Improve That Design: How Aircraft Could Have Been Made Better (1 Viewer)

[ThomasP]

Part of the A6M specification required the ability to escort bombers over long ranges. The A5M4 (effective ROA of ~300 miles with DT) was found deficient for escorting bombers over the ranges required during many of the missions occurring in the late-1930s operations.

 

[cherry blossom]

Coming back to Japanese engines, it is clear that Japan had very good engineers. However, they only had so many good engineers and they spread them too thinly. Japan had more engines types in production than most other countries. It is rather easy for us to tell them which designs to push and which ones to abandon but it was harder at the time. It also needed the Army and the Navy to agree on what to tell Mitsubishi and Nakajima to do.

Mitsubishi had three sizes of cylinder with two of the sizes offered in 14 and 18 cylinder versions. They also made experimental 22 cylinder and 28 cylinder radials and 24 cylinder liquid cooled H.

Nakajima also had three sizes of cylinder and made 14 and 18 cylinder radials using each cylinder (also the 9 cylinder Kotobuki and Hikari although these were probably not developed in WW2). Again there was interest in a 24 cylinder H and a 22 cylinder radial.

Going from development to production, Mitsubishi mass produced four radials during WW2, the 28l Zuisei, the 32l Kinsei, the 42l Kasei and the 54l Ha-104 (and tried to produce the MK9). Nakajima mass produced the 28l Sakae, the 36l Homare, the 37.5l Ha-5/Ha-41/Ha-109 and the 45l Mamoru (also the Kotobuki remained in production until 1943). For comparison, Pratt & Whitney produced the R-1830, the R-2000 and the R-2800 whilst Wright produced the R-1820, the R-2600 and the R-3350. BMW produced the BMW-132, the Bramo-323, the BMW-801 and the BMW-003. Daimler Benz produced the DB-601, 605 and 603 as well as the coupled DB-606 and 610. Rolls Royce produced the Peregrine, the Merlin, the Griffon and the Vulture as well as the Welland jet.

Thus there is a case that both Mitsubishi and Nakajima designed and produced more engines types than other comparable companies. Obviously simply listing the names does not prove the case. We could argue that Rolls Royce may have abandoned the Peregrine and the Vulture to focus on the Merlin and the Griffon but that the Merlin was extensively redesigned to give the Merlin 60 and Merlin 100 series. However, adding fuel injection and water injection to give the Kinsei 60 series and the Kasei 20 series was also a big step. Unfortunately for Japan it was quite a slow step as these were used in prototypes flying in December 1942, the Ki-46-III and the G4M2, but in both cases production built up slowly with Ki-46-IIs and G4M1s being produced throughout 1943. Also note that the Kasei was produced with contra-rotating propellers for the N1K1 and with a long extension shaft for the J2M.

 

[MiTasol]

Coming back to Japanese engines, it is clear that Japan had very good engineers. However, they only had so many good engineers and they spread them too thinly. Japan had more engines types in production than most other countries. It is rather easy for us to tell them which designs to push and which ones to abandon but it was harder at the time. It also needed the Army and the Navy to agree on what to tell Mitsubishi and Nakajima to do.

Mitsubishi had three sizes of cylinder with two of the sizes offered in 14 and 18 cylinder versions. They also made experimental 22 cylinder and 28 cylinder radials and 24 cylinder liquid cooled H.

Nakajima also had three sizes of cylinder and made 14 and 18 cylinder radials using each cylinder (also the 9 cylinder Kotobuki and Hikari although these were probably not developed in WW2). Again there was interest in a 24 cylinder H and a 22 cylinder radial.

Going from development to production, Mitsubishi mass produced four radials during WW2, the 28l Zuisei, the 32l Kinsei, the 42l Kasei and the 54l Ha-104 (and tried to produce the MK9). Nakajima mass produced the 28l Sakae, the 36l Homare, the 37.5l Ha-5/Ha-41/Ha-109 and the 45l Mamoru (also the Kotobuki remained in production until 1943). For comparison, Pratt & Whitney produced the R-1830, the R-2000 and the R-2800 whilst Wright produced the R-1820, the R-2600 and the R-3350. BMW produced the BMW-132, the Bramo-323, the BMW-801 and the BMW-003. Daimler Benz produced the DB-601, 605 and 603 as well as the coupled DB-606 and 610. Rolls Royce produced the Peregrine, the Merlin, the Griffon and the Vulture as well as the Welland jet.

