tried everything?
#1
Thread Starter
Banned
Joined: Jan 2003
Posts: 4,923
Likes: 0
Received 0 Likes
on
0 Posts
From: gone,
Generally... the throws recomended for a trainer are WELL below here the surfaces start to lose effectiveness from excess deflection.
On a typical model, flying about 50 to 80 mph, the control surfaces will still be effective at over 45 deg deflecion. The increase in force on the control system becomes greater compared to the resulting control effect asthe surface is deflected more, up to appx 60 deg, where practically any control surface starts to just be a drag source, rather than having the intended effect.
I doubt that excess travel was the cause of the crash. The description is typical of a model which was stalled, and the elevator pulled hard, before the plane had time to gain airspeed. If the CG was forward, and other conditions were compounding the problems... its easy to have the plane continue in a dive with full up elevator, holding the angle of attack of the wing just right to prevent gaining airspeed to unstall the wing. (one of the few cases where too far forward CG can kill a plane, without preventing take-off.)
On a typical model, flying about 50 to 80 mph, the control surfaces will still be effective at over 45 deg deflecion. The increase in force on the control system becomes greater compared to the resulting control effect asthe surface is deflected more, up to appx 60 deg, where practically any control surface starts to just be a drag source, rather than having the intended effect.
I doubt that excess travel was the cause of the crash. The description is typical of a model which was stalled, and the elevator pulled hard, before the plane had time to gain airspeed. If the CG was forward, and other conditions were compounding the problems... its easy to have the plane continue in a dive with full up elevator, holding the angle of attack of the wing just right to prevent gaining airspeed to unstall the wing. (one of the few cases where too far forward CG can kill a plane, without preventing take-off.)
#2
Senior Member
Another possibility is to flimsy of a push rod on the elevator. The forces on the moveable surface go up with the squre of the increase in velocity. If you have weak or readily bendable push rods, they will bow rather than move the surface. This is especially bad if the push rod is in compression for the "up" command. Keep stiff (heavy gauge wire or wooden dowel) pushrods with very little unsupported length at the end. Many of the trainers have a long section of unguided or unsupported 1/16 inch wire at the rear end which is an accident waiting to happen, especially it the plane is overpowered or you go into a long extended vertical dive.
#3
Thread Starter
Banned
Joined: Jan 2003
Posts: 4,923
Likes: 0
Received 0 Likes
on
0 Posts
From: gone,
Yes, loss of battery power to the RX can easilly cause control problems, including making the servo unable to operate the elevators. 
You wouldn't have happened to check voltage afte the crash.... ?

You wouldn't have happened to check voltage afte the crash.... ?
#4
Member
Joined: Mar 2002
Posts: 62
Likes: 0
Received 0 Likes
on
0 Posts
From: Flint,
MI
Originally posted by Sportflyer
. . . . . . I must have done about 40 high stall torque rolls . . . .
. . . . . . I must have done about 40 high stall torque rolls . . . .
#6
Member
Joined: Mar 2002
Posts: 62
Likes: 0
Received 0 Likes
on
0 Posts
From: Flint,
MI
Originally posted by fhhuber
Because he's a relative beginner... . . . .
Because he's a relative beginner... . . . .
VP
#7
Thread Starter
Banned
Joined: Jan 2003
Posts: 4,923
Likes: 0
Received 0 Likes
on
0 Posts
From: gone,
Only a beginner would say anything about a "high stall torque roll"... There's a snap-roll, which is a stall maneuver... and then the torque roll is done by hanging from the prop, from a hover. There is no such thing as a "high stall torque roll."
#8
Member
Joined: Mar 2002
Posts: 62
Likes: 0
Received 0 Likes
on
0 Posts
From: Flint,
MI
Originally posted by fhhuber
. . . . There is no such thing as a "high stall torque roll."
. . . . There is no such thing as a "high stall torque roll."
VP
#9
Thread Starter
Banned
Joined: Jan 2003
Posts: 4,923
Likes: 0
Received 0 Likes
on
0 Posts
From: gone,
A stall implies that the wing is SUPPOSED to be flying. A torque roll... by definition, the wing isn't flying... its hanging like a dead weight from the fuselage and therefore, from the prop.
How do you stall one torque roll more than another?
No one who knows anything about aerobatics would call it anything other than a Torque roll... adding "high stall" proves lack of knowledge. trying to say its valid to ad that... proves your lack of knowledge.
How do you stall one torque roll more than another?
No one who knows anything about aerobatics would call it anything other than a Torque roll... adding "high stall" proves lack of knowledge. trying to say its valid to ad that... proves your lack of knowledge.
#10
when you say you tried everything on the first crash to stop the dive, then down elevator would have pulled the plane out inverted, if the pushrod siffness WAS the problem. Tone down the throw man.
d
d




