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Old Jul 04, 2012, 04:48 PM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
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Been a- musing again.Showing g/d how to divide a circle;the compasses had geared legs.So drew up the simplest form of gear teeth on some depron and pinned them to the board.
If these were connected by a scissors arrangement to a nut on a screwed rod motor shaft I think a strong mechanism could be made without being too heavy.
Could an extension /opposite end of the shaft be made to move a c/g compensating weight(different hand threads on each section?)Or could this be more accurately achieved by a separate servo.
Stuart
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Old Jul 05, 2012, 12:33 AM
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Stuart, I need to ask a dumb question, is this idea intended to move a weight (to alter C/G) laterally in the aircraft or longitudinally? Somehow I am not sure where you want to go with this. Sorry

Jens
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Old Jul 05, 2012, 05:26 AM
I don't like your altitude
Stupot46's Avatar
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Jens,the gear teeth are the roots of a swing wing idea.If this could be made to work,the c/g would need to move longitudinally to compensate.Just a bit of mental doodling.
Regards Stuart
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Old Jul 05, 2012, 06:03 AM
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Aha ok now I get it, yeah that would work. I think I have seen something like this used by Kyosho on an impeller jet they offered for awhile. CoG change was not needed in that plane but it was a conventional aircraft.

Jens
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Old Jul 05, 2012, 11:21 AM
I don't like your altitude
Stupot46's Avatar
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I did a search on here and google,only one mention of meshed gear swing wing,and that was a 'if I was going to' comment.
A couple of posting remarked on the difficulty of achieving and holding an even angle of sweep using servos;even if one wing had more pressure on it than the other,say in a turn,this system should hold them together.The gears would need to be of the correct profile for the diameter(I used to know how to draw these ,but that mental cupboard is now empty)
Found some Acetal ball races online,37mmo/d,8mmi/dx12mm which would be ideal.
The diameter of the segment would be the same as the root foil on a Horten type wing with a separate centre section;some drawing to do here,but I think the amount of movement needed would allow a gap free fit to be maintained between wing and centre.
Also mentioned in the search was the work done by NASA on the F14 which seems to conclude that pivot points well outside the airframe centre line are preferable.Box ticked.
Materials for the disc/gear teeth-nylon for the gears,embedded as a segment into a composite disc which would have 'spars' attached extending as far as possible into the wing.
Any links to a similar set up would be appreciated,also any comments/ideas.
Regards Stuart
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Old Jul 05, 2012, 11:58 AM
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United States, IN, Indianapolis
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An f-14 swing study

or the wings could simply mech to themselves
without the center rack gear.
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Old Jul 05, 2012, 12:09 PM
I don't like your altitude
Stupot46's Avatar
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Quote:
Originally Posted by birdofplay View Post
An f-14 swing study

or the wings could simply mech to themselves
without the center rack gear.
Brilliant!thanks a lot for the animation.The rack is a great improvement.
Is that a model that's been produced or just a study?
Btw your text seems to have arrived fragmented.
Regards Stuart
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Old Jul 05, 2012, 02:39 PM
Herk
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Hi Stuart -
if you really wanted to build something like this you could start out with wings that can be manually positioned with various degrees of sweep. You could explore the concept without having to deal with the weight and complexity of an in-flight variable system.

Since we are on the nurflügel forum, I assume that you are thinking of a flying wing aircraft. The idea of being able to vary the sweep from near zero to something perhaps like 45 degrees is quite interesting. At some point one might want to be able to do that in flight, but fixed-variable would be an excellent way to start the exploration.
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Old Jul 05, 2012, 03:22 PM
I don't like your altitude
Stupot46's Avatar
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Hi Herks,yes it would be a wing.What got me started on this was Richards discussion Planks versus swept wings.The mechanism above is ideal,but I would imagine a whole lot of other aspects of the idea will need thrashing out before a small test plane could be built
Some sort of a compromise airfoil would be required,;am I correct in thinking that planks need some reflex?If so it would have to be provided by control surfaces;over the whole length of the wing?
A small depron model with the wings lockable in various positions would be,as you say a good place to start,
Regards Stuart
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Old Jul 05, 2012, 03:35 PM
Herk
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Personally I think that a plank could fly well with reflex airfoils plus a modest amount of twist.

Or -- as you said the trailing edge could be used to provide reflex when a plank -- and twist when swept -- if the TE is segmented.

Three segments on each wing should work pretty well. The two inner segments could be adjustable but manually positioned and fixed when flying - the outer one working as elevon.

Really my only point I guess is that the idea can be worked on and experimented with and still kept very simple. Elaborate systems can bring so many issues that the basic exploration gets buried in complications.
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Old Jul 06, 2012, 06:46 AM
I don't like your altitude
Stupot46's Avatar
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Herks,in Richards discussion you speculated on a plank with no verticals using drag rudders for stability.If and when I do a trial version I think drag rudders will figure in the design.Otherwise tips would need to be adjusted at each sweep position.
I'm thinking at this stage a simple free flight model to test out the concept,plenty of hills around here to chuck one off.
Regards Stuart
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Old Jul 06, 2012, 07:12 AM
Herk
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I just maidened the plank. Check that thread for my report.
The dragerons worked perfectly - I was really impressed. I suspected the drag would not be enough to do much - was very wrong about that.
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Old Jul 06, 2012, 10:40 AM
I don't like your altitude
Stupot46's Avatar
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I am really quite excited about the work you are doing,and your success with it.As I said on your thread,it will be interesting to see how much vertical you can lose.If you manage to eliminate the tips that will be a whole new ball game.
As to the drag rudders,I was quite surprised by the effect they had on my HoX chuck glider.That project may bear some reappraisal.
Regards Stuart
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Old Jul 07, 2012, 03:32 PM
Herk
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Plank experiment is ready for the next test flight. Central fin and rudder removed, tip fins installed ---- AND --- - I installed the gyro. The gain is set quite low but it does seem to be working as it should. Next flights will be interesting. I won't be getting out for a couple of days, --- must attend to other obligations.
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Old Jul 07, 2012, 04:12 PM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
3,325 Posts
Quote:
Originally Posted by HerkS View Post
Plank experiment is ready for the next test flight. Central fin and rudder removed, tip fins installed ---- AND --- - I installed the gyro. The gain is set quite low but it does seem to be working as it should. Next flights will be interesting. I won't be getting out for a couple of days, --- must attend to other obligations.
Two days of waiting with bated breath
Herks,you've worked wonders with this so far,and I suspect more of the same will ensue.
Best regards Stuart
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