Author Topic: Unequal wings and unequal horizontal stabilizer panels (Read 9038 times)

Matt Piatkowski · « **on:** December 10, 2020, 06:17:41 AM »

Hello,
1. Many stunt models have unequal wings with the same size flaps.
Usually, a small tab is added to the TE of the outside flap in these models (for example Max Bee II by Igor Burger)

2. There are some models with unequal wings and unequal flaps - the outside is longer and has a larger surface area (for example Thundergazer)
There are no tabs on the outside flaps in these cases.

3. There is at least one model with unequal wings, the same size flaps, and unequal horizontal stabilizer panels - the outside panel is 3/4" longer than the inside and has a slightly larger surface area.
The outside panel of the elevator is also 3/4" longer and has a slightly larger surface area than the inside.

What can be a justification for such an unusual horizontal empennage proportion in 3.?
Regards,
Matt

Randy Powell · « **Reply #1 on:** December 10, 2020, 08:49:55 AM »

The outboard wing and the inboard wing panel travel at different speeds. Most of that kind of thing is designed to compensate or allow the plane to carry more tip weight. There are all kinds of issues when you fly in a hemisphere.

Brett Buck · « **Reply #2 on:** December 10, 2020, 08:57:03 AM »

Quote from: Matt Piatkowski on December 10, 2020, 06:17:41 AM

Hello,
1. Many stunt models have unequal wings with the same size flaps.
Usually, a small tab is added to the TE of the outside flap in these models (for example Max Bee II by Igor Burger)

2. There are some models with unequal wings and unequal flaps - the outside is longer and has a larger surface area (for example Thundergazer)
There are no tabs on the outside flaps in these cases.

Those are two variants on the same thing. A very long time ago, since we always required a tab, we started just making the outboard flap larger to start with.

Quote

3. There is at least one model with unequal wings, the same size flaps, and unequal horizontal stabilizer panels - the outside panel is 3/4" longer than the inside and has a slightly larger surface area.
The outside panel of the elevator is also 3/4" longer and has a slightly larger surface area than the inside.

That one, I have never seen or heard of. This is on a competent modern airplane, or a classic from the days of wild cut-and-try?

I think it should be the other way around, with the stab/elevator about 3/8" longer on the inboard side. That would tend to remove the need for the tab on the flap. When I tested it, it made me want to add tab to the *inboard* flap to make up for the larger outboard flap I built in.

Having more area on the outboard stabilizer/elevator would tend to cause outboard roll, just like Bob Palmer's differential flap movement.

Brett

Matt Piatkowski · « **Reply #3 on:** December 10, 2020, 10:25:49 AM »

Hi Brett,
I do not have permission to show you the plan for this plane, but it is a high-level competition stunt machine.
When I have permission, I will share this plan with you.

I agree with you that it should be the other way around, having in mind the flight dynamics.

I cannot exclude human error when somebody prepared the plan, and I am currently inquiring about it.
Stay Safe in these chaotic and dangerous times.
Regards,
M

Ken Culbertson · « **Reply #4 on:** December 10, 2020, 01:25:45 PM »

Quote from: Randy Powell on December 10, 2020, 08:49:55 AM

There are all kinds of issues when you fly in a hemisphere.

An understatement! And when we think we have it all figured out, the wind shifts.

To Brett's comment - "Having more area on the outboard stabilizer/elevator would tend to cause outboard roll,". Is it possible that it would not be a sufficient enough roll to be visible to the judges but would produce a small increase in line tension? I personally like a plane to pull a little bit more in a maneuver.

Ken

Brett Buck · « **Reply #5 on:** December 10, 2020, 01:46:19 PM »

Quote from: Ken Culbertson on December 10, 2020, 01:25:45 PM

An understatement! And when we think we have it all figured out, the wind shifts.

To Brett's comment - "Having more area on the outboard stabilizer/elevator would tend to cause outboard roll,". Is it possible that it would not be a sufficient enough roll to be visible to the judges but would produce a small increase in line tension? I personally like a plane to pull a little bit more in a maneuver.

Probably, but it also causes the line tension to vary all over the place, which will make the piloting more difficult. It's absolutely no different from the Bob Palmer differential flap movement, or excess tipweight, which does the same thing. Essentially anything that "manufactures" line tension is going to cause similar effects.

Brett

Brett Buck · « **Reply #6 on:** December 10, 2020, 01:51:16 PM »

Quote from: Matt Piatkowski on December 10, 2020, 10:25:49 AM

Hi Brett,
I do not have permission to show you the plan for this plane, but it is a high-level competition stunt machine.
When I have permission, I will share this plan with you.

If they are trying to fly with lots of static yaw angle, maybe it makes "sense", because you have already shifted the stab/elevator way to the left, maybe more than is necessary to correct for the velocity gradient.

One of the issues you have to address if you attempt to fly with a large static yaw angle is how you are going to get it to rotate around the axis from you to the CG instead of trying to rotate around the airplane's pitch axis. In my experience, nearly no one can manage it. If they do, it's not for long, and when the magic balance of forces and torques goes away the performance goes straight into the swirling porcelain bowl.

