Best Stunt Ship

[Motorman]

blank

[Clint Ormosen]

The latter.

[wwwarbird]

 You may want to check Clint's "Forum Realities" post on this one.

[dankar]

Right on Ty !

[Howard Rush]

So, after decades of stunt flying have we identified the best design, is there a formula for surface area/moment arm ect. or, is it one of those things where a wide variety of things will work just as well?

We're still looking for the best combination, but I don't think the "numbers" are a particularly useful way to look at the problem.  People use the same concept to pick women.  It leaves out some parameters.

[Brett Buck]

So, after decades of stunt flying have we identified the best design, is there a formula for surface area/moment arm ect. or, is it one of those things where a wide variety of things will work just as well?

     There is a fairly narrow range of parameters that have been arrived at that appears to provide the best performance. Look at some currently competitive airplanes  (SV-11 and similar airplanes, Impact, Trivial Pursuit, Geobolt, etc) and you will see that they are very similar. The arguments you see are over very minor details - no one is doing anything radically different from anyone else. All of these ideas were arrived at in the early/mid-90s to take advantage of superior power available.

   A wide variety of things will NOT work just as well, depending on your definition of "wide". I consider all the current competitive airplanes are in a very narrow range of variation. There are no exotic designs, canards, biplanes, etc. The biggest differences are things like (for example) the aspect ratio of the stabilizer, I think the SV-11 and similar have too high an aspect ratio tail, Randy et. al would undoubtedly argue that mine is too low and either one could be right. But we are talking the difference between a 6:1 and 4.5:1, we aren't debating to any degree what the far more important factors are, like the tail moment or the tail volume coefficient, almost all of them are within a few inches and within a very narrow range of about .4 to .5 or so. Everything else is like that too, we don't discuss the gross numbers anymore because we all agree.

      One the airplane design side, there have been about two important changes since the Nobler was designed in ~1951 - more tail volume and thicker/blunter wings. In *60* years that's about it. There are a bunch of details that make noticable difference but in terms of raw, big-picture design numbers, there isn't any significant debate on what works.

    The details of the engine/motor setup make far more difference than the airplane design, and there have far bigger and more recent changes.

     Brett

[Tim Wescott]

So, after decades of stunt flying have we identified the best design, is there a formula for surface area/moment arm ect. or, is it one of those things where a wide variety of things will work just as well?

The "Moitle".  But then those sneaks at the AMA went and changed the rules so it's not competitive any more.

[Brett Buck]

The "Moitle".  But then those sneaks at the AMA went and changed the rules so it's not competitive any more.

   You can build a Moitle anyway you want, fly it any way you want, and as far as I know there are no rules that make it impractical. Good luck going up against Paul Walker.

    Brett

[Dave_Trible]

So, after decades of stunt flying have we identified the best design, is there a formula for surface area/moment arm ect. or, is it one of those things where a wide variety of things will work just as well?

Thanks,
MM

For an interesting exercise take the Shark 45 plans and compare to todays designs.  Add a bit more tail area,  modern adjustables and a piped .51-.65 and you'll be pretty competitive.  Mostly I think its about grooming a design to fit your style and liking.

Dave

I still need to check out Howard's dating service.

[Allan Perret]

    But we are talking the difference between a 6:1 and 4.5:1, we aren't debating to any degree what the far more important factors are, like the tail moment or the tail volume coefficient, almost all of them are within a few inches and within a very narrow range of about .4 to .5 or so.

What is the definition / formula of the "tail volume coefficient" ? 
Mostly trying to understand if this measurement takes into account the tail moment arm, or is just a ratio of wing and tail areas 

[Howard Rush]

Here's a good writeup: http://www.eaa62.org/technotes/tail.htm .  It does take into account the tail moment arm and divides it by wing mean aerodynamic chord to make it nondimensional.  Tail volume coefficient is still a little too simplistic: it doesn't take aspect ratios into account, even though they are easy to measure.

[MarcusCordeiro]

I think this is kind like trying to get the best player in some ball sport, or the best driver ever.
There are many issues, but it all comes down to your favorite.
Maybe some like the Nobler, but will not tell, it's such an old ship, isn't it?
I'm about to get started on a Thundergazer, 'cause I liked he looks, and of course, it's a very good model.
But my favorite, and with a bit of luck, my next year's main building goal is Bill Simmons's Rogue...

Which is better

'69 454 Camaro Rs or '69 429 Boss Mustang?
2012 Camaro or 2012 Mustang?
I guess it depends on the way you like to drive.

Me? '69 Plymoth Roadrunner superbird...

Marcus

[Douglas Ames]

Which is better

'69 454 Camaro Rs or '69 429 Boss Mustang?
2012 Camaro or 2012 Mustang?
I guess it depends on the way you like to drive.

Me? '69 Plymoth Roadrunner superbird...

Marcus

Big Block musclecars from the past handled like pigs and braked even worse. The Boss 302 and Small block Z28 were decent for their time.

I currently own a 207 Shelby GT500 which blows away any past era Mustang.

Like others have said, "Best Stunt plane" is relative to the era  it was designed and flown.

[Allan Perret]

Here's a good writeup: http://www.eaa62.org/technotes/tail.htm .  It does take into account the tail moment arm and divides it by wing mean aerodynamic chord to make it nondimensional.  Tail volume coefficient is still a little too simplistic: it doesn't take aspect ratios into account, even though they are easy to measure.

