German answer to the WAllies introducing the P-47 + DTs and Mustang Mk.X in June of 1943?

[tomo pauk]

The P-47s in question carry the 108/110 drop tank under the belly, while the Mustang X has the original 180 gals of fuel internally + two British 54 US gal (45 imp gal; the type used sometimes on Hurricanes) tanks under the wings. The two Allied fighters can reach to about Hamburg or Frankfurt, and there are hundreds of these fighters in service; there is a supply of the drop tanks to support this. They give the LW defenders a proper mauling during already before the summer is over, and the things can only get worse for the LW, as well as the ones on the receiving end of the Allied bombing. Germans don't know when the long-range Spitfires will be also included - IOW, expect the worst case scenario there, too.

This is where the German answer starts, 1st tossing the ideas around, and then making the actual hardware (aircraft & the supporting bits & pieces; the Flak development can get another thread).

Note that this thread is not about what RAF aircraft gets the cameras, nor what gets sent to Russia.

 

[z42]

So you're sort of saying what if "big week" happens some 7 months earlier than historically?

What CAN they do, at short notice, beyond running in circles in a panic? Maybe not that much?

Avoid getting into high altitude fights with the Allied fighters? Yes, this would mean high altitude strategic bombing would face no fighter opposition as long as they are within escort range?

 

[tomo pauk]

So you're sort of saying what if "big week" happens some 7 months earlier than historically?

Not that it just happens, but keeps happening

What CAN they do, at short notice, beyond running in circles in a panic? Maybe not that much?

Not just on the short notice. While some plans can be put into the motion in a short time, some will need to wait into 1944 to materialize.

 

[mack8]

I imagine reviving the Fw-190C, accelerating the Fw-190D, prioritizing the Ta-152 and Me-262 jet fighters would be logical answers, together with reducing bomber and other non-fighter production. In effect a Jagernottprogram a year early. Paradoxically, this might have a worse effect on USAF and RAF offensive, they were not as powerful/numerous in 1943 as they were in 1944, and the germans would have prioritized fighter production earlier meaning many more fighters in 1944 to oppose the allies, plus they would have had more experience in learning to fight the allied fighters. So the attrition war would probably be more protracted, with much increased allied losses, slower rate of damage on critical german production such as oil etc. All in all probably a more even bloodbath in the air, and how this will affect 1944 and 1945 certainly might change significantly from the OTL events.

 

[tomo pauk]

I imagine reviving the Fw-190C, accelerating the Fw-190D, prioritizing the Ta-152 and Me-262 jet fighters would be logical answers, together with reducing bomber and other non-fighter production. In effect a Jagernottprogram a year early. Paradoxically, this might have a worse effect on USAF and RAF offensive, they were not as powerful/numerous in 1943 as they were in 1944, and the germans would have prioritized fighter production earlier meaning many more fighters in 1944 to oppose the allies, plus they would have had more experience in learning to fight the allied fighters.

The Me 410 is certainly axed, so are the Jumo-powered Ju 188s. The Ta 152 to be Ta 152 requires the Germans making 2-stage big V12s - this might've happen by mid-1994 1944 if they push really hard? Jet engines - can these be made in the required quantities come 1944? The Voksjaeger program is most likely to be around by late 1943 in the paper, with 1st examples flying by Spring of 1944; this puts a new burden on the jet engine supply.
(sorry for all the question marks)
Several things will not go in the German favor in this scenario of mine. The new and improved aircraft need to be flown by someone capable, that will be a problem with the increased attrition of 1943 vs. the historical situation. US bomber will not just grew in numbers faster, but the damage they will be dealing already in the last 3-4 months of the good weather operation would've been increased. Then, there is the fuel situation, especially with Me 262 in the picture, and despite the possible greater destruction of fuel facilities (that might or might not happen, the Allied target allocation in 1943 was not focused on the fuel infrastructure).

 

[z42]

The Ta 152 to be Ta 152 requires the Germans making 2-stage big V12s - this might've happen by mid-1994 if they push really hard?

By 1994 even the dysfunctional German engine development programs ought to be able to produce a 2-stage supercharged engine. Just requires the Wehrmacht to hold the line for another 50 years.

