PLease don't trim the rudder for straight take off, you don't know what the plane will do once it gets in the air.

If your rudder is atached to the tail wheel such as mine,a 16th of a inch trim will hardly affect take off just be sure your plane can go a little to the left if needed.I do this all the time when I use the park street for a run way,so I dont smash into the curb.

As several have stated above, it is best to solve the problem by learning how to use the rudder instead of bandaging the problem.

Thank you Richard, that's what I have been trying to say.

I will soon be flying my first RC aircraft, a piper cub I am building from scratch, I expect to experiance these same problems. as I have flown the real ones, definatly learn to use the rudder. I would sugest really long take off runs, but dont take off. just practicing getting to the point where the plane is light and jittery on the wheels, and then roll back on the throttle to settle back down. this will get you more familiar with keeping it straight at the most critical point in flight. and if stuff goes wrong atleast you still have the fuse and all radio gear. worst it can do is roll over.



--------------------------------------------------------------------------------------------------
remember no matter how forcefully you plant your balsa, a tree will not grow.

Mystic,
Your choice for a "first" airplane is not the best around. Especially if you have spent a large amount of time scratch building it. You really should get a trainer and an instructor. Learn to fly R/C and then you will have the chance to enjoy your Cub.
I see you have flown full scale, and that is one more strike against succsess. Any modeller who flys full scale will tell you that the models are much harder to learn.

Maybe, but, I fly full scale and I taught my self to fly RC. I already know what it takes for a plane to fly, glide, loop, turn and land. I just had to learn how to change from being behind the plane, to the side of the plane, to the front of the plane. Once I got that whipped I had no problem.

just a side note, I am expecting to plant this one, and prolly another or 2, but I enjoy building them anyway. should I sheet the wing in 1/32 balsa from the main spar back? I know it will increase wing loading slightly but wont I get a better wing?

[8D]
Right from the beginner handbook of first phases of flight instruction.

Left turning tendancy in an aircraft are imposed by:
Torque reaction
Spiraling slipstream
Gyroscopic precession
Asymmetric propellar loading (P-factor)

That's why it happens but knowing why will just explain how. In a tail dragger the plane does not stop flying until it stops moving.

Wake up that left thumb and apply the proper rudder pressure to maintain the centerline during the takeoff roll.

Let's not take this thread off topic. I already answered this question in your thread.

I have to agree with others; do not make "corrections" to the airframe, like changing the right thrust, or off-setting the tail wheel, simply use your left thumb the way it was intended to be used.
Dennis-

Oh thats what my thumb is for, OK let me pull it out

People seem to think the rudder is for "show"...its a primary flight control that is useful on the ground. Go figure. I answered the question. WAKE up THUMB!!!!!!!

You may plant it a lot quicker than you realize and never get the chance to learn a thing from the experience. I agree with TLH101, get a cheap trainer and some help before you put that Cub in the air. Knowing what each flight surface does is something every beginner can easily be taught, don't be fooled into thinking you have an advantage due to being a full scale pilot. Not sure what you mean by a "better wing." Sheeting isn't necessary aft of the spar on that plane and will only add weight. The plane will fly just fine with covering only.

i didnt bother readin everyones thread so if this idea has been posted then i am sorry.. anyways try off setting the motor a few degrees in the op direction it is turning, maybe it will help or maybe it wont, just an idea,

or try positinog the wheel to the right so when it takes off its going straight like trim maybe?

The way I was taught was to run the fuselage up and down the runway without the wing on the airplane. My instructor made me do this until I could keep it on the yellow center line at full throttle before he let me attempt a takeoff. This accomplished two things; it forced me to " wake " up that left thumb and also to not try to steer the plane on the ground with the ailerons which is a common error for newbies.

The correct solution to this problem is to learn to use the rudder, but
there is one airframe modification that could be worthwhile. The strongest
effect causing your plane to veer left is the 'spiral slipstream'. The air
blown back by the prop has strong swirl. When this swirling flow strikes
the vertical stabilizer, it pushes it right, which steers the plane to the
left. This effect is generally stronger than P-effect in any case, and in
this case we know it is, since the tail on a tail-dragger picks up, making
the angle of attack of the plane small. One way to minimize the steering
effect of the swirling flow is to add some fin area below the center line
of the plane, so that some of the swirling flow hits it from the right. You
could remove some area from the top of the fin as well. A fin with the
same amount of area above and below the center line will almost eliminate
this swirl-induced steering. To reduce the strength of the swirl, you could
also consider a prop with less pitch.

