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  • December 17, 2017, 10:18:59 PM

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Author Topic: New Stunter - Gymnast indoor flyer  (Read 1161 times)

Online Larry Renger

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New Stunter - Gymnast indoor flyer
« on: December 07, 2017, 08:49:07 AM »
The Knights of the Round Circle will again be training kids at the AMA Expo West.  We needed something to demonstrate that CL models can do more than go around in circles.  #^

The Gymnast is my answer.  It has a 92 sq.in. wing and weighs just under 3 ounces.  Working flaps and a KR timer for maneuvering boost.
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan

BTW, Dracula Sucks!


Offline John Rist

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Re: New Stunter - Gymnast indoor flyer
« Reply #1 on: December 07, 2017, 01:35:08 PM »
Looks good.  Is their plans available?
John Rist
AMA 56277

Online Larry Renger

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Re: New Stunter - Gymnast indoor flyer
« Reply #2 on: December 07, 2017, 02:02:40 PM »
It hasn't flown yet, I will start testing at the indoor flying session Monday.  Once the design is tuned in, I will be glad to publish the design.
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan

BTW, Dracula Sucks!

Offline mike londke

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Re: New Stunter - Gymnast indoor flyer
« Reply #3 on: December 07, 2017, 03:57:50 PM »
Very cool!
AMA 48913  USPA D-19580  NRA Life Member  "Don't let the planet sneak up on you"

Offline Igor Burger

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Re: New Stunter - Gymnast indoor flyer
« Reply #4 on: December 08, 2017, 06:42:00 AM »
Larry we found that flaps 1/ do not work well on slow and flat indoor wings and 2/ are not necessary thanks to low wing load.

Online Larry Renger

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Re: New Stunter - Gymnast indoor flyer
« Reply #5 on: December 08, 2017, 04:16:19 PM »
Interesting comment! Any idea why flaps donít add performance? I would at least think they would smooth out the control response. Also, even if the flow over the top of the flap is fully separated, it seems the pressure buildup on the bottom would have some effect.

One thing I failed to mention is that we are limited to 15ft (5 meter) lines where we will be flying. This puts some real constraints on the size and power of the model design. I can handle lap times in the low 4second range, but not much lower. (Being not as young as I used to was!)
« Last Edit: December 08, 2017, 04:33:13 PM by Larry Renger »
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan

BTW, Dracula Sucks!

Offline Igor Burger

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Re: New Stunter - Gymnast indoor flyer
« Reply #6 on: December 08, 2017, 04:45:35 PM »
4 reasons:

1/ Flap on thin airfoil makes higher lift, but in negative AoA so it will work standard way (flaps to elevator 1:1) only in case that elevator is very small (so that it has so low authority that negative pitching moment will overdo elevatotor lift and so model will fly at negative AoA) ... such model cannot be stable as we expect on out c/l models (because of low stab authority). In normal standard configutation of large tail making high static stability when model gets positive AoA in maneuver- say 5 degrees optimal for flat airfoil, where lift coefficient goes to 0.3, the same wing flapped with say 10 or 15% flap will fall down stalled at lift coefficient aproximately 0.1 - those numbers look very low, but remember it flies at sub critical RE numbers somewhere at 50 000. It works more like insect wings, than normal. And you can see that all insects have flat straight wings :- ))

2/ Outdoor models need flaps because they are too heavy for small wings, reason is, we need small wings for turbulent air to resist in wind, but able to make tight corners - that is not necessary indoor, you can use large wing without problems, so flaps are not necessay.

3/ Indoor has micro line tension (centrifugal force overhead is even smaller than gravity), flaps have large hinge moment (aproximately 5 to 10 times more than elevator) slow flight simply does not keep tight lines for flaps.

4/ Amount of tip whirpools depends on aspect ratio and lift coefficient. We fly in calm wind without wind which can blow them out, so making small wing with flaps making the same lift at higher lift coefficiet as large wing at lower lift coefficient makes thing worse. No problem outside in little wind, but nightmare in calm air indoor.   

