A very basic question

"Maule Driver" wrote in message
om...
I was always under the impression that in most light a/c, the dominate
rolling effect from 'inside' rudder is the result of dihedral (or
alternatively, sweep back). RC modelers are pretty adept at setting
up
aircraft for 'pure' yaw from rudder input - no dihedral, symmetrical
layout,
etc. Or setting up aircraft to bank and turn without ailerons - lots
of
didedral.

Though I'd agree that the "forward motion of the outside wing"
explanation
accurately predicts the rolling effect from rudder input that occurs
on most
a/c - which is ok for training purposes.

I would agree with this completely. Dihedral contributes heavily to the
lateral stability of the aircraft if sideslip is present to be sure. The
prime contribution of dihedral is in the development of a stable rolling
moment with sideslip, which is consistent with what most of us are
saying.
The problem with answering many questions in aerodynamics is that there
isn't one single example or answer that will suffice.
(Lift is a PRIME example of this. ) Anyone trying to explain lift in a
simple sentence will find a slew of missing data soon to follow :-) The
problem in aerodynamics is that in much of what is happening, several
explanations are in force physically together at one instant in time.
The way we look at dihedral in the flight test community is primarily as
it's effect on the lateral stability scenario which relates with
sideslip present to relative wind, differential in angle of attack,
changes in lift raising a windward wing producing stability.
I think we're both on the same page, and dealing with the same effect
since all of what we're discussing is present in complimentary yaw IF
dihedral is present.
Now, if we inject an airplane into this equation like a Cessna 195 for
example.......... :-))))
Dudley Henriques
International Fighter Pilots Fellowship
for email; take out the trash

We are on the same page. The analogy with describing lift is spot on.

Never flown a 195 but I bet it rolls a bit with rudder too. I'd bet it has
a little to do with fuselage blanking the trailing wing lift a bit while
the leading wing works a little better. But all of that is a wild ass
guess. I'll have to ask our resident 195 guy how it responds to rudder.

Thanks.
"Dudley Henriques" wrote in message
ink.net...

"Maule Driver" wrote in message
om...
I was always under the impression that in most light a/c, the dominate
rolling effect from 'inside' rudder is the result of dihedral (or
alternatively, sweep back). RC modelers are pretty adept at setting
up
aircraft for 'pure' yaw from rudder input - no dihedral, symmetrical
layout,
etc. Or setting up aircraft to bank and turn without ailerons - lots
of
didedral.

Though I'd agree that the "forward motion of the outside wing"
explanation
accurately predicts the rolling effect from rudder input that occurs
on most
a/c - which is ok for training purposes.

I would agree with this completely. Dihedral contributes heavily to the
lateral stability of the aircraft if sideslip is present to be sure. The
prime contribution of dihedral is in the development of a stable rolling
moment with sideslip, which is consistent with what most of us are
saying.
The problem with answering many questions in aerodynamics is that there
isn't one single example or answer that will suffice.
(Lift is a PRIME example of this. ) Anyone trying to explain lift in a
simple sentence will find a slew of missing data soon to follow :-) The
problem in aerodynamics is that in much of what is happening, several
explanations are in force physically together at one instant in time.
The way we look at dihedral in the flight test community is primarily as
it's effect on the lateral stability scenario which relates with
sideslip present to relative wind, differential in angle of attack,
changes in lift raising a windward wing producing stability.
I think we're both on the same page, and dealing with the same effect
since all of what we're discussing is present in complimentary yaw IF
dihedral is present.
Now, if we inject an airplane into this equation like a Cessna 195 for
example.......... :-))))
Dudley Henriques
International Fighter Pilots Fellowship
for email; take out the trash

"Maule Driver" wrote in message
om...
We are on the same page. The analogy with describing lift is spot on.

Never flown a 195 but I bet it rolls a bit with rudder too. I'd bet
it has
a little to do with fuselage blanking the trailing wing lift a bit
while
the leading wing works a little better. But all of that is a wild ass
guess. I'll have to ask our resident 195 guy how it responds to
rudder.

I flew one years ago. Strong airplane...reminded me of something made
out of solid aluminum :-)) It flew wonderfully...extremely stable. Sort
of like a Beaver really.
As for a turn resulting from pure rudder input on these airplanes....you
still have that outside wing going faster than the inside wing
irregardless of the existence or non existence of dihedral, so it will
turn anyway eventually :-)
Dudley