spoilers vs. ailerons

"Darrell S" wrote in news:NrVFe.51930$4o.23949@fed1read06:

Mike Rapoport wrote:
"Darrell S" wrote in message
news:BavFe.49931$4o.24620@fed1read06...
wrote:
. With a spoiler controlled aircraft, when
you stall the wings it makes the spoiler ineffective. It can no
longer spoil lift that is no longer there. --

Darrell R. Schmidt
B-58 Hustler History: http://members.cox.net/dschmidt1/
-

This isn't true. Spoilers provide effective roll control even on a
stalled wing while ailerons do not. lift does not disappear when the
wing stalls.
Mike
MU-2

Not so, Mike. Spoilers spoil lift. You can't spoil lift that ain't there
as in a stalled wing.

But is not the definition of a stalled wing one that is
producing less lift than necessary to maintain flight?

That seemed to be quite a topic not too long ago re spins.

Brian
--
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Sed quis custodiet ipsos Custodes?

"Skywise" wrote in message
...
[...]
This isn't true. Spoilers provide effective roll control even on a
stalled wing while ailerons do not. lift does not disappear when the
wing stalls.

Not so, Mike. Spoilers spoil lift. You can't spoil lift that ain't
there
as in a stalled wing.

But is not the definition of a stalled wing one that is
producing less lift than necessary to maintain flight?

Actually, the definition of a stalled wing is one that has exceeded the
critical angle of attack. The critical angle of attack is the point at
which the wing has the greatest lift coefficient.

It is true that a stalled wing still has lift, and it is also true that a
stalled wing can be provided with *some* roll control with spoilers, when in
the same situation ailerons would be useless.

I might dispute the use of the word "effective", just because often it's
used to imply some semblance of quality. But I think in this context, as
long as it's understood that "effective" simply means that the spoiler do
have an effect, there's no need for debating those semantics.

Pete

A stalled wing is still producing lift.

Mike
MU-2


"Darrell S" wrote in message
news:NrVFe.51930$4o.23949@fed1read06...
Mike Rapoport wrote:
"Darrell S" wrote in message
news:BavFe.49931$4o.24620@fed1read06...
wrote:
. With a spoiler controlled aircraft, when
you stall the wings it makes the spoiler ineffective. It can no
longer spoil lift that is no longer there. --

Darrell R. Schmidt
B-58 Hustler History: http://members.cox.net/dschmidt1/
-

This isn't true. Spoilers provide effective roll control even on a
stalled wing while ailerons do not. lift does not disappear when the
wing stalls.
Mike
MU-2

Not so, Mike. Spoilers spoil lift. You can't spoil lift that ain't there
as in a stalled wing.

--

Darrell R. Schmidt
B-58 Hustler History: http://members.cox.net/dschmidt1/
-

That's a key statement. The definition of stalled, as the FAA and the pilot
see it, is not an aerodynamic definition. It is a definition based on
aircraft
handling and controllability.

Nobody here has yet defined spoiler or aileron either. If the "spoilers" are
located far aft on the wing, and are hinged at their leading edge, would
you call them ailerons? How about if the ailerons go up only, are they
spoilers? There are plug type spoilers, hinged at the leading edge spoilers,
vented spoilers, spoilers at the front of the airfoil, spoilers at the rear
of the
airfoil, spoilers in the slot between the wing and flap and the variations
go on
and on. Their characteristics vary widely. There are lots of reports done a
long time ago by NACA on spoilers. One of the characteristics I remember
reading from these reports was the location on the airfoil was a compromise
between control response delay and control effect. Forward locations had
more effect and more delay. Aft locations went the other way. The conclusion
I came to was that the best location and size to have the good
characteristics
of ailerons was the same size and location as ailerons.

