Engine choices for P-51 mustang ?

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nuuumannn said:
No, definitely not a better option. It had lower power output than the Allison and it was not produced by either the USA or Britain, so, bad idea. The Mustang would have been slower and had poorer performance with an engine that no one wanted.
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There is no better choice than the RR Merlin. But if the Hispano-Suiza 12Y was pushed upon us, it could be worked over into the more powerful Hispano-Suiza 12Z. And earlier on, the Soviets worked over the Hispano-Suiza 12Y to get to the Klimov VK-107. Other Hispano-Suiza products were produced by the Allies under license, including the HS.404 cannon produced by International Harvester.

Interestingly, Mitsubishi had acquired a license in 1935 for Hispano-Suiza engines, in this case a W-18.
 
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Admiral Beez said:
here is no better choice than the RR Merlin. But if the Hispano-Suiza 12Y was pushed upon us, it could be worked over into the more powerful Hispano-Suiza 12Z. And earlier on, the Soviets worked over the Hispano-Suiza 12Y to get to the Klimov VK-107.
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In both cases they were trying to get the best engine they could while still retaining much of the production tooling.
The US has no Hispano-Suiza production tooling to save. Build a decent engine to begin with new tooling/techniques and save years of sweat/time/frustration trying to put lipstick on a pig.
Forcing the adoption the H-S engine should have been met with guns and bayonets as treason and/or sabotage. Simple profiteering does not cover it.
 
For being seemingly the worst v-12 aero engine of ww2 (worse than a Peregrine?), the Hispano-Suiza 12Y and its derivatives were widely used, especially by the Soviets. Why did France choose a Spanish company's engine over making one of their own? And if you're France and going to license produce or source a foreign v-12, why not ask for the Merlin?
 

The 12Y was a French engine, built by the French arm of the Hispano-Suiza company.
 
The French did try, the first contact of Ford with Rolls Royce was for Ford to build Merlins in France, initially they wanted service facilities in France, then a factory, but it was overtaken by "events".
 
Hispano-Suiza was a multi-national company with factories in both France and Spain, Marc Birkigt was actually Swiss. The company had been started in 1904 to make automobiles.
The British 20mm cannon factory was partially owned by Birkigt, at least at first.

Hispano-Suiza aircraft engines go back to about 1915, which is sort of their blessing and curse.

the WW I V-8 engine, there were a number of versions. It was very advanced for 1915-18. It was also widely licensed in WW I (including the US) and one of the Allied standard engines
Unfortunately economy (and pride?) kicked in. Birkigt had not only designed the engine, he designed some of the specialty machinery to make it. In the post WW I era and thousands (tens of thousands) of cheap/surplus engines and depression in the early 20s (not at as bad as 1929) improvements were slow. Birkigt was also prolific, designing new car engines, truck engines and gasoline engines for rail cars in addition to "new" aircraft engines. The engine that became the 12Y started in 1928 if not before and had no supercharger. The gasoline would barely tolerate any boost. Birkigt kept designing engines he could make on at least some of the existing machinery, things like bore spacing and machining the valve seats. A lot of engines used a one piece head and cylinder block and mounted two such assemblies on a crankcase. Now in such an assembley you don't have to worry about head gaskets. You do have to pull the cylinder blocks off the crankcase to do a valve job and drop the valves out the bottom of the cylinders.
Now in 1928-29-30 nobody else was making anything any better, the trouble came in when the H-S engines didn't improve that much. Hanging a supercharger off the back of the existing engine only bought a few years. Using the same head design (two valves, in line with the bore) limited breathing, the light weight construction limited power and so on.
Improved materials were only going to take you so far if you kept the same crankshaft journals crankpin sizes and kept the same basic crankcase design and so on. By 1940-41 you are flogging a very, very dead horse.
 
pbehn said:
The French did try, the first contact of Ford with Rolls Royce was for Ford to build Merlins in France, initially they wanted service facilities in France, then a factory, but it was overtaken by "events".
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Interestingly, Spain's Hispano Aviación, up until 1939 the aircraft division of Hispano-Suiza, replaced the Spanish-produced 12Z-89 engines (a development of the French Hispano-Suiza 12Y) in later versions of their own clone of Germany's Bf 109, the postwar A-1112 with British-produced Rolls Royce Merlin. Such a mixed bag of at least four nationalities in one sentence.

I expect had the Soviets had the opportunity they would have installed their VK-107 onto a Merlin-powered P-51D Mustang in order to test its performance. And if deemed worthy, it would have powered Soviet knockoffs of the Mustang, much like how the B-29 was copied as the Tupolev Tu-4 Bull. AIUI, the US sent about fifty P-51s to the USSR in 1942, but I wonder if these were Allison-powered older versions.

