HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Jul 11, 2012, 03:12 PM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
3,285 Posts
Quote:
Originally Posted by kleinaberfein View Post
I am watching and learning

Jens
Learning?On one of my threads?Shurely shome mishtake
My secret plan(keep this to yourself)is to get this thing to free fly in a reasonable manner with the wing set as a plank,which Herks has proven can be done,and increase the sweep in stages.As to what happens if I can get a moderate success,designing a r/c version with flight variable sweep is well beyond what Im capable of.We shall see.
Stuart
Stupot46 is offline Find More Posts by Stupot46
Reply With Quote
Sign up now
to remove ads between posts
Old Jul 11, 2012, 04:19 PM
Closed Account
Joined Jul 2009
745 Posts
You better believe it Stuart, and this thing has really got me tuned in. variable sweep flying wing ... sounds nuts but why not. And why should you not be able to design it? You are already on the way to doing it.

Jens
kleinaberfein is offline Find More Posts by kleinaberfein
Reply With Quote
Old Jul 11, 2012, 06:20 PM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
3,285 Posts
Bit more done on the centre.The infill piece is 3/8",very soft.I cut a lot away,put back the mid portion as it felt too flimsy.The piece above is to link the pivots,this will also be cut out as much as possible(2mm lt.ply) I intend to put a length of carbon either side of it to stiffen things up.
The wing-I managed to induce a small amount of twist when I glued it together.
In the first pic dimensions are-750mm from pivot to tip,150mm root and 70 tip.The second is 110 tip.The wider one looks better in the plank configuration,I would appreciate views from the more technically minded amongst us.
Regards Stuart
Stupot46 is offline Find More Posts by Stupot46
Reply With Quote
Old Jul 11, 2012, 06:33 PM
Herk
HerkS's Avatar
Virginia USA
Joined Jun 2007
1,645 Posts
Stuart - I worked as an engineer on the Navy's F-14 program from about 1970 (when the Navy was supposed to buy the F-111) until about 1987 when I got a different assignment. It is really fun to see you working on this. Bravo!!!

I really like this forum. Even though there are not a lot of people participating, the ones who are involved are generally building, flying --- or at least doing something!!!

Carry ON! You are definitely on a good track here. I am very interested in this.

Herk
HerkS is offline Find More Posts by HerkS
Reply With Quote
Old Jul 12, 2012, 12:01 AM
Closed Account
Joined Jul 2009
745 Posts
This thing is soooo cool, HerkS you are quite right there. This is a only a small community here, but it is a community doing stuff and some of it like this is pretty far out there.

Jens
kleinaberfein is offline Find More Posts by kleinaberfein
Reply With Quote
Old Jul 13, 2012, 01:39 AM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
3,285 Posts
Thanks guys.As the saying goes I'd never have made it without you(and the rest of the brilliant contributors)
A question-should I build a simple pod?Most of the planks I've looked at have one,my original idea was a simple keel for hand launch.I'm thinking a pod would make weight adjustment easier.
I think I'll go with the broader of the wing shapes and Herks earlier suggestions on control surfaces.Blenderm tape hinges with thin piano wire at right angles so I can fix them at different angles.
Cog-Norm posted a simple diagram over in flying wings.I'll do some drawings,see what I come up with and ask you guys to check it.
Regards Stuart
Stupot46 is offline Find More Posts by Stupot46
Reply With Quote
Old Jul 13, 2012, 06:15 AM
Herk
HerkS's Avatar
Virginia USA
Joined Jun 2007
1,645 Posts
Good morning Stuart

When I set up the plank I used these connectors at all of the external control horns.

That made the adjustment very simple - just loosen the screw, adjust then retighten.

http://www.amazon.com/gp/product/B00...ls_o03_s00_i00
HerkS is offline Find More Posts by HerkS
Reply With Quote
Old Jul 13, 2012, 06:34 AM
Closed Account
Joined Jul 2009
745 Posts
Well a pod would be easier to use for CoG adjustments Stuart but it is ofcourse a bit more work to build.

Jens
kleinaberfein is offline Find More Posts by kleinaberfein
Reply With Quote
Old Jul 13, 2012, 06:42 AM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
3,285 Posts
Thanks Herks.I think I've seen those in the lhs.
Regards Stuart.
Stupot46 is offline Find More Posts by Stupot46
Reply With Quote
Old Jul 13, 2012, 03:50 PM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
3,285 Posts
Quote:
Originally Posted by kleinaberfein View Post
Well a pod would be easier to use for CoG adjustments Stuart but it is ofcourse a bit more work to build.