Jokes aside, the Ta152 family also included the 152C which IIRC wasn't particularly optimized for high altitude. So which Ta152 variant are we talking about? Ta 152H might be unnecessarily extreme, optimized for even higher altitudes?

In any case, yes they absolutely need better performance at ~25k in order to do something useful with the new Allied fighters around.

Jet engines - can these be made in the required quantities come 1944? The Voksjaeger program is most likely to be around by late 1943 in the paper, with 1st examples flying by Spring of 1944; this puts a new burden on the jet engine supply.

Un-canceling the He 280 and the HeS 30 might be the best option for getting jets into service ASAP?

The Luftwaffe's problems later in the war are lack of fuel and competent pilots. Not sure that sending hordes of very green pilots out in crap planes, even if jet powered like the Volksjäger, will accomplish much except getting them killed and wasting precious fuel.

Then, there is the fuel situation, especially with Me 262 in the picture, and despite the possible greater destruction of fuel facilities (that might or might not happen, the Allied target allocation in 1943 was not focused on the fuel infrastructure).

Jets might actually be a blessing in disguise? Yes, the early jets weren't particularly fuel efficient, but a characteristic of turbines is that they aren't very particular about the fuel, as long as it doesn't gel at altitude. No need to worry about not keeping up with the Allies in the octane race.

 

[tomo pauk]

By 1994 even the dysfunctional German engine development programs ought to be able to produce a 2-stage supercharged engine. Just requires the Wehrmacht to hold the line for another 50 years.

Jokes aside, the Ta152 family also included the 152C which IIRC wasn't particularly optimized for high altitude. So which Ta152 variant are we talking about? Ta 152H might be unnecessarily extreme, optimized for even higher altitudes?
In any case, yes they absolutely need better performance at ~25k in order to do something useful with the new Allied fighters around.

The Ta 152C was also using the engine with the 2-stage compressor, this time on the DB 603L engine. Removing the GM1 from considertaion, both of these were well suited for fight on high altitudes, and also not too shabby at lower altitudes.
Yes, they need to have the ~700 km/h fighters by at least early Spring of 1944 if these are to matter.

Un-canceling the He 280 and the HeS 30 might be the best option for getting jets into service ASAP?

That would've been a move here, indeed.

The Luftwaffe's problems later in the war are lack of fuel and competent pilots. Not sure that sending hordes of very green pilots out in crap planes, even if jet powered like the Volksjäger, will accomplish much except getting them killed and wasting precious fuel.

+1 on that.

Jets might actually be a blessing in disguise? Yes, the early jets weren't particularly fuel efficient, but a characteristic of turbines is that they aren't very particular about the fuel, as long as it doesn't gel at altitude. No need to worry about not keeping up with the Allies in the octane race.

Jets will happily go along even with the under 70 oct fuel, as well as with other fuels like the diesel or kerosene.
If that can be poured into the tanks of the 1-engined fighter, they can stretch that fuel a lot more.

 

[mack8]

I agree that Ta-152H was too extreme, just mate the C airframe with the Jumo-213E, presumably the speed would be in the same ballpark, about 730-740kph, enough to give an edge over the P-51B/D and Spitfire Mk.14?

I'm no big fan of the He-162, it was too much of a desperation plane, even if more expensive He-280 is a better plane, so have Heinkel focus on it, while Messerschmitt does same with the Me-262. The next step would be a swept wing design such as some form of Ta-183 or similar designs from other companies, but that's just a healthy dose of hindsight. Would the germans push forward their SAMs too in this TL? It would be disastruous for the allies if the germans field large numbers of jet fighters, high alt prop fighters AND effective enough SAMs.

Also, would the allies still have air superiority for D-day if the germans activate a Jagernottprogram earlier say fall 1943 or so? Butterflies, butterflies...

The above though is a fairly ideal scenario as far as german response would be to long range allied fighters in mid-1943, it's possible their actual response might not be as effective/efficient as proposals here.

 

[tomo pauk]

I'm no big fan of the He-162, it was too much of a desperation plane, even if more expensive He-280 is a better plane, so have Heinkel focus on it, while Messerschmitt does same with the Me-262.

