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Ribcracker
08-05-2006, 03:15 AM
I just hopped up a Cox micro warbird with a Himaxx 2015 and a 2 cell TP 480mah pack. It comes in at 6 oz. and is a speedy little devil! The cg is right exactly where recommended but the plane will not roll or invert. No outside loops either. If you give it full down elevator, it heads for the earth. I was able to roll it onto it's back a couple of times but it wouldn't hold altitude even with full down elevator.
I have my control throws maxed out. All my other 3 channel planes (e/r/t) will fly inverted but they have high wings. Even my SlowStick will roll and invert. Is this just the nature of a low-wing, rudder steered plane?

Sky Sharkster
08-06-2006, 03:58 AM
Hi Ribcracker, the COX Warbirds have a lot of dihedral, much more than scale. They appear (to me, anyway) to be designed to fly as Free Flights, with R/C added. For this reason, they won't go inverted easily.
As far as not flying well inverted, once you get it there, thank the undercambered airfoil; It generates lots of lift (as well as lots of drag) but only towards the top of the plane. Since the airfoil doesn't know any better, when you flip it inverted, it still generates lift towards the top of the plane, in other words, down! There may also be built-in decalage but I haven't looked at them closely enough to say for sure.
That said, they're great little planes, easy to upgrade and within their design and size limitations, good flyers. It would be interesting to see how a "Micro" would fly if it was designed with scale dihedral and a semi-symmetrical airfoil.
Ron

Ribcracker
08-07-2006, 02:47 AM
Thanks, Ron. That makes perfect sense. None of my other planes are configured like that so it's behavior seemed very odd to me.
It just so happens that I have an extra wing from an earlier CMW Spitfire that didn't live long enough to reveal this quirk.
I'll cut and flatten the old wing and try it (if the new Spitfire lasts long enough).
You've been helpful to me many times. I'd pat you on the back but the little sign says I'll have to spread some Rep around. We really need guys like you.
I'll let you know how the mod goes.
Peace,
Bud

Sky Sharkster
08-07-2006, 03:19 AM
Hi Bud, thanks for the kind words, I try to help where I can. It'll be interesting to see how the Spit flys with less dihedral, I've noticed the "Micros" need a lot of rudder command, and if they fly too slowly the rudder looks ineffective; I'll bet the lower dihedral will change this.
Also if you flatten the airfoil it will fly much faster at comparable throttle settings; As I mentioned the undercambered airfoil generates more drag (and lift, at low speed) than nearly any other type section. You could have a "Micro-Pylon" racer on your hands!
Good Luck!
Ron

Bill G
09-07-2006, 06:23 AM
I just hopped up a Cox micro warbird with a Himaxx 2015 and a 2 cell TP 480mah pack. It comes in at 6 oz. and is a speedy little devil! The cg is right exactly where recommended but the plane will not roll or invert. No outside loops either. If you give it full down elevator, it heads for the earth. I was able to roll it onto it's back a couple of times but it wouldn't hold altitude even with full down elevator.
I have my control throws maxed out. All my other 3 channel planes (e/r/t) will fly inverted but they have high wings. Even my SlowStick will roll and invert. Is this just the nature of a low-wing, rudder steered plane?

I thought I was the only one who ever did that! I put a 2015-4100 ran DD with GWS 5030 prop, in a FlyZone (basically pre-Cox warbirds) whey back when a mini 8 cell NiMh was the batt. Would drop out on LVC on the bench, but unloaded in the air, it wasn't a problem. Very good vertical, way too much for my skills at the time. Hell of a 45 second, seat of your pants flight!:eek:

If its undercamber, it ain't invertin' well.