Advantages & Disadvantages: Nations & Doctrine, Aircraft and Technology of WWII

[wuzak]

How so?

Basically radiators were often just hung in the breeze.

Which was my point: The demand in the civil industry decreased as the NACA cowling came online, leaving most of the demand for inlines in the military applications or airships possibly.

The NACA cowling didn't change some aspects of air-cooled engines which made them attractive to commercial aviation - simplicity and lower maintenance requirements.

Because the demand ran low, so to did research and supply, and this reduced the developments of inlines, new ones at least, to a crawl.
Yeah, but the NACA cowling wasn't really shaped to optimize this effect, though as time would go on this would change: Aircraft that seemed to produce a shape better suited would be the Fw 190 prototype, the Lavochkin La-5, and the F7F prototype.

The military did fund extensive research on in-line engines. They even came up with their own cylinder design - the hyper cylinder.

The Fw 190 was the game changer for radial engine installation designs. I think the others, like the Tempest II and Fury/Sea Fury, developed from there.

Also, proponents of air-cooled engine installations seem to forget that it is entirely possible to do the same, or similar, with radiators as was down with radials, with the added advantage of having a less tortuous path for the air.

Improvements in cooling design tended to come with new aircraft designs. Designs in production tended to not get the newest and latest trends, as changing production would be costly in terms of number of aircraft produced.

 

[swampyankee]

If I remember my readings, early liquid cooled engines used shell-and-tube heat exchangers, which require more area than plate-fin HXs, and are more prone to flow separation, water requires lower temperatures, forcing larger HX area, radiator ducting design wasn't understood, resulting in high cooling drag.

Have you ever heard of Lamblin radiators?

 

[swampyankee]

Basically radiators were often just hung in the breeze.

The NACA cowling didn't change some aspects of air-cooled engines which made them attractive to commercial aviation - simplicity and lower maintenance requirements.




The military did fund extensive research on in-line engines. They even came up with their own cylinder design - the hyper cylinder.

The Fw 190 was the game changer for radial engine installation designs. I think the others, like the Tempest II and Fury/Sea Fury, developed from there.

Also, proponents of air-cooled engine installations seem to forget that it is entirely possible to do the same, or similar, with radiators as was down with radials, with the added advantage of having a less tortuous path for the air.

Improvements in cooling design tended to come with new aircraft designs. Designs in production tended to not get the newest and latest trends, as changing production would be costly in terms of number of aircraft produced.

I think one could argue that.I think that the US commercial companies beat them to it. Of course, I also get very tired of "the Germans were smarter than everybody" meme.

 

[Shortround6]

The NACA cowling in 1930 was competing against water cooled engines that did not use pressurized systems. With the introduction of glycol (100% or close to it) radiators could be made much smaller than using pure water with the same cooling power. US tried to push to 300 degrees F coolant temp but that was too high. Glycol has a few problems of it's own, like being able to leak through seams that are water tight, Mixtures of water/glycol like 50/50 or 70/30 cool almost as well as pure glycol and leak less, they also have higher boiling points than pure water.
SO in about 10-11 years the "liquid" cooled engines also went through 3 different types of cooling fluid. Different radiator matrix's and some really different duct work (or even the introduction of a duct). They certainly weren't standing still. It is this progress that makes statements like "once the NACA cowl was invented the air cooled engine was equal to the liquid cooled" absurd. The NACA went through several stages during the 30s. the Liquid cooling systems went through several stages. ANd air cooled cylinders doubled (or more) the the amount of fin area per cylinder from 1930 to 1940 meaning they cooled much better with less air flowing through the cowling.
Blanket statements do a disservice to all those involved.

 

[nuuumannn]

If I recall they'd thought of ideas even in the 1930's.

The first Russian jet engine was designed in 1937 by A.M. Lyulka, although he didn't begin working on hardware until around late 1939, 1940, as the RD-1, with around combustion chamber and turbine section undergoing testing a year later. The German invasion put paid to further development until 1944. Independent of anyone else's research, Lyulka proposed high bypass engine for which he received certification from Moscow, and afterburners.

I could imagine, plus the British gave them the Nene...

...and Derwent, in 1947. It is interesting to note, however, that the VK-1 engine, which included design features from the Nene was actually begun before the British technology arrived in Russia, also the Russians had sent people to Britain after the war in an attempt to buy jet fighters, including Klimov and Mikoyan, obviously to gain knowledge of their capabilities and design.

No, but we did value the idea very early on

But to say that other nations didn't is not true. This link to Wiki mentions a couple of entries on altitude records, including the 1933 Everest expedition using Westland biplanes powered by Bristol engines. The Bristol 138 had supercharged Pegasus for its altitude performance: Bristol Type 138 - Wikipedia

German aircraft here; Albatros H.1, although unsuccessful was an attempt in the immediate aftermath of the Great War: Polish Aviation Museum Cracow

Henschel Hs 128: Henschel Hs 128

Which led to Hs 130: Henschel Hs 130 - Wikipedia

That's a good point, but when you look at the P-38 it was high altitude off the bat.