I don't see the He162 as a synonym for an 1-engined jet fighter
Germans will need to whip up something more docile, and perhaps using the other aircraft as part donors in order to speed up the production (besides the landing gear).

Also, would the allies still have air superiority for D-day if the germans activate a Jagernottprogram earlier say fall 1943 or so? Butterflies, butterflies...

Allies would not sat idle. The obvious & historical things - a 'proper' Merlin Mustang, P-47 with more fuel and drop tanks, debugged P-38- are set in the stone. Upping the internal fuel on the Spitfires and Tempest taking place in early 1944 instead of by late summer of 1944 is also in the cards - not doing that will steal all the limelight from the British-made fighters.
There is also the effects of the earlier/higher pilots' attaition to account for, ditto for the greater number of US bombers surviving into 1944, as well as the greater impact on the German industry.

The above though is a fairly ideal scenario as far as german response would be to long range allied fighters in mid-1943, it's possible their actual response might not be as effective/efficient as proposals here.

Yeah, it took them almost through whole 1944 to came out with the Fw 190D fighter and the BMW 801S engine, despite the situation going from problematic to very serious from Autumn of 1943 to the early 1944.

 

[Howard Gibson]

The P-47s in question carry the 108/110 drop tank under the belly, while the Mustang X has the original 180 gals of fuel internally + two British 54 US gal (45 imp gal; the type used sometimes on Hurricanes) tanks under the wings. The two Allied fighters can reach to about Hamburg or Frankfurt, and there are hundreds of these fighters in service; there is a supply of the drop tanks to support this. They give the LW defenders a proper mauling during already before the summer is over, and the things can only get worse for the LW, as well as the ones on the receiving end of the Allied bombing. Germans don't know when the long-range Spitfires will be also included - IOW, expect the worst case scenario there, too.

This is where the German answer starts, 1st tossing the ideas around, and then making the actual hardware (aircraft & the supporting bits & pieces; the Flak development can get another thread).

Note that this thread is not about what RAF aircraft gets the cameras, nor what gets sent to Russia.

Flying over the enemy with drop tanks, and with long range aircraft in general, puts you at a disadvantage in a knock 'em down drag 'em out fight. You must have some technological advantage to make up for all this.

In early 1943, all the American aircraft were turbocharged, and combat happened at high altitudes that completely suited the P47 Thunderbolts. The Germans needed turbochargers or two-stage superchargers moved into production and service. Apparently, the Luftwaffe's job was to support the Heer (army) on the ground, so high altitude kit was discouraged.

In the real war, two-stage superchargers were being manufactured in Germany in 1945, too late to affect the war. Could they have produced these earlier? I wonder.

American turbochargers were the work of Doctor Sanford Moss at General Electric. Moss did his doctoral thesis on gas turbines in 1903. These were developed at the end of WWI, and with peace, the USAAC quickly lost interest. Moss' team was kept together, and they were ready in the late thirties when the USAAC got interested again.

Stanley Hooker was a mathematician with an interest in hydrodynamics. He did his doctoral studies on mechanical engineering, and supersonic airflow. Rolls Royce hired him to work on Merlin superchargers. The impellers were 10.25 inches in diameter, and they spun at 28,000rpm. Do the math. Hooker claimed that the original Merlin supercharger was the best in the world, but he quickly improved on it.

A big part of allied success at high altitude was the work of two men. There were lots of good reasons for not putting up with either of them.

In an alternate history, GE shuts down its turbocharger program in 1919. James Ellor get pissed off at Hooker's criticism of his supercharger, and gets him fired. In general, the Germans were very good at technology, especially aerodynamics. Their technology works, and they inflict unacceptable casualties on the Americans in daylight bombing. The Americans join the British in night bombing, and the Luftwaffe day fighter pilots do not take the massive losses the American inflicted in the real war. This could be a problem on D-Day.

Note how night bombing was not done from high altitude. Single-stage supercharged Mosquito intruders still have excellent performance, and are a threat to German night fighters.

Without two-stage superchargers, Mosquitos do not fly with near impunity all over Europe, and allied photo reconnaissance is not nearly as effective as it was in the real war.

