sliding wings?

[[email protected]]

when I look at my eyeglass case, I see two closely overlapping
wing-type shapes that are being pulled apart for opening.

why would it not be worthwhile to extend wings this way for landing and
departure?

/iaw

[Bill Daniels]

I seem to remember a German University Akafleig (Academic Flying Group)
built and flew a telescoping wing glider in the 1960's. I recently heard a
proposal to use an inflatable airfoil structure that extended the wingspan
of a metal wing at low speeds. It seems very complicated but, if
successful, the payoff is huge for STOL performance plus high speed cruise

Bill Daniels

> wrote in message
oups.com...
>
> when I look at my eyeglass case, I see two closely overlapping
> wing-type shapes that are being pulled apart for opening.
>
> why would it not be worthwhile to extend wings this way for landing and
> departure?
>
> /iaw
>

[Smitty Two]

In article . com>,
" > wrote:

> when I look at my eyeglass case, I see two closely overlapping
> wing-type shapes that are being pulled apart for opening.
>
> why would it not be worthwhile to extend wings this way for landing and
> departure?
>
> /iaw

Do your eyeglass cases have ribs? Do you want to introduce a substantial
amount of complexity, perhaps roughly on a par with retractable landing
gear? Do you want to carry around a bunch of useless weight during
cruise just to give you a bit better STOL performance?

I'll keep an open mind, and would love to hear this idea fleshed out,
but for now, I think flaps are the weapon of choice here.

[[email protected]]

hmm...I am just asking. I am not an engineer, so I cannot calculate
loads and required strengths, but it would not seem to be too difficult
to integrate parallel ribs that slide along tracks with the extra wing.
or use some other wing strengthener that extends with the wing (e.g.,
a scissor-type extender). so maybe my eyeglass container solution
won't work, but flaps do not strike me as the only solution. yes, they
allow for a sharper angle of attack, but they do not gain much in terms
of wingloading. (and more importantly, in high speed, we need less
wing and drag, not more.)

inflatable would be nice, too... :-) modern materials like composites
should be pretty strong, too.

mostly just wondering why we do not get more wing when we need it...

/iaw

[Richard Lamb]

wrote:

> hmm...I am just asking. I am not an engineer, so I cannot calculate
> loads and required strengths, but it would not seem to be too difficult
> to integrate parallel ribs that slide along tracks with the extra wing.
> or use some other wing strengthener that extends with the wing (e.g.,
> a scissor-type extender). so maybe my eyeglass container solution
> won't work, but flaps do not strike me as the only solution. yes, they
> allow for a sharper angle of attack, but they do not gain much in terms
> of wingloading. (and more importantly, in high speed, we need less
> wing and drag, not more.)
>
> inflatable would be nice, too... :-) modern materials like composites
> should be pretty strong, too.
>
> mostly just wondering why we do not get more wing when we need it...
>
> /iaw
>


What flaps DO gain is Coefficient of Lift,
which makes more lift from the area you already have.

[Montblack]

wrote)
[snip]
> mostly just wondering why we do not get more wing when we need it...


Here's a possible solution:

http://www.jefflewis.net/autogyros.html
Autogyro History and Theory

http://www.groenbros.com/product/history.htm
More history - Groen Brothers Aviation

My idea for an Autogyro is for the smallish blades to be able to provide an
extra (25% - 40%) lift for take off and landing. Plane would tool along at
100-138 mph (without much of a speed penalty from the Autogyro blades) and
there it would be when you needed it - letting you land at 42 mph instead of
62 mph ...or maybe even 37 mph. <g>

Now, if you want some fun - incorporate small air-tip jets into the blades
for a little extra boost on take offs or landings. No tail rotor needed.
:-)

Again, just enough of an Autogyro to be a good little helper to the plane's
wings. (It sure wouldn't hurt having one in an engine out situation.)


Montblack

[Smitty Two]

In article om>,
" > wrote:

> hmm...I am just asking. I am not an engineer, so I cannot calculate
> loads and required strengths, but it would not seem to be too difficult
> to integrate parallel ribs that slide along tracks with the extra wing.
> or use some other wing strengthener that extends with the wing (e.g.,
> a scissor-type extender). so maybe my eyeglass container solution
> won't work, but flaps do not strike me as the only solution. yes, they
> allow for a sharper angle of attack, but they do not gain much in terms
> of wingloading. (and more importantly, in high speed, we need less
> wing and drag, not more.)
>
> inflatable would be nice, too... :-) modern materials like composites
> should be pretty strong, too.
>
> mostly just wondering why we do not get more wing when we need it...
>
> /iaw

Not being an engineer should give you a leg up.

The point I had hoped to make with the rib reference is that, I don't
quite see how the ribs in the extension will slide past the ribs in the
main wing.

[Karl-Heinz Kuenzel]

There have been a lot of experimentals with variable wingspan.

One you will find here

http://www.aviafrance.com/4806.htm

KH

> schrieb im Newsbeitrag
oups.com...
>
> when I look at my eyeglass case, I see two closely overlapping
> wing-type shapes that are being pulled apart for opening.
>
> why would it not be worthwhile to extend wings this way for landing and
> departure?
>
> /iaw
>

[Karl-Heinz Kuenzel]

Not variable wingspan, but variable wings

http://www.ctrl-c.liu.se/misc/ram/rk-i.html



http://www.ctrl-c.liu.se/misc/ram/is-1.html



KH



"Karl-Heinz Kuenzel" > schrieb im Newsbeitrag
...
> There have been a lot of experimentals with variable wingspan.
>
> One you will find here
>
> http://www.aviafrance.com/4806.htm
>
> KH
>
> > schrieb im Newsbeitrag
> oups.com...
>>
>> when I look at my eyeglass case, I see two closely overlapping
>> wing-type shapes that are being pulled apart for opening.
>>
>> why would it not be worthwhile to extend wings this way for landing and
>> departure?
>>
>> /iaw
>>
>

[Bill Daniels]

"Smitty Two" > wrote in message
...
> In article . com>,
> " > wrote:
>
>> when I look at my eyeglass case, I see two closely overlapping
>> wing-type shapes that are being pulled apart for opening.
>>
>> why would it not be worthwhile to extend wings this way for landing and
>> departure?
>>
>> /iaw
>
> Do your eyeglass cases have ribs? Do you want to introduce a substantial
> amount of complexity, perhaps roughly on a par with retractable landing
> gear? Do you want to carry around a bunch of useless weight during
> cruise just to give you a bit better STOL performance?
>
> I'll keep an open mind, and would love to hear this idea fleshed out,
> but for now, I think flaps are the weapon of choice here.

