Differential Flaps

Just thought I would throw this out there for the experts who have tried it or would chalk talk the ins and outs and or positives/negatives. I am going to try it on a profile and thought I might head off some of the trials if some of the knowledge out there would chime in. How much? What to expect? Did Palmer like it or write anything on it.
All I know is when the wings are not level the airplane always turns one way better than the other and if differential will cause the plane to see it both ways then it might be worth trying.
Richard Oliver

Maverick,

Always good to see someone trying to make bad ideas work.

As we all seem to know, Bob Palmer once had a model with this feature. What some of us have not yet forgotten is there was no second model from Bob's shop with differential trickery. I think there is a message there someplace...

I hate to admit this, but my thinking went along similar lines at one time. I was building what came to be known as my "Smoothie On Steroids" and, most unfortunately, had not yet laid aside some of the stuff learned in RC Pattern. One of which was use of a forked pushrod for prodding the elevator into action.

The idea was to use differential at the elevators, simply achieved by using threaded control horns on left and right elevator halves, cranking in more throw on the right.

While this should roll the model to the outside of the circle, I never actually got around to trying it. The model has never flown with anything but equal travel in the elevator halves.

Mainly because about this time I realized I was involved in Stupid Stunt, that until I could at least fake having a serious conversation with P. Walker it might be better to simply copy what others have shown to work and work well. So it is to this day...

The best of luck to you.

>Maverick,
>
>As we all seem to know, Bob Palmer once had a model with
>this feature. What some of us have not yet forgotten is
>there was no second model from Bob's shop with differential
>trickery. I think there is a message there someplace...
>>
>Dan Rutherford

Dan, Palmer's first model with differential flaps was the Thunderbird II. He did indeed have a second design with differential flaps - the Skyscraper which was published in MAN March 1963. The article covers the differential system in great detail and explains design modifications that corrected a problem with the system installed in the Tbird. According to the article, Palmer was quite happy with the results.

I have the magazine article.

No, no, no, no, no, no, no, no, no. this has been discussed many times and the answer doesn't change.

LAST EDITED ON Oct-22-03 AT 08:00 PM (CDT)
 
>No, no, no, no, no, no, no, no, no. this has been discussed
>many times and the answer doesn't change.
>
>Al

Al, what did I miss? I've just re read the article and my answer seems accurate.

Although I don't know the answer, I think I can see a little proof anyways in your above picture. The article says 1963, it is now 2003. 40 years difference and not another example?

Eggy,I would love a copy of that article if you can email it to me.

I seem to remember several other things that were dubbed absolutely to not work, for stunt,
Tuned Pipes
Thick Airfoils
Dihedral
Schnurle Porting
Plastic Tanks
Semi Scale
Automotive paint
It seems that an absolute is proven wrong all the time.
Back to my original question, what was the theory and why will it not work. On paper lots of things are obvious but as I stated when flying a wing that is not level it always turns one way great and the other poor. If this is not the same pricipal as diffirential then what is it. I am not one that takes it on faith that because you say it then it must be so. Give me reasons. Don't talk to me like I'm stupid prove it to me.

Richard Oliver

I've heard mention of Palmer's differential flaps before but never a good explanation of what it involved. I'm "assuming" the horn throw was slightly different on each flap giving one more travel than the other. So:

1) What is the differential flap setup?

2) Why did Palmer try it?

3) Richard has a very valid question. I'm curious also?

>Eggy,I would love a copy of that article if you can email it
>to me.
>
>I seem to remember several other things that were dubbed
>absolutely to not work, for stunt, (snip)
> It seems that an absolute is proven wrong all the time.
>Back to my original question, what was the theory and why
>will it not work. On paper lots of things are obvious but as
>I stated when flying a wing that is not level it always
>turns one way great and the other poor. If this is not the
>same pricipal as diffirential then what is it. I am not one
>that takes it on faith that because you say it then it must
>be so. Give me reasons. Don't talk to me like I'm stupid
>prove it to me.
>
>Richard Oliver

Richard, at the time that these were first tried, the planes were too heavy and the power was too weak. Ways were sought to keep the planes out on the lines. Excessive assymetry was one "innovation" of the day and differential flaps were another stab at the problem. Basically it causes the plane to roll out on the lines whenever it turns. Great idea in theory, but it causes a "wiggle-waggle" in the interections and a lot of banging, with the outboard tip dropping in all the corners. Try adding a tab to the inboard flap on your plane and you will get a little idea of what it will be like with differential flaps.

