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Old 07-06-2009 | 04:51 PM
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exciter900rr
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From: Cathedral City, CA
Default RE: Nitro models pusher Bobcat?

ORIGINAL: azrcaddict

Hey guys...I pickd up a Bobcat used with no paperwork. Anybody know where the c/g is?? It has an OS .61 on it now. tried take off yesterday, a little trouble weith steering. Also seemed to take a LOT of speed to lift. Never left ground because of steering trouble.
The manual says, "10 1/2" from the LE of the wing at the fuselage" I have mine in between 10 1/4" and 10 1/2" for the leading edge @ the fuselage, and it seems to fly fine.
HeliTB has it right to make the elevator flat with the top of the stab- I'll go out to the garage in a bit and measure it so it will be a no brainer for you.
Also, some have recommended that there be a "positive angle of attack" when the airplane is at rest on the wheels, but I don't recall anyone giving an actual number per se.
what I have experienced, is that the plane will lift off like a trainer like this- BUTTER as they say- smooth and silky, all by itself.... BUT too much, and your first landing will be absolutely unforgettable, ( bounce- bounce, bounce- etc....(My bouncy maiden [link]http://cvrcclubvideos.us/HDVids/KenBobcatMaiden.wmv[/link] )with a loud crunch at the end. )as many in this thread have also noted. I would advise (at a C/G of 10 3/8" back from the LE @ the fuselage/wing intersection) ** I hate having to clarify, but this has proven to work well with me**
To set your angle of attack at between 1/4" to 1/2" positive. measure this by setting the plane on the ground, gear down, and measure from the trailing edge net to the fuselage, and then measure the center of the leading edge radius at the fuselage. for example, your trailing measurement is 6 1/8", then hopefully your leading measurement should be in the neighborhood of 6 3/8" to 6 5/8". this will give you a slightly positive angle of attack, and will let you climb out nicely with a little up elevator. **just a little bit, AT SPEED**

Now for the fun part... LANDING
I would just get a NICE RELIABLE LOW Idle set on your engine, and use it on your final approach- I have become accustomed with really flaring the elevator on this bird, and it has proven to give really nice landings with it once I got used to it. you just want to get into a nose high attitude, and keeping the nose up you can adjust your decent with little blips of throttle as necessary.
If the plane comes in too fast, it'll bounce, and with this plane it seems to bounce progressively higher each time, while the airspeed keeps bleeding off... And you know that aint no good!
Good luck with things, and if there are any more Q's, post'em! there's a ton of people in this thread who love to chime in and give advice!

P.s. there is a vid one page back of our club videographer shooting touch and goes- if you watch it, it will give you a feel for approx how it likes to come in.
KM