Boilermaker1

My Feedback: (1)

After a long dismal winter in Indiana, and a weird work schedule, I finally flew by GWS TM400 yesterday. After a hand launch, it went to climb straight up and stalled and.....bam. Only cracked the motor mount though.
After evaluation, I think my CG is to far aft. It seems pretty tail heavy. I'm using the stock motor and 7cell 1100 NiMh batt.
A/c with battery weighs in at 21.2 oz. I've added 2.9oz of wt in the nose and it is still tail heavy. My CG (with ballast) is about 20mm aft of lower wing LE. The book says it should be 10mm aft.
After reading other TM400 posts including Greg Covey's, it seems like mine is heavy. I did paint the fuse. I don't think that made that much difference.
Am I doing something wrong? Should I keep adding more weight to the nose?

Thanks for any help,
Phil

Jagzilla

Try hollowing out your battery compartment so you can slide the battery all the way forward to just behind the motor. I have mine balanced at about 8-10mm back from leading edge of lower wing. 2.9 oz's is a lot of lead, you need to rearrange the battery/electonics to loose some of that. I still added about a 1/3 oz of lead to mine in the front to get it to balance. Overall, at 21 oz'as weight, I don't think your bird is overly heavy. I'm not sure about your batteries though, as I only use lipos for mine. I don't even know how those batteries look to know if you can slide them up more forward. If you can, get a 3 cell lipo for it, It makes a big difference! The bird is a great flyer once you get those sorta issues sorted out. I love mine, and really enjoy flying it.
J

hargravebl

I got to agree with the Jag-meister on this one, I use a GWS 9.6v 730aMh bat and I didn't have to hollow the battery compartment out...mine balances between 0-10mm off the leading edge. But with the battery you are using you just might have to hollow it out.

Just another note from my experience...are you balancing the plane upside down or right side up? You can get a false reading right side up...and it will seem tail heavy...so even though it is a bi-plane balance from the lower wing upside down.

Jagzilla

Actually, I balance my plane right side up, and it seems to work fine. I know that low wing airplanes are to be balanced upside down, but that is news to me that biplanes are. I'd check into that.
J

hargravebl

Well see that's the thing Jag, I know for sure that low-wing planes need balanced upside down but I've never really heard anything about bipes...I've just been going off my own experiences. I had big problems balancing my TM400 right-side-up but upside down she balanced perfect. Don't want to give anyone bad advice if someone else knows more than I do.

Anyone else out there have opions on balancing bipes?

Boilermaker1

My Feedback: (1)

SUCCESSFULL FLIGHT! Thanks for all the help guys!
I balanced it right side up. Added about 2.5oz of weight in the nose AND made sure the batt was full fwd. (still seems like a lot of wt)
I had never heard of balancing an a/c upside down. I work on L1011's, B757's and B737's and I've NEVER seen one on it's back for weight and balance! Just kidding.
Anyway, it flew great! I think part of my problem was I wasn't used to an electric airplane with this kind of power. I have the little TM and it can't climb out of it's own shadow. The TM400 wan't to climb straight up, so right after the hand lauch, I just reduced pwr a bit and off she went! Flys great, easy to handle.

Thanks again for the help,
Phil

hargravebl

Glad to hear that you got the balance worked out, the TM 400 sure is a sweet flier when you get the kinks worked out.

Yeah a weight and balance on REAL planes is a whole different thing, I work on Navy planes. [8D] (Top Gun glasses)