With the wings waving at all of the spectators during every maneuver that you attempt I can guarantee you that you will not like it. But, go ahead, give it a try. This is not an idea that people have somehow neglected for all these years just waiting to be rediscovered. If anything, we are now using larger outboard flaps and doing the differential thing in reverse.

Hi Dennis

I to, would love a copy of that article, if you don't mind. Email across the big pond will be fine.

>Hi Dennis
>
>I to, would love a copy of that article, if you don't mind.
>Email across the big pond will be fine.
>
>Cheers, Geoff

Just a reminder FYI for everyone. Pretty much any and all articles like this are available from Cap'n Curt at PAMPA products.

>I seem to remember several other things that were dubbed
>absolutely to not work, for stunt,
>Tuned Pipes
>Thick Airfoils
>Dihedral
>Schnurle Porting
>Plastic Tanks
>Semi Scale
>Automotive paint
> It seems that an absolute is proven wrong all the time.

Man, you said a mouthful there brother!!!

You can add 4 cycles to that list too, along with 14 oz plus wing loadings.

For my money, rolling the airplane is always bad. When the airplane is rolled out, due to either a biased wing or too much tip weight, the turn rate will always appear to go away at an equal rate. In fact, the poor turn can manifest itself in such a way that the airplane can even appear to semi-stall.

Of all the things I have tried in my short stunt life, the best sources of line tension are heavier airplanes and raw POWER.

Bob Palmer stated years later that they were for a special set of circumstances. Never again. Go ahead and make a plane with them, then tell us why you'll never do it again!!

The Palmer Hurricane was in that same time frame...does anybody know for a fact that the VECO Hurricane didn't originally come with the Differential Flaps? I can think of several who probably know, but don't want to put you on the spot. Steve

A friend has the kit. I will check. Currell

LAST EDITED ON Oct-23-03 AT 00:41 AM (CDT)
 
Airplanes of the late fifties and sixties tended to use one to two inches of asymmetry. The asymmetry probably didn't hurt the flight characteristics too much but the considerable difference in flap area from asymmetry created quite a bit of outward roll in all maneuvers, both inside and outside. Palmer's differential flaps were in themselves pseudo asymmetry. They also caused an outward roll in all maneuvers with the additional problem that all double flap installations have asymmetry of inboard and outboard flap movement due to the changing angle of the flap pushrod as the bellcrank moves in a segment of a circle. The effect of asymmetry and differential flaps is exactly the same as flying with excessive tip weight. All three, asymmetry, differential and tip weight operate to roll the airplane outward in every maneuver.

The problem was that airplanes of the time had problems with line tension with the advent of slower patterns, and in particular, outside maneuvers. With enough speed, necessary line tension is simply a matter of centrifugal force.

The unrecognized source problem was the effect of gyroscopic precession of the propeller. High pitch rates/sharp corners of newly flapped airplanes, together with slower patterns, was causing enough problems to inspire innovative solutions to problems not fully understood. With normal propeller rotation gyroscopic forces yaw stunt ships inward on outside maneuvers and outward on inside maneuvers. Nobody cared much about the extra tension on insides but the loss of tension on outsides prompted attempts to increase tension overall. THE PROBLEM WAS THE AIRPLANE WAS YAWING. TRYING TO CORRECT A YAW WITH THREE DIFFERENT WAYS TO MAKE AN AIRPLANE ROLL WAS WORKING IN THE WRONG AXIS. You may not care much for movable rudders but, at minimum, they operate in the correct yaw axis. Most of the problem with movable rudders is they require intensive trimming adjustment to obtain optimum operation.

I recognized in the late sixties that excessive asymmetry would cause adverse characteristics in maneuvers. I built the two NATs winning "Sea Furys" with no asymmetry, fully realizing that I would still need one of the big three to create overall line tension while the movable rudder took care of the specific gyroscopic yaw problem. The "Sea Furys" flew well and were exceptionally easy to trim if you didn't worry about using 3oz of tip weight.

