Japanese Radial Engine Developments shared with Germany

[tomo pauk]

Radial engines instead of the Jumo 211 for the Ju-87 (or equivalent) runs into a problem.
Once you get to the "B" series they have 1200hp for take-off. The Germans do not have a 1200hp radial at the time.
They barely have 1000hp radial and prospects for more power are slim (water injection?).

The Ju-87B was initially hauling a 500 kg bomb, and was up-rated to the 1000 kg bomb by 1940. On a 1000 HP engine.
The Ju-87R was rated for a 500 kg bomb and two drop tanks, and was also up-rated for the 1000 kg bomb + two drop tanks. Also on 1000 HP.

Germans also need the Radials for other projects. They are not quite the 2nd tier engines that are sitting in warehouses.
The radials were powering many aircraft that may not have been in the spotlight but did things that needed doing.
The Hs 126 doesn't get a lot of love but it equipped 47 army cooperation squadrons in the attack on Russia in 1941.
As bomber it was crap, but if the army commanders do not have good recon then things don't go well.

Indeed, the Hs 126 was a crappy bomber. It was also too much of a short-range recon. Sorta German Lysander?
So make more of the Fi 156s, you might get perhaps 3 of those for each 2 of the Hs 126s not produced? Also, one could fuel perhaps 3 Strorchs with the amount of fuel one Hs 126 used.
Frees 900+ radial engines.

Then the Do 17 later versions - neither speed, nor bomb load, nor defensive firepower worth talking about. rather have Dornier making the He 111s, at least these carried more than double the bomb load, aircraft vs. aircraft.

 

[MikeMeech]

The Ju-87B was initially hauling a 500 kg bomb, and was up-rated to the 1000 kg bomb by 1940. On a 1000 HP engine.
The Ju-87R was rated for a 500 kg bomb and two drop tanks, and was also up-rated for the 1000 kg bomb + two drop tanks. Also on 1000 HP.


Indeed, the Hs 126 was a crappy bomber. It was also too much of a short-range recon. Sorta German Lysander?
So make more of the Fi 156s, you might get perhaps 3 of those for each 2 of the Hs 126s not produced? Also, one could fuel perhaps 3 Strorchs with the amount of fuel one Hs 126 used.
Frees 900+ radial engines.

Then the Do 17 later versions - neither speed, nor bomb load, nor defensive firepower worth talking about. rather have Dornier making the He 111s, at least these carried more than double the bomb load, aircraft vs. aircraft.

Hi
As the Hs 126 was designed and used as a two-seat Tactical Reconnaissance and Army Co-operation aircraft (Yes, just like the Lysander), but could carry ten 22-lb bombs internally or, occasionally, one 110-lb bomb externally, it would be a "crappy bomber". But, its designed role was what the Luftwaffe wanted in the late 1930s, just like other nations designed similar aircraft for the role.

Mike

 

[tomo pauk]

Hi
As the Hs 126 was designed and used as a two-seat Tactical Reconnaissance and Army Co-operation aircraft (Yes, just like the Lysander), but could carry ten 22-lb bombs internally or, occasionally, one 110-lb bomb externally, it would be a "crappy bomber". But, its designed role was what the Luftwaffe wanted in the late 1930s, just like other nations designed similar aircraft for the role.

Mike

I agree with what you've wrote.
However, my understanding is that these aircraft were not the money best spend. Thus my suggestion that Hs 126 in production and use is replaced by the light recon aircraft and a real bomber. That bomber can still double as the Army support aircraft, while delivering the greater firepower when needed, and can also be used as a 'real' bomber. Not unlike what the Hs 123 and Ju 87 were used for.

 

[Shortround6]

The Ju-87B was initially hauling a 500 kg bomb, and was up-rated to the 1000 kg bomb by 1940. On a 1000 HP engine.

Sources are contradictory. Ju-87B-1 had the 1000hp Jumo 211 A engine. The B-2s started getting 1200hp 211Da engines?

Indeed, the Hs 126 was a crappy bomber. It was also too much of a short-range recon. Sorta German Lysander?