Thanks for the link Howard.  Most interesting thing I learned it that TVC has application to all planes.  
For some reason I was thinking it was unique to c/l stunt because of the non-standard flap functioning.  
So what are some typical TVC numbers that work good for c/l stunt ?  

Also,  from the link  "SH = horizontal tail area"  ,   this is total area of stab plus elevator, right ?

[Don Hutchinson AMA5402]

Regarding "Moitle", she was designed and flown in 1944 and there were no stunt rules back then. The first itieration of stunt rules was used at the 1946 Wichita Nats and they were nothing at all like the OTS rules we fly to today. "Moitle' by the way is a very nice flying OTS airplane, leastways my first one ten years ago was, I now have another in the hopper for a spark ignition Torp 32, hope it is the same!. I am sure "Moitle" was the first model to use a symetrical airfoil and able to do outside maneuvers. Francis Reynolds, the designer was a very bright guy!

[Tim Wescott]

Modern stunt ships seem to favor a TVC of 0.5 or so.

But if it were just TVC, then a teeny tail on a long stick would fly just as well as a huge tail on a short moment arm -- but you don't see any long-moment, little-tailed stunters out there.  So there's got to be more to it than TVC (and even, for that matter, wing and tail aspect ratios).

[Tim Wescott]

Regarding "Moitle", she was designed and flown in 1944 and there were no stunt rules back then. The first itieration of stunt rules was used at the 1946 Wichita Nats and they were nothing at all like the OTS rules we fly to today. "Moitle' by the way is a very nice flying OTS airplane, leastways my first one ten years ago was, I now have another in the hopper for a spark ignition Torp 32, hope it is the same!. I am sure "Moitle" was the first model to use a symetrical airfoil and able to do outside maneuvers. Francis Reynolds, the designer was a very bright guy!

Hah!  You make my point!  The ultimate ship arrived early, and then two years later they went and made rules just because of it!

(Moitle is on my long "to build" list -- but at the rate I build, the sun just may go out before I get around to it).

Sigh. My comments were a joke! I am thinking it would be a lot easier all the way 'round if youse guys would elevate your appreciation of humor, 'cos there is no way I will reduce myself to using those faggoty smiley things!

(Quoted because I couldn't say it better.  And besides, if I just repeated it, Dan would accuse me of copyright infringement)

[Howard Rush]

But if it were just TVC, then a teeny tail on a long stick would fly just as well as a huge tail on a short moment arm -- but you don't see any long-moment, little-tailed stunters out there.  So there's got to be more to it than TVC (and even, for that matter, wing and tail aspect ratios).

Yes, there is, and I should have mentioned the other stuff.  The first 9 items in the list of 10 in post 36 of http://stunthanger.com/smf/index.php?topic=20427.msg199505#msg199505 are some of the other things. 

[MarcusCordeiro]

Big Block musclecars from the past handled like pigs and braked even worse. The Boss 302 and Small block Z28 were decent for their time.

I currently own a 207 Shelby GT500 which blows away any past era Mustang.

Like others have said, "Best Stunt plane" is relative to the era  it was designed and flown.

That's my point exactly...
They were more fun to drive, taking to the limit all the time...


marcus

[Howard Rush]

Also,  from the link  "SH = horizontal tail area"  ,   this is total area of stab plus elevator, right ?

Yes, and the wing includes the flaps.

[wwwarbird]

Tail volume coefficient is still a little too simplistic: it doesn't take aspect ratios into account, even though they are easy to measure.

 Howard,

 I believe this concept has also been used to pick women, but again leaves out some parameters.

[Bob Hunt]

The question was, what is the "Best Stunt Ship?"

That's simple: Mine! 

Bob Hunt

[Howard Rush]

I believe this concept has also been used to pick women, but again leaves out some parameters.

Reminds me.  I need a couple spinners.

[Ted Fancher]

Here's a good writeup: http://www.eaa62.org/technotes/tail.htm .  It does take into account the tail moment arm and divides it by wing mean aerodynamic chord to make it nondimensional.  Tail volume coefficient is still a little too simplistic: it doesn't take aspect ratios into account, even though they are easy to measure.

Howard's EAA link is a dandy one that may have been overlooked by some.  Not only does it give a good derivation of tail volumes but it also discusses the various "whys" of big versus small...a matter of no little discussion on these fora for the last decade or so.  I thought I'd cut and paste some of the pertinent pluses and minuses.  He also has a good picture of a pictorial method of determining the MAC (Mean Aerodynamic Chord) of a surface (yes, by the way a wing should always be considered including flaps and the tail including elevators when doing such things).  I've settled on using the phrase "average chord" vice MAC in my several thousand pages of blather about such things because it doesn't require much explanation and for any reasonable surface planform suitable for stunt will get the user into the right "ballpark" for the sorts of bench trimming we do to set up a new ship...usually refined by flight testing but that testing can be minimized greatly by paying attention to tail volume coefficient and the appropriate CG to accompany it.  Again, this sort of thing is the basis for my "wet finger in the air" method for determining an initial CG location when setting up for first flights.  It ain't rocket science but will get you in very close proximity of optimum and is pretty much guaranteed not to get you in trouble.  That method is simply dividing the area of the tail by the area of the wing, getting a 'percentage' and then locating the CG at that percentage aft of the MAC/average chord.  Tiny tails, tiny percentage aft.  Bigger tails, greater percentage aft (and reduced loads on the controls...see the writer's comments early in the following)

Ted

Here's the outtakes from the EAA document.  I've highlighted in green the "positive comments from our stunt perspective" and used red to highlight why we shouldn't let our tails get too small.  The purple is simply to  highlight the discussion of determining MAC which was accompanied in the link with a fine diagram.  That same diagram (or a reasonable replica) was included in my Model Aviation construction article for the Imitation that is viewable through the AMA web site if you want to go there.  Otherwise simply click on Howard's link.