Offline Igor Burger

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Re: New Stunter - Gymnast indoor flyer
« Reply #7 on: December 08, 2017, 04:47:29 PM »
One thing I failed to mention is that we are limited to 15ft (5 meter) lines where we will be flying. This puts some real constraints on the size and power of the model design. I can handle lap times in the low 4second range, but not much lower. (Being not as young as I used to was!)

I fly at 5.5 lap time, means slower than outside and yes, also on 5m lines.

Online Larry Renger

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Re: New Stunter - Gymnast indoor flyer
« Reply #8 on: December 09, 2017, 10:17:41 AM »
Thanks for the explanation. I will try it as is, but am ready to go with fixed flaps as you recommend.  H^^
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan

BTW, Dracula Sucks!

Online Larry Renger

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Re: New Stunter - Gymnast indoor flyer
« Reply #9 on: December 11, 2017, 06:48:44 PM »
It flies just fine with the working flaps. It needed tip weight and a bit more prop pitch, but there is a lot of potential here for a stunt demo model. No, it wonít beat a state of the art model flown by a champion, but for wowing the unwashed masses, it should be just the thing.

Precision slow flight is necessary for competition, but speed and snappy maneuvers make for good demos.  ;D
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan

BTW, Dracula Sucks!

Offline Igor Burger

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Re: New Stunter - Gymnast indoor flyer
« Reply #10 on: December 12, 2017, 12:35:12 AM »
It is sometimes too quick also for experienced flyers doing gemo flights :- ))))))))))))))))



Offline Skip Chernoff

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Re: New Stunter - Gymnast indoor flyer
« Reply #11 on: December 12, 2017, 03:59:09 AM »
That was crazy!

Offline Will Hinton

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Re: New Stunter - Gymnast indoor flyer
« Reply #12 on: December 12, 2017, 07:15:45 AM »
The one dude in the red shirt is a pretty good athelete!  Jumped another flyer and lines, caught up (for a little bit) with the others, really fun to watch.
John 5:24   www.fcmodelers.com

Offline Igor Burger

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Re: New Stunter - Gymnast indoor flyer
« Reply #13 on: December 12, 2017, 07:36:06 AM »
this was little better :- ))



Online Al Ferraro

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Re: New Stunter - Gymnast indoor flyer
« Reply #14 on: December 12, 2017, 07:39:13 AM »
The one dude in the red shirt is a pretty good athelete!  Jumped another flyer and lines, caught up (for a little bit) with the others, really fun to watch.
  I hope he doesn't show up to fly at our racing contests in Middlesex NJ!!!  **)
Al

Offline john e. holliday

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Re: New Stunter - Gymnast indoor flyer
« Reply #15 on: December 12, 2017, 11:27:39 AM »
If only these could be produced low enough in cost to lure the youngsters and newbys.
I was always taught to respect my elders, but it keeps getting harder to find one.
Today I broke my personal record for most consecutive days lived.
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Online Larry Renger

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Re: New Stunter - Gymnast indoor flyer
« Reply #16 on: December 12, 2017, 11:35:18 AM »
The most expensive part is the timer! The rest of the model with battery is probably under $50. Small Suppo motor and 10 amp ESC, 350 2s battery, all from Hong Kong.  A less sophisticated, cheaper timer might be available somewhere, I just have several KR timers so that is what I used. less than one sheet of foam and scraps of 1/64 and 1/32ply. 1/2A bellcrank.  y1
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan

BTW, Dracula Sucks!