Thus there is a case that both Mitsubishi and Nakajima designed and produced more engines types than other comparable companies. Obviously simply listing the names does not prove the case. We could argue that Rolls Royce may have abandoned the Peregrine and the Vulture to focus on the Merlin and the Griffon but that the Merlin was extensively redesigned to give the Merlin 60 and Merlin 100 series. However, adding fuel injection and water injection to give the Kinsei 60 series and the Kasei 20 series was also a big step. Unfortunately for Japan it was quite a slow step as these were used in prototypes flying in December 1942, the Ki-46-III and the G4M2, but in both cases production built up slowly with Ki-46-IIs and G4M1s being produced throughout 1943. Also note that the Kasei was produced with contra-rotating propellers for the N1K1 and with a long extension shaft for the J2M.

Pretty good summary however Pratt also produced the R-985 throughout the war and likewise Wright produced their R-975. Pratt was also still producing the R-1690 and R-2180 Hornet engines at the start of the war.

Like the Japanese Pratt, Rolls and Wright all dabbled in other engines (eg the Wright R-1300 started life in 42) and all did major redesigns of their main products. Unlike the Japanese they did however have Army and Navy, and RAF, who who cooperated with each other and who would not fund too many competing projects.

The 1938 R-1820 F52 series engines at 890hp were much heavier and drank far more fuel than the Sakae which was probably in pre-production testing at that time. The 1820 and 30 were engines that had been around for years by the beginning of ww2 whereas Mitsubishi and Nakajima only created their designs in the very late 30's. To give you a rough idea of where public knowledge of Japanese engine design and production stood in 1938 see Janes below.

 

[BobB]

Pretty good summary however Pratt also produced the R-985 throughout the war and likewise Wright produced their R-975. Pratt was also still producing the R-1690 and R-2180 Hornet engines at the start of the war.

Like the Japanese Pratt, Rolls and Wright all dabbled in other engines (eg the Wright R-1300 started life in 42) and all did major redesigns of their main products. Unlike the Japanese they did however have Army and Navy, and RAF, who who cooperated with each other and who would not fund too many competing projects.

The 1938 R-1820 F52 series engines at 890hp were much heavier and drank far more fuel than the Sakae which was probably in pre-production testing at that time. The 1820 and 30 were engines that had been around for years by the beginning of ww2 whereas Mitsubishi and Nakajima only created their designs in the very late 30's. To give you a rough idea of where public knowledge of Japanese engine design and production stood in 1938 see Janes below.
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P&W quit building single row engines after the US entered the war. Continental, Jacobs and I don't remember who else built R-985 & R-1340 The last US built R-985 were by Jacobs at a government owned plant near Pottstown, PA. P&W production of R-1830 peaked in 1943, then started dropping as Buick & Chevrolet R-1830 production hit their peak rate. Wright production of R-760/R-975(I don't have numbers for R-975 alone) peaked in 1942, then started dropping down to only 20 engines in December 1943. Continental took over R-975 production and continued building them into the 1950's. It made sense for P&W and Wright to get out of building engines that were not being further developed.

 

[SaparotRob]

Are any of these engines still being made? They must be getting scarce.

 

[XBe02Drvr]

Are any of these engines still being made? They must be getting scarce.

They're nearly indefinitely rebuildable and reworkable if anybody's willing to pay for it.

 

[ThomasP]

The last new-build R-1820 was produced in 1964. I think the R-1820 can claim the last new production of the engine types listed above?

 

[yulzari]

I imagine that if they redesigned the SBD's wing to fold (in any configuration), it would affect it's dive angle for the reason that once those massive dive brakes deploy, that would put considerable stress on the joints.

The issue with joints for folding is weight not strength. well designed folding joints are as strong as non folding wings but heavier to achieve this. After all, all wings are a conglomeration of joints arranged so as to keep the wings in the shape intended by the designer, folding wings merely have a few big ones that can swivel or be locked in place.

 

[MiTasol]

And a small fold at the tip like the A6M and Seafire weighs very little - plus is not affected by any of the stress that comes from deploying dive flaps.

 

[XBe02Drvr]

The last new-build R-1820 was produced in 1964. I think the R-1820 can claim the last new production of the engine types listed above?

Still in use on T28s, S2s, C1s, and C117s when I got out of the Navy in 1974. Clatterboxes, they always sounded like they were about to come apart at the seams.

 

[BobB]

The last new-build R-1820 was produced in 1964. I think the R-1820 can claim the last new production of the engine types listed above?

I've seen photos of industrial engines derived from the R-1820 which are apparently still in production. If you have a large mine out in the wilderness, you have a GE LM2500 (derived from CF6) turning out 30 MW power. A smaller operation might have the R-1820 derivative driving a generator. Either way, they may have a C-130 with a 3600 gallon tank in the cargo compartment flying in fuel for them.

 

[MiTasol]

Heli Niugini used to fly 4 tonnes of fuel in on sling loads with the Mil-8 helicopters to one gold mine. Early on they used the Mil-26 to sling load fuel in and gold out in shipping containers. The latter containers straight to the ship. Twenty six tonnes max load.