Edited p.s.:  I did note when reviewing my post that the author (Stan Hall, my apologies for ripping off his stuff without crediting him) did address aspect ratio in passing in his brief discussion of regaining a stable setup by increasing tail area rather than moving the CG forward.  He suggests adding span because higher aspect ratios are more efficient (produce more lift per unit of drag when doing their jobs).  This may or may not be the best approach for a stunt ship, by the way, as Brett mentioned earlier.


"How Big The Tail
by
Stan Hall
Technical Advisor, Engineering, EAA Chapter
 62

In design, sizing the tail is a very subjective process, one which involves often conflicting requirements of c.g. range, stability, control and desired aircraft handling properties. Small tails tend to limit the permissible c.g.travel and thus yield low static stability, but on the plus side, yield low stick (or pedal) forces and low drag. Conversely, low-stability airplanes are harder to fly on instruments than higher-stability aircraft. For single-seat airplanes, however, the pluses of small tails sometimes outweigh the minuses. This is, however, the exception, not the rule.

On the other hand, airplanes carrying large tails provide a wider permissible c.g. range and tend to be more stable and thus easier to fly on instruments - but are often heavier on the controls, (depending on where the c.g. is). Large tails also produce more drag.

How, then, does a designer decide how big to make the tail on his new project? Unless he is a good mathematician and simply loves complicated arithmetic he will find what is known as the Tail Volume Coefficient much simpler to use, yet very effective.

The Tail Volume Coefficient is denoted by the letter V and is determined by one equation for the horizontal tail and another, quite similar one, for the vertical tail. The Tail Volume Coefficients relate the area of the surface, the distance that area is from the aircraft's c.g., the wing area, the mean aerodynamic wing chord and the wing span. Aircraft having the same Volume Coefficients tend to have similar static stability characteristics. Knowing this eases the design process.

In equation form Horizontal Tail Volume Coefficient (VH) looks like this.
VH = SH x LH / SW x m.a.c.
where SH = horizontal tail area, LH = distance from tail's aerodynamic center (more of which later) to the aircraft c.g., SW = wing area and m.a.c = the mean aerodynamic chord (more of this later, too)



Shown below is a sketch of how to determine the mean aerodynamic chord (m.a.c.) and the position of the aerodynamic center (a.c.) by graphical means. While the results are approximate they are considered accurate enough for the purposes discussed here.

Let me close by reciting a couple of old engineering bromides. (1) It is easy to design a tail that is too small. It is difficult to design one that is too large. (2) Big tails are more user friendly than small ones. Hint: Tailheaviness can often be cured simply by the addition of horizontal tail area. Adding it by increasing the tail span is more effective than adding it elsewhere because the tail aspect ratio is then increased, making it more efficient."[/color]
©2000-2002 Stan Hall
Questions and Feedback can be sent to the webmaster

[Crist Rigotti]

The question was, what is the "Best Stunt Ship?"

That's simple: Mine! 

Bob Hunt

You beat me to it! 

[Crist Rigotti]

Reminds me.  I need a couple spinners.

Now that's funny!   

[Clint Ormosen]

Which is better

'69 454 Camaro Rs or '69 429 Boss Mustang?

A '69 454 Camero?
I don't think there is one.

[RandySmith]

A '69 454 Camero?
I don't think there is one.

Biggest engine they put in was 396,  except for the very few COPOs that some had 427

R

[Clint Ormosen]

Biggest engine they put in was 396,  except for the very few COPOs that some had 427

R

Right. Also some 427 Yenko Cameros, but those were dealer modified. Not factory.

[Larry Fernandez]

Which is better

'69 454 Camaro Rs or '69 429 Boss Mustang?
2012 Camaro or 2012 Mustang?
I guess it depends on the way you like to drive.

Me? '69 Plymoth Roadrunner superbird...

Marcus
[/quote]

Chevy didn't put 454's in camaros in 1969.

Larry Fernandez, Buttafucco Stunt Team

[Larry Fernandez]

Right. Also some 427 Yenko Cameros, but those were dealer modified. Not factory.

Actually, the 427's were installed at the factory. not all COPO cars were Yenko's.
Yenko took delivery of a few Copo 425 horse 427 Camaros (L-72), tweeked them a bit added the Yenko badging.
He also did some Chevelles, Novas, and Corvairs.
Any of these cars today, if properly restored, are worth well over 200K
I saw a Yenko Nova sell for 750K at the Mecum Auction a few months back.

Larry, Buttafucco Stunt Team

[wwwarbird]

Reminds me.  I need a couple spinners.

 

[Igor Burger]

Guys, you must remember that tail volume coefficient is good parameter of flat flying airplanes, but it is not enough for stunt airplanes. The reason is, that while normal airplanes has angle of attack on tail very close to constant (the same like wing), stunt airplanes fly radiuses, so angle of attack on tail is variable and can be +/- 20 degrees on our models. This makes difference between small tail on large arm and large tail on small arm. The difference is in effectiveness of airfoil of deflected elevator.

While short tail solution tends to have stronger and stronger pitching effect during tighter and tighter turn, long tail solution loses its effectiveness as model enters tight turn. So while short models can do tight but not so well controllable turns (so they need to be little nose heavy) long tails will show good initial movement but in reality they do not do 90deg turn so well and they need little more back CG.

