I seem to still be having problems trying to control my plane whilst attempting some practice take off runs. I have moved the control rod so it was closer in on the servo arm to reduce the travel of the front wheel when turning. But once I build up some speed the plane starts to weave from the left to the right as I try to keep it straight.
A mate of mine first noticed a problem that one wheel could turn more freely than the other so we freed up the other wheel but it didnt seem to fix the problem. The plane will pull slightly to the left but when I try to correct it, it seems to then want to pull to the right.
It seems as if the steering is less responsive since I moved the control rod closer on the servo arm and so takes longer to correct itself when I apply opposite stick. But if I move it back then it is to sensitive. Do I sounbd confused??? Thats cause I am.

Does anyone have any suggestions for this?

Thanks,

Troy.

You may have a common problem called toe out. Look at the main gear wheels are they pointing straight parallel to one another this would have no toe. If they ate pointed out to the out side this is toe out. Toe out will cause the plane to wander all over the runway and get worse the faster you go. The best setup is to have a degree or two of toe in it just needs to be the same on both sides. The toe in will cause the plane to track straight even when you ad at top speed just before take off.

Troy,

P-factor will always pull your model to the left. It is your job to apply the correct amount of right rudder to keep your model tracking straight. The amount of right rudder needed will vary and getting it correct simply takes practice. You have to watch the model and make corrections as needed. Simply adding some right rudder and holding it constant most likely won't be enough.

When I was learning to take off I had a similar problem. During the take off run the model would be all over the runway. My solution to this problem was to not simply jam the the power to full and "hang on" until the model left the ground. This "full power, hook left, and hang on" technique appears to be used by many at my field. It's not too back when the pattern is such that the model hooks left away from the pits. However, when the wind changes and the left hook carries the model over the pits then we have a problem... I have found that if I go to about 1/2 throttle and let the model run on the ground I have more time to react and get it all straight and stable. Then once it is stable I can add whatever additional power is needed to get the model airborne. This is the technique that I am teaching my students and so far it is working pretty well.

I hope this help.

Thanks guys for your responses. They are both great ideas which I will try. I will check to see if my wheels are toeing out and fix if neccasary. Galen what your saying is exactly right I am applying full throttle and trying to hold the plane steady. I will give your technique a try and see if I can control the plane better. Thanks again.

Troy.

Troy,

Galen is on the money, slowly increasing the throttle gives you a better chance to keep it straight. The other problem folks have is over controlling, hence the weaving. Think about PRESSURE on the stick opposite to the p-factor rather than turning the plane. Also, good solid nose gear like the Fults strut helps alot also.

Best of luck

What plane is this? What size of wire is in use? A guy at my field has a problem with one plane where the front gear wire was too thin and made it unstable during takeoff. It was an f-20 with a .46 on a pipe. Made for some excitement!!!

I also agree with Galen the GLH (Go Like He!!) method helps get air to flow over the rudder which also helps to keep the plane on track.

This sounds more like a toe or lose nose wheel problem that a P-factor problem. Remeber that the original post mentioned that this was the nose wheel that he reduced the travel of. This indicates that it is a trike.

As I understand it (mind you, I am not an aeronautical engineer by any stretch) P-factor has to due with the angle of attack relative to speed and change in rpm. If you have you TAIL-DRAGGER sitting on the field, there is a significant difference in the angle of attach for the right side of the plane than the left. Hmmm...the prop going in the down direction (which is on the right side of the plane) is grabbing more air, as it has a greater relative pitch to the forward travel of the plane. The up (left) side is grabbing less air. The result of this is that if you JAM the throttle, the plane will jump to the left. You can produce the same effect by slowing a flying plane to stall with the nose up and jamming the throttle WHILE THERE IS STILL A GREAT ANGLE OF ATTACK. Again, the plane will jump to the left.

You do not see this with a trike, as the plane should not have a difference in the angel of attack (ie, the tail is not on the ground). Finally, let's not forget that there is a bit of effect from engine torque causing the plane to head left.

