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Big Piston Aero Engine using today's technology


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#101 bigleagueslider

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Posted 19 April 2013 - 02:42

Seems to suggest that the Hyper engine selection process was another example of what happens when the client interferes in the design process.


gruntguru- The decision to drop the US WWII hyper engine efforts had some legitimate basis. The overall performance of the hyper engines at the time was not significantly better than the existing big-bore air-cooled radials, and the radials were already in mass production. Pratt & Whitney came to a similar conclusion with their parallel liquid-cooled sleeve valve engine and air-cooled radial engine development efforts. After expending huge amounts of money and effort on their H-3730 liquid-cooled sleeve valve engine, they found that it was no better than their existing air-cooled radials in terms of weight, drag, power, cost, etc., so they dropped the project.

The WWII US Army and Navy needed a large number of reliable engine delivered as soon as possible. And the big bore air-cooled radials fit the bill better than anything else at the time.

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#102 gruntguru

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Posted 19 April 2013 - 03:58

Current Reno Merlins can turn at least 3,800 rpm which would not, most likely be used in a "new" aircraft engine developed, yet a lot of th talk about a new aircraft engine speaks of tuning at the level of the Reno racers.

A clean sheet design using Merlin bore and stroke and current materials technology, FEA design etc etc would definitely rev significantly harder than the Merlin's 3,000 rpm with no loss of reliability or longevity. HP would increase in line with rpm.

To make more power would require smaller cylinders (Merlin = 2.25 litre/cylinder) allowing higher rpm and higher boost. This strategy allowed the Napier Sabre for example to produce 40-50% higher specific power than the Merlin in the same era.

#103 bigleagueslider

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Posted 19 April 2013 - 06:31

A clean sheet design using Merlin bore and stroke and current materials technology, FEA design etc etc would definitely rev significantly harder than the Merlin's 3,000 rpm with no loss of reliability or longevity. HP would increase in line with rpm.

To make more power would require smaller cylinders (Merlin = 2.25 litre/cylinder) allowing higher rpm and higher boost. This strategy allowed the Napier Sabre for example to produce 40-50% higher specific power than the Merlin in the same era.



For sure, modern engine designers could make huge improvements on the Merlin's cylinder head design, piston design, crank and conrod design, supercharger design, etc. But the most significant gains would be from modern electronic fuel and ignition systems, rather than increases in engine rpm's. The most troublesome issue with Merlin engine performance was the detonation limit caused by uneven fuel mixtures at each cylinder created by the carburettor.

#104 rory57

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Posted 19 April 2013 - 06:33

And the big bore air-cooled radials fit the bill better than anything else at the time.

Remember what we are considering here are engines for weapons. If I had to go into combat trusting all to a piston engine, I would want to be fighting behind a big air-cooled radial, primarily because of their demonstrated resilience, "dependability" as Pratt and Whitney called it. Development and experience showed the original prejudice against radials in fighters to be wrong and all of the final generation of piston engine fighters used them.


#105 Bob Riebe

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Posted 19 April 2013 - 07:56

A clean sheet design using Merlin bore and stroke and current materials technology, FEA design etc etc would definitely rev significantly harder than the Merlin's 3,000 rpm with no loss of reliability or longevity. HP would increase in line with rpm.

To make more power would require smaller cylinders (Merlin = 2.25 litre/cylinder) allowing higher rpm and higher boost. This strategy allowed the Napier Sabre for example to produce 40-50% higher specific power than the Merlin in the same era.

Why?

When today's cars are using over-drives to lower rpm for efficiency, why would aircraft want to go the opposite direction?

Reliability is number one component of an aircraft engine. While there could be a slight increase in rpm due to simple knowledge gained over the decades, high rpm meaner higher stress and unless one is in a war-bird that absolutely needs that ability to go to the red-line at times, for a civilian bird, no need.

Smaller is not better in an aircraft engine.
The greatest power with the least effort is.
Remember stated power level must be able to be maintained for 2000 hours.
Do that to these mega hp automobile engines and you have scrap metal.

#106 Wuzak

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Posted 19 April 2013 - 11:13

Why?

When today's cars are using over-drives to lower rpm for efficiency, why would aircraft want to go the opposite direction?

Reliability is number one component of an aircraft engine. While there could be a slight increase in rpm due to simple knowledge gained over the decades, high rpm meaner higher stress and unless one is in a war-bird that absolutely needs that ability to go to the red-line at times, for a civilian bird, no need.

Smaller is not better in an aircraft engine.
The greatest power with the least effort is.
Remember stated power level must be able to be maintained for 2000 hours.
Do that to these mega hp automobile engines and you have scrap metal.



I think your missing the premise of the thread - that the jet engine was never invented and military aircraft were using piston engines.

So we are talking about ultimate performance engines for fighter aircraft.

Bigger isn't always better - packaging is very important for fighter aircraft.