It's also why, say, a Nobler straight out of the kit, is almost impossible to trim for good cornering (either cut off lots of flap or change to 2:3 or even 1:2), even if you can get it to - so much yaw angle that it just wallows around. Part of the need to fly "smooth" is never putting in enough control, abruptly enough, to get it upset in roll/yaw.

Brett

Ken Culbertson · « **Reply #7 on:** December 10, 2020, 02:50:03 PM »

Quote from: Brett Buck on December 10, 2020, 01:46:19 PM

..it also causes the line tension to vary all over the place, which will make the piloting more difficult.

Unless it is predictable as to where and how strong the tension will increase. When I was in my Stunt youth, overhead tension was the Holly Grail. We did ridiculous things to achieve it. I had a Dolphin with a huge wing fence on the outboard wing angled out. We tried everything, except of course adjustable leadouts. (I never said we were smart). I am not advocating this method and I agree that the results will be unpredictable but it might be the "why". Personally I prefer rudder to achieve a very slight yaw instead of roll which is easily achieved through either a Rabe or Trostle rudder.

Ken

Chuck_Smith · « **Reply #8 on:** December 10, 2020, 03:03:07 PM »

Others may think otherwise, but back in the early days we had marginally powered ships and tried all kinds of asymmetry to keep the lines tight.

These days, not so much. Most 60 oz, stunt ships with modern power worry more about precession from the bigger props in my humble experlence. If you want to control yaw - use a rudder.

Another often forgotten little tidbit of physics is that when you make a sharp corner not only the plane's momentum changes, but the lines too.

Chuck

GallopingGhostler · « **Reply #9 on:** December 10, 2020, 05:43:23 PM »

I think you may be right, Chuck.

I noticed some of Hal DeBolt's designs like the All American series have wing asymmetry, inner panel is about 1 rib bay longer than outer. I gather that the outer wingtip velocity is higher than the inner wingtip velocity due to the circle, so for lift outer panel can do the same with less wing area. At the time Hal claimed this helped to maintain line tension (along with flying clockwise instead of the now traditional counterclockwise).

However, if it truly worked, wouldn't more aircraft employ that today? Haven't seen that in any of the kits I have built.

Brett Buck · « **Reply #10 on:** December 10, 2020, 07:26:10 PM »

Quote from: Ken Culbertson on December 10, 2020, 02:50:03 PM

Unless it is predictable as to where and how strong the tension will increase. When I was in my Stunt youth, overhead tension was the Holly Grail. We did ridiculous things to achieve it. I had a Dolphin with a huge wing fence on the outboard wing angled out. We tried everything, except of course adjustable leadouts. (I never said we were smart). I am not advocating this method and I agree that the results will be unpredictable but it might be the "why". Personally I prefer rudder to achieve a very slight yaw instead of roll which is easily achieved through either a Rabe or Trostle rudder.

And you had to fly 3000 flights a year "to get used to it".

Of course, line tension was the reason. Make no mistake, these guys optimized around what they had, just like we do. In this case, limited power.

However, Matt was referring to a "high level competition" airplane, and we no longer have the same limitations. I think those compromises cannot be made and expect to have success. What was state of the art in 1957, or 1967, or 1977, or 1987 *isn't good enough*.

Brett

p.s. I also recognize that the same thing may apply to 1997, 2007, or 2017, depending on who you talk to...

Brett Buck · « **Reply #11 on:** December 10, 2020, 07:29:57 PM »

Quote from: GallopingGhostler on December 10, 2020, 05:43:23 PM

I think you may be right, Chuck.

I noticed some of Hal DeBolt's designs like the All American series have wing asymmetry, inner panel is about 1 rib bay longer than outer. I gather that the outer wingtip velocity is higher than the inner wingtip velocity due to the circle, so for lift outer panel can do the same with less wing area. At the time Hal claimed this helped to maintain line tension (along with flying clockwise instead of the now traditional counterclockwise).

However, if it truly worked, wouldn't more aircraft employ that today? Haven't seen that in any of the kits I have built.

It was not a secret, they shifted the fuselage over to act like tip weight. Unfortunately he also shifted the stabilizer over, too, causing the wild roll motion, and the engine thrust line, which causes it to yaw around, particularly on takeoff.

Brett

Howard Rush · « **Reply #12 on:** December 10, 2020, 08:04:03 PM »

Quote from: Chuck_Smith on December 10, 2020, 03:03:07 PM

Another often forgotten little tidbit of physics is that when you make a sharp corner not only the plane's momentum changes, but the lines too.

I was hoping to keep forgetting it. What’s the first-mode natural frequency of lines on a stunt plane?

Ken Culbertson · « **Reply #13 on:** December 10, 2020, 08:09:30 PM »

Quote from: Howard Rush on December 10, 2020, 08:04:03 PM

I was hoping to keep forgetting it. What’s the first-mode natural frequency of lines on a stunt plane?

Just another of the 400 things that interact to make our planes do what we don't want them to do when we least need it.

