Me410 effective as a light bomber?

[kool kitty89]

That hammers home one thing - a timely 2-stage DB 605 would've been a major boon for the Axis, at least on short term.

Puting the DB-603 supercharger on the DB-605 from the start (ie starting production with both A and AS models in parallel) in 1943 would have been a big enough deal on its own. Or even considering larger/high alt supercharging on the late model 601s. That's probably more important than intercooling, water injection, or 2-stage developments.

 

[tomo pauk]

Big supercharger really boosted the performance of the DB 605 line, bringing the hi-alt power to the level of 2-stage Merlin (though the 70 series was still the king of hi-alt). The MW-50 helped with low- and mid-alt power since it allowed for much increased boost. The inter-cooler, with or without conjunction with MW 50, would also come in handy.

In a thread that was here some months ago, I've suggested using the DB-601E as a basis for new engines with following improvements (some can be used together, some cannot): big supercharger from DB 603A (for 1943), intercooler (for late 1942), 2-stage S/C (late 1943), increase in RPM to 2800 (like the 601N and eventually 605; in 1943), MW 50 (winter of 1943/44).

The S/C of the 601E was 260mm diameter, 75% efficient, 363 m/s tip sped; for 603A respective values were: 295mm, 77% and 378 m/s.

 

[Denniss]

Problem wit the DB 601E was either its use of expensive bearings (of which germany had a shortage) or internal construction details prevented them from using much higher boost. May have also been a combination of both.
AFAIR 2800 rpm were already possible above critical alt.
And yes, DB should have tried much earlier to put a larger diameter supercharger on 605 to create an experimental high alt engine and present it to the Luftwaffe and RLM guys. They would then have Bf 109G-6/G-14 for the East Front and G-6/AS and G-14/AS for the West Front. This would then face the allies with Bf 109s at a similar power level compared to their P-51s.

 

[tomo pauk]

Denniss - care to elaborate a bit on those intricaties of the DB 601E?

On topic: original data for the Me-410: link.

 

[kool kitty89]

Big supercharger really boosted the performance of the DB 605 line, bringing the hi-alt power to the level of 2-stage Merlin (though the 70 series was still the king of hi-alt). The MW-50 helped with low- and mid-alt power since it allowed for much increased boost. The inter-cooler, with or without conjunction with MW 50, would also come in handy.

Given the mustangs were mostly powered by Merlin 61 and somewhat lower alt optimized 66 equivalents, the performance of the 70 series isn't quite as relevant ... or at least necessary to match/beat. (and the fact the Mustang featured a mix of engines like that points to the better high alt performance envelope of the 61 still not being worthwhile enough to sacrifice power down low)

In a thread that was here some months ago, I've suggested using the DB-601E as a basis for new engines with following improvements (some can be used together, some cannot): big supercharger from DB 603A (for 1943), intercooler (for late 1942), 2-stage S/C (late 1943), increase in RPM to 2800 (like the 601N and eventually 605; in 1943), MW 50 (winter of 1943/44).

The S/C of the 601E was 260mm diameter, 75% efficient, 363 m/s tip sped; for 603A respective values were: 295mm, 77% and 378 m/s.

If nothing else, they should have been experimenting with larger/higher alt optimized supercharger arrangements on the 601 line itself, before the transition to the 605. (higher alt tuned 211s would have been useful too, but given most applications it was adopted for, there's less express incentive for that over focusing on the 213 ... compared to say, if something like the Fw 187 had adopted the 211)

 

[tomo pauk]

Given the mustangs were mostly powered by Merlin 61 and somewhat lower alt optimized 66 equivalents, the performance of the 70 series isn't quite as relevant ... or at least necessary to match/beat. (and the fact the Mustang featured a mix of engines like that points to the better high alt performance envelope of the 61 still not being worthwhile enough to sacrifice power down low)

I'd say those were equivalents of Merlin 66 and Merlin 63, not 61 Merlin 70's series were installed in a number of Spitfires and Mosquitoes.