 

[Spindash64]

I've seen photos of industrial engines derived from the R-1820 which are apparently still in production. If you have a large mine out in the wilderness, you have a GE LM2500 (derived from CF6) turning out 30 MW power. A smaller operation might have the R-1820 derivative driving a generator. Either way, they may have a C-130 with a 3600 gallon tank in the cargo compartment flying in fuel for them.

Hell, I think there's folks still building parts for US engines specifically to keep warbirds in the air, so depending on how you conclude the Ship of Theseus paradox, the engine never went out of production at all

 

[Admiral Beez]

Are any of these engines still being made? They must be getting scarce.

I expect Curtiss and P&W radials have readily available or easy to fabricate spares and a small industry keeping them running for both commercial and museum/private aircraft.

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But with far fewer made, a Bristol sleeve valve radial likely doesn't. Though some give it a go, but not for commercial aircraft.

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[FLYBOYJ]

I expect Curtiss and P&W radials have readily available or easy to fabricate spares and a small industry keeping them running for both commercial and museum/private aircraft.

They don't - but companies with "Parts Manufacturing Approval" or approved Repair Stations may support older Curtiss and P&W products.

 

[XBe02Drvr]

Hell, I think there's folks still building parts for US engines specifically to keep warbirds in the air, so depending on how you conclude the Ship of Theseus paradox, the engine never went out of production at all

In 1938 the PZL company in Poland took out a license on the Wright R1820 engine, and I believe, continued manufacturing them right up til the end of the cold war.

 

[Shortround6]

In 1938 the PZL company in Poland took out a license on the Wright R1820 engine, and I believe, continued manufacturing them right up til the end of the cold war.

This gets a bit weird.

Poland may have taken out a license for A Wright R-1820 engine 1938 but which one? There are significant differences between the different models.

In 1960 the USSR had Poland start building ASh-62IR as the ASz-62 for Soviet helicopters, agricultural aircraft and later, DHC-3s and DC-3s.

Since the ASh-62 started as the M-62 which was a modified (?) M-25 which was a licensed Wright R-1820-F3 so there is quite a history of Soviet production of the R-1820 and "improvements" dating back to 1933 and talks starting earlier.

Soviet engines were supposed to have been converted to metric measurements/standards (Russian book) in the early/mid 30s.

There is no doubt that Poland built R-1820s. The question is which path was followed?
There is little or no record in the West of Poland building R-1820s in the 40s or 50s. Or indeed much of anything for piston engines until the Mid-late 50s with the WSK WN-3 engine.

 

[Admiral Beez]

A MkII Spitfire or Bf109E-4

Not for their carriers, I don't think. I think something more like the F4F Wildcat.

 

[MIflyer]

I expect Curtiss and P&W radials have readily available or easy to fabricate spares

Well, no, and in some cases parts have been getting scarce for some time.

I recall that around 1979 I read that a company was dealing with the shortage of replacement cylinders for R-1340 engines used in crop dusters and T-6's by taking the much more plentiful R-2800 cylinders and converting them for use in R-1340's. They shortened the cylinders and did what else was needed for the R-1340 use. Note that the R-2800 literally was based on a double stack of R-1340 cylinders, an engine that already had been in use in various applications for almost a decade. Aside from being able to use cylinders that had not been rebuilt over and over, the R-2800 cylinders were based on more advanced technology than the R-1340, giving a more robust engine.

The R-670 is one of the more popular radials still in use, in Stearman and Waco biplanes. Versions of that engine were also used in M3 Stuart tanks and various landing craft. A man I knew rebuilt R-670 engines by taking the cylinders from the non-aeronautical engines. He could not use the non-aeronautical pistons because they were not suitable; one type was forged and the other was cast. Too late, I realized that he had been hauling the pistons down to the scrapyard and selling them for the value of the aluminum. It suddenly struck me that I could have given him $1.00 each for them, far more than he actually received, mounted them on a suitable wood base, added a plaque describing them as a genuine Stuart tank engine part, and sold them to history buffs for, say, $19.95.

 

[XBe02Drvr]

The R-670 is one of the more popular radials still in use, in Stearman and Waco biplanes. Versions of that engine were also used in M3 Stuart tanks and various landing craft. A man I knew rebuilt R-670 engines by taking the cylinders from the non-aeronautical engines.

We had one of those "resurrected" tank engines at mech school. It was our first strip, rebuild, and run engine before moving on to the R1820, then the Lycoming GO480. As a school run by former Mohawk Airlines victims of the Allegheny takeover, it was clear from that sequence where their priorities lay. They loved the old CV440s and Martin 404s and regarded kerosene burners with distaste.