What engine needs to keep rated engine power for 2000 hours?

Edited by Wuzak, 19 April 2013 - 11:14.


#107 Wuzak

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Posted 19 April 2013 - 11:20

Remember what we are considering here are engines for weapons. If I had to go into combat trusting all to a piston engine, I would want to be fighting behind a big air-cooled radial, primarily because of their demonstrated resilience, "dependability" as Pratt and Whitney called it. Development and experience showed the original prejudice against radials in fighters to be wrong and all of the final generation of piston engine fighters used them.


Like the Supermarine Spitfire 24 and Seafire 46/47?
Supermarine Spiteful & Seafang?
CAC CA-15.
Westland Wyvern
North American P/F-82.


#108 Bob Riebe

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Posted 19 April 2013 - 18:01

I think your missing the premise of the thread - that the jet engine was never invented and military aircraft were using piston engines.

So we are talking about ultimate performance engines for fighter aircraft.

Bigger isn't always better - packaging is very important for fighter aircraft. (Yes which is why the ultra agile F4D was a replaced with a considerably larger F5D that all who flew it said was a much, much better aircraft. The smaller F4D, while the most agile aircraft used up to the F-22, simply was too small to suffer the stresses and perform the mission it was supposed to do. The P-47 and F-105 are fine examples of aircraft that were large enough to perform the job, shoot down enemy aircraft and still get the pilot home with heavy damage)

What engine needs to keep rated engine power for 2000 hours?

"Aircraft engines are built to very different criteria to those in automobiles. As you cannot pull over to the side of the sky in the event of breakdown, reliability has been the first and foremost priority. These designs have been around for decades, and just about every possible bug has been designed out. They are also designed to give maximum power output continuously for 2000 hours. If you tried that with an automobile engine, it would be in the scrap yard very fast indeed! As a student pilot, you will be expected to understand the basic principles of operation, and you will be taught how to check oil levels and check for integrity of the alternator belt."==From an introduction for student pilots.

The FAA has requirements to be met, as did the military during WWII.

Durability is as important for a war-bird as it is for a civilian aircraft, just different reasons.

Of the aircraft you listed in your other post, all but two were based on already existing designs while the Aussies had no independent engine industry so they used what the Brits had available at the moment to suit their needs.
As I said earlier, it is a well known fact the USAF really wanted the P-47 with its much tougher radial in Korea.
Any water cooled engine would not have survived in "Nam the way the Skyraider did.

Edited by Bob Riebe, 19 April 2013 - 20:48.


#109 saudoso

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Posted 19 April 2013 - 19:49

But you have the fully rated max power a pilot can use to take off and cruise in a hurry and then that bit more the guy can pull from the engine while flying through dodge city, right?

#110 gruntguru

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Posted 19 April 2013 - 23:36

Why?

When today's cars are using over-drives to lower rpm for efficiency, why would aircraft want to go the opposite direction?

To make more power - read the original post and the question posed there.

Reliability is number one component of an aircraft engine. While there could be a slight increase in rpm due to simple knowledge gained over the decades, high rpm meaner higher stress and unless one is in a war-bird that absolutely needs that ability to go to the red-line at times, for a civilian bird, no need.

You have responded to my post without even reading it properly.

"A clean sheet design using Merlin bore and stroke and current materials technology, FEA design etc etc would definitely rev significantly harder than the Merlin's 3,000 rpm with no loss of reliability or longevity. HP would increase in line with rpm.

To make more power would require smaller cylinders (Merlin = 2.25 litre/cylinder) allowing higher rpm and higher boost. This strategy allowed the Napier Sabre for example to produce 40-50% higher specific power than the Merlin in the same era.

You ask Why? Go ask Napier. Why did they bother?

#111 Wuzak

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Posted 20 April 2013 - 00:04

Yes which is why the ultra agile F4D was a replaced with a considerably larger F5D that all who flew it said was a much, much better aircraft. The smaller F4D, while the most agile aircraft used up to the F-22, simply was too small to suffer the stresses and perform the mission it was supposed to do. The P-47 and F-105 are fine examples of aircraft that were large enough to perform the job, shoot down enemy aircraft and still get the pilot home with heavy damage


The F5D was a development of the F4D, taking advantage of improved understanding of aerodynamics and improved jet engines. But it had the same wing span and wing area. The only major dimension change was the lengthening of the fuselage. Only 4 prototype F5Ds were built.


"Aircraft engines are built to very different criteria to those in automobiles. As you cannot pull over to the side of the sky in the event of breakdown, reliability has been the first and foremost priority. These designs have been around for decades, and just about every possible bug has been designed out. They are also designed to give maximum power output continuously for 2000 hours. If you tried that with an automobile engine, it would be in the scrap yard very fast indeed! As a student pilot, you will be expected to understand the basic principles of operation, and you will be taught how to check oil levels and check for integrity of the alternator belt."==From an introduction for student pilots.


