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The He-178B Fighter Jet?

papacavy

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The Heinkel He-178 has always intriqued me and I often "fantasized" about a fighter varian with two 7.92mm machine guns in the wing roots (very few structural changes except a slightly improved engine.) This first variant, the He-178A Sperber would be a point-defense aircraft or, most likely, an advanced trainer. With a greatly improved and refined engine, the He-178B Sperber would be able to carry four machine guns (remember this is all speculative engineering). Then come the He.278 Falke with a JUMO axial flow engine and six 7.9mm machine guns and this one can be used over Britain and at the front-line, placing a jet fighter in active combat duty in 1941!

Let the speculation begin!

Remember, anything you submit may be used in a future alternate history novel, by me. Everyone will get lots of credit and if you have a German name, you may be used as a character.

Chuck
 

cluttonfred

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By the time an He-178 fighter variant could have flown, even multiple rifle-caliber machine guns were no longer an effective armament for a fighter, so I'd go with 2 x 20mm cannon as a minimum viable armament. Also, unless the speed could have been raised to well over 400 mph and preferably 450 mph then the slow acceleration of the early jets would have left it very vulnerable in anything but a very disciplined bouncing attack.
 

papacavy

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Thanks, Matt, for the input.

Would you care to elaborate on how you think Heinkel could turn the He-178 into a viable fighter? In my pending novel (not even an outline is written, yet) I will have Heinkel transfer the engineering work to Dipl. Ing. Matthias Lange!
 

royabulgaf

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The only way the 178 could operate over England is if the Germans captured the Isle of Wight. The 178 carried just enough fuel for testing, and those early jet engines were incredible gas hogs.
 

cluttonfred

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As royabulgaf said, the He-178 was simply a proof of concept design. It could have inspried a combat aircraft of the same general configuration, perhaps with the later HeS-6 engine. Per the Wikipedia entry on the HeS-3, "Work on a larger version, the HeS 6, started immediately, and was tested under a Heinkel He 111 late in 1939. While successful, notably in terms of vastly improved fuel economy, the weight was considered excessive and the design was abandoned in favour of the more advanced Heinkel HeS 8." It's not hard to imagine a crash program initiatied to bring the HeS-6 into production for combat aircraft scaled-up up, say 50% in weight from He-178, perhaps with large wing fuel tanks and a rocket-assisted takeoff. Performance over 400 mph might have been enought to make it work.
 

Michel Van

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the Heinkel He-178 needed major redesign for role as jet fighter

use of better Jet engine because the HeS 3 used hydrogen gas as fuel in prototype
Heinkel worked on HeS 3b that use diesel fuel (abandon in favor of HeS 8 in 1939)

with installment of MG in nose the HeS 3b has to move out center of fuselage further into back, to balance the aircraft.

It Biggest problems is the short range of 200 km and use of one Jet-Engine, if that fails the pilot sit in glider, wen is he lucky that engine not exploded.

so this aircraft would fit more effective in rolle had the Me 162 rocket interceptor.
 

Jemiba

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Michel Van said:
use of better Jet engine because the HeS 3 used hydrogen gas as fuel in prototype ..
Just to prevent misunderstandings: The prototype of the HeS 3 engine made its first ground tests
using hydrogen, not the He 178.
Could easily lead to claims, that Germany had built and flown the first hydrogen powered aircraft ... ;)
 

steelpillow

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If the HeS 3 had been developed to make it more powerful and more efficient, an HeS 3d could have powered an operational He-178 fighter. Some suggestions based on standard engineering practice:

* Improve combustion efficiency so that less fuel is wasted - adds range.
* Improve the compressor - adds thrust and also improves thermodynamic efficiency, increasing range.
* Improve the turbine - improves compressor performance, see above.
* Increase the combustion temperature - add both thrust and range. In particular, a secret new metal alloy would have made a huge difference - as it has done many times since.

Then, too, the plane could have been fitted with drop tanks, either a large central belly tank like the Spitfire or a pair of wing-mounted tanks like the Mustang.

Takeoff performance could have been enhanced with solid-fuelled rocket assistance.