A lot depends on the other roles and the equipment desired. What kind of radios were available and when? Radios got smaller and longer ranged during the war. Early radios were limited in range when using voice. Cameras also changed. Hs 126 had fixed camera in the rear of the cockpit and either a large hand held camera or the large camera could be detached and the operator could hang over the side. Maybe they did keep making the 126 for too long. But going over to the Storch may have been a leap of faith. Or perhaps it could not do as many different things or perhaps not without special modifications. The Hs 126 was replaced by the Fw 189, not the Storch. The Fw 189 won the contest over the Bv 141 which shows sort of the thinking of the time.

Using a BMW 801 engine for the short range recon?

Then the Do 17 later versions - neither speed, nor bomb load, nor defensive firepower worth talking about.

None of the German bombers had defensive firepower worth talking about.
One statistic is that the Do 17Z had the lowest lost rate per sortie.
However the loss rate per ton (or 100 of tons) of bombs dropped may be rather different due to the light bomb loads.
But in 1939 even before Poland the decisions had been made. The Do 17Z was being phased out and prep work for the 217 was started. The Do 217V9 was being worked in Jan 1940.

Maybe they should have stuck with Do 17 a bit longer? Stuck G-R 14N engines on them?

 

[z42]

Ju 87 was a means to the end - how to deliver a sizable bomb load in an accurate way, so that target is put out of commsion (so to say), removing any need that target needs to be attacked again, and not over a long distance (in European terms; Americans and Japanese will probably find these ranges laughably short). It was fighters job to remove the main obstacle - enemy fighters. And that worked until the LW was contested with a formidable defensive force, that used electronic devices not in use in the time Ju 87 was being designed.

Several alternatives to the Ju 87 for the late 1930s/early ww2:
- I've already suggested the SBD equivalent to be made instead (will still require that fighter force does it's job against UK, otherwise it should do 90% of what Ju 87 did while using yesterday's engines, leaving the V12s for the more shiny aircraft)
- Go 2-engine on a small aircraft, talk something sized like the Fw 187, Ki-45 or the Ki-46, but with a bomb bay or the recess for a bomb, 1000 HP radials. That should put the speed up (to perhaps 480+ km/h?), and allow that a powerful cannon is fitted along with a good bomb load.
- A fighter-bomber of size and shape of the CW 21, start out with a 250 kg bomb as the main weapon.

All of these should be easy to do as the dive bombers. Being faster and smaller (not the 2-engined design) than the Ju 87 will make them less of a target to the enemy defenses. Each should start out with some protection, and improve later. Use the captured radials once available. Try and find the best weapon loadout between the cannons, bombs and rockets.

Come 1941, the Fw 190 should be carrying the burden, while, for the targets that are more distant, something much more capable - including the better speed - should've been produced and used.

Getting a bit off-topic, and bordering on sacrilege since this is an aircraft forum, but AFAIU a lot of usage of Ju 87 and other German bombers, at least early in the war, was essentially functioning as mobile artillery for the fast moving tank units, as the horse-drawn artillery just couldn't keep up. So what about equipping sufficient SP artillery for the panzer forces? Something like the Wespe, a 105mm howitzer on a Pz II chassis, would certainly be technically possible starting in the late 1930'ies? Yet it took until 1943 before the Wespe entered service. Use the SP artillery for those missions where appropriate (within range, and typically an area target), avoiding the need to expose a very expensive aircraft and highly trained crew to the risk of getting shot down.

 

[tomo pauk]

Sources are contradictory. Ju-87B-1 had the 1000hp Jumo 211 A engine. The B-2s started getting 1200hp 211Da engines?

As you can see, they are not contradictory

A lot depends on the other roles and the equipment desired. What kind of radios were available and when? Radios got smaller and longer ranged during the war. Early radios were limited in range when using voice. Cameras also changed. Hs 126 had fixed camera in the rear of the cockpit and either a large hand held camera or the large camera could be detached and the operator could hang over the side. Maybe they did keep making the 126 for too long. But going over to the Storch may have been a leap of faith. Or perhaps it could not do as many different things or perhaps not without special modifications. The Hs 126 was replaced by the Fw 189, not the Storch. The Fw 189 won the contest over the Bv 141 which shows sort of the thinking of the time.