Is that a civilian requirement for general aircraft?


The FAA has requirements to be met, as did the military during WWII.


The US military had a 150 hour type test.

Not even the R-2800 had time between overhaul of 2000 hours, let alone the ability to run at rated power for 2000 hours.


Of the aircraft you listed in your other post, all but two were based on already existing designs while the Aussies had no independent engine industry so they used what the Brits had available at the moment to suit their needs.


Can add the de Havilland Hornet to the list.

The P-82 may look like two P-51s, but it wasn't. It was very much a new aeroplane.

The P-51H was a thoroughly redesigned aircaft.

The piston engine replacement for the late model Spitfire was going to be a liquid cooled powered fighter - either a Supermarine design, or a Hawker development.

Posted Image

No air cooled fighter was considered to replace the Spitfire (or Mustang, for that matter).


As I said earlier, it is a well known fact the USAF really wanted the P-47 with its much tougher radial in Korea.
Any water cooled engine would not have survived in "Nam the way the Skyraider did.


Air National Guard units still had P-47s, so if the USAF really wanted them they could have got them. But the USAF didn't really want to do ground support anyway.

The Typhoon was a tough old bird that did as well as any air-cooled fighter in the CAS role. I'm sure if they weren't all scrapped some would have been useful in Vietnam. It's all in the way the radiator is arranged and armoured.

With Napier's annular radiator armouring would have been even simpler.

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#112 Bob Riebe

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Posted 20 April 2013 - 04:20

To make more power - read the original post and the question posed there.


You have responded to my post without even reading it properly.

"A clean sheet design using Merlin bore and stroke and current materials technology, FEA design etc etc would definitely rev significantly harder than the Merlin's 3,000 rpm with no loss of reliability or longevity. HP would increase in line with rpm.

To make more power would require smaller cylinders (Merlin = 2.25 litre/cylinder) allowing higher rpm and higher boost. This strategy allowed the Napier Sabre for example to produce 40-50% higher specific power than the Merlin in the same era.

You ask Why? Go ask Napier. Why did they bother?

I read the original post and all the supposed great leaps and bounds are simple hot rod think which does not apply to aircraft engines, PERIOD.
There would be gains obviously but not even remotely close to the pit-in-the-sky gains some here think would happen.

A clean sheet engine would would be an improvement with survivability the number one concern regardless of power output.
The German Griffon showed what happens when pie-in-the-sky tactics are applied to a warplane.


The Sabre like the Centaurus were sleeve valve.
The main reason they are not up rated for Reno is lack of return for investment to allow them to go head to head with the poppet valve engines.
The Sabre had 24 cylinders, if they were not smaller than those of a Merlin it would have been a huge engine.
It was 82 by 40 2360 lbs, and Merlin is 88 by 30 1640 lbs, and Griffon is 81 by 30 1980 lbs.
Fuel consumption for Sabre max cruise 117 gph, Merlin 88 gph.
For the weight and hp of a Sabre one could use a R 3350 which weighs 2670 has higher hp with less complexity, and greater chance to survive battle damage, so the Sabre has no real advantages.



#113 Bob Riebe

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Posted 20 April 2013 - 06:27

The F5D was a development of the F4D, taking advantage of improved understanding of aerodynamics and improved jet engines. But it had the same wing span and wing area. The only major dimension change was the lengthening of the fuselage. Only 4 prototype F5Ds were built. ------------ (It had the SAME jet engine and was over 200 mph faster. It lost out to the Crusader for production while the prototypes were used by NASA until the seventies.
Get the book on the F4D. The designer of the aircraft said its thin wing construction was the worst mistake he made in his career. All the mistakes of the F4D were fixed and while the Skylancer had a slightly higher wing loading all the pilots who flew it, loved it.
F4D had a wing loading of 41 lbs/ft, the F5D 43 lbs/ft, the F-22 has 77 lbs/ft, the F-16 has 88 lbs/ft, the F-15 has 73 lbs/ft, the F-106 had 52 lbs/ft, F-8 had 77 lbs/ft and the Mig 21 has 77 lbs/ft.
Wing loading determines how tight and quickly an aircraft can turn, lower is better. The other deciding factor is ratio of thrust to weight. Delta wings bleed off air speed quicker than other wing forms which is why the USAF official edict for many of its aircraft was SPEED IS LIFE.
I spoke to some F-106 pilots who said if they had, had today's 30,000 lb wet thrust engine they could have eaten F-15s for dinner. One Navy pilot flew the Six on pilot exchange in a Red Flag type exercise and technically shot down all comers including members of the F-14 squadron he was a member of. He said it was a good airplane, you just have to fly it the way it flies best.

