RCU Forums - taking off

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wen im taking off, and my plane twists to the left, shuld i use rudder, or aileron to get it back straight, and how much shuld i us

thanks, daniel

Using rudder, especially around the landing strip, is great practice. Not enough people use rudder, or at least use it enough. You should be using rudder to keep in line with the strip on landing, so why not use it to keep in line on take off? Now if your plane is really rolling as it pulls to the left, then of course aileron will be needed to keep the plane level.

Good question. This is obviously my opinion, so it will be interesting to read the other responses.

It depends on what you mean by "twist". If the plane is turning left or right, then yes you want to use the rudder to correct. But if the wings are dipping as in a roll, then you want to use the ailerons to correct it.

Ken

thank u 4 ur advise, it shuld help me not crah on take-off agian

Does your plane "twist" while still on the ground? If so, then you need to apply rudder to correct. Are you familiar with the terms "roll", "yaw" and "pitch"? When taxiing on the ground, your model can only "yaw" left or right. Yaw is when the nose of the model turns left or right. Pitch is when the nose points up or down. Roll is when the nose stays put but when one wingtip goes up and the other goes down. This is also called banking. Roll, or banking, you correct with the ailerons.

If your model is turning (yawing) suddenly after taking off, then your nosegear or tailwheel is misaligned.

dont worry, i now the terms, im a pilot (of a cessna 172), but im new to model airplanes.

Quote:

ORIGINAL: daniel pedersen

dont worry, i now the terms, im a pilot (of a cessna 172), but im new to model airplanes.

"Model Airplanes" follow the same rules of aerodynamics and principals of flight as full scale planes do. If you are a full scale pilot flying a Cessna 172 then you should apply the same controls for your RC plane as you would the full scale on that you fly.

Ken

gtotcha, but when i watch videos of rc, they do alot more than my cessan, thay hover, like come on, when do you see a real plane hover, so i thought that maybe rc was way different, thank you for ur insight to my problem

Quote:

ORIGINAL: daniel pedersen

gtotcha, but when i watch videos of rc, they do alot more than my cessan, thay hover, like come on, when do you see a real plane hover, so i thought that maybe rc was way different, thank you for ur insight to my problem

You are referring to 3D flying. Those types of manuevers are different from full scale flying, but basics such as taking off the controls still do the same thing.

Ken

Full scale flight doesn't help with R/C much. When was the last time you flew a full-scale airplane while it was heading AT you?

If it's a nose-wheel trike have you ground-checked it so it rolls straight with the rudder centered? Common error is to have the nose wheel out of line with the rudder so they fight each other. The nose wheel has a lot more authority while in contact with the ground, but the instant you rotate if it is not set to the rudder the model suddenly turns when the rudder gets the airflow to be in command.

There is also a natural tendency to wander to port from the prop torque. Taildraggers, and in particular narrow carriaged biplanes need a bit of right rudder to compensate. Feed in throttle smoothly and gradually. Flooring it gives a lot of torque before the windspeed over the control surfaces gives you any control authority.

Quote:

ORIGINAL: Charlie P.

Full scale flight doesn't help with R/C much. When was the last time you flew a full-scale airplane while it was heading AT you?

If it's a nose-wheel trike have you ground-checked it so it rolls straight with the rudder centered? Common error is to have the nose wheel out of line with the rudder so they fight each other. The nose wheel has a lot more authority while in contact with the ground, but the instant you rotate if it is not set to the rudder the model suddenly turns when the rudder gets the airflow to be in command.

There is also a natural tendency to wander to port from the prop torque. Taildraggers, and in particular narrow carriaged biplanes need a bit of right rudder to compensate. Feed in throttle smoothly and gradually. Flooring it gives a lot of torque before the windspeed over the control surfaces gives you any control authority.

I thought I was having some similar problems - what turned out is that my nose wheel was keeping the plane straight on the ground, but when it left the ground I got the 'wind (something) effect (can't remember the name of the stupid thing) where the wind pushed my vertical stabilizer so the nose pointed towards the wind. Rudder to correct this.

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ORIGINAL: gaRCfield

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Did you use trim to straighten out the roll on the ground?

If you did, then you've essentially trimmed in some yaw in the rudder in order to get the nosewheel straight. Rather than using trim to adjust the nosewheel for a straight takeoff run or roll out on landing you should use the nose wheel linkage to adjust for straight roll. This leaves the rudder trimmed properly so you don't see a sudden yaw as the rudder gains effectiveness either while still on the ground or just at take off.

My rudder/nose gear servo has a "slide through" type linkage at the servo for the nose gear pushrod. That allows me to loosen the set screw and move the pushrod forward or backward to straighten the nose wheel, while not affecting the rudder at all.

Bob

Quote:

ORIGINAL: mitchell170
Did you use trim to straighten out the roll on the ground?

If you did, then you've essentially trimmed in some yaw in the rudder in order to get the nosewheel straight. Rather than using trim to adjust the nosewheel for a straight takeoff run or roll out on landing you should use the nose wheel linkage to adjust for straight roll. This leaves the rudder trimmed properly so you don't see a sudden yaw as the rudder gains effectiveness either while still on the ground or just at take off.

My rudder/nose gear servo has a "slide through" type linkage at the servo for the nose gear pushrod. That allows me to loosen the set screw and move the pushrod forward or backward to straighten the nose wheel, while not affecting the rudder at all.

Bob

Nope, did as you said, adjusted all with either the set screw or the linkage on the servo horn (one of those slide through setups) so the rudder would stay as trimmed for flight. My instructor saw me and saw it happened, and noticed the wind, and said my plane was 'weathervaning' (that's the term, now I remember!). But yeah, as soon as the front wheel left the ground, the plane would turn right into the wind. Fun stuff.

Quote:

ORIGINAL: daniel pedersen

wen im taking off, and my plane twists to the left, shuld i use rudder, or aileron to get it back straight, and how much shuld i us

thanks, daniel

If it rolls, use aileron.

If it yaws, use rudder.

Use enought to straighten it out.