When I designed the "Snaggletooth" series of molded Mustangs which actually began with "Easy Two Sugar", I tried to obtain most of the trimming advantages of equal span panels while at the same time reducing the amount of tip weight required. I settled on using a small (1/2") of asymmetry which allowed for the computed difference of lift of the inboard and outboard wings of a tethered airplane. To try to obtain "no asymmetry" characteristics, I widened the tip of the outboard flap to give the inboard and outboard flap approximately equal areas. This somewhat split the difference between large tip weights on "no asymmetry" models and little or no tip weight on models with an inch or more of asymmetry. The combination of reduced asymmetry, modest tip weight and a movable rudder resulted in a very satisfactory solution to line tension problems. Many stunt ships today use some or all of these concepts in their design. Canted tanks and intentional incidence were also introduced in that 1978 article, "Evolution of a Thoroughbred".

For people interested in stunt aerodynamics, design and trimming might check out the following issues of Stunt News.

Mar/Apr 2000 A reprint of the l978 article "Evolution of a Thoroughbred"
Nov/Dec 2001 an article describing the theory and practical use of "The Movable Rudder"
Nov/Dec 2002 a reprint of the 1974 article "Go For Broke", the Sea Fury story

All of these articles contain more detailed information and explanation of tip weight, asymmetry and movable rudders than this post reply can properly address. There is also a wealth of additional information on these and many more topics that can be found in the Stuka Stunt archives. This topic has been discussed at length before. There is an Siren's promice of magical properties in trendy concepts, even those which have been considerably "debunked" decades ago.

Al,

While you and Ted Fancher may differ on the details from time to time, ALL the articles that each of you has written have been extremely well worth reading over and over!! They contain not just innovation, but the reasons for same, and are, for the most part easy to read and comprehend. You both have the ability to communicate your ideas well.

That said, my all-time favorite NATS winning airplane is still that beautiful Sea Fury!

Hi Steve and Currell.

I still have my Veco Hurricane from the early sixties and it did come with the differential flaps. I recall hearing that the kit set up was not correct for whatever reason. I originally flew it with a Johnson 35 Stunt Supreme and it was OK as it was not a lightweight. It was unused for a long time until some years ago when I retrofitted it with a Silver Foxx 40. It now flies very nicely. The additional power helped increase the wiggle-waggle effect of differential flap induced aerodynamics and is kind of fun to watch. Line tension is good but there is an occasional glitch depending which direction the flaps are deflected. Pictures of my Hurricane were in Stunt News about five years ago. Gary Tultz has a Hurricane and has rebuilt it a time or two and I am very sure it has conventional flaps.
As far as answering Mavericks (RO) question about how or why they work, I don't know but can honestly say that anything I use an RO-Jet on stays out on the end of the lines real well without wiggle- waggle!Take care, Don Boka.

The Palmer article on differential flaps was published in MAN, Dec 59 and appeared in Aeromodeller, July 59. These articles showed that the inboard flap would deflect more than the outboard flap. The idea was to increase tension in certain maneuvers like through all of the turns of the hour glass and the verticle eights. He used a 3 inch veco bellcrank with the pushrod from the bellcrank set 19/32" from the pivot. The pushrod to the inboard flap horn was set at 3/4" from the hinge line and to the outboard flap horn at 25/32" from the hinge line. (The elevator horn was 1/2" for a 2 to 3 flap to elevator ratio.)

I tried this on several airplanes I had in the early to mid 60's. I must admit that I did not know much about the pattern at that time and probably would not be able to ascertain any of the subtleties that such a system might provide. Bob Palmer wrote in several articles that he believed the system offered some advantages, even though it worked unfavorabley in certain maneuvers and certain conditions.

I do know that the split horn arrangement is less than an optimal arrangement. I have tried various methods to minimize the flex between the left and right flaps that used split horns. I think the flex between left and right flaps with split horns, regardless how sophisticated the mechanism is to minimize flex, more than negates any advantage that a differential flap arrangement might provide, even if it does. As loads build up on the wing flaps in various maneuvers, there will be different loads on the left and right flaps, the split horns will allow the flaps to deflect asymmetrically because of the different loads (not counting the differential horn geometry). I have never been able to trim any model I have had with split horns to fly the way I felt the airplane should. There is no such thing as a flap horn that is too stiff or a flap that is too stiff.

I have heard some experienced flyers state that actually, they felt the outboard flap with differential flap horns should have the greater movement. Rather than using differential flaps, it seems that the assymetric flaps used on many modern designs are a step in the right direction to balance the assymetric drag, loads, and lift imparted on the flaps as the model goes through the pattern. This is where the flaps typically have equal span, but the outboard tip chord is slightly greater than the inboard tip chord, like that found on the Saturn and the Impact. (There are many others.)