IMO, an early try with the Storch-equivalent to do the non-combat part of the Army cooperation would've been worthwhile for the Germans.

Using a BMW 801 engine for the short range recon?

Better not

None of the German bombers had defensive firepower worth talking about.
One statistic is that the Do 17Z had the lowest lost rate per sortie.
However the loss rate per ton (or 100 of tons) of bombs dropped may be rather different due to the light bomb loads.

Yes, german bombers will need the better defensive firepower.
Against a strategic target, a force of 100 He 111s might have done the same damage as a force of 200 Do 17s, despite being a far less of a burden to both German industry, budget, manpower and fuel. Calculating in perhaps 15 (or 7.5%) of He 111 shot down vs. 20 (or 20%) of the He 111s still has the He 111 coming out as a winner

But in 1939 even before Poland the decisions had been made. The Do 17Z was being phased out and prep work for the 217 was started. The Do 217V9 was being worked in Jan 1940.

Maybe they should have stuck with Do 17 a bit longer? Stuck G-R 14N engines on them?

Do 17 will need to be supplanted in the production lines much sooner, decision made by 1937? Seems like it was produced at two Dornier facilities (Oberpfaffenhofen, Friedirchshafen), at Henschel, B&W (HFW), and at Siebel. Perhaps keep just two factories making them, rest have He 111 produced?

Can we expect the Do 17 to up the bombload to even 1500 kg, perhaps powered by the G&R 14N engines? But then, the early He 111s were also good for 1500 kg (in the time Do 17s went from 500 kg to 750 kg) on 2x 850 HP - a figure 50% higher than the best Do 17 with 2 x 1000 HP.

Yet, the He 111 with these radials should be carrying at least 2000 kg of bombs. The same engine on the Ju 87?

 

[tomo pauk]

Getting a bit off-topic, and bordering on sacrilege since this is an aircraft forum, but AFAIU a lot of usage of Ju 87 and other German bombers, at least early in the war, was essentially functioning as mobile artillery for the fast moving tank units, as the horse-drawn artillery just couldn't keep up. So what about equipping sufficient SP artillery for the panzer forces? Something like the Wespe, a 105mm howitzer on a Pz II chassis, would certainly be technically possible starting in the late 1930'ies? Yet it took until 1943 before the Wespe entered service. Use the SP artillery for those missions where appropriate (within range, and typically an area target), avoiding the need to expose a very expensive aircraft and highly trained crew to the risk of getting shot down.

Not a sacrilege at all

I've pontificated too long on this forum that Germans sometimes over-produced some stuff (20mm flak, 37mm pak), while some other pieces of hardware were left in the meagre numbers, or/and were made too late. So I'd certainly agree with the notion that a good 10.5cm SP howitzer is produced ASAP, indeed before the ww2.

 

[z42]

Do 17 will need to be supplanted in the production lines much sooner, decision made by 1937? Seems like it was produced at two Dornier facilities (Oberpfaffenhofen, Friedirchshafen), at Henschel, B&W (HFW), and at Siebel. Perhaps keep just two factories making them, rest have He 111 produced?

Can we expect the Do 17 to up the bombload to even 1500 kg, perhaps powered by the G&R 14N engines? But then, the early He 111s were also good for 1500 kg (in the time Do 17s went from 500 kg to 750 kg) on 2x 850 HP - a figure 50% higher than the best Do 17 with 2 x 1000 HP.

Yet, the He 111 with these radials should be carrying at least 2000 kg of bombs. The same engine on the Ju 87?

If telling Dornier to license produce another aircraft, why not jump straight to the Ju 88 instead of the He 111? Ju 88 had it's first flight in late 1936, and by mid-late 1937 they knew they were onto a winner. Now it took a few more years before it entered service, so setting up another Dornier-ran shadow factory in 1937 might have been a bit too early. Then again, if Udet had not insisted on redesigning the plane for the dive bomber role, maybe it could have been ready somewhat earlier?

Sticking the G-R 14N's on the Ju 88 could have been interesting as well. Probably mostly a wash performance-wise compared to the Jumo 211, but at least it would have been a second source of engines. But if (pretty big if!) they could have produced the G-R 14 radials in sufficient numbers, could this have largely replaced the need for the Jumo 211, allowing Jumo engineering to focus more on next generation projects like the 213 and 004?