If nothing else, they should have been experimenting with larger/higher alt optimized supercharger arrangements on the 601 line itself, before the transition to the 605. (higher alt tuned 211s would have been useful too, but given most applications it was adopted for, there's less express incentive for that over focusing on the 213 ... compared to say, if something like the Fw 187 had adopted the 211)

The sooner Jumo gets the 213 in production, the better chances are for the LW pilots in 1944 (of course, bolt the 213s on the Fw 190s). With fully working BMW 801D, DB 605A/603A and availablity of Jumo 213A from late 1943 on, there is no much appeal on the 'fighter version' of the Jumo 211.

 

[Milosh]

Given the mustangs were mostly powered by Merlin 61 and somewhat lower alt optimized 66 equivalents, the performance of the 70 series isn't quite as relevant ... or at least necessary to match/beat. (and the fact the Mustang featured a mix of engines like that points to the better high alt performance envelope of the 61 still not being worthwhile enough to sacrifice power down low)

The P-51B/Cs were almost equally split between the V-1650-3 (1950) and V-1650-7 (1790) engines.
With the introduction of the P-51C-5-NT onto the Dallas production line and the P-51B-15-NA in the Inglewood production line, the Packard V-1560-7 engine was adopted as standard.

All P-51D/Ks used the V-1650-7 (9600) engine.

 

[kool kitty89]

The sooner Jumo gets the 213 in production, the better chances are for the LW pilots in 1944 (of course, bolt the 213s on the Fw 190s). With fully working BMW 801D, DB 605A/603A and availablity of Jumo 213A from late 1943 on, there is no much appeal on the 'fighter version' of the Jumo 211.

211 seems like it was always a supplemental engine ... not the best in any class, but produced in large numbers and more reliable and easier to maintain at times. But yes ... bombers, transports and other aircraft that don't need the likes of the 801 would make the most sense there. (4-engine bombers using 211s would have been useful ... had they been developed -the few 4-engine heavy bomber/transport aircraft that did appear were a bit too large for the 211 to work on ... and lack of a more modern replacement for 2/3 engine transports like the Ju-52 -I wonder if the He-111 would have handled reasonably well adapted into the dedicated transport role)

The P-51B/Cs were almost equally split between the V-1650-3 (1950) and V-1650-7 (1790) engines.
With the introduction of the P-51C-5-NT onto the Dallas production line and the P-51B-15-NA in the Inglewood production line, the Packard V-1560-7 engine was adopted as standard.

All P-51D/Ks used the V-1650-7 (9600) engine.

It's the 1650-3 powered aircraft that showed the more noticeable high-alt performance edge over the contemporary 190As or DB-605AS/ASM (or DB-603A). The 1650-7 powered Mustangs would be tuned more into the optimal performance range of the existing German designs, if not a bit lower in the case of the 605 AS and Jumo 213.

 

[GregP]

The P-51's needed to be tuned to the actual bombing altitude of the 1,000-plane raids, not the Luftwaffe's top fighters. Their job as escort was to protect the bombers, not get higher than the highest German fighters. If the Luftwaffe was diving through the formation, they were already higher and enough P-51's had to STAY with the bombers so they would not be abandoned to what German fighters were left.

The -3 or -7 didn't matter much to the mission, just to individual fighter vs. fighter situations.

The -7 P-51D could get to over 41,000 feet, and if they had a "high cover" force, it had 500+ miles to get that high at cruise speed and, if there WAS a need and a mission element for P-51D's to get way up high, then they were probably there when they needed to be there. Any combat at 35,000+ feet in WWII was a 2.8 - 3.1 g thing that went downhill very fast. There were no hard breaks or the hard-breaking pilot would stall and fall several miles before recovering. About all they could do was to make gentle turns or a roll and dive. They surely weren't doing much climbing fighting, Lufbrey circling, or "dogfighting" at those altitudes.

 

[kool kitty89]

The -7 P-51D could get to over 41,000 feet, and if they had a "high cover" force, it had 500+ miles to get that high at cruise speed and, if there WAS a need and a mission element for P-51D's to get way up high, then they were probably there when they needed to be there. Any combat at 35,000+ feet in WWII was a 2.8 - 3.1 g thing that went downhill very fast. There were no hard breaks or the hard-breaking pilot would stall and fall several miles before recovering. About all they could do was to make gentle turns or a roll and dive. They surely weren't doing much climbing fighting, Lufbrey circling, or "dogfighting" at those altitudes.