Come to think of it, one of the latest racing 15 meter wingspan racing
sailplanes has a 100% monococque wing - no ribs or spar.

[Karl-Heinz Kuenzel]

Hi, I don't think they built seven of those FS 29.



">>The "Akademische Fliegergruppe Stuttgart" (in short "Akaflieg") is a
scientific aeronautical association at the University of Stuttgart. Its aims
is to develop new methods in aircraft construction and to put them into
practice. The main focus is sailplane development<<"



Their aim is normally not making any sailplane production...

You can take a look on http://www.uni-stuttgart.de/akaflieg/e-home.htm

(Text in German).


KH

> schrieb im Newsbeitrag
oups.com...
>
> karl-heinz: thank you. interesting russian designs. alas, they do
> not tell us what the speeds and engine performances were. the IS-1
> actually flew, so this would have been interesting.
>
> I tried the aviafrance website, but cannot read french. fortunately, I
> can read German, and on a google search found yet another one---and
> this one from 1976 (i.e., not WW-2). it was for Akaflieg Stuttgart eV,
> which apparently tried a telescoping wing plane called fs-29.
> searching for airplane by name, I find indexes to "P. Lert, translator,
> The FS-29, a telescoplng-wing sailplane [Aerodynamics; Lee Waves;
> Sailplanes\FS-29], page 21" in Soaring Mag. more info is at
> http://www.sailplanedirectory.com/stutgar.htm, which says they built 7
> of these. [oops, just saw bill's post mentioning them, too.]
>
> smitty---having internal strengtheners slide by one another should not
> be too tough to accomplish, either.
>
>
> What is the drag contribution of the wings in cruise flight? Is it
> high? If so, this would make sense. Otherwise, not. Would it be
> feasible to build an airplane that is a 60mph/150mph (stall/cruise) in
> wing-extended config, and an 80mph/200mph airplane in non-wing-extended
> config (i.e., not deadly if the wing extension mechanism fails at
> landing time)? presumably, it would also save fuel.
>
> in the realm of tough technology, extending wings does not seem too
> difficult or error prone (e.g., compared to lowering wheels), whether
> it is telescoping, or covering two successive wings, or raising up a
> wing to become a biplane. the transition airflow might be tricky with
> the latter two, but apparently the Russians thought it would work in
> WW-2. also, if the wing does not extend, it wouldn't be so bad.
>
>
> richard---it was my misunderstanding that I thought they primarily
> change the angle of attack. but compared to more wing, they seem
> somewhat "limited."
>
> /iaw
>

[Bill Daniels]

At the time the FS-29 was built, carbon fiber construction was in its
infancy. Today, a monococque wing of carbon fiber sandwitch skins can be
constructed. This means the sliding outer wing panel can be made to slide
easily over a fixed inner panel.

Since you would want ailerons on the outer panel that would be the major
complexity. For an airplane, you can tolerate some less than perfect wing
aerodynamics with the wngspan extended since you are going to be flying 99%
of the time in cruise mode. Wing extended flight need only be stressed for
approach and landing airspeeds. Presumably with the wings retracted, the
strength would be more than adequate.

At high speed cruise, long wings are a liability and cruise speeds can be
increased with short wings. You'd want the cruise configuration short
enough that the wing flies at the best L/D AoA.

Think of a RV-8 like aircraft with a span variable between 30 feet and 18
feet. The sliding outer panels could cover retracted gear like gear doors.

Bill Daniels

> wrote in message
oups.com...
>
> karl-heinz: thank you. interesting russian designs. alas, they do
> not tell us what the speeds and engine performances were. the IS-1
> actually flew, so this would have been interesting.
>
> I tried the aviafrance website, but cannot read french. fortunately, I
> can read German, and on a google search found yet another one---and
> this one from 1976 (i.e., not WW-2). it was for Akaflieg Stuttgart eV,
> which apparently tried a telescoping wing plane called fs-29.
> searching for airplane by name, I find indexes to "P. Lert, translator,
> The FS-29, a telescoplng-wing sailplane [Aerodynamics; Lee Waves;
> Sailplanes\FS-29], page 21" in Soaring Mag. more info is at
> http://www.sailplanedirectory.com/stutgar.htm, which says they built 7
> of these. [oops, just saw bill's post mentioning them, too.]
>
> smitty---having internal strengtheners slide by one another should not
> be too tough to accomplish, either.
>
>
> What is the drag contribution of the wings in cruise flight? Is it
> high? If so, this would make sense. Otherwise, not. Would it be
> feasible to build an airplane that is a 60mph/150mph (stall/cruise) in
> wing-extended config, and an 80mph/200mph airplane in non-wing-extended
> config (i.e., not deadly if the wing extension mechanism fails at
> landing time)? presumably, it would also save fuel.
>
> in the realm of tough technology, extending wings does not seem too
> difficult or error prone (e.g., compared to lowering wheels), whether
> it is telescoping, or covering two successive wings, or raising up a
> wing to become a biplane. the transition airflow might be tricky with
> the latter two, but apparently the Russians thought it would work in
> WW-2. also, if the wing does not extend, it wouldn't be so bad.
>
>
> richard---it was my misunderstanding that I thought they primarily
> change the angle of attack. but compared to more wing, they seem
> somewhat "limited."
>
> /iaw
>

[[email protected]]

>>The point I had hoped to make with the rib reference is that, I don't
quite see how the ribs in the extension will slide past the ribs in the

main wing. >>

Just do away with conventional ribs. A double skinned cored curve
might be made with only a slight weight penalty, and construction would
be very simple. After all they would be used for just slightly more
than a 1"G" climb, or flare, and are at the tips of the existing wing
where bending loads are small. While your at it might incorporate
leading edge slats in the extendable section.
=====================
Leon McAtee
thinking exoskeleton

[[email protected]]

hmm...what would happen if the ailerons were mid-wing, rather than
end-of-wing? an outer-wing stall would occur before buffeting (ok),
then it would hit mid-wing (for how long?), then it would hit full
stall.

the real benefit might be a plane that would be much faster than an
ordinary RV-8 (if there is a big drag penalty to a big wing in fast
flight), and still land the same. getting the landing speed from 60mph
to 40mph is nice, but rarely important---ok, I am not flying STOL.

