Unknown Fokker Dr1 - CG ???
03-09-2011, 04:53 PM
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Unknown Fokker Dr1 - CG ???
I have a great looking Fokker Dr1 that was scratchbuilt back in 1995. From the looks of it, the plane has never been flown. It has a ST.90 for power and is covered in what looks like SIG Coverall and handpainted "Fokker Red". I was going to put a 4 stroke on it but the firewall to front of cowl measurement is too short for any four stroke in the 1.20 range, so the ST will remain. I need to calc the CG and I know it has to be measured on the middle wing, but where? The wingspan is 58 inches and she weighs about 7 lbs. Thanks for any and all help!
Happy Flying!
Loopman
Happy Flying!
Loopman
03-09-2011, 05:38 PM
#2
RE: Unknown Fokker Dr1 - CG ???
The three wings on that plane have basically a constant chord. That means that the Mean Aerodynamic Chord is the chord of the wing. Measure the chord of each wing. For the top wing, use the widest portion including the ailerons. Measure 30% of the chord back from the leading edge of each wing. Put the CG in the middle of those three points. This will give you a stable first flight and then you can adjust it from there. Tell us how things work out. Those planes make great looking models in the air. Dan.
03-09-2011, 07:37 PM
#4
RE: Unknown Fokker Dr1 - CG ???
Check if the wings are staggered and if they have dissimilar areas, if so, things change a little.
Read these threads:
http://www.rcuniverse.com/forum/m_86...tm.htm#8686515
http://www.rcuniverse.com/forum/m_56...tm.htm#5641443
Read these threads:
http://www.rcuniverse.com/forum/m_86...tm.htm#8686515
http://www.rcuniverse.com/forum/m_56...tm.htm#5641443
03-17-2011, 03:34 AM
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RE: Unknown Fokker Dr1 - CG ???
If its any help, years ago I built a quarter scale triplane from the Bill Effinger plans and when trying to fly it it appeared very tail heavy. His plans put the CG at about one and a quarter inches aft of the lower wings leading edge. I guessed that this was too far back. I went and bought Nick Ziroli's plans for his slightly smaller DR1 just to see where he called it to balance at. Nick put the CG about a quarter inch aft of the lower wing leading edge. I rebalanced mine to that relative position and it flew much better.
