Skyhawk940

I have a Seagull Extra 260, 90 size. Saito 120, 16/6 prop, 8700 RPM, 9.5 lbs. The plane fly’s great, but when ever I feed in a lot of elevator the plane rolls to the right. When I do a tight loop the plane corkscrews to the right. I’ve posted here before and was advised to cut back on the elevator throws. I started with one inch up and down and now I’m at 3/4 inch each way. The manual says you can go up to 1.25 inches of throw. It’s a little better, but still does the corkscrew thing. I’ve sealed all of the hinge lines. The plane is balanced wing tip to wing tip and I’ve moved the fore/aft balance back and forth. The wings are not warped. I’ve measured everything with an incident meter. I’m at my wits end. I’m sure there are other people flying this plane. Is anyone else having this problem? And yes the elevator haves are moving together and the control rods are not flexing. The aleirons are not moving when I pull up. I’m in a VERY small club and fly by myself most of the time. I’m about ready to buy another plane!!!

blvdbuzzard

Do you have any aileron trim in? Can you trim it out with rudder or aileron? Then you know where to look for something out of line. If you do an outside loop, does it go the same way or is it the apposite roll?


Dru.

Skyhawk940

No aileron trim they are both dead even with the trailing edge (hands off flying). I' haven't tried rudder trim because the the plane flys stright and the rudder is centered. Maybe put in a little left rudder trim? The rudder is true to the center of the airframe. I've checked it.

Skyhawk

Skyhawk940

I haven't tried inverted loops as I'm not a great pilot yet and this is my first aerobat. With the way the plane snaps I'm afraid things could get out of hand quickly. I could handle this if the plane flew good.

Skyhawk

Live Wire

This may sound stupid but do you fly with your thumb or two fingers. I found my self feeding in aileron to all my control movement with my thumb. After I found out what I was doing it stops breaking to the right.

tryan02

Is the 90 split elevator? my 180 is split with 2 servos I am running a Y-harness and it took some doing to get the elevator to track equally in both directions. First I had to reverse one servo arm then adjust the pushrod length till the travel was perfect.

I was wondering if you possibly have a bad servo reverser?

Insanemoondoggie

I have the same plane ,with the same problem . Had to add 2 1/2 .ozto left wing to get it to latreral balance. Still flies like crap . Finally pulled all the gear out of it and now it`s a wall hanger..
I also have the Seagull 540 Edge .90 ,very nice plane for the money and it has none of the problems the 260 has. I weighed both wing panels and the right wing wieghs much more than the left wing.on the 260.
Good luck , I hope you find out what the problem is , and let me know lol,

darrolair

Skyhawk,
Is the horizontal stabilizer on the same paralell as the wings when viewed from the front or the rear of the airplane? Did you use an incidence meter when assembling the airplane?

Darrolair

Skyhawk940

I'm running the elevator halves on two channels with digital servos. I tried the spliter reverser and could never get it to work well. I changed over to two channels. then the analog servos would run at slightly different speeds. I changed over to digital servos before I would fly it. The digitals run at the same speed.
Insanemoondoggie, that's kinda what I wanted to hear, that somebody else is having the same type problems. I don't think it's anything I'm doing, just a not so good design. What did you replace it with?

Skyhawk

FallDownGoBoom

My Feedback: (1)

Skyhawk,

You might check to see how much right thrust is built into your engine. A couple of weekends ago I was flying my Arrow and while it flew horizontally with no problems and would roll normally, when I pulled it into the vertical it pulled to the right, and loops came out as corkscrews. Turned out that after some routine engine maintenance the week before, I'd remounted the engine and it ended up cocked off to the right. There should probably be 1 to 2* of right thrust in your motor/firewall, but more than that could cause the flight characteristics you've described.

Fred

Insanemoondoggie

SkyHawk, I had bought the seagull Edge 540 at the same time I bought the 260 and just switched the componets over to it . I did order another 260 , but after the run around I got from Horizon ,canceled the order .
With the end of flying season coming to a close ,it has been put on the wall as a wall hanger ,till building season begans. I,ll let you know what I find out then.

tryan02

Dont yell at me please!!!!

But I have 2 seagull models now and they both fly like they are on rails. It really discourages me that the 90 is so bad I considered it for a g-20 gas conversion. I hope these are a few isolated incidents. I have the edge 540 60 size saito 100 I bought used with hundreds of flights on it. But still flies great convinced me to go the next step up I bought the extra 260 180 size just slapped a Zenoah g-26 on the front never measured incidence or anything. Just did mechanical setup eyeballed surfaces measured the throws to the nerest millimeter and it required little to no trim. Both planes maneuver great and fly hands off all the way down the flight line even inverted.