So it is necessary first to find proper tail length which can keep initial moment to corner and effectiveness during turn in good balance (so the pilot can do clean and tight corner) and only then to play with area of the tail.

And second thing - larger tail volume can allow back CG, but too large tail and too back CG is also not good, especially if CG goes close or back of 25% of MAC. It is because too back CG can pust tail to produce positive lift, while maneuvering needs negative lift. Theoretically in clean air and perfect airfoils does not matter, but that transition from positive to negative lift in tiny inputs from pilot in level flight cannot do anything positive, I think it simply must lead to hunting, because quaily of flow is quicly changing in such conditions and so also microscopis change of deflection leads to large effect on such large area. My last model has tail area far over 25% of wing area (close to 30%) and CG is still front of 20%. However that large tail allows anything from 15 till 25% without too much difference :- ))

[Howard Rush]

So it is necessary first to find proper tail length which can keep initial moment to corner and effectiveness during turn in good balance (so the pilot can do clean and tight corner) and only then to play with area of the tail.

Does the logarithmic flap linkage allow you to use a longer tail?

[MarcusCordeiro]

Guys

You are right, my bad here...
The 454 came in the Chevelle and Corvette.
The Camaro got the 396.
Anyway those cars were 100% muscle.
I got confused because one acquaintance is building a 69 Camaro with a fuel injected 454, and all the works
Blue and white. Mean machine..


Marcus

[Igor Burger]

No, it has nothing to do with flaps ... at least if I do not take its effect on aif flow deflection to the formula. If you want analyze what I wrote, you make loft curves for both configurations with deflected elevator before trasition to circular path and in the circular path. You will see that short and long tails are on different points.

[Igor Burger]

I do not have coordinates of real tail airfoil, but here is NACA 0007 with 40% flap deflected to 30 degrees.

You can see that flap instantly deflected to 30 degrees before corner will cause separation. Negative angle of attack 5 degrees will push it to its maximum and negative angle 10 degrees or more again looses its effectiveness because low AoA.

So while short tail very close to wing when AoA of tail is only -5 degrees because of circular flow, will make tail more effective and it will want to do tight turns, tighter than the effect before model enters circular path. While too long tails will not be able to keep entered path because of too small deflection. Both can confuse pilot.

Well ... it is simplified, because I do not count AoA of wing, flap effect on air direction and deflection is also not really instant, but the main effect is clear from that description I thing.

BTW some people asked me why I use such small movable elevator. I think picture shows it well :- ))) .. just not to allow slying over critical AoA before corner. 

[Avaiojet]

Is this design, Lou Wolgast's 'Pentastar,' a good performing model?

The kit is offered in two sizes.

Charles

[Bill Morell]

Is this design, Lou Wolgast's 'Pentastar,' a good performing model?

The kit is offered in two sizes.

Charles

No, doesn't fly for s h i t. Eric traditionally kits planes based on lack of performance.................

[Avaiojet]

No, doesn't fly for s h i t. Eric traditionally kits planes based on lack of performance.................

Bill,

Thanks for the humor.

Are you making fun of my dreams?   

Didn't know you could say  s h i t  on the Forum? Usually it looks like this S#*t.

IMHO, I think Lou Wolgast's 'Pentastar,' is the most attractive stunt model.

I googled 'Pentastar,' be interesting to know how the name came about?

Bill, thanks again for the humor!!

Charles

[Eric Viglione]

I wouldn't discount the psychological effects here. Some of us (should probably read most, myself included) usually convince ourselves that the best stunt ship in the world is the new one gassing off in the paint stand.

This effect is so strong that when we go put the maiden flight on this new bird, that we dare to put a full pattern on it just for bragging rights or because we mentally mask all the planes real inadequacieses.

Funny how a few flying sessions later, the posts start to roll in, asking trim questions about planes that "flew perfect, right of the bench".

I see this work in reverse too. Get to a contest, especially a pressure cooker like the Nat's, and oh, my world beater is flying like cr@p!  When in reality, its is flying the same as it always has, but our adrenaline is so high that we are super sensitized to every little nuance of what the plane is doing.

After a full week of intense flying at the Nat's, I once retrimmed my plane so that when I got home and took a month off of flying and finally got back to fly it, it felt extremely sensitive like a combat ship with explosive corners. At home I was yipping it all over and felt like an amature, where at the Nat's, I was "into it" from all the hours of flying every day and didn't give it a second thought and the plane felt rock solid. (Note: I left the plane alone, and learned to fly it that way. It only took a few flights to get back into it. And why put it back, and go through it all over again at the next Nats?)

Sometimes a little "top secret" confidence booster helps. Like some silly little modification you make and don't tell anyone about... "the airfoil varies somwhat from the plans, it's .00000000002% thicker at secret spot on the back side of the highpoint, bwaahahahahaha! I will dominate!!!!" or some such crazy thing. In reality, whatever effect such things have are probably lost in the noise, and certainly inside the building tolerance and capability of the average builder, but hey, if it give's you the confidence to walk out to pick up your handle with a little swagger and burn one in, I say why not. Heh heh.

So... while I know a "great" plane may be required to win a contest, I don't necessarily think you need the "best stunt ship" just one that YOU THINK is the best at that moment and have the confidence to drill through the tricks without choking.