 
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The 12Z gained well over 200lbs (maybe 300lbs) and changed to 4 valve heads and double overhead cams. They also claim a 2800rpm limit.
Wiki, via the 1946 Wilkinson claims 1800hp for take-off, except the number don't make sense, unless RR was really bad,

Engine...........weight kg.........bore mm.......stroke mm..........Displacement L.................. Power hp t-o.............rpm................boost.
12Z.......................620....................150..................170...........................36.05..................................1800.............................2800................45.3in/7.7lbs
Griffon VI..........812......................152.................168...........................36.7......................................1820............................2750................60.5/15lbs
1947
Swiss YS-2.......685.......................150.................170............................36........................................1300............................2600..................41.4/5.7lbs
M-107A............600.......................148.............170/175.......................35........................................1600............................2800..................52.4/11.2
1948
Swiss YS-4......706........................150................170..............................36........................................1600..........................2800.....................47.2/8.6

All from Wilkinson so the M-107A maybe rather suspect. Or more than rather, newer book (Russian) 765kg for weight.
The 12Z also claims the best altitude performance. It used direct fuel injection
The YS-4 used a variable speed drive on the supercharger and direct fuel injection. (different system/company)
The YS-2 also used direct fuel injection. single speed supercharger.
The Griffon is a single stage/2 speed engine.

The specs on the 12Z are just too good to be true.

For the French in 1940-41 the 12Z needs a LOT of new machinery to make it.

every engine except the YS-2 (93 0ctane) and M-107A (95) was supposed to be using 100/130 fuel
 
No such thing as 1800 HP HS-12Z - see here.
1500 HP was it's best value. No worries - RR was good, very good; unfortunately, seems like Wikinson have had the habit to believe some manufacturers too much
 
tomo pauk said:
No such thing as 1800 HP HS-12Z - see here.
1500 HP was it's best value. No worries - RR was good, very good; unfortunately, seems like Wikinson have had the habit to believe some manufacturers too much
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Found an entry in the 1947 book for the Spanish 12Z-89, how accurate ????

The claimed for 2800rpm seems to have disappeared with time

Basically there were French Hispanos, Spanish Hispanos, Swiss Hispanos and Soviet Hispanos and none of them really managed to beat a single stage Merlin.
Durability/longevity is also subject to question. And these later ones used new crankshafts, new valve trains, new induction systems (superchargers and fuel injection)

With an older Hispano you are limited as to rpm and BMEP (cylinder pressure) and to change those you need to change the basic structure of the engine (Swiss added over 30KG to the crankshaft?) and this is what happens when you try to upgrade legacy engines. At some point just right them off and start over.
 
Other than being a touch small for the period what was wrong with the Peregrine?
 
yulzari said:
Other than being a touch small for the period what was wrong with the Peregrine?
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Engine gets blamed for the engine controls (Throttles and ???) Some (all?) Stirling's had the same system.
instead of cables and/or rods they used hydraulic lines.
Anyone familiar with old British cars/trucks/motorcycles and British gaskets/seals knows where this is going.
Having to "pump" your throttle levers to bleed the air out for better throttle response every so often while flying missions is not likely to seen favorably.
Maybe not as bad in a Sterling but in fighter you kind of want the engine to speed up when you advance the throttle when being shot at.
 
yulzari said:
Other than being a touch small for the period what was wrong with the Peregrine?
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That's about it really, at 21 liters, the Peregrine is just too small in a world of >27L Merlins et al.

But I'd like to have seen a light fighter built around a twin-supercharged 21-L Peregrine. Some akin to a Caudron C.714, but swapping out the air cooled V-12 with the Peregrine - keeping in mind that the greater hp will need to overcome the added weight of the engine and cooling system.
 
Well, since you have twice the power at altitude (12,000-15,000) you have the extra power already in hand.
Or to put it another way you have 20-23% more power than a Bf 109C.
 
Shortround6 said:
Well, since you have twice the power at altitude (12,000-15,000) you have the extra power already in hand.
Or to put it another way you have 20-23% more power than a Bf 109C.
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Talk about ~45% more power than what the Jumo 210G was making above 15000 ft (~600 HP vs. 885 HP there).
With Peregrine using 100 oct fuel for over-boost (thin blue line on the graph, starts with '??'), it's advantage is also pronounced between under 15000 ft (red line for 210G in high gear). I haven't bothered with low-altitude part of the graph.
Granted, Peregrine have had a problem of being too late to matter.

The last fully-supercharged Kestrels (availability-wise earlier than the Jumo 210G) were splitting the difference above ~14000 ft, with 745 HP at 14500 ft. <green line>

FWIW:
 
There was nothing intrinsically wrong with the Peregrine ut immediately pre war, the future was seen as being with engines like the Vulture and Sabre which were both two Peregrines on one shaft, in terms of displacement.
 

I was having trouble making sense of your chart (on my computer it comes out as below) so I converted it to a table and only then realised why you used the Griffon instead of the Merlin as the British engine.

Others who missed it will see in the table that the HS and variants are about the same capacity as the Griffon and at the end of their development the HS derivatives produce similar power to one of the earliest of Griffons.

To me it would be interesting to see the same chart with the significantly smaller Merlin and V-1710 engines added to show how far behind the 8 ball the HS and derivatives were. I also found the Griffon engine weight interesting. Presumably built with vastly improved power in mind.


 
MiTasol said:
Others who missed it will see in the table that the HS and variants are about the same capacity as the Griffon and at the end of their development the HS derivatives produce similar power to one of the earliest of Griffons.
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Unfortunately, the 1800 HP power for a service-worthy HS 12Z was probably a sales pitch, 1500 HP was the max power. Please see the post #250 here.
 
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