs of the stunt ship, in my mind there is  NO ONE airfoil that is right for any plane.
The  StuntCraft  and Stuntcraft Vector , plus the Ryt Flyt  airfoil systems are all adjustable, and can be made thinner, thicker, higher or lower A?R , more or less taper  etc...
All of the above airfoils  have  dozens of  rib stations to pick from   , and you can slide up or down the scale (rib Stations)  to design the wing you want, ie  the VECTOR is ribe station 5 at the root, and  rib 15 at the tip, these can be used to make foam templates , or ALL the ribs in between can be generated by computer
The SV11 based planes I fly are all about 1/8 inch thinner than  the plans  and  kits I sell
The Vector  STARIS , SATONA , SHIKE  airplanes  are smaller thinner  SV wings than the  KATANA or  SV11
The Vector 40 wing is again thinner than the  larger VECTOR and  STARIS   ships
The  Elliptical SV VECTRA  wing  is a  SV airfoil but is different than the above, but the curvature is the same
Then there are the Airfoils in the  NOVA  NOVAR   Classic planes  that are thinner than the SV large ship airfoils, and have about 5% more chord,

About comparison to others like the Cardinal,  my airfoils are as different as night and day, much thinner, high point at a different point, chord, sweep  A/R curvature of the airfoils is different , and there is  NOTHING you can do with blowing up or shrinking  to make them fit

The Hunt airfoils are different than mine, and   do not  fit either, The  SV airfoils  did  not come from  any of these airplanes

I designed the original " GEO BOLT" airfoil/wing that Bill Werwage used in his P-47s , Bill Later tweeked  the airfoil thinning it adding a little more sweepback , but that could have been done on my CAD program and replotted, the P47 plans still fit almost perfectly the  SV wng, it is just now  further down the rib station numbers on the thinner side ie  rib station 6 to 17.
This wing has been used by Bob Gieseke , Frank McMillan, Dave Fitzgerald , Bill Rich, the Barrys , Doug Moon  , and  many dozens all over the world, on Bob Hunts Stunt Flyer video magazine  you can hear and see  Billy pointing to his P-47 and saying  that has a Randy Smith wing in it.
Ted's wing I know from cutting many for people over the past decades is not like mine either, his high point of the airfoil is further forward than mine, I have found that having the high point back, close to where the CG is  works better for  me. So you pay your money and get your choice ! :-)
So bottom line  the  SV wing is  actually 100 of different wings if needed  to be  the similar thing is the  curve of the airfoil , and I have made them from 500 sq inches up to over 750 sq Inches , and dozens of points in between,  This works great for me, and  as  the  have won multiple  World Championships, many NATs wins and top 5 placings all over the World ,  They may not suck too much.

Randy


Offline RandySmith

  • Administrator
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 13210
  • Welcome to the Stunt Hanger.
    • Aero Products
Re: The best stunt airfoil
« Reply #101 on: March 15, 2018, 11:05:53 AM »
  " I would not go thicker than Randy's airfoil.  There is no need.  Just adds weight, drag, etc. "  "

There is  NO  best airfoil !  and NO fits all stuntships airfoil
Here is a Classic problem with statements like this, that  could be  true  or  false, just one example would be  Scott Bair, he designed his ships to use very thick airfoils, because he  wanted excess  parasitic  drag , His  700 sq in , 63 in span ships, with huge round bodies, 3 to 3 1/2 inch spinner  20 in tail moments  and  VERY powerful motors turning up to 16 inch props  weighed in a  42 to 47 ounces !  yes  I said 42 ounces, he was able to fly these in high winds and every condition , and with his designs he flew 6.2 second lap times, with authority , because of the  DRAG he built into the plane.

by the  way his thick wings didn't really add much if any weight, only drag

Airfoils are really complicated on stunt ships, and should not be considered as IDEAL for any plane, you need to take  the entire airplane in mind, and the airfoils should   "fit"  what your doing.  I have formulas and percentages for most all parts of the planes  I use

Randy
« Last Edit: March 15, 2018, 01:22:27 PM by RandySmith »

Offline Dennis Adamisin

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3908
Re: The best stunt airfoil
« Reply #102 on: March 15, 2018, 12:08:31 PM »
WARNING; loooong meandering post to follow...