The lack of engine power, especially at certain altitudes was/is the death knell for some fighters and fighter bombers, particularly the Mig-21.
The F-105 had a wing loading of 93 lbs/ft but had the engine power to simply leave opposing aircraft in the dust and come around again it it so chose, which is why it could dominate the Mig 17 which had a wing loading of 48 lbs/ft.
Pilots said if they had, had the F4D in 'Nam, the Navy kill ration would have a lot higher. It could have turned inside and out climbed at low altitude anything in the N. Viets Air Force.
It was a dedicated interceptor which made it unsuitable for the multi-tasks needed in Vietnam especially its very short range.)


Is that a civilian requirement for general aircraft? --------------- (It is a TBO, time between overhaul requirement, and as with all government rules, there are different rules for different type aircraft depending on weight, number of engines etc. The test is still 150 hours but the FAA feels the test, which is run in stages equals 1000 hours.)

The US military had a 150 hour type test.
Not even the R-2800 had time between overhaul of 2000 hours, let alone the ability to run at rated power for 2000 hours.

Air National Guard units still had P-47s, so if the USAF really wanted them they could have got them. But the USAF didn't really want to do ground support anyway.
The Typhoon was a tough old bird that did as well as any air-cooled fighter in the CAS role.
With Napier's annular radiator armouring would have been even simpler.

It still had a radiator which was the Achilles heel of the Mustang in Korea.
I am sure if the Bearcats in Vietnam had not been worn out they would have still been used.
There was barely enough spare parts to keep the National Guard P-47s flying which is why their Guard duty was small and short.
Look it up on the net, the Air Force General wanted the P-47 in Korea but there were not enough aircraft and even fewer spare parts. It has been documented many times in books.
It was the radial engined Skyraiders and Corsairs that soldiered on, the Corsair remaining in production till 1953.


From:

The Air War Nobody Told You About
P-47 Thunderbolts on the Continent of Europe, 1944-45
Combat Aircraft, March 2004
by Robert F. Dorr and Thomas D. Jones

Low-Level Hell
To a man, the dozen P-47 pilots interviewed for this article agree that they might not be alive today had they been flying the P-51 instead of the rugged, eminently survivable Thunderbolt. As Americans learned later in Korea, the under-fuselage cooling system of the P-51 made the Mustang vulnerable to gunfire at low altitude, even small-arms fire from infantry rifles. The Mustang was a feisty filly at higher elevation, but the Thunderbolt offered the best chance to stay alive down low where the metal was flying around.

Not for nothing, the Farmingdale, N. Y. manufacturer of the Thunderbolt was called the "Republic Iron Works" and had a reputation for building fighters that were big, roomy, and survivable. One P-47 returned to its European base with body parts from a German soldier embedded in its engine cowling. Another landed safely riddled with 138 holes from bullets and shrapnel.


Edited by Bob Riebe, 20 April 2013 - 18:11.


#114 Wuzak

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Posted 20 April 2013 - 07:55

The German Griffon showed what happens when pie-in-the-sky tactics are applied to a warplane.


German Griffon - the Heinkel He 177 Grief?

What was pie in the sky about that? Other than the requirment to be able to dive bomb.

Poor execution does not make it pie in the sky.



I read the original post and all the supposed great leaps and bounds are simple hot rod think which does not apply to aircraft engines, PERIOD.
There would be gains obviously but not even remotely close to the pit-in-the-sky gains some here think would happen.


A lot of the suggestions here are extensions of the proposal Tresilian put forward in 1945 - a 10.3l X-16 that makes as much power as the Griffon using revs and big boost. Most of the suggestions centre around direct fuel injection, other forms of efi and improvemnets to materials, engine design and production techniques.


A clean sheet engine would would be an improvement with survivability the number one concern regardless of power output.


Performance is, perhaps, the biggest part of surviveability.



The Sabre like the Centaurus were sleeve valve.
The main reason they are not up rated for Reno is lack of return for investment to allow them to go head to head with the poppet valve engines.


Or, simply, a lack of engines. There are no flyable Sabres in the world, as far as I am aware. There are only a handful of Centauruses (Centauri?).


The Sabre had 24 cylinders, if they were not smaller than those of a Merlin it would have been a huge engine.
It was 82 by 40 2360 lbs, and Merlin is 88 by 30 1640 lbs, and Griffon is 81 by 30 1980 lbs


You need the full dimensions. The Sabre was 46" high x 40" wide x 82" long (some later Sabres were taller still, around 47-48"). Depending on version Sabres could be as much as 2550lb.
The Griffon (2 stage) engine was 46" high x 30" wide x 81" long. 1980lb.
The Merlin (2 stage) 40" high x 30" wide x 88" long. 1650lbs, depending on accesories.

The Wright R-3350 was 56" in diameter, and 77" long.

During WW2 the R-3350's maximum rating was 2200hp.

