Horton Flying Wing

So that's what those "split flaps" on the wingtips do on the B-2. You're two for two.

SaparotRob said:

So that's what those "split flaps" on the wingtips do on the B-2. You're two for two.

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They're called an "elevon".

Koopernic said:

Argentina is also where Reimer Horton in 1950 made a speech before the Argentinian Aeronautics Society talking about the "radar camaflauge" effect of wood.

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Horten certainly discussed this in Argentina and again during interviews in the 1970s, but the theory that the Ho IX or Go 229 were designed with the intent of masking their radar signature is bogus. There is no mention in any surviving paperwork, nor was there any mention by Horten whilst under interrogation post war in Britain. He even offered himself and his ideas to British aviation firms, none of which took him or his offer seriously. In the National Archive there is quite a bit of surviving Horten paperwork and there is no mention whatsoever about this.

The whole 'stealth' aspect of the Horten flying wings in the Nat Geo documentary is retrospectively applying the concept to these aircraft as a result of the B-2 Spirit. There was never any intent by Horten or the RLM to incorporate radar masking of any sort into the designs.

Horton's original intent was to build a fast bomber. It just sort of got changed into a fighter, probably because the Germans were desperate to stop the Allied air attacks.

The Ho.IX was to be a fighter/bomber design from the start, and a follow-on to the current piston powered project.
The Ho.XIII was the actual bomber design and there were a couple versions - one version of the XIII was modified by "committee" when Goering had Junkers and Messerschmitt engineers get involved. Reimar went and restored the design to it's original concept, but it was never built, as all of this transpired in early 1945.

The wood structure the Hortens used on the Ho.IX V2 was similar to the wood structure used on the LaGG-3 and La-5. I think the Hortens knew that wood and the shape of their flying wings would help in reducing radar cross section, but their primary goal was to build a high performance flying wing fighter rather than a stealth aircraft. If you look at the Ho.IX, they were going in the right direction as far as blended shapes but this was more for aerodynamics rather than defeating radar. The blended airframe shapes have to be planned calculated for that part of the technology to work. (Lockheed did this by adopting data taken from a paper written by Pyotr Ufimtsev, a Russian scientist that provided the final catalyst for aerial stealth technology to work.) The air intakes of the Ho.IX were huge chunks of metal that would have lit up like a candle under radar and the canopy frame and landing gear doors would have produced a condition called "radar creep", further expanding it's RCS. Despite this, the Ho.IX would have had a lower RCS than conventional aircraft and I think Northrop proved this when they built a Ho.IX replica about 12 years ago and tested it's RCS which IIRC had no metal on it.

"Stealth Technology does not involve a single technical approach but rather a complex synthesis of many." Bill Perry, Under Secretary of Defense for research and engineering, 1980

So what I am taking from this is that the difficulties in building a flying wing aren't as great as I thought, but neither are the benefits.

The benefits of a flying wing are that drag penalties are reduced, as there is no fuselage and vertical/horizontal stabilizer.

The main issue with a flying wing is stable flight. The Ho.VI and Ho.IX as well as Northrop's N9M were stable in flight most likely because of their compact size.
Once the design was increased to the size of the B-35 or B-49, any minor control issues that might have been overlooked by the smaller types were amplified by the increased size of the bombers.
By the time of the B-2, computers were able to compensate and allow for a stable and effective flight profile.

My guess is that had Horton been able to get an Ho.XIII built, he would have encountered the same problems that Northrop did with the B-35.

swampyankee said:

Flying wings had quite a long history in aviation; the Burgess-Dunne D.8 flew before WW1 (see Burgess Dunne | Historical Aircraft | Royal Canadian Air Force, for example) and its only stability problem was a tendency to weathercock, making crosswind landings difficult. It was well-known how to make a flying wing stable, although it was difficult to provide enough damping.

Studying the technology of a defeated enemy who had demonstrated some areas of technological superiority is standard practice. German technical superiority existed in some areas, including diesel (but not spark ignition) engines, many areas of ordnance[1] engineering, and many areas of chemical technology, and some areas of aerodynamics, but far from all[2].

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1: Ordnance vs ordinance. Using ordinance where ordnance is meant is one of the usage bêtes noire that most consistently annoys me.

2: I think it's difficult to argue that German airfoils were "better"; they clearly weren't as many German manufacturers consistently used NACA airfoils. Their engine cooling design wasn't particularly advanced; nobody did it better than had North American with the P-51. Their combat aircraft didn't have remarkably better (and largely worse) flight characteristics than those of the Allies nor did they have better aerodynamic efficiency.

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The Germans did use a lot of NACA air foils but they didn't use them exclusively. I think it was simply that Eastman Jacobs work at NACA was so outstanding and convenient to use that drove this rather than their own lack of ability to develop their own. They did

-All the Junkers aircraft had their own non NACA aerofoils.
-Focke Wulf often used NACA 5 digit
-Messerschmitt used NACA but elaborately modified, including
-BV-155 had laminar flow wing and so did apparently the Me 309.