Yes, that was kind of my point a while back regarding (in practical operational terms) the somewhat lower critical altitude tuning of the -7 fit the useful performance envelope for needed power better. Service ceiling was still plenty high, and cruise performance was fine up high, but the peak power was a bit lower down. (where it was more often most useful)

Likewise, suggestions regarding the need for LW fighters to be tuned significantly above the P-51D's critical altitude seem unnecessary. (aside from specialized high alt recon aircraft, but the Germans usually employed their limited supplies of turbochargers for that) Mostly in regards to the DB-605AS/ASM's altitude performance.

 

[GregP]

Yes. It seems the "high altitude war" in th ETO gradually worked its way downward as accuracy became more important than high-altitude bombing did.

 

[Shortround6]

The "Powers That Be" in most of the countries building planes in WW II anticipated the altitudes to keep going up. However the problems with gun heating, crew heating (and health) and other equipment freezing and the slow development of pressure cabins (yes they had them but many of the early ones were almost impossible to bail out of) all combined, along with the reduced bombing accuracy from high altitudes ( and increased cloud) tended to put a practical limit of combat altitudes.
This is on top of any engine development problems.
The "anticipated" part means that they were often planing/buying things 2-4 years before actual combat use. Changing a V-1650-3 to a V-1650-7 is pretty much just using a different gear ratio/s to the supercharger so design development is almost nil and contracts can be changed in very short order to suit actual combat conditions (it could still take the US weeks if not several months to get the planes/engines from factory to front lines).

Now look at it the other way.

WHAT IF, the Germans had mounted a big supercharger on the DB605 almost from the start and stuffed it into the 109Gs with Pressure cabins in 1942??
The "technology" was nothing out of the ordinary or extreme. Granted the Germans did have trouble with the DB 605 and up-rating in 1942 but it is not a great stretch.

What kind of engines (and aircraft or modified aircraft) would the British and Americans have been howling for use in late 1943 and 1944?

 

[GregP]

Good question,Shortround.

Had the Germans gotten into very high altitude capabilitiers, my question would be whether to ignore them and bomb from 20 - 25,000 feet anyway or have the escorts we had anyway but develop dedicated high-altitude engines for the high-cover mission aircraft. Likely they would have developed the high-altitude capability and I'm thinking supercharger - turbocharger combination since that is what we did hsitorically in the P-38 and P-47.

However, there is also nothing wrong with adopting a variant of the Hooker 2-stage supercharger used on the Merlin, but tailored to the engines we were developing/using. A 2-stage Allison or a development effort on the V-1650 come to mind, and well as development of the high-atitude boost on the R-2800. The development on the V-1650 makes the most sense. Late in the fray they did run the V-1650-19 with a hydraulically variable supercharger drive, but the war was essentially over/winding down and jets were coming down the pike on high priority.

I really don't see needing a new engine ... just a better boost system, and it would not be that big of a stretch. It was more a matter of need and the resources. Had we needed the altitude capability, I am certain it would have been forthcoming with existing engines.

But, that's just my thoughts on it.

In reality, they might have developed a special high-altitude engine that was a completely new item. That would be a real stretch since developing the existing engines was NOT a quick project for the V-1710 or R-2800. The ONLY reason it was relatively quick for the Merlin is that Rolls-Royce had already developed the Merlin and we were just tooling up for it, not inventing it.

I don't think a new, high-altitude engine was going to be fielded in 1942 - 1943 if required in 1941 but, again, perhaps one of the abandoned engines could have been made to work given sufficient resources and priority. I also donlt think it would have been specified any earlier than 1941 by the U.S.A., but the UK might have had a specific need before that time.

I have never had much like for the Hispano-Suizas as far as a fighter engine goes, and do not believe it could have been made a lot more powerful and altitude-capable simultaneously; the quality was good but the engine was not comparable to other engines' power levels. The Russian engines were OK, but nothing to write home about ... yet they fielded several very high-altitude prototypes. I have no feel whatsoever for the possibilities of a Soviet high-altitude engine development making its way out of the Soviet Union, but doubt it would have been adopted in any case. I am unaware of any South American or Canadian high-altitude fighter engines that could have been developed, either. That leaves development of the existing engines or variants of same.

