Wright Stuff C

[lechassin]

sigh...

Why is it always the Wright Stuff forum that gets heavily spammed?

Are you referring to off-topic banter? If so, apologies

[CrayolaCrayon]

sigh...

Why is it always the Wright Stuff forum that gets heavily spammed?

Are you referring to off-topic banter? If so, apologies

He's talking about the 20 Russian threads that popped up this morning.

[lechassin]

Oh, OK.

On-topic: I'm seeing references here and there to CGs some distance behind the center of the wing, so >50% chord from the leading edge. Is this working for people,, and if so, how??? If we try to go anything much past 24mm (30%) we have to reduce decalage to zero and the plane drags its a$$ around really low. If we were to go even further back we would need negative decalage, to hold the tail up. In any of those cases the plane is grossly unstable.

What's the consensus?

[coachchuckaahs]

Oh, OK.

On-topic: I'm seeing references here and there to CGs some distance behind the center of the wing, so >50% chord from the leading edge. Is this working for people,, and if so, how??? If we try to go anything much past 24mm (30%) we have to reduce decalage to zero and the plane drags its a$$ around really low. If we were to go even further back we would need negative decalage, to hold the tail up. In any of those cases the plane is grossly unstable.

What's the consensus?

With or without rubber? It will also depend on tail moment. With rubber, ours is around 60% I believe, and 5mm decalage.

Coach Chuck

[Lorant]

I think people more often refer to the CG being some distance behind the front wing post or ahead of the rear wing post, not the center of the wing. However, I have observed many FF kit planes fly with very low decalage. I highly doubt that anyone has the center of their wing behind the CG, because the most common pitfall of FF kit flying people is roll stability, rather than pitch stability.

[jinhusong]

Our biplane, CG is 3.2cm from LE, ahead of center of wing.

Monoplane, CG is 4.2cm from LE, it is after the center of wing.

Aerodynamic Center (AC) for light wing is at 1/4 of the chord, not center of the chord.

[lechassin]

We keep our CG at the center point between the hooks, so that we can use any motor without retrimming the plane.

It looks like the monoplanes tolerate a more aft CG, and even the pipes in here have a CG more aft than us. We have the longest tail I've seen, a CG more forward than any of you, and our recoveries are good but not great. Are you folks able to get decent recoveries with the CGs so far back?

[CrayolaCrayon]

You really shouldn't be trying to hit the ceiling in the first place

[lechassin]

Because our recoveries are only adequate, we do avoid obstacles at all cost. The problem we have is HVAC, flying right under a vent can be worse than a touch.

It sounds like some of you in better climates don't need to deal with that.

[coachchuckaahs]

We touched on both flights at State. Lost 5 feet or so on a hard touch, 2-3 feet on a soft touch.

Coach Chuck