The development of 'thick aerofoils' around 10% to 18% thick that made monoplanes possible came out of Hugo Junkers work on thick aerofoils for monoplanes (either that or the DVA at the University of Gottingen take credit.) Prior to the German work aerofoils were 5% thick and way to thin to be used in a monoplane without bracing. This is why late war German WW1 fighters such as the Fokker DVIII and others were so dangerous (due to the high climb rate)

The Go or Gottingen series of aerofoils were used in both Britain and the US. Shorts Sunderland, Shorts Sterling and Martin Clippers all used Gottingen Go aerofoils. (they were good for flying boats because of high coefficients of lift at low rotation angles) and the American Clark-Y was based on Gottingen.

However the NACA 4 and 5 digit were just outstanding but they were a rethink of the Gottingen aerofoils with a systematic way.

The NACA laminar flow work was also outstanding. But note the Japanese had a laminar flow technology and so did the Germans.

Note however although the Me 109 theoretically used an NACA air foil the Germans had developed a way of describing a modification to the aerofoils so the aerofoils looked quite different.

Both the Me 109 and Me 262 used NACA aerofoils but they were modified. The US actually used this modification system (eg on B-58 hustler).

Willy Messerschmitt's fame as an aerodynamicist actually rests on the outstanding pitching characteristics of the aerofoils he developed. His techniques were then applied to the modified NACA aerofoils. So they were NACA aerfoils in that they used the NACA polynomial algorithm to describe their shape but had the German modification system and were tested.

I think the main problem the Germans had was their engine development issues, fuel issues and the fact they struggled to introduce new designs or even alter old ones due to their assembly line issues, general pressure and bombing

According to wikipedia, interest in flying wings quickly died during the Cold War, because the required thick wings were in the way of supersonic speed?

Well, it was said that Gen Arnold thought the B-49 was not the wave of the future because everything would be supersonic and the thick wings would not allow the flying wings to go that fast. Of course we know now that supersonic speed is greatly overrated in most respects and still do not have or plan to have bombers that go supersonic over long distances. The B-2 has almost exactly the wingspan of the YB-49

MIflyer said:

Well, it was said that Gen Arnold thought the B-49 was not the wave of the future because everything would be supersonic and the thick wings would not allow the flying wings to go that fast. Of course we know now that supersonic speed is greatly overrated in most respects and still do not have or plan to have bombers that go supersonic over long distances. The B-2 has almost exactly the wingspan of the YB-49

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Arnold retired before even the YB-35 had it's first flight.
Hap retired in early 46., Died in early 1950.

He may not have been a big fan of the flying wings, but just how much influence do you think he'd have ?
He had 5 heart attacks , maybe more, between 1943-48.

Acheron said:

According to wikipedia, interest in flying wings quickly died during the Cold War, because the required thick wings were in the way of supersonic speed?

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Possibly, but there is a way around it:
1 Make the wing so big its thick enough.
2 Thicken or enlarge a central section into a lifting body like on the Horton Ho 229 or B2 Stealth Bomber.

A 'wee' story on the Horten Ho IV.




(November edition of Flypast by Chris Bryant - year?)

Acheron said:

According to wikipedia, interest in flying wings quickly died during the Cold War, because the required thick wings were in the way of supersonic speed?

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Armstrong Whitworth were very keen towards flying-wing passenger aircraft but after intensive research/surveys with prospective passengers they discovered none of them wanted to sit in a windowless environment.

I'm curious, Graeme, in that (rather funny) bit about the pilot "laying prone" in the Ho.IV - was it actually an Ho.IV?
The Ho.IV (aka Ho229/Go229) had a standard cockpit, where the pilot's posture was arranged in a conventional fashion.

GrauGeist said:

Ho.IV

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Horten H.IV - Wikipedia
The Horten H.IV was a German tailless flying wing glider in which the pilot was to lie in a prone position to reduce the frontal area, and hence drag.

Graeme said:

Armstrong Whitworth were very keen towards flying-wing passenger aircraft but after intensive research/surveys with prospective passengers they discovered none of them wanted to sit in a windowless environment.

View attachment 611140
View attachment 611141

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British flying wing practice seemed to like vertical fins and rudders on the wing tips. The Westland Hill Pterodactyl seems to have rudders on the lower surface of the wing and wing fences across the top.

UHD and 4K TV is impressive. It's very impressive on my wife's new notebook. It's perhaps possible passengers will accept a 8K monitor in lieu of windows. 8K TV now available commercially.

Milosh said:

Horten H.IV - Wikipedia
The Horten H.IV was a German tailless flying wing glider in which the pilot was to lie in a prone position to reduce the frontal area, and hence drag.

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Thanks for the wiki link.

It was late last night and my brain wasn't doing Roman math all that well.
.IV was coming across as .IX for some reason...

GrauGeist said:

Thanks for the wiki link.

It was late last night and my brain wasn't doing Roman math all that well.
.IV was coming across as .IX for some reason...

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That happens occasionally with me.