How come the wings bank when I use the rudder

Dudley Henriques wrote in
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Bertie the Bunyip wrote:
Dudley Henriques wrote in
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Bertie the Bunyip wrote:
Dudley Henriques wrote in
:

Bertie the Bunyip wrote:
Dudley Henriques wrote in
:

Bertie the Bunyip wrote:
Dudley Henriques wrote in
:

Bertie the Bunyip wrote:
Dudley Henriques wrote in
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Bertie the Bunyip wrote:
Dudley Henriques wrote in
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:

Bertie the Bunyip wrote:

OK, I think I have it. There're (roughly) similar
problems
with
the
transonic stuff I fly but for some different reasons.
Surely
there
are some buffet isssues with the ailerons at large
displacements
as
well?




Bertie
I've not noticed aileron buffet in the 38 even at max
deflection. The ailerons are extremely effective on the
airplane. About buffet; you actually work high performance
jets
like the 38
by
using the buffet boundary. You can pull the pole and feel
the
buffet
onset in pitch. It's a highly effective warning when
maneuvering
hard.

you're talking mach buffet now, right? not normal flow
seperation..

I would have thought you might get buffet problems with
large
deflections in and around transonic flight. We can,
certainly,
but our airplanes aren't desingned for supersonic flight,
of
course..

bertie
The buffet limit is actually the subsonic buffet limit and
defines
the
lift limit line for the 38. In other words, below corner
speed,
you are aerodynamically limited in maneuvering room by the
lift
limit
line
which basically means you can pull to the buffet.
In effect, the tactical buffet line defines the left side of
the
T38's
flight envelope.
Yeh, OK I understand buffet in relation to loading but the
control
deflections have no effect on the onset of buffet? Is that
not
why
you
have a limit when close to mach 1?

Bertie

The roll restriction is totally unrelated to tac buffet. For
all
practical purposes you can forget aileron buffet as a problem
in
the
T38. The issue with the roll limit is divergence through
inertia
roll coupling. In other words, at the q found at .9 Mach and
above,
max aileron throw will generate a roll rate high enough that
the
roll axis changes from pure roll and couples either in pitch
or
with
yaw or even both under specific angles of attack as the roll
is
initiated; and
this
NEW roll axis is so unstable due to the IYMP that departure is
a
real possibility.

OK, which is what you posted originally before I went off on a
tangent! I suppose I was thinking that the divergence was
started
off
by a mach buffet triggered by the ailerons, but I'm with you
now.
I
think..


Bertie
We'll have you checked out in the 38 in no time :-))

Heh he, 'Who'd pay for the gas?


Bertie
That's the secret. The only guy I know who can afford to fly these
things without actually getting paid to fly them is Ross Perot
Jr.,
and
even he's in a world of trouble with his T38. He's caught between
the
government and his lawyers. I can't think of a worse place to be
than
that :-))


Yeah. I have an offer to fly in an old jet fighter. I only have to
put
gas in it and that comes to nearly a grand for an hour!


Still, I think I'll do it. Al I have to do is find a window when he
actually has it running!


Bertie
Sounds like fun. What is it?


Vampire.


I think you'll be surprised at how easy it is to fly.


According to the owner, it's a piece of cake.

About like a high perforamnce single, but with very short endurance.

Contrary to
popular belief, I've always felt that the faster they fly the easier
they are to fly. You can do practically everything you need to do in
the
T38 for example with your feet flat on the floor. Practically no
adverse
yaw at all. It's a dream to fly.
Good luck with your flight.
D

Thnaks! Won't be anytime soon. I think they broke it again.


Bertie

Vampire? The side by side version I presume?
Remember that great scene in "Breaking The Sound Barrier" when the
"hero" takes his wife on a trip from England to Egypt in a two seat
Vamp? Beautiful black and white photography in that picture.


I do actually. I love the way they make it look like they did it
first...




Hope you get to fly it. Nearest thing I can relate to that I've flown
would be the Canadair Tutor. I flew the Snowbirds #10 as a guest of
the
team at one time. Great little airplane and very easy to fly.
I'm sure you won't have the slightest problem with the Vampire if they
ever get it running.
D


Oh it's often running, then its broken, then it's running, then it's
broken! The lost the canopy on it once and it cost more to replace than
it hadcost to buy the airplane!


I have a pic of the snowbirds in Sept Isle Quebec I took in 1979, I
think. They had just flown through Mt St Helen's plume and damaged their
airplanes! I didn;t get up close to them, but I was up in the tower and
the controllers told me their windscreens had been badly frosted by the
incident. I'll have a rumage around for it.


Bertie

wrote in news:1193070733.442941.237020
@v23g2000prn.googlegroups.com:

On Oct 21, 3:56 am, Bertie the Bunyip wrote:
wrote in news:1192935582.999886.201640
@t8g2000prg.googlegroups.com:



In addition to what others have said, another interesting question
to
ponder is why the airplane yaws when you bank.

