Horton HO 229 Vs Vampire...

Juha said:

Yes, but the Project Proposal IV was that which became the production version of the Me 262 not one of those paper proposals

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Well if you make enough suggestions you might get lucky with one. Messerschmitt got lucky when Hitler decided that he wanted a fighter bomber. Milch's response to Hitler berating him in April 1944 about the lack of such an aircraft was, apparently (Foreman/Harvey), "My Fuhrer, the Me 262 was designed as a fighter in the first instance." This despite work on the fighter bomber variant being prioritised at Messerschmitt in December 1943.
Cheers
Steve

stona said:

Well if you make enough suggestions you might get lucky with one. Messerschmitt got lucky when Hitler decided that he wanted a fighter bomber. Milch's response to Hitler berating him in April 1944 about the lack of such an aircraft was, apparently (Foreman/Harvey), "My Fuhrer, the Me 262 was designed as a fighter in the first instance." This despite work on the fighter bomber variant being prioritised at Messerschmitt in December 1943.
Cheers
Steve

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It had nothing to do with luck or Hitler's whims, its was a normal upgrading of plans in light of flight testing and because of orderer's (RLM) more define/changing demands. In fact Hitler's demand revealed the embrassing fact that Messerschmitt had promised something that wasn't adequately worked out and the adding of bombs was found out to be clearly more difficult than Messerschmitt A.G. had thought. But the difficulties surprised also Milch and others in RLM's top hierarcy. Or more exactly the way how the bombs were to be carried was worked out but not the way they affected plane's handling.

Edit, reply to Koopernic moved to:
http://www.ww2aircraft.net/forum/av...compressors-ww2-jets-39511-4.html#post1199931

Juha said:

It had nothing to do with luck or Hitler's whims,

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Whim? That's one definition of a 'Fuhrerbefehl'.
Cheers
Steve

stona said:

When in 1944? Before the prototype(s) even flew?

On 10th December 1942 Milch accorded the highest priority (code 'Vulkan') to the Me 262 with no mention of a bomber role. Throughout the same month Messerschmitt wrote on several occasions to Georg Pasewaldt, Chief of Development in the Technical Office of the RLM, with all sorts of problems that needed to be solved before the type could enter production. Included was the requirement for armament and other equipment to be brought up to 'current standards', yet again no mention of bombing. If Messerschmitt did suggest the role, it was unofficially.

In April 1944 some of the first two batches of Me 262s completed were delivered to Erprobungskommando 262 and it was at this time that Hitler discovered that none were equipped with bomb racks. At this time it seems Messerschmitt were working on ways of converting the Me 262 to carry bombs, but that is nearly two years after the first prototype flew in July 1942.

Cheers

Steve

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Memorandum to the RLM dated 13th September of 1942 signed Willy Messerschmitt.

Willy proposed adapting the aircraft to the bomber role.

Source; Die Illusion der Wunderwaffen, ISBN 978-3-486-55965-1

Ha. When I put"Fuhrerbefehl" into a translator, it comes out "Drove printer command!" And computers weren't even in general use at the time!

Well, they DID have the abbacus and the Enigma machine ... no, wait, we captured one of those ... or someone did, probably on U571? Ha, ha ... for those of you who don't get American humor, that's a joke.

We all know the Germans bombed Pearl Harbor, blamed it on the Japanese, and then started dumping Volkswaggen dealerships all over the country to subvert the U.S. economy, don't we?

Uh ... that was a joke, too ... no takers, so I suppose it wasn't funny.

stona said:

Whim? That's one definition of a 'Fuhrerbefehl'.
Cheers
Steve

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IMHO a whim is a fairly accurate way to describe the May 44 Führerbefehl. That doesn't mean that I see all or most of the Führerbefehle as whims.

Juha

I always thought the vampire had terrible handling compared to the horten ho 229. Shouldn't the horten ho 229 have better handling due to the lack of a tail?

DerGiLLster said:

Shouldn't the horten ho 229 have better handling due to the lack of a tail?

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Not necessarily! There's a reason why most aircraft at the time, and now, have both a vertical fin and horizontal stabilisers on the tail. It's the most simple solution to a very complex problem. Even Lippish's Me 163had a vertical fin and rudder, unlike some of the gliders from which he had developed it. Turning a 'flying wing' can be very difficult to do without some unpleasant aerodynamic characteristics of this type causing some malicious handling.
Cheers
Steve

DerGiLLster said:

I always thought the vampire had terrible handling compared to the horten ho 229. Shouldn't the horten ho 229 have better handling due to the lack of a tail?

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Did the Vampire have terrible handling ?
Most things I have read describe it as easy and a joy to fly, and as it was used to trial carrier landings for jets surely it can't have been that bad ?

Early models had problems with snaking which seems to have been a common problem with 1st generation jets. Later models got bigger tail fins which might have been a cure for the snaking.

DerGiLLster said:

I always thought the vampire had terrible handling compared to the horten ho 229. Shouldn't the horten ho 229 have better handling due to the lack of a tail?

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Not if you look at the results of the DeH 108, whose uncontrollable oscillations killed one test pilot, and would have killed a second if he'd been taller, which was why the idea was abandoned.