At a pinch, a composite similar to the Mistel concept could have seen the He-178 carried aloft and released by a converted transport ot bomber. This might have been used for airframe development purposes while the engine programme was still in hand.

Had this happened, it could have been the first jet engine in operational service. What makes the scenario potentially convincing is that the HeS 3 had a radial compressor. This is theoretically less effective than an axial compressor, but is far easier to design and manufacture. While the other German companies developed axial-flow turbojets, these were notoriously temperamental. In Britain, Whittle and Halford developed radial-flow types which proved much more serviceable. Performance of an HeS 3d might not have been stellar, but it could have served as solid a foundation for a single-engined fighter as the Halford H-1, aka de Havilland Goblin, which powered the Vampire.

One other comment: the Jumo was not available for production until much later, and even then was not considered for single-engine use. Rather, successive improvements to the HeS 3 would have kept it ahead of the game. A larger, more powerful and heavily-armed replacement fighter would have been wanted - the rather wonderful Heinkel He 280 that, in real life, lost the political battle to the Me 262.
 

pathology_doc

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I know the Gloster E.28/39 (hope I got that right) was drafted with a token (and optional) gun armament, but it was never really considered as a viable fighter (although in its final form, it appears to have been faster than a Meteor I). My understanding is that for all that it was only the second jet aircraft, it was a far more sophisticated airplane all round.

For that reason, I'm not sure an He-178 fighter would have been a going thing. By the time you turn it into one (not just adding or finding space for guns and ammo but also providing sights, radio, pilot oxygen, more fuel - endurance is lousy - restressing the airframe, altering intake and exhaust geometry and rearranging internal space to suit the required bigger, more powerful engine, etc.) you've quite possibly got an altogether different airplane in every way (one could potentially end up with the He162 three or four years earlier, which might well be worth doing). Among other things, the -178 just doesn't have the required performance; in late 1939, piston engined fighters in front line service are already nipping at its heels and that's just the gunless bare-bones prototype. Putting military equipment on it is only going to make things worse, and then there's the issue with the poor service life of wartime German jet engines.

It's a bit like the argument that the British generals mishandled the use of tanks in World War One. Perhaps they did, but the Mark One tank was never the Blitzkrieg weapon that the Germans used to overrun the Continent in 1939-40, nor was it ever intended to be - they requested something that could overcome barbed wire and machine gun posts, and that was exactly what they got and exactly the use they put it to. When they tried to make it do things modern tanks would find easy, it failed dismally.

Likewise, if you want your First Jet Aircraft to be a fighter, you've got to specify your desire for development potential from the start, and space & weight have to be saved for all the things a fighter needs, with all that this implies for engine power available. A conversion unit of He-178 A-0 fighters is IMO only going to disenchant the front-line pilots, which is the last thing you want to do in real life, although admittedly it might serve the purposes of your plot quite well!!
 

shaba

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:)
just to show how small the 178 is this picture show a model the he380 at the same scale.The280 is actualy smaller than the me262
 

steelpillow

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Wing spans I found for some vaguely comparable small single-seaters:

He 178 7.2 m (23 ft 3 ins)
He 162A 7.20 m (23 ft 7 1/2 in)
Gloster E28/29 8.84 m (29 ft 0 in)
Polikarpov I-16 9 m (29 ft 6 in)
Boeing P-26 8.52 m (27 ft 11 1/2 ins)
Fokker Dr.I 7.20 m (23 ft 7 in)

So it looks marginal as an operational airframe, without significant redesign. Mind you, such redesigns have happened. And the He 162 went into production, though rather unwisely.
 

Jemiba

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pathology_doc said:
... For that reason, I'm not sure an He-178 fighter would have been a going thing.
In the FliegerRevueX 50 is a very informative article about the He 178, covering the development
of the engine and the aircraft. What is said there (and supported by other sources is, that the
He 178, purely a private venture by Heinkel, was strictly regarded as a testbed and "proof-of-concept-
demonstrator", as it would be called nowadays, for the then completely new jet propulsion. And
it was still used for this purpose, when the He 280 already was under development. So there
certainly never was a chance for a "He 178 fighter".
 

papacavy

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Very good stuff and much I haven't considered in the past.