The Sabre IIB was rated at 2400hp and maximum continuous of 2065hp @ 4750ft. The Sabre V was evolved by 1944 and had a combat rating of 2600hp, and a maximum continuous of 2165hp. In 1944 the Sabre was probably more reliable than the R-3350. The Sabre VII was combat rated for over 3000hp just post war, and 2235hp max continuous. With ADI, takeoff power was 3500hp.

Eventually the R-3350 was brought up to around 2800hp maximum, and up to 3700hp in turbo-compound form (but also much heavier).

To put that in perspective, in 1944 the R-4360 was rated at 3000hp for around 3800lbs. Post war it was uprated to 3500hp. The most it got (without the "pie in the sky" VDT versions) was around 3700-3800hp.

Meanwhile Sabres had tested, comfortably, to over 4000hp.


Fuel consumption for Sabre max cruise 117 gph, Merlin 88 gph.


What is the specific fuel consumption. At max power a Merlin would be around 0.60-0.65lb/hp/hr, or worse.

And what actual power output at that gph reading? 2600hp for the Sabre vs 2000hp for the Merlin?


For the weight and hp of a Sabre one could use a R 3350 which weighs 2670 has higher hp with less complexity, and greater chance to survive battle damage, so the Sabre has no real advantages.


A) The R-3350 didn't have more power than the contemporary Sabre.
B) The installed weight of the Sabre would undoubtedly be more. The power to installed weight would be similar.
C) The Hawker Tempest used both the Sabre and the Centaurus, the latter being similar in capacity and size to the R-3350. The Tempest II (Centaurus) outperformed the Tempest V (Sabre IIB, V, VI or VII). The engine power was similar. The problem was that the chin radiator was not very good for drag. The Tempest I (Sabre IV, leading edge radiators) had less power than the Tempest II, but was significantly faster. Similarly, the Hawer Fury prototype fitted with Sabre and annular radiator was faster than when fitted with the Centaurus.
D) A Sabre fitted in an aircarft designed around the Centaurus had space to spare.
E) The advantage the Sabre had over the R-3350 was mainly power. In late WW2 the Sabre was capable of continuous power nearly equal to or exceeding the maximum power of the R-3350.

As an aside, the Vulture had tested on the bench at 2500hp before its cancellation. So, before 1941. It weighed 2450lb, but had production continued the reduction gear would have been redesigend for considerable weight savings (c. 200lb).






#115 rory57

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Posted 20 April 2013 - 09:02

Like many with an interest in piston engine history and in WW2 era aircraft, a favourite "what if" is the Rolls-Royce Crecy.

Surely modern fuel injection, closed loop engine management, modern materials, lubricants and perhaps above all the modern understanding of and tools for modelling combustion chamber behaviour would make a success of the sleeve-valve two stroke?

I know it would be fantastically noisy (even by military aircraft standards) but the potential in a fighter is enhanced by the contribution of exhaust thrust: 1942 estimates for top speed of a Spitfire were that exhaust thrust would yield an extra 48mph at 20,000 feet compared to the 19mph exhaust contribution with a Griffon engine installation. Exhaust flames would make this a no-no at night, so the turbo-blown variant would have to be developed as well.

I think that it is the relative mechanical simplicity that appeals as much as the performance gains of using the major moving parts twice as often. Now, if RR are working on the Crecy, what could Bristol achieve with a two stroke air cooled radial using the same Crecy principles? Dream on..........

#116 Wuzak

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Posted 20 April 2013 - 09:24

Like many with an interest in piston engine history and in WW2 era aircraft, a favourite "what if" is the Rolls-Royce Crecy.

Surely modern fuel injection, closed loop engine management, modern materials, lubricants and perhaps above all the modern understanding of and tools for modelling combustion chamber behaviour would make a success of the sleeve-valve two stroke?

I know it would be fantastically noisy (even by military aircraft standards) but the potential in a fighter is enhanced by the contribution of exhaust thrust: 1942 estimates for top speed of a Spitfire were that exhaust thrust would yield an extra 48mph at 20,000 feet compared to the 19mph exhaust contribution with a Griffon engine installation. Exhaust flames would make this a no-no at night, so the turbo-blown variant would have to be developed as well.

I think that it is the relative mechanical simplicity that appeals as much as the performance gains of using the major moving parts twice as often. Now, if RR are working on the Crecy, what could Bristol achieve with a two stroke air cooled radial using the same Crecy principles? Dream on..........


I would think that cooling a 2 stroke like teh Crecy would be problematic for an air-cooled engine.

btw There was a turbo-compound version of the Crecy developed and tested.

#117 Wuzak

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Posted 20 April 2013 - 09:49

The Sabre had 24 cylinders, if they were not smaller than those of a Merlin it would have been a huge engine.


If the Sabre had 24 Merlin sized cylinders it would have been a 3300 cubic inch engine.

