My friend and I both have NexStar trainers. In order to have the plane fly straight, we both have to trim the ailerons to the left (so much so that my friend had to adjust the clevises 2 full turns in the proper direction for the ailerons, cause he didn't have any more play with the trim adjustment on his radio).

We are both beginners and when we takeoff and just get in the air, the plane seems to wanna go to the right all the time. This happens no matter which direction the wind is coming from (just thought I'd mention that even though we take off into the wind anyways). Our instructor has our planes trimmed so they fly straight, it just seems to be a problem when we takeoff( this dosen't seem to be a problem when the instructor does the takeoff ). My instructor says that we have to give additional left aileron input when we takeoff.

Is the fact that the plane naturally pulls to the right, enhanced on takeoff (even though the trim is set to have it fly straight?) Might this be why we seem to have to give additional left aileron input on takeoff.

I've noticed that on a few of those on our training nights.. I think they just like to go to the right, however, I'm interested to hear others responses.. [&:]

Do these planes have the "gadgets" on the wings. The anti-spin leading edge cuffs and the drag flaps? Is the AFS on or off or even installed?

Trimmed to fly straight is very different from taking off. There are several issues here, engine torque being one of them. Rather than doing anything to the ailerons during take off other than to keep the wings level, try a little left rudder once the wheels leave the ground.

For normal flight, the trim will vary slightly from flight to flight depending on how things are mounted. Once the ailerons are trimmed for straight flight, they pretty much will stay there with only a couple clicks from time to time, usually on the first flight of the day. The elevator trim, however, works only for one throttle setting. If you add more throttle, then probably will require some trim to get straight and level flight. But that's not your problem, is it. Try a little left rudder rather than ailerons (unless the plane is banking.. which is different from turning).

DS.

In a real plane...ie...Cessna 172, on take-off you need to use right rudder 'till you pick up speed and level out, so a model plane would probably act the same way. Maybe in a different direction, but same principal

The plane does have the wing droops installed. My instructor had me remove the drag flaps and disabled the AFS before he even touched it.

The right turn comes from the right-thrust built into the firewall & the left engine offset, as it is factory mounted. It gives the correct engine offset & thrust angle to make the plane track straight at ~ 1/3 - 1/2 throttle, where beginners will be doing much of their flying. The right thrust is excessive for full power operation (like take-off) and must be countered with a bit of left rudder (not left aileron) until the throttle is backed off to low-medium cruise power. Your instructors can easily handle this situation (maybe even hardly notice it), but it is a challenge to some students.

The mechanical "fix" is to straighten the right-thrust by shimming the right side of the engine mount, but don't bother "correcting" the engine offset (it is mounted left of centerline).

As I noted in another thread, the NexStar flies perfectly well with zero right thrust & zero engine offset -- but it will pull left on take-off when configured that way.

rt rudder on TO is essential not too much its p factor and engine torque

You would be partially correct (right rudder needed) in most cases, but in the case of the Nexstar, LEFT rudder is needed to counteract the excessive RIGHT THRUST at full power.

P-factor does not come into the equation for tri-geared aircraft, as they sit essentially level during take-off. Engine torque produces a ROLLING force & it also doesn't affect take-off appreciably, unless the aircraft is yanked off the ground at a low airspeed (P-factor will also have a small effect in this case, because of the high angle of attack). P-factor has a small effect on tail draggers while they accelerate with their tails down

What does give a LEFT TURNING FORCE is the spiral slipstream from the propeller, striking the rudder & fin assembly from the left side, & hence, pushing the tail to the right.

The effects of engine torque can be seen when a slow flying aircraft (with a powerfull engine) suddenly has full throttle applied -- it will try to roll to the left from the torque & turn to the left from the induced bank, plus the accelerating spiral slipstream.

britbrat,

That is, perhaps, the single BEST explanation of P-factor and engine torque I've ever seen. AND, as a bonus, it clearly identifies why the effect is greater with taildraggers vs. trikes.

Well done, sir!