So, the He-178 would never have been a fighter aircraft. Therefore, to continue this speculation, would anybody like to "design" an early single-engine, single-seat, point defense ("home defense" fighter/trainer) extrapolated from the He-178, or start from scratch?
 

Jemiba

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- The long jet pipe was already identified as a reason for a loss of thrust, so the He 178
derived design probably would have had a shorter one.
- The tail wheel landing gear wasn't really practical, so a nose wheel gear would have been
incorporated
- A newer a nd more powerful engine would be fitted.
- The fuselage and the wing and tail surfaces may remain largely unaltered.

... and so we hardly need a new design, we can simply look at the Junkers EF.123 ! ;)
( http://www.secretprojects.co.uk/forum/index.php/topic,8836.0.html )
 

steelpillow

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Then I thought to check the Folland Gnat. Wow! Here is my most recent post revised and turned on its head:

Wing spans I found for some vaguely comparable small single-seaters:

He 178 7.2 m (23 ft 3 ins)
He 162A 7.20 m (23 ft 7 1/2 in)
Folland Gnat 6.73 m (22 ft 1 in)
Fokker Dr.I 7.20 m (23 ft 7 in)
Gloster E28/29 8.84 m (29 ft 0 in)
Polikarpov I-16 9 m (29 ft 6 in)
Boeing P-26 8.52 m (27 ft 11 1/2 ins)

The He 162, Dr.1 and Gnat all went into production, with gun armament. On that basis the He 178 looks very do-able as an operational airframe, with no more than a bit of an upgrade.

Range would be the biggest problem unless it was given a more fundamental redesign with a larger airframe. Such makeovers have happened often enough, while earlier I suggested drop tanks.
 

pathology_doc

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Wingspan isn't everything; there's also the small problem of packaging the internals in such a way as to maintain centre-of-gravity within sane limits. Then there's the matter of providing an airframe that can withstand high-G combat stresses, building an airplane (and engine) that's easily serviceable and doesn't need wrapping in cotton wool...

Even before we get to that, you have to compare like with like. It's pointless to compare the He178 to the Dr.1 as the structure and propulsion of the two aircraft are like chalk and cheese (likewise, to a lesser extent, the Polikarpov). Comparison against the He162 fails because that aircraft positioned the engine outside the main fuselage, which probably did a lot to ease the internal packaging complications on the designers, and has a substantially different layout at the tail. The Folland Gnat is at least one generation more advanced again than the He162, with massive advances in engine construction and lessons learned in structure and layout, and it has swept wings to boot, which again makes a direct comparison quite inaccurate.

Finally, going on BSP:1935-1950, the E.28/39 - the only real direct comparison - appears to have been designed from the start, even as a test-bed, to take full advantage of the properties of gas turbine propulsion - it wasn't just the minimum acceptable airframe needed to get a jet engine into the sky. Then there's the matter of the British first jet being a tricycle as opposed to a taildragger, and so on.

Looking at the British single-engined jet fighters that either made their first flight during the war or arose out of wartime technology, the Vampire (first flown 1943) has a span of 40ft, while the Attacker (the work for which reached at least mock-up stage before war's end) is just under 37ft. On the other side of the Atlantic, the P-80's span is not less than 36 feet.

There are a lot of reasons why you can't look at a single dimension of a combat aircraft in isolation and exclaim that it will work this time because other aircraft with the same specific dimension have been enormous successes. You need to make your comparison across all three dimensions PLUS weight PLUS the aircraft planform PLUS the internal layout of the important aircraft systems (propulsion, fuel, armament, and later avionics where these start becoming a space-occupying issue), and where there are differences you need to admit them and justify them. Only then can you start to draw conclusions.
 

Jemiba

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To say it frankly: A fighter version of the He 178 would have had about the same relation to
the original aircraft, as the "Me 109R" (Me 209 V1) to the Me 109 series aircraft.
 

steelpillow

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What is a "variant" and what a "new design"? Sometimes quite limited improvements are given new designations, sometimes a single designation covers a whole raft of machines with barely recognisable commonality. For example the only real difference between late-model Spitifres and the Spiteful was the wing design. By contrast, the later Harriers kept the original name despite their new, larger wing.

