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Speed build Spitfire Trim Issues

Filken

Junior Member
#1
I just want to say that I love the site and the show. Great job!
So on to my question...I could use some help. I am new to flying fixed wing and absolutely fell in love with the swappable planes. I have scratch built the Flyer, Old Fogey, Baby Blender and Versa and they all fly great. The Spitfire is my first plane made from a speed build kit and I seem to have an issue with something on the airframe that causes it to roll right quite extremely. I have to set my sub trims for my ailerons to the left maximum before the plane will fly level. The ailerons have to have about 1/8th inch left pitch at center stick. I haven't had a nice calm day to test it out without wind so it's hard to tell if there is another issue, but as far as I can tell the tail and wings are straight and even. My dad and I both built a Spitfire at the same time and his flies beautifully, but mine seems to be super squirrely. I checked the CG and it is all balanced. We have identical electronics (the beef) and hardware with the exception of the battery. He has a 1300 MaH and I have a 2200 MaH. Any suggestions on what I can check would be appreciated.
 

TLMARK

Senior Member
#2
My first guess would be that you have power pod off centre or more accurately the thrust line is off?

have you got any pix?
 

xuzme720

Dedicated foam bender
Mentor
#3
I have mine on my old JR radio and I'm using the flap channel on the right aileron. I had to trim(sub trim) the flap channel separately when mine was rolling right on the maiden. It was noticeable but not extreme. Once I had it trimmed out though, there is close to 1/8th inch of up on the left aileron and about the same down on the right one. That might just be where it needs to be without adjusting thrust line...

It's pretty sensitive in pitch but my ailerons were pretty anemic. I can adjust more throw into them so they are more responsive but my guess is you are on the rear side of where the cg should be. That is where mine balanced with a 1300 all the way in the nose. It was a little squirrelly in the wind like that. I guess it's time for a bigger batt!
 
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Filken

Junior Member
#4
I have a 2200 battery and I have to move it way back as far as I can before it sticks out into the wing area. Even then it's a tad nose heavy. The CG is along the spar right?
 

Filken

Junior Member
#5
OK, so I took a good long look at the wings and it looks like the left wing is in fact warped a little. Is there any way to correct that or is it just a matter of choosing between trims or rebuilding the wing?
 

TLMARK

Senior Member
#6
I guess if you have built it with a removable wing you could try to get straight with some heat maybe a hair dryer? just be really careful as could make things much worse.

and yes the CG is the spar. And as every body could use different electrics battery placement will be different too.
 

xuzme720

Dedicated foam bender
Mentor
#7
Yes, I could stand a bigger motor on this but just slapped in one of the other power pods I had laying around, probably why it's so tail heavy for me. A few of the things to always check before flight; proper CG, controls all working in the correct directions; make sure you're on the correct model on the radio for the model you're flying. Been bitten by all of these at some point, especially when you're excited and ready to just get it in the air...
 
#8
OK, so I took a good long look at the wings and it looks like the left wing is in fact warped a little. Is there any way to correct that or is it just a matter of choosing between trims or rebuilding the wing?
I had the same problem. I ended up cutting the left-wing about 2 inches from the fuselage, being careful not to cut the servo wire, & re- glued it aligned with the right wing. Solve the problem completely. Next time I'll be more careful while assembling wing. by the way the wing was permanently mounted on the plane when I did this. Have fun ! Martin