Re-engined planes

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How about a Kawasaki Ki-61-II with a Daimler Benz DB605D from a Me 109K?

Forget that logistically this never would have worked, but here we would have a nice slick airframe with enough engine power to kill just about anything on the Allied side in the Pacific.
The engine installation should be very easy assuming an adequate supply of engines....
....and good consumables such as fuel, spark plugs, etc.

- Ivan.
 
Regarding the rather long discussion revolving around the Wright R-2600 engine and how it was never installed in a fighter:
Remember the prototype Grumman Hellcat used a R-2600 which didn't offer enough performance and was promply replaced with the P&W R-2800.

- Ivan.
 
I can't remember what forum it was on - but I have seen a photo of a Beaufighter (Australian I think) with R-2600 engines - looked quite good.

Gloster F.5/34 prototype flew with 840 hp Mercury - which would be the best option
- (A) more powerful Mercury XV 905 hp (as per Blenheim IV), and Mercury 30 950 hp (as per Blenheim V; or
- (B) R-1830 Twin-Wasp higher power; or,
- (C) Bristol Taurus a narrower engine, but although better than the Mercury in output reliability might be in question; or the French option
- (D) Gnome-Rhone 14N - initially at 970 hp then went up I believe to 1,080 hp
 
Some very nice alternative concept blueprint arts, but I wonder if anyone has made this suggestion...
Could all the created/edited or fictional arts should be tagged as such to prevent future mis-identification of these creations as real aircraft concepts/blueprints/sideviews etc, as some of them seem to keep only one of their orignal model identification designations/names/numbers.

Who would know any different if in 50+ years technological changes and or a calamity(../ies) meant that only a portion of remaining data was the fictions in this thread; unlikely as it maybe, no one can predict that far what will happen apart from many what could happen.

Just a thought.
 
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The R-2600 that powered 1st Hellcat have had several thing going against it. 1st will be that, even as a 2-stage engine version, was to power a 6-7 ton fighter. No can do with 1700 HP, at least not satisfactory. 2nd would ne that, even as the 'plain vanilla' R-2600 was developed earlier than similar R-2800, Pratt Whitney have probably had a lead in a development of 2-stage superchargers.
For a fighter to make sense to be powered with R-2600, it need to use early military version 1st (1600 HP for TO), then switch to 1750 HP version from early 1941 on. Need to be deployed, say, from late 1940 in RAF CW units, and then, as availability allows, in different US fighter units. The fighter also need to be reasonably small (220-270 sq ft, depending whether we talk about land- or CV-based A/C - hence my drumming of the P-36/40 with that engine), and not to have 300-340 sq ft wing like Hellcat and Corsair have had.


G&R version would look fine for, say, Poland, if they can get that before war started. For the British, the Taurus, for CW license production Twin Wasp. Maybe also the Cyclone?
 

I'll bet controlling the relationship between the propulsion engines' demand for air and the compressor-engine set's supply of air was easy to solve. And, of course, it would be absolutely easy-peasy to have low-loss, leak-free ductwork connecting the engines to the compressor.

Neglecting that, I think that the benefits of having a dedicated engine driving a compressor to be shared among all the propulsion engines is shown by the number of aircraft produced using that scheme. Leaving aside the fact that it's a single point of failure, the dedicated engine/compressor set and its required ductwork is going to be heavy and take up a lot of volume, probably heavier than individual engine-driven compressors, and certainly taking up much more volume in the wings and fuselage.

In any case, if I really wanted an ultra-high altitude, piston-engined aircraft, one could use two-stage turbocharging. Indeed, there is a modern project for an ultra-high altitude aircraft which uses a three-stage turbocharger, NASA's Perseus B (NASA Armstrong Fact Sheet: Perseus B Remotely Piloted Aircraft | NASA).
 

So if I understand you correctly: The R-2600 with a Military Rating of 1700 HP is insufficient to power a big fighter like the Hellcat, but the R-2800 with a Military Rating of 1800 HP (from the Pilot's Manual) is quite suitable?