/iaw

[JJS]

"Bill Daniels" <bildan@comcast-dot-net> wrote in message ...
snip
>
> Since you would want ailerons on the outer panel that would be the major complexity. For an airplane, you can
> tolerate some less than perfect wing aerodynamics with the wngspan extended since you are going to be flying 99% of
> the time in cruise mode. Wing extended flight need only be stressed for approach and landing airspeeds.
> Presumably with the wings retracted, the strength would be more than adequate.
snip
>
Why not leave the ailerons where they are and extend the wings individually and differentially side to side to
initiate turns and to counter act the reduced aileron effectiveness? Or why not eliminate them entirely to further
reduce complexity and use differential wing extension as the sole control means?

> Think of a RV-8 like aircraft with a span variable between 30 feet and 18 feet. The sliding outer panels could
> cover retracted gear like gear doors.

Would it really be necessary to make that large a span difference? Would just 3 or 4 feet be sufficient?
snip

Obviously questions from an non aerodynamics educated individual.

Joe Schneider
8437R



----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
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[Bill Daniels]

"JJS" <jschneider@remove socks cebridge.net> wrote in message
...

> Why not leave the ailerons where they are and extend the wings
> individually and differentially side to side to initiate turns and to
> counter act the reduced aileron effectiveness? Or why not eliminate them
> entirely to further reduce complexity and use differential wing extension
> as the sole control means?
-------------

Hmmm.. Interesting thought - differential variable span for roll control.
I doubt that idea has ever been proposed before. I could work but it would
need a lot of testing - start with an RC model.

-------------
>> Think of a RV-8 like aircraft with a span variable between 30 feet and 18
>> feet. The sliding outer panels could cover retracted gear like gear
>> doors.

------------

> Would it really be necessary to make that large a span difference? Would
> just 3 or 4 feet be sufficient?

4 feet on each semi-span would make a lot of difference and be relatively
easy to construct.

Bill Daniels

[Rich S.]

> wrote in message
oups.com...
>
> when I look at my eyeglass case, I see two closely overlapping
> wing-type shapes that are being pulled apart for opening.
>
> why would it not be worthwhile to extend wings this way for landing and
> departure?

This is a solution in search of a problem.

Rich S.

[kd5sak]

"Rich S." > wrote in message
...
> > wrote in message
> oups.com...
>>
>> when I look at my eyeglass case, I see two closely overlapping
>> wing-type shapes that are being pulled apart for opening.
>>
>> why would it not be worthwhile to extend wings this way for landing and
>> departure?
>
> This is a solution in search of a problem.
>
> Rich S.
Isn't that pretty much how the B-2 is controlled?

Harold
KD5SAK

[Karl-Heinz Kuenzel]

From a book about the Horton Flying Wings

"... The Horton H VII had a new type of rudder installed. It consisted of
"tongues" that slid spanwise along the spar, and protuded from the tip for
additional wing tip drag. They worked very well, nevertheless the 20 H VII's
in production at Peschke at the end of the war, had conventional drag
rudders..."

around 1944

KH

[Morgans]

"JJS" <jschneider@remove socks cebridge.net> wrote

> Why not leave the ailerons where they are and extend the wings
individually and differentially side to side to
> initiate turns and to counter act the reduced aileron effectiveness? Or
why not eliminate them entirely to further
> reduce complexity and use differential wing extension as the sole control
means?

Seems like there would be a very large adverse turning drag problem. You
want to turn left, so you extend the right panel. That increased the drag
on the right, and that is not what we want to happen.

Also, the panel would have to be very quick, or the response would be very
slow and sloppy.
--
Jim in NC

[Morgans]

"kd5sak" > wrote

> Isn't that pretty much how the B-2 is controlled?

Not really. On a B-2, there is a plain flap, or spoiler, on the top and the
bottom of the wing, out towards the tip. Yaw is done by extending the top
and bottom flap, about equally. You turn to that side, in a flat turn,
though.

To roll and turn left, the spoiler on the top left goes up. Fine tuning of
the yaw and roll, and so-forth, is done with the other flaps, with the fly
by wire doing all ot the thinking.

This is all a gross over simplification, of course.
--
Jim in NC

[Capt. Geoffrey Thorpe]

> wrote in message
oups.com...
>
> when I look at my eyeglass case, I see two closely overlapping
> wing-type shapes that are being pulled apart for opening.
>
> why would it not be worthwhile to extend wings this way for landing and
> departure?
>
> /iaw
>

But, wouldn't the eyeglasses fall out onto the runway?

:-)
--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
Spell checking is left as an excercise for the reader.

[Richard Lamb]

Bryan Martin wrote:

> Fowler flaps, like those found on most single engined Cessnas and most
> airliners, do increase the area of the wing as they deploy. They extend
> backward as they deploy, acting to increase the wing chord instead of the
> wing span.

True, of course.
The extra area of the flap equipped part of the wing adds surface.
But seldom in excess of .2 to .3 chord - and that only on the flapped
area of the wing.

The real pay off is the increased CLmax.

Abbott & Von Doenhoff has a very detailed study of various flap systems.

The example shown is a 65-210 section.
RN = 8 meg.

Basic section CLmax is about 1.4.

With fully extended Fowler type flap that goes up to a little over 2.4.

However, the angle of attack at CLmax actually goes DOWN!

From peak at about 15 degrees plain to roughly 8 at full deflection.