I am a full scale 172 driver N318RC p factor is involved in all prop aircraft. As the engine rotates counterclockwise the load on the prop is huge. P factor is the uneven force from the blade rotating forward and then back. You apply rt rudder always on to. A trike setup is easier to handle on the ground whereas a tail dragger requires a delicate balance of elev. rudd. and power. I have been flying rc for 30 yrs and full scale for 5. Ive heard the nextstars are not all they say they are ive never flown one as i fly WWII fighters mainly. my current proj is a pcm tristar turbine. about 10,000.00 in that project.
Maybe his plane is out od trim or the wing is not on straight. Use thread to see if wing is square on the fuse good luck

Can you tell me why Spanish built ME-109's (actually M-109) need left rudder on takeoff? WW-II vintage.

There is a reason, let's see if you know it.

They were powered by RR Merlins

they required immediate and simultaneous application of left rudder and throttle. very narrow gear. They were not powered by merlins (some spanish air force io9 were) they used dailmer benz engines. rotation is oppisite a griffon , allison , or merlin.

Correct. The Confederate Air Force had a Spanish built plane that they put a German motor in. Since the vertical stab was offset in the wrong direction it took enormous rt leg pressure on takeoff to make it go straight and almost full trim (right) in flight. They eventually got a correct engine, from what I understand.

I've been flying FS aircraft for 50 yrs & models for 56, I'm also a fluid dynamics engineering specialist. P-factor is a minor force. It only occurs at positive or negative angles of attack (negative angles of attact are uncommon, brief transients). In a significant positive AOA, wherein the descending blades on the starboard side of the aircraft are at a greater AOA than the ascending blades on the port side, the starboard side blades consequently generate more thrust -- pushing the nose to the left. In normal cruise, where the AOA is close to zero, P-factor isn't even there as a sensible force.

The most powerfull force perturbing the yaw axis is the spiral slipstream, which is present in most flight regimes. Torque perturbs the roll axis (& indirectly the yaw axis), but is only a truly significant factor during acceleration at low speeds. It can be nearly overwhelming in the case of a very powerfull single engined AC (Griffon-engined Spits, Thunderbolts, Corsairs etc.) if the pilot is unprepared. P-factor is also more powerfull in those cases. The best example of a significat P-factor effect that I can think of is the case of the prototype & Mk I Spitfires, with coarse fixed-pitch 2-bladed propellers. They tried hard to turn left on initial take-off role -- from the combination of P-factor & spiral slipstream.

The Spanish Hispano Aviacion versions of the BF-109 were powered variously by by Hispano-Suiza HS 12Z-17's and by the RR Merlin 500-45. The Czech Avia CS 99 & Avia S199 were powered by Jumo 211F engines.

its also why corsairs have a tail wiggle. no fairing between fuse and wing. You are correct p factor is a bigger problem on acsent and descent however it is always present even in minor form

Getting back to the Nexstar -- The right thrust is very substantial & the engine is also offset to the left -- which gives a RIGHT turning force. I fly NexStars several times a week & I've modified many, including constructing a number of NexStar hot rods.

If the right turn on take-off is bothering you -- ditch the right thrust & have fun.

before you get too deep in theory, take a look at the bolts holding the engine mount to the firewall and the bolts holding the engine to the mount. If the firewall bolts have loosened, the plane will pull to the right big time on take off. It's worth a look.

DaveB

Thank you all for the replies. DaveB I will check the bolts as I haven't checked them in a few weeks.

Much appreciated

jsixpack1......I too have a nexstar. Took several fixes to the plane to get it to take off properly. I'm sure these guys know alot more than I do ...... as I am still a newbie at this sport. What fixed my take-off problems was FIRST.....make sure the front wheel is
EXACTLY lined up with the rudder. I had to grind the shaft a couple of times to get this to STAY WHERE I SET IT.........NEXT........
(and I think this really helped) I changed the wheels to a harder rubber wheel and increased the size to 3 1/2" wheels. I think the tire size change also made my landings smoother once on the ground.

I know this is basic stuff and Britbat seems to know alot about this bird.....so not taking anything away from what he says......I'm sure he
knows what he is talking about for sure....just sometimes I tend to overlook the obvious and make it some things harder than they really
are.

Just a thought here.....