Does anybody know why Brett is so sensitive about Strega, Patternmaster and all the derivatives of Big Jim's legacy? Cmon, Brett, lay down your pain finally   

   The most important observation is above - at least the ARF Strega version has a pretty serious defect. It is NOT a "patternmaster" and the differences are significant and make a huge difference. Just looking at the results, I would suggest Phil Granderson knows a lot more about stunt airfoils than whoever drew the ARF Strega plans (which is not that surprising, frankly). In fact, the Brodak website contains this gem:

http://www.brodak.com/files/file/Strega_Building_Wing_Instructions.pdf

   telling you to round of the LE, which probably originated from an SSW post by Gerry Arana from a conversation with Ted and I in 2007.

http://www.clstunt.com/htdocs/dc/dcboard.php?az=show_topic&forum=103&topic_id=280959&mesg_id=280959&listing_type=search

     This fixes it, good on everyone involved, there was an issue, and it was addressed.

   But once you realize that the LE is the problem, you can see how they came up with the other "features" - gigantically thick section and gigantic flaps. The Strega is far from the worst case, the MIG and others from the era had 40% flaps (which is derived from Abbott and von Denhoff, Figure 115). This in attempt to "get more lift" since it didn't work otherwise.

    Of course, fix the LE, and you can run much smaller flaps and a much thinner airfoil, which then permits you to trim the airplane conventionally, instead of trying to manufacture tremendous amounts of line tension and run the CG forward to "get more flap deflection". That was the fatal flaw with Windy's system, and NO ONE competitive ever watched one of those airplanes fly, and then ran off saying "boy I better get the plans for that because I am going to lose otherwise".

    People tell me the Strega plans actually show the LE shaped the same way, which I cannot confirm, since I have never seen the Strega plans. I do know that the Red/Silver Strega that Kent Tysor was flying didn't have that shape to it, and in fact, could not be achieved using the construction of the ARF. It seems to fly just fine and has none of these problems.  I don't know about the original Patternmaster or BJ plans from Big Jim, himself, because I never did more than glance at them over someone else's shoulder one time.

The annoying part is that it has been repeatedly claimed that my buddies copied it or our airplanes are "based on it",  in particular, that the Infinity, Trivial Pursuit, and even the Impact were "patternmaster derivatives". This is absurd from any perspective, but the most annoying is that it seems like we would *bother* copying something that already wasn't competitive. Why rip off Windy when I can rip off Paul/Ted/Billy (whose designs are astronomically more successful)? And in any case, I make absolutely no claims otherwise, freely admitting where I ripped off things and from whom, and where I came up with it myself.  I did rip off Big Jim when it came to solid fuselage construction, which I also freely admit. I probably stole more stuff from Paul than anyone, and anything I might have gotten from Ted and David is kind of hard to pin down, since it was a free collaboration. I would never admit I stole anything from David, just on principle, of course.

     But I also get all sorts of ideas and useful information from these threads, even the ones from beginners and neophytes.

   For a long time, perhaps still, Windy was claiming that the Vector 40 was "based on the proven Profile Cardinal aerodynamics", which I am sure Randy greatly appreciated and is one of the most absurdly and demonstrably false bits of ad copy I have seen in this business.

   It's that kind of stuff that drove everybody crazy about Windy. It was insulting and false, and served to take credit for other people's success. No one gave a flying tinker's damn about what he did on the field and I never had any issue with what he did as a competitor  (although he was a fascinating case study).  He was/probably still is an exceptional stunt competitor, with a record beyond 99.999% of everyone who has ever flown this event. Most people would be absolutely thrilled to be in even *one* Top 5 flyoff, much less dozens.

    The off-field stuff, we "resolved" in private and we each know where each other stands.

     Big Jim, I talked to him for a few minutes one time 34 years ago, seemed like a good guy, and he had some very good observations that advanced the state of the art, in engine operation at least. His design experiments were moderately successful, maybe it didn't lead too far -  but no one knew that when they started and ultimately there's only one way to find out for sure.  I have seen several pretty good-flying Patternmasters - but an ARF Strega is not a Patternmaster and only vaguely related, as far as I can tell.