Ken

Brett Buck · « **Reply #14 on:** December 10, 2020, 09:40:02 PM »

Quote from: Howard Rush on December 10, 2020, 08:04:03 PM

I was hoping to keep forgetting it. What’s the first-mode natural frequency of lines on a stunt plane?

Depends. That's the only good reason I see to run minimum-size lines - the line whip frequency is higher. .015 are much higher than .018 - which is why my .018s are also only 63.5 feet long.

The line whip first mode can easily be as low as 4 Hz even with otherwise competitive systems - which is uncomfortably close to the time it takes to do a corner, or go from one corner to the next. Hinging and other trim issues sometime excite the higher modes, too.

Brett

Brett Buck · « **Reply #15 on:** December 10, 2020, 09:54:52 PM »

Quote from: Chuck_Smith on December 10, 2020, 03:03:07 PM

Another often forgotten little tidbit of physics is that when you make a sharp corner not only the plane's momentum changes, but the lines too.

But, unfortunately, not at the same time. Hence Howard's comment....

BTW, I spent a few hours today discussing flex modes and their effects in a different context. More like what happens if you hit an anvil with a rubber hammer - better hold it off to the side, because otherwise it will be bouncing right back into your forehead.

Brett

Curare · « **Reply #16 on:** December 10, 2020, 10:29:29 PM »

Quote from: Brett Buck on December 10, 2020, 07:29:57 PM

It was not a secret, they shifted the fuselage over to act like tip weight. Unfortunately he also shifted the stabilizer over, too, causing the wild roll motion, and the engine thrust line, which causes it to yaw around, particularly on takeoff.

Brett

So if you centralised the elevator relative to the wing, what would be the effect?

Brett Buck · « **Reply #17 on:** December 10, 2020, 11:34:55 PM »

Quote from: Curare on December 10, 2020, 10:29:29 PM

So if you centralised the elevator relative to the wing, what would be the effect?

If it was infinitely stiff, it would be much less prone to wild "lift vector out" roll in hard maneuvering, because the torque from the elevator is at least part of what is causing that. Give it up, the lift vector from the tail is down, so you are putting a torque down, centered on the fuselage, which, with the 3" of asymmetry, is inboard of the CG, so it rolls out.

The problems with shifting the tail over the same 3" to center the wing on the tail is that it would put lots of torque of the stab/fuselage joint. And, in any case, while I can't prove it immediately (since I don't know how much the fuselage/engine/tank weighs), I think 3" was too far even if it just acted like tip weight.

Note that shifting the stab over *doesn't* fix the problem with the thrust line, so you would want to put in a bunch of engine offset, too, to fix the crazy takeoff problem.

Alternately you could just lop off 2 1/2" off the inboard wing (or shift the wing over 1 1/2") and leave the rest of it alone - which is what Kaz did, and it flew normally. Unfortunately it also makes it (arguably) illegal for OTS.

Brett

Chuck_Smith · « **Reply #18 on:** December 11, 2020, 05:34:07 AM »

Quote from: Howard Rush on December 10, 2020, 08:04:03 PM

I was hoping to keep forgetting it. What’s the first-mode natural frequency of lines on a stunt plane?

Well there's he fun part Howard, It's not a constant! It's different on the crossing of the overhead eight than it is on the horizontal eight.

And the damping depends on the density altitude. And even more fun, what's the real shape of the standing wave since it's imposed onto a catenary curve due to gravity that's constantly shifting the vector direction relative to the plane and a second curve caused by drag forces on the lines that vary over the radius of said lines who's velocity is variant?

Hmmm, that sounds like math fun. I know what I'l be doing for lunch today! Wish I had a grad student to assign it to.

This stuff is why controline flying is so much fun. It's never the same flight twice.

Chuck

Chuck_Smith · « **Reply #19 on:** December 11, 2020, 07:05:39 AM »

Quote from: Brett Buck on December 10, 2020, 07:26:10 PM

And you had to fly 3000 flights a year "to get used to it".

Of course, line tension was the reason. Make no mistake, these guys optimized around what they had, just like we do. In this case, limited power.

However, Matt was referring to a "high level competition" airplane, and we no longer have the same limitations. I think those compromises cannot be made and expect to have success. What was state of the art in 1957, or 1967, or 1977, or 1987 *isn't good enough*.

Brett

p.s. I also recognize that the same thing may apply to 1997, 2007, or 2017, depending on who you talk to...

Brett,

I like this post. It makes me think. Looking at scores over the years it makes me think that it's not only the airplanes that are changing, but the judging. It sort of implies that instead of being judged to a standard that judging has become relative.

I'll certainly agree that judging is subjective and will never be traceable to NIST, but how can the scores not be increasing from top-to-bottom if it's a result of the airplane technology only? If the judging isn't changing, can one then infer based upon this that the flyers in the old days were better since they had good scores with lesser equipment?

Hmmmm.........

In peace,
Chuck

Matt Piatkowski · « **Reply #20 on:** December 11, 2020, 11:39:05 AM »

Hello Everybody,
Hi Chuck,
I was waiting for someone to bring the issue of judging.
Yes. The models, the flying technique, and the judging are and will be changing.

