Build the perfect water cooled engine

[Readie]

It may be a litle vulgar but I would say that in the end the Luftwaffe lost.

Nothing vulgar in stating the truth MN.
Cheers
John

 

[fastmongrel]

I have often wondered what would have happened if Napiers had built on the succes of the Napier W 12 Lion instead of going down the route of the immensely complicated Napier H engines. A 36 litre overhead camshaft 4 valve head W12 Napier with development starting in the early 30s sounds like fun and might have been a good fallback if Rolls Royce hadnt got there Merlin bugs sorted out. Could have been called the Napier Tiger and might have been the ideal Fleet Air Arm engine.

 

[fastmongrel]

Nothing vulgar in stating the truth MN.
Cheers
John

You cant handle the truth (copyright Jack Nicholson)

 

[Shortround6]

proof? haha just kidding.. would take 4ever. bottom line in the heat of battle, I'm sure some
numbers got fudged. but please post the top ten allied, I want to compare it to Luftwaffe loss
lists. thanks.

Why bother, you made an outrageous statement about the top ten German Aces which , to take nothing away from them, wasn't even close to being true. You tried to extend it to the top 20 and that doesn't have a snowballs chance in Hades of being true and now you want to change the conditions again?

 

[Readie]

Ah... the most precious of commodities 'the truth'
Wars have started over a lot less ( paraphrase Tony Blair)

 

[Readie]

.......

 

[Shortround6]

The problem with a boxer engine is that it lacks rigidity and can be wide.

The motor cannon is also dependent on the disposition of the supercharger and attendant ancillaries. The reason why the Merlin could not carry a motor cannon was that the supercharger was large and in the way, while the intake piping was also in the way. In two stage engines there was also the aftercooler. It was a similar case for the Allison.

A flat engine may have less of a problem with intake runners and/or exhausts, but the supercharger may still be in the way.

The Merlin's reduction gearbox was therefore able to be designe so as to give the minimum frontal cross section from the engine.

There was at least one flat 12 that had the supercharger horizontal underneath the engine but that sort of kills the low height idea. So does the raised prop-shaft for the cannon. With the big gear going around the prop-shaft it is going to stick up a number of inches over the cannon barrel.

 

[Shortround6]

I have often wondered what would have happened if Napiers had built on the succes of the Napier W 12 Lion instead of going down the route of the immensely complicated Napier H engines. A 36 litre overhead camshaft 4 valve head W12 Napier with development starting in the early 30s sounds like fun and might have been a good fallback if Rolls Royce hadnt got there Merlin bugs sorted out. Could have been called the Napier Tiger and might have been the ideal Fleet Air Arm engine.

The problem with the 'W' engine is that it has a lot of frontal area. The Lion was about a foot wider than a Merlin and every bit as tall. Makes for a rather poor view over the nose. as for the 36 litres, are you talking about bigger cylinders or adding them for a W-18? With the 12 you can have a short, sturdy crankcase and crankshaft. Going to the 18 gives you a crankcase and crankshaft as long as the V-12 except you have the weight and complication of another cylinder bank.

 

[Lighthunmust]

I am beginning to think I could have saved the $120 I just spent on three aero engine books and got just as good a learning experience reading the posts some of you are are making. Bravo gentlemen!

 

[tomo pauk]

The problem with a boxer engine is that it lacks rigidity and can be wide.

I've addressed the width issue already.
Is the alleged lack of rigidity true problem for aircraft usage (high Gs so on) - perhaps you can toss some good data?

The motor cannon is also dependent on the disposition of the supercharger and attendant ancillaries. The reason why the Merlin could not carry a motor cannon was that the supercharger was large and in the way, while the intake piping was also in the way. In two stage engines there was also the aftercooler. It was a similar case for the Allison.

A flat engine may have less of a problem with intake runners and/or exhausts, but the supercharger may still be in the way.

Agreed here; the rear part of cannon can be aligned with rear part of the crankcase (with barrel protruding slightly more in front), so the 'engine-stage' compressor is avoided.

The Merlin's reduction gearbox was therefore able to be designe so as to give the minimum frontal cross section from the engine.

Any gearbox is anyway narrower than V engine it belongs, so no gain here?

 

[Trilisser]

Tomo, a lack of crankcase rigidity is a serious problem in any engine for it stresses the crankshaft as it is subject to excess flexing.

 

[tomo pauk]

Indeed, you're right. It would've been cool if someone has the good data covering the rigidity of the boxer engine crankcase whole engine.

 

[Shortround6]

A flat engine has very good rigidity in one dimension, not so good in the vertical. Think of a 1" X 9" plank vs 3" X 3" beam of the same length. the 1 X 9 will be very strong in line with it's width but no so good if bent vertically or in resisting twisting.

A bit simplistic but I hope the idea is there. This can also show up in engines by construction types. An engine that uses cast cylinder blocks is stronger than an engine that uses separate cylinders, like many air cooled engines and some old,old water cooled ones. a few engines tried a compromise, like the Napier Lion, one piece crankcase, separate cylinders, one piece heads trying to tie the Cylinders and block together.

Many engines that used one piece blocks needed beefed up crankcases as rpm and power went up.

You can design a strong enough flat engine, there just may be a weight penalty that wouldn't be there if a different shape was chosen.

There are dozens if not hundreds of trade offs made in engine designs.

 

[fastmongrel]

The problem with the 'W' engine is that it has a lot of frontal area. The Lion was about a foot wider than a Merlin and every bit as tall. Makes for a rather poor view over the nose. as for the 36 litres, are you talking about bigger cylinders or adding them for a W-18? With the 12 you can have a short, sturdy crankcase and crankshaft. Going to the 18 gives you a crankcase and crankshaft as long as the V-12 except you have the weight and complication of another cylinder bank.

I meant a totally new engine using all the latest technology like monobloc castings for the cylinder banks sodium exhaust valves, modern superchargers. Basically everything that DB, RR, Hispano and Allison were doing. With the width issue maybe it could have been the big bomber engine that the Vulture never quite became. Without the time spent on the Rapier and Dagger aircooled upright H engines and then the flat H Sabre the new alternate history Napier W 12 could have been in service roughly the same time as the Merlin. The Merlin could be the fighter and light bomber engine and the new Napier power medium and heavy bombers.

If the Luftwaffe had ever got round to flattening Rolls Royce Derby things could have got a bit tight for the RAF till the shadow factories and Packard got into the swing of things as it was so reliant on the Merlin powering current and future projects.

 

[wuzak]

A flat engine has very good rigidity in one dimension, not so good in the vertical. Think of a 1" X 9" plank vs 3" X 3" beam of the same length. the 1 X 9 will be very strong in line with it's width but no so good if bent vertically or in resisting twisting.

A bit simplistic but I hope the idea is there. This can also show up in engines by construction types. An engine that uses cast cylinder blocks is stronger than an engine that uses separate cylinders, like many air cooled engines and some old,old water cooled ones. a few engines tried a compromise, like the Napier Lion, one piece crankcase, separate cylinders, one piece heads trying to tie the Cylinders and block together.

Many engines that used one piece blocks needed beefed up crankcases as rpm and power went up.

You can design a strong enough flat engine, there just may be a weight penalty that wouldn't be there if a different shape was chosen.

There are dozens if not hundreds of trade offs made in engine designs.

The hyper engines used separate cylinder construction, and were liquid cooled. It was part