I disconected the AFS in my Nexstar but for some reason once I get airbone it still pulls to one side. I had it checked out by the instructor but everthing he has check is ok. Could it be the servo after it takes off. I had consider buying new ones but that may not help. Any sugestion on what I should do or has anyone else had this problem.

Sounds like you are saying it's rolling on you. Could be several things.
1. Warped wing
2. Out of balance. Heavier on one side than the other
3. Simply out of trim. Either ailerons or rudder.

are you sure your trim on your radio didn't get bumped

Austin

eh, you beat me by 4 seconds[:@]

We checked the balance and it was ok. Now on the wing, how would you check that? They seems go be ok. And on the trims what is the best way to ensure that they are really properly trim correctly?

Proper trim will only be accomplished in flight.

Just disconnecting the AFS may not be all that's needed. Try turning the sensitivity all the way down. The receiver may be trying to make adjustments, based on incorrect signals.

I can usually eyeball most warps, but an easy way is to lay it on a flat table and see if there is any deviation from the root to the tips. Unless there is intentional washout built in, each side should lay flat on the table. It doesn't take much to cause problems - a 1/16" deviation from root to tip will show up in the air. The problem with "trimming out" things like minor warps is the trim you need really varies with the speed of the plane - better to remove the warps and shoot for 0/0/0 on the trims.

Using trim to compensate for warps also causes more drag and causes non balanced throws. Not such a big deal on a slow stable Nexstar, but on something that's got a symmetric wing, no dihedral, and a roll axis near the wing C/L, this can cause the plane to not track straight through a loop and do rolls that are wobbly around its roll axis. I see all kinds of planes out at the field exhibiting these "trimmed out warp" symptoms.

Also check to make sure the wing is on the fuselage straight (wingtips are the same distance from the tip of the rudder for example), and that one wingtip is not higher than the other.

Owned one for 2 years until I sold it to a club member, most the nexstars had 4 degree's right thrust not 2. Put a couple of shims behind the motor mount on the left side as you look at the front and will take care of it. About the thickness of 2 popsicle sticks. It really showed up on take off when you applied full throttle, plane would pull hard to the right, took a lot of rudder to compensate. Very good plane........

I doubt it wing warp, considering that it flew fine before the afs was out

Austin

Where did he say that? Where did he even say it was ever flown with the AFS engaged. Jumping to conclusions here.

However, I also doubt the wing is warped. Just one possibility. Most likely out of trim. Even with the wrong engine offset it should be trimmable at some point.

As indicated aside from wing warp, the first thing you should check is the aileron's and how they both center.

Sometimes you may assume that both ailerons center the same, as they appear to do so visually, but on closer inspection you may find that the hinge line on one is higher or lower than the other.

That in turn means that when you center the aileron you may actually have one either "up" or "down" causing the roll.

Of course don't forget "P" factor either.

Fly the plane and take it high... then chop the engine completely and fly it level with the stick centered. Does it fly straight or continue to roll to one side.

If the latter check the wing warp and aileron centering.

If the former, you're just experiencing P-Factor/Torque and changing props may help a bit.

Hmm, that's weird, up until about this year, the Nextstars at my field posed no problems, flew great without the flaps and was one of my favorite trainers. Recently there seems to be a whole slew of problems of the plane going left. I wonder if the manufacturing jig is out of alignment or something?

Anyways, the last one we saw at the field, the engine was shimmed which seemed to take care of a lot of the problem but not all. Seemed to be inconsistent in its behaviour, and difficult to trim. Upon inspection of the horizontal stab, we found that it developed a bit of play both up and down, left to right (it was not glued). Owner went home to epoxy it in, which I believe will take care of the problem next time I see him.

sorry to hi-jack this thread but i have one of the first NEXSTAR made. I took to field when new excellent took it up after taping all connections in the plane to keep from coming un-hooked. He was a very excellent pilot. He took it up but could not get it to trim out. I disconnected all the AFS STUFF. Next week same problem. Took back to lhs who put it together with another excellent pilot's help. These are great people that will help anyway they can. Pulled receiver and motor from NEXSTAR and placed into V-mar HORNET. I have flew this plane for 3 yrs. no problem with trimming out. Crashed hornet first of summer ordered another trainer and was going to put motor and receiver into it. Decided to put motor and receiver back into NEXSTAR , whie looking at front of NEXSTAR I noticed the motor mount was 1/4 in over to one side of firewall. My question is this for centering the prop shaft or could this be the problem with the trimming of this plane. It is just sitting in shed to fly. Sorry about long story but would like to know whether to fly or forget.
thanks
bcb

OK, here's my opinion. Take it for what it's worth. I've been flying for about 17 years and I carry around a donated Nexstar as a club trainer. Plus I have flown several for students. The problems with the Nexstar are:

1. Too much right thrust on the engine. (As a couple guys above mentioned. Actually it's been mentioned several times before in previous threads)

2. Positive incidence on the horizontal stabilizer. (One of the other instuctors in my club noticed this just recently. I checked it with my incidence meter at home and he was right, there's about 3 degrees. (Positive incidence means the leading edge is higher than the trailing edge, making the surface rest at an 'upward angle' as compared to the wing.))

What happens (again IMO) is that as the throttle is increased at take-off, the horizontal stab makes the tail lift first, also lifting the main wheels up, and the plane starts to yaw or 'wobble' rolling primarily on the nose wheel. At the same time, the large right-thrust of the engine pulls the plane to the right. The more throttle, the more it pulls to the right. I have minimized this pull by simply NOT going to full throttle on the take-off roll, and just rolling a little longer on the runway to build up speed. And with a healthy amount of left rudder. Learned this technique by flying those dang tricky warbirds!

One of our students crashed the club's Nexstar [:@] and when I repair/rebuild it I'm going to try to put the horizontal stab at 0 degrees incidence and see how it flies then. I already have a couple washers behind the right side of the engine mount to back out the right thrust. That does help somewhat. I will report back how it flies after I try this out.[8D]

ho2zoo,

I agree with you on both points. I have a NextStar I put together for my son. I had to add 1/8" worth of washers under the right side engine mount to stop the right turn tendency.

I currently instructing a guy on a NextStar it required full up trim on the maiden. We added a bit of tail weight but the trim barely changed. I had to move the pushrod in a couple of holes for the elevator in order to get a good flair at landing, but it’s now straightened out and flies great. Its actually one of the better NextStar I've flown.\

While mine has been sitting for about 1-1/2 years I did notice that one of the wings has developed warp. I haven't incidenced it yet to see how bad it is, it is noticeable when I look at it from the leading edge.

Hogflyer

Yellerchamp,

YOU ARE THE MAN, I did exactly what you told me and the Nexstar flew perfectly for the very first time. It was just unbelievable. After the instructor took off and lever off he just held the transmitter in his hand and away it went. He could not believe that a little popsicle stick did the trick. Now I can't wait to go the field this weekend. Thanks Yellerchamp, you made me a very happy person because I really like the Nextstar. Again thanks for everything.

Cliff,

Really glad it worked out for you, happy flying