I believe that judging should be "delegated" to cameras and computers. It is presently possible and does not cost too much.

This approach will eliminate the subjectivity of judging that, unfortunately, is plaguing stunt / F2B competitive flying.

Please recall what happened, for example, to Track &Field and alpine skiing. Everything is computerized now.
Besides, most of the stunt/F2B judges are aging, and there is a shortage of experienced judges.

I have received permission to reveal a general shape of the model - it is Andrey Yatsenko's Shark Ellipse 2.

The plan from Yatsenko's web side is attached, but I was explicitly asked not to show dimensions.

M

Brett Buck · « **Reply #21 on:** December 11, 2020, 11:45:17 AM »

Quote from: Chuck_Smith on December 11, 2020, 07:05:39 AM

Brett,

I like this post. It makes me think. Looking at scores over the years it makes me think that it's not only the airplanes that are changing, but the judging. It sort of implies that instead of being judged to a standard that judging has become relative.

That doesn't seem to be all that mysterious. It has not "become" relative, it was *always* relative.

And you are not entirely correct - in some areas where the range of skills in Expert is extremely wide - the top scores from The Usual Suspects are routinely in the upper 500's to low 600, which is what is necessary to reasonably represent the differences from top to bottom. Same thing at the NATs, as soon as they stopped artificially targeting judges that would give the highest scores in the range of 535, the scoring range and the top absolute score went up dramatically.

It's the same issue with a lot of local contests - if you don't, and the judges don't, routinely fly with or judge nationals quality fliers, you lose your perspective. That's why you cannot possibly just go out and practice a lot by yourself and get anywhere. You can get pretty good that way, but if you have no references you will never know what issues remain.

It's Local Hero syndrome - they win all the contests in their area, they get pushed up to expert where they still are the best. Then they go to the NATs, and not only are they not competitive in Open, they aren't all that certain to win Advanced. Same with judging - Local Hero is the best you ever see, so his score goes into the 520s- 530s. Unless a Paul Walker or David Fitzgerald drops in, then, David gets a 626 and local hero might be in the 400s.

That's why I tell people that they can never, ever, get to a reasonably competitive level by themselves. There are a lot of guys who are determined to go it on there own and then drop into the NATs and win it in the first try. The only person in the remotely modern era to do that was 1967 when Bart Klapinski did it. Where did Bart fly? Los Angeles, when that was one of the hottest competition areas. And this is Bart K. who is generally noted to have the most uncanny natural talent, even among the elites*.

So, it was always relative. What better equipment has done is bring more people to a competitive level, because it's so damn reliable and the performance is such that if you do make a mistake, you can just fly out of it, it will just keep going. Try flying competitive sizes with a classic model and yes, every once in a while you can get through an entire flight without screwing it up.

But most of the time, you will make some minor mistake somewhere and that mistake will blow an entire maneuver. If you slighty overcook a single corner in a square 8, your Fox 35 Green Box Nobler will get out of shape, and you can *never* recover, you might complete it, but it doesn't recover until you are back in level flight for two laps. Make a mistake with your Impact/40VF, and it's back flying again before the next corner comes up.

This is getting off-topic, but this is why I get so frustrated with most of the engine discussions - no one appears to even be interested in competitive systems, and will go out of their way to either screw up their own engines to Classic standards, or become hostile when you point out that fact that the event has learned a lot since 1949 - how DARE you say something bad about my engine, it swept the 1955 Nationals!

Brett

*if *Ted Fancher* has to ask "how the heck does he do that?!" then you know you witnessing something extraordinary!

Brett Buck · « **Reply #22 on:** December 11, 2020, 12:01:52 PM »

Quote from: Matt Piatkowski on December 11, 2020, 11:39:05 AM

Please recall what happened, for example, to Track &Field and alpine skiing. Everything is computerized now.

Both of those are universally objective events, in fact you can judge them with a stopwatch. That is a fundamentally different from attempting to judge figure skating (or now breakdancing) with a computer.

I could not disagree more with your premise.

Brett

Ken Culbertson · « **Reply #23 on:** December 11, 2020, 12:55:59 PM »

Quote from: Brett Buck on December 11, 2020, 11:45:17 AM

...if you don't, and the judges don't, routinely fly with or judge nationals quality fliers, you lose your perspective. That's why you cannot possibly just go out and practice a lot by yourself and get anywhere. You can get pretty good that way, but if you have no references you will never know what issues remain.

No comment, that was simply worth repeating.

Ken

Howard Rush · « **Reply #24 on:** December 11, 2020, 02:29:59 PM »

Quote from: Brett Buck on December 10, 2020, 11:34:55 PM

Give it up, the lift vector from the tail is down, so you are putting a torque...so it rolls out.

And the tail lift, hence the torque, are also functions of the fore-aft CG position.

