How are joysticks 'powered' in gliders?

Just to return to your original question, what caused you to suspect
that gliders needed power assisted controls ?
AFAIK, there is no power assistance in the common Cessna and Piper GA
aircraft, unless you are using the autopilot. Am I wrong in this
assumption ?

No, you are not. rudder, ailerons, and elevators are direct cabled with
no power assist. Cessna (from the early '60s on) uses an electric motor
for the flaps but even this was un-necessary, IMHO, for the 182 and below.

Tony V.

John Giddy wrote:


Just to return to your original question, what caused you to suspect
that gliders needed power assisted controls ?
AFAIK, there is no power assistance in the common Cessna and Piper GA
aircraft, unless you are using the autopilot. Am I wrong in this
assumption ?


It seemed to me that if there was enough mechanical advantage in
a joystick, no one would ever have bothered to design with a
full-length control stick. The latter takes up more space and
weighs more.

--

FF

On 27 Feb 2005 18:51:37 -0800, wrote:

John Giddy wrote:


Just to return to your original question, what caused you to suspect
that gliders needed power assisted controls ?
AFAIK, there is no power assistance in the common Cessna and Piper GA
aircraft, unless you are using the autopilot. Am I wrong in this
assumption ?


It seemed to me that if there was enough mechanical advantage in
a joystick, no one would ever have bothered to design with a
full-length control stick. The latter takes up more space and
weighs more.

I get the impression that there is a semantic problem here. If by
"joystick" you mean something like the toy used with a PC for a flight
simulator, I might be able to see your problem. However, in my
experience in the gliding movement, "joystick" means any control which
operates the control surfaces, and doesn't have a rotary wheel or
"yoke". The length of a joystick can be anything from about 9 inches
to a couple of feet, depending on the glider, so there is ample
capacity to arrange suitable mechanical advantage if needed.
I see you are going to take up the suggestion to visit a glider field
and have a trial flight. This will clarify your understanding better
than long rambling text like this :-)
Cheers, John G.

Actually Fred, your question is interesting to us at Freedoms Wings Canada
www.freedomswings.ca, where we are indeed looking to design a glider control
system utilizing a 'joystick' to control servos (from autopilots) driving
the control surfaces. This would enable a larger population of pilots with
disabilities to fly, providing control to paraplegics and some higher
functioning quadriplegics who have limited strength in their arms and
wrists.

We also envision a second phase where we will supplement the foregoing with
a microelectric gyro for yaw control, and thereby enable a 'sip 'n puff'
control for the glider in flight. A Professor of biomedical engineering at
the University of Toronto, and the folks at Barry Aviation
www.barryaviation.com, believe this can be done, even with a limited budget.

I can't begin to describe how exciting this would be for someone who can at
present drive only a sip 'n puff wheelchair.


wrote in message
oups.com...

I note that some gliders are controlle with a joystick which
makes me curious as to how the control surfaces are powered.

Assuming these are useable by people who lack the forearms of
a truck driver, how are they powered?

Do these systems use electric servos with a battery recharged
on the ground? Do they use vaccumm assist from a venturi?

Just asking?

--

FF

To add to Bill's explanation, control rods through
belcranks is the simplest. Some older gliders used
cables and pulleys. Some early glass gliders used complex
gearboxes to convert linear into rotary movement and
modern gliders with flaperons have mixer arrangements.
All have one thing in common they are directly mechanical.
In most modern gliders the stick forces are very light,
frightening so in something like a Discus. Some of
the older gliders did get heavy at speed, for instance
at 80kts the ailerons on a Sedbergh (Slingsby T21)
are set in concrete requiring two hands or even four
if available, not to mention the foot behind the stick
to relieve the need for forward pressure on the stick.

DJ

At 15:30 25 February 2005, Bill Daniels wrote:

wrote in message
roups.com...

I note that some gliders are controlle with a joystick
which
makes me curious as to how the control surfaces are
powered.

Assuming these are useable by people who lack the
forearms of
a truck driver, how are they powered?

Do these systems use electric servos with a battery
recharged
on the ground? Do they use vaccumm assist from a
venturi?

Just asking?

--

FF


You really need to visit the nearest gliderport and
take a ride. Assuming
you are in the USA, check www.ssa.org and click the
button 'Where to fly' to
find the nearest location.

One of the great beauties of gliders is their simplicity.
Usually, the only
'power' in the glider is a small battery to power the
radio and a few
instruments. Everything else is powered by the pilot.

The control forces in modern gliders are small enough
that pilots can fly
with their finger tips most of the time. If you see
a glider pilot with
'truck driver forearms', it's from assembling the glider,
not flying it.