 

[yulzari]

Hi
As the Hs 126 was designed and used as a two-seat Tactical Reconnaissance and Army Co-operation aircraft (Yes, just like the Lysander), but could carry ten 22-lb bombs internally or, occasionally, one 110-lb bomb externally, it would be a "crappy bomber". But, its designed role was what the Luftwaffe wanted in the late 1930s, just like other nations designed similar aircraft for the role.

Mike

At least the Lysanders could carry 2x250lb bombs and 3 light bomb carriers of 4x80lb each.

 

[Shortround6]

If telling Dornier to license produce another aircraft, why not jump straight to the Ju 88 instead of the He 111?

A lot depends on timing. German procurement was rather convoluted. How much was do to politics (favors) and how much was due to actually shortages/allocations and how much was due to which engines and/or airframes were really ready for large scale production at any given time?
The Ju-88 changed engines and gained over 4000lbs in gross weight, also went from a 3 man crew to 4 men and went from a single 7.9mm machine gun to three.
The Ju-88 V-6 which flew in June 1938 was rated for 1100lbs internal and since the He 111 was already flying with at least double the load in combat in Spain there is little doubt that the JU-88 was NOT the way to go to replace the He-111 in 1938/39.
In fact the Ju-88 didn't fly a combat mission until Sept 26th 1939.
By this time the internal load could be as much as 28 50kg (110lb) although there were four external racks.
Here is were the Ju-88 legend starts. The Ju-88 was rather adaptable but max (or even medium) loads require external stowage and loss of speed/range. Range can be regained by sticking a fuel tank in the bomb bay(or two) but that really forces the useful load to go to large bombs outside. It wasn't quite as useful as a quick look at the specs indicate.
Most accounts say the Do-17Z could carry 20 50kg bombs inside or four 250kg bombs. The JU-88 was never set up to carry 250kg bombs inside. I am not saying the Do-17 was better. But the difference is not as much as it is sometimes made out to be.

Sticking the G-R 14N's on the Ju 88 could have been interesting as well. Probably mostly a wash performance-wise compared to the Jumo 211, but at least it would have been a second source of engines.

Again a lot depends on timing.
The Ju-88A-2 and A-5 used 1200hp Jumo B-1 engines and perhaps the 1140hp G-R 14 N48/49 engines as used in the LeO 451s would have been a good substitute, but the A-4 was supposed to use the newer 1340hp Jumo 211 engines starting in late 1940, typical German delivery problems led to the A-5 version (A-4 airframe with the older model engines) while engine production got sorted out.

Expecting G-R to figure out were to get 10% or more power out of the N series engine while occupied? In fact G-R had pretty much given up on the N series engine and were working on the R series but that was a long way from actual production (and used a 3 bearing crankshaft instead of a 2 bearing). Basically G-R kept the bore and stroke and threw out most of everything else. No production tooling existed.

 

[tomo pauk]

Expecting G-R to figure out were to get 10% or more power out of the N series engine while occupied? In fact G-R had pretty much given up on the N series engine and were working on the R series but that was a long way from actual production (and used a 3 bearing crankshaft instead of a 2 bearing). Basically G-R kept the bore and stroke and threw out most of everything else. No production tooling existed.

I'd say that 14R was a far safer bet than the Japanese engines for the Germans to had, at least when it is about the more powerful types

 

[Shortround6]

I'd say that 14R was a far safer bet than the Japanese engines for the Germans to had, at least when it is about the more powerful types

True. The Germans could at least look at a few 14R engines and not have them shipped in by submarine

 

[JuniorJarhead09]

Ju 87 was a means to the end - how to deliver a sizable bomb load in an accurate way, so that target is put out of commsion (so to say), removing any need that target needs to be attacked again, and not over a long distance (in European terms; Americans and Japanese will probably find these ranges laughably short). It was fighters job to remove the main obstacle - enemy fighters. And that worked until the LW was contested with a formidable defensive force, that used electronic devices not in use in the time Ju 87 was being designed.