Been watching this thread with interest.  My fundamental question is how do you define "best"; Highest lift? Lowest drag? Blazing corner while flying like a trainer in level flight?  Only Muhammad Ali could "float like a butterfly AND sting like a bee", so choose wisely!  We have seen credible stunt performance with airfoils ranging from 1/4" thick flat plates (the designs from down under) to really thick semi-symetrical airfoils with huge flaps (Rabe Sea Fury) to laminar flow sections to... you name it.  While it is possible to design a BAD airfoil, I think there are other elements of the aircraft design that overhelm the contribution of the airfoil.  I want to talk about a couple of those details.

GAP SEALS
THANK YOU BRETT for the shout out, presumably about hinge gap seals.  My history on seals is this.  When a preceeding design fell short of expectations, I started over with the first Eclipse (1980) with a full airfoil flaps.  My 7:1 aspect ratio wing used a dead stock NACA 0018 airfoil at the root and a NACA 0021 at the tip modified with the high point moved forward to 25%.  Of course the correct way to build flaps into an airfoil is to use a rolling hinge pocket per Keith Trostle and his excellent Ta-152 & Eagle designs.  However, I figured the structural details were way out of my league.  I resorted to a refined version of a simple hingeline.  I limited the bevel on the flap to allow for a max of 30 degrees movement.  I assumed a hinge gap and then put the absolute minimum bevel (i.e, less than 30 degrees) on the LE of the flap that would allow 30 degrees deflection  The resulting surface gap was actually smaller than many "normal" airplanes I saw on the flight line. I also used a thickish full airfoil on the stab/elevator which ended up about .5" thick at the hingeline, and used the same minimum bevel philosophy there too. The resulting airplane was a complete dog - it would barely manage a 45 degreee round loop. I immediately gave up on the airplane, my brother wanted to mess with it so he took it home.  The NEXT day he invited me to fly it again.  The performance was now astounding.  The difference was taped-over hingelines. The next Eclipse had the seals designed & built in, and I have used them in every airplane I have built since.  BTW, I mentioned the hinge gap seals but no one was listening.

It must have been early 1982 Ted Fancher was in town on a flight layover and we visited.  Ted had recently crashed his new airplane and he said the only thing worse than crashing the new airplane was he had to go back to an older airplane that he hated.  I mentioned my experience with the hinge gap seals - with the usual caveat "what have you got to lose?"  Several weeks later Ted won his first NATs with the gap seals on his formerly doggy airplane.  Along with the performance gain, Ted mentioned that he had removed other trim elements that he had previously used to get the bird to fly less-bad (it had never really flown well before).  In short, the seals gave him a brand new airplane and he started over on trimming.  This just in: Ted is an EXCELLENT builder, but even then it seems the gap seals overcame any inconsistencies he may have had in the hinge gaps, prompting the opinion that gap seals should be used all the time for just that reason.  Ted mentioned the effect gap seals had, and between his NATs Championship & MA column (where he generously mentioned where he heard the idea) everybody was listening now!

Real world experience seems to range from "didn't notice a change" to game changer (Ted & I).  I can rationalize some possible ideas why, but really do not care.  I like the way David Fitzgerald once summed it up: gap seals have all the advantages of adding tail weight with none of the disadvantages.  I just use the seals and move on to bigger issues.


