cometravi

Hi guys,
Test flew/crashed my bipe this weekend. Its a vintage bipe called the Wizard by sterling models. WS is approx 140 cms top and 100 cms bottom. (see post 'vintage bipe'). The plans called for it to be balanced 3 1/4" behing LE of top wing which i did. Power is a 46LA turning a 10-6 APC. People who have flown this said this power plant will be plenty for this bipe. There was some play in the ailerons but very minor..

On the first take off run, it just wanted to roll over to the right, one feet off the ground.. ( there was a decent crosswind and the bipe has a dihedral so that could be the cause)

Then on the second run, there was less crosswind and it just took off, went up 10 feet or so almost vertical (There was almost no up elevator applied at this point) and wanted to hang on its prop. When it couldnt it just slipped back, and went in nose down. "Lower wing cracked in half but is easily repairable. I could feel it was very tail heavy. I tried to level it before it entered a stall but no use.. The video will be posted as soon as i can find someone with a capture card!

According to me there could be 2 possibilities:
1. CG is off
2. Downthrust is not enough

What do u guys reckon?

red91sit

My Feedback: (2)

Sounds a lot like the Multiplex Cargo, on that model it's caused by too far rearward cg.

Scalebuff

sorry for your loss m8

i had the Wizard a few years back lost it on final due to wind doctor says its common in RC pilots on landing

cometravi

Sorry to hear about that Scalebuff...How exactly did it happen?

Someone mentioned that in older models there was as lot of decalage and not enough downthrust which can cause the model to act like this. Gonna try adding more donthrust and down trim and make it nose heavy.

trroscoe

My Feedback: (39)

Sounds like your GC was to far back. Check the wing incidence in your top wing it should be negative. Measure from the bottom wing trailing edge to the top wing trailing edge. then measure the from the middle of the top wing leading edgeto the bottom wing leading edge. The leading edge measurement should be less that the trailing edge measurment if it isn't shim the trailing edge of the top wing. This will make your plane not climb as much. I had this happen on my ultimate bipe. Once I fixed the wing incedence it flew much better.

Rick