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Old May 14, 2001, 12:04 AM
joe
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greenbay,wi,usa
Joined Apr 2000
412 Posts
Has anyone else seen a gasser just fly apart

I was at the field flying my ninja
after landing a guy was getting ready to take up a 1/4 scale with a 2.4 fox gass engine
my electric is looking beter and beter as I saw this loud thing rumbling on the ground
I don't have anything against gass because I am about 50 50 slimer and electric but boy did this thing run rough
any who after he took off he flew around for a while getting the thing trimmed out
he was doing a circut when with a loud bang the aileron just flew off
he didn't have nay fluter it just came off
I think even my heart stoped for a second
any who he landed with one aileron safely so I helped him find the other one
when I picked it up you could see the ca hinges sheared in half
when I got back to his airplain I checked it out and the other wing servo was almost riped out
worst of all his rudder servo arm screw was almost all the way out so it could have been wourse
think I will stick with my electric smoothies

Crazy Joe
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Old May 14, 2001, 12:46 AM
Caution:Makes sharp left turns
Troy's Avatar
United States, CA, Lake Forest
Joined Feb 1999
6,009 Posts
Vibration is a nasty little bugger. It can cause havic on your airplane and equipment. I can't tell you how many times I've had to inform people about balancing propellors. Some are like "Huh?? You have to balance them." It's also so important to do preflight checks everyday before you fly and even between flights. I give all surfaces a tug and a wiggle to see if they are tight. It's a habit that has caught mistakes waiting to happen on other people's airplanes I was about to fly. Sounds like his CA hinges might have been soked with CA to the point that they may have become brittle or he could have had a quick burst of flutter.
By the way, flutter on a control surface can shake the rest of the airplane in ways you couldn't imagine. I've seen the results of wing tip (the whole tip) flutter on a big thermal ship after a serious launch up a winch. Shook the plane so bad it cracked the tail boom, stripped servo gears on control surfaces on the other side of the wing, and vibrated the V-tail out of it's molded saddle. Serious stuff Glad to hear your Ninja's runnin smooth

[This message has been edited by Troy (edited 05-14-2001).]
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Old May 14, 2001, 09:15 AM
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Quebec, QC, Canada
Joined Mar 2001
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Quote:
Originally posted by joe:

1) up a 1/4 scale with a 2.4 fox gass engine
my electric is looking beter and beter as I saw this loud thing rumbling on the ground

2) when I picked it up you could see the ca hinges sheared in half when I got back to his
These two things just don't go together. The crash demonstrated it clearly.

Cheers --- Larry
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Old May 14, 2001, 11:32 AM
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Palmdale, CA
Joined Oct 2000
13,371 Posts
I had a Nordic A-2 glider on tow go into flutter at the dihedral break.. both sides. It nosed over and crashed.
Flutter isn't solely a problem with i.c. motored planes.
Many highspeed gliders "blow up" completely in the air when flutter chews on them.
It is generally created by a sloppy control system installation.. too small a pushrod; pushrod connected to the horn using the hole closest to the surface for more motion;a heavy surface; too few hinges; poor hinges;
a long heavy unsupported pushrod... can happen in any style of plane.
.
Sparky Paul http://www.angelfire.com/indie/aerostuff
PJB's Seriously Aeronautical Stuff http://www.networkone.net/~pjburke/index.html
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Old May 14, 2001, 11:55 AM
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Berkeley, CA USA
Joined Apr 2001
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Quote:
Flutter isn't solely a problem with i.c. motored planes.
Many highspeed gliders "blow up" completely in the air when flutter chews on them.
[/B]
Think that's bad, you should see a rocket go into fin flutter under boost.
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Old May 14, 2001, 01:17 PM
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Palm City, FL
Joined Dec 2000
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Even sadder to see a gasser peel his plane across the field, hear the buzz of a surface going into flutter and watch the goof just keep on blowing by the flightline until it shreds apart and craters the field. Then of course he yells "I don't believe it... I musta got hit!!!"

I saw a good one at one of the early Top Guns (before the Polo Club)... guy was flying his jet at a radar gun out on the field diving to get a speed trophy when he popped up over the gun the surfaces or servos gave up and there was this spectacular slow-motion explosion of parts and dust as it rolled across the field. If there had been a little fireball in there it would have been a perfect scale reproduction of a full-sized crash.

Mik, saw a great one at the Heart Of Ohio Jet Fly two years ago when they launched a 5-foot-high R/C Space Shuttle off a 10-foot gantry.... the whole Shuttle experienced a catastrophic failure just off the launch pad that looked just like the Challenger failure. The engine spun around in slow-motion and put a 4-foot crater in the farmer's field behind the flightline.
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Old May 14, 2001, 05:53 PM
Super Senior Member
Albuquerque, NM
Joined Feb 2000
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I saw a few weeks ago, a guy with an over powered FMA Razor (mag mayhem I think) was trying to do high-speed passes. Evidently it was overly stressed and exploded in mid air. Took the guy about 20 minutes to find all the parts.
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Old May 14, 2001, 07:55 PM
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Berkeley, CA USA
Joined Apr 2001
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Quote:
Originally posted by TimOBrien:

Mik, saw a great one at the Heart Of Ohio Jet Fly two years ago when they launched a 5-foot-high R/C Space Shuttle off a 10-foot gantry.... the whole Shuttle experienced a catastrophic failure just off the launch pad that looked just like the Challenger failure. The engine spun around in slow-motion and put a 4-foot crater in the farmer's field behind the flightline.
heh...can't do that with an electric motor . I do have a PML Phobos that i covered with some really old Solar film that managed to peel off, along with the launch lugs at .95 Mach (1105 FPS). You can get almost anything to fly apart if you can get it going fast enough. (ask a rocket guy about 'Max Q shread')

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Old May 14, 2001, 11:03 PM
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Folsom,Ca,USA
Joined Apr 2001
992 Posts
Hi gang,

When you hear flutter, do you know how to tell what is fluttering?

Climb to about 300ft, push over into a full throttle 45 deg dive, last piece to hit to the ground was source of flutter!

Dave
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Old May 15, 2001, 12:13 AM
joe
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greenbay,wi,usa
Joined Apr 2000
412 Posts
the guy it hapened to came in to the hobby shop I work at
I found it interesting the reasion for his his aileron came off
he switched all of his controll horns to the dubro heavy duty ones
this would not have been a proublem but he picked up the futaba one's
he had hitec servos
these have a diferent spline but you can fit a futaba servo arm with little efort
he was a great piolet in his abuility to land almost perfectly with a cap 232 on ruder and elevator alone
his other aileron was rendered usless in the air and was almost compleatly striped out on landing
he ordered some stronger hinges and with luck he will have no more scares
he is a realy nice guy to work with

happy flying
Crazy Joe
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Old May 15, 2001, 08:28 PM
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Los Alamos, NM, USofA
Joined Nov 2000
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Quote:
Originally posted by Larry Marshall:
These two things just don't go together. The crash demonstrated it clearly.
Cheers --- Larry
Hi Larry,
I would have to disagree with you. I had a Midwest Cap232 with CA hinges on all control surfaces. Different brands are of varying quality. I've used the Sig brand exclusively and have had nothing but good results with them. I have seen the "X and Y brands" fail, however.

I took the time to seal the gaps and counter-balance the control surfaces, too. As the models get bigger, you have to change your thinking a bit from "big models" to "small airplanes".

I powered it with a soft-mounted ST 3000. Soft mounting the engine and balancing the propeller makes the biggest difference in saving an airframe, in my opinion.

Daren

[This message has been edited by Daren (edited 05-15-2001).]
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