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Reduce speed envelope of Great Planes RV4?

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Old 12-16-2010, 07:32 PM
Join Date: Dec 2010
Posts: 23
Default Reduce speed envelope of Great Planes RV4?

First time poster here… Thanks in advance to all responders. Sorry so long

Though I've spent many years building glow-powered planes (all quite large) this is my first electric and my first very small plane (41" wingspan). I built this from a Great Planes RV4 kit. Please see picture.

It was designed to be powered by a 280-370 brushed motor, gear-box, and ni-cads. Instead, I decided to use a Rimfire .10 brushless and 3-cell, 35amp ESC, and Lipo's because I anticipated the plane would end up being 10+ oz. heavier because I planned on beefing up the structure quite a bit (I felt the kit, as designed, would yield a very fragile airplane). This isn't what happened. Even after I added stringers b/w the main spar and leading edge, swapped out the wire gear with aluminum gear, sheeted the fore and aft top-decks, added bolt-mounting for wing, mounted servos outside of fuse, etc… The plane finished up just a few ounces more than the plans called for. Apparently, the weight saved by using the lighter brushless/ Lipo setup nearly offset all of the extra weight I added. So now, with the .10 and 11.1v, it seems that I have a plane that is way over powered. It weighs just a tad over 2lbs.

I've flown it four times now and it takes off at 1/8 throttle and climbs with full down trim at anything more than 1/2 throttle. To reduce this tendency I've reduced wing incidence to 1 degree. ..However, with a semi-symmetrical airfoil this will always be a problem if the plane is flying 4 times the speed it was intended (am I correct?).

How can I shrink the speed envelope? .I would much prefer being able to use the entire (or nearly) throw of the throttle stick. I don't have a computer radio, so end-point adjustment of the throttle is out. ..What else can I do?? ..Is there a slower prop than 10x4.5. that would work with this engine/battery combo?? ..Perhaps use just a 2-cell lipo?? I don't want this to fly like a 3D aerobat. ..I want it to fly like a Sportster or Astrohog. ..Basically, just a low-wing sunday flyer that can do loops, rolls, fly inverted, and do an occasional few seconds of knife-edge.

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