That one even surprised me...

>
> in article . com,
> at wrote on 2/26/06 11:25 AM:
>
>
>>(snip)
>>
>>richard---it was my misunderstanding that I thought they primarily
>>change the angle of attack. but compared to more wing, they seem
>>somewhat "limited."
>>
>>/iaw
>>

The deciding factor will be weight and structural difficulties.

One thought - fat airfoils don't like to go fast.
Thin airfoils don't like to go slow.

Seems like we'd have to have a fat airfoil for the main section so
that the thin airfoil could fit inside.

Just about exactly backwards...

Might be why we don't see very many telescoping wings around?

Richard

But it sure works great for eyeglass cases!

[[email protected]]

> One thought - fat airfoils don't like to go fast. Thin airfoils don't like to go slow.
> Seems like we'd have to have a fat airfoil for the main section so that the thin airfoil could fit inside.

next stupid question for the day. if this is so, why not have wings
that change shape? flaps, I know---but again, flaps seems pretty
rudimentary. there must be some better solutions, now that building
materials have become a lot better than they were 80 years ago.

actually, all my questions are ignorant of the very first question---is
it possible to estimate how much faster would an ordinary piston
airplane, say a C172, would be if we eliminated *all* wing drag? [and,
yes, presume it is still flying and not straight down, where my
eyeglasses have fallen into ;-)] if the answer is not much, then I am
to blame for having started a useless discussion.

[[email protected]]

Rich S. wrote:
> > wrote in message
> oups.com...
> >
> > when I look at my eyeglass case, I see two closely overlapping
> > wing-type shapes that are being pulled apart for opening.
> >
> > why would it not be worthwhile to extend wings this way for landing and
> > departure?
>
> This is a solution in search of a problem.
>

Doesn't a swing wing accomplish pretty much the same thing?

--

FF

[Bill Daniels]

> wrote in message
oups.com...
>
> Rich S. wrote:
>> > wrote in message
>> oups.com...
>> >
>> > when I look at my eyeglass case, I see two closely overlapping
>> > wing-type shapes that are being pulled apart for opening.
>> >
>> > why would it not be worthwhile to extend wings this way for landing and
>> > departure?
>>
>> This is a solution in search of a problem.
>>
>
> Doesn't a swing wing accomplish pretty much the same thing?
>
> --
>
> FF

Yes, for supersonic fighters. Swept wings aren't a good choice for light
aircraft.

For slow propeller airplanes, the telescoping wing does have its
attractions. It's a way to keep the slow stall speed required for single
engine airplanes and stilll get a fast economical cruise. It probably
wouldn't help the venerable C-172 but an airplane that was already
aerodynamically clean might benefit quite a lot.

The airfoil could be any reasonable one for light aircraft. The outer wing
wouldn't make the innner wing more than an inch thicker. In addition to the
speed, another benefit would be a softer ride in turbulence with the much
higher wing loading.

Bill Daniels

[Richard Lamb]

wrote:
>>One thought - fat airfoils don't like to go fast. Thin airfoils don't like to go slow.
>>Seems like we'd have to have a fat airfoil for the main section so that the thin airfoil could fit inside.
>
>
> next stupid question for the day. if this is so, why not have wings
> that change shape? flaps, I know---but again, flaps seems pretty
> rudimentary. there must be some better solutions, now that building
> materials have become a lot better than they were 80 years ago.
>
> actually, all my questions are ignorant of the very first question---is
> it possible to estimate how much faster would an ordinary piston
> airplane, say a C172, would be if we eliminated *all* wing drag? [and,
> yes, presume it is still flying and not straight down, where my
> eyeglasses have fallen into ;-)] if the answer is not much, then I am
> to blame for having started a useless discussion.
>

Well, admission is the first step in recovery :^)

Wing drag comes in two flavors:

There is induced drag from the creation of lift
and parasitic drag, which is a catch all for everything else.


Induced drag will vary directly according to CL.
Think of it as:
Di = Cdi q S

or another way:

Di = (CL^2 / Pi AR) S q

where:
AR = b^2 /S
b = wing span
Cd = coefficient of drag
Cdi = Cd induced
q (rho - not Que) = dynamic pressure (psf)
S = wing Surface (area)


Parasitic drag (Dp) is a little tougher to get an accurate handle on.
First step is to estimate a coefficient for it (Cd).
For wing only, we can refer to the lift/drag curves for a starting guess.

Dp = Cdp S q

then:

Dtotal = Di + Dp

To answer the 172 example we need to know the airfoil and area
Plug and grind, and out will pop - an estimate.

There is an added complication as Cessna uses neither a constant
chord - nor a constant airfoil.

That would mean doing a span wise summation of Cdx to get a better
guess. Messy and WAY beyond anything I want to type up this early
in the morning.

But for true masochists, refer to "Theory of Wing Sections" by
Abbott and Von Doenhoff.

Might be a good idea to have MathCad handy too...


Richard

[[email protected]]

wrote:
> hmm...what would happen if the ailerons were mid-wing, rather than
> end-of-wing?

Instead of having a smaller outer panel extend out of a larger fixed
section, how about having the larger section (with the ailerons) slide
out over a smaller fixed section?

Yeah, I know the control linkages could get interesting, but there are
ways to do this mechanically, hopefully without too much of a weight
penalty. Or, fly-by-wire, perhaps?

Rob

[[email protected]]

Bill Daniels wrote:
> > wrote in message
> oups.com...
> >
> > Rich S. wrote:
> ...
> >> This is a solution in search of a problem.
> >>
> >
> > Doesn't a swing wing accomplish pretty much the same thing?
> >
> > --
> >
> > FF
>
> Yes, for supersonic fighters. Swept wings aren't a good choice for light
> aircraft.

IIUC, sweeping the wing backwards has an adverse effect on stall
which is often offset with washout or twist.

How about swinging the wing forward instead?