Several alternatives to the Ju 87 for the late 1930s/early ww2:
- I've already suggested the SBD equivalent to be made instead (will still require that fighter force does it's job against UK, otherwise it should do 90% of what Ju 87 did while using yesterday's engines, leaving the V12s for the more shiny aircraft)
- Go 2-engine on a small aircraft, talk something sized like the Fw 187, Ki-45 or the Ki-46, but with a bomb bay or the recess for a bomb, 1000 HP radials. That should put the speed up (to perhaps 480+ km/h?), and allow that a powerful cannon is fitted along with a good bomb load.
- A fighter-bomber of size and shape of the CW 21, start out with a 250 kg bomb as the main weapon.

All of these should be easy to do as the dive bombers. Being faster and smaller (not the 2-engined design) than the Ju 87 will make them less of a target to the enemy defenses. Each should start out with some protection, and improve later. Use the captured radials once available. Try and find the best weapon loadout between the cannons, bombs and rockets.

Come 1941, the Fw 190 should be carrying the burden, while, for the targets that are more distant, something much more capable - including the better speed - should've been produced and used.

I've been of the opinion that the FW-190 should've immediately had a ground attack version. Like previous A series with an F-series equivalent, 190F-8 climbed quicker than the A-8 up to 3,000-3,500 meters. Also substitute A- series as escorts for Clean F series.
I'm taking the quicker climb rate and slightly slower top speed on the Eastern front.
Fw-187 they missed out on in my opinion.
Me: Germany had these options to fight this war differently and fucked up every single one.

 

[tomo pauk]

I've been of the opinion that the FW-190 should've immediately had a ground attack version.

There was a lot going on for the Fw 190 to be a good ground attack aircraft.
Basically the only weak point of the radial-engine powered aircraft was the oil system; make it loose oil and the engine will seize pretty soon, that will likely make the aircraft to be lost, and possibly the pilot with it . On the BMW 801, the oil cooler and tank were protected by steel armor, meaning it will be very hard to destroy the aircraft by destroying/damaging the oil system.
Aircraft itself was small, with high rate of roll, and fast - add the 3 together and it will be pretty hard to hit it with AA guns of the day. Not impossible, mind you - the 40mm Bofors gunners were killing even the V1s and kamikazes - but the chances for the 190 to survive the attention of AA gunners will be much better than what the Ju 87 or Bf 110 can expect flying the similar mission.
Last but not least, the Fw 190, even in the ground attack livery, was able to fend for itself against the enemy fighters, again something that Ju 87, Hs 129 or Bf 110 were struggling against the WAllies.

Fw-187 they missed out on in my opinion.

Making these instead of the Bf 110/210/410 series would've been a boon to the LW.

Me: Germany had these options to fight this war differently and fucked up every single one.

Germans picked the winners many times. They certainly also made a lot of mistakes on the technical level, but these are over-shadowed by the mistakes they made on the level of grand strategy.
What was not there for them and other Axis countries was the Axis equivalent of the USA, and Germany was incapable of being that.

 

[JuniorJarhead09]

There was a lot going on for the Fw 190 to be a good ground attack aircraft.
Basically the only weak point of the radial-engine powered aircraft was the oil system; make it loose oil and the engine will seize pretty soon, that will likely make the aircraft to be lost, and possibly the pilot with it . On the BMW 801, the oil cooler and tank were protected by steel armor, meaning it will be very hard to destroy the aircraft by destroying/damaging the oil system.
Aircraft itself was small, with high rate of roll, and fast - add the 3 together and it will be pretty hard to hit it with AA guns of the day. Not impossible, mind you - the 40mm Bofors gunners were killing even the V1s and kamikazes - but the chances for the 190 to survive the attention of AA gunners will be much better than what the Ju 87 or Bf 110 can expect flying the similar mission.
Last but not least, the Fw 190, even in the ground attack livery, was able to fend for itself against the enemy fighters, again something that Ju 87, Hs 129 or Bf 110 were struggling against the WAllies.



Making these instead of the Bf 110/210/410 series would've been a boon to the LW.



Germans picked the winners many times. They certainly also made a lot of mistakes on the technical level, but these are over-shadowed by the mistakes they made on the level of grand strategy.
What was not there for them and other Axis countries was the Axis equivalent of the USA, and Germany was incapable of being that.