  I have said the same thing to people in public and private for years. Guys like you come around trying to spin up a controversy every so often, I don't know what you get out of it, but it is something I have come to expect. And besides, I am not the one trying to build a stunt wing with a conformally-mapped Ringmaster airfoil.  We could all be wrong about that, too - but I doubt it.

     Brett

   ...and in fact, could not be achieved using the construction of the ARF.

Thank you for your honesty, Brett - it's a very interesting story.

But actually it's not so difficult to modify a wing of the ARF, one just needs a long metal ruler and a sharp snap-off blade.

Dear friends, dear colleagues,
I would like to have a little request of you, as follows:
I would like to make some statistics of experiments. Please, fly one half inside loop, as tight as you can, and a half outside loop, similarly.
Please, write me/us the achieved minimal heights. It can be estimated very precisely,  and shows far more than analyzing any videos on square /triangle loops' corners' radii.
Will you help me? (and all of us...)
Thanks: Istvan

PS: explanations of the reason later...

What I don’t understand is how a Yatsenko airfoil ties in with this.

Here is a quick analysis of Yatsenko Shark Ellipse airfoil with flaps at 30 degrees. The airfoil can be found in drawings here:
http://discovery-aeromodels.com/en/andrey-yatsenko-shark-ellipse-2-control-line-f2b-model.html

Note: this is NOT an official analysis and I have not been provided with airfoil data from the manufacturer. It is very sketchy, as it is based on a low resolution drawings. You should not make any evaluation or conclusion from these images about true performance of real Yatsenko Shark stunt models.

Here are some drawings and pictures of the Yatsenko Shark airfoil for study.
The drawing was supplied directly by Yatsenko, according to PipeMakerMike.  PDF and JPG are attached.
http://www.clstunt.com/htdocs/dc/dcboard.php?az=show_topic&forum=103&topic_id=311411&mesg_id=311411&page=9&topic_page=2

   Right, there's nothing like a point on that, and the aft section has a good curve to it. And it's negligibly different from a NACA 0020. The small differences shown here make NO difference in the results.

     Brett

Andrey told that he took the airfoil from some real aerobatic plane, I forgot which one, propably Sukhoi.

Im not sure that a good rate of roll is neccesary for F2B Ship . Hence a less blunt Airfoil may be a better proposition .

Andrey’s airfoil (Shark) has the rear surface more flat than Yuriy’s. Andrey told that he took the airfoil from some real aerobatic plane, I forgot which one, propably Sukhoi.

    That is a common thing on full-scale aerobatic airplanes, but it seem to cause extreme control pressure on CL planes - probably for the same reason it improves the aileron effectiveness. Note that the full-scale airplanes also usually have spades or other control-pressure-reducing counterbalances.  Just a little curvature seems to change it completely. I would add that the cambered version (i,e, slice the same thing in about half so it is flat-bottomed) seems to work great for propellors, and for HLG wings.

     The airfoils that I am talking about (exhibiting all the bad characteristics) look like diamond-shaped flat plates with the edges slightly knocked off. A 5th bad characteristic is lots of curvature near the high point. That is necessary if you start with a diamond and knock off the corner formed at the high point. That is literally how I used to modify props, flat facets, then round off the sharp edges, and how you carve/sand HLG wings.

    The ARF Strega only has the diamond shape in the front 1.5" or so (the rear half seems to be fine), presumably explaining why knocking the point off to a still-pretty-sharp 3/6 or 1/4" radius seems to fix it/  The Frankenstunt and many full-scale aerobatic airfoils have all of them. For those we have usually ended up using turbulators taped near the high point to get the air to go "around the corner" that the high point represents. It turned Frankenstunt (which is an Uncle Jimby airplane) from a disaster to merely extremely difficult to fly.

    Bobby Hunt watched Jim fly the Frankenstunt at the NATs, and told him "you have a 200 mph airplane and 100 mph skills".

