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The reason for me liking the "two V12's" approach is toHave them make a W24 instead?
I meant the general approach, not copying every ill thought out idiosyncracy of the historical inspiration.Use it but you have to use the real limitations.
Like regular fuel.
While the engines drove the props separately the engines were connected and rotated at the same speed. One supercharger at the back feed both engine blocks and that lead to a lot of problems, backfire in that duct/manifold tended blow off parts of the cowl.
You could not actually run the plane on one engine/prop if one engine failed so.....................is it one engine or two?
The reason for me liking the "two V12's" approach is to
- Avoid the need to develop a new engine, or for that matter tightly bolt two engines together and then worry about new and exciting vibration problems.
- Small frontal area.
The 18 cyl radials seem to me as the most realistic option.
I find it most interesting
Having two (short) crankshaft means these can be light while still being stiff (or, alternatively, can be very stiff and still not overweight), and power impulses from the air-fuel mixture explosions are 'spread' in a less punishing way than it will be the case with X16 or X24.
Nobody expects that an engine much more powerful than an ordinary V12 is without shortcomings, bigger frontal area and weight are certain things here. After all, we're expecting 1800-2000 HP from just a single engine, the 'no free lunch' rule applies as ever.
How good is a tandem V12 (V24?) as a practical engine for military aircraft installation?
Such a powerplant relocates the cockpit well back, sorta what happened with Curtiss XP-37 or Bell model 3 (for different reasons, but still - it makes F4U and Spitfire miracles of frontal visibility in comparison), and it also precludes any meaningful fuel tankage in the fuselage.
Yes. But with the caveat, as IIRC mentioned by SR6 in another thread, that it seems making a successful 18 cyl radial turned out to be significantly more complex than just slapping two 9 cyl radials together. Lots of manufacturers were successful with 5/7/9 cyl single row radials, quite a few had success with two row 14 cylinder ones too. But 18 cylinder ones that didn't run into lots of problems and were massively delayed were few and far between.
Indeed, as such maybe more practical as a nacelle installation on a big aircraft.
Or if using inverted V12's, put the cockpit between the engines, with the prop shaft going between the legs of the pilot?
But anyway, I digress, this seems off topic for this thread.
They might have had more time/money to work in the R-3350 if they hadn't flushed 6.5 million dollars (1940-41 money) and tens of thousands of man hours on the R-2160 project and started frantic catch up with the "new" R-3350.while Wright would've been well advised to keep the R-3350 at 2000 HP?
Or were they?Soviets were also doing well with M-71
The reason for the accident was a manufacturing defect in the carburetor. Three I-185s were successfully tested at the front. There were no complaints about the reliability of the M-71 engines during the tests. Klimov's M-107 had significantly more troubles at that time.From Wiki
"Based on the glowing report by the NII VVS (Nauchno-Issledovatel'skiy Institut Voyenno-Vozdushnykh Sil—Air Force Scientific Test Institute) in early 1942 preparations began to put the I-185 (M-71) into production. .................. It underwent manufacturer's tests between June and October and was submitted for the State acceptance tests on 18 November. However, flight testing was interrupted by the need to replace the engine between 17 December 1942 and 26 January 1943. The new engine failed the next day and the aircraft crashed on 27 January. Flight tests were ordered to be continued with the original prototypes to validate the range figures, but the first prototype crashed on 5 April, killing the pilot as he attempted a dead-stick landing."
So how about W18 inlines? Apart from a number of interwar of engines, the italians for instance were looking at the L.180 W18 project by WW2, which seems to use Asso cylinders in 3 banks. Would this configuration be made to work for other german, british etc. inlines? A 3 bank DB-601 derived engine seems to get us to the desired 1800-2000HP.
And iirc the soviets even had some Y inlines, i think 18 cylinders as well, have to look into that.
PS: Found the engine i was thinking of, the M-120
Поршневой авиационный двигатель М-120.
Поршневой авиационный двигатель М-120. :: Поршневой авиационный двигатель М-120. Разработчик: В.Я.Климов Страна: СССР Начало разработки: 1938 г. Постройка: 1940 г. В 1938 году под руководствомxn--80aafy5bs.xn--p1ai
W24 might be viable for: Allison (basically the V-3420 done early), RR (both from Peregrine and Merlin as part donors), Chrysler (made instead of the IV-2200), M-105, L.122 (with Italians still in liquid cooled business), HS12Y-51 (obviously requiring France to be still in the game). Granted, the W24 spin off from the Merlin will be one heavy engine and a bit on the wide side ( just like the V-3420 was), but with benefit of making much more than 2000 HP on 100 oct fuel even in 1941.