 

[stona]

Yes. It seems the "high altitude war" in th ETO gradually worked its way downward as accuracy became more important than high-altitude bombing did.

Throughout 1944 the 8th Air Force bombed from ever higher altitudes. Statistics from the 8th AF's ORS support this.

This, despite the fact that the same report makes clear the increased accuracy achieved from lower altitudes.

Maybe the fact that in the September to December 1944 period a large majority of US bombing was done on H2X through cloud, with very low accuracy, only 1 bomb in 500 landing within 1000' of the target and an average circular error of 2.6 miles, had something to do with a failure to reduce the bombing altitudes. This was also the end of the ludicrous pretence by some American commanders that they were precision bombing.

Cheers

Steve

 

[GregP]

I was thinking that we mostly bombed from 20,000 feet to 28 - 30,000 feet and you just showed it to be correct. Most of the P-51 escort reports I have read go from about 18,000 feet to about 25,000 feet or so, maybe a touch higher, but very few.

But we avoided bombing from above 30,000 feet due to inaccuracy.

Most of the Luftwaffe high-altitude fighters had service ceilings way above 25,000 feet, as did ours, even running the V-1650-7. If I were bombing from 23,000 feet, I'd ignore Luftwaffe fighters that were flying at 35,000 feet or send in some advance high-altitude escorts to clear them out and at LEAST render them occupied. I'd be much more worried about Lyftwaffe fighters flying at 20,000 to 25,000 feet since they would be in position for repeated attacks instead of a dive through the formation and then gone.

 

[drgondog]

The P-51's needed to be tuned to the actual bombing altitude of the 1,000-plane raids, not the Luftwaffe's top fighters. Their job as escort was to protect the bombers, not get higher than the highest German fighters. If the Luftwaffe was diving through the formation, they were already higher and enough P-51's had to STAY with the bombers so they would not be abandoned to what German fighters were left.

Mostly true Greg - but typical escort altitude for 1st and 3rd Division B-17s was 28-30K for high cover, with the other two squadrons in an escort group at different locations by directives of CO

The -3 or -7 didn't matter much to the mission, just to individual fighter vs. fighter situations.

It made some difference to those fighters in the 'high altitude' escort station.

The -7 P-51D could get to over 41,000 feet, and if they had a "high cover" force, it had 500+ miles to get that high at cruise speed and, if there WAS a need and a mission element for P-51D's to get way up high, then they were probably there when they needed to be there. Any combat at 35,000+ feet in WWII was a 2.8 - 3.1 g thing that went downhill very fast. There were no hard breaks or the hard-breaking pilot would stall and fall several miles before recovering. About all they could do was to make gentle turns or a roll and dive. They surely weren't doing much climbing fighting, Lufbrey circling, or "dogfighting" at those altitudes.

If you haven't read the Pearls of Wisdom published by 8th FC in May 1944 it will give you insight to fighter escort tactics practiced after Eaker left and Doolittle took over 8th BC.

German interceptors did try to lure escorts into chasing a few diving fighters but mostly this was taken care of by dispatching a flight, maybe section while the rest of the Squadron maintained position.

 

[Koopernic]

Throughout 1944 the 8th Air Force bombed from ever higher altitudes. Statistics from the 8th AF's ORS support this.

Maybe the fact that in the September to December 1944 period a large majority of US bombing was done on H2X through cloud, with very low accuracy, only 1 bomb in 500 landing within 1000' of the target and an average circular error of 2.6 miles, had something to do with a failure to reduce the bombing altitudes. This was also the end of the ludicrous pretence by some American commanders that they were precision bombing.

Steve

The problem with saying the Americans is inaccurate in daylight high altitude bombing is in the understanding of the data. When a computing bombsight was used it could be deadly accurate, good enough to hit a moving ship with a stick of bombs.

