scale helis...dumb question

[david perry]

I fly a lot of fixed wing and I understand fully why a scale fixed wing
aeroplane can be harder to fly than "sports" ones, however, when it comes
to helis I don't understand why a scale Huey body on a 30 sized frame should
be harder to fly than,say, a raptor body on the same frame.

With fixed wing the wing planform can change - with a heli it's still a
disc.
With fixed wing the wing loading goes up and the stall speed rises -with a
heli surely the climb rate falls and inertia increases, but no true stall.
With fixed wing the relative sizes of the flying surfaces changes causing a
change to control and stability sensitivity - with helis the tail boom might
change I suppose, giving sharper, or slacker, yaw response, but the pitch
and roll are still controlled by the disc and that is the same.

So...what am I missing?

(Oh, and I accept that a 40lb, 5 bladed work of art will be a bit harder,
just due to (a) inertia and (b) fear)

David

[Steve Simpson]

> I fly a lot of fixed wing and I understand fully why a scale fixed wing
> aeroplane can be harder to fly than "sports" ones, however, when it comes
> to helis I don't understand why a scale Huey body on a 30 sized frame should
> be harder to fly than,say, a raptor body on the same frame.

I haven't flown scale so I do not speak from experience, but all else being equal, the effect of
adding a fuselage would come primarily from the extra weight.

Newbies are often amazed how different their .30 flies when freed of training gear.

> With fixed wing the wing loading goes up and the stall speed rises -with a
> heli surely the climb rate falls and inertia increases, but no true stall.

With helis the rotor IS the wing and is subject to similar forces. A rotor blade will stall with
too much pitch or too little airspeed, just like a fixed wing.

Note here that I said AIRspeed. A 300 mph rotor tip speed translates into very different head
speed for a .30, a .60 and a big scale ship.

> change I suppose, giving sharper, or slacker, yaw response,

I doubt that with todays super-power T/R gyros and servos, the added surface are of a scale boom
would have much of an effect, but here again, I am not speaking from actual experience.

> but the pitch and roll are still controlled by the disc and that is the same.

Except that the mass being rotated by the disk is increased by the fuselage.

On the other side of the coin, the streamlining can make for a real rocket. The fastest heli I
ever saw was a sleek white Airwolf. It was set up for nose-bleed aerobatics and was really
something to see. A myth breaker for sure!