Jens
Missed your post this a/m Jens-I think you're right.I'll go with a keel.I'm trying to just use what materials I have to hand,a trip to a decent hobby shop isn't on at the moment.I do have a lot of foam offcuts(HoVIII sections are stacked high under my bench!)so I could cut a pod- like keel from that.
Stuart
Stupot46 is offline Find More Posts by Stupot46
Reply With Quote
Old Jul 13, 2012, 04:29 PM
Closed Account
Joined Jul 2009
745 Posts
Sounds good Stuart, keep it simple here. This is an experiment and likely you might have to make some changes after the first flights. The super nice version of this is for later after you have crashed the experiment a dozen times to get it right.

Jens
kleinaberfein is offline Find More Posts by kleinaberfein
Reply With Quote
Old Jul 13, 2012, 09:06 PM
internet gadfly
nmasters's Avatar
Colorado
Joined Aug 2006
2,165 Posts
I'm wondering about how you plan to move the CG in flight. As you sweep the wings aft the aerodynamic center moves a lot at first then more slowly as the sweep angle increases. If you balance it as a plank 2 degrees of sweep probably would be enough to put it into a dive, assuming that most of the mass is fixed in the center. On the other hand if you balance it as a 20 degree swept wing then you can move the wings forward a few degrees for pitch up and back for pitch down. I think it's going to be very hard to avoid over-control at small starting sweep unless you can get very fine control.

--Norm, who has too many other irons in the fire
nmasters is online now Find More Posts by nmasters
Reply With Quote
Old Jul 14, 2012, 12:23 AM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
3,285 Posts
Norm,that is something that I have thought about.If I can get this thing to make decent free flights with the wing in 4 or so positions I'll be a happy man.Taking it from there will require more knowledge of the sort that you and the more experienced among us have in abundance.And a more sophisticated radio than mine.
The mechanics of the thing are the simple part-my latest thoughts are to use some sort of composite material for the wing roots,pivots and the linking braces.
If these components can be made stiff enough and to close tolerances a pair of plastic ball races in each should be sufficient to ensure free movement of the wings in flight.
For now,as Jens says simplicity is the key.
Regards Stuart

for the
Stupot46 is offline Find More Posts by Stupot46
Reply With Quote
Old Jul 14, 2012, 03:02 AM
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
Joined Jan 2011
1,688 Posts
I've been watching this thread sense it started. I was thinking in the back of my mind the same thing about the CG changing with sweep. What was not in my mind was what Norm points out, that shift is not liner. After reading Norms post the gears started turning again, and to my way of thinking, (Danger Will Robinson, Danger!) the simple way to get the movement would be to plot out the CG points for each degree of sweep, from plank to where ever full sweep ends up. Once you get those graphed out you will have your non liner curve that a set of cams can be plotted from. Attached to the wings at the swivel points, placing the cams underneath the R&P, a pull/pull weight and slide can be attached, moving the weight along the non liner pull of the cams. Things like travel distance of the weight / radius of cam, etc., would need to be figured out, but me thinks the over all idea is shiny.

I would not bother for the test bird, but could be a good way to go in the real build. No fancy radio and programming, no extra servos and/or electronics. Just a set of simple mechanical cams tied in with the wing movement.

Just an after thought, but I would almost bet that the cam face would fit real close somewhere along the golden spiral. Maybe not... It was just more gears turning. (see disclaimer in red above)

Mark
Quick61 is offline Find More Posts by Quick61
Reply With Quote
Old Jul 14, 2012, 05:19 AM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
3,285 Posts
Mark I like this.In fact I think it's a genius idea.I used to make my own at work;heart shaped/ constant rate of traverse was used a lot,so I know this would work.Shiny indeed!
Best regards Stuart
Stupot46 is offline Find More Posts by Stupot46
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Best electric plane in 16 mph wind? Sailor03 Electric Plane Talk 42 Nov 23, 2012 02:40 PM
Discussion Why do airplanes take off in to the wind? - news article jduvall Electric Plane Talk 65 Jun 15, 2012 07:29 AM
Discussion Make Sure Your Wind Turbine Is In The Wind Big Foot 48 Life, The Universe, and Politics 0 Apr 04, 2012 09:22 AM
Help! DJI Naza wind issue!!!! (help needed with throttle up issue in wind) Arxangel Multirotor Talk 11 Mar 07, 2012 01:47 AM
Sold ~closed~ WINDSHEAR II Aircraft - Fuel - Engines and Accessories (FS/W) 2 Oct 13, 2011 11:15 PM