     Brett

As you can see , it cant be totally hopeless .
' The Story ' is its supposed to voek in da vind , But WHAT KIND of WIND . The Blowy Bumpy rough stuff , We Presume . As In it Dosnt get Blown into the Ground .

    Matt, be advised that I was present for that entire week, and watched every single official flight Bob did very closely. I was also one of the few people still willing to talk to him - briefly.

     I saw him do a practice flight on Monday and it was immediately obvious that he was the favorite - just like the 81 Team Trials, if he was really "on", he was nearly untouchable. He wasn't always "on", and unfortunately for him (and the rest of us) he was unable to tell the difference or accept that other people could tell the difference.

    As it happened, he just blew through the week as expected, and through the first flyoff flight. Then, it got a bit windy, and he started having problems. But so did Ted, with first his engine just fading for reasons we never figured out, then the infamous "bubble gum" flight. Then things got very close, and clearly Ted was flying better. But at the time, the scoring range in the flyoff was very narrow, and once Bob had posted his first flight score (560), it would have taken a big shift of something to catch him. It ended up pretty close but he still won.

 Interestingly he was calling Mike Rogers between flights to try to get some coaching and suggestions over the phone. Mike's Patternmaster was far and away the best example I have seen.

    BTW, I also note that you can see, even in the picture, that the LE is rounded off to the same degree or more than we suggested for the ARF Strega. And to give credit where credit is due, Al Rabe made the same point about pointy LEs in his American Aircraft Modeler column in about 1974, and when we did it more-or-less like Al recommended, it solved the problem.

   As a completely unrelated aside, of all the really great fliers I have been around, including those who are much better in general, I probably try to emulate the way Bob Baron flew at his best (81 TT and 96 NATs) more than anyone  - "clean" and "simple".

     Brett

 

Vitalis,
If I interpret your diagrams correctly, then this Yatsenko airfoil has a nice Cl diagram without bumps up to 8° or 9° AoA.

Indeed. An ascending part of Cl curve is as good as on Igors airfoil and the airfoil can produce a fair amout of lift.

It seems that the kink in the profile created by the deflected flap has no influence??

I think it has. What's so different about Igors airfoil is a top part of Cl curve. It has a very smooth transition from ascending to descending part over high point. That makes Igors airfoil act predictable at AoA higher than optimal.

Maybe it has to do with the hinge construction? I mean the leading edge of the flap itself is a perfect circle. Therefore when deflected there is no sharp corner.

I think you're right. The big radius on LE of the flaps certainly helps to avoid a sharp bump on Cl curve. Is that enough for any possible flight conditions, well I don't know.

I once talked to Yuriy Yatsenko about the logarithmic device like Igor is using it. He mentioned that his airplanes have something similar…. The hinge gap of the flap. He explained that the hinge gap on his design will change with increasing deflection. I checked this on my planes and indeed, the gap changes a little when you deflect the flap.

I think the statement has a sense. There is no doubt that a varying gap does affect flap's performance, the question - exactly how. Unfortunately I have not found a way to reproduce influence of a hinge gap in Javafoil software (still need to learn it) 

I doubt that a Yatsenk plane will have as much as 30° flap deflection in a corner. They usually have a ratio of 1/1.2 to 1/1.3 flap to elevator. 30° Flap would make 36° to 39° elevator. At least it is like that on my planes.

I have a saved message by Peter Germann about Shark where he claims that "... the flap / elevator deflection ratio is approx. 30° flaps at 45° elevator"
Moreover, derivatives of a Shark made by Leonidov that I'v seen had no restriction in deflection at all.


Regards,
Vitalis

What I don’t understand is how a Yatsenko airfoil ties in with this.

Actually ... perfectly :- ))

Take closer look to pictures posted by Vitalis, if you really look what is happenening at 8 deg AoA, you will clearly see hysteresy problem which I methioned in that article. Step on lift curve making tracking problem and the same on moment curve making positive pitching feedback at that angle.
Means wing load must be lower than with airfoil having it at 10 deg AoA (or not having at all) so they will not need to go close or even exceed that point. And also 8 instead of 10 deg AoA making time for corner transition 20% shorter. 