All three DH 108s crashed killing all three pilots. Maybe that's why the British decided tailless aircraft might be something they could do without for the time being.
Cheers
Steve

DerGiLLster said:

I always thought the vampire had terrible handling compared to the horten ho 229. Shouldn't the horten ho 229 have better handling due to the lack of a tail?

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Do you have a source for that? I know people who have flown vampires and they say quite the opposite.

Perhaps pointing out that the B-2 had decent handling because modern technologies addressed the problems of tailless flight doesn't apply

GrauGeist said:

Perhaps pointing out that the B-2 had decent handling because modern technologies addressed the problems of tailless flight doesn't apply

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It was solved long before that. Think of the Vulcan bomber, though like the Me 163, still a vertical fin.

Cheers

Steve

The Vulcan (and B-58, space shuttle, etc) are more akin to the DFS194 and Me163 as the B-2 was to the HoIX, YB-35 and YB-49 types.

GrauGeist said:

The Vulcan (and B-58, space shuttle, etc) are more akin to the DFS194 and Me163 as the B-2 was to the HoIX, YB-35 and YB-49 types.

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Yes, but they are tailless aircraft

They overcame many of the aerodynamic problems of the type. They did retain a fin, an eminently sensible compromise as Lippisch had discovered years earlier.

Cheers

Steve

And back to my point regarding the B-2, which is a true flying wing...it's stability and performance is possible today because it's design is a refined result of modern engineering and it's avionics is computer assisted, making for optimum performance, where the YB-35 and YB-49 weren't afforded that luxury.

Of course, the HoIX was also without benefit of modern technology, as well.

stona said:

All three DH 108s crashed killing all three pilots. Maybe that's why the British decided tailless aircraft might be something they could do without for the time being.
Cheers
Steve

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The DeHaviland DH108 might be the source of the myth that tailless designs can't go supersonic or transonic. The fact that the Me 162 was the fastest aircraft of the war and suffered less Mach tuck than most other aircraft with conventional tails and perhaps even the Me 262 should dismiss that idea.

If fact tailless designs were of great interest to early transonic jet designers since the lack of a tail meant the effects of shock impingement of the wing on the tail was eliminated.

The crash of all three DH108 seems to have had nothing to do with their tailless design.

The DH108 had been designed as a test bed for proposed tailless versions of the comet airliner and used the stubby flat nose of that companies Vampire jet, a Mach 0.75 aircraft. When the comet went for a conventional layout the DH108 was 'misused' for supersonic research. It's a case of adapting a design for a new purpose it had not been originally considered for, of forcing a square peg into a round hole.

As the aircraft approached the speed of sound the relatively blunt nose experienced a dramatic increase in pressure and pitched the nose up in what was described as a shock stall. Worse, aerodynamic forces were transmitted back from the elevons to the joystick and a severe type of vibration called PCO pilot couple oscillation set in. The whole sequence was so severe it seems to have Brocken DeHaviland's neck before the aircraft pitched up and broke its wing spars.

Eric Brown experienced the same problem but says that as he was shorter he didn't hit his head on the canopy AS DeHaviland likely did.

The solution was to fit a pointy nose from late model vampires and to use fully hydraulic irreversible controls rather than power boosted controls.

Despite the lack of supersonic wind tunnels in Britain compared to Germany and the capture of German data the evolution of the DH108 the genesis of the DH108 as a comet test bed seems to have lead to this somewhat predicable outcome. There was plenty of data from large calibre naval guns in Britain, the German V2 missile had been modelled on an artillery shell, the German Mauser M1898 rifle had had its bullet changed from round tipped to pointy and created the 'spitzer' bullet. The Miles M52 didn't have a blunt nose, nor did the Bell X1.

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There is only a little truth to the tailless claim. Wings have pressure distribution: much of the upper surface of a wing has a lower pressure than ambient and much of the lower a higher pressure. This generates a wings lift and also its lift distribution (ie pitching moment). As the wing approaches the speed of sound the behaviour of the air becomes non linear, compressible and so the centre of lift moves aft to the shock wave. The aircraft is now nose heavy an may not be able to pull out of a dive. P-38 and P-47's could end up in death dives. The improvised solution was to introduce dive recovery flaps under the leading edges to pitch the wing up.

Modern aircraft use wing sections which don't change their pitching moment much. The wings are thinner and the thickest portion of the wing is already at 50% rather than 20%. Electronics does the rest, simply automatically trimming out the change in pitch.

In theory a tailless design doesn't have as much tail moment arm but in practice if the right airfoil is used and there is sufficient sweep tailless designs work fine. The deltas such as the F101/106, Mirage, Fairey Delta etc work fine.

The Vought Cutlass was a tailless supersonic design, Americas first supersonic, after burner equipped, missile carrying fighter was tailless. It had problems but they came from the under powered engines and systems.

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Some tailless deigns used an auto stable air foil, the Fauvel flying planks for instance. The Northrop designs did not, they used wing sweep, wing twist so that the wing tips were positioned to perform the function of a tail. Northrop also added slats to improve the pitching moment.

The Me 163 used an bit of both, wing sweep and an auto stable air foil as well as slots (similar to slats).

The Horton Ho 229 used an auto stable air foil on the bat like tail but not on the wings. All of the Horton designs handelled well except for one they made using a laminar flow air foil.

These reflexes and wing twists if severe enough can cause shock wave problems but if the sweep is enough they can be moderate.