Prcedent Bi Fly 25 CG

Is this a biplane? If it is, use 25 % from the leading edge of both of the wings, then take the point halfway between the two, or more rightly, shade towards the larger wing, from halfway, a little.

Throws, if the moveable area is 25% of the horizontal, or slightly more, go

I've got one of these, but I'm not going to be able to check where the CofG should be for 24 hours or so - if you can wait that long! ;-)

Just a couple of notes about the handling for you, take 'em or leave 'em ...

Having built it with exactly what was in the box, mine came out at the top end of the weight range. If it was built true to the plan/instructions I would expect yours to be the same - mine is somewhere around 4½ lbs IIRC and it likes to be flown relatively fast. A floater it ain't! Mine is actually the second one I built (this one is about 5 years old built from a kit I bought years ago) but the weight of the first one (built 20 years or so ago) was almost identical to this one. The big difference was that I put a .28 ballraced engine in the second one whereas the first only had a .25 plain bearing on the front and that change transformed the handling of #2 compared to #1. Although it's a Bi-Fly 25 I felt that the .25 was a little lacking in grunt. The .28 has quite a bit more available and has made #2 a much nicer (exciting!) aircraft to fly. That said, you DO have to fly it all the time - and don't take your eyes off it as it will get small very quickly.

Keep the speed up on approach to land - not lifting the paint off the leading edges, but a bit faster than you think necessary. If you get too slow you will find out that it gets out of shape very quickly. Better to roll sedately off the end of the patch because you've come in a tad too fast than to watch it flick into a sickening crunch before you've even reached the mown bit.

I'll also check on what throws I've used. I'm pretty sure they're the recommended ones but they've got plenty of bite. The rudder is quite powerful so be careful on takeoff but the rudder authority in the air makes it a seriously good spinner and the flick-rolls are amazing. Inverted spins are no problem either, uphill or downhill.

Let me know how you get on with it.

Steve

I have the plans for this plane, sent to me by a guy from this group a few years ago. I haven't ever gotten around to building it yet....

The CG is 8.5 centimeters from the leading edge of the top wing.

I spent a few minutes looking at the plans again. It's amazing how small the wings of this plane are. I hope your model was built light. It looks like the kind of plane that drops like a rock when you cut the engine, if you build it too heavy.

Did you get the impression that this plane is essentially a miniature Aeromaster?

"Robert Reynolds" wrote

Just curious, but how close does that work out to my predictions?

The top wing is swept back, so I didn't feel like working out the calculations...