WesWorld

Diesels shouldn't be a problem with regards to speed. You just need enough power.

I saw a really nice H-4 whiff the other day with four turbofans. Looks so much cleaner without the props and nacelles.

Then I have to find were Diesels with enough power are manufactured, Or made a W-style engine welding two smaller diesels together.

Contact Junkers Jumo for information on their line of diesel aircraft engines, commonly in use in various parts of the world.

[Historical Jumo-205 & -206 models, and ahistorical Jumo-208 models are available, the -208 is a 1500 hp diesel radial used in Germany on a number of transports and on seaplanes. The -209, a 3000 hp two-row radial, is under development, but it will be several years before it's ready, not enough market interest yet to push it to completion.]

I'm curious, but 1500hp seems like a lot from a 9 cylinder radial engine even with a bit higher specific power from a diesel.

If Poland wants more power, they need Isotta-Fraschini's new Asso 2000D engine which'll put out around 1800-1900hp with very good reliability. It's a diesel conversion of the existing and highly successful Asso 1500. (This engine is still in production today, although with lots of turbochargers and intercoolers for high speed marine applications)

The Jumo-208 essentially a straight scale-up of the Jumo-205D, which got 880 hp out of only 16.7 liters displacement. The Jumo-208, on the other hand, is a 27.5 liter engine.

For this plane to work a 2500-3000hp engine is required.

There aren't any of those just yet that I'm aware of. Jumo is working on the Jumo-222 and the Jumo-209, both of which will be in that range, but neither' will be ready for a bit. DB is working on the DB-603, the -604, and the DB-609's being sketched out (without the He-119 and with the He-177 not being tasked with dive bombing, DB hasn't worked on the -606 or -610). Argus hasn't started any work on the big H-blocks yet, though it has gotten the As-412 up and running (though with cooling problems). BMW is working on the BMW-802 and the -803, but neither will be ready for several years.

P&W is collaborating with Jumo on the Jumo-209 (in the US, it will be the RD-3300), while also working on the R-4360. Wright has the R-3350 running, but it needs a little more development before it's producible, wihle the R-2160's being developed. Allison has the V-3420 coupled engine, which could work for you, I suppose.

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The Jumo-208 essentially a straight scale-up of the Jumo-205D, which got 880 hp out of only 16.7 liters displacement. The Jumo-208, on the other hand, is a 27.5 liter engine.

I thought the 208 was a radial engine? Two stroke scavenged radial is going to be hellishly complicated, even more so when you add another row. You've got to bear in mind the increased cooling demands for the air cooled radial as well which'll lower power. 1500hp is a lot of heat to get rid of from 9 cylinders (about 50% more than petrol 9cyl radials) with arguably less cooling surface. You can't put as many thin fins on the cylinders as they need to be thick and strong to withstand the higher combustion pressures of the diesel.

How does Germany afford to develop all those engines?

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Wright has the R-3350 running, but it needs a little more development before it's producible

Well, its still unreliable even in 1945. By unreliable should actually say likely to spontaneously combust.

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For this plane to work a 2500-3000hp engine is required.

Bristol Centaurus or Rolls-Royce Vulture eventually. Alfa-Romeo 1101 or Isotta-Fraschini V1716D in a few years.

So as of now the DB-610 is the best bet?

Diesel can be water cooled and four stroke.
I still think diesel is the best bet for giving the plane the required range.

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Originally posted by Marek Gutkowski
So as of now the DB-610 is the best bet?

Diesel can be water cooled and four stroke.
I still think diesel is the best bet for giving the plane the required range.

The DB610 doesn't exist here. 5000nm range doesn't have to be diesels, look at the various large Soviet bombers after WWII. They're going further than that with large petrol engines.

Personally I doubt the cost of developing the plane is ever going to pay back whatever passengers want to go from Poland to Russia/China. Air travel is pretty expensive.

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Originally posted by Red Admiral
The DB610 doesn't exist here. 5000nm range doesn't have to be diesels, look at the various large Soviet bombers after WWII. They're going further than that with large petrol engines.

Personally I doubt the cost of developing the plane is ever going to pay back whatever passengers want to go from Poland to Russia/China. Air travel is pretty expensive.

Not yet but it will.
I have the DB-605 development from Hrolf, welding two together is not a leap in logic.Diesel is not the only answer for the problem but it is the best, less fuel too carry the more room for cargo.

I already know this will not be a commercial success. Exports will be a problem as most of You will chose one of the RL designs like the Lochheed Constellation or Bristol Britannia or Boeing Stratocruiser.

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Originally posted by Red Admiral

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The Jumo-208 essentially a straight scale-up of the Jumo-205D, which got 880 hp out of only 16.7 liters displacement. The Jumo-208, on the other hand, is a 27.5 liter engine.