Howard Rush · « **Reply #25 on:** December 11, 2020, 02:38:09 PM »

Quote from: Chuck_Smith on December 11, 2020, 05:34:07 AM

Well there's he fun part Howard, It's not a constant! It's different on the crossing of the overhead eight than it is on the horizontal eight.

And the damping depends on the density altitude. And even more fun, what's the real shape of the standing wave since it's imposed onto a catenary curve due to gravity that's constantly shifting the vector direction relative to the plane and a second curve caused by drag forces on the lines that vary over the radius of said lines who's velocity is variant?

Hmmm, that sounds like math fun. I know what I'l be doing for lunch today! Wish I had a grad student to assign it to.

This stuff is why controline flying is so much fun. It's never the same flight twice.

Chuck

When you figure out the formula, please express it in density, rather than density altitude. You have to dumb it down for me.

Brett Buck · « **Reply #26 on:** December 11, 2020, 05:01:12 PM »

Quote from: Howard Rush on December 11, 2020, 02:29:59 PM

And the tail lift, hence the torque, are also functions of the fore-aft CG position.

Right, I was only considering the lateral offset, not the fore-aft position. The reductio ad absurdum case is what happens when the outboard wing falls off, which is not terribly unusual in combat, or "world's lightest Ringmaster" experiments.

Brett

p.s. Well, right in a certain set of assumptions. I would note that if the airplane is neutrally stable, you still have to apply torque to change the pitch rate, I_yyomegadot

Trostle · « **Reply #27 on:** December 11, 2020, 05:50:29 PM »

Quote from: Brett Buck on December 11, 2020, 11:45:17 AM

There are a lot of guys who are determined to go it on there own and then drop into the NATs and win it in the first try. The only person in the remotely modern era to do that was 1967 when Bart Klapinski did it. Where did Bart fly? Los Angeles, when that was one of the hottest competition areas. And this is Bart K. who is generally noted to have the most uncanny natural talent, even among the elites*.

Brett

*if *Ted Fancher* has to ask "how the heck does he do that?!" then you know you witnessing something extraordinary!

Hi Brett,

Bart Klapinski was/is an unusual talent in his ability to fly a stunt ship. Please do not misinterpret what I am writing here as anything less than than. Bart flew to a second place at the Nationals in 1963 flying as a Senior, followed by his Open win in 1967. He lived with Dick Williams who coached Bart over a period of time. Dick was an accomplished competitor and designer. Dick was on the one of the first US Team teams at the World Championships (1960?). Bart is a great talent and he had a great mentor.

Keith

Brett Buck · « **Reply #28 on:** December 11, 2020, 08:25:21 PM »

Quote from: Trostle on December 11, 2020, 05:50:29 PM

Bart flew to a second place at the Nationals in 1963 flying as a Senior, followed by his Open win in 1967.

My mistake, I stand corrected!

So, you have seen all the best over an extended period, have you ever seen anyone who had the same abilities as Bart K, in terms of apparent natural talent? There are a few candidates I have, but to my knowledge, none seem to be in the same category. Ted would be one of those candidates, and while he would never toot his own horn, even he has told me many times that he stands in awe when it comes to Bart.

Brett

Scientifiction . · « **Reply #29 on:** December 11, 2020, 09:03:07 PM »

And a World Champion !

=================

Of course, our planes should have pie segment planforms , Less inbord chord, more outer . Being circular'n'all .

Trostle · « **Reply #30 on:** December 11, 2020, 11:03:37 PM »

Quote from: Brett Buck on December 11, 2020, 08:25:21 PM

So, you have seen all the best over an extended period, have you ever seen anyone who had the same abilities as Bart K, in terms of apparent natural talent? There are a few candidates I have, but to my knowledge, none seem to be in the same category. Ted would be one of those candidates, and while he would never toot his own horn, even he has told me many times that he stands in awe when it comes to Bart.

Brett

Hi Brett,

You are correct that I have witnessed the best "over an extended period". And in regard to the question you asked if I have seen anyone with the same abilities as Bart Klapinski, my response is that no one comes to mind. I can remember watching him at that 67 Nats and being totally impressed. The only thing close to that pattern in that period was watching Dick Mathis two years earlier when he was training the judges for the 64 Air Force World Wide Championships and then see Mathis come in second behind Klapinski at that 67 Nats. This is about Bart, and I will not go into other memorable performances I have witnessed over the years.

Bart could pick up the handle connected to someone's airplane and show what the airplane was really capable of doing like nobody I have ever witnessed. However, I will not discuss in any detail the time he flew an airplane without checking out how well it could do the inverted pull out on the first half of a wing over.

Bart and I flew together for many years while I was in the Los Angeles area, we were in the same club together. I moved to Tucson a year after he moved there. We continued to fly together and were in the same club there.

Keith

Matt Piatkowski · « **Reply #31 on:** December 12, 2020, 05:48:44 AM »

Hello All,
I have just received the correction of Shark Ellipse 2 geometry.
The inside flap is 28 mm. longer than the outside.

I have no idea what was Andrey Jatsenko's justification for such a weird combination of flaps and horizontal empennage geometry.