The concept of differential flaps has been around for over 40 years. I am sure it has been tried by more exerienced flyers than I was when I built several models using this idea. I could not tell that the differential flap idea helped. If anything, problems I had with trimming these models were a result of the split horns, and as I said, I tried some fairly elaborate systems to minimize the flex through the control system between the left and right flaps.

Unless there have been some top flyers that have incorporated this idea, like it, continue to use it and keep it their secret, I think that the idea was put to rest some time ago.

Oh, did I mention that split flap horns are a bad idea.

Ron B.
F4Fguy

In the "Skylark" article in M.A.N.in the 60s, Ed Southwick spoke to this. He said that differential flaps would work just fine "if they were reversed" so that the outboard moved more.He was referring to the need for more lift on the outboard wing due to inertia forces caused by tip weight and differential airspeed in the corners.Now,40 years later, almost all top level airplanes use differential of this type in the form of larger outboard flaps.If I'm not mistaken Al has also spoken to this on several occasions.

Keith,I've used them (split horns) successfully by making the torque shaft very short to get stiffness,and actuating them through a relay linkage so there is no differential due to the swing of the pushrod.I also used an inboard bearing so they were not cantilevered,but supported on both sides of each horn.All in all though,as you and Al know,there are much better ways of handling dihedral and/or swept flap hinge lines.

Richard
The next time you are in Dallas look at how Dave Ek has his controls hooked up on his Thunderbird. A hatch on the bottom to access an idler that connects split pushrods to the flaps. very easy to adjust trim without a tab.
Andrew Raney

The Veco Hurricane did have differential flaps with a statement from
Bob Palmer: The VECO Hurricane features an improved hookup system for differential flaps, a torsion removable landing gear, new moments and construction. This is one of the kits that I sell 2 or 3 of a year and the plane flys fine with either a split flap horn or the solid standard horn. Mine was a standard horn installation and had no problems. But I do not do heavy aerobatics so I really don't know which would be the best system to use for patern work.

Over those early years of the T-Bird II, many of us used the differential flaps. It seemed to work but of course, other factors changed the outcome. I have wondered in later years if Bob's original model had a 54 or a 56 inch span. The Flying Models mag with the pic on the cover states 54 inch. Was it the Veco kit version which added the 2 inches and gave us the 56 inch or was Bob's model a 56 inch with SYMETRICAL wings and the differential flaps??

In reallity, if our models have assymetric area flaps, we have differential lift without the mechanical problems of bellcrank rotation.

Thanks Al (Rabe) for much of his "trickery" in overcoming trimming problems.

If we pick out the good points of from all of our past masters and use the ones which work for us, then something has been accomplished.

Happy stunting from OZ.

Dallas Hanna

Dallas Hanna

I was witness last Sunday to a past National Champion being asked by a fellow competitor to evaluate his models trim with a test flight. The former Champion remarked after the flight that it could get by with a little less tip weight. The fellow competitor responded that the model had differential flaps, at which both agreed the models apparent tip drop was rolling caused by the assymetric flap displacement. Essentially nothing could be done about the condition.

>I was witness last Sunday to a past National Champion being
>asked by a fellow competitor to evaluate his models trim
>with a test flight. The former Champion remarked after the
>flight that it could get by with a little less tip weight.
>The fellow competitor responded that the model had
>differential flaps, at which both agreed the models apparent
>tip drop was rolling caused by the assymetric flap
>displacement. Essentially nothing could be done about the
>condition.

Oh, sure it can - I always carry a Zona saw, and all it would take is some carving away on the inboard flap. Or, maybe even better, cut a hatch and move the pushrod up.

I thinks it's blatantly clear that differential flaps, with the inboard moving more to get more line tension, accomplishes it's intended purpose. But all too well. Any time the rate of the maneuvers exceeds the line whip frequency, it will start them whipping, and then you are in a world of hurt as far as precision goes.

A lot of notions to get more line tension work in a static sense, but fail completely in real life transient conditions. Rudder offset, excess tip weight, differential flaps, grossly excessive wing assymetry, and on and on.

Chris,
I don't agree that nothing could be done about the condition. He could try some INBOARD tip weight.

Yes, I guess I should have said nothing could be done at the field with what we had. Of course I didn't know Brett had his saw! Inboard tip weight is a good idea though. As well as trimming the inboard flap.

