V-16 inline engine: pros cons?

[wuzak]

There is little doubt that the "BIG" twin heavy bomber was a bad idea for the very reason you state. However the Merlin was a 27 liter engine, the Griffon a 36 liter engine and the Vulture was a 42.5 liter engine. With it's smaller cylinders, in theory the Vulture should have been able to turn more rpm. With any given fuel the Vulture should have been able to develop much more power than the other two. All things being equal, which they obviously were not.

The Merlin had more development time in it, and had its own problems - but many of these were pre-war. They were trying to fix the Vulture in a time where they needed the resources for the Merlin and Griffon. The Griffon seems to have had a relatively trouble free development period - only 2 or 3 years before it was in production.

The Vulture should have easily been 2000hp+, and by the time the Merlin was pumping out 2000hp (1943) the Vulture probably would have been capable of much more. At the same BMEP as a Merlin with 2000hp at 3000rpm a Vulture would be giving well over 3000hp. Of course that needed, like the Merlin had before it, the reliability problems sorted before extra power could be sought.

 

[wuzak]

As for the Pennine, Rolls built the Eagle why?

The Eagle 22 was a parallel development to the Pennine, but was for a different market. The Pennine was designed for use in the post war transport industry. The Eagle was the next high performance military engine. Both were overtaken by the turbine.

That is sort of my point.

How long did it take to "fix" the Vulture AFTER it passed a type test?

About the same as it took to fix the Merlin.

There is no doubt that the Vulture was rushed through teh type test and into production before it was ready.

The P&W R-2800 had 3,500 hours before it passed a type test (on the "A" series engine) and the R-4360 had 15,000 ground hours on 23 engines. And it used R-2800 cylinders. 4 rows of seven instead of two rows of nine.

I'd say P&W were in somewhat a different situation than Allison in that they didn't have to rely on government funding to persue their development of the R-2800. They had a solid base for their business through earlier engines and a market in civil aviation. Allison did not.

Rolls-Royce, and the other British engine makers, had another situation again. They were rushing through because of an impending war.

 

[Shortround6]

The Merlin had more development time in it, and had its own problems - but many of these were pre-war. They were trying to fix the Vulture in a time where they needed the resources for the Merlin and Griffon. The Griffon seems to have had a relatively trouble free development period - only 2 or 3 years before it was in production.

The Vulture should have easily been 2000hp+, and by the time the Merlin was pumping out 2000hp (1943) the Vulture probably would have been capable of much more. At the same BMEP as a Merlin with 2000hp at 3000rpm a Vulture would be giving well over 3000hp. Of course that needed, like the Merlin had before it, the reliability problems sorted before extra power could be sought.

Once again, that is sort of the point. The Vulture wasn't supposed to be a "NEW" engine. It was supposed to be a low risk, high power engine. Use Kestrel (or Peregrine) cylinders, space them out a bit and put four on each crank throw instead of two. The pistons/piston rings should be sorted out. The valves, valve springs, valve timing, cams, cam drives, combustion chamber shape, spark plug location should already be sorted out. And apparently they were because none of the accounts I have read mention any troubles in those areas.
The Vulture is sort of an answer to those who say "why didn't they JUST use the XXX cylinder blocks in an 'X' shape to make a high powered engine? It would have been fast and easy."

 

[wuzak]

Once again, that is sort of the point. The Vulture wasn't supposed to be a "NEW" engine. It was supposed to be a low risk, high power engine. Use Kestrel (or Peregrine) cylinders, space them out a bit and put four on each crank throw instead of two. The pistons/piston rings should be sorted out. The valves, valve springs, valve timing, cams, cam drives, combustion chamber shape, spark plug location should already be sorted out. And apparently they were because none of the accounts I have read mention any troubles in those areas.
The Vulture is sort of an answer to those who say "why didn't they JUST use the XXX cylinder blocks in an 'X' shape to make a high powered engine? It would have been fast and easy."

They had some problems with the new bits, plus some with lubrication and cooling. The master rod bolting/clamping arrangement took them some time to fix - and they were considering ditching that arrangement for a pair of fork and blade rods - as had been done on the Eagle XVI. They had some issues with the location of crankcase, which caused main bearing problems, but that was solved with dowels. They were working through the engine systematically to fix its problems, as they had with the Merlin. The Peregrine also had its share of issues, even though it was basically a modernised Kestrel.

I don't think the concept of the X-24 was flawed in any way. Just that the execution wasn't as good as it had been. Given the time without the pressure of war the Vulture would have been well and truly sorted - its the way the Merlin developed.

btw, from what I understand about the Wright R-2160 Tornado, from the book by Kimble McCutcheon, is that the Tornado T-14, basically one of the Tornado's modules, completed a 50hr development test and a 150hr endurance test as specified in their development contract with the USAAC. The 150hr test was not a normal type test, as Wright engineers were able to stop the test and strip the engine to inspect it. It appears that the full engine, the T-42, never did those tests, let alone a type test.