Online bob whitney

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Re: New Stunter - Gymnast indoor flyer
« Reply #17 on: December 12, 2017, 11:47:54 AM »
I thought he was from N,J  y1
rad racer

Online Al Ferraro

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Re: New Stunter - Gymnast indoor flyer
« Reply #18 on: December 14, 2017, 10:16:23 AM »
I thought he was from N,J  y1
Running around the outside of the circle, hooking everyone's lines while their pitting. Na that never happens in NJ. <=
Al

Offline Igor Burger

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Re: New Stunter - Gymnast indoor flyer
« Reply #19 on: December 14, 2017, 10:38:49 AM »
Running around the outside of the circle, hooking everyone's lines while their pitting. Na that never happens in NJ. <=
Al

Sounds like you need more new beginners :- ))

Online Larry Renger

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Re: New Stunter - Gymnast indoor flyer
« Reply #20 on: December 14, 2017, 05:34:57 PM »
Flew the model again today. With a 4.3Ē pitch prop, it is way fast. The space to fly was really tight, so only enough maneuvers were done to check out the trim. Oddly, the tail surfaces were twisting in flight. I could not see it but outside observers did.

Without the ability to keep maneuvering, 2 minutes is a LOOOONG time.  :P. A 350 3s battery is good for about 4 minutes of flight time.

A bit tail heavy, but plenty of leeway to move the battery forward. 3 lead bbs seem to be just the right amount of tip weight.

Moved the battery about 1/2Ē forward, and moved the pushrod to the inner hole on the bellcrank. Still lots of control throw. Flaps are about 2/3 the throw of the elevator.

Definitely showing great potential as a show model!  ;D Zippie, zoom, zoom.  VD~

I may or may not have a chance to fly it again before turning it over to the AMA Expo crew. Sadly, I wonít be on hand this year.
« Last Edit: December 14, 2017, 06:55:57 PM by Larry Renger »
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan

BTW, Dracula Sucks!

Online Keith Renecle

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Re: New Stunter - Gymnast indoor flyer
« Reply #21 on: December 14, 2017, 09:30:30 PM »
Sounds like you need more new beginners :- ))
I was waiting for one of the guys to fly inverted.......... #^

Keith R
Keith R

Online Larry Renger

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Re: New Stunter - Gymnast indoor flyer
« Reply #22 on: December 14, 2017, 09:48:49 PM »
In 1974 we took 20 new Cox Me109 models to the nationals to stage a 1/2 A stunt contest. Someone got the bright idea to fly all the models at once. It actually went OK until one guy decided to go inverted and wrapped up all the other lines. It rained plastic and I was not a happy camper. I wanted these experts to take the models home to show off. Instead there was a pile of junk. AAAARGH!
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan

BTW, Dracula Sucks!

Online Larry Renger

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Re: New Stunter - Gymnast indoor flyer
« Reply #23 on: December 15, 2017, 06:51:53 PM »
Well, the Gymnast is in the hands of the EXPO crew and out of mine. It will be interesting to see how they make out with it! I hope it survives. #^

If you can make the show, be sure to look up the Knights of the Round Circle display and Flying demos and training. Say hi to the guys, it really is a LOT of work to do all that for 3 days.  H^^

We are supposed to be in the smaller demo room on the North West side of the center.

Come and try out the ET-1 trainers. They arenít just for kids, and expert flyers have enjoyed them too.

I suspect that extra well qualified competition aerobatics and combat pilots might sneak in a Gymnast flight if you ask real nice! We only have one of them, and itís built to fly, not crash. Has to last the whole show.

Sorry not to be there, but I will be having a great time elsewhere. ;D. First show I have missed in decades!
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan

BTW, Dracula Sucks!

Online Larry Renger

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Re: New Stunter - Gymnast indoor flyer
« Reply #24 on: Yesterday at 06:58:25 PM »
The original model is now in the hands of our Knights of the Round Circle demo and training crew. Be sure to visit with them at the AMA Expo West in Ontario, CA first weekend in January.  H^^

Try out the ET-1 trainer, it is fun for even the most advanced pilot, not mentioning potential retreads. But let the kids have a turn too!  :D
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan

BTW, Dracula Sucks!


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