DB 603 vs Ju 213

[Tante Ju]

Thanks SR6. It looks like very complex foundry technique. I wonder if the blocks were molded in a single piece, or somehow welded together later, ie. from two halves?

What I also wonder is the weight of the block itself. I suppose its very light, suggesting that most of the weight is coming from moving parts (cyl. heads, reduction gears, camshaft etc.).

 

[tomo pauk]

I believe there was a question about exhaust thrust values of the 603A and 213A, and indeed the Jumo was faeturing some 20% more then the DB (open the picture in separate tab for hi-res):

 

[spicmart]

With the Jumo 213j offering 2700 PS and the DB 603N 2800 PS the greater exhaust thrust of the Jumo should compensate for the slightly less power output.
After the war there were Arsenal engine projects using 213 parts.
Was the DB 603 ever subject of any post-war development?

 

[tomo pauk]

...
After the war there were Arsenal engine projects using 213 parts.
Was the DB 603 ever subject of any post-war development?

I don't think so. Winning coutries (those with resources) have had their hi-power piston engines both in development and production, with jet engines either flying or in experimental phase. Cash-strapped French were trying to use as much of German gear they could scavenge, whether piston or jet engines, whole aircraft or tanks.

 

[spicmart]

Rolls Royce tested a Jumo 213 after the war. They obviously liked it (impressed?).

 

[tomo pauk]

Rolls Royce tested a Jumo 213 after the war. They obviously liked it (impressed?).

That's interesting. Do you have any details?

 

[stona]

Rolls Royce tested a Jumo 213 after the war. They obviously liked it (impressed?).

Roy Fedden wrote an article for Flight Global around the end of the war covering various German engine projects. This is what he wrote about the Jumo 213.

"The 213 J was the latest mark scheduled for production. The weight with intercooler was 2,325 lb., and the power 2,350 h.p. for take off on 87 octane fuel at 3,700 r.p.m. They seemed hopeful of quickly obtaining a production rating of 2,600 h.p. from the 213, and appeared willing to accept an abnormally high piston speed with high r.p.m."

That, I would suggest, is damning with faint praise.

Cheers

Steve

 

[Milosh]

Steve, what did R Fedden have to say about the Napier Sabre as it also had high rpm?

 

[stona]

Steve, what did R Fedden have to say about the Napier Sabre as it also had high rpm?

He was writing on his return from Germany, to where he had led a mission to investigate the state of German aero engine development at the end of the war on behalf of the Air Ministry, so his comments were about German engines. In fairness to the Jumo, Fedden conceded that

"...towards the end of the war, the Junkers 213 inverted V-12 liquid cooled type, rated at 2,200 h.p., was probably the best fighter piston-engine that Germany possessed."

He made the point that both world wars had been fought with

"inline or vee type liquid cooled engine, and the air cooled radial...with the exception that since 1918 designers have found how to make the radial cylinder arrangement work without whirling the whole engine around its crankshaft."

In his opinion

"The British, American, USSR, German and Japanese air forces all relied on these basic types for the war just ended, and the British Sabre stands out as the only breakaway to see considerable front-line operational service at high powers."

But, he doesn't make any technical observations about the Sabre, which, being an H-24, he saw as in a different class of engine to the inline or vee type liquid cooled, or radial engines on which he was commenting.

Cheers

Steve

 

[Robert Porter]

My ignorance is showing, what type of engine was the Sabre?

 

[stona]

Napier Sabre, a rather complex 24 cylinder liquid cooled engine which powered some British fighters like the Typhoon and Tempest.

It had a chequered development and history, but it was a powerful engine for the time (developing much more than the 1935 planned 2,000 h.p. by the 1944 version) and the issues were gradually overcome.

The Napier aero engine business, as Napier Aero Engines Ltd., became a subsidiary of Rolls Royce in 1962, its Eland engine may have something to do with that, and shortly thereafter the Napier identity was lost.

Cheers

Steve

 

[Robert Porter]

Okay, now I found it, so it was not an inline or a "V" it was four opposed banks. Now I understand the earlier reference thanks!

 

[tomo pauk]

Roy Fedden wrote an article for Flight Global around the end of the war covering various German engine projects. This is what he wrote about the Jumo 213.

"The 213 J was the latest mark scheduled for production. The weight with intercooler was 2,325 lb., and the power 2,350 h.p. for take off on 87 octane fuel at 3,700 r.p.m. They seemed hopeful of quickly obtaining a production rating of 2,600 h.p. from the 213, and appeared willing to accept an abnormally high piston speed with high r.p.m."

That, I would suggest, is damning with faint praise.

Cheers

Steve

Germans were also upping the RPM (and with it the piston speed) of the DB 603 line, with 603N, that was supposed to run on 3000 RPM. Quite the turning speed for the engine with stroke of 180 mm, and with it the piston speed. IMO the upping of the RPM with Jumo 213J, that was also a bit over-bored vs. earlier 213s, while receiving a 4 valves per cylinder head was quite en achievement, and within the current trend in Germany, while that trend was barely present in the West.
The world 'abnormaly' is hardly an engineeing term.

Steve, what did R Fedden have to say about the Napier Sabre as it also had high rpm?