Well, that's my silly .02 cents worth anyways.
EricV

[john e. holliday]

If someone had really came up with the perfect stunt for everybody, why would that person come out with another design of the plane with minor changes.   I think and  still beleive the George Aldrich "Nobler" came the closest.  Look at how many planes have used the Nobler flying surfaces and moment arms.   I have had several that flew really well for me.   But, then I have had some that wound up being fun flying planes as they  will never fly well enough to really be competitive in  the stunt wars.   But, they were different and were built to prive some people wrong when I was told they would not do a stunt pattern.   Dick Sarpolous'   "Wild Goose" is one.   When I manage to get engine set right and weather helps, it will fly a recognizable stunt pattern.   If I really wanted to, I think it could use some changes to make it competitive, but, why as the judges would think it such a strange looking plane they would not give it the score it deserves.  My opinion as I have already had a judge tell me a certain plane I flew did not look right in the air doing the pattern.  In front of other judges it always score well.  But, that was his opinion and I thanked him for the comment.

[Larry Fernandez]

[quote author=john e. holliday link=  My opinion as I have already had a judge tell me a certain plane I flew did not look right in the air doing the pattern.  In front of other judges it always score well. 
[/quote]

This individual should not be judging stunt.
Five foot bottoms are five foot bottoms, 45 degree tops are 45 degrees, intersections are merely tanget points. If you nail all of these and your loops are round and your squares are square, you should score well, no matter what the plane looks like in the air.
He needs to attend a couple of judging clinics if he wants to judge fairly.

Larry, Buttafucco Stunt Team

[Brett Buck]

[quote author=john e. holliday link=  My opinion as I have already had a judge tell me a certain plane I flew did not look right in the air doing the pattern.  In front of other judges it always score well.  


This individual should not be judging stunt.
Five foot bottoms are five foot bottoms, 45 degree tops are 45 degrees, intersections are merely tanget points. If you nail all of these and your loops are round and your squares are square, you should score well, no matter what the plane looks like in the air.
He needs to attend a couple of judging clinics if he wants to judge fairly.

Larry, Buttafucco Stunt Team

  The comment above could mean almost anything, from what you presume (that he was dinging him because it didn't look right) to "its' out of trim, looks bad in the air, and those out of trim conditions are causing you to make a lot of mistakes". I have probably said something similar myself, and I don't think I need to go to a judging clinic.

    You should never ever score the flight based on anything aside from the accuracy of the path it travels, but many times it is clear to the judges (who also tend to be more experienced pilots) that there is something wrong with the airplane that is making it more difficult or causing the mistakes, and it's not all that unusual to comment on it, at least at local contests.

    Brett

[Randy Powell]

I always love these "what is the best" conversations.

There is a performance design envelope that you have to stay in if you want a competitive ship. You can move outside of it, but you will be gain one thing and giving up something else. For instance, I built a lot of high aspect ratio designs. You gain a lightning corner and great groove but give up stability, particularly in turbulent conditions. Everything is a trade-off.

[Shultzie]

LOL![/b  
After reading the discussions about best stunt ship....Hummmmmm!
 Wonder why the name and memories of that little BAAAAHUMMMMBUG! of Bob Baron's amazingly little high revin' 4 pitched prop'd .19 powered "combatish' looking stunt model waaaay back at the Olatha Kansas 68 nationals ...as it cut like a knife THROUGH THOSE MIDWEST SUMMA'TIME WINDS  with all the precision of a CLPA BRAIN SURGEON WITH TOTAL PERFECTION!

That little plane.....being flown BY BOB that DAY!!! (AT LEAST TO MY 2 PENNIES WORTH) IN MY FEEEEBLE' MIND....SHOULD HAVE EASILY TAKEN 1ST PLACE.

[Tim Wescott]

Well, what I'm asking is for someone to name one that does. Which design won the nats/worlds shouldn't they be considered the best. You guys pontificate too much. Just name a few planes that have the potential to win the nats next year.

Then you've changed what you were asking.  You asked which design is "best", and the answer (in amongst all the fruitful discussion about what makes "good") is that there is no "best".  That's it.  That's the answer to your original question.

There's a lot of good designs.  There is no best design.  What's best for me isn't what's best for you.  What's best for you isn't what's best for Paul Walker or Igor Burger, and I dare say (get out your stake and kindling) that what's best for Paul Walker or Igor Burger isn't what's best for you or me.  What's best for anyone this year may not be what's best for that same person next year.

As far as designs that won the Nats or Worlds -- well if you must have just one name for "best", then put the names of all the designs that have placed at Nats or Worlds in the last five years into a hat, pick one, and call that "best".  Then stand back and watch something else win the Nats this year.

[Brett Buck]

Well, what I'm asking is for someone to name one that does. Which design won the nats/worlds shouldn't they be considered the best. You guys pontificate too much. Just name a few planes that have the potential to win the nats next year.

    I did. Understand that thread drift is a very positive feature.  

   Go look at the Trivial Pursuit, Impact and SV-11, those will be within a few percent in any measurable parameter of anything likely to win. That covers just about all the Walker Trophy winners in the last 30 or so years.

  There is essentially no serious debate among the contenders about what sort of airplane is most competitive and what the basic outline and dimensions might be. And at the level you are discussing there is no consequential variation, and it's most definitely NOT a matter of opinion or personal preference, as far as the type of parameters you are asking about.

 I would also contend it's not that much different at any level you look at it, but that is a different argument.

  But, again, you have to consider that the details that you are not asking about are critical, more important than slight variations on the dimensions that covers the entire range of competitive models.