All this being said, by rolling into the gas as opposed to laying on it, you realize less of an effect from P-factor. This is why we all learn to roll into the gas when taking off in a tail-dragger.

just my understanding of it all. If somone knows more about this, please let me know.

Zee

This was one of the hardest things for me to learn. I was always very nervous on take offs.

I like the idea of putting the throttle to halfway and then let your brain can catch up with the speed of the plane and steering. Then, after you get the plane going straight, slowly increase the throttle, pull back slowly and "Up, up and away"!

Of course this depends a little on how long your runway is!

Mike

Check your rudder throw as well. May be too much.

When you take off are you standing behind the model? Easier!
or standing in a flight box on the flight line? HarderThe advice to open the throttle slowly was the best. If you jam the throttle open and hope , you may end up taking off cross wind. Not a good idea for a learner.You may also want to consider raising your nose on the front strut. (lengthen your strut) this will give you a slight possitive angle of attack and thus take some weight off the nose wheel as you gain speed. Too short of a front strut will tend to dig your nose in as you gain speed. Hope this helps

I agree with standing behind only if you are the only one flying.

troyp:

what type of surface are you practicing on??

What you can also do is to adjust the thrust of the plane (engine) so that you have less p-factor effect. Changing your propeller will also make a difference.

From what I have read, adjusting the engine to correct for p-factor is a bad idea. However, many plane that I have seem (remember I am quite new at this) have 1-3 degrees of left angle either established by the firewall or the mounting of the engine. Some will also have some down angle as well. My understanding is that the left is for engine torque and the down for p-factor, but I would not stand on that statement.

As for what you do to correct for p-factor...don't jam the gas, but roll into it. Correct for the left with some right rudder. The only time it is really a problem is when you are taking off.

The trainer I first learned to take off with was a hangar-9 easy fly 40 that had been converted to tail dragger. The instructor was so used to the left turn (it was his plane), he forgot to tell me to put some right rudder to it. I almost had the ting turned back towards us before he cut the gas and told me what happened. Then he showed me to roll into the gas and give it right rudder until you get the tail up. Once you have that, she flies like normal.

Zee

If you are flying from a grass field, you will always have a little drift, due to the blades of grass hitting the wheels. When you correct a drift just give a little stick in the opposite direction, as soon as you see a hint of it going the other way, neutralize the stick. Do not run it any farther on the ground than needed to lift off. The faster it gets on the ground, the worse the drift will be.

Hold it on the ground just long enough to get to flying speed. It is the best way.

P-Factor is most pronounced with these conditions: low airspeed, high AOA, and high power.

Left turning tendencies of airplanes: P-Factor, engine torque, gyroscopic precession, and spiraling slip-stream.

You always have to hold a little right rudder when you start down the runnway because of the P factor.

Thanks everyone for the advice but what exactly is P factor?

Troy.

P factor is the tendency for the aircraft to yaw left as power is applied. You have to have right thrust to correct this. Usually it is preset for the engine specified in the plans. Many times you have a larger engine than specified by the plans and you have to make adjustments to the thrust angle to compensate for the increased torque.

I agree with the P-factor stuff - I instinctively give a touch of right rudder, but if he's weaving... I believe the previous poster that mentioned toe-out it correct. Toe-out will really screw up ground handling.

On a ticycle gear airplane, P-Factor doesn't come into play until you actually rotate the nose to take-off attitude. On the ground, during the take-off run, it's torque and spiraling slip-stream.

Since you're running with a trike configuration, I agree that it's probably a "toe-out" problem, and p-factor shouldn't come into play.

Here's a little trick I used back when I first learned take-offs.

Remove the wing, and put a plastic bag over the wing saddle instead (only 2-4 elastics needed). This way you can practice high speed handling without fear of the plane taking off. It may look stupid, but not as stupid as crashing when you took off by accident, and weren't ready. This will also maintain pressure on the wheels during higher speed (takeoff speed), in case the weaving is due to the wings lifting the wheels a smidge.

Good luck, and keep practicing...