Bill Daniels

Don Johnstone wrote:
...
In most modern gliders the stick forces are very light,
frightening so in something like a Discus. Some of
the older gliders did get heavy at speed, for instance
at 80kts the ailerons on a Sedbergh (Slingsby T21)
are set in concrete requiring two hands or even four
if available, not to mention the foot behind the stick
to relieve the need for forward pressure on the stick.


What is it that causes the difference between the two?

--

FF

wrote:


Don Johnstone wrote:
...
In most modern gliders the stick forces are very light,
frightening so in something like a Discus. Some of
the older gliders did get heavy at speed, for instance
at 80kts the ailerons on a Sedbergh (Slingsby T21)
are set in concrete requiring two hands or even four
if available, not to mention the foot behind the stick
to relieve the need for forward pressure on the stick.


What is it that causes the difference between the two?
Simply said: advances in aerodynamic design. The complex answer is too
complex for me to anser well :-)

André

Actually, It's an interesting question. Some gliders have very short
sticks and light control forces (almost any current racing glider comes
to mind), while some have long sticks and heavier forces (Blaniks,
Larks, and 2-33s come to mind).

There have been gliders with small sidesticks (original Zuni, HP-18,
Monerai) but sidesticks have not really caught on - probably because
they make it really hard to fly left (or both) handed - which can be
useful during some cockpit chores.

The problem with a real short sidestick is the motion becomes a bit
awkward, especially in pitch, while with a longer stick the arm can be
rested on the pilot's leg and precise control is easy.

I think non-flyers may think aircraft need powered controls just as
cars need power steering and brakes, forgetting that cars used to be
available without either (VW Beetle, anyone?).

And surprisingly large aircraft fly perfectly well with manual controls
(albeit usually with wheels and lots of control motion, and often the
rudder is boosted) - For example, Boeing 707s (I've flown the KC-135
and it is surprisingly easy to maneuver), all WW2 bombers, even the
Spruce Goose, I believe.

Control wheels in small airplanes are abominations, mainly there to
make the spamcan seem either like a car (Arrgh!) or a DC-3. How manly.
Note that the new crop of lightplanes have more sticks in them -
including sidesticks, which open up the cockpit a lot. Also, the trend
in large military (B-1, C-17) and commercial fly-by-wire planes is also
to sticks, since the leverage provided by a wheel is no longer
required. Boeing is an exception in it's commercial designs - the 777
could have used a stick. It will be interesting to see if the 787
keeps a wheel, now that the B-1 and C-17 are Boeing planes.

Lots of neat technology (and some magic) involved in the design of
aircraft flight controls - especially ailerons.

Kirk

wrote:

There have been gliders with small sidesticks (original Zuni, HP-18,
Monerai) but sidesticks have not really caught on - probably because
they make it really hard to fly left (or both) handed - which can be
useful during some cockpit chores.
Note that some newer designs do feature sidesticks though, the Diana 2 being
one of them. It's not a dead concept.

The problem with a real short sidestick is the motion becomes a bit
awkward, especially in pitch, while with a longer stick the arm can be
rested on the pilot's leg and precise control is easy.
I have never flown one, but can't you rest your hand on the side just as
well?

Control wheels in small airplanes are abominations, mainly there to
make the spamcan seem either like a car (Arrgh!) or a DC-3. How manly.
Note that the new crop of lightplanes have more sticks in them -
including sidesticks, which open up the cockpit a lot. Also, the trend
in large military (B-1, C-17) and commercial fly-by-wire planes is also
to sticks, since the leverage provided by a wheel is no longer
required. Boeing is an exception in it's commercial designs - the 777
could have used a stick. It will be interesting to see if the 787
keeps a wheel, now that the B-1 and C-17 are Boeing planes.
Airbus uses only sidesticks nowadays, I believe. There also have been
cardesigns using sidesticks, but they are not allowed (here) because of
regulations that forbid "drive by wire" somehow.

André

Andre,

It would be interesting to hear from the Diana designers why they chose
the sidestick. You are correct about Airbus, of course.

As far as using a short sidestick, try resting your forearm on your
desk, and pretend you are holding a sidestick. Simulate moving the
"stick" in pitch and roll. You will find that it is hard to get much
motion in pitch (especially back) when your arm is resting on
something. Roll is OK, but it's harder to roll right than left (using
the right hand). The solution on fly-by-wire planes such as the F-16
is to use a force-sensing stick, so there is little motion of the
stick. I think Airbus is similar. I've flown a bit in F-16s, and
really like it; very responsive and natural. Have not flown any manual
sidesticks so I'm neutral on them. I do like the short center stick on
my LS6 - I often fly with my left hand while entering data in my GPS,
and at high speeds/low altitudes (contest finish) usually have both
hands on the stick to prevent PIO's.

Kirk