Keep in mind that aircraft are very seldom designed without a requirement. The US military didn't believe in minimalist aircraft. They had specifically gone away from the radial engined P-36 to the P-40 series to get the improved aerodynamics of an inline. The inline installation was significantly heavier but they were willing to sacrifice climb and maneuverability to get just a bit of extra speed. I don't see the Army ever agreeing to go back to the equivalent of a P-36 with a bigger engine.

The Navy even with the Wildcat wanted good altitude performance even if the battles were happening at low altitude which is why they kept using the R-1830 instead of the R-1820 engines until the FM-2 which was never considered a first line fighter. This is certainly a rehash of the earlier conversation, but the R-2600 never had that altitude performance.

- Ivan.
 

Don't think they lost anything in climb with the P-40 compared to the P-36.
 
The 1st problem with the R-2600 was that was actually slightly larger in diameter than the R-2800. Not enough that you could pick up the difference in a photo of the plane using the engine but it was there.

Wiki; " The Cyclone-powered XF6F-1 (02981) first flew on 26 June 1942,"

By which time P&W had built about 120 two stage 2000hp R-2800s and about 2200 single stage 2000hp R-2800s, this doesn't count Ford.

The " just a bit of extra speed" was more like 30-40mph by the time they were done. Of course they then added all kinds of 'stuff' to the P-40 and slowed it down again but try adding the same amount of "stuff" to a P-36 and see what happens

One reason the Wildcat could go to the Cyclone in the FM-2 was that not only did it have 100-150 more HP for take-off than the Twin Wasp but they were running the new engine 100rpm (and 200 rpm for take-off) faster than the old Cyclones AND had a NEW supercharger. The FM-2 Wildcat engine could give 1000hp at 17,000ft compared to the older Cyclone giving 1000hp at 13,500ft. It kind of split the difference in altitude performance between the old Cyclone and the Two stage R-1830 while weighing about 150lbs less and that doesn't include the inter coolers or ducting.
 
For some reason, the mass produced versions R-2600 fell short in rated altitude, even in comparison with foreign engines, such as the BMW 801, which also used a single stage supercharger. There was one version with a turbosupercharger, but this seems to have been unsuccessful.

Aside from this, the R-2600 probably had more faults than the R-2800 if the following link is anything to go by

http://www.enginehistory.org/Wright/R-2600/R-2600CaseHx.shtml
 
tomo pauk said:
Re: Gloster f.5/34

G&R version would look fine for, say, Poland, if they can get that before war started. For the British, the Taurus, for CW license production Twin Wasp. Maybe also the Cyclone?
Click to expand...

If the prototype is built earlier, Countries that already license produce the Mercury may be interested e.g. Sweden Finland, Poland is interesting - P11c had a Mercury (earlier version), the PZL P.50 was to have the 840 hp Mercury, whilst the P.24 had the Gnome-Rhone 14N.

Which brings an interesting image of the Luftwaffe facing not P.24s but Polish Gloster monoplane fighters - they'll still get beat, but they'll take a few more with them, and they may be more readily accepted by the RAF !!
 
Ivan1GFP said:
So if I understand you correctly: The R-2600 with a Military Rating of 1700 HP is insufficient to power a big fighter like the Hellcat, but the R-2800 with a Military Rating of 1800 HP (from the Pilot's Manual) is quite suitable?
Click to expand...

Military and take off power was 2000 HP for Hellcat's R-2800, at really low altitudes. Same regimes for the R-2600: 1750 HP; maybe it was only 1700 for the 2-stage version used on 1st Hellcat?


The Army fighter 'contest' of 1939 included several radial-engined fighters too, specifically from Seversky. P-40 won, because it offered the best performance (combined with availability for the Army to have plenty of those in reasonable time), not because it was powered by an V-12.


The R-2600 certainly did not have had that great hi-alt performance, but then it was vastly better under 15000 ft; some 30% greater under 12000 ft. Above 18-19000 ft, it was still offering some 10% more power than a two stage R-1830, and it was considerably more powerful than a single-stage R-1830 that a good number of F4Fs got.