Chris..

>Yes, I guess I should have said nothing could be done at the
>field with what we had. Of course I didn't know Brett had
>his saw! Inboard tip weight is a good idea though. As well
>as trimming the inboard flap.
>
>Chris..

It would appear to me that adding inboard tip weight to this plane would just add one problem to the other. You need a certain amount of tip weight. Tip weight is not only used for balance (so the outboard wing does not fly high in level flight) but it also translates to tension. Trimming the inboard flap, either narrower or shorter would be the simplest fix.

Oh, PLEASE TED or BRETT

Jump in here and tell Richard exactly what will be happening during hard croner manuvering with differential flaps. Someone, I think it was probably Bob (Palmer) at Brodak's this year told me that making the differential flaps work in reverse would have been better and allowed a plane to carry enough tip weight to maintain good tension.

Hi Richard,

I'm not endorsing it, just posting the article for those who have not seen it. All things being subject to the human factor, I would think most of us "average" modelers would need to be more concerned with building straight and light. I also believe that old ideas should be revisited now and then.
Please, just don't bring back bell bottoms or Disco again!

Here it is:

Here's the pertinent info from the Skyscraper article:

LAST EDITED ON Oct-23-03 AT 09:27 AM (CDT)
 
Hi guys,

Sorry I didn't find this thread a little earlier. I've got a very interesting and, ultimately, funny "rest of the story" to add.

I was privileged to have the original inverted engine T-Bird with differential flaps in my home for about a year as we plotted how to get it back east to the AMA Museum (then in the old Facility in, I think, Reston, VA). Although a bit shop worn it was in pretty decent shape and I spent a little time with some rubbing compound and wax spiffying it up before passing it off to Bob and Mary (Hazle/Gebhart) for the journey back east.

What really caught my attention is that the inboard flap (the one made to move more for the "differential action") had a noticable amount of the trailing edge removed. Hadn't even been repainted -- it was just raw wood showing from root to tip!.

Obviously, at some point Bob had taken to heart his belief that "...it might have worked better if reversed".

Like others, I believe that the combination of the large amount of assymetry along with the differential action resulted in a very unbecoming roll. In order to eliminate it on this plane that had no access for adjustable controls, Bob had simply trimmed away enough of the inboard flap to make up for the fact that it was deflecting too much.

Now you know the rest of the story!

Ted

P.S. I think this airplane is now hanging in the hobby shop at the AMA Museum in Muncie and, unless somebody touched it up, the bare wood trailing edge should be in full evidence.

Did Palmer's triming of the inboard flap go beyond removing the differential or some portion of it? Did he ever explain the results of that experiment, in print, essentially debunking his previous theory. It would have been useful information if presented at the time.

LAST EDITED ON Oct-23-03 AT 09:30 AM (CDT)
 
I see Ted has just posted the "rest of the story" above my post, well, feel free to ignore the info below,it was just a though. I'll leave it, since I know how much Len dislikes people chopping up posts:

Ok, once again, not endorsing this, but rather than all that messing with controls, he says the difference in horns is only 1/32! Not much...If you just HAD to try this, wouldn't it be easier to make the trailing edge of the one flap thicker???? (the pointy end span wise) Not sure by how much to get the proper multiplied ratio, but at least the flaps would retain the original span... It might induce more drag on the outside, kind of like a tip weight effect, hmmm...Unless your wing trailing edge is already a lot thicker than the flaps.

I'm not willing to invest the time trying out unproven stuff, but if someone else wants to play, great, send me the results!

LAST EDITED ON Oct-23-03 AT 02:45 PM (CDT)
 
The "Snaggletooth" series of molded Mustangs used aerodynamically reversed differential flaps in that I described the need for greater width of the outboard flap in the "Evolution" article in 1978 describing a feature of my 1973 Mustang design. Since I failed to label it as being "differential" it seems there will be no acknowledgment that The Mustang was the first airplane to use, explain and publish the advantages of larger outboard flaps, "reverse differential" if you will. At the time, this was a radical departure from the generally accepted practice of using excessive asymmetry (more than 1/2" which gave aerodynamic differential) or the occasional use of Palmer's differential flaps (mechanical differential).