WING TO FLAP AIRFLOW
Regarding the discussion here on getting a smooth airflow on the top surface when the flaps are deflected.  No doubt, my simple flap on the full airfoil without gap seals was nearly the worst scenario possible. Al Rabe's approach certainly looks like the best approach - but what ANGLE of flap deflection do you design for?  Logically it seems prudent to design for the best airflow at max deflection.  However, please note: a airfoil designed for a smooth airflow path with 45 degrees flap will be SUB-OPTIMIZED for every flap deflection less than 45 degrees.  I typically set up my airplanes for 30 degrees or so max deflection, and I never fly up against the stops, so to me designing for a smooth transistion with 15-20 degrees deflection makes the most sense.  I also use slow controls, with CG a bit aft (I think) from what most folks like.  Brett has a funny story about checking the CG on one of my airplanes...

Another building detail may be more important than the airfoil shape: how should we deal with airflow jumping the hinge gap?  It is fashionable to make the front edge of the hingeline (the trailing edge of wing or stabilizer) squared off, and put all the bevel for surface movement on the leading edge of the flaps or elevator.  I suggest this approach is incorrect, for the same reason that using a simple hinge on a thick flap is incorrect.  The hard edge on the trailing edge enables/promotes airflow separation - that we then want to re-attach the airflow on the top of the deflected flap.  I suggest (and my last several airplanes have exhibited) that the trailing edges should be rounded - to enable a smoother transition from the wing, across the gap, and onto the flap.  Yup, I am using 1950's philosphy (plus seals) on hingelines!  However this approach, combined with Rabe inspired airfoils with the proper design point on flap deflection, and gap sealed flaps, SHOULD result in the smoothest airflow transition.  Then do it again on the tail.


A NEW IDEA
My flying buddy Wesley Dick researched flap design and learned that the double slotted flaps should yield more lift with a lower drag penalty than a simple flap.  His personal contribution was to design a simple and robust mechanism that would allow the flaps to deflect in either direction.  The double slotted approach actually tries to take advantage of the gaps to create more lift.  Wes built two of his "Velvet" designs with normal flaps, then 2 with the double slotted flaps.  From the outside of the circle the two airplanes with the double slotted flaps seem to fly better than the two with the simple flaps.  There are several new Velvets under construction so we will get some more/new opinions on the merits of double slotted flaps.  Then SOMEONE is going to try it for the elevator too.


Of course the trailing edges of the flaps and elevators should be as thin and sharp as possible, but that is another discussion..!
Denny Adamisin
Fort Wayne, IN

"The good old days weren't always so good, tomorrow ain't as bad as it seems..."
- Billy Joel

Offline Serge_Krauss

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1134
Re: The best stunt airfoil
« Reply #103 on: March 15, 2018, 10:07:31 PM »
Wes Dick's Flaps.

Offline Brett Buck

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 8856
Re: The best stunt airfoil
« Reply #104 on: March 15, 2018, 10:32:26 PM »
GAP SEALS
THANK YOU BRETT for the shout out, presumably about hinge gap seals. 

    That was another one of those ideas that just made me slap my forehead and go D'OH, why didn't I think of that 20 years ago!  Everything is obvious - once someone else invents it!  Even if the surface were not more effective, it would be worth doing, just because it makes the flow through the gap more consistent (zero is very consistent) compared to having a very small gap that changes by even a few thousandths. It was obvious right from the beginning that the gap was critical, and used to spend hours trying to sand them to the same very small values. My one contribution to the idea is the comment that "no matter how small you make the gap, its still bigger than an air molecule".

   Brett

Offline RandySmith

  • Administrator
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 13210
  • Welcome to the Stunt Hanger.
    • Aero Products
Re: The best stunt airfoil
« Reply #105 on: March 16, 2018, 12:50:31 AM »
I started sealing hinglines in the  early 1970s, I do not now who invented it, but Henry Schutte showed me how to do it with Monocoat , or fabric hinges on painted planes. Monocoat / Solarfilm was much easier, so most of my planes were  covered  with monocoat, and painted on the nose. Monocoat hinges were  strong, easy to make, and completely sealed the flap to wing joint, and  elevators.
Some people today still use that technique with film, and the cloth hinges that cover the entire gap.  I always  hated cloth hinges, so i rarely used them.