Real life influence is clear and known from real experience, those models fly Ok when light, it means also 20% less resistant in wind and turbulence. They need some extra flight to accomodate for different air density to avoid exceeding those steps, and they lead to oveshooting corners in case of stressy turns.

But I understand you, your model use it, so simply fly it as its is, I happy for that :- )))))

And regarding that gap - well, I am not going to comment its function because I did not analyze, and I will not, because it is making problems with trimming. But what is for sure different, is feedback from hinge moment. My unit limits feedback from hinge moment in corners what allows much easier flying especially in wind. That is second essential property of that unit and I would say most important. That gap cannot do it.

They need some extra flight to accomodate for different air density to avoid exceeding those steps, and they lead to oveshooting corners in case of stressy turns.
[

In some models I did seal the gap with some sort of a lip seal and result was exactly that, especially in turbulent wind.
Anoher bad thing is increased friction, especially in landing glide. Kind of a stick’n slip. L

For sure, because sealed flaps make higher lift coeffient and that makes even lower AoA at low weight ... so it perfectly matchs theory and proofs what I wrote :- ))

Friction is clear if you do it on Yatsenko model, because it has pivot point aft of flap LE, means LE is moving up and down. That is actually nice trick to lower hinge moment. But it is very difficult to do sealing on such hinge construction. If you try it on classic hinges where is no moving on sealing tape, only deflecting, you will not see any friction. .. 10000 times tried :- ))

Just a FWIW comparison, if this old image is clear enough (low res for SSW Forum years ago). I drew up a couple rather "fat" sections: a 23% section with an elliptical l.e. shape to the 30%-chord point and modified NACA aft drawn over an NACA 0023 section (as computed). They are pretty close. The black one is elliptical.

I'm saving this just in case I build a model with wheel pants.

I'll use it for the outline.

CB

Now I would like to share with you a Javafoil analysis of another one airfoil. Actually I'v been highly interested in it, since I built an electric version of a Brodak T-Rex last year. So here it is with a flaps at 30 degrees.
As you can see, Cl curve is linear only at negative AoA and does an abrupt dive at AoA 8 degrees. At the very same time Cd curve jumps up, indicating a strong positive pitching feedback.
Another thing is that the airfoil has the same tendency even with flaps at 15 degrees. Obviously this airfoil is good only for flapless designs, in a case with flaps it is necessary to avoid flight conditions where wing AoA can exceed 8 degrees.

Vitalis

Now I would like to share with you a Javafoil analysis of another one airfoil. Actually I'v been highly interested in it, since I built an electric version of a Brodak T-Rex last year. So here it is with a flaps at 30 degrees.
As you can see, Cl curve is linear only at negative AoA and does an abrupt dive at AoA 8 degrees. At the very same time Cd curve jumps up, indicating a strong positive pitching feedback.
Another thing is that the airfoil has the same tendency even with flaps at 15 degrees. Obviously this airfoil is good only for flapless designs, in a case with flaps it is necessary to avoid flight conditions where wing AoA can exceed 8 degrees.

Vitalis

Just keep AoA less than 8 degrees.  It has plenty of Cl, although not as much as the sealed-flap Shark.

Edited to add some background, although not necessarily applicable to stunt.  In bygone years I flew combat planes with an airfoil with an abrupt stall.  It was a really good airfoil otherwise.  The wings had to be straight, and the controls had to have stops to keep the AoA below stall, but the airplanes worked great.

Now I would like to share with you a Javafoil analysis of another one airfoil. Actually I'v been highly interested in it, since I built an electric version of a Brodak T-Rex last year. So here it is with a flaps at 30 degrees.
As you can see, Cl curve is linear only at negative AoA and does an abrupt dive at AoA 8 degrees. At the very same time Cd curve jumps up, indicating a strong positive pitching feedback.
Another thing is that the airfoil has the same tendency even with flaps at 15 degrees. Obviously this airfoil is good only for flapless designs, in a case with flaps it is necessary to avoid flight conditions where wing AoA can exceed 8 degrees.