>
> For slow propeller airplanes, the telescoping wing does have its
> attractions. It's a way to keep the slow stall speed required for single
> engine airplanes and stilll get a fast economical cruise. It probably
> wouldn't help the venerable C-172 but an airplane that was already
> aerodynamically clean might benefit quite a lot.
>
> The airfoil could be any reasonable one for light aircraft. The outer wing
> wouldn't make the innner wing more than an inch thicker.

It would be easier to have the outer wing be the moving part from
a structural perspective, but then you have a longer chord on the
wing tip.

Another even more exotic alternative would be to design a wing
that could shape to higher or lower lift and drag airfoils. Actually
the Wright Brothers sort of did that.

Always happy to muddy the waters.

--

FF

[Smitty Two]

I think this telescoping wing idea is interesting from an academic
standpoint, but I don't think the engineering challenges are going to
make it practical.

However, for the sake of discussion, what about telescoping the wings at
the fuselage instead of the outboard ends? Could dovetailed spars be
strong enough to allow the wings to be extended during TOAL and extended
for cruise? Would a cabin width of extra wingspan suffice to accomplish
the rather nebulous objectives?

[Richard Lamb]

Smitty Two wrote:
> I think this telescoping wing idea is interesting from an academic
> standpoint, but I don't think the engineering challenges are going to
> make it practical.
>
> However, for the sake of discussion, what about telescoping the wings at
> the fuselage instead of the outboard ends? Could dovetailed spars be
> strong enough to allow the wings to be extended during TOAL and extended
> for cruise? Would a cabin width of extra wingspan suffice to accomplish
> the rather nebulous objectives?

I'd agree with the academic aspect of the idea.

A rather more practical approach is the variable geometry approach used
by the F-111, F14, etc.

The MOST important point being that the wings are then SWEPT for high speed
flight. This feature is important in delaying the onset of shock waves and
the controllability and exponential drag increase associated with real speed.

For high SUBsonic speed check out the various high lift devices already in
use on a 737. They are (relatively) simple mechanically, provide an
astounding increase in low speed lift, and are fairly light in weight.

Richard

[Bill Daniels]

"Richard Lamb" > wrote in message
nk.net...
> Smitty Two wrote:
>> I think this telescoping wing idea is interesting from an academic
>> standpoint, but I don't think the engineering challenges are going to
>> make it practical. However, for the sake of discussion, what about
>> telescoping the wings at the fuselage instead of the outboard ends? Could
>> dovetailed spars be strong enough to allow the wings to be extended
>> during TOAL and extended for cruise? Would a cabin width of extra
>> wingspan suffice to accomplish the rather nebulous objectives?
>
> I'd agree with the academic aspect of the idea.
>
> A rather more practical approach is the variable geometry approach used
> by the F-111, F14, etc.
>
> The MOST important point being that the wings are then SWEPT for high
> speed
> flight. This feature is important in delaying the onset of shock waves
> and
> the controllability and exponential drag increase associated with real
> speed.
>
> For high SUBsonic speed check out the various high lift devices already in
> use on a 737. They are (relatively) simple mechanically, provide an
> astounding increase in low speed lift, and are fairly light in weight.
>
> Richard

Don't forget this was done by university students in 1972 with the first
flight of a 19 meter span glider on 15 June 1975. The pilot was able with
hand power alone to extend the span in flight from 13 meters to 19 meters
and retract it again. See: http://www.uni-stuttgart.de/akaflieg/fs29.html
(Use Google language tools to translate the German into English.)

Under 250 knots, swept wings don't help at all and the lift devices on a 737
are indeed complicated and require a lot of power to operate and a lot of
engine power to overcome their drag. And, telescoping wings are not a
possibility for a 600 knot aircraft.

A single engine light plane, like the FS-29, would slide a hollow outer
wing section over the inner section. The outer section would be totally
monococque with no spars or ribs. The skins would be one 10mm thick carbon
fiber/PVC foam sandwich as is the standard on sailplanes today. The aileron
would be on the outer section operated by a sliding torque tube. The
extension and retraction of the outer wing panels could be done with a
simple recurculating ball lead screw.

The outer section would slide all the way to the fuselage covering things
like fuel filler caps and retracted landing gear leaving a smooth wing
surface top and bottom.

If the maximun span were the same as a 172 or 34 feet and the minimum span
were 24 feet like a RV-4, then one could expect the slow speed performance
of the Cessna and the high speed performance of the RV although with modern
airfoils, I'd suspect the slow speed performance would be better than the
172.

I think it would be worthwhile for the same reasons the students gave in
1975.

a.. Greater wing area variability than with fowler flaps.
a.. High aspect ratio wing for slow flight, with smaller induced drag.
a.. A rigid wing profile with a narrow laminar bucket that can always be
flown at the optimal AoA.
a.. Based on the Stuttgart experience, cheaper to build than Fowler flaps.

Bill Daniels

[Rich S.]

"Bill Daniels" <bildan@comcast-dot-net> wrote in message
...
>
> If the maximun span were the same as a 172 or 34 feet and the minimum span
> were 24 feet like a RV-4, then one could expect the slow speed performance
> of the Cessna and the high speed performance of the RV although with
> modern airfoils, I'd suspect the slow speed performance would be better
> than the 172.

You're going to a heck of a lot of trouble to improve the low speed
performance of an RV-4, seems to me.

Rich S.

[Montblack]

wrote)
>>Now, if you want some fun - incorporate small air-tip jets into the blades
>>for a little extra boost on take offs or landings. No tail rotor needed.

> Google "Fairey Rotodyne." Been done before.
> There aren't a whole lot of new ideas out there.


http://www.jefflewis.net/autogyros.html
Autogyro History and Theory

http://www.groenbros.com/product/history.htm
More history - Groen Brothers Aviation

The Rotodyne is in one of the links. I've been a HUGE backer of bringing
back the Rotodyne idea ....2005 vs. 1950 materials and technology. Don't get
me started on that 22 B-B-B-B-Billion dollar V-22 Osprey boondoggle
deathtrap.

There are Rotodyne movie clips out there that are fun.


Montblack

[wright1902glider]

Please excuse my rudimentary knowledge of aerodynamics... BUT...

