Conditions for a startup vortex? Quasi-static aerodynamics? I need help!

[space_case]

Long story short, I did a 'quasi-static' analysis on a morphing aircraft with a telescoping wing. Now I need to run some numbers on actuator power calculations. I need to come up with the maxmimum speed that the wing can telescope and the discrete aerodynamic models (quasi-static analysis) can hold true.

Somebody suggested to me once that the 'startup vortices' are a large factor in this case.

Don't startup vortices arise from viscous effects during the initial acceleration of an aircraft?

Does the larger(?) Re# of the flow over the chord prevent the effects of the spanwise flow from being noticeable?

Re here is ~3x10^6

I know this is a bit of an OT line of questioning, but I'm backed into a corner here and thought that some of you may have some useful input.

-Kenny

[Tom Harper]

I doubt that I can contribute anything useful but I have a couple of questions.

Why would the start up vortex have anything to do with max telescoping velocity? Sounds more like a mechanical engineering problem.

What span wise flow?

[space_case]

Why would the start up vortex have anything to do with max telescoping velocity?

They may or may not have anything to do with one another. I need to know at what point the unsteady (transient) aerodynamic effects become prevelant.

I may have confused things by bringing up the 'starting vortex'. This was just a suggestion made to me.

What span wise flow?

When the wings telescope, they are inducing a velocity along the wing spanwise. They are being 'pushed' sideways through the air just like the wing is being 'pulled' forward by the propeller. In fact, I think that this spanwise flow would be opposite of the normal spanwise flow that exists on finite wings.

[Sparky Paul]

I know the problem has been solved. Back in the '50s Blackhawk was saving a country being terrified by a criminal who lofted MiG-15s with telescoping wings and tails from submarines!.. these would morph into the full airplane, which were naturally no match for Blackhawk's float-equipped F-90s... The Lockheed "Thud-star".. I believe.. :) HAWKAAAAA!
Anyway, I doubt the tip activity would prevent much of an obstacle to a telescoping wing pushing out.. and it might possibly aid the retraction.
The problem would be the layered structure for the wing parts.

[space_case]

My whole paper is about minimizing the loads on the telescoping structure. This is done by tailoring the spanwise lift distribution (using a full-flying section at the tip) to yield a lower net force on the inboard section.

I never heard of the morphing Mig-15!!??

[biber]

The Akaflieg Stuttgart has once built a fullsize glider with telescoping wings.
It was called fs29 tf .
May it be helpful or not, here's the link anyway:
http://www.uni-stuttgart.de/akaflieg/fs29.html

biber

[Sparky Paul]

I don't see the MiG in this list of "bad guy" planes..
http://ourworlds.topcities.com/blackhawk/models/mod_bair.html
On extending/extruding a wing section, the aft and upward bending loads would probably demand a very good structural design to not bind as the loads increase with the span.
Something like a nesting hydraulic boom, with two booms, and possibly only airpressure instead of a fluid to keep the weight down.

[Ollie]

Think different(ly).

You have two states (long span and short span) a switch between them. In a short time the switch wants zero lift force, zero drag force and minimized other forces like friction. The detail of the switch (snap) time is unlatch, move the wing tip panels, relatch. It comes to my mind like a enscapment, tic and tock. Perhaps a brief maneuver like vertical whip stall. Briefly the air speed is zero when the aircraft stops and the wing switches state.

[space_case]

Perhaps a brief maneuver like vertical whip stall. Briefly the air speed is zero when the aircraft stops and the wing switches state.

Well, Ollie, this is exactly a point I'm going to make during the presentation. Why not just climb veticaly and bleed off speed, then extend the wing when there is zero dynamic pressure on it?

This thought along with a couple of other ideas occured to me along the way. I decided to go ahead with the project considering straight and level flight (which the mission profile *may* call for).

Here are the two families of lift distributions. The 'Controlled' case is the with wing tip being rotated, and the 'Uncontrolled' case is extending the wing straight out.

You can see what happens to the controlled lift distribution as the wing span grows from 4 to 12 meters. The outboard lift goes negative so that there is a nominally zero net force (yes drag is considered also) at the inboard 'hinge point'. At the same time, the aircraft angle of attack has to increase, causing the larger lift values in the center of the wing.