However a big box formation of B-17s and B-24 following a lead bombardier covers hundreds of feet of airspace in width and depth and this is why a great many bombs fall outside a 500ft radious circle. In many case of course the Americans were after a big target: something like a dock works, steal works, BMW engine plant covers hundreds of meters and a spread of bombs over hundreds of meters is actually desirable.

It was accurate and the Germans noted themselves that the USAAF was far more destructive than bomber command in terms of production. The USAAF destroyed a lot more machinery that simply could not be replaced, whereas the victims and survivors of Area Bombardment and Firebombing could be evacuated from the rubble to live arduous and uncomfortable lives elsewhere.

On those days the USAAF was able to use their optical bomb sights, perhaps 30%-50% of the of the time depending on time of year, they were extremely destructive and fairly accurate. When they used the British methods of radar bombing their accuracy was very poor and the poor accuracy statistically dilutes their achievement in optical bombing in good conditions.

On those days they may as well have just dumped their bombs in an outlying field, spared themselves some FLAK damage and turned back.

There were of course a multiple methods: radar bombing could work well in coastal areas if the city had rivers and lakes and there was the use of aids such as Oboe, GEE-H and the American Micro-H. The latter were surprisingly inaccurate in field use given their very high accuracy in tests.

Systems such as Micro-H and Gee-H could control perhaps 50 bombers at once and guide them to better than 100 yards though the bombs spread over 20 times that distance. One opperations report has Micro-H spreading its bombs over 5 MILES.

 

[stona]

Getting of subject, but US bombing in formation in the ETO was SUBSTANTIALLY more accurate when bombing was done on the cue of a lead bombardier (bomb aimer to the Brits). From late 1943 until the end of the war this became SOP for the US air forces in Europe.
I've already posted this somewhere, in a more relevant thread, but here it is again.

This report was the foundation of the reason for the change to 'bombing on cue'. It also guessed at why this method was so much more accurate.

Accuracy when bombing visually in good conditions was always decent, and actually improved as time went by. Bombing 'blind' on radar was always inaccurate, a problem not just for the Americans. Bomber Command bombing in poor conditions on blind marking, often on sky markers when ground target indicators were obscured, was often just as bad.

Cheers

Steve

 

[kool kitty89]

Good question,Shortround.

Had the Germans gotten into very high altitude capabilitiers, my question would be whether to ignore them and bomb from 20 - 25,000 feet anyway or have the escorts we had anyway but develop dedicated high-altitude engines for the high-cover mission aircraft. Likely they would have developed the high-altitude capability and I'm thinking supercharger - turbocharger combination since that is what we did hsitorically in the P-38 and P-47.

If a major threat had materialized in that altitude range, the XP-38K and XP-47J would have likely seen more interest due both to the added all-around performance and particularly their high service ceilings. For either to be really practical, they'd need to have dive recovery flaps fitted given how close to critical mach they'd be at high altitude.

That would even be relevant if high flying jets had become an earlier (let alone common) threat. P-47J more so there given the higher level top speed and mach limits over the P-38. Both could fly several thousand feet above the Me 262's ceiling as well, so could potentially bounce lower flying jets with diving attacks. (granted that's assuming identical 004 engines, not some hypothetical 003 -let alone HeS 006 powered alternate arrangement -and either way the P-38 and P-47 would be riding though critical mach with semi-controlled dives likely requiring flaps to recover)


Lack of cockpit pressurization would be a problem, though. (the P-47 was fairly highly regarded for pilot comfort from what I recall -in terms of instrument configuration, seat position, overall cockpit space, heating and noise levels, so altitude sickness issues might have been more tolerable as well)

 

[wuzak]

The problem with saying the Americans is inaccurate in daylight high altitude bombing is in the understanding of the data. When a computing bombsight was used it could be deadly accurate, good enough to hit a moving ship with a stick of bombs.

At what altitude, speed?

How many bombs in the stick and how many hit the ship?

Systems such as Micro-H and Gee-H could control perhaps 50 bombers at once and guide them to better than 100 yards though the bombs spread over 20 times that distance. One opperations report has Micro-H spreading its bombs over 5 MILES.

What is Micro-H?