Yet, the most common US fighters at the time WW2 kicked off, 1939 not 1941, were easily outperformed at altitude by their European contemporaries. The P-40 and P-39 were no match for the Bf 109 and Supermarine Spitfire at height in 1939/1940.

 

[Shortround6]

Yet, the most common US fighters at the time WW2 kicked off, 1939 not 1941, were easily outperformed at altitude by their European contemporaries. The P-40 and P-39 were no match for the Bf 109 and Supermarine Spitfire at height in 1939/1940.

While what you say is quite true, many people attribute this "effect" to the wrong "cause"..........or causes.

For instance the altitude the 3 engines made power at were;
1. Merlin III........16,250ft...1030hp.
2. DB 601A-1.....14,764ft...1006hp
3. Allison C-15...14,300ft... 1040hp

Obviously the Merlin has an advantage but perhaps not as much as imagined. The DB 601 has no advantage to speak of over the Allison. The answer must lie somewhere other than the engine/supercharger technology.

The answer is not hard to find. It is the work the engine was expected to perform, specifically the weight the it was lugging around.
1. Spitire I..........6125lbs or bit more as equipped during the BoB.
2. 109E-3...........5750lbs,, varies by source and this is about the heaviest (no guarantee)
3. P-40...............6787lbs or more The P-40Bs and Cs actually went 7350-7500lbs even with less than full fuel tanks.

I would imagine the DB engine would have struggled if was carrying around an extra 28% of weight.
I would also note that the Larger, Heavier P-40 was faster than the 109E so claims of how much more advanced the 109E was must be taken with a large dose of salt. Sticking a large engine in a small plane is hardly a sign of sophisticated design even if it is effective.

 

[nuuumannn]

The answer is not hard to find.

Yep, sure isn't. No disrespect to either the P-40 or the P-39, both aircraft having enjoyed conspicuous combat careers during the war, but they were out performed in the European theatre at its beginning.

 

[swampyankee]

Yep, sure isn't. No disrespect to either the P-40 or the P-39, both aircraft having enjoyed conspicuous combat careers during the war, but they were out performed in the European theatre at its beginning.

Although it's interesting that the Soviets thought so well of the P-39. Low-down, it seems to have been quite decent. Reputedly,the P-40 was a sweet airplane to fly, which means that low-time pilots would be able to get much more out of the aircraft, and generally have a better chance to become high-time pilots by avoiding landing accidents, uncontrolled departures, and unwillingness to pull that turn just a little tighter or hold that dive just a little longer.

 

[nuuumannn]

Although it's interesting that the Soviets thought so well of the P-39. Low-down, it seems to have been quite decent.

I guess some of it boils down to perspective, the P-39 had reliability issues to begin with, but almost all who flew it said that it had good handling and good performance low down, which is where the Russian front was being fought. It was in 1939/40 a modern fighter, but it just couldn't perform at altitude.

The P-40 was well liked by the Aussies and Kiwis who flew it in their respective air forces and I don't think there are too many accounts of pilots saying it was a dog, it just wasn't up to the standard of the likes of the Fw 190, Bf 109F etc in terms of performance.

 

[Zipper730]

I have a strange question: Had the USAAF developed more twin-stage superchargers, would it have been possible to mass produce turbos?

 

[tyrodtom]

I have a strange question: Had the USAAF developed more twin-stage superchargers, would it have been possible to mass produce turbos?

What is your definition of mass production?
With just the B-17, B-24, P-47, and P-38, you got over 150,000 turbos produced, not counting spares.
Not all the same turbos, but still a lots of turbos

 

[Shortround6]

We may be having a problem with translation. Every US WW II aircraft that used a turbo was a two stage system.
However it is common usage to refer to turbo systems as just turbocharged while referring to systems that used a mechanically driven auxiliary or extra stage in addition to the normal engine mounted supercharger as "two-stage". There were three different mechanical systems Used by US aircraft in WW II. The P & W system in which the engine supercharger always ran a single fixed gear supercharger and was feed by an auxiliary supercharger that had two speeds plus neutral. SO the Auxiliary supercharger could either be turned totally off and air brought in through auxiliary doors or air flowed through the un-powered supercharger and slowly windmilled the impeller. At a certain altitude the impeller was clutched in for better altitude performance and at a even higher altitude the higher gear was selected.
The US Merlins worked like the British ones. Both impellers were on a common shaft and this shaft was driven by a two speed gear set up. Both impellers always turned the same speed, either low speed or high speed. The Allison engine used in the P-63 used a single speed supercharger on the back of the engine and the auxiliary impeller was in a separate housing behind the engine with a driveshaft -hydraulic drive system connecting to the engine. The drive system was Infinitely variable between the high and low limits. no peaks or valleys in the power curve.
The F4F-3, F4F-4 and FM-1 Wildcats used the P & W system as did the F4U Corsair and the F6F Hellcat. So did the P-61.
P-51s from the B model on Used the Merlin system. P-63 King cobras used the Allison system. These are for production aircraft.

For the USAAF the ONLY fighters not to use two-stage systems were the P-39 and P-40.

 

[Zipper730]

What is your definition of mass production?