I will ask him directly but, in most cases, Ukrainians and Russians do not answer the questions about their trade secrets.
In cases they do, the way they communicate is frequently linguistically or semantically garbled.
M

GallopingGhostler · « **Reply #32 on:** December 12, 2020, 09:53:38 AM »

Quote from: Matt Piatkowski on December 12, 2020, 05:48:44 AM

I have just received the correction of Shark Ellipse 2 geometry. The inside flap is 28 mm. longer than the outside. I have no idea what was Andrey Jatsenko's justification for such a weird combination of flaps and horizontal empennage geometry.

According to physics, the inner wing panel is travels a slightly slower velocity than the outer, because distances traveled in the circle are different. He was probably trying to compensate for that.

Matt Piatkowski · « **Reply #33 on:** December 12, 2020, 10:11:47 AM »

Hi GallopingGhostler,
What you wrote is correct but only in the case of level, steady control line flight at the small AOA.
In sharp corners, the gyroscopic moment of the propeller, changes in lines tension, and changes in the model's linear and angular velocities affect the flight dynamics so much that the steady-state conditions no longer apply.
Regards,
M

GallopingGhostler · « **Reply #34 on:** December 12, 2020, 11:05:43 AM »

Quote from: Matt Piatkowski on December 12, 2020, 10:11:47 AM

Hi GallopingGhostler, What you wrote is correct but only in the case of level, steady control line flight at the small AOA. In sharp corners, the gyroscopic moment of the propeller, changes in lines tension, and changes in the model's linear and angular velocities affect the flight dynamics so much that the steady-state conditions no longer apply.

Oh, I was referring to a reason as to why,

not as to the dynamics of the entire situation.

But then, I worked for Douglas Aircraft in the 1980's in their structural test laboratories, not design.

We'd test specimens to the point of breaking,

for which I am still quite capable of doing in the CL circle.

Brett Buck · « **Reply #35 on:** December 12, 2020, 11:29:26 AM »

Quote from: Matt Piatkowski on December 12, 2020, 05:48:44 AM

I will ask him directly but, in most cases, Ukrainians and Russians do not answer the questions about their trade secrets.
In cases they do, the way they communicate is frequently linguistically or semantically garbled.

"Trade Secrets"?! You've got to be kidding! Amazing.

I suppose they know their customer base....

Brett

Brett Buck · « **Reply #36 on:** December 12, 2020, 11:51:00 AM »

Quote from: GallopingGhostler on December 12, 2020, 11:05:43 AM

Oh, I was referring to a reason as to why, not as to the dynamics of the entire situation. But then, I worked for Douglas Aircraft in the 1980's in their structural test laboratories, not design. We'd test specimens to the point of breaking, for which I am still quite capable of doing in the CL circle.

You were right the first time. Matt is kind of right because a lot of the time, other trim issue overwhelm the effect.

But you definitely do see a difference whether you have asymmetry or not, essentially *only* in maneuvers (steady-state you cannot tell the difference, aside from having to have more or less tip weight) and you have to trim it differently if there is even 1/2" difference. I have varied the asymmetry on a single airplane, and many people have built the same airplane with different degrees of asymmetry. It is a a very predictable effect and mostly manifested itself in maneuvers, not steady state - because of nothing else, having the Cp shifted laterally makes a lot more difference when you have 60 lbs of lift, instead of 4.

But the problem is that even at full 50-60 lbs of lift, even the tiniest bit of other trim errors or misalignment can easily overwhelm the effect. On a typical airplane, figure the inboard wingtip is going about 6 feet/second slower than the outboard. That's not nothing but consider the most common trim problem - lots of rudder offset, with the airplane dragged back to tangent by moving the leadouts forward. That works great at one speed and one value of line tension.

As soon as you start maneuvering, the airplane slows down and the line tension, at least temporarily, goes up. The effect is that the airplane wildly yaws nose-in, the inboard wingtip is driven backward and the outboard forward - maybe more differential in velocity from that effect is more than that from going around in a circle.

That's what Matt appears to mean with regard to dynamic conditions. The effects seen in static flight are still present, but they other effects may be more important.

Brett

Matt Piatkowski · « **Reply #37 on:** December 12, 2020, 12:41:36 PM »

This one is for Brett.

The people manufacturing now the best, in my opinion, RTF F2B planes in the world, namely Solomianikov, Yatsenkos brothers, Leonidov and Astrakharchik, have a particular communication style and mode of operation that is different than widely accepted in the Western world.

The guy I was, quite frequently, flying together during this strange, 2020 Covid-19 season, Gustavo Urtubey from the Balsa Beavers Club, ordered the New Classic from Yatsenkos many years ago and could not get it.

He was getting a bit desperate and consulted me about what to do. I have told him to be patient and explained the differences between Western and Eastern mentality.

I am from Eastern Europe, but I got "Canadized" and "Americanized" sufficiently during the last thirty-five years to see differences in the communication style in the West and the East.

Gustavo received his New Classic a month or so ago, but it arrived without an explanation.