I was unaware of Southwick's comments in his Skylark article. Did he go beyond speculation that Palmer's flaps would work better if reversed? Did Southwick actually use differential flaps in either mechanical or aerodynamic form in any of his designs? If not, then the Mustang was the first. The "Evolution" article and the Sea Fury "Go For Broke" article before it described the "big three" which keeps stunt ships on the end on the lines together with reasons for favoring tip weight. The "Evolution" article also favored tip weight for tension and described aerodynamically differential flaps to allow the substantial use of tip weight. Maybe if Ted or Brett had said it, these concepts would have been more readily accepted. Did Ted or brett expound on stunt aerodynamics in the seventies? According to Jim Pollock, even Palmer now agrees differential flaps would have worked better in reverse. Guys, we have been using reversed differential flaps since the Mustang design in 1973 and "Evolution" article in 1978, All that was missing was the label. The explanation was there and the methodology behind its development and use, all in print.

Not knowing the history I am now finding out what I intended on doing was reverse differential. I was thinking I wanted the outboard wing to move down and drag more. I was also thinking it would be very minor amounts with also being adjustable.
I am surprised though at the comments pointed at making anyone asking a question about something that has already been discussed as waisted time and effort. Even if it was 30 years ago! Not every one has been in Stunt all their lives. I also know that many things that are not supposed to work DO. Brett said it best, as I interpret it, a lot of people think static and can not seem to put things in motion while making calculations. I also found this to be true when I started making motors. Over and over I was told "that does not work" and I found this to be right about 10% of the time.
I also mentioned to Al about maybe a Rabe Rudder type devise in the form of an Aileron. The trim tab used by many could be a moving device in concert with the bellcrank or flap(reversed).
Richard oliver

Aileron tabs would just be another form of differential depending on which aileron you "tabbed".

>Not knowing the history I am now finding out what I intended
>on doing was reverse differential. I was thinking I wanted
>the outboard wing to move down and drag more. I was also
>thinking it would be very minor amounts with also being
>adjustable.
> I am surprised though at the comments pointed at making
>anyone asking a question about something that has already
>been discussed as waisted time and effort. Even if it was 30
>years ago! (snip)

>Richard oliver

Richard, the reverse differential (more movement on the outobard flap) could have a lot of merit, especially if it was adjustable. Today, as mentioned, many designs have more flap area on the outboard flap, accomplishing the same thing. But it would be beneficial to have the area (or amount of throw, as in your case) to be adjustable so the amount could be changed. On Matt's new plane, for instance, we temporarily glued a "wart" to the outboard flap to give it more area. Since he needs to desensitize this, our thinking now is to shorten the inboard flap to give him more outboard throw than what he has. This plane is turning so extremely sharp, that the additional flap that he has on the outboard does not appear to be enough. So, maybe an adjustable tab that could be adjusted in and out at the tip could work, or your idea of adjusting the throw.

And, as to the rediscussion of things already discussed, several people have gotten uptight when a question is raised that was raised six months ago. I, frankly, don't care. Your question wasn't raised, and useful information has been given here. But even if it was raised six months ago, a new group of people read this, and many have already forgotten. I don't care. Ask the question again. Interestingly, we get new answers and updated information each time a question is asked.

Maybe you could use a right-wing-only balance tab. That would thicken the plot.

Howard,

The contents of the pot are thick enough already.

LAST EDITED ON Oct-23-03 AT 07:49 PM (CDT)
 
Maybe we should stop making things adjustable. That way, something would be right sometimes.
I can make one positive comment here: the two models that Bob Palmer flew in Hungary in 1960 were stock Veco 'Thunderbird II' kit models.

>Maybe we should stop making things adjustable. That way,
>something would be right sometimes.
>I can make one positive comment here: the two models that
>Bob Palmer flew in Hungary in 1960 were stock Veco
>'Thunderbird II' kit models.

That was over 40 years ago. The question is, would they even be competitive today?

I was at the nats when Bob Hazel brought BobPalmer,s Thunderbird forthe
upcoming AMA museum(at the time).
We were on it like flies on barbeque, and noted:
1. Model was orange and black:gee I always figured it was red/white.
2. Had 6 bolt Veco 35 (no surprize there)
3. Model had what appeared to be .125 to .250 trimmed off the chord
of the inboard flap. The repair/change had not been painted where the wood was exposed.

Tom Dixon,s T Bird Vsc classic winner had an approx.>750 x 4.00
clear tab on the outboard wing. He said a dec. sq. 8 was impossible
before adding the tab.