The V-3420 was basically two V-1710s on a common crankcase, with a single accesories section. It was 56" wide, 39" high and 98" long, 2600lbs, 2600hp easily.


#118 rory57

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Posted 20 April 2013 - 15:27

Blind alley dept.: the Wright Tornado. You can see why they cancelled........

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#119 bigleagueslider

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Posted 23 April 2013 - 03:37

Blind alley dept.: the Wright Tornado. You can see why they cancelled........


rory57- At one time Wright produced some fairly decent engines. But by mid-WWII, Wright's engineering dept. did not have anywhere near the level of competence it once had. The most obvious example of this was the serious ongoing problems they had developing the R-3350. The R-3350 engine problems were the biggest cause of delay with the B-29 program, and R-3350 engine failures caused lots of B-29 crashes and crew casualties.

As for the Wright Tornado, just imagine what a good engine designer using modern engineering tools and technology could do given the tens-of-millions spent on the Tornado project.


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#120 Wuzak

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Posted 23 April 2013 - 05:18

As for the Wright Tornado, just imagine what a good engine designer using modern engineering tools and technology could do given the tens-of-millions spent on the Tornado project.


I guess they would not end up with a 6 row, 7 bank radial with three crankshafts and 7 power lay-shafts. But it would be just as compact, give more power with better fuel efficiency and weigh less.


#121 PJGD

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Posted 24 April 2013 - 00:47

Am not convinced with the argument that air cooled engines would be the best solution for a modern fighter engine on the basis of ability to take hits and keep on flying. If we are going to accept EFI and electronic engine management as indeed we must, then we must also accept laser-guided and heat-seeking missiles which generally have a good first time knock-out performance. Thus the advantage goes to speed and performance which unquestionably gives the liquid-cooled engine prime position.

Here is another benchmark: During the war, BMW were developing a new engine, the air-cooled Type 802 and thus this could be considered an example of the state of play late in the big engine period. It was a two-row 18 cylinder 58 litre Ø156 X 174 mm 2-stage blown engine weighing 1530 kg (3380 lb), good for ~3000 HP. This performance works out to ~17 bar BMEP at rated. Modern boosted automobile engines exceed this performance handily, with 30 bar [at peak torque] being within sight.

PJGD


#122 Bob Riebe

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Posted 24 April 2013 - 05:27

Am not convinced with the argument that air cooled engines would be the best solution for a modern fighter engine on the basis of ability to take hits and keep on flying. If we are going to accept EFI and electronic engine management as indeed we must, then we must also accept laser-guided and heat-seeking missiles which generally have a good first time knock-out performance. Thus the advantage goes to speed and performance which unquestionably gives the liquid-cooled engine prime position.

Here is another benchmark: During the war, BMW were developing a new engine, the air-cooled Type 802 and thus this could be considered an example of the state of play late in the big engine period. It was a two-row 18 cylinder 58 litre Ø156 X 174 mm 2-stage blown engine weighing 1530 kg (3380 lb), good for ~3000 HP. This performance works out to ~17 bar BMEP at rated. Modern boosted automobile engines exceed this performance handily, with 30 bar [at peak torque] being within sight.

PJGD

It was abandoned because it was an over weight overly complex failure.




#123 Bob Riebe

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Posted 24 April 2013 - 05:31

German Griffon - the Heinkel He 177 Grief?

What was pie in the sky about that? Other than the requirment to be able to dive bomb.

Poor execution does not make it pie in the sky.

The engines were the aircrafts reason for being a miserable failure, period.

Many authors that comment on the aircraft, say if it had simply used four conventional engines it would probably have been successful.



#124 Wuzak

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Posted 24 April 2013 - 05:50

Am not convinced with the argument that air cooled engines would be the best solution for a modern fighter engine on the basis of ability to take hits and keep on flying. If we are going to accept EFI and electronic engine management as indeed we must, then we must also accept laser-guided and heat-seeking missiles which generally have a good first time knock-out performance. Thus the advantage goes to speed and performance which unquestionably gives the liquid-cooled engine prime position.

Here is another benchmark: During the war, BMW were developing a new engine, the air-cooled Type 802 and thus this could be considered an example of the state of play late in the big engine period. It was a two-row 18 cylinder 58 litre Ø156 X 174 mm 2-stage blown engine weighing 1530 kg (3380 lb), good for ~3000 HP. This performance works out to ~17 bar BMEP at rated. Modern boosted automobile engines exceed this performance handily, with 30 bar [at peak torque] being within sight.

PJGD


The experimental Merlin RM.17SM ran at 2620hp @ 3150rpm, +36psi boost + ADI. That equates to a BMEP of 27.8bar.

So, if you can get BMEP of 30 bar and higher revs you could probably push a Merlin beyond 3000hp.

#125 Wuzak

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Posted 24 April 2013 - 05:54

The engines were the aircrafts reason for being a miserable failure, period.