Best Regards,
M

Brett Buck · « **Reply #38 on:** December 12, 2020, 01:37:12 PM »

Quote from: Matt Piatkowski on December 12, 2020, 12:41:36 PM

This one is for Brett.

The people manufacturing now the best, in my opinion, RTF F2B planes in the world, namely Solomianikov, Yatsenkos brothers, Leonidov and Astrakharchik, have a particular communication style and mode of operation that is different than widely accepted in the Western world.

The guy I was, quite frequently, flying together during this strange, 2020 Covid-19 season, Gustavo Urtubey from the Balsa Beavers Club, ordered the New Classic from Yatsenkos many years ago and could not get it.

He was getting a bit desperate and consulted me about what to do. I have told him to be patient and explained the differences between Western and Eastern mentality.

I am from Eastern Europe, but I got "Canadized" and "Americanized" sufficiently during the last thirty-five years to see differences in the communication style in the West and the East.

Gustavo received his New Classic a month or so ago, but it arrived without an explanation.

My comment was not really on their business practices, but that they think they have "important secrets" that are critical to maintain. There are no secrets, people who think there are, are generally fooling themselves.

I will reserve comment for now about the rest of it. I think plenty of people have opinions about their general reputation as suppliers.

Brett

p.s. Keeping secrets not only doesn't work, it is counter-productive. A lot of people here used to try that, and it worked at the time, but not any more. I and many others will tell you exactly what we are doing, why, and why doing something else may or may not work, in as much detail as we know it. When people try to keep secrets, me and several otherws will make it their life's work to explain it to everyone.

This has an interesting side effect - a lot of times, you will tell people exactly what to do and why, and at least some will go off and do the opposite, just to show they know better, out of pure stubborness. Most of the time, it doesn't work, but it's always possible they find something in the process and then the rest of us learn something new.

Matt Piatkowski · « **Reply #39 on:** December 12, 2020, 05:19:26 PM »

Hi Lauri,
I was trying to receive the basic geometry with dimensions of all Ukrainian and Russian models, and I could not get them.
One of the top Polish F2B fliers bought Shark Ellipse 2 this year and, only because I know him, I received the basic dimensions of the plane.

I have learned about unequal horizontal stabilizer panels reviewing these dimensions.

Harmony is desirable, but verifiable technical information means more to me.

Regards,
M

Brett,
Like you wrote, " Keeping secrets not only doesn't work, it is counter-productive..".

Regards,
M

Matt Piatkowski · « **Reply #40 on:** December 13, 2020, 04:53:51 AM »

Hi Lauri,
I am relying on the measurements done by my F2B colleague in Poland.
He measured the dimensions from Shark Ellipse 2 standing in front of him.

I do not think he made an error measuring the horizontal empennage with a metal ruler, but I will ask him to verify the dimensions.
Stay Safe,
M

Matt Piatkowski · « **Reply #41 on:** December 13, 2020, 05:56:29 AM »

Lauri,
I know that Yatsenko Brothers produce many variations of the same model but tracking these variations is very difficult.
Yatsenkos do not bother to update their website, and they do not use the models/parts numbering system to track the variations.

Mace R-2 Shark is geometrically different that Shark Ellipse 2. The basic dimensions of Mace R-2 Shark are available on http://discovery-aeromodels.com/, but Shark Ellipse 2 plan has no basic dimensions.
For Gee Bee R3 there is no plan at all.

Like I wrote before, the Ukrainians and Russians produce the best F2B models, but their communication skills and willingness to share the information are below average.

Matt Piatkowski · « **Reply #42 on:** December 13, 2020, 06:48:57 AM »

Lauri,
I hear what you are saying, but I cannot comment until the final confirmation from my colleague in Poland.
I could not find any logical explanation for the sizes of the outside panels of the stabilizer and the elevator in Shark Ellipse 2.
I have initiated this discussion to hear different opinions, and you have just expressed yours.

Best Regards,
M

Matt Piatkowski · « **Reply #43 on:** December 14, 2020, 05:41:55 AM »

Hello Everybody,
I have just received the confirmation that Shark Ellipse 2 has unequal horizontal stabilizer and elevator panels, having dimensions that I specified in my first message.
Correction: I have stated in my first message that this F2B model has the inside flap the same as the outside flap. The inside flap is 28 mm. ( 1.10 ") longer than the outside flap and has a slightly larger surface area.

Please see the photo of Shark Ellipse 2 and note the shape of the tips of the flaps.
Regards,
M

Lauri Malila · « **Reply #44 on:** December 14, 2020, 12:01:05 PM »

I just talked with Andrei.
The model with Asymmetric tail was made made by a special request of Pawel. Andrei would never make it by himself.
Pretty quickly Pawel found out it was not a good idea, and now Andrei is making him a new model with normal, symmetrical tail. L

Dietmar Morbitzer · « **Reply #45 on:** December 14, 2020, 12:05:04 PM »

