BKB-1 flying wing glider

[Genghis the Engineer]

Bit of a longshot this, but does anybody know of the existence of any film (better still, digital video) of the BKB-1 tailless glider being displayed? In particular it flew what was called a "tumble", a sort of pitch autorotation from which it could be recovered at will. This was in the 1950s and 1960s, the only example of the aircraft was destroyed in the 1970s in an accident.

There was a related aeroplane called the "Kasperwing", named after Witold Kasper, the chap who used to display the BKB-1 - and anything of that would be equally interesting.

Basically I've read descriptions of what it did, but would love to actually see it (and if I'm honest, freeze-frame it).

G

For those not in the know...

http://1000aircraftphotos.com/Contributions/1169A.jpg

[treadigraph]

Dunno about any film I'm afraid but I do remember reading about this act some years ago - it may have been in Flying. There was some debate about how the wing generated lift - I seem to recall (and this is a very shaky memory) that the pilot (?) had a theory about a vortex over the wing which allowed him to do the tumbles and recover. Personally I would have thought it was a highly exaggerated form of the sort of loop performed by some WW1 replicas - very tight!

If the article was in Flying, then I'd guess Peter Garrison wrote the article and it was probably part of a technical piece on lift and wings generally.

I'd loved to have seen it in the flesh; if you do find some film, I hope you'll be able to share it with us!

By the way, I always associated Manfred Radius with the act, but I gather he flew aeros in a more conventional glider, and also did a night display with fireworks!

Cheers,

Treadders

[MReyn24050]

Genghis the Engineer
I found the following on a website called THE WING IS THE THING
(T.W.I.T.T.), I know it doesnt sound too good but it appears genuine.
A VHS tape of Stefanie Brochocki's presentation on the design history of the BKB-1 (Brochocki,Kasper,Bodek) as related by her father Stefan Brochocki exists. It is reported to be an interesting look into a very unique glider. The second part of this video has Henry Jex telling about his experiences with the development and flight of the radio controlled Quetzalcoatlus northropi (pterodactyl) used in the Smithsonian IMAX film "On The Wing". I have removed the URL to the site as it is an advertisement. Should you require it I can PM it to you.

Mel

[Sedbergh]

Genghis

The BK wasn't the only flying wing glider - there was a whole series designed by Fauvel in France - normally numbered AV** (for aile volante). There was an AV 36 flying at the International Vintage Glider rally in Germany last year.

I've heard that they can also do the "flick loop" but have never seen it. Try sticking a query on the Vintage Glider Club website forum

[Rocket2]

there was a whole series designed by Fauvel in France - normally numbered AV**
Indeed there was - the RAF Gliding Association owned one (an AV-36?) better known as the Budgie which was based at Bicester until it was sold around 1980. Sadly I never flew it, but the loops looked incredibly tight by todays standard.

[Sedbergh]

Of course there were the Horten flying wing gliders as well. They're trying to get one airworthy in Germany but they don't look as if they could do anything so undignified as a "tumble"

I can PM you a photo of the AV 36 but I'm too iggerant to be able to post it on prune. :ugh:

[treadigraph]

Send it to me Sedbergh and I'll post it for you - there's a Fauvel at Old Warden owned by John Alllison.

[email protected]

Ghengis, you around - did you find out any more?

I'll see if I can find that Flying article if I get a mo to get in the loft.

[Genghis the Engineer]

I've actually done a lot of work on the subject over the years - I *think* I've seen pictures of most of the various gliders / aeroplanes produced to this model (Fauvel / Brochoki / Kasper / Horton / Northrop / de Havilland), and corresponded with various people who had flown them or were around (including Stephanie Brochoki, who was extremely helpful).

However, it's this pitch autorotation (often called the tumble) that really interests me. Basically what I'm really after, is the chance to actually see that motion myself - of any flying wing, but the BKB-1 was the aeroplane most associated with it and the only one which seems to have consistently and predictably recovered each time.

G

[Wunper]

G
I have none of the references you are after and think I might have posted you this link before but in case I haven't I think this is an excellent site
http://www.nurflugel.com/Nurflugel/Papers/papers.html
Maybe Ted Hull or Chris Wills of the VGC could help you? they both have loads of stills and film footage
Good luck in your quest.
Cheers
W

[Sedbergh]

Interesting - you'd think that the amount of wing sweep-back shown on the BKB-1 would make it more resistant to the "tumble" than the straighter winged Fauvels.

But that of course might help the pitch control when stopping the tumble. Although assuming that Fauvel pilots could also do tumbles, I would like to think that they must have had some kind of choice about their attitude when stopping the manoevre!

[Wunper]

I think it was in "The Clouds Remember" that I read a handling comment on the Sopwith Triplane describing how it could be made to do really tight loops and tumble backwards "like a tumbler pigeon".
I'll dig it out later, I assume the mechanism would be something to do with the relationship between the drag on the upper wing at high alpha and the thrustline in a very shortcoupled airframe fitted with a powerful elevator. (there may be a dollop of precession from the engine as well)
On the BKB-1 tumble I might be displaying crass ignorance here but isn't this akin to what happens when you drop a schoolboys' wooden ruler (as opposed to an engineers' rule G ;) ) and it swizzles chordwise to the floor?
W

[treadigraph]

Wunper, you just transported me back three decades to school where we used to chuck flat bits of wood (actually the slats out of the back of a broken chair) in such a manner that they would rotate chordwise as you describe making an interesting whirring noise and clearly exhibiting some sort of aerodynamic effect, though I don't remember what - and I'm not sure I want to embarrass myself in front of my neighbours by experimenting with a short length of TGV in the garden!

I assume that the BKB-1 was doing positive tumbles - assuming that it was adequately stressed, I wonder what would happen if it pitched "forwards" into a negative tumble?

Sedbergh, received your Fauvel pics at home and emailed them to myself at the office - but they haven't arrived :{ . I'll sort them on Thurs.

Treadders

[Genghis the Engineer]

According to the various reports that I've read, the one time they tried a nose-down tumble, the rate and g-forces were about double what had been experienced afterwards, and the seat structure had to be rebuilt due to overstress.

G

[Wunper]

I was wrong on the title of the book ref in my earlier post it was
"Farewell to Wings" (Illustrated by Leonard Bridgeman published by Temple press 1964) by the late great Cecil Lewis.
He had this to say about the Sopwith Triplane
It was a little beauty. The Rotary engine, tank and pilot were all bunched close together, so it could turn sideways or head over heels like a tumbler pigeon. Its three mainplanes carried all the area necessary for the load in such a small span that you could throw the Triplane from side to side like a leaf. Being from the Sopwith stable, all the controls were nicely balanced and the machine handled like a polo pony. The 'Tripe' vies with the Pup for pride of place in my heart for sheer flying pleasure
And
Set the engine at three-quarter throttle and wind the tail well back and the Tripe would loop indefinately. I once did 21 loops in a row!
It has just reminded me of what super writing style Cecil Lewis had. Sorry for hijacking the BKB-1 thread!
W

[treadigraph]

Here are Sedbergh's Fauvel pics:

http://www.tpsconsult.co.uk/dump/images/fauv1.jpg

http://www.tpsconsult.co.uk/dump/images/fauv2.jpg

Very nice too!

[trilander]

The AV 36 from Bicester ended up at Old Warden and is on display in the hanger. yes loops were tight