Telescoping wingtips would appear to change the aspect ratio of a wing
in a very interesting way. That is, in span, rather than chord. I can't
say what happens at higher speeds, but down here on the low end of the
envelope, increasing span has a very large effect on roll and yaw
rates. What happens to alierion & rudder effectiveness when the tips
are extended? Or would you have to make both control surfaces larger to
gain the necessary rates? Just wondering.

It could work, but I agree that flaps and slats sound simpler to build
and maintain.

Harry

[Richard Lamb]

wright1902glider wrote:
> Please excuse my rudimentary knowledge of aerodynamics... BUT...
>
> Telescoping wingtips would appear to change the aspect ratio of a wing
> in a very interesting way. That is, in span, rather than chord. I can't
> say what happens at higher speeds, but down here on the low end of the
> envelope, increasing span has a very large effect on roll and yaw
> rates. What happens to alierion & rudder effectiveness when the tips
> are extended? Or would you have to make both control surfaces larger to
> gain the necessary rates? Just wondering.
>
> It could work, but I agree that flaps and slats sound simpler to build
> and maintain.
>
> Harry
>
Aspect Ratio IS an important parameter, so there is some logic to the
madness...

http://www.home.earthlink.net/~tp-1/ar-aoa.jpg
(ain't gonna try to do graphs in ASCII)

Di = (CL^2 / Pi AR) S q
(Note that AR is in the Divisor above)

Assuming that we have two wings of the same area, higher AR should result
in lower induced drag.

BUT, all other things being equal, the higher AR wing will weigh more.

Thus...

Dform = Cf S W q is going to offset some of that gain in form drag.

As for the RATES question above, forget trying to maintain a snappy
roll rate on a longer wing. Larger ailerons (at least large enough
to really roll that puppy) are going to take a LOT more force to
operate. Likely more than an unboosted pilot can provide.

[[email protected]]

I believe the C172 has a stall speed of 50knots (57mph), the RV-4 of
54mph. it would seem that this is not a useful calculation to obtain a
lower stall speed.

actually, my guess is that a wing extension would be of interest mostly
if it allowed faster and less turbulent cruise. getting the stall
speed further down is not going to attract the speed tuner crowd. so,
getting something that keeps a common 60mph stall speed telescoped and
a 70mph stall speed if the telescope fails [i.e., unpleasant but
landable], but increases cruise speed by 10-15mph would sound
attractive.

aside, there are times when a smaller wing and faster landing speed
would also be a good idea even for landing (in turbulent winds).

/iaw

[[email protected]]

actually, the carter copter is an interesting example. their FAQ
claims

Wings are very efficient at high speed, but can't provide enough lift
as the aircraft slows down. In most aircraft, the wings are sized
significantly larger than they need to be in cruise flight so that the
pilot can fly slower for landing. Most airplanes also have some type of
high lift device, such as flaps, which further decrease the minimum
flight speed of the aircraft, but add weight and complexity to the
wing. The CarterCopter has a very simple wing, sized much smaller than
a conventional aircraft of similar size, because the wing only needs to
support the aircraft at high speeds.

they want to reach 500mph with their autogyro, although they don't tell
us what engine they need for this. the concept is similar---big wings
only for landings and takeoffs, although I really do wonder if
something flapping above me is simpler than a fixed wing extender.

/iaw

[Richard Lamb]

wrote:

> I believe the C172 has a stall speed of 50knots (57mph), the RV-4 of
> 54mph. it would seem that this is not a useful calculation to obtain a
> lower stall speed.
>
> actually, my guess is that a wing extension would be of interest mostly
> if it allowed faster and less turbulent cruise. getting the stall
> speed further down is not going to attract the speed tuner crowd. so,
> getting something that keeps a common 60mph stall speed telescoped and
> a 70mph stall speed if the telescope fails [i.e., unpleasant but
> landable], but increases cruise speed by 10-15mph would sound
> attractive.
>
> aside, there are times when a smaller wing and faster landing speed
> would also be a good idea even for landing (in turbulent winds).
>
> /iaw
>

Hold up a second, Vowel.

I don't mean to be a pain about this, but the ONLY way you'd see ANY
benefit from this is if the weight increase is minimal AND the increase
in wing area is - well - maximal?

Let me offer up some more of that ugly stuff...

Going back to...
L = Cl S q

using q = (sigma V^2)/295 (V in knots, TAS)
(sigma = density Ratio)
( = 1 at sea level)
L = Cl (Sigma V^2 /295) S

then solving for V

V = 17.2 Sqrt(L / Cl Sigma S)

Simplified for stall speed at sea level...

Vstall = 17.2 (WEIGHT / CLmax S) Since Lift = Weight

Work out the ratio of weight increase / wing area increase to determine
how that plays out for any real example.

My read on it is pretty straight forward.

Short of high temper unobtanium, it's a moot point.
Limited to less expensive materials, the weight INCREASE for this trick
would be significant, and would quite possibly increase stall speed.

Unless we put FLAPS on the extension part... <BSEG>...


Richard

[[email protected]]

hi richard: could you possibly give me some numerical illustrations?
I am not sure where your numbers are coming from (17.2?, 295?), but
this is probably just my ignorance. obviously, going from 0 to 1 sqft
of wing is a useful weight/lift tradeoff... :-) is your point that the
current wing size (of any plane) is already the optimal weight/lift
tradeoff? strange that better materials over the last 50 years would
not have changed the optimum.

regards,

/iaw



> Let me offer up some more of that ugly stuff...
>
> Going back to...
> L = Cl S q
>
> using q = (sigma V^2)/295 (V in knots, TAS)
> (sigma = density Ratio)
> ( = 1 at sea level)
> L = Cl (Sigma V^2 /295) S
>
> then solving for V
>
> V = 17.2 Sqrt(L / Cl Sigma S)
>
> Simplified for stall speed at sea level...
>
> Vstall = 17.2 (WEIGHT / CLmax S) Since Lift = Weight
>
> Work out the ratio of weight increase / wing area increase to determine
> how that plays out for any real example.
>
> My read on it is pretty straight forward.
>
> Short of high temper unobtanium, it's a moot point.
> Limited to less expensive materials, the weight INCREASE for this trick
> would be significant, and would quite possibly increase stall speed.
>
> Unless we put FLAPS on the extension part... <BSEG>...
>
>
> Richard

[Richard Lamb]

wrote:

>
> hi richard: could you possibly give me some numerical illustrations?
> I am not sure where your numbers are coming from (17.2?, 295?), but
> this is probably just my ignorance. obviously, going from 0 to 1 sqft
> of wing is a useful weight/lift tradeoff... :-) is your point that the
> current wing size (of any plane) is already the optimal weight/lift
> tradeoff? strange that better materials over the last 50 years would
> not have changed the optimum.
>
> regards,
>
> /iaw

I'll give it a try, but you owe me lunch now!