The Sabre was with short stroke, 121 mm, vs. 165 mm for the Jumo 213. On same RPM operation, the Jumo 213 will reach greater piston speed, by some 1/3rd greater than the Sabre.

 

[stona]

"so it was not an inline or a "V" it was four opposed banks."

Napier engineer Frank Halford described it as a flat-H with liquid cooling and sleeve valves, which is about right

Maybe the difference in RPM between the Sabre and an engine like the Jumo 213 is that the Sabre was always intended to run at relatively high RPM whereas the Germans increased the RPM of the Jumo 213 above that originally intended in an effort to squeeze more power out of it.
Napier had experience of small cylinder engines in an H configuration dating back to the 16 cylinder Rapier and its development into the 24 cylinder Dagger, though both were air cooled.

Cheers

Steve

Edit: The Sabre cylinders were 5 x 4.75 inches, tomo has already made the relevant comment about the short stroke/piston speed.

 

[Robert Porter]

I remember a conversation I had with my grandfather about Piston stroke length. He said shorter stroke leads to higher RPM and more importantly higher heat generation and greater wear. It also required either more exaggerated lobes to drive valves or really tight gearing all of which also lead to higher heat and wear and shorter MTBF. But he mentioned military aviation engines had a very short working life in comparison to a typical car engine of the time. It was recognized that these engines would be frequently rebuilt or replaced over their operational life. Pushing an engine past its designed RPM limits typically resulted in timing issues and valve latency which usually resulted in a loss of performance and decreased reliability. Being an engineer for Pratt & Whitney he was fairly well acquainted with aircraft engines.

 

[tomo pauk]

"so it was not an inline or a "V" it was four opposed banks."

Napier engineer Frank Halford described it as a flat-H with liquid cooling and sleeve valves, which is about right

Hmm - two boxer engines in layout, one laying atop of another, both boxers driving the same reduction gear, same superchager and axcessories; neither upper nor lower bank were able to run separately.

Maybe the difference in RPM between the Sabre and an engine like the Jumo 213 is that the Sabre was always intended to run at relatively high RPM whereas the Germans increased the RPM of the Jumo 213 above that originally intended in an effort to squeeze more power out of it.
Napier had experience of small cylinder engines in an H configuration dating back to the 16 cylinder Rapier and its development into the 24 cylinder Dagger, though both were air cooled.
Cheers
Steve

Jumo 213 was designed for high RPM from the get go, since 211 was bound to hit the RPM limit very soon, and indeed a further increase of RPM was a way to increase power further. Another way of incresing the power was increase of compression ratio, as tried on the 213EB than needed C3 fuel to operate. Plus of course the application of ADI, intercooling etc.
The Sabre got increase of RPM to 4000 in late models, plus ADI.

 

[stona]

Jumo 213 was designed for high RPM from the get go, since 211 was bound to hit the RPM limit very soon, and indeed a further increase of RPM was a way to increase power further.

As far as I know the 213 was designed from the get go to run continuously at 3,000 r.p.m. The 213J was rated at 2,600 h.p. at 3,700 r.p.m. much above the original design speed.
Cheers
Steve

 

[tomo pauk]

As far as I know the 213 was designed from the get go to run continuously at 3,000 r.p.m. The 213J was rated at 2,600 h.p. at 3,700 r.p.m. much above the original design speed.

I'm not sure that do you mean by 'continuously' here. The 3250 rpm was limited to 30 min (1/2 hour) for the Jumo 213E (= late 1944). Even the 213A was turning 3250 rpm by early 1944.
It is very much possible that there was enough of stretch in the design for 3700 rpm for short term power (5 min?) especially once the 3-valve head (from 213A to 213EB) was superseeded with 4-valve one (213J).

 

[stona]

I have 3,000 rpm 'continuous' and 3,250 rpm 'take off' for the 213A, probably from Gunston or similar, hence the 3,000 rpm design parameter.

3,700 rpm was for the 213J (with the 4-valve head), but that's still fast for such a big engine, and way above the original design intention.

I can't find the originally intended speed for the Sabre anywhere, but I bet it was much higher than 3,000 rpm.

Cheers

Steve

 

[wuzak]

Hmm - two boxer engines in layout, one laying atop of another, both boxers driving the same reduction gear, same superchager and axcessories; neither upper nor lower bank were able to run separately.

Technically the Sabre was a pair of 180° V-12s mounted together on a common crankcase.

A "boxer" or "horizontally opposed" engine has the pistons on opposite banks moving in opposite directions - both were heading outwards or both were heading inwards at the same time (ie when one was going left, the other was going right).

A 12 cylinder boxer would require 12 crank throws and excessive length. Each piston would be connected to its own crank throw.

The Sabre's two cranks, on the other hand, were conventional 12 throw cranks as per normal V-12 usage. Pistons on opposite banks moved in the same direction - both left or both right.


It may be latter day usage, but engines such as the Sabre were still called in-lines, as were V-12s, even though their cylinders were not all in a line.

The Jumo 222 was described in British technical reviews as being a radialine - that is possessing features of both an in-line and a radial. That is there were several cylinders disposed radially around the crankshaft like a radial, while there were several cylinders (4) parallel to the crankshaft's axis.