Hi Matt,
I wonder what is your intention when asking for all this
things you do. You criticise Ukranien manufacturer for not
telling you each little detail from their newest competition
airplane and not show everything what makes the difference.
I think you forgot thats also a business for some of them.
I'm pretty shure that the next worlchampionships will show
a lot of shark, sorry, sharp looking planes, and they will not
all build by the original manufacturer.
You will not find the holy grail, you only make yourself
more and more dissatisfied when you hunt all the big secrets.
I think you start late with control line stunt as I did,
so I will tell you my secrets:
Built or buy a very competitive airplane which is lightweighted
strait, stiff and has a very consistant running engine no matter
electric or methanol. The engine run must be allways consistant
and reproducible.
Find a flying buddy and practice with him as often you can under all
weather conditions. Criticize yourself to develop your skill, thats it.
Last thing, I will never accept a judging by computer, you only can loose, why?
1. I will not have the time or the area to practice like other, younger people have,
my only chance is my individual style and personality in combination
with correct flying skills as much as possible.
This is no stopwatch class, I come from rc pylonracing and I know what I am
talking about. People tell me when I start stunt competition that I
will come home allways at the last from the board, because I have no name
and a lot of other funny things and I will as a noname never get the point
I deserve, well, the opposite thing happened, I often felt to get to much points,
and allways accept my result in one way and the other.
If you cant life with it, go racing. Thats the reason I go racing when I was younger.
So no need to despair, concentrait on yourself, practice a lot and have fun while you fly.
Dietmar

Matt Piatkowski · « **Reply #46 on:** December 14, 2020, 02:33:47 PM »

Hi Lauri,
I am currently waiting for Pawel's comments.
Happy Holidays / Merry Christmas

Hi Dietmar,
Thank you for your advice and opinions.
Happy Holidays / Merry Christmas

Brett Buck · « **Reply #47 on:** December 15, 2020, 11:56:29 PM »

After having thought about it for a while, what this is likely to do is to roll the airplane outboard during maneuvering, and *maybe* compensate for any differential drag from having a longer inboard flap, presumably because it is longer than it needs to be to compensate for the velocity gradient. Both the stab and the wing will make it want to roll outboard, but the wing will make it yaw nose-in and the tail will make it want to yaw nose-out.

The alternative, much less likely, is that the airplane is designed to fly yawed nose-out and this just centers up the tail with respect the skewed line of flight. That one is a stretch, because you wouldn't want that much differential in the wing.

Brett

phil c · « **Reply #48 on:** February 04, 2021, 09:09:44 AM »

Quote from: Matt Piatkowski on December 14, 2020, 05:41:55 AM

Hello Everybody,
I have just received the confirmation that Shark Ellipse 2 has unequal horizontal stabilizer and elevator panels, having dimensions that I specified in my first message.
Correction: I have stated in my first message that this F2B model has the inside flap the same as the outside flap. The inside flap is 28 mm. ( 1.10 ") longer than the outside flap and has a slightly larger surface area.

Please see the photo of Shark Ellipse 2 and note the shape of the tips of the flaps.
Regards,
M

Hi Matt- the good way to figure out what is going on (which I suspect you've already done) is to draw up the layout and establish exactly the sizes of the various surfaces, where the mean aerodynamic centers are located, tip weight and moment, plus the thrustline location in the planview. If you want to be really picky do the same for the vertical elevation for especially the rudder elevation and the landing gear and pants, if used.

The interesting comparison is between that asymmetrical plane, and the same design with all the parts exactly symmetrical around the fuselage centerline. If you get really in to it, calculate the % differences between the two layouts.

As it always has, the outboard wing tip flying faster than the inboard tip forces us to use tip weight to get the lateral balance just outboard of the MAC. That reduces the tendency of the wing to roll from elevator control, and acceleration also causes the plane to turn a bit out of the circle. Tip weight has the advantage that it only directly influences accelerations in maneuvers or from wind.

Changing the lateral symmetry with wing area placement or inboard/outboard flap size is a bit more complicated. The accelerations from flap angle, area, and angle of attack also interact with the wind direction and vary as the wind direction changes in a maneuver. A steady wind is fairly easy to accommodate. Gusty, changeable winds can have more effect because various parts of the plane may be in different air streams. An overhead eight or the hourglass are probably the most affected. The plane goes from low level, relatively slow wind speed to the maximum directly overhead. The airspeed changes all the way to the top of the circle and so does the likelihood of gust from a different direction.

With electric planes now having directly controllable power maybe its time to go to smaller flaps and take a little hit in the plane not appearing to keep a steady angle of attack. Without the exhaust betting blown around by big flaps the plane will look more steady and controlled in low, tight radius maneuvers. More AOA can substitute for some flap area/movement.

If there are still problems, leadout position also affects roll. The further back it is the more the plane will yaw and roll.(but you know that!)

Phil C

Lauri Malila · « **Reply #49 on:** February 04, 2021, 09:39:43 AM »

Quote from: Lauri Malila on December 14, 2020, 12:01:05 PM

I just talked with Andrei.
The model with Asymmetric tail was made made by a special request of Pawel. Andrei would never make it by himself.
Pretty quickly Pawel found out it was not a good idea, and now Andrei is making him a new model with normal, symmetrical tail. L