Randy

Offline phil c

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1842
Re: The best stunt airfoil
« Reply #106 on: March 16, 2018, 09:31:01 AM »
Thanks Howard and Brett.  I totally missed that debate 5 years ago.  Other problems were in the forefront.  And yes, Brett, CFD is not fool proof, no model is, and careful experimentation such as Igor has done have certainly paid dividends for him and others.

The graph, Howard, is exactly what I was looking for.  It shows what I was thinking.  In flight the behavior of an active-flap stunt airfoil doesn't have the classic, straight line ratio between lift and drag.  It curves to the left of a straight line and makes the top of the curve broader and flatter.  Also, the change extra lift/drag falls off dramatically after 10-15 deg. of flap movement.  Too bad the flaps 20 and flaps 30 airfoils are already well past stall at 15deg. AOA.

That kinda explains what most of us have seen.  A slightly over weight plane, up high into the wind, a gust, and the pilot's frantic attempt to give full control and recover just makes the plane fall almost straight down.  Everyone needs to learn that up high, in trouble, more control is the wrong way to go.  Back off, whip it if you can, and try to get it back down lower where you may be able to recover.  Practice with a clunker that won't wound your ego if it crashes.  Push it near it's limits and practice recovering from minor brushes with disaster before you have to recover from a real one.

None of which change the common wisdom.  Flaps help, quite a bit, especially with the appearance of the plane during maneuvers and weight carrying.  The interplay between all the variables can be tuned to work for most designs.  And mother nature has built a wall between precision and tight turns in the planes and in our reflexes.
phil Cartier

Online Frank Imbriaco

  • 2018 Supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 636
  • At the 69 Willow Grove NATS with J.D. FALCON II
Re: The best stunt airfoil
« Reply #107 on: March 17, 2018, 10:13:23 AM »
It seems as though R/C Pattern flyers embrace gap sealing more so than stunt flyers. Gap sealing prior to first flights always a good idea.

Offline Ken Culbertson

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 503
Re: The best stunt airfoil
« Reply #108 on: May 09, 2018, 01:34:18 PM »
    You still have the problem of validation of the results, and the known limitations (like section characteristics VS finite span effects) of the CFD program. What you actually get in flight could be wildly different from the simulation.

   That certainly seems to help, and in Al's case, is a good example of "guided cut-and-try" with real-life results. Whether he was trying to solve the right problem is certainly open to debate.

    Brett

I know this is an old thread but it's focus is exactly what I am working on today.  Many years ago I used to use a "piano" type hinge using different sizes of aluminum tubing.  Looked great, not too heavy and it completely sealed the the hinge line but they wore out too fast and started to bind under stress so I abandoned them.  The next build of the same design never flew as well and I did not know why.  After listening in on some discussions with Al Rabe about recessed flaps, which he had abandoned at the time, I decided to use them on the next one and I have been using them ever since on flaps as thin as 1/4".  It takes as long to get the flaps and elevator fit perfect as it does to build the rest of the wing but it really looks nice.  What I need to know is whether or not I am actually sealing them.  The LE of the flap is never aft of the wing TE and the pivot point does not produce the "Hump" that Al thought may have been a problem in his tests.  Bottom line - am I wasting my time?

My brother is a well known test pilot (within test pilot circles) and he would completely and emphatically back up your comments on simulation vs. actually flying.

ken

AMA 15382

If it is not broke, don't fix it.

Offline Matt Spencer

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3041
Re: The best stunt airfoil
« Reply #109 on: May 12, 2018, 09:22:50 PM »
Get your ( wifes ) Vacum Cleaner . ( might pay to foam pad the end . Dont Blame Me , if you dont ! )

three guesses !

Put it on one side and bare fingers the other side of the wing / hinge . Try Suck & blow .
Invite SMOKERS ROUND  ( Pref Bob Marleys Cousins  ;D)  give them each a straw .
Put vacume on suck & blow ( variously ) . And try things .