Vitalis

Bradley Walker used Bob Hunt's Saturn airfoil when he designed the T-Rex.  https://stunthanger.com/smf/stunt-design/wing-thickness/msg135532/#msg135532
Not trying to be contrary, but it's doubtful that anyone heard of Bob Hunt's Saturn having any big troubles turning or falling out of the sky due to AoA. 

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.

I would suspect the Saturn airfoil is similar to PT airfoil also.

Javafoil and cfd is useful.... but be careful .... it may lead you to sniffing a brick wall

Brett,

Could you please quit your job and US, and move in Switzerland to work for high end/luxury watch industry? L

I really enjoy when Brett Buck adds to conversations.  He really gets people wound up.  Remember it's for fun! 

I'v had an electric T-Rex for more than a year now, and spent all last year tinkering with it. The weight is 1830g (64,5 oz) RTF. Аll in all I'v flown approx 150 flights. That's not a lot, but still enough to come with some thoughts.
So here I going to speak from my own little experiece.
It is not a bad design, but certainly has its flaws. One of those being a wing. I did not succeed to get a crisp corner out of it, and that was most obvious on triangles - way too big radius. I tried to play with elevator/flap travel, but it did not become any better whatever I did. Just a force on a handle increased tremendously to a level, that a few times I hurt my wrist and literraly I was unable to continue any stunt for the rest of a flight. So I set elevators back anf forgot that.
Another flaw - the plane doesn't have enought stability, at least to my requirements. I'v made a new stab from a scratch with a larger area and sharp LE, also moved it back for a half of an inch. That fixed stability issue quite a lot, but still not to the level of my old stunt plane. But that's not the case here.
Now Javafoil opened my I eyes a little bit, at least I can see thats going on with the airfoil. So I think that was not a bad idea to invest my time in learning it. I am also going to fly my T-Rex this spring (it's my first electric ship also), I will try to make some more adjustments, since I'v had more knowledges through the winter time.

  Don't get me wrong, I am not trying to start anything, but there are about 1000 reasons that your airplane doesn't fly the way you want that I would look into before some obscure hypothetical property of the airfoil. In any case, the airfoil you modeled in Javafoil is not the one you actually have, and it's neither two-dimensional, nor the same when you look at it in 3 dimensions. For instance, you will get potentially relevant change depending on how tight the covering is shrunk, and it is definitely different between ribs compared to where it has ribs. In fact, guessing at what causes your unexpected separation in the math model, billowing or sunk-in covering would tend to DRASTICALLY alter the separation point. Have a few wrinkles in the right place, congratulations, you have turbulators.   As far as I can tell, you are not modeling the hinge line flow at all, that, too would potentially have dramatic effects on exactly the sort of hypothetical problems you are having, and how they manifest themselves in real life. That's the problem with CFD modeling without the approrpriate controls or validation, and in this case there are very obvious potential flaws with it that you could easily predict.

   I seem to recall the largest airplane manufacturer in the world designing a wing entirely using CFD, then finding the wing had a higher CL with the wing LE slats stowed than with them deployed when they actually flew the airplane. I also seem to recall people trying to do CFD models on stunt planes to prove that turbulators were worthless - even though we managed to get Ted's airplane through a NATs in the rain by taping 0.018 flying lines to the surface. Now, some of the same people have found no theoretical value for vortex generators that nonetheless were last seen with airplanes festooned with them, the bigger the better.

     It's entirely within the realm of possibility that you have indeed found something that causes a problem. It's entirely possible that I will get hit by a meteorite on my way to pick up my Powerball winnings with my new girlfriend Cindy Crawford. But after reading back through the thread, I am even more inclined to suspect Frank's dog drawing is in fact on point. I would add that Frank was, among other things, a simulation expert for the Space Shuttle and I ran about 1500 simulations of a highly non-linear and moderately complex system 2 weeks ago, and spent most of the last week validating it with flight data. Mine had no air involved, but the more experience you have, the less you are willing to take simulations as unvarnished truth without validation.