The Mead Adventure started life with spoilers, no ailerons. The Durand Mark
II
biplane had full span spoilers on the lower (forward) wing, no ailerons. The
Adventure was converted to ailerons very quickly. The spoilers were quite
unacceptable, located forward on the airfoil. The Durand biplane worked
quite
well according to Bill Durand. As I recall, they were located aft on the
airfoil, in
front of plain flaps. I once flew an R/C model specifically to test
spoilers in
combination with full span flaps. The spoilers were part of the flap gap
area, so
that the optimum lift over the flap would be destroyed with spoiler
deflection. We
started the testing by taping a spoiler to one wing of an existing
aircraft. When it
took about half aileron to fly level, we quit changing the size and
deflection of the
temporary taped-on spoiler, knowing that a wing with similarly sized
spoilers
would be controllable enough to fly (no flaps). After I completed the wing
(we used
the same aircraft that we used to test the taped-on spoilers), I estimated
that
control response should be the most similar to ailerons with the flaps down
about
10 to 20 degrees. This turned out to be right on the button. With flaps up,
the roll
rate was considerably slower than with ailerons. With flaps full down, the
roll rate
was extremely high. So much so that only a couple of landings were
attempted.
With the flaps up, roll response was just adequate both INVERTED and
upright.
Kind of neat seeing an aircraft with spoilers instead of ailerons make a
low inverted
pass. BTW, this was done around 1970. I still have the wing. Never
crashed.

My conclusion was that spoilers make good spoilers, ailerons make good
ailerons
and flaps make good flaps.


Mike Rapoport wrote in message ...
A stalled wing is still producing lift.

Mike
MU-2


"Darrell S" wrote in message
news:NrVFe.51930$4o.23949@fed1read06...
Mike Rapoport wrote:
"Darrell S" wrote in message
news:BavFe.49931$4o.24620@fed1read06...
wrote:
. With a spoiler controlled aircraft, when
you stall the wings it makes the spoiler ineffective. It can no
longer spoil lift that is no longer there. --

Darrell R. Schmidt
B-58 Hustler History: http://members.cox.net/dschmidt1/
-

This isn't true. Spoilers provide effective roll control even on a
stalled wing while ailerons do not. lift does not disappear when the
wing stalls.
Mike
MU-2

Not so, Mike. Spoilers spoil lift. You can't spoil lift that ain't
there
as in a stalled wing.

--

Darrell R. Schmidt
B-58 Hustler History: http://members.cox.net/dschmidt1/
-

Darrell S wrote:


Not so, Mike. Spoilers spoil lift. You can't spoil lift that ain't there
as in a stalled wing.


What part of "a stalled wing still generates lift" don't you understand.
A stall occurs at the critical angle of attack. This is the point where
further increase in angle of attack generates no further increase in
lift. The lift goes down, it doesn't disappear.

wrote in news:1122393811.505648.264850
@g49g2000cwa.googlegroups.com:

There are two old Senecas at my airport with the Robertson STOL mod -
full span flaps w/spoilers in place of conventional ailerons. I've seen
one of them take off with a brutally short roll, and it went up as if
on an escalator. My question is, how would one of these land in a stiff
x-wind? Is the pilot limited to crabbing approaches with a kick-out in
the flare just above the runway? Or is there no appreciable difference
with ailerons?

I'm hoping Mike R. will weigh in with his Shmoo experience. IIRC the
MU-2 has the same configuration.

Will


Why not just land across the runway.

Why not just land across the runway.

Why indeed? Just fly off a carrier... those Navy guys never have to
deal with crosswinds when flying off the boat Hmmphh... What's so
darn hard about grabbing a three-wire anyway? : )

Actually with it large vertical stabilizer and relatively small rudder, the
Helio has fairly poor crosswind performance. Most experienced Helio pilots
compensate for this by landing diagonally across the runway

Mike
MU-2


wrote in message
oups.com...
Why not just land across the runway.

Why indeed? Just fly off a carrier... those Navy guys never have to
deal with crosswinds when flying off the boat Hmmphh... What's so
darn hard about grabbing a three-wire anyway? : )