Replace Me-109 with Me-155?

[Shortround6]

By 1945, DB 605 series was producing 2000 HP, and they still saw potential for ca. 2300 HP in immidiate future. Two stage superchargers were developed for them, which gave outstanding (better even than Griffon 65 for exampe, which was the best of operational Allied V-12 altitude engines) altitude performance. Sure it had potential.

Are we talking about "Luft '46" engines vs Allied 1944 service engines? Or Allied 1943 service engines?

BTW, Best Merlin Altitude Performance was from the 113/114 engines used in Mosquito 34s. 1440hp/3000rpm at 27,000ft using 18lbs boost or 1200hp/2850rpm at 30,000ft using 12lbs boost max continuous climb.

and for "Allied V-12 altitude engine" consider the engines in the P-38L. 1600hp WEP at 25,800ft no RAM and 1425hp at 26,600ft military (15 min) no RAM and 1100hp at 31,200ft max continuous ( no time limit) no ram.

What was the 605L rated at? take-off and emergency 1350hp at 31,400ft? Climb 1150hp at 31,400ft? max cruise 930hp at 31,000ft?

DB 605 figures are from an old "Jane's" and may be a bit off PS to HP conversion for one thing.

 

[Tante Ju]

Are we talking about "Luft '46" engines vs Allied 1944 service engines? Or Allied 1943 service engines?

We are talking about development potential of the late war DB 605 engines (supposedly exhausting its development capability), precisly the 605DC and 605L. There wasn't much Luft 1946 about them - the latter was cancelled in late 1944 because it was a backup, should the Ta 152 program fail for some reason, but supposedly, some still found their way into aircraft.

Your examples show the DB 605 had still a lot of potential in 1945. IMHO it was a viable engine, until the larger and heavier 603/213 series developed to a point where they produce MUCH more power than the lighter 605.

 

[Shortround6]

There is development potential and there is development potential.

A P&W engineer got a "B" series R-2800 up to 3800hp using 150in MAP and LOTS of ADI fluid on a test stand. Service "B" series R-2800s were not rated for over 2540hp WEP. "C" series R-2800s used different crankcases, crankshafts, connecting rods, pistons, cylinders, cylinder heads and every thing else except the bore and stroke. And they topped out at 2800hp in service.
How much development potential was there in the R-2800?

You were comparing prototype engines that never flew ( or at least were never in service aircraft) to engines that were in production and squadron use at the same time.

The History of aviation is littered with the stories of engines ( and aircraft) that were canceled "just as the bugs were worked out" and not just German ones. The number of failed American engines makes me suspicious of any claims of "future" potential.

 

[Tante Ju]

So, in your point of view, the 605 series did not have potential to increase power by 10-15% compared to current service ratings, ie. you say it would be impossible and/or unlikely? Because of what, exactly...? Any particular reason on your mind why DB could not pull off a planned development that occured in a similar timeframe between V-1650-7 and -9 series? (apart from the calandar showing April 1945 of course )

What would prevent running the 605L series at 1.75ata, the same boost as the service AM series but with a two stage supercharger and ADI as intercooler, ie. a different supercharger setting running at modest boost levels (ie. ca + 7 lbs) ? Some unknown issue with such powers at altitude - or roughly the same powers that were already achievable with NO2 injection in service?

Truth is, that the 605 series would somehow at the end of their development potential was a statement built on hot air. They did run into bearing problems in 1942-3, not forgetting they fixed those and then increased power output by 50% (ie. 1300 -> 2000 hp). Such claims about lack of potential are even more difficult to believe when one considers that DB was already running race db 601 series engines at 2700 HP in 1939, already proving the potential.

But then again, if you have any particular point (apart from generalisation) that would point towards the 605 exhausting its potential, I am curious to hear it.

Truth of the matter is, both the 109 / 605 could be further developed the same way as any other comparable plane was/could have been, but they represented a niche of lightweight, agile fighter-interceptor along the lines of Yaks, Spitfires - a niche that the RLM no longer wanted. What they wanted was one-pass bomber destroyer brutes, jets in particular, with heavier, sturdier airframes capable of carrying an armament best described as an overkill and absorbing punishment. None of the 152 series were particularly agile compared to the 109, but that wasn't on the wish list. IF fighters would have been such a major concern, the 109 would have a place, but they weren't, they were to be ignored. Since a.t.m. it was Messerschmitt who was producing jets, they would retire the Messerschmitt prop-job to concentrate on the Messerschmitt jet-job, kinda making the whole 605 series redundant, given that the aircraft using it would be no longer produced.

 

[DonL]

I think you are on a wrong way Tante Ju.

There are very serious issues, that the DB 605 could not be developed past 2000PS.

1. The DB 605 was linited to 2800 rpm max, no any normal engine or test engine (except the race engines) from all I have read, was ever past 2800rpm
2. The performance increase from 1475 PS to 2000PS was mainly through use of C3 and MW50 not through major design development.
3. The DB 605 was a "save" alloy engine built from inferior alloys then the Jumo 211 (as Bomber engine), the BMW 801, Jumo 213 and the DB 603.