   Brett

[Howard Rush]

But, again, you have to consider that the details that you are not asking about are critical...

Amen, and not conveniently summarized.

[Larry Fernandez]

  The comment above could mean almost anything, from what you presume (that he was dinging him because it didn't look right) to "its' out of trim, looks bad in the air, and those out of trim conditions are causing you to make a lot of mistakes".

    Brett

     Brett

I completly agree. If the mistakes are there, they should be scored as such.
If the plane flies an accurate pattern, the pilot should not receive a lower score just because a judge didnt think the plane looked right to him.

Larry, Buttafucco Stunt Team

[Randy Cuberly]

Is this design, Lou Wolgast's 'Pentastar,' a good performing model?

The kit is offered in two sizes.

Charles

Charles,
Since no one answered your question about the Pentastar I will.
Lou Wolgast is a close friend and flying buddy, and I've flown his Pentastar several times.  In a word yes it is a great performing airplane.  As good as anything I've flown and better than most (I've flown a lot of top stunt planes).  The wing in the Pentastar is basically a GeoXL wing designed and used by Bill Werwage in a lot of his winning stunt ships from the USA1 (World Champ)  to the Thunderbolt (Geobolt).   Lou's uses a ST60.
The airplane needs to be built reasonably light (under 60 oz) to perform best.  It's a big wing at about 720 sq in.
I currently fly a GeoXL with a Belko 56 that weighs 54oz and flys very well.  The Pentastar flies very similar (not surprising).
The Pentastar name comes from the Chrysler Logo and Lou is very much a Chrysler man!!!
The Pentastar does have a geodetic wing and builds best in a lost foam jig from Bob Hunt.

I'm not aware of the kit being offered in 2 sizes.  The only one I'm familiar with is the Big one if that's true.

Randy Cuberly

[Dave_Trible]

I do not have coordinates of real tail airfoil, but here is NACA 0007 with 40% flap deflected to 30 degrees.

You can see that flap instantly deflected to 30 degrees before corner will cause separation. Negative angle of attack 5 degrees will push it to its maximum and negative angle 10 degrees or more again looses its effectiveness because low AoA.

So while short tail very close to wing when AoA of tail is only -5 degrees because of circular flow, will make tail more effective and it will want to do tight turns, tighter than the effect before model enters circular path. While too long tails will not be able to keep entered path because of too small deflection. Both can confuse pilot.

Well ... it is simplified, because I do not count AoA of wing, flap effect on air direction and deflection is also not really instant, but the main effect is clear from that description I thing.

BTW some people asked me why I use such small movable elevator. I think picture shows it well :- ))) .. just not to allow slying over critical AoA before corner. 

Igor, thanks for an instructive read.  This caused a couple of lights to go on (in a very dark place) about issues a encountered while developing my new winged warrior over 6-7 airplanes.  I was trying to squeeze into a smaller package with a higher wing loading and finding a few new puzzles.  On one I wanted to lengthen the tail moment a little so I went from 1.97 to 2.08 ratio and found the machine started the turns well but refused to track rounds accurately.  Went back to shortened moment and the tracking returned.  Another issue I found on only one of three matching airplanes (in dimension and weight +- 2 oz.) This one ship at the same CG required more narrow handle spacing and would stall on bottom corners.  My first thought was the WING was stalling so I fixed it by adding a strip on the flap TE to add flap area-and chord.  What I now realize is the stab/elevator was stalling instead.  On this one airplane I used an elevator horn I had instead of making new.  It was just a bit shorter and gave me a little more elevator than flap deflection. I had assumed the turn was occurring faster than the flaps would deploy to full effect.  Adding to flap chord increased wing AoA sooner.  What I didn't get was the inverse-this allowed the turn with less elevator deflection,  thereby not crossing the red line on elevator stall.  Thanks again!

Dave

[Bill Little]

I can't really offer any thoughts other than to reiterate what has been mostly stated.  There is not one single model which is the "best".  There are MANY stunt models that will win the NATS or Worlds, but they must be matched to the pilot.  It is a known fact that many of the top pilots will trim the same model in different ways.  The MAIN trim issues will be the same, but the objective trim can, and often will, be different.  No one pilot is exactly like another.

ANY of the top level models will do a great job.  Finding the one right for you might be a simple matter of trim.  In the old days, trimming was no where near the level it is today so many built different models before they settled on one.  And has been stated, two "identical" models, built at the same time and everything measurable seems to be the same, they will fly slightly different.......

The pilot and his abilities, the position of the moon, Jupiter aligns with Mars, solar flares, or whatever, are the deciding factors in who "wins".

BIG Bear
RNMM/AMM

[Trostle]

Funny how a few flying sessions later, the posts start to roll in, asking trim questions about planes that "flew perfect, right of the bench".

EricV

Eric,

I have a theory.  Just like energy where the universe has a finite amount of it (at least some think so), there is a fixed number of stunt ships that "flew perfect, right off of the bench".  And that fixed number of those kind of stunt ships were used up around 1951.

And back to the subject of this thread, the "Best Stunt Ship" has not yet been invented.

Kieth

[Randy Cuberly]

Eric,

I have a theory.  Just like energy where the universe has a finite amount of it (at least some think so), there is a fixed number of stunt ships that "flew perfect, right off of the bench".  And that fixed number of those kind of stunt ships were used up around 1951.

And back to the subject of this thread, the "Best Stunt Ship" has not yet been invented.