The yaw is induced by the ailerons, so the only time you need to
apply
rudder is when you are changing your bank angle with the ailerons.
On
the side where the aileron is down, the wing has more lift, and
more
drag. On the other side, the lift is spoiled and there is less
drag.
The draggy wing yaws backwards, requiring opposite rudder.

that's adverse yaw. I beleive he meant why does the airplane yaw in
the
same direction (eventually) as the direction of roll?

Bertie



- Hide quoted text -

- Show quoted text -

Bertie,

I assumed that adverse yaw was what he was asking about since it is
the most pronounced effect.

To answer the question the other way:

The reason for rudder use in a sustained bank is due to the fact that
the airspeed of the outside wing is slightly higher than the airspeed
of the inside wing due to the difference in arc-distance that each
wing is traveling in a turn. The outside wing has a little more drag
due to the higher airspeed and a little bit of rudder is required to
compensate.



Ooops!

I don't think that is what he was asking either! Though both statements
you made are correct.

I think he was asking why, when you bank, the airplane also (eventually)
yaws in the same direction.
Simply put, if you bank without yaw, you slip (after the adverse yaw
thing settles down a bit) and that slip will apply a force to the fin,
coarsely dragging the nose into roughly the direction the airplane is
going.
But, as this poster points out, adverse yaw will cause it to initially
yaw in the opposite direction due to adverse yaw, and then rudder will
be required to ensure the yaw is tangential to the line of flight.
IOW the fin will knock the airplane in roughly the right direction but
you need to use your feet.


Bertie

Bertie the Bunyip wrote:

Bertie
Vampire? The side by side version I presume?
Remember that great scene in "Breaking The Sound Barrier" when the
"hero" takes his wife on a trip from England to Egypt in a two seat
Vamp? Beautiful black and white photography in that picture.


I do actually. I love the way they make it look like they did it
first...

Yeah, Yeager was good at that too. I've yet to hear him give George
Welch the credit he has always been due for being the first through mach
1.......but I have to admit, the Brits made some great movies about
early aviation. The old B&W's were the best I think. The films they did
on Bader and Guy Gibson were superb movies. Leslie Howard doing Mitchell
might have been a bit melodramatic I think :-))




Hope you get to fly it. Nearest thing I can relate to that I've flown
would be the Canadair Tutor. I flew the Snowbirds #10 as a guest of
the
team at one time. Great little airplane and very easy to fly.
I'm sure you won't have the slightest problem with the Vampire if they
ever get it running.
D


Oh it's often running, then its broken, then it's running, then it's
broken! The lost the canopy on it once and it cost more to replace than
it hadcost to buy the airplane!

I'd say the trick here is to make damn sure it's on the "running" side
of that sin curve the day you get to fly it :-))


I have a pic of the snowbirds in Sept Isle Quebec I took in 1979, I
think. They had just flown through Mt St Helen's plume and damaged their
airplanes! I didn;t get up close to them, but I was up in the tower and
the controllers told me their windscreens had been badly frosted by the
incident. I'll have a rumage around for it.

I never knew that, but it would make sense. The grit in the air would
have been quite dense. I once dove a Mustang through a rain shower and
damn near stripped the paint right off it. My crew wanted to kill me
:-)


Bertie



--
Dudley Henriques

Dudley Henriques wrote in
:

Bertie the Bunyip wrote:

Bertie
Vampire? The side by side version I presume?
Remember that great scene in "Breaking The Sound Barrier" when the
"hero" takes his wife on a trip from England to Egypt in a two seat
Vamp? Beautiful black and white photography in that picture.


I do actually. I love the way they make it look like they did it
first...

Yeah, Yeager was good at that too. I've yet to hear him give George
Welch the credit he has always been due for being the first through
mach 1.......but I have to admit, the Brits made some great movies
about early aviation. The old B&W's were the best I think. The films
they did on Bader and Guy Gibson were superb movies. Leslie Howard
doing Mitchell might have been a bit melodramatic I think :-))

Yes, they did do some good ones. as good as any done elsewhere.





Hope you get to fly it. Nearest thing I can relate to that I've
flown would be the Canadair Tutor. I flew the Snowbirds #10 as a
guest of
the
team at one time. Great little airplane and very easy to fly.
I'm sure you won't have the slightest problem with the Vampire if
they ever get it running.
D


Oh it's often running, then its broken, then it's running, then it's
broken! The lost the canopy on it once and it cost more to replace
than it hadcost to buy the airplane!

I'd say the trick here is to make damn sure it's on the "running" side
of that sin curve the day you get to fly it :-))


Oh they keep it well. It's just the nature of the beast, isn't it?