No, not trying to say that all wings are already optimal.
Especally for all missions.

Just that one must look carefully at
proposed performance gains / weight increase.

Write this down: "It's ALL about WEIGHT"

Material gains over the last 100(!) years have been amazing.
For instance, can you imagine a wooden 747
Think I'm kidding?
Check out this 600 passenger design proposal by Bel Geddess,
presented at the New Your Worlds Fair in 1940.
And it's a SPAN LOADER, too!

http://www.home.earthlink.net/~tp-1/ged.pdf


>

the mystery numbers?
Nothing mysterious here.
It's just arithmetic.

refer to page 25 of Aerodynamics for Naval Aviators

Anybody have a link to this?
It is an excellent starting point for basic aerodynamics.


>>Going back to...
>>L = Cl S q

This is the basic lift equasion (well, one of many forms)
Rearrange that equasion to solve for L, CL, S, or even q.

Cl is the coeffecient of lift that we are looking at.

S is Wing Surface Area is Sq Feet

q (rho) is dynamic pressure in pounds per square foot.
q = 1/2 density * velocity squared
Density in Slugs per cubic ft.
V in feet per second).

>>using q = (sigma V^2)/295 (V in knots, TAS)

295 is a conversion factor that converts FPS to knots

Greek leter Sigma is used for density ratio.
That's ambient pressure / standard day pressure
At sea level standard day, sigma is 1, and drops out.


>>L = Cl (Sigma V^2 /295) S

So if sigma is 1 then L = CL V^2 S / 295

>>then solving for V
>>
>>V = 17.2 Sqrt(L / Cl Sigma S)

17.2 is ~ the square root of 295

>>Simplified for stall speed at sea level...
>>
>>Vstall = 17.2 (WEIGHT / CLmax S) Since Lift = Weight

Stall speed implies Maximum Coeffeceint of Lift for a given airfoil.

We need as much lift as weight for straight and level flight,
So L = W = L (are the same)


Well, it's late and I'm bushed.
I've read that over several times, and now it doesn't make sense
to me either.

We'll do lunch another day, ok?

Richard

[Richard Lamb]

I couldn't find any links to an on-line copy of
"Aerodynamics for Naval Aviators".

But google did turn up a couple hundred links to
copies for sale. Prices range from about $10 to
just under $25.

[Montblack]

("Richard Lamb" wrote)
[snip]
> Material gains over the last 100(!) years have been amazing.
> For instance, can you imagine a wooden 747
> Think I'm kidding?
> Check out this 600 passenger design proposal by Bel Geddess, presented at
> the New Your Worlds Fair in 1940.
> And it's a SPAN LOADER, too!


http://www.home.earthlink.net/~tp-1/ged.pdf
That's neat ...in a 1929 -1940 kind of way.


Montblack

[Richard Lamb]

Montblack wrote:

> ("Richard Lamb" wrote)
> [snip]
>
>> Material gains over the last 100(!) years have been amazing.
>> For instance, can you imagine a wooden 747
>> Think I'm kidding?
>> Check out this 600 passenger design proposal by Bel Geddess, presented at
>> the New Your Worlds Fair in 1940.
>> And it's a SPAN LOADER, too!
>
>
>
> http://www.home.earthlink.net/~tp-1/ged.pdf
> That's neat ...in a 1929 -1940 kind of way.
>
>
> Montblack

I particularly enjoyed the side by side comparison of the creature comforts.

Olde fashioned elegance New fangled jet
------------------------ ---------------

Main Lounge 36 ft high
9 decks 2 decks
3 Kitchens
13 pantries Peanuts
Library Bad movie
writing rooms
2 public dining rooms
The main dining room coverts into a dance floor for 100 couples
orchestra platform
3 private dining rooms capable of feeding 40 people
4 deck tennis courts
6 shuffle board courts
6 quoits pitches
library
writing room
1 gym with dressing rooms and showers 12 chemical toilets
1 men's Solarium w/16 couches and a masseur
1 women’s Solarium w/16 couches and a masseuse
1 children’s playroom
1 doctors office with waiting room
Barber shop
hairdressers salon
2 bars Bar cart
1 store
1 huge promenade deck
1 Veranda Cafe seats 90
18 single state rooms
81 double staterooms
24 suites w/ baths 606 seats w/ fold-down tables - 32" pitch
179 sleeping rooms
Air-conditioning Air-conditioning

[Morgans]

"Richard Lamb" > wrote

> I particularly enjoyed the side by side comparison of the creature
comforts.

Being a mechanical kind of guy, I particularly enjoyed the "5 minute
inflight engine change capability," with the machine shop repairing the bad
one, and returning it to spares, (one of 6 extra) ready for return to duty.

Or how about sitting out on the sun deck for a while, during the 100 mph
flight? It would be easy to get burned, with that wind chill factor, no?
<g>
--
Jim in NC

[[email protected]]

I will be happy to take you to lunch when you are in RI and I am in
airport vicinity. I will even pay for the drink if you can answer the
following simple question. For 100 points and the jackpot... ;-)

An RV-10 has a span of about 32 ft, wing area of 148 sqft and a wing
loading of 18.6 lb/sqft. It cruises at around 190mph
(optimistically). It's stall speed is 57mph.