Kieth

And doubtfully ever will be...However one could simply consider that it's whatever's at the top of the heap at the moment...'course that keeps changing doesn't it...

Randy Cuberly

[Valentin Apostolov]

This is what I want to share with you about the Best....
All our airplanes look alike as we humans are. Each of us is differentl. If you see a good flying airplane
by someone does not meen you can fly his as he does. Try it. Some time ago I tried a first placed airplane and he flew mine. Both of us were dissatysfied. So find yours 'cause we do not alike as humans. Even blood pressure and beat of heart.

Thanks

Valentin Apostolov

[John Desrosiers]

My 03 ford lightning pick up truck . Hell yea.

[John Miller]

Is this design, Lou Wolgast's 'Pentastar,' a good performing model?

The kit is offered in two sizes.

Charles

Charles, Lou Wolgast is a very good, experenced builder, and pilot. I've had the pleasure of watching him fly his Pentastar in the past. It's a great design, that will not hold you back, so don't be afraid of building one for yourself.

I believe you live in California, so check out the Southwest Regionals contest, where you can meet Lou, and watch him fly the Pentastar in competition. The contest is held in Tucson, at the same site VSC is held atin January. It makes a nice break from winter, and there's a lt of great guys to fly with during the contest.

I'm sure some one local there will post the dates and time. I know I plan to be there spectating at the least. I'llm fly if mI can. Might see you there.

Oh, one more thing, Lou's on of the nicest guys you'll ever meet.

[Ted Fancher]

Guys, you must remember that tail volume coefficient is good parameter of flat flying airplanes, but it is not enough for stunt airplanes. The reason is, that while normal airplanes has angle of attack on tail very close to constant (the same like wing), stunt airplanes fly radiuses, so angle of attack on tail is variable and can be +/- 20 degrees on our models. This makes difference between small tail on large arm and large tail on small arm. The difference is in effectiveness of airfoil of deflected elevator.

While short tail solution tends to have stronger and stronger pitching effect during tighter and tighter turn, long tail solution loses its effectiveness as model enters tight turn. So while short models can do tight but not so well controllable turns (so they need to be little nose heavy) long tails will show good initial movement but in reality they do not do 90deg turn so well and they need little more back CG.

So it is necessary first to find proper tail length which can keep initial moment to corner and effectiveness during turn in good balance (so the pilot can do clean and tight corner) and only then to play with area of the tail.

And second thing - larger tail volume can allow back CG, but too large tail and too back CG is also not good, especially if CG goes close or back of 25% of MAC. It is because too back CG can pust tail to produce positive lift, while maneuvering needs negative lift. Theoretically in clean air and perfect airfoils does not matter, but that transition from positive to negative lift in tiny inputs from pilot in level flight cannot do anything positive, I think it simply must lead to hunting, because quaily of flow is quicly changing in such conditions and so also microscopis change of deflection leads to large effect on such large area. My last model has tail area far over 25% of wing area (close to 30%) and CG is still front of 20%. However that large tail allows anything from 15 till 25% without too much difference :- ))

Igor,

Good to see somebody else discuss the potentially counterproductive nature of a CG aft of 25% of the MAC.  That's why all my blather for the last couple of decades continuously cited 25% MAC (and a tail volume appropriate to accommodate it) as a (if not "the") desirable goal in terms of these factors.  Your example of the acceptable CG range on your 30% tail tells the story.  If you had the "classic" era 15 or 16% tail the "trailing edge" of an acceptable CG would be about where yours starts...15% MAC.

Your tail length comments are well taken although, in most cases, of theoretical interest in that tails much longer than "today's usual range" become a problem to build without CGs in the too far aft range.  An understanding of the effects of too long a tail is, of course, valuable in terms of understanding how these things work.  

I love to ponder the value of off the wall "design" innovations by mentally taking them to an extreme as doing so almost immediately makes one aware that there is a limit to almost any perceived advantage when deviating from the "norm".  Think of a stunt ship with a tail moment (in the classic flawed sense) of 48 inches hinge line to hinge line on an  Impact and the impracticality of doing so becomes obvious.  You immediately recognize there is a practical limit even if you're not "schooled" in the science.

Same way with the "everyone knows you can't get too much power" in a stunt ship.  Think of mounting a Pratt and Whitney R2800 on the front of that Impact!   Ooooops!  Or just add nose weight to stabilize your stunter.  Think of putting a pound of lead right behind the spinner of your Impact and you'll quickly realize that isn't really the solution you're looking for.

etc.....

Good stuff, Igor.

Ted

[Howard Rush]

Think of putting a pound of lead right behind the spinner of your Impact and you'll quickly realize that isn't really the solution you're looking for.

Have you looked behind the spinner of my Impact lately?

[Ted Fancher]

Have you looked behind the spinner of my Impact lately?

Howie,

If we're speaking about the electro-magnetically impulsed Impact variety that would be a no.  I thought that was what the battery was for...i.e. locating the CG correctly.  Fill it up to move the CG forward and empty it to move it back.   No?

Ted

p.s.  O.K., then.  Make it three pounds.

[Ted Fancher]

This is what I want to share with you about the Best....
All our airplanes look alike as we humans are. Each of us is differentl. If you see a good flying airplane
by someone does not meen you can fly his as he does. Try it. Some time ago I tried a first placed airplane and he flew mine. Both of us were dissatysfied. So find yours 'cause we do not alike as humans. Even blood pressure and beat of heart.