I have a pic of the snowbirds in Sept Isle Quebec I took in 1979, I
think. They had just flown through Mt St Helen's plume and damaged
their airplanes! I didn;t get up close to them, but I was up in the
tower and the controllers told me their windscreens had been badly
frosted by the incident. I'll have a rumage around for it.

I never knew that, but it would make sense. The grit in the air would
have been quite dense. I once dove a Mustang through a rain shower and
damn near stripped the paint right off it. My crew wanted to kill me
:-)


Yeah, i've takne the paint off in rain lots of times.

Went through hail once. We cracked the outer panes of several screens,
took every single antenna and lamp off the airplane, holed the radome in
many places and trached on fan blade.

The noise of it was unholy. It sounded like a freight train. Crew comms
were impossible. It lasted about a minute, maybe a bit more. Not nice
but we survived it anyway. Ancient old radar wasn't worth the space it
took up.


bertie

Bertie the Bunyip wrote:
Dudley Henriques wrote in


Oh they keep it well. It's just the nature of the beast, isn't it?

Those old birds can be cantankerous to a fair thee well can't they :-))

Yeah, i've takne the paint off in rain lots of times.

Went through hail once. We cracked the outer panes of several screens,
took every single antenna and lamp off the airplane, holed the radome in
many places and trached on fan blade.

The noise of it was unholy. It sounded like a freight train. Crew comms
were impossible. It lasted about a minute, maybe a bit more. Not nice
but we survived it anyway. Ancient old radar wasn't worth the space it
took up.


bertie

Well....what would flying be like without a little "fun" once in a while
huh?? :-))))))


--
Dudley Henriques

Dudley Henriques wrote in
:

Bertie the Bunyip wrote:
Dudley Henriques wrote in


Oh they keep it well. It's just the nature of the beast, isn't it?

Those old birds can be cantankerous to a fair thee well can't they

Well, ikinda like 'em like that myself!

:-))

Yeah, i've takne the paint off in rain lots of times.

Went through hail once. We cracked the outer panes of several
screens, took every single antenna and lamp off the airplane, holed
the radome in many places and trached on fan blade.

The noise of it was unholy. It sounded like a freight train. Crew
comms were impossible. It lasted about a minute, maybe a bit more.
Not nice but we survived it anyway. Ancient old radar wasn't worth
the space it took up.


bertie

Well....what would flying be like without a little "fun" once in a
while huh?? :-))))))

Ech, kinda past that nowadays!
That was some time ago and I haven't flown with such a poor radar in a
looong time.


Bertie

Bertie the Bunyip wrote:
Actually, are you sure the 195 is zero dihedral? Most high wing
airplanes that have zero dihedral look like they have anhedral. (Swick
T-cart, f'rinstance)
It's tapered as well. so even zero dihedral on top would still give some
below!

He's right, Bertie. Zero. Here's a copy of an old Cessna brochure which
states so explicitly:

http://cessna195.org/classic/brochur...chure=7&page=2

On Sat, 20 Oct 2007 22:13:36 -0700, "BT" wrote:

Isn't interesting that entry level RC Aircraft only have rudder and elevator
controls.. and then turn just fine.
Funny that a full sized airplane would react the same way.

Yes, but you're not sitting *in* the R/C model, so you don't realize
that it's slipping and skidding all over the sky. Wouldn't be so
comfortable in a real airplane... though many of the older low end
ultralights had only rudder, no ailerons, either.

A high wing plane gets some dihedral effect from the wing position,
even if the actual geometric dihedral is zero. Sweep also acts as
dihedral, too.

OTOH, my Kolb has zero dihedral... and the rudder has just about nil
roll effect.

-Dana
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Rich Ahrens wrote in
ouse.com:

Bertie the Bunyip wrote:
Actually, are you sure the 195 is zero dihedral? Most high wing
airplanes that have zero dihedral look like they have anhedral.
(Swick T-cart, f'rinstance)
It's tapered as well. so even zero dihedral on top would still give
some below!

He's right, Bertie. Zero. Here's a copy of an old Cessna brochure
which states so explicitly:

http://cessna195.org/classic/brochur...chure=7&page=2


Yeah, zero in the top, but since it's tapered, there can't be zero on the
bottom...


Bertie

On Oct 21, 7:13 am, "BT" wrote:
Isn't interesting that entry level RC Aircraft only have rudder and elevator
controls.. and then turn just fine.
Funny that a full sized airplane would react the same way.

In a stall, you pick up the low wing with rudder, not aileron, that only
adds adverse yaw, more drag on the low wing, and fights the rudder.
BT

Using aileron to try to raise a dropping wing in a stall
increases the AOA on that wing and can aggravate the drop, causing a
spin. That's the real reason for using rudder.
The roll couple when we add rudder has a lot to do with
wingtip vortices. The vortex costs some lift as the air flows off the
bottom of the wing and over the tip. Sticking a wing ahead interferes
with that and can improve the lift on that side.

Dan (currently in Africa, where I find the Internet alive and
well)