oxen

Concerns about my 84" span scratch built Extra 300??? It weighs about 17lbs. and the wing loading is 29oz/lb (21in center chord and 12in tip chord).
I'm using an OS 1.60 FX engine and 180oz/lb servos. Since the wings are joined together do you only use the dimensions outside of the body for wing
loading calculations? I've used the full span for wing loading. If you only use the wing area outside of the body, the loading will, of course, be greater and
quite possibly just too great??? Is attention to stall speed critical with a plane of this size or, because of the large wing area, will it tend to float a bit at
slower speeds and not just "fall from the sky"? As you can tell, I'm a novice in this area of RC - I've only flown planes with up to 60" spans and never
had much trouble with stalling. I'd certainly appreciate your comments! Many thanks, Ollie Burns

j.duncker

My Feedback: (2)

In your position I would check the CG position [ twice '] then just go fly it. I think it will be just fine.

Get it 3 mistakes high and check out the straight line stall then see if it will tip stall in nose high mush mode by wiggling the ailerons.

speedracerntrixie

My Feedback: (29)

I agree with making sure the CG is correct, however with the 1.60 this airplane will be grossly underpowere. That is a 50cc gasser airplane and the 1.60 glow engine has about the same power as a 30cc gas engine. 17 lbs is also a bit heavy for an airplane with just over 1,300 square inch wing but not too bad provided you have enough power behind it. IMO you should not even try flying it with the 1.60. I would strongly suggest you get a 50cc-55cc gasoline engine. I know this is not good news but my hope is that it will prevent you from bringing the airplane home in a bag.

oxen

Thanks to you both for your savvy comments. So far I have it 4to1 in favor of using the OS 1.60, but I am in no way
discounting SPEEDRACERNTRIXIE'S belief that this is a 50cc requirement! Where I get the 4to1 is because I posted
a similar question some time ago, and all three replies agreed that OS 1.60 would do the job. One even said that he
had hovered a 20lb. plane ( "hung it on the prop") with an OS 1.60 - wow! We'll see. I'll give it a try with the 1.60.
I know I'm throwing the dice, but the plane has been "hanging around" for some time and it won't break my heart if it
doesn't work out. I'll post the results.

oxen

I flew the plane today with the OS 160 FX and all went well! Took it pretty easy with a few fly-bys, inverts and verticals.
It handled the vertials/hammerheads quite well. Imagine a 50cc would be needed for 3D/radical maneuvers, but for just
easy sports flying the Os 160 is okay. Thanks again for your comments! Ollie B.