This is probly easyier than a tube , a bag of smoke , and sticking the wing outa the car window at 60 mph .  S?P

-----------------------------------------------------------------------------------------------------------------------------------

If you cut / machined a steel tube in half , lengthwise . For the L E of your flaps .
And maybe machine a radius on a plate , or glue a tube / rod to a thin straight plank ,
youd have TOOLS to fine finish the mating surfaces , wether with fine sandpaper of lapping paste ( Toothpaste ? )

Might save a lot of faffing about .

Offline Ted Fancher

  • 2018 Supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1611
Re: The best stunt airfoil
« Reply #110 on: May 13, 2018, 02:06:58 PM »
Al Rabe used to claim that he designed his airfoils by tracing around his shoes.  If I could walk a mile in that man's shoes -- I'd trace them out first.

Tim,

Didn't that comment originate with Wild Bill Netzeband around the time of his classic "Control line Aerodynamics Made Painless" series back when I was a kid?  As I recall it was something like "X airfoil is ".6X%" better than one drawn by tracing around the sole of my dress shoe"  or something like that.  I think Al was generally more straight forward in developing his with the benefit of a simulated wind-tunnel mounted on a pickup truck and was seldom inclined to speak of such things with the intent to prompt chuckles from his readers.

Ted

Just dug up my old binder full of Netzeband stuff and found the "....Painless" series started in the September/October 1966 issue of American Aircraft Modeler.  I was, sort of, an adult by that time; no longer a kid.  I have most of his "Round and Round" columns from MAN on file as well but it will take some time to go through all of them to see if his "shoe-foil" comment was in those columns.

Offline FLOYD CARTER

  • 2018 Supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3302
    • owner
Re: The best stunt airfoil
« Reply #111 on: May 13, 2018, 02:42:23 PM »
This thread is heavy on graphs, charts, and arcane theory.  That's nice, but I'm wondering how much these finer points really matter in C/L stunt.

I'm an engineer but not much on aero.  So I did the next best thing.  I used the good-old NACA 0025 with flaps just stuck on the back!   Drag is what I wanted, hopefully to prevent speed-up going downward. 

To overcome drag is easy;  use Horsepower.  I tried a Saito 61 4-cycle, and that certainly solved the horsepower question.

How's that for a non-technical response to a highly technical discussion?
"Growing old is easy.
 Staying old is hard"
AMA #796  SAM #188  LSF #020

Offline Ted Fancher

  • 2018 Supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1611
Re: The best stunt airfoil
« Reply #112 on: May 13, 2018, 05:06:16 PM »
Just for the heck of it while trying to debate what is and isn't the "best" stunt airfoil I was reminded of a years ago conversation with Big Art Adamisin shortly after his return from down under as a guest of the many stunt builders and fliers who cling to the planet by flexing their toes into the sod.  Art had been there as their guest to do clinics and some judging.

One of the things he talked most about with me after his return was how surprised he was to have observed, critiqued and judged  one (or perhaps several) Aussies who flew excellent patterns with original designs using flat plate wings (although flapped, IIRC) and were competitive despite what we, in this thread, may have been tempted to describe as perhaps the bottom of the barrel when it comes to describing the "best" stunt airfoil. 

Perhaps Denny Adamisin can throw in some additional info based on more extensive discussions on the subject with his Dad.  Also, if any of our Oz friends have been following this discussion perhaps they can provide some details on who, what, how well and whether the fliers have continued with their no-french curve involved experiments/experiences.  Given the three SH pages of effort and serious debate over maximizing the performance of our stunters through optimization of their primary lifting surface the efficacy of such rudimentary structures would be of great interest.

Ted







Offline Matt Spencer

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3041
Re: The best stunt airfoil
« Reply #113 on: May 13, 2018, 10:29:47 PM »


Philippe Moya .

Ant. Klashnikovs Interpretation . From the Horses Mouth .. ! .