Perhaps the Germans developed two-stage superchargers as fast as was practicable. What the Germans really need is for the allies to screw up and not create an advantage at high altitudes!

 

[tomo pauk]

Some engines' possibilities:
- Turboed BMW 801 for the Fw 190, like found on this drawing. Benefits - BMW (the maker of that turbo) can probably make more of these than they can make the jet engines; power at high altitudes is excellent; turbo ancilliaries are reasonably tucked in. Shortcoming - the stream of the hot exhausts still coming towards the windscreen. Probably get rid of the fuselage guns & ammo, and add the 'plug' as on the D9 to counter-ballance the now heavier nose.
- The BMW 801 with a proper S/C. Low-hanging fruit is the S/C from the 801E, the best would've been the 2-stage S/C, like on the BMW 801R, or the P.8028 engine (that shared the layout of the P&W 2-stagers).
- Get the DB to have the DB 605AS equivalent in the works. It will take a bit to debug the basic 605, but the 605AS is the top priority after that.
- Not really an 'engine possibility', but design the blended external intakes for the Fw 190, so the altitude power can be improved without being to draggy. Like on the La-7, or like this for the actual Fw 190 (note also the improved oil cooler installation for lower drag) - too late, of course.

Jamming a jet engine in/on the Fw 190 or Bf 109?

 

[Shortround6]

American turbochargers were the work of Doctor Sanford Moss at General Electric. Moss did his doctoral thesis on gas turbines in 1903. These were developed at the end of WWI, and with peace, the USAAC quickly lost interest. Moss' team was kept together, and they were ready in the late thirties when the USAAC got interested again.

USAAC didn't have much money but they did trickle some to Moss in the late 20s and into the 30s. I think I once counted over 100 turbo charged American aircraft before Sept 1939 (?) but since 50/51 of these were the P-30s of 1934-36 (last delivery Aug 1936) It is a bit distorted. The USAAC wanted turbo superchargers, but................they want ones that worked, they were willing to fund experiments, but they knew they were experiments and the late 1930s planes were NOT ready for squadron service, at least in fighters.

In the real war, two-stage superchargers were being manufactured in Germany in 1945, too late to affect the war. Could they have produced these earlier? I wonder.

You not only need the turbo itself, you need high temperature steel alloys, you need intercoolers, you need a turbo regulator and you need high octane fuel.
Junkers made some turbo diesels, these worked, in part because diesel exhaust is cooler than exhaust from petrol engines.

Now with a mechanical two stage supercharger you don't need the high temperature alloys but you need most of the other stuff. P-63 tried to not use an intercooler. Performance over 25,000ft kind of sucked. It was a lot better than a P-39 but water injection only goes so far. And P-63 was carrying as much water and water injected P-47 did.

 

[Howard Gibson]

USAAC didn't have much money but they did trickle some to Moss in the late 20s and into the 30s. I think I once counted over 100 turbo charged American aircraft before Sept 1939 (?) but since 50/51 of these were the P-30s of 1934-36 (last delivery Aug 1936) It is a bit distorted. The USAAC wanted turbo superchargers, but................they want ones that worked, they were willing to fund experiments, but they knew they were experiments and the late 1930s planes were NOT ready for squadron service, at least in fighters.

You not only need the turbo itself, you need high temperature steel alloys, you need intercoolers, you need a turbo regulator and you need high octane fuel.
Junkers made some turbo diesels, these worked, in part because diesel exhaust is cooler than exhaust from petrol engines.

Now with a mechanical two stage supercharger you don't need the high temperature alloys but you need most of the other stuff. P-63 tried to not use an intercooler. Performance over 25,000ft kind of sucked. It was a lot better than a P-39 but water injection only goes so far. And P-63 was carrying as much water and water injected P-47 did.

The German two-stage superchargers were the same as the Merlin two-stage superchargers, two compressors on the one shaft, driven however indirectly, from the engine. High temperature alloys are only needed for exhaut driven turbochargers.

Intercoolers are useful when there is a significant temperature difference between the supercharged air and ambient. This seems to happen on cars with positive displacement compressors like Rootes blowers, although the word "Intercooled" looks very cool on the back of the car, just above the bumper. Single stage centrifugal compressors generally do not generate the temperature and pressure to make an intercooler worthwhile. Two centrifugal compressors do make them work. The intercooler creates air resistance at the intake manifold. They are not automatically a Good Thing.

