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Old Apr 20, 2012, 12:46 PM
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Air Brakes on a delta wing...

I posted the following thread in the modelling science thread, but I guess it doesn't get as much traffic thats relevant as this forum...

Can anybody help?


(Whilst searching RCG looking for further ideas I stumbled across this forum... blimey RCG is HUGE!)

Anyhow I guess this is the best place to post my question, as I seem to be going round in circles at the moment...

I have an X8 which will be used for FPV. The airframe has been substantially reinforced. I have elongated the elevons and split them in two. Luckilly my flying partner and spotter is Angelos, head honcho at Spartan RC who's primary products are world leading Heli avionics. He has already made an onboard mixer so the split elevons work as rudders/ airbrakes and of course conventional elevons.

I have also modded a pair of FunJet ULTRA Wings so they are a direct swapout for the stock winglets on the X8 (to be used as rudders and controlled by onboard stabalisation, an offshoot from the upcoming Spartan Vortex flybarless heli control system) which can also be used as proportional airbrakes.

So thats 'flaps', 'rudders' as airbrakes... and still I want more! I am trying to find the best place to position pop up airbrakes (as in large gliders) on the wing for maximum effect/ and the theoritical best place for 'nuetral' effects on pitch when deployed if such a theory exists.... (although the stab system should be able to counteract any issues, I would like to minimise them)

This is a bonkers project... The X8 does have a 'ground effect' problem and with mine being a little heavier than most with all the kit it will have onboard (large pack capacity and large motor, let alone all the electronics, cameras and various lighting systems etc etc) and I would like to try and land the way I allways do (in steep, flair and drop).

The other reason is that I like night flying, my existing rig has amused/bemused many hundreds of people. I would like to increase the 'erratic' nature of my flying by hitting all the brakes on a flat out run, and diving slowly (ish!!) then straighten everything out and zoom off again. It's running 6s with just over 1KW as opposed to the old Zagi 480 based machine that only had 500w on 3s and was as about as near as you can get to having a flying brick!!!

If any of you have any experiance/ ideas/ links to further info It would be greatly appriciated....

To recap... where do I place pop up airbrakes on a Delta Wing?

Many thanks,

Paul

p.s. I have no affiliation with Spartan, other than being friends with the guys, this project is making Angelos shrug his shoulders, laff, or go red in the face, this is a mad persons lone project!!!
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Old Apr 21, 2012, 07:30 AM
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oxford uk
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Seriously?

Has no one ever tried airbrakes on a delta??

Loads of views and yet no comments, even if it was just to take the mick out of me?

Will have to revisit the subject during the week, I'm carrying on with the rest of the build, so many seperate systems onboard!

Paul
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Old Apr 21, 2012, 10:19 AM
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have you thought of a parachute!?~~~~H
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Old Apr 21, 2012, 09:51 PM
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Mr Blue... yes I have but that will be a one use and jettison or trail job... I would like repeatability. But I do appreciate your (and anyone else's) input

Paul
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Old Apr 22, 2012, 01:14 AM
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Have you thought of building a Simitar?

They have most of the performance qualities you're describing.

http://www.rcgroups.com/forums/showthread.php?t=502443

Consruction articles start on page 2 of this posting.

On my Classic, I can come screeming downline and then just chop the throttle and then full up elevons.

It noses up just a tad then flys at a slow crawl.

Then jam the throttle open and return the elevons to neutral and away it goes.

Plus if you still want to ad airbrakes, the fuselage sides rear of the wing is where I would put them.

Tight Turns,

Claude
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Old Apr 22, 2012, 11:01 AM
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Claude ... That was a fascinating tangent to go off on whilst some glue was drying, bookmarked for future reference. Whilst I did some traditional balsa tissue and dope gliders in my teen years my FPV ships are all foamies (although with bits of trad building thrown in for re-inforcement!)

Many thanks for placement tip - it's the only one I have had despite several hundred views of my various requests for help

My big glider and those I have researched on the net seem to be about 1/3 down the wing from the leading edge, obviously a Delta wing works very diferently. Great thing about foam is that you can experiment and move stuff around without much time or hassle.

Thanks for sharing link, all those 'exotic' wing profiles, so much work has been done in the past that seems to get largely ignored these days which is a real shame. I love the look of reverse deltas

Paul
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Old Apr 23, 2012, 08:38 PM
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Quote:
Originally Posted by yogz View Post
If any of you have any experiance/ ideas/ links to further info It would be greatly appriciated....

To recap... where do I place pop up airbrakes on a Delta Wing?
http://www.rcgroups.com/forums/showt...0#post21413957
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Old Apr 24, 2012, 01:18 PM
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Brilliant!!

Many thanks for sharing. Although mine is a very different 'bird' it proves the concept, and I now have some idea of how much 'down flap' will be required.

I really appreciate the help (my split ailerons can be totally configured, as crow brakes, as 'flap down' and 'normal' operation on the outer portion. It really does a huge slowing down job (albeit on a much much lighter rig!)

The airbrakes themselves will just be 'adding' to the effect methinks (even if its just in a small way!)

Regards

Paul
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Old Apr 24, 2012, 10:18 PM
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Originally Posted by yogz View Post
Although mine is a very different 'bird' it proves the concept, and I now have some idea of how much 'down flap' will be required.
The foam wing you show in the first post is similar to the Me-163 but higher aspect ratio and apparently a bit less sweep. Here's a drawing of the flaps on the Me-163 and anther placement of a split flap on a flying wing. Lower surface split flaps slow a plane down more than the same size surface on top.

--Norm
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Old Apr 26, 2012, 03:48 PM
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Thank you VERY much for pointing me in the right direction yet again! I think my split ailerons are in the ballpark with reference to the 106 (pic attatched, wing in background gives idea of percentage of control surface and relative to tip and root)

And the 'belly flap' is a whole new area for me. My pop up brakes are looking more weedy all the time now (Angelos says 'about as effective as putting your hand out of a car window to slow it down!!') But I could fairly easilly do the mod for the 'upsidedown' flap.

I truely appreciate your help and links Norm. Once shes flying about I will be sure to post a vid here so you can see your advise in action!

Paul
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Old Apr 26, 2012, 04:56 PM
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Yes, pleas, post video! That's why I do this stuff

--Norm
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