Upright engines don't have the problem of fuel+oil dripping down to the hot exhausts like the inverted types did.
Lighter engine should've been achieved with H16 spin offs, but only Merlin and V-1710 can compete here among the engines listed above. Shortcoming is that commonality between the V12s is much reduced. Engines that might be considered as starting points include DB 601 (H16 being less risky than the DB 606, with less power but shorter and with lower weight, so it can also be installed on smaller A/C), Jumo 211 (less risky than the 222), AM-35/38 (now this is one bulky and heavy, if very powerful engine), DB 603 (again bulky, heavy and powerful type, close to the DB 606 in that regard; less risky than X24 and W24 DB types).
The H16 Prince by Fairey was an historical example, even if the power was not as high as I've stipulated as required here.
Seeking more power, Forsyth investigated a 16-cylinder engine designated P.16 that displaced 2,078 cu in (34.1 L). A V-16 design was initially considered, but the configuration was changed over concerns regarding the engine's length combined with excessive torsional vibrations and stress of the long crankshaft. The P.16 configuration was switched to an H-16 with four banks of four cylinders. However, by switching to an H-24 configuration with four banks of six cylinders, a more powerful engine could be developed that would possess the same frontal area as the H-16. In fact, there is little evidence from primary sources that indicates a P.16 engine or an H-16 configuration were ever seriously considered.
24 cylinder engines means higher cost. We are back the the British not wanting to build the Whirlwind because it used two engines (12 cylinders each) ) but they were perfectly happy to build Typhoons/Tornadoes with one engine (24 cylinders)
Vulture, should have taken instead Merlin cylinders, reduce stroke to again about 46-47 litres, reduce rpm to a more sedate 2600-2700 or so to increase reliability, and voila, 2000 HP on 100 octane easy-peasy.
Sabre, well If the Vulture works then no need for it. On the other hand, If it still exists, then again forget about the fancy sleve valves and ridiculously high rpm, size it to at least 45 litres and reduce rpm to 3000 or less.
The Vulture had a 5.00 in (127 mm) bore and a 5.50 in (140 mm) stroke. The engine's total displacement was 2,591 cu in (42.47 L), and it had a takeoff rating of 1,800 hp (1,342 kW) at 3,200 rpm with 6 psi (.41 bar) of boost. At 3,000 rpm with 6 psi (.41 bar) of boost, the Vulture had a maximum rating of 1,845 hp (1,312 kW) at 5,000 ft (1,524 m) and 1,710 hp (1,223 kW) at 15,000 ft (4,572 m). At 2,850 rpm with 6 psi (.41 bar) of boost, the Vulture had an international rating of 1,780 hp (1,327 kW) at 4,000 ft (1,219 m) and 1,660 hp (1,237 kW) at 13,500 ft (4,115 m) and a maximum climb rating of 1,760 hp (1,312 kW) at 5,000 ft (1,524 m) and 1,640 hp (1,223 kW) at 15,000 ft (4,572 m). At 2,600 rpm with 5 psi (.34 bar) of boost, the engine had a maximum cruise rating of 1,540 hp (1,148 kW) in low gear and 1,460 hp (1,089 kW) in high gear. The Vulture was 87.2 in long, 35.8 in wide, and 42.3 in tall. The engine weighed 2,450 lb.
W engines in general seem to have a bit of an awkward shape when viewed from the front. Great if you for some reason want to have a sort-of triangular cross section of the fuselage. And as mention, routing of exhaust for the middle row seems a bit problematic, you obviously don't want to blow the exhaust straight into the windshield.So how about W18 inlines?
I don't see any challenge in people making 2-engined fighters, with 1000-1200 HP engines for 1941 - it was done many times.All of this just reinforces my view that, for 1941, the best chance to have the beast in service was a normal twin installation. Using the latest in existing production engines. A couple of 1,000bhp engines are easy to acquire and already work. Many are in the 1,200bhp class. Making more is probably easier than developing something new on 1941 fuels.
All hail the Rolls Royce Peregrine MkII Westland Whirlwind MkII.