So there are really two questions being asked:

- If we take the prototype He 178 airframe and HeS 3 engine, to what extent could they be productionised?

- If we take the He 178B designation, how far could we push its design and performance?

Naturally, they have different answers.
 

Arjen

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steelpillow said:
[...]
the only real difference between late-model Spitifres and the Spiteful was the wing design.
[...]
Actually the Spiteful had a new fuselage as well as a new wing. It looked like a Spitfire, but was a new design.

Other than that, I agree.
 

Jemiba

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The question about "variant" and "new design" probably is more tricky, than it
seems to be at first glance !
A "variant" to me is based on a former type, not only with regards to its shape,
but to its structure and components to a percentage of, say, 70 %. The latter
surely is debatable, but at about a commonality of around 20 %, we surely are
talking about the same engine, landing gear and avionics !

A "new design", well, was built starting with a clean sheet of paper, based on
experiences gained with older types, but not just on modified blueprints.

About the He 178: It was built using standard technology, so it surely could have
been built in numbers. But I think, those modifications, that would have given an
operational value to it, are hard to incorporate. The attached drawing is from
the Deutschen Museum, München via FliegerRevueX N° 50 and shows, that it was
quite a cramped design. A nosewheel landing gear was found to be necessary quite
early, but to my opinion wouldn't fit into this aircraft without really extensive changes.
The intake duct blocks the volume needed for the nose wheel and the engine
is located, where probably the main gear legs would be attached then.
Apart from the unfavorable long intake duct and jet pipe, the biggest fault to me is
the very limited internal volume, limiting the amount of fuel drastically.
A He 178B to my opinion, could have been an enlarged He 178, a lookalike but bigger
and so structurally a new aircraft. Such an aircraft, rectifying the faults of its ancestor,
could have been comparable to other single engine jets of that era. But it wouldn't have
been a real He 178 anymore.
 

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steelpillow

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Thank you, Jemiba, that is very instructive. The CG looks to be inline with the back of the main wheels, so one might manage to squeeze them just in front of the engine if a nosewheel were fitted. Who knows where Heinkel might have located it, perhaps it would have spurred them to split the intake the way de Havilland did. OTOH, several early jets had that long pipework fore and aft, some were more successful than others, so even if it were left in that does not guarantee failure.

Somebody mentioned the Attacker. This was still a taildragger. So even after the war, putting a taildragging jet into production was not unheard of. Heinkel might well have just shrugged his shoulders and accepted the compromise first time round, just as Supermarine did later.
 

pathology_doc

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I think the Attacker's compromise was due to time and the desire to make as rapid and easy use as possible of the Spiteful wing with a jet engine grafted on. Note that essentially all other British jets were nosewheel types. I don't think a tail-dragger would even have been contemplated if the work hadn't already been well under way before the war's end.
 

sienar

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Jemiba said:
The attached drawing is from the Deutschen Museum, München via FliegerRevueX N° 50 and shows, that it was
quite a cramped design.

Are there other primary source drawings of the 178 in that issue?
 

sienar

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"During the last months of 1937, Walter and Siegfried Guenther began with
predesign studies of the first jet-propelled aircraft (He-178) and specified a
static thrust of 1100 lb for the flight engine (He.S3). The aircraft was essentially
an experimental aircraft with some provisions for armament."

The above text is from the foreword by Hans von Ohain

Elements of Propulsion: Gas Turbines and Rockets

Jack D. Mattingly
 

pathology_doc

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sienar said:
The aircraft was essentially
an experimental aircraft with some provisions for armament."

This changes things. Is this on a basis of "fitted for but not with" (squadron armourer level fit-out, with firing circuits in place and the guns requiring only to be slotted into spaces) or "space and weight reserved" (factory fit or minor redesign/batch number fit-out, with plumbing and/or wiring required)? I'm assuming between two and four MG17 or similar.
 
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