Here had the Jumo 213 very big advantages because he got the same alloys then the Jumo 211, BMW 801 and DB 603 and could run at 3250 rpm and had a normal performance of 1750PS without C3 and MW50. Also to my understanding the DB design philosophy was rather different to the Jumo design, through their very light weight built, the DB engines were limited at their rpm output, and at some point of a design you can't only create more performance through rpm.

The weight difference between the Jumo 213 and the DB 605 was something about 150kg and that are to my opinion the better alloys and the more robust design for much higher rpm. So the Jumo 213 B-0 (test engine for C3) could create 2000PS with C3 but without MW50, with MW50 this engine would be at 2300PS, also the Jumo 213 could create a higher Kampf and Steigleistung then the DB 605.

Also the Jumo 213 was produced till the mid of the fifties for the french navy and could win an advertisement against the Bristol Hercules and Gnome-Rhône 14R engine for a air-sea rescue flying-boat. If the DB 605 would have had so much potential the french military would be interested and not only at the Junkers 213.

Also from LW manuals the Jumo 213 had a normal overhaul time of 170 hours compare to the 75-100 to the late DB 605.

I agree with Sh6 and the other Members that the DB 605 was at the end of his development, first through his light weight design and the inferior alloys.

 

[Gixxerman]

I think the term 'oil slinger' could refer to a type of device that flung oil onto the walls of its collection chamber either by centrifugal rotation or via a nozzle/spray, that would allow air bubbles to escape the oil easier hence quicker, perhaps, or something with an edge or change of angle upon a shaft that would help stop oil going where it isn't needed by flinging it off at that point - like stopping it before a bearing or trying to minimise flung oil being lost into the piston bores loosing some of it to ring creep by and burning..

Thanks for the reply.
I have a fair understanding of car especially motorcycle engines - the oil-cooled Suzuki Gsxr's - itself reputedly inspired by the RR/Packard Merlin's oil cooling - in particular (although I am a later w/c Gsxr convert).

If I was to use the parlance there, would I be correct as thinking of this as something like an oil gallery then, when oil is sprayed/pumped to the gallery to lose any aeration and then go on to the areas it's needed without any foaming?

I wonder if it was inspired by a look at the allied engines or just another case of engineers tackling similar problems coming up with similar solutions?

 

[Shortround6]

So, in your point of view, the 605 series did not have potential to increase power by 10-15% compared to current service ratings, ie. you say it would be impossible and/or unlikely? Because of what, exactly...? Any particular reason on your mind why DB could not pull off a planned development that occured in a similar timeframe between V-1650-7 and -9 series? (apart from the calandar showing April 1945 of course )

There are basically two ways to get from 2000hp to 2300hp (15% increase). One is to increase the rpm 15% And keep the boost the same ( assuming the supercharger can actually supply 15% more air. )
Problems with this is that a, the internal friction goes up with the square of the speed so a 15 increase in RPM causes about 32% more friction so you don't quite get 15% net horsepower gain (although the cooling load has gone up 15%). b, the stress on the reciprocating parts has gone up a similar 32% as well as stress on crankshaft and crankcase. Maybe they can stand it and maybe they can't or maybe they can stand it for a short while ( shorter time between overhauls?) If the strength was there to begin with the engine was probably over weight for 1475hp. DB 605 is already running at 2940fpm piston speed and very few successful engine ran faster ( Jumo 213 and Bristol Pegasus)Please note the weight jump from the 2400rpm DB 601 to the 2800rpm 605, not all is due to stronger parts I am sure but some is. This method does have the advantage of not requiring "super fuels" or at leas t not to the extent of method 2.

2nd way is to increase the boost, cram more air into the cylinder each time it fires. This is the way many engine designers went. It does increase the peak and average pressures inside the cylinder and can require stronger construction. (A bit more on that later). This one is very fuel dependent. If you don't have super fuels it doesn't work. 15% more than 1.98 AtA is 2.32 AtA to go from 2000hp to 2300hp. This pressure is possible, it was used by allied aircraft. Late war German fuel was close and might have permitted it. again this is net power, you do have to add in the power needed to drive the supercharger ot the higher boost/airflow. and the engine has to be strong enough to handle the total power made in the cylinders.

as far as the V-1650-7 and -9 series goes there was a lot more going on than just adding ADI. the -9 got stronger basic casting for the crankcase, it got the end to end oil crankshaft. Not only was oil distribution better but the elimination of oil holes and groves in plain bearings meant there was more net bearing area for the same sized bearings. The -9 engine was essentially a Merlin 100/110 and not just a Merlin 61/66 with ADI.

Maybe DB could have pulled it off. It depends on fuel, materials for the engine, lubrication and so on.

What would prevent running the 605L series at 1.75ata, the same boost as the service AM series but with a two stage supercharger and ADI as intercooler, ie. a different supercharger setting running at modest boost levels (ie. ca + 7 lbs) ? Some unknown issue with such powers at altitude - or roughly the same powers that were already achievable with NO2 injection in service?