Frankly, I think this plot begs to have a woman's face photoshoped ont it!

http://i3.photobucket.com/albums/y53/aerospace_case/lift.jpg

[Ollie]

Perhaps you have read Chapter Four, pp 59 to 63 from "Wing Theory" by Robert T. Jones.

Fig. 4.4 Develoment of lift, Fig.4.5 -flying into a sharp-edged gust and Fig. 4.6 -staring from rest in a compression fluid. Perhaps you could use the data from above Figs. 4.4, 4.5 and 4.6. Perhaps, with the swing wing, you snap the change in less than 6 chords of flying position.

[Sparky Paul]

Your graph shows why wings don't telescope. :)

[space_case]

Perhaps you have read Chapter Four, pp 59 to 63 from "Wing Theory" by Robert T. Jones.

Fig. 4.4 Develoment of lift, Fig.4.5 -flying into a sharp-edged gust and Fig. 4.6 -staring from rest in a compression fluid. Perhaps you could use the data from above Figs. 4.4, 4.5 and 4.6. Perhaps, with the swing wing, you snap the change in less than 6 chords of flying position.

I don't have this book, though it sounds like it would be helpful.

Paul, you may be right. It is possible, the question is, does it buy you anything when all is said and done?

I have built a span morphing aircraft, on a small scale, that more than doubled it's span in flight. I used mouse trap springs and a folding wing concept.

I wonder where my picture went??

edit: this network blocks things like photobucket!

[Sparky Paul]

I was looking thru Aviation Week today, and noticed there's a slip-wing UAV being developed. The entire wing pivots on the fuselage, one side going forward the other going aft, for high-speed flight.
Rutan had something like that a few years back.
Mechanically it would less complex than telescoping or swinging.. the aerodynamics would be "interesting".. :)

[space_case]

the aerodynamics would be "interesting".. :)

There's no question about that. You have a large shift in the nuetral point while the CG remains stationary. It *has* been done (ref F-14 (RIP) and B1-B).

[space_case]

Oops, reread. You're talking about a whole different animal.

[Sparky Paul]

http://www.nasa.gov/centers/dryden/news/FactSheets/FS-019-DFRC.html

[space_case]

Interesting, I would have liked to reference that plane in the paper.

[nauga]

Paul, you may be right. It is possible, the question is, does it buy you anything when all is said and done?
Biber already referenced the Stuttgart Akaflieg telescoping-wing glider, and NASA (Dryden, as I recall) has flown a wing that increased span and area in flight. I don't think it was telescoping, though. It's also been evaluated for other platforms. It gains you a few things, some good, some bad.

Good: Ability to have high wing loading when you need it for things like gust response, and low wing loading for things like cruise. It also allows you to carry something with reasonable aspect ratio for efficiency in a small space.

Bad: Weight and complexity.

The trade study is different for every application :cool:

How's Pax River these days?

Nauga,
the day trader

[Sparky Paul]

Here's another that NASA did..
BTW, I fly with Dan Garrabrant.. he's about 85 now, and still going strong.http://www.dfrc.nasa.gov/gallery/photo/HyperIII/HTML/E-20464.html

[nauga]

Ah, here's the one I was thinking of. I was afraid to post that I thought it was inflatable, but it turns out to be the case. Yikes.

http://www.dfrc.nasa.gov/gallery/Photo/InflatableWing/Small/ED01-0273-1.jpg

Nauga,
who thought he heard a pop.

[space_case]

Ah, here's the one I was thinking of. I was afraid to post that I thought it was inflatable, but it turns out to be the case. Yikes.

http://www.dfrc.nasa.gov/gallery/Photo/InflatableWing/Small/ED01-0273-1.jpg

Nauga,
who thought he heard a pop.

Now this one I referenced. It is *the* span morphing aircraft of any real size today (that I know of).

PAX is great. More business with every BRAC. G-dub's new helo is here, we just got a Global Hawk. The Navy only bought 2 and they have way better 'avionics' than the USAF version. I'm trying to pick up some JSF scraps here soon myself. Property values are obscene. You been here before? I've been here for a year.