Taking off in a straight line!!

Can anyone answer this question?

When a model is taking off under max or near max power, it veers to the left. This is invariably explained as a result of torque reaction from the prop and is countered with right rudder.
The question is how does a torque about the roll axis, (prop reaction) get translated to a torque about the yaw axis, (veer to the left) when both wheels are firmly on the ground preventing any roll movement?

Have a google for P factor.

Thanks Alan

There is quite a lot on the subject.
To minimise the effect, the implication is to raise the tail as quickly as possible with a tail dragger and keep a tricycle layout level for as long as possible. Also with a trike undercarriage, the plane will only veer left when the nose is raised to lift off.

Is this true?

Could this effect also generate a pitching torque from a side wind?

You're right Ron , there is a huge amount on the subject of P factor, Gyroscopic precession, spiral slipstream and torque effects.

Logically P factor must always have an effect anytime the prop disc is at an angle to the airflow. How much effect that has on the aircraft must depend on what other forces are acting at the time.

For a tail dragger at take-off I would imagine that gaining forward speed as quickly as possible without tipping the nose would be the way to reduce the yaw effect.

For a trike, by the time the nose is raise you already have a reasonable air speed so P factor and spiral slipstream effects are already reduced relative to the aerodynamic forces provided by the wings, tail plane and fin.

A question for the experts: What effect does P factor etc have when doing a stall turn?

Alan asks

A question for the experts: What effect does P factor etc have when doing a stall turn?

I don't profess to being a particular expert but I would have thought that, since at the point of ruddering over in a stall turn, the motor will be close to idle the effect would be negligible.

I guess it's a no flying day when we're pondering things we have no control over?

ronp849 wrote: Can anyone answer this question?

When a model is taking off under max or near max power, it veers to the left. This is invariably explained as a result of torque reaction from the prop and is countered with right rudder.
The question is how does a torque about the roll axis, (prop reaction) get translated to a torque about the yaw axis, (veer to the left) when both wheels are firmly on the ground preventing any roll movement?

Torque reaction does affect the direction during take-off BUT by far the major cause is the anticlockwise (looking from the front) rotating slipstream from the prop. which strikes the vertical stabiliser / Rudder which on 99% of aircraft is above the centreline. Then there is nothing below the centre line to counteract the effect (an exception being the Dornier 335)