The trouble with replacing N2O from a power output stand point is that the extra air (oxygen) that is supporting the higher power level is "free" from the engines stand point. The plane has to carry the weight and bulk of the N2O set up. Engines make two different powers that concern us, one is net power to the propeller or brake horsepower ( can be measured on a brake or dynamometer) the other is indicated horsepower ( also a number of names) but it is the power actually developed in the cylinders. The net or brake horsepower is what is left after you take out the friction, the pumps, and the power to drive the supercharger. The N2O system provides extra oxygen to burn without the engine having to pay (use) power to drive a supercharger to compress that much air. A second or auxiliary stage can take several hundred horsepower to run. One text book from WW II shows a "theoretical" supercharger of 65% efficiency needing about 175 hp to deliver 1200hp worth of air to it's outlet (intake of the next stage) at sea level pressure. the supercharger has also raised the temperature of the intake air from -48 degrees F to +200 degrees F. Now your inter cooler or ADI (or both) can help lower the temperature of the intake air, your second stage can boost the 1 AtA air to 1.8 rather easily but the total power needed in the cylinders may be 1575 hp for 1200hp to the prop. (100 for friction/pumps, 100 for the 2nd stage or engine supercharger and 175 hp for the 1st stage or auxiliary supercharger.
The use of N2O allows an engine of 1400hp or so in the cylinders to give 1200hp to the propeller.
The engine with the two stage supercharger has to be built strong enough to stand up to the total power developed in the cylinders. It can be done, it was done but it is not simple.

Such claims about lack of potential are even more difficult to believe when one considers that DB was already running race db 601 series engines at 2700 HP in 1939, already proving the potential.

It rather depends on the life of the engine ( most aircraft engines could be run at much higher than normal powers for short periods of time, experimenters got over 900hp from a 550-600hp P&W R-1340 Wasp engine in 1933/34 with 100 octane fuel)
and it depends on the fuel. I believe the race DB engine was running on a blend of fuel with a lot of alcohol ? It may show the engine won't instantly self destruct at such power levels and thus show "potential" but turning it into usable aircraft power may be another story. Alcohol needs less air per pound to burn on a Btu basis ( 1 pound of air will give more btus burning with alcohol than with gasoline), some alcohols are about equal to 114 octane for knock rating, and alcohol has a much high latent heat of vaporization than gasoline ( it sucks up more heat per pound of liquid) helping cool both the intake charge and the engine.
The R R type "R" racing engine was good for 2,783 hp (2,075 kW) at 3,400 rpm for "sprint" racing but R R never used the "potential" of this engine for a service engine or aircraft.

 

[davebender]

It's a matter of timing.

DB605D engine didn't enter production until fall 1944. Designing a new lightweight airframe to use the relatively lightweight DB605 engine isn't worth the trouble at such a late date. Ta-153 airframe was rejected for the same reason. Instead Focke-Wulf produced Fw-190D9 which was a relatively simple conversion of existing Fw-190A airframe.

 

[Jabberwocky]

Bottomline - even though the early 605 did not reach the robustness of for example, Jumo engines, it was quite sufficiently reliable even when introduced, even the first versions having a service life of 80-100 hours in practice. That's much better than early BMW 801s, or that achieved Napier Sabres achieved, like ever. The latter did not seem to last more than 20 hours even at the height of their "reliability" record.

That's how it may "seem" to you, but actual history is very different.

Napier Sabre TBO's evolved significantly through the war. Initial TBO's were 40 hours, but then dropped to 25 hours and then 20 hours as more engines came off the assembly line and Napier's quality control issues raised their head. However, with improved machinery and consulting from Bristol helping them come up with better sleeve alloys and nitriding techniques, TBO was about 75 hours by the end of 1943 and about 120 hours by the end of the war in Europe.

 

[Aozora]

It's a matter of timing.

DB605D engine didn't enter production until fall 1944. Designing a new lightweight airframe to use the relatively lightweight DB605 engine isn't worth the trouble at such a late date. Ta-153 airframe was rejected for the same reason. Instead Focke-Wulf produced Fw-190D9 which was a relatively simple conversion of existing Fw-190A airframe.

In other words there were no other aircraft, apart from the 109 110, which could use the 605. How many other projected or existing designs were slated to use the projected 605L series?

 

[davebender]

That's true during 1945 when German economy was collapsing and it's impossible to introduce any new piston engine airframe into mass production. Back up to 1942 (i.e. when Me-155 was designed) and there were a bunch of DB605 powered airframes which could have been placed into mass production.

 

[DonL]

no other aircraft, apart from the 109 110, which could use the 605

That's true during 1945 when German economy was collapsing and it's impossible to introduce any new piston engine airframe into mass production. Back up to 1942 (i.e. when Me-155 was designed) and there were a bunch of DB605 powered airframes which could have been placed into mass production.

Which?

The BV 155 was planed with a DB 603, as all new designs since 1942/43 were planed for the Jumo 213/DB 603!

The last serious new design was the Me 209 nothing else.

The only other fighter which was flying DB 605 was the Me 210C, and as we know with very inferior performance.

Next to this the He 111 was flying DB 601, Do 215 and FW 187. No other design to my knowledge.