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Old Sep 24, 2012, 07:36 AM
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makind's Avatar
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What could be cause of this crash?

Hi.
Friend of mine was trying new build plane.
But immediately after lunch the plane rolls left and nose up.
The plane should have correct CG (its more nose heavy) and trims are neutral in first take of, on second take of ailerons are more to right turn. The plane is balanced in horizontal line (neither wing is heavier than the other one)

Im more into building than flying so i can not help him. But my guess is wrong motor angle?

Hand lunch was parallel to ground, motor can easily hover the plane. So power is not an issue

Thank you much for reply.


Video from test is here:
FW190 test flight - crash (0 min 9 sec)
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Last edited by makind; Sep 24, 2012 at 08:06 AM. Reason: added some informations
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Old Sep 24, 2012, 08:03 AM
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I am a noob, but i would say, terrible hand launch for a start and the motor is either way underpowered or not enough throttle, it rolled left probably due to a combination of the poor throw and torque roll. oh and at 0:04 the aileron on right wing is up.
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Old Sep 24, 2012, 08:05 AM
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Originally Posted by jack3auer View Post
I am a noob, but i would say, terrible hand launch for a start and the motor is either way underpowered or not enough throttle, it rolled left probably due to a combination of the poor throw and torque roll.
It looks on the video on wrong lunch, but the hand lunch was parallel to ground, motor can easily hover the plane. So power is not an issue.
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Old Sep 24, 2012, 08:12 AM
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Originally Posted by makind View Post
It looks on the video on wrong lunch, but the hand lunch was parallel to ground, motor can easily hover the plane. So power is not an issue.
he appears to throw it up and the last second though, perhaps someone else with much larger knowledge than me (everyone on here lol) will be able to help.
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Old Sep 24, 2012, 08:17 AM
An itch?. Scratch build.
eflightray's Avatar
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Joined Mar 2003
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Agreed. The launch was probably 80% of the problem, the rest ?, probably it just din't have the will to fly.

A model should be able to fly away level with just a gentle straight launch and probably 30% throttle, (unless it's built like the proverbial brick outhouse).

When you consider how well many of the electric lightweight models glide, full power, (often the cause of the left roll), just shouldn't be necessary for a launch. It looks like the site has some reasonably tall grass, try the basic glide test to see if the model wants to fly straight power off.
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Old Sep 24, 2012, 09:17 AM
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dedStik's Avatar
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Which way was the wind coming from? Was he launching into the wind?
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Old Sep 24, 2012, 09:32 AM
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It's the hand launch. Note in the video that the fingers are still gripping/touching the left side of the plane after his thumb has let go of the right side. As the plane moves forward, the fingers are exerting a twisting force on the left side, causing the plane to roll to the left. The prop torque is probably also contributing some as well, but if the launch were correct the problem would be far less pronounced.

Try launching the plane by resting the bottom center part of the wing on the extended thumb and fingertips with the left hand and pushing from the tailpiece with the right hand. Throw the plane straight ahead like a spear and NOT angled upward. It should take off correctly.

Best of luck!
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Old Sep 24, 2012, 10:20 AM
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Originally Posted by dedStik View Post
Which way was the wind coming from? Was he launching into the wind?
no wind at all
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Old Sep 24, 2012, 10:22 AM
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Quote:
Originally Posted by BigIron357 View Post
It's the hand launch. Note in the video that the fingers are still gripping/touching the left side of the plane after his thumb has let go of the right side. As the plane moves forward, the fingers are exerting a twisting force on the left side, causing the plane to roll to the left. The prop torque is probably also contributing some as well, but if the launch were correct the problem would be far less pronounced.

Try launching the plane by resting the bottom center part of the wing on the extended thumb and fingertips with the left hand and pushing from the tailpiece with the right hand. Throw the plane straight ahead like a spear and NOT angled upward. It should take off correctly.

Best of luck!
i will suggest this to him for the next lunch, thank you
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Old Sep 24, 2012, 02:34 PM
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Quote:
Originally Posted by BigIron357 View Post
It's the hand launch. Note in the video that the fingers are still gripping/touching the left side of the plane after his thumb has let go of the right side. As the plane moves forward, the fingers are exerting a twisting force on the left side, causing the plane to roll to the left. The prop torque is probably also contributing some as well, but if the launch were correct the problem would be far less pronounced.

Try launching the plane by resting the bottom center part of the wing on the extended thumb and fingertips with the left hand and pushing from the tailpiece with the right hand. Throw the plane straight ahead like a spear and NOT angled upward. It should take off correctly.

Best of luck!
I talked to the guy and he was swearing that he lunched the plane as straight as possible. He has other planes also and only this one had problems.
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Old Sep 24, 2012, 02:54 PM
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Video shows the right aileron is warped. Control surfaces should be straight. Condition of the other surfaces are not apparent in the video, but if the right aileron is an indication of the quality of that model, the other control surfaces will be suspect. I personally will not attempt to fly a model with warped control surfaces.

It is evident from the video that the model stalls from moment of hand launch, then crashes, in all the attempts. Pilot had no control over the model at all, perhaps because of the warped controls, which causes the nose high (then the stall) or the snap to the left (which looks like an obvious stall).

Motor/prop may be generating enough thrust but to fly, a plane needs to attain proper flying airspeed. So perhaps plane has not yet attained whatever air speed it needs to fly (under control).

Perhaps that particular model was a bit too heavy for its design. Not enough data was supplied.

Even if the motor/prop produces enough thrust to prop-hang the model, the model will only hover (as in 3D) if the model and radio are set-up properly and under the control of a competent 3D pilot.

Planes will not hover by themselves.
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Old Sep 24, 2012, 02:54 PM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
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Which supplier's/manufacturer's FW 190 is it ?

There is sure to be threads on it somewhere, and they may have any tips and tweeks needed if there is a launch problem.
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Old Sep 24, 2012, 02:57 PM
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Quote:
Originally Posted by easyrider604 View Post
Video shows the right aileron is warped. Not sure if that is a contributory factor though. Condition of the other surfaces are not apparent in the video, but if the right aileron is an indication of the quality of that model, the other control surfaces will be suspect.

It is evident from the video that the model stalls first, then crashes, in all the attempts.

Motor/prop may be generating enough thrust but to fly, a plane needs to attain proper flying airspeed. So perhaps plane has not yet attained whatever air speed it needs to fly (under control).

Even if the motor/prop produces enough thrust to prop-hang the model, the model will only hover (as in 3D) if the model and radio are set-up properly and under the control of a competent 3D pilot.

Planes will not hover by themselves.
The aileron is offset for compensating the left roll.
But the airspeed could be the problem.
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Old Sep 24, 2012, 02:58 PM
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Originally Posted by eflightray View Post
Which supplier's/manufacturer's FW 190 is it ?

There is sure to be threads on it somewhere, and they may have any tips and tweeks needed if there is a launch problem.
Its home build plane from foam.

First tests.
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Old Sep 24, 2012, 03:09 PM
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Looks like he waited too long to start feeding in DOWN elevator. Was probably giving it up elevator the entire time and she stalled...

Throttle controls ELEVATION, elevator controls SPEED... unless ,of course, you have 1:1 or more thrust to weight..which he obviously did not
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