I thought the 208 was a radial engine? Two stroke scavenged radial is going to be hellishly complicated, even more so when you add another row. You've got to bear in mind the increased cooling demands for the air cooled radial as well which'll lower power. 1500hp is a lot of heat to get rid of from 9 cylinders (about 50% more than petrol 9cyl radials) with arguably less cooling surface. You can't put as many thin fins on the cylinders as they need to be thick and strong to withstand the higher combustion pressures of the diesel.

How does Germany afford to develop all those engines?

My error in phrasing: the power of the Jumo-208 is a straight scale-up of the Jumo-205D, the design is not, as previously stated it's a 9 cylinder radial. The R-1820-86 didn't have a problem with cooling. at about the same horsepower. There were other 2-stroke radials during the period, including two-row Clergets, the big Nordbergs, etc, so the problem was historically not a problem. Also, on the power issue, the historical Jumo-208 was a 25.5 liter engine developing 1475 hp, so a 27.5 liter engine developing 1500 hp shouldn't be a problem.

As to how are all these engines being developed, they were historically (and more, DB had a lot more projects historically than it has in WW). The other thing to keep in mind is that German manufacturers have more export orders than historical.

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Wright has the R-3350 running, but it needs a little more development before it's producible

Well, its still unreliable even in 1945. By unreliable should actually say likely to spontaneously combust.

Should be a bit better here, with less pressure to get a long-range bomber out the door, but as I said it's not yet ready for service.

British engines likely to fit the bill;

The Bristol Hercules XXI currently rated at 1,650hp. The XXII of 1943 will have 1,770hp. both are civilian marks of military Hercules radials.

Bristol Centaurus VI 2,585hp in 1944 (but by no means the most powerful of the series).

Sabres and Vultures being liquid-cooled engines probably aren't servicable enough to run on airliners nor fuel efficent enough.

Napier-Paxman's line of diesel engines will have the Pilates III rated at 1,650hp in 1939 and the monstrous Prometheus I rated at 3,580hp for 1943 (24-cyl X layout).

I never expected this number of engine proposals.

I have a deal with Adm.K for a joint project for an engine.
Same deal I have with Hrolf. Poland provides the currency Russia the Know-how with the person of A. Charomskiy.

Still it being a commercial design all types of engines are a possibility.

I never really understood how the civilian Hercules engines came to be the most powerful of the series. The last versions putting out around 2100hp. Similar to the Centaurus, though they were getting up to 3500hours between overalls in the end. One of the engines was tested up to 3500hp as well. A way off yet though, especially the reliability.

I'm not sure why the liquid cooled engines would be less reliable or less fuel efficient, they should be better in both regards. Well it'll take a few years more development to get the reliability, but thats the same as for the Centaurus or Hercules.

Historically inline engines never made it as airliner engines. I can't think of many (any) airliners with inlines other than the Avro Tudor (York too but that was a military type and used the Lanc wing and engines to save time). There was a Canadair DC-6 with Merlins but that wasn't too popular either.

I guess the radiators and associated systems require extra servicing whereas a radial is pretty straightforward.

I know what you mean about the Hercules but it seems it took until the mid/ late 40s to get that kind of power, perhaps using lessons from Centaurus. It puzzled me why Bristol by 1949 had two similar rated radials. In WW the civil and military Hercules have identical ratings.

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Originally posted by Hood
Historically inline engines never made it as airliner engines. I can't think of many (any) airliners with inlines ...

Remember the 1930s de Havilland airliners (Albatross, Dragon, Dragon Rapide, Express, etc) had Gipsy variants.

Not the super-long-haul airliners, but they did have inlines.

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Historically inline engines never made it as airliner engines.

That's because the US was by far the biggest market for air travel, and US companies didn't make any good enough inline engines. It's nothing to do with the relative merits of the engines, simply protectionism.

The radiator doesn't add that much complexity, but gives better cooling, leading to improved performance and reliability in addition to reduced drag.

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It puzzled me why Bristol by 1949 had two similar rated radials.

? The Hercules was 2080hp and the Centaurus 3220hp with quite a difference in size and weight.

Viking, Brabazon, Bristol Freighter, Languedoc, Bv44, Fw200, Fw300, Il-14, Scandia, Ambassador, Hermes/ Hastings, YaK-16, Breguet 763 Provence, Miles Herald (first prototype) and De Havilland Flamingo II. Those are just the post-war non-US radial-engined airliners I can think of off the top of my head. The HP.42, A.W. Ensign are two British pre-war radial powered airliners. I can't think of many other large pre-war inline powered airliners other than the DH Dragon series.

I'm not counting smaller feederliners like the Dove or other airliners powered by Gipsy series engines as I'm talking about 1,000hp + V-12 inlines.

The Hercules though had the better postwar commerical use than the Centaurus.

There are many other issues at work in design choice, e.g. really surprising that Bristol used Bristol engines on it's designs. The thing is there's no actual evidence giving the air cooled radial an edge in reliability. I've seen quite a bit in favour of the liquid cooled engine.