 

[Howard Gibson]

Some engines' possibilities:
- Turboed BMW 801 for the Fw 190, like found on this drawing. Benefits - BMW (the maker of that turbo) can probably make more of these than they can make the jet engines; power at high altitudes is excellent; turbo ancilliaries are reasonably tucked in. Shortcoming - the stream of the hot exhausts still coming towards the windscreen. Probably get rid of the fuselage guns & ammo, and add the 'plug' as on the D9 to counter-ballance the now heavier nose.
- The BMW 801 with a proper S/C. Low-hanging fruit is the S/C from the 801E, the best would've been the 2-stage S/C, like on the BMW 801R, or the P.8028 engine (that shared the layout of the P&W 2-stagers).
- Get the DB to have the DB 605AS equivalent in the works. It will take a bit to debug the basic 605, but the 605AS is the top priority after that.
- Not really an 'engine possibility', but design the blended external intakes for the Fw 190, so the altitude power can be improved without being to draggy. Like on the La-7, or like this for the actual Fw 190 (note also the improved oil cooler installation for lower drag) - too late, of course.

Jamming a jet engine in/on the Fw 190 or Bf 109?

There were a number of problems with Germany's jet engines in WWII. The important one was their inability to make heat resistant turbines. This messes up turbochargers as well. Mechanical two-stage superchargers were the way forward.

 

[tomo pauk]

Now with a mechanical two stage supercharger you don't need the high temperature alloys but you need most of the other stuff. P-63 tried to not use an intercooler. Performance over 25,000ft kind of sucked. It was a lot better than a P-39 but water injection only goes so far.

Even a non-ideal 2-stage is a better deal than a very good 1-stage S/C.

 

[tomo pauk]

There were a number of problems with Germany's jet engines in WWII. The important one was their inability to make heat resistant turbines. This messes up turbochargers as well. Mechanical two-stage superchargers were the way forward.

Already by 1942, BMW have had a working turbo that used the hollow blades for the turbine. That kept the turbine from melting, and was operationally used on the Ju 388s.
But I agree that a 2-stage S/C was a better choice for them.

 

[Shortround6]

Single stage centrifugal compressors generally do not generate the temperature and pressure to make an intercooler worthwhile. Two centrifugal compressors do make them work. The intercooler creates air resistance at the intake manifold. They are not automatically a Good Thing.

That is general consensus. Junkers thought they knew better and stuck an intercooler/after cooler on the 211J, that while it didn't seem to do a lot for take-off power it may have been good for about 140hp at 16,500-17,000ft when climbing (2400rpm at 1.25 ata ). Of course they weren't to worried about weight or drag on a He 111 or JU 88.
Might not have been a good trade off on a single engine fighter.

Once you go to two stages things get a lot more complicated. chart in an old text book shows temperature in Fahrenheit rise in a compressor trying to deliver sea level pressure (29.92in Hg) at altitude from 0 to 40,000ft using a supercharger that has a 0.65 temperature co-efficient. (American superchargers were not as efficient as they could/should have been).
altitude.................................temp rise
10,000ft....................................80
15,000ft..................................140
20,000ft..................................170
25,000ft..................................220
30,000ft..................................260
35,000ft..................................310

Now if you are delivering higher pressure air the temp is going to be higher but we do have to subtract the ambient air temperatures at the higher altitudes. At 25,000ft under standard conditions the air as at -30 degree F so the inlet air to the 2nd stage will be at 130 degrees instead of the sea level 59/60 degrees the engine may have been rated at sea level. Off course the raised temperature just goes than much higher in the 2nd stage.
US planes with turbos were supposed to giving the engine supercharger no more than 100 degree air at 25,000ft ( sometimes they didn't succeed, especially the P-38G/H) Turbo itself was not efficient and intercooler was too small. Intercooler fixed on the P-38J.
Two stage supercharger with out intercooler on the P-63 managed to raise the military power (1125-1150hp) from 15,500ft to 22,400ft on the over 900 early planes compared to the late P-39s.
But that may just show how bad the US (Allison) two stage setup was. Merlin 46 could make 1100 at 22,000ft with a single stage compressor
RR claims they could have gotten 1100hp at 26,000ft with an intercooler and a higher gear ratio but that would have cut take off power to 940hp.
No idea of how heavy the RR intercooler was or how much drag it would have caused.
Germans did tend use lower pressures and so less temperature rise but if they are trying to fight in that 25,000-35,000ft area they really need to think about the intercoolers.