So in short I feel sorry for the both of you guy's that are having those problems when I know seagull makes great models.

Enough about my good fortune I hope you can get yours figured out.

Insanemoondoggie

Thanks ryan02, I have a saito 1.00 on my 540 also and realy like this plane. I,m not putting down Seagull ,for the money ,they are a great value and will buy their products again

maddog 71

I had a edge 540 90 size It had so many problems most of them were the firewall they put lots of up thrust on it and alot of right thrust after tearing the firewall off and resetiing the engine thrust values it flew better but it still wasnt a good plane ! I think it really depends on which day it was built on . We have a guy in oour club that had the yak 50 size all of its problems layed in the balance seagull had the wrong CG other then that it flew pretty decent!

Skyhawk940

Interesting point about engine offset. I mounted the engine with the supplyed mount and never measured. I thought the offset would be built into the firewall. If there is any right offset, it isn't as much as most of my other planes. Wouldn't more right thrust make things worse?? I have to feed in a little right rudder to keep it stright on takeoffs as it is.

Skyhawk
Sandusky, OH

tryan02

I am not sure but doesn't most the yaks just a rule of thumb measure CG from against the fuselage instead of wingtips? Due to the kind of slant-back wings?

And BTW for the record I had to add a whopping 10.5 oz to the tail on my 180 to balance the g-26 and when I measured from prop tip to the tip of the horizontal stab on both sides I had a little less than 1/16" difference. So I assumed it was 0º thrust left or right.

FallDownGoBoom

My Feedback: (1)

I'd agree that most planes have their offset thrust angles built into the firewall, and we never think about them. But since you'd already checked everything else that would cause it to veer to the right/corkscrew, it was something to at least consider. Are all the wing dimensions equal on both sides of the plane? Stab tip to wing tip distance the same on both sides, stab parallel to wing, stab and wing square to the fuselage?

The only other thing I can think of is that when you're flying and pull up elevator, one side of the elevator flexs more than the other due to the air pressure change. Could one of the elevator pushrods be bending more than the other under stress?

k3 valley flyer

My Feedback: (18)

I have the Seagull 260 with an OS 75 and none of these problems. You stated in post one this happnes when a lot of elevator is fed in, are you describing a snap? Most aerobatic planes will snap with extreme up elevator and speed, usually adjust my dual rates so it can't snap on low rate and stay aware of it on high rate. Also, try adjusting the CG to see if that helps. Sorry for your bad luck with the 260, love mine.

charlie1960

the snap he describes is a high speed stall.
my plane, a seagull extra300 in.75 size does it too if i give it extreme elevator input at a moderate to high speed.
lower you rates some more. the plane will still make reasonably tight loops. without falling off to one side.
i have my elevators set about one half inch from centered. thats all it needs.

the wing on this plane is thin. when you change the angle of attack abrupty, as in feeding in a lot of elevator you disrupt airflow over the wing. like a boat paddled turned sideways in the water. it WILL stall the wing.
as far as the way the plane flies..its one of my favorite planes

super tigre 90 14x4 wide APC

Skyhawk940

I'm begining to think it's snaping like you discribed. I start a loop and around the top I tighten it up with more elevator and then it happens! Everyone says too fast + too much elevator = high speed stall. Would maybe a 16x4 (16x6 now) prop be better to slow things down some??? I moved the CG forward a bit, but it's crappy weather this weekend.

Skyhawk

tryan02

I'll be dipped!!!!!!!! I jinxed myself.

Today I was ringing my 260 180 size with a zenoah g26 out quite a bit tached it and it was turning a 16 x 8 at 4400rpm. I usually try to manage my throttle through maneuvers but today I said let her eat.[X(]

Well I was doing some split S turns I turned inverted full throttle yanked back on the stick it snapped to the right in the bottom of the loop did it a few times on me but as I remembered this post I thought ease up on the throttle and sure enough split S turns with no snap to the right. Gotta get her back in the air to make sure thats really what was going on.

charlie1960

a 16x4 will help slow your speed down
but its more the angle of attack on the airfoil than speed.
reduce the elevator throw.

charlie1960

the reduced pitch on the prop will also bring the max rpms up.

tryan02

Thanks I'll stick with the 16 x 8 its reccomended by the manufacturer and my motor is still breaking in and getting faster. I'll just remember not to feed the full 3/4" elevator throw I was trying to throw it around like I do my parkzone t-28 well I learned that a 1/4 scale gasser doesnt fly like a foamie.

jaka

Hi!
Any plane that snaps in either a sharp turn or in a loop...is to heavy!
Or more precisely has too high wing loading!!