The main culprit for non-stellar hi-alt performace probably lays in it's small supercharger - 11 in diameter, vs. 13 in for the BMW-801 and Hercules; some Hercules engines have had 12 in S/C installed. Other thing was it's RPM, 2600 vs BMW's 2700 and Hercules with 2800 RPM.
We can also note that advantage the BMW-801C* (and the restricted 801D?) possessed against the R-2600-13 was some 50 HP at 15100 ft - 1361 HP (1380 PS) vs 1310. BMW installation was a more streamlined affair, though, with a better layout of exhaust stacks. The duration of that power was 3 min for the BMW, vs. 5 for the R-2600.

*max RPM was only 2550 in second S/C gear?

Aside from this, the R-2600 probably had more faults than the R-2800 if the following link is anything to go by

R-2600 Case History
Click to expand...

Yep, too bad some people didn't ended in jail, or worse.
 
A few things to consider about the R-2600.
Cooling of air cooled engines was not as well understood in the mid/late 30s as it was just a few years later. Things changed rapidly. The R-2600 may have been designed as much for commercial transport use as for military (especially fighter) use. The Army sure wasn't buying very much of anything from 1936 until the Spring of 1939. The R-2600 was in low level production in March of 1938, over a year before the the Army 1939 fighter trials. First use was the Boeing 314 Flying boat. Max power at sea level and a few thousand ft was much more important than high altitude performance. The smallest supercharger that will give the needed boost at sea level (or low altitude airports) means more power to the propeller for the same power generated in the cylinders.
Power generated in the cylinders governs the cooling load/problem. Also the weight/strength of the engine to handle the loads.
P W started later and P W didn't like big cylinders after they got burned, literally, with the Hornet "B" 9 cylinder engine (R-1860), which had cooling problems including melted pistons. Smaller cylinders offer better cooling because there is more cylinder wall per unit of volume.
The AAC (Army Air Corp) thought air cooled engines wouldn't work for turbo-charged high altitude bombers and while they were proven wrong it took a lot of work with finning and baffling.
And here you hit one of the snags with the R-2600 as a fighter engine. It is about the same diameter as a Cyclone 9 or at least much closer than the the R-1830 so that is a better starting point. Then we have the cooling problem.



Granted this is just a single case but please note that for a 1600hp engine the thermal losses are worth 1020hp. Basically going from a 1200hp engine to a 1600hp engine means you have 33% more heat to get rid of and you need 33% more airflow though the cowl or radiators or oil coolers. Some of your extra power is going to the extra cooling drag, certainly not all and you are going to see a performance increase, just not as much as the 33% increase in power implies. Also please note that 140hp to drive the supercharger for a 1600hp engine is on the low side. Using a higher gear ratio to improve altitude performance means more power to the supercharger and less to the propeller percentage wise but changes the cooling load hardly at all.

Using two-stage superchargers or turbos makes thing even worse at high altitudes. In the original engine (single speed or two speed) the power falls off with altitude as not as much fuel/air is being burned in the cylinders. Of course the thinner air doesn't cool as well either even though it is colder for a bigger temp difference. Going to a two stage supercharger raises the power needed to drive the supercharger/s you get more to the prop at the higher altitudes but you have raised the heat load, can the original cooling system (and on an air cooled engine a large part of that is the number/shape/size of the fins) handle this higher load in the thin air? You also have the problem of the higher intake charge temperature. Temperature of the intake charge flows through the engine, raise the intake temperature by 100 degrees and the exhaust temperature will be about 100 degrees hotter as will the temperature anywhere in-between including the combustion chamber. Those fins that worked just fine at 3,000ft and 70 degrees temperature may not handle the load at 23,000ft and 100+ intake temperature inspite of the much cooler air (you have roughly 1/2 the mass of air passing the fins). The Turbo adds a bit to the problem in that the exhaust is slightly restricted and the exhaust valve/seat/guide area may run a bit hotter.
ALL of these problems can be cured but it often took new head casting/forging/machining operations, new cylinder barrel fins, new baffles, etc. which all took time to design and try out and find the best (cheapest and quickest) answer. Please note that Wright redesigned the entire engine to get the 1900hp 'version' which was hardly cheap or quick
 