 

[Howard Gibson]

Once you go to two stages things get a lot more complicated. chart in an old text book shows temperature in Fahrenheit rise in a compressor trying to deliver sea level pressure (29.92in Hg) at altitude from 0 to 40,000ft using a supercharger that has a 0.65 temperature co-efficient. (American superchargers were not as efficient as they could/should have been).
altitude.................................temp rise
10,000ft....................................80
15,000ft..................................140
20,000ft..................................170
25,000ft..................................220
30,000ft..................................260
35,000ft..................................310

Now if you are delivering higher pressure air the temp is going to be higher but we do have to subtract the ambient air temperatures at the higher altitudes. At 25,000ft under standard conditions the air as at -30 degree F so the inlet air to the 2nd stage will be at 130 degrees instead of the sea level 59/60 degrees the engine may have been rated at sea level. Off course the raised temperature just goes than much higher in the 2nd stage.
US planes with turbos were supposed to giving the engine supercharger no more than 100 degree air at 25,000ft ( sometimes they didn't succeed, especially the P-38G/H) Turbo itself was not efficient and intercooler was too small. Intercooler fixed on the P-38J.
Two stage supercharger with out intercooler on the P-63 managed to raise the military power (1125-1150hp) from 15,500ft to 22,400ft on the over 900 early planes compared to the late P-39s.
But that may just show how bad the US (Allison) two stage setup was. Merlin 46 could make 1100 at 22,000ft with a single stage compressor

Those numbers you quote are for temperature rise, not the actual temperature. You have accounted for ambient. What matters is the ratio between the temperatures, which makes high altitude more efficient.

I don't know about the Merlin_46, but the Merlin_45 was optimized for relatively high altitudes. They sacrificed low altitude performance to get it.

 

[Shortround6]

Those numbers you quote are for temperature rise, not the actual temperature. You have accounted for ambient. What matters is the ratio between the temperatures, which makes high altitude more efficient

Read the paragraph under the numbers listed. I explained it.

I don't know about the Merlin_46, but the Merlin_45 was optimized for relatively high altitudes. They sacrificed low altitude performance to get it.

The 46 was more of the same, more optimized for higher altitudes (larger rotor) than the 45 but even worse at low level/take off. Just trying to show that the US was not even close to leading the pack when it came to actual compressor design.
How good the Germans were is subject to question. They did a real good job with the DB605 AS with 1200PS at 8000 meters using the supercharger from the DB603. Only lost about 40hp for take-off. I don't how or if they adjusted the variable speed drive on the supercharger. May be the German companies didn't share information well? Some of the allies sure didn't.

 

[Howard Gibson]

Read the paragraph under the numbers listed. I explained it.

The 46 was more of the same, more optimized for higher altitudes (larger rotor) than the 45 but even worse at low level/take off. Just trying to show that the US was not even close to leading the pack when it came to actual compressor design.
How good the Germans were is subject to question. They did a real good job with the DB605 AS with 1200PS at 8000 meters using the supercharger from the DB603. Only lost about 40hp for take-off. I don't how or if they adjusted the variable speed drive on the supercharger. May be the German companies didn't share information well? Some of the allies sure didn't.

As I noted above, a big part of allied superiority at supercharging was two guys. Apparently, Moss possessed "that disarming characteristic of small boys with whom it's impossible to be angry for long in spite of a somewhat exasperating behavior."[ref] It sounds like maybe they could not bear to fire the guy. In his biography, Stanley Hooker was impressed at the office politics at Rolls Royce. Rolls Royce created a supportive office culture. Lots of other companies were war zones. Hooker would not have survived in them.

Nazi Germany were the masters of nasty office politics. Definitely, this helped the allies win the war.