Let's presume its wings were telescopic---which of course they are not.
Let's presume that fully extended they are still what they are. Now
presume in full flight, I could take off 1/3 of the wing. For your 100
points, how does the expected stall and cruise speeds change? [For
extra credit, assume a reasonable weight increase. hmmm...how much
does an empty aluminum wing structure weigh? I guess this could even
be fabric---it would be used only during landing.]

regards,

/ivo

[Richard Lamb]

wrote:

> I will be happy to take you to lunch when you are in RI and I am in
> airport vicinity. I will even pay for the drink if you can answer the
> following simple question. For 100 points and the jackpot... ;-)
>
> An RV-10 has a span of about 32 ft, wing area of 148 sqft and a wing
> loading of 18.6 lb/sqft. It cruises at around 190mph
> (optimistically). It's stall speed is 57mph.
>
> Let's presume its wings were telescopic---which of course they are not.
> Let's presume that fully extended they are still what they are. Now
> presume in full flight, I could take off 1/3 of the wing. For your 100
> points, how does the expected stall and cruise speeds change? [For
> extra credit, assume a reasonable weight increase. hmmm...how much
> does an empty aluminum wing structure weigh? I guess this could even
> be fabric---it would be used only during landing.]
>
> regards,
>
> /ivo
>

Grrrr.

Ok, but don't start the clock until I hit "send"?
You left out the weight. (I Tol' you to 'Write That Down!')

148 square feet on a 32 foot span implies a chord of 5.25 feet or 63 inches.

ASSUMING a gross weight of 2700 the 57 mph stall would imply a CLmax of 2.2.
(That has GOT to be flaps down!)

Removing 1/3 of the span (.666 * 32') leaves 23.3' span
23.3' span * 5.25' chord gives (111.888) call it 112 square feet.
Predicted stall speed (with these numbers) looks like 65 mph.

ADDING 1/3 to the span gives 42.6' span and 224 square feet area.
Predicted stall speed (with these numbers) looks like 46 mph.

A guess at cruise numbers would be foolish. Too many unknowns.
And no way to break the wing drag out of the overall without better info.

Would the short wing version fly faster?
Maybe - maybe NOT - because the short wing would be flying at a higher angle
of attack - with corresponding higher drag...

So - purest speculation....

Based on the above at cruise:
For the Van's wing, CL of .197. aoa ~ -1 degree. Cd ~ .0076
For the short wing, CL of .26 aoa ~ -1/2 degrees .0077
And the long wing, CL of .13 aoa ~ -1-1/3 degrees .008

And, most bizarre of all, the long wing version MIGHT even cruise FASTER!

HOwZaT?

By cruising at a higher altitude...
Up where the air is thinner and colder!



Ham and cheese on Rye, please?

Richard

[Richard Lamb]

Richard Lamb wrote:

> wrote:
>
>> I will be happy to take you to lunch when you are in RI and I am in
>> airport vicinity. I will even pay for the drink if you can answer the
>> following simple question. For 100 points and the jackpot... ;-)
>>
>> An RV-10 has a span of about 32 ft, wing area of 148 sqft and a wing
>> loading of 18.6 lb/sqft. It cruises at around 190mph
>> (optimistically). It's stall speed is 57mph.
>>
>> Let's presume its wings were telescopic---which of course they are not.
>> Let's presume that fully extended they are still what they are. Now
>> presume in full flight, I could take off 1/3 of the wing. For your 100
>> points, how does the expected stall and cruise speeds change? [For
>> extra credit, assume a reasonable weight increase. hmmm...how much
>> does an empty aluminum wing structure weigh? I guess this could even
>> be fabric---it would be used only during landing.]
>>
>> regards,
>>
>> /ivo
>>
>
> Grrrr.
>
> Ok, but don't start the clock until I hit "send"?
> You left out the weight. (I Tol' you to 'Write That Down!')
>
> 148 square feet on a 32 foot span implies a chord of 5.25 feet or 63
> inches.
>
> ASSUMING a gross weight of 2700 the 57 mph stall would imply a CLmax of
> 2.2.
> (That has GOT to be flaps down!)
>
> Removing 1/3 of the span (.666 * 32') leaves 23.3' span
> 23.3' span * 5.25' chord gives (111.888) call it 112 square feet.
> Predicted stall speed (with these numbers) looks like 65 mph.
>
> ADDING 1/3 to the span gives 42.6' span and 224 square feet area.
> Predicted stall speed (with these numbers) looks like 46 mph.
>
> A guess at cruise numbers would be foolish. Too many unknowns.
> And no way to break the wing drag out of the overall without better info.
>
> Would the short wing version fly faster?
> Maybe - maybe NOT - because the short wing would be flying at a higher
> angle
> of attack - with corresponding higher drag...
>
> So - purest speculation....
>
> Based on the above at cruise:
> For the Van's wing, CL of .197. aoa ~ -1 degree. Cd ~ .0076
> For the short wing, CL of .26 aoa ~ -1/2 degrees .0077
> And the long wing, CL of .13 aoa ~ -1-1/3 degrees .008
>
> And, most bizarre of all, the long wing version MIGHT even cruise FASTER!
>
> HOwZaT?
>
> By cruising at a higher altitude...
> Up where the air is thinner and colder!
>
>
>
> Ham and cheese on Rye, please?
>
> Richard
>
>
>
Oh yes! As for the weight increase question...

It's still 2700 pounds gross, but it's a two seater now...
:)

Richard

[[email protected]]

the german expression when one is not getting something is that one is
standing on the (phone) line, which is why nothing is coming in. so, I

am still trying to figure out what you were computing.

putting your posts together, if you instruct engineers, some examples
with units would be helpful. (take this from someone who teaches
financial economics for a living.)

Vstall = 17.2 (WEIGHT / CLmax S) Since Lift = Weight

I believe CLmax and S are both under the division, because more S
should give me lower stall speed. Now, your recent post tells me that
CLmax = 2.2 . hmmm, this would lead me to plug in

57mph = 50 knots =?=?= 17.2 * (2700 lbs / [2.2 * 112sqft])

(I don't know the units on 17.2 or 2.2.)

so, the clock is still ticking... ;-).