Enough to equip whole types of aircraft. For example in the US we had developed planes like the B-17, B-24, B-29, P-38, and P-47 that were turbocharger equipped.

The demand for them lead to R&D and supply, and while I think the USAAF had a predilection for them, and didn't seem to view a twin-stage supercharger as being all that useful most of the time: I'm curious if they had persued the twin-stage supercharger somewhat more, if the R&D for turbos would have been affected.

The P-38 early on in the war would have been hard pressed to have done as well without one; the B-17, and B-24 wouldn't have been as survivable if they'd have flown at 15,000 feet instead of 25,000 feet...

We may be having a problem with translation. Every US WW II aircraft that used a turbo was a two stage system.

Yes, there was the mechanically driven supercharger, and the turbocharger as well

However it is common usage to refer to turbo systems as just turbocharged while referring to systems that used a mechanically driven auxiliary or extra stage in addition to the normal engine mounted supercharger as "two-stage".

No problems so far, I understand you perfectly...

There were three different mechanical systems Used by US aircraft in WW II. The P & W system in which the engine supercharger always ran a single fixed gear supercharger and was feed by an auxiliary supercharger that had two speeds plus neutral.

Now, that's something I didn't know: I was under the impression that the engine supercharger had two speeds, with the auxiliary supercharger idling at neutral-blower, then clutched into low & high blower.

SO the Auxiliary supercharger could either be turned totally off and air brought in through auxiliary doors or air flowed through the un-powered supercharger and slowly windmilled the impeller.

Did windmilling offer any advantage?

The US Merlins worked like the British ones. Both impellers were on a common shaft and this shaft was driven by a two speed gear set up. Both impellers always turned the same speed, either low speed or high speed.

I understand

The Allison engine used in the P-63 used a single speed supercharger on the back of the engine and the auxiliary impeller was in a separate housing behind the engine with a driveshaft -hydraulic drive system connecting to the engine. The drive system was Infinitely variable between the high and low limits. no peaks or valleys in the power curve.

Variable speed...

The F4F-3, F4F-4 and FM-1 Wildcats used the P & W system as did the F4U Corsair and the F6F Hellcat. So did the P-61.

For the USAAF the ONLY fighters not to use two-stage systems were the P-39 and P-40.

From what I've heard the P-40 was developed because of the P-37, and a desire to avoid the complexity of a turbocharger; the P-39 used a single-stage layout because the turbo it was to use was inadequate. The P-61 seemed the only one I know of to be consciously chosen from the start as a twin-stage supercharger arrangement that was NOT a turbocharger...

 

[wuzak]

From what I've heard the P-40 was developed because of the P-37, and a desire to avoid the complexity of a turbocharger; the P-39 used a single-stage layout because the turbo it was to use was inadequate. The P-61 seemed the only one I know of to be consciously chosen from the start as a twin-stage supercharger arrangement that was NOT a turobcharger...

The turbocharger in the XP-37 was especially prone to failure, and the improved model in the YP-37 was little better.

The X/YP-37 was also not very well laid out because it had all of the cooling and intercooling between the engine and the pilot, meaning that the latter was quite a way aft, making it slightly impractical.

The YP-37 also did not perform as well as expected, and was, in fact, slower than the P-40.

The XP-39 installation was a dog's breakfast.

 

[swampyankee]

I guess some of it boils down to perspective, the P-39 had reliability issues to begin with, but almost all who flew it said that it had good handling and good performance low down, which is where the Russian front was being fought. It was in 1939/40 a modern fighter, but it just couldn't perform at altitude.

The P-40 was well liked by the Aussies and Kiwis who flew it in their respective air forces and I don't think there are too many accounts of pilots saying it was a dog, it just wasn't up to the standard of the likes of the Fw 190, Bf 109F etc in terms of performance.

I think that the record shows that, below about 15,000 ft, the P-40 was up to the "standards" of the Bf109s that it met in combat. I also think that the record of, say Spitfires and Hurricanes, vs IJN and IJAAF aircraft tends to show that neither the Luftwaffe's aircraft or pilots were as good as their legend.

 

[Zipper730]

The turbocharger in the XP-37 was especially prone to failure, and the improved model in the YP-37 was little better.

What made it prone to failure?

The X/YP-37 was also not very well laid out because it had all of the cooling and intercooling between the engine and the pilot, meaning that the latter was quite a way aft, making it slightly impractical.

What better options could have been used?

The YP-37 also did not perform as well as expected, and was, in fact, slower than the P-40.

That's true...

 

[wuzak]

What made it prone to failure?

It was an immature design.

What better options could have been used?

Not having the intercooler and radiator mounted between engine and pilot would be a start - they could have been mounted ahead of the turbo, under the spinner.

 

[Zipper730]

message deleted

 

[Shortround6]

Table of turbo characteristics: http://www.enginehistory.org/Turbochargers/GETurbochargerData.jpg

Now for comparisons sake, the intercooler and ducting on the B-24, a 1200hp engine,

Large rectangular finned box on the right is the intercooler. Copper unit is the oil cooler. The XP-37 needs a coolant radiator to boot.
Sticking turbo systems in skinny single engine fighters was not easy.

 

[Old Wizard]