Well American Civil had Robert E Lee and Stonewall Jackson. One was a Strategist and the other a Tactician. But neither would be one without the other.
Mistakes and greedy hands

 

[Admiral Beez]

Did the Japanese have any expertise with radial engines (or anything else) that would have benefited the Germans? Meanwhile the Germans could have provided Japan with advances radio communications, radar, snorkels for submarine and other subsurface warfare tactics. Sticking a Nakajima Homare into a Fw 190 is not going to provide any benefit.

 

[Shortround6]

A lot of these technology swaps ignore manufacturing capability.
If Japans capacity to manufacture vacuum tubes (valves) in large numbers, giving them plans for sophisticated radios and radars that need high numbers of such components doesn't do them any good. A tricky circuit that gives the same performance was existing equipment but uses fewer parts/components might be much more useful.

Did the Japanese have any expertise with radial engines (or anything else) that would have benefited the Germans?

We need to isolate some of the different "expertise" we are taking about. A few of the differences between air cooled radials and liquid cooled V-12s are cooling and bearing design.
Cooling for air cooled engines pretty much depends on the ability to manufacture closely spaced, deep, thin fins on both the cylinder barrels and heads. And you have to do it in large quantities, not hand labor on small production runs. If you can't do this it doesn't matter what kind of superchargers or fuel injection you can build. Once the engine overheats and suffers catastrophic failure any other technological attributes it has are worthless.
Germans seem to have figured out how to get around 800hp through one crankpin fairly soon and later got to 900-1000hp in each crankpin. Wither they used 7 cylinders or 9 for each crankpin is not a big problem for the crankpin/crankshaft. It is a problem for balance and vibration.

Meanwhile the Germans could have provided Japan with advances radio communications, radar, snorkels for submarine and other subsurface warfare tactics.

Se above. I will note again that the Japanese had real problems with their subs due to size. A small Japanese sub was bigger than a German type IX. They were large visual targets, they were large radar targets, they were large sonar targets. They showed up to allied sensors at longer ranges than German U-boats did. They also dove slower and turned slower meaning they had more trouble evading attacks. Even if they got snorkels, they needed large snorkels. Some Japanese subs used 2 1/2-3 times the power of German Type IX. Even a less than full power that is a lot of air and a lot of exhaust.
I am not saying that no improvements could be made. I am saying that some of the improvements may not bring big changes.

Japanese needed changes to attitude and tactics more than they needed changes to hardware for subsurface warfare.

 

[Airborne2001]

Did the Japanese have any expertise with radial engines (or anything else) that would have benefited the Germans? Meanwhile the Germans could have provided Japan with advances radio communications, radar, snorkels for submarine and other subsurface warfare tactics. Sticking a Nakajima Homare into a Fw 190 is not going to provide any benefit.

We need to isolate some of the different "expertise" we are taking about. A few of the differences between air cooled radials and liquid cooled V-12s are cooling and bearing design.
Cooling for air cooled engines pretty much depends on the ability to manufacture closely spaced, deep, thin fins on both the cylinder barrels and heads. And you have to do it in large quantities, not hand labor on small production runs. If you can't do this it doesn't matter what kind of superchargers or fuel injection you can build. Once the engine overheats and suffers catastrophic failure any other technological attributes it has are worthless.
Germans seem to have figured out how to get around 800hp through one crankpin fairly soon and later got to 900-1000hp in each crankpin. Wither they used 7 cylinders or 9 for each crankpin is not a big problem for the crankpin/crankshaft. It is a problem for balance and vibration.

Perhaps the Germans could perfect very small radial engines like the Homare given their knowledge of the BMW 801 and the Fw-190 having a very aerodynamic design?

 

[tomo pauk]

Perhaps the Germans could perfect very small radial engines like the Homare given their knowledge of the BMW 801 and the Fw-190 having a very aerodynamic design?

Homare as-is would've been a boon for the LW if they can have it in numbers required. Power was in the ballpark of the BMW 801S, and both the small size and low weight are a good thing to have on an engine that goes into the fighters.
Using the high-octane fuel is another plus for the German Homare.