RTFM - Just make sure it's the right manual..

This was an interesting day..

After noticing a friends SU-31 collecting dust in their basement, I asked to borrow the plane for a bit. Journey home, install a receive, download the manual,setup the control throws and expo - easy breasy. However, I did have trouble setting the CG just right and needed alot of weight on the tail which caused me to add the GOPRO which set it perfect - according to the manual.

Fast forward to the field - all setup and ready to go - give it some throttle - boom - blurry video (which I fail to clean). However, that's not the worst part. Final get to take off and this is pretty uneventful, but then I get in the air - super unstable. The CG is completely wrong and the control throws are wrong (luckily not terrible wrong). OK, well I set them to spec so maybe the battery got loose or I lost the camera on takeoff.. After a few minutes I get use to the way-off-CG/control throws and pull off a rather short landing - phew - awkward phone call averted.

So, I check the CG and throws again when it dawns on me, I'm looking at an E-flight manual, but this plane is from Great Planes!

All in all, a very lucky day for me and another lesson learned - and rather cheaply (one broken prop).


Views: 468

Comment by Greg Fletcher on October 8, 2012 at 7:29pm

Didn't look like that bad of a flight. It is an aerobatic plane after all. More tail heavy means more maneuverability and less stability. More nose heavy means less maneuverability and more stability. I can prety much lool at a wing planeform and guess a cg that I would feel comfortable flying. Don't rely so much on manuals for what you learn from experience. If it doesn't look and feel right then it's probably not right. The key is experience.  

Comment by Boston UAV on October 9, 2012 at 1:46pm

I've had great success with GP manuals and recommended settings for 3D AC, less-so with some others which required individual tweaking. Being able to guess the correct CG of an air-frame is quite a unique skill you have :)

I'll update when I get the time (and weather) for another run.

Oh, and with clear video!


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