Similar elongated on the 57 in Hurricane was unaffected by Wind , But not flown in bumpy air ,
so couldnt tell you about that , there .


Offline Dennis Adamisin

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3908
Re: The best stunt airfoil
« Reply #114 on: May 15, 2018, 01:36:01 PM »
Ted

Yep, you remember the story about as well as I do.  Dad was in Australia some years back and judged at their Nationals.  There was a guy there (no idea what is name is) with a flat plate stunter powered with a 19 (?) diesel.  Dad said he watched it, was amazed at how well it flew and later asked the guy fly a pattern for him so he could video tape it (I have never seen the tape).  He said the pilot/airplane was never in any danger of winning but he placed.  A post by Russell Bond from down under indicated that pilot placed 8th one year and 4th another year.  Russell said he was the test pilot for one of the flat wing stunters and he was so amazed that he flew it a few more times - as I recall Russell is an enthusiastic supporter of the flat wing concept for a sport-stunter.  I attached an article that I found somewhere (maybe from Russell?) that describes these stunters

Basic layout is a 1/4" flat plate wing with reinforcements at center, some (not all) had full span 1/4" spruce spars embedded in the wing.  The "formula" also included diesel engine (holds RPM under load), and 5 degrees engine offset.  A lot of them were designed to resemble other full stunters.  As you say, it runs counter to basically everything we think we have learned about airfoils, especially the part about LE bluntness.  It MUST be generating a lot of lift via camber change & the trailing edge flaps?  It certainly is not generating lift based on the airfoil contour...

Based on dad's observations from so long ago, and my own curiousity I am building one just to see for myself... (sorry, no diesel)


Denny Adamisin
Fort Wayne, IN

"The good old days weren't always so good, tomorrow ain't as bad as it seems..."
- Billy Joel

Offline Serge_Krauss

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1134
Re: The best stunt airfoil
« Reply #115 on: May 16, 2018, 06:53:45 AM »
I have that article and another related one. One contributor to the 1/2-A Forum here posted a picture of a full-sized slab-wing version of Ted's Imitation. When I have time, I'll search for it in my own files. Apparently the extreme thrust offset is important.

SK

Offline Ken Culbertson

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 503
Re: The best stunt airfoil
« Reply #116 on: May 16, 2018, 07:59:00 AM »
This thread is heavy on graphs, charts, and arcane theory.  That's nice, but I'm wondering how much these finer points really matter in C/L stunt.

I'm an engineer but not much on aero.  So I did the next best thing.  I used the good-old NACA 0025 with flaps just stuck on the back!   Drag is what I wanted, hopefully to prevent speed-up going downward. 

To overcome drag is easy;  use Horsepower.  I tried a Saito 61 4-cycle, and that certainly solved the horsepower question.

How's that for a non-technical response to a highly technical discussion?

I think you may have the answer.  We try and fine tune to 1/4" +- 3'

Guilty as charged

Nice looking ship - Ken
AMA 15382

If it is not broke, don't fix it.

Offline Ted Fancher

  • 2018 Supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1611
Re: The best stunt airfoil
« Reply #117 on: May 16, 2018, 10:11:00 AM »
"snip" 

We try and fine tune to 1/4" +- 3'

"snip"

I love it!

That's my maxim and I'm sticking with it!

Ted

Offline Brett Buck

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 8856
Re: The best stunt airfoil
« Reply #118 on: May 16, 2018, 10:54:29 AM »

How's that for a non-technical response to a highly technical discussion?

       Maybe everyone can get together a list of topics we are allowed to discuss without someone coming along and mocking the effort?  That would be really helpful.

    Brett

Offline Matt Spencer

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3041
Re: The best stunt airfoil
« Reply #119 on: July 08, 2018, 08:46:31 PM »
The STUNT - WIND full size plan , is downloadable from Here ( Hippocket ) :

http://www.hippocketaeronautics.com/hpa_plans/categories.php?cat_id=71&page=5

if your logged in there .



Tags: f2b stunt Airfoil