Biplane C.G.
11-16-2003, 08:35 AM
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Biplane C.G.
I know this has probably been covered before but posted now and find nothing to help.Just bought a used Lazy Ace small size approx 53"wing.No idea where C.G. should be.Appeears way out of balance many Oz.on nose.Has straight wings.Thought should be at about the leading edge of the lower wing,as a general figure.Can anyone give me a quick lesson in this?Thanks
11-16-2003, 10:29 AM
#2
RE: Biplane C.G.
LE of lower wing would be too far forward.
My "Rule of thumb" for bipes is this:
Pick it up from the back-center of the top wing (inserting your fingers about half their length under the wing)
The plane should sit slightly nose down (2-4 degrees).
That will get you into a "Flyable" range. Once you have flown it, you can adjust from there.
I know it's not an exact science, but it has never failed me so far.
My "Rule of thumb" for bipes is this:
Pick it up from the back-center of the top wing (inserting your fingers about half their length under the wing)
The plane should sit slightly nose down (2-4 degrees).
That will get you into a "Flyable" range. Once you have flown it, you can adjust from there.
I know it's not an exact science, but it has never failed me so far.
11-16-2003, 10:26 PM
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RE: Biplane C.G.
Thanks for the reply Mike.You mean stand behind the plane and hold it near the center of the upper wing?Doing some radio instalation on it now tomorrow try that see ahere at ,Took 8 oz off the nose seemed awful heavy.Measured it is the 63"version.Has a MDS 68 which looks like a good piece of ballast itself.Doesn't that stand for More Dead Sticks?Never used these motors,looks like he might have stuck it in to sell the plane don't know if it needs that big an engine?Again Thanks much Bob Moodie
11-17-2003, 12:56 PM
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RE: Biplane C.G.
Since the wings are straight and both the same size, just have the CG 25 to 30 % aft of the distance between the leading edge of the most forward wing and the trailing edge of the most aft wing.
11-17-2003, 01:10 PM
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RE: Biplane C.G.
I've an interest in this as I've just (ahem) bought a Great Lakes ARC.....
Here's the version I heard: the CG should be 25% back from the front of the MAC. I applied this to a small (unknown) electric bipe and it seemed to fly ok.
Explanation: Measure the total chord from the leading edge of the leading wing to the trailing edge of the trailing wing. My bipe had straight wings with a 6" chord and a 2" stagger giving a total chord of 8". 25% of this is 2" which funnily enough is in line with the leading edge of the bottom wing..... clear as mud?
Here's the version I heard: the CG should be 25% back from the front of the MAC. I applied this to a small (unknown) electric bipe and it seemed to fly ok.
Explanation: Measure the total chord from the leading edge of the leading wing to the trailing edge of the trailing wing. My bipe had straight wings with a 6" chord and a 2" stagger giving a total chord of 8". 25% of this is 2" which funnily enough is in line with the leading edge of the bottom wing..... clear as mud?