Because the fin is more effective at stabilizing the plane at high speed,
is also helps to throttle up gradually, as the plane accelerates. This way,
the 'weather vane' effect of the fin increases as the swirl increases, so
you don't need to use as much rudder. A typical full throttle takeoff gives
you the maximum amount of swirl in the prop wash right at the beginning,
when the fin doesn't help you out at all.

banktoturn

Everybody flys like they have a two channel airplane, just using the right stick. But the rudder should be used all the time in all flight conditions with the possible exception of straight and level flight. Although you may not have noticed, when doing an inside loop, a slight amount of right rudder will improve the track of the airplane, while left rudder is required to track through an outside loop. Now that you have you thumb on that left stick, a bit of throttle management comes in handy too. Slow down the airplane and experience snap rolls and stall turns.

The rudder and ailerons are useful with crosswind takeoffs and landing. Use the rudder to maintain direction control on takeoff, but use the ailerons to hold the wing down into the wind. That way, you will look good, and you won't scare the crap out of the people on the line that are upwind of where you start your takeoff roll. Fly the airplane, don't just herd it.

va,

How does gyroscopic precession affect fixed pitch propellors and takeoffs?

This theory is based on one of the gyroscopic properties which apply to any object spinning in space,even a rotating airplane propellar. As the nose of the airplane is raised or lowered, or moved left or ight, a deflective force is applied to the spinning propellar which results in a reactive force known as precession. Precesssion is the resultant action or deflection of a spinning wheel (propellar) in thiscase when a force is applied to its rim. This resultantmforce occurs 90 degrees ahead of the directon of rotation, and in the direction of the applied force.

On take offs the load is greatest because the maximum amount of power is applied with increasing foward motion. The effects are counteracted when foward velocity increases and the rudder dampens or cancels this action.

OK, thanks for all the input. I am not going to try and tell you that I understood everything that has been discussed, but I did get out today, beautifult day - clear blue skies, 5mph wind and a cool 10 degrees! I did move the landing gear back 1/2 an inch and no more ground looping. Anyhow, the rudder control works, and I actually made some fairly acceptable takeoffs, not the prettiest, but a lot more stable..... until the last one! The wind started to pick up, so I had a little more right rudder, then she lifted off nicely, only to do a beautiful arc to the right, then continue on over to the ground! Spectacular cartwheel, fortunately only a broken spinner and a slight crack at the base of the rear stab. Thank goodness the wing is attached with rubber bands. I can certainly attest to the strong construction of the SIG Kadet Mark2!

Keep on it Ozzie, you'll get the hang of it. Geez you went flying today? I froze my keester off just walking to my car.

Glad you got the tail dragger takeoff thing whipped. I never believed that I would prefer them, but I do now.

VA- thanks. I never thought of it in those terms, but it makes sense. I was a helicopter pilot in the service and I know how it applies when changing pitch in the rotor system. That's why I asked. Anyway, thanks for giving me that to think about for a while.

Sounds like you forgot to ease the rudder back to neutral as the plane left the ground. Keep at it, you'll get it.

Ah taildraggers, interesting beasts.

I'd agree with others that the Cub is most definitely not a good trainer. Initially it seems like it should be, but it's not. When you're learning R/C, orientation is the key concerm and the main challenge, IMO. You need as little trouble with "managing" the plane (speed management, coordination, etc) as possible, you will already be busy keeping straight on the basic control inputs (not "should I add some more rudder?", but stuff like "LEFT OR RIGHT????? AAHHH!!!!" ).

However, as I've said before, Cubs make awesome "second trainers". Once you've got proficient at the trainer and maybe a sport plane or two, you can get a lot of valuable experience from a Cub. I always thought my Tiger flew fine with no rudder input, but after getting used to my Cub, I find myself constantly using rudder on the Tiger.

The Cub also rewards consistent patterns and smooth, coordinated flying. It just begs for scale-like flight.

Once you've mastered the basics on something simple, a (reasonably accurate) Cub will almost certainly make you a better pilot.

-Matt Bailey

i think somebody already said it but you got to have toe in an check it after a hard landing it my have been bent