Many authors that comment on the aircraft, say if it had simply used four conventional engines it would probably have been successful.


The engines were installed poorly - which led to many of the problems. One of the problems was a lack of a firewall....

The DB 606 and DB 610 coupled engines worked fine in other aircraft, albeit in fewer numbers.

I believe there were a few problems with the airframe itself.

Still, it was the basis for this:

Posted Image

Posted Image

Edited by Wuzak, 24 April 2013 - 05:55.


#126 MatsNorway

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Posted 24 April 2013 - 06:24

You guys told me and Tony that fuel consumption was not important vs horsepower. Surely this means a methanol engine and surely that means less focus on cooling.



#127 GreenMachine

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Posted 24 April 2013 - 06:39

The engines were the aircrafts reason for being a miserable failure, period.

Many authors that comment on the aircraft, say if it had simply used four conventional engines it would probably have been successful.


Bob, I think (as Wuzak has said) there were structural issues with the aircraft. If the engine installation had been implemented better, it would have been more successful, but now we are playing 'if onlys' :wave:

#128 rory57

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Posted 24 April 2013 - 10:15

You guys told me and Tony that fuel consumption was not important vs horsepower. Surely this means a methanol engine and surely that means less focus on cooling.


Good point. I wonder if it was ever considered?

In the context of war conditions, a special fuel fior fighters would have been a pain for the supply chain but then again there were several grades of fuel available to allied combat aircraft.in WW2.

Would there have been enough Castrol R to go around? What a great smell that is, almost as good as nitro!


#129 Tony Matthews

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Posted 24 April 2013 - 10:33

...Castrol R to go around? What a great smell that is...

When I was a teenager I used to run my Mother's lawnmower on Castrol R 30. You don't smell it often nowadays, but I have been known to drive some distance out of my way to follow the trail of a motorbike using it. Still got a can somewhere...

#130 Wuzak

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Posted 24 April 2013 - 11:23

You guys told me and Tony that fuel consumption was not important vs horsepower. Surely this means a methanol engine and surely that means less focus on cooling.



Good point. I wonder if it was ever considered?

In the context of war conditions, a special fuel fior fighters would have been a pain for the supply chain but then again there were several grades of fuel available to allied combat aircraft.in WW2.

Would there have been enough Castrol R to go around? What a great smell that is, almost as good as nitro!



Interestingly the Rolls-Royce R used a methanol fuel blend for the 1931 Schneider Trophy race. The final spec was 30% benzole, 60% methanol, and 10% acetone and 4.2cc TEL per gallon. The R used 8:1 CR (Merlin and Griffon 6:1) and +18psi boost at sea level. It had the same bore and stroke as the latter Griffon, and yet was capable of running at 3200rpm+, compared to the Griffon's 2750rpm.

I guess that's the difference between a race engine and a production engine. Reportedly Rs had to be replaced after about an hour's running.

Fuel efficiency would be less important for an interceptor type - so long as it still had enough endurance to catch the enemy and shoot them down.

Obviously fuel efficiency was a major consideration for long range escorts, such as the Mustang.

#131 Kelpiecross

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Posted 24 April 2013 - 13:57

Even though this is a very interesting topic I think its basic premise is a bit unlikely. I don't see how you could have a "parallel universe" where mechanical and computer etc. technology continued as it has in "our universe" up to the present day without the jet engine appearing. Certainly you couldn't have turbocharger and turbocompound etc. engines without the jet engine happening.

Also most of these extreme and frankly outlandish (but interesting) aero engines would not have continued to be developed except in the extreme conditions of war - and that would have made the jet engine even more likely (as it did in this universe).

This situation reminds me of the "steam punk" genre where internal combustion engines were never invented and steam engines continued to be developed - an interesting idea but the IC engine was always going to happen.

#132 JtP1

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Posted 24 April 2013 - 15:14

The engines were installed poorly - which led to many of the problems. One of the problems was a lack of a firewall....


One of the 57 causes of 177 engine fires.

#133 rory57

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Posted 24 April 2013 - 17:17

When I was a teenager I used to run my Mother's lawnmower on Castrol R 30.


I found that a bit of Girling Red brake fluid in the Suffolk Punch tank would Yield the great smell of 'R. (Whilst researching the performance enhancing properties of, well, anything liquid I could get my hands on.)

#134 Bob Riebe

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Posted 24 April 2013 - 19:35

Also most of these extreme and frankly outlandish (but interesting) aero engines would not have continued to be developed except in the extreme conditions of war - and that would have made the jet engine even more likely (as it did in this universe).

The fact that engine exhaust thrust was being heavily studied to be incorporated into powering the aircraft by the wars end shows how true what you said is.

The fact that magnetos are still used in aircraft shows how different engine dynamics between automobile and aero-planes are which is why I dismiss the "all you have to do" attitude as much as I do.