 

[Shortround6]

The Eagle 22 was a parallel development to the Pennine, but was for a different market. The Pennine was designed for use in the post war transport industry. The Eagle was the next high performance military engine. Both were overtaken by the turbine.

I really would like to see the office memos on that one

Whoever 'OK'd' that plan should have been either fired on the spot or if that decision came as a result of months of wartime stress been sent home for a few months of bed rest.

"Lets build an air-cooled 24 cylinder "X" sleeve valve engine at the same time we are building a liquid cooled 24 cylinder "H" sleeve valve engine about 00.6% apart in displacement. It is only going to cost a few million pounds Stirling for R&D for EACH engine (if we are very lucky)* but we can limit return on investment by pitching each engine to a different market."


* One account says the Wright sank 6.5 million dollars into the Tornado program. P&W put 8 million into the R-2800 ( don't know if that is the original R-2800 or includes the "C" series) and 25 million into the R-4360. That 6.5 million would have been 62.5 million in year 2000 dollars.
Rolls-Royce continued to fund development of the Merlin for commercial applications after the war. As did Bristol with the Hercules and Centaurus. Piston engine development did not stop in 1945-46. It may have slowed considerably but there was still a market for piston engines.

Rolls-Royce, and the other British engine makers, had another situation again. They were rushing through because of an impending war.

While not quite the same sense of urgency P&W was in a bit of a hurry. Ground was being broken for a second source (shadow) factory before P&W had delivered even a dozen R-2800 engines. That is in 1940.

Wright made rather more of a hash of things. Take a Cyclone 9, shorten the stroke just a bit and put two together for a R-3350 (or, if you prefer, add two cylinders per row to an R-2600) and see how long and how much trouble they had sorting that out.

 

[Readie]

Honest answer?
A lot.
Cheers
John

 

[wuzak]

I really would like to see the office memos on that one

Whoever 'OK'd' that plan should have been either fired on the spot or if that decision came as a result of months of wartime stress been sent home for a few months of bed rest.

"Lets build an air-cooled 24 cylinder "X" sleeve valve engine at the same time we are building a liquid cooled 24 cylinder "H" sleeve valve engine about 00.6% apart in displacement. It is only going to cost a few million pounds Stirling for R&D for EACH engine (if we are very lucky)* but we can limit return on investment by pitching each engine to a different market."

The Eagle 22 wasn't a replacement for a failed Pennine program. If anything the Eagle was started earlier.

Rolls-Royce continued to fund development of the Merlin for commercial applications after the war. As did Bristol with the Hercules and Centaurus. Piston engine development did not stop in 1945-46. It may have slowed considerably but there was still a market for piston engines.

Slightly different developing an engine that has been in production for years and has a good reputation to developing a new engine which has thus far only ran on the bench.

 

[icepac]

Fiat did it.

It's record is unbroken to this day.

 

[wuzak]

Not exactly. That is a V24, but it has two separate crankshafts that are not connected in any way. The rear crank drives the front prop, and the front crank drives the rear prop. The rear half carries the induction equipment (supercharger, carb) so has to be started first, and can run by itself. The front engine can't be started until the rear one is running.

There were a lot of development problems with the AS6, many related to fuel distribution.

 

[Readie]

Not exactly. That is a V24, but it has two separate crankshafts that are not connected in any way. The rear crank drives the front prop, and the front crank drives the rear prop. The rear half carries the induction equipment (supercharger, carb) so has to be started first, and can run by itself. The front engine can't be started until the rear one is running.

There were a lot of development problems with the AS6, many related to fuel distribution.

And an annoying habit of catching fire too...

 

[Elvis]

Two quotes from wikipedia:

"In 1939, Chrysler was contracted by the US government to create a new engine for use in fighter aircraft. Chrysler responded by designing an inverted V16, the IV-2220. They tried many designs before choosing a hemispherical combustion chambered OHV head. The big V16 was rated at 2,500 hp (1,900 kW). It was finally tested in June 1945. It was installed in the P-47 Thunderbolt in place of a radial engine. This airplane was designated the XP47H. The change in engine and aerodynamics increased the top speed from 439 mph (707 km/h) to 504 mph (811 km/h). The war ended shortly after the tests, and the hemi V16 was never mass-produced, although the basic design and valvetrain setup live on in today's Hemi V8s."

"Two XP-47Hs were built. They were major reworkings of existing razorback P-47Ds to accommodate a Chrysler IV-2220-11 water-cooled 16-cylinder inverted vee engine. However, such large inline engines did not prove to be especially effective."


Anyone have some more data about this, or may verify this info?



XP-47H

Please forgive me if this has already been mentioned, but Allpar goes into some detail about this engine on their Original Hemi page.
...also goes on about how they worked out their design and later adapted to their line of cars and trucks.


Elvis

 

[wuzak]

I believe the Hemi head was common to all "hyper" engines based on the cylinder design produced by Wright Field in the ealry '30s.