     The T-Rex is a decent and reasonably conservative design, if it doesn't fly well, we can probably help you get it to work.

    Brett

Brett, I completely agree with you... No simulation should be trusted until it got validated in real life. And I agree that the means of simulation we have (javafoil) can't simulate all aspects of a F2B ship.

Writing this right now I feel rather stupid for starting this thread in the first place. Or maybe not?
Wouldn't a airfoil that is superior to another in theore be superior in real life as well? What I mean is, we make the same "mistakes" when calculating an airfoil for both, the superior and the other airfoil.

I think it is fascinating where this thread went so far.
It is also very fascinating to read the different theories. So many different concepts and they all seem to work. Beringer, Yatsenko, Burger, Windy..... All rather different but all seem to work.

So maybe there is a chance that the Wortmann airfoil in question will work as well!
The designer claims to have built a test plane last year and that seems to work just fine for him.

Mr. Wadle, not a bad question at all …. We are all still looking for the best airfoil shape, everyone thinks there might be something better out there.  We have learned some things that are good and some things not to do, like building to a ¼ inch square le spar.
One of the biggest PA regrets through the years that I have, is not following up on the wind tunnel tests that were performed in the low speed tunnel at the University of Illinois at Urbana (UIUC) by graduate students of Dr. Michael Selig.  Selig was/is a sailplane flyer and was involved in low speed wind tunnel testing during his education.  He put out a request for models to test in the tunnel.  All you had to do was build a model to the tunnel specs and it would be tested. 
I wanted to test a Fancher type airfoil with flaps, a Rabe type airfoil with flaps, a Nobler, etc.  , but I never got around to getting my project off the ground.  The Selig project resulted in several volumes of data through the years.
http://m-selig.ae.illinois.edu/uiuc_lsat.html
 Many sailplane airfoils were tested.  The nearest airfoils to a stuntship wing were in some of the later tests of several RC trainer wings.  Two of these tests were for the Ultra-Sport 1000 and the Trainer 60 airfoils.
The results of these tests, once again real wind tunnel measurements at Reynolds numbers appropriate to PA aerodynamics, turned out to be fruitful for us.  Similar thickness airfoils (UltraSport and Trainer)with different leading edge radius, the two airfoil tests do clearly show an earlier stall of the sharper leading edge section.  Although I haven’t done it, it might be interesting to load these two sections into JavaFoil as a comparison of numerical analysis to windtunnel results.  Attached are the Selig results for these two airfoils at a Re = 500,000. 

Frank Wadle,
as Frank Williams suggested, open http://m-selig.ae.illinois.edu/uiuc_lsat.html
On that website, you can download the thesis of  Williamson, G.A. Experimental Wind Tunnel Study of Airfoils with Large Flap Deflections at Low Reynolds Numbers.

There you could look at the data of airfoil W1015, with flap deviation up to 45°, at Re=400 000. CL up to 1,9!

Regards,
Wolfgang

It would be really nice if one of the X-Foil junkies would run the airfoils needed to get a true picture of what actually happens on a stunt plane.- 0 flap at 0 AOA, taking into account that the airfoil with a deflected flap has an angle of attack from the leading edge to the trailing edge of the flap.  A sequence of, say, 0 AOA 0 flap, 5 deg airfoil angle 10 deg deflection, 10 deg airfoil angle 20 deg flap, 15 deg airfoil angle 30 deg flap, maybe 20 deg airfoil 40deg flap.  Plot the results against the combined airfoil/flap AOA at each deflection.  I believe that would give a better idea of what is actually going on.

http://www.clstunt.com/htdocs/dc/dcboard.php?az=show_topic&forum=103&topic_id=371054&sub_topic_id=371056&mesg_id=&page=#371073  Start with post 42.  Defining the angle of attack as being from the LE of the wing to the TE of the flap is not very useful and not done by folks who use such data.  I did it for Ted's amusement in post 78.

 " 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