#135 bigleagueslider

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Posted 25 April 2013 - 00:34

Even though this is a very interesting topic I think its basic premise is a bit unlikely. .....


Klepiecross- The notion of a big recip aero engine using modern technology becoming a reality may not be as far-fetched as you might think. Consider how turboprop commercial aircraft have recently made a comeback for many routes as jet fuel prices have remained high. I could imagine someone with deep pockets creating a modern recip turbodiesel aero engine in the 1500-2000 hp class that could be used for commuter aircraft. The recip engine would be 1/2 the cost of an equivalent turboprop, and it would use far less fuel.

#136 Bob Riebe

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Posted 29 April 2013 - 04:34

Kermit Weeks has at least two Napier Sabre engines and is putting on in the Tempest MkV he is have rebuilt.

#137 Magoo

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Posted 30 April 2013 - 12:54

Here's a fellow you've probably heard of in regard to his motorcycle exploits. However, be it known that EJ Potter was also a big fan of the Allison V-1710 -- even named his daughter Alison -- and explored various novel applications for their use. (For example, he used one to power the generator for the world's fastest slot car.) Below, here's an installation on his wife's grocery vehicle.

Yes, EJ was an interesting individual. Lost him one year ago today to Alzheimer's. Brief story and some photos:


Remembering EJ Potter | Mac's Motor City Garage.com



Posted Image


#138 Magoo

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Posted 01 May 2013 - 22:52

....more teasers on EJ, a true American original.



Remembering EJ Potter | Mac's Motor City Garage.com


Here's his Allison V-1710 powered generator for the world's fastest slot car. The big reels are for the metal conductor strips that were laid down the track.



Posted Image


Here's the invention that made him totally famous as the Michigan Madman, the Chevy-powered exhibition bike. He built the first one when he was 19. Direct drive, no clutch. If you saw it run you never forgot it.

Posted Image







#139 gruntguru

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Posted 01 May 2013 - 23:25

Here's the invention that made him totally famous as the Michigan Madman, the Chevy-powered exhibition bike. He built the first one when he was 19. Direct drive, no clutch. If you saw it run you never forgot it.




Advertisement

#140 desmo

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Posted 01 May 2013 - 23:47

OK, how did it go from a standing start direct drive? Was the rear wheel held up off the ground?

#141 Magoo

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Posted 02 May 2013 - 00:40

OK, how did it go from a standing start direct drive? Was the rear wheel held up off the ground?


Yep, axle stand just visible through the tire smoke.

#142 gruntguru

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Posted 02 May 2013 - 04:49

How about a view of the custom saddle - specially sculpted to fit the massive cajones?

#143 MatsNorway

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Posted 02 May 2013 - 16:11

Thats the maddest thing ever. 10.4

Edited by MatsNorway, 02 May 2013 - 16:19.


#144 Magoo

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Posted 02 May 2013 - 23:16

EJ said getting the bike off the line and down the track came down to body english and more throttle, more throttle. Rules #1, 2, and 3 were Never Ever Ever back out of the throttle no matter what, which would only induce a vicious tank slapper followed by a violent highsider. When he told me this he did a pantomime of a guy on a diving board.

Funny how time marches on. Now there are lots of street bikes quicker than this, but it's an entirely different thing. EJ would search the junkyards for certain brands of used tires that would hold up under the abuse and work the way he wanted.

#145 gruntguru

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Posted 02 May 2013 - 23:45

10 seconds is pretty good considering:
- poor weight distribution/transfer. The bike doesn't look even close to lifting the front wheel.
- smoking launch on a cold tyre
- no "hook up" till at least 1/2 or 3/4 track

His bikes were clearly never optimised to run great times. They were designed to put on a spectacular show and succeeded magnificently.

#146 MatsNorway

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Posted 03 May 2013 - 13:25

A clutch and some good tires and the thing would smoke most R bikes.

#147 Bob Riebe

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Posted 03 May 2013 - 19:17

I wonder, was he the catalyst for the V-8 street bikes that showed up in the late eighties and nineties?

#148 Magoo

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Posted 03 May 2013 - 22:47

I wonder, was he the catalyst for the V-8 street bikes that showed up in the late eighties and nineties?


I don't think so.... the Boss Hoss is a completely different deal -- longitudinal engine and 90 degree drive. Maybe EJ's bike planted the suggestion.


#149 desmo

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Posted 04 May 2013 - 00:26

I won't do a clutch or brake job without my immaculate white lab coat. One must have standards.

#150 Magoo

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Posted 04 May 2013 - 20:56


You perfectly anticipated the follow-up story just now posted:


http://www.macsmotor...tter-in-action/

By the way, this video was done July 4, 1999, when he came out of decades of retirement to ride the bike one more time. This is reportedly the last time he rode one of his Widowmakers. At least two of the bikes still exist today.