Another take on one of the inspirations here, namely the P-38: the nightfighter, with two turbocharged R-1830s. The radios radar (re)located in the booms, approx. at the area once the Prestone coolers were - in order to compensate for that lost weight. Second crew member, hopefully in a more neat accommodation than as it was with the P-38M. Northrop gets to build these? Not a 400 mph nightfighter, but it should be good for 380 - a bit faster than the Black Widow?
 
The R-2600 was a good bomber or transport engine as it was designed to give good power for weight at low altitude. The early versions were rated variously on 90-91 or 95 octane fuels and with the coming of 100 octane (american) the allowable power did NOT go up. This may be a clue
Many of the early versions used single speed superchargers with very low critical altitudes. Think Merlin VIII
What did happen was that the critical altitude improved, better fuel allowed for more compression in the supercharger compared to outside air but max boost held the same.
The GR-2600-A-2B using 91 0ctane and a blower ratio of 7.0:1 was rated at 1600hp for take-off, 1600hp Military at 1500ft (yes 1500ft) and max continuous of 1350hp at 5800ft.
The GR-2600-A-2A using 100 0ctane and a blower ratio of 7.0:1 was rated at 1600hp for take-off, 1600hp Military at 1500ft (yes 1500ft) and max continuous of 1350hp at 6200ft.

Adding the two speed drive helped things out a bit.
The GR-2600-A-5B using 91 0ctane and a blower ratio of 7.14:1 was rated at 1600hp for take-off, 1600hp Military at 1000ft (yes 1000ft) and max continuous of 1350hp at 5000ft. Using the 10.0:1 high gear gave 1400hp Military at 10,000ft and 1275hp max continuous at 11500ft.
The GR-2600-A-5B using 100 0ctane and a blower ratio of 7.14:1 was rated at 1600hp for take-off, 1600hp Military at 1500ft (back to 1500ft) and max continuous of 1350 hp at 5000ft. Using the 10.0:1 high gear gave 1400hp Military at 11,500ft and 1275hp max continuous at 12,000ft.

Wright had started work on an improved R-2600 (the 1700hp version) in 1938 but it would not run until Nov 1939 and entered production in June of 1941, Only 441 were built in 1941. This has much better prospects as a fighter engine but is a bit late in timing as it comes between The P W R-2800 A rated at 1500hp Military at 14,000ft and the R-2800 B rated at 1600hp Military at 13,500ft.

The GR-2600-B2 using 100 0ctane and a blower ratio of 7.06:1 was rated at 1700hp for take-off, 1700hp Military at 4100ft (yes 4100ft) and max continuous of 1500 hp at 6,700ft. Using the 10.02:1 high gear gave 1450hp Military at 14,100ft and 1350hp max continuous at 15,000ft.

.
 
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http://zenoswarbirdvideos.com/Images/B-24/B24OL.gif

This one is a real can of worms. SOOOO much depends on the drag of the R-1830 installation. Throw in the fact that the R-1830 ONLY exceeds 1200hp per engine at some point in 1943 in prototype aircraft (although a higher critical altitude for 1200hp was achieved earlier.) The R-1830 eventually hit 1350hp at 30,000ft in the B-24N production version. Please note there is NO WEP rating. 1350hp from sea level to 30,000ft. By the time the R-1830 gets to 1350hp the Allison is giving 1600hp WEP. I have no idea how big the inter-coolers on the B-24 were.

One of about 10-12 planes with the 1350hp turbo R-1830;



As for replacing the P-61? The radar used in the P-61 weighed about twice as much as the radar used in the P-38. It had about twice the range depending on target and it could search a 180 degree arc vs the 120 degree cone of the P-38 radar.

Picture of P-61 radar antenna:



One reason the 20mm cannon were in the belly of the the P-61 with that pregnant look

 
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