Thanks

Valentin Apostolov

That's a good point, Valentin.  I wonder, however, if the major difference when you swap flights on top level airplanes with another top level pilot isn't more the difference in handle settings used by each pilot to suit his personal preferences in response and/or neutral angle.  In one series of columns from years ago I talked at length about the desirability of trimming the airplane to its maximum potential and then using our marvelous adjustable handles (and line length, etc.) to adapt our human difference/preferences to the properly trimmed airplane.  I called the two halves of the equation the "Happy Airplane" and the "Happy Pilot".

For instance, a perfectly stable airplane that flies blinding corners and tracks great in rounds but is too sensitive for the human to whom it is attached shouldn't be de-trimmed to lessen its capabilities, instead the handle should be adjusted so the pilot can take advantage of the performance available from the well trimmed airplane using control inputs with which he/she is comfortable.  The plane stays "happy" and the handle adjustment makes the pilot "happy".  Serendipity at its best!

Ted Fancher

[Doug Moon]

Biggest engine they put in was 396...

R

True, but my 68 L35 Camaro was missing the original 396.  The Muncie M21 4 speed was still there so I located a near by passenger 72 454 standard bore for $500 complete!!!!  Tweaked it a little, added some closed chamber small valve 396 heads and a solid lifter camshaft.  It was a torque beast!  I saw my very car for sale not to long ago on Craig's list.  The same guy I traded it too for his 69 vette in 1995 still has it.  If I had the cash I would buy it right back without hesitation. 

[MarcusCordeiro]

True, but my 68 L35 Camaro was missing the original 396.  The Muncie M21 4 speed was still there so I located a near by passenger 72 454 standard bore for $500 complete!!!!  Tweaked it a little, added some closed chamber small valve 396 heads and a solid lifter camshaft.  It was a torque beast!  I saw my very car for sale not to long ago on Craig's list.  The same guy I traded it too for his 69 vette in 1995 still has it.  If I had the cash I would buy it right back without hesitation. 

That sure sounds like a nice ride, and the 4 speed muncie!!
Add a laughing-gas plate and run 10s...
$500 on a 454?!?
Why does that never happen to me??

Marcus

[Dennis Moritz]

Dan Banjok's Vista has a thicker blunter wing than the custom. Nearly a straight leading edge. He flew it to seventh at the NATs. A few extra appearance points would have put it very near to top 5. A plane way outside the conventional specs. I forget the name of the Big Jim Greenaway design (Patternmaster) and it's derivatives. Definitely not an Impact. Windy used those numbers to finish in top 5. Al Rabe's planes differ hugely from the norm. (Any of the current norms.) Heavier with a smaller wing and big flaps. The Sharks certainly do not look like a Bob Hunt or Paul Walker or a Ted Fancher or Randy Smith (and so forth) plane. I bet their numbers have evolved a separate tree. Can we remember way back (a few years) to Berringer.

[Dennis Moritz]

Top 5 this years showed off different flying styles as well.

[Brett Buck]

Dan Banjok's Vista has a thicker blunter wing than the custom. Nearly a straight leading edge. He flew it to seventh at the NATs. A few extra appearance points would have put it very near to top 5. A plane way outside the conventional specs. I forget the name of the Big Jim Greenaway design (Patternmaster) and it's derivatives. Definitely not an Impact. Windy used those numbers to finish in top 5. Al Rabe's planes differ hugely from the norm. (Any of the current norms.) Heavier with a smaller wing and big flaps. The Sharks certainly do not look like a Bob Hunt or Paul Walker or a Ted Fancher or Randy Smith (and so forth) plane. I bet their numbers have evolved a separate tree. Can we remember way back (a few years) to Berringer.

   These are all *very close* in their basic dimensions. I got the impression that the question was about the gross characteristics like aspect ratio, tail moments, etc, in which case they are essentially the same. All within a few percent. The only notable deviation was the B-17.

    If we want to start a different "which design is best" discussion (which will immediately turn into a pissing contest) then that's a bit of a different story. We can already find any number of those threads. I think the correct answer is pretty clear from the results, but that certainly won't stop anybody from arguing about it.

     Brett

[Bill Little]

   These are all *very close* in their basic dimensions. I got the impression that the question was about the gross characteristics like aspect ratio, tail moments, etc, in which case they are essentially the same. All within a few percent. The only notable deviation was the B-17.

    If we want to start a different "which design is best" discussion (which will immediately turn into a pissing contest) then that's a bit of a different story. We can already find any number of those threads. I think the correct answer is pretty clear from the results, but that certainly won't stop anybody from arguing about it.

     Brett

Hi Brett,

I think the two of us agree that you are telling a great truth.  The problem with a discussion like that is that the ones winning Nats and World Championships would not jump in and say THEIR model is the greatest stunt ship around.  If it were so, Ted, Paul, Billy, you, etc., would not go on developing their "designs" trying to find something that suits them better!

Years ago I thought the Nobler was the greatest, then I flew a Thunderbird II, and I liked it a "little" better, then a nice well powered light Ares, etc., etc..  I ave been flying my Geo Juno for almost 16 years in PAMPA class. (ya think I need a replacement? LOL!!)  I have had several Classic ships in that period, all flew well.  But if I fly the Geo Juno well, it is trimmed out, and I am comfortable with it why am I building three new PAMPA class stunters?  One will be very similar to the G.J., the other two wander a bit off that design.  I am looking to see just what does work for me.  You guys don't have to worry about me knocking y'all out of the top five (I might not even be physically able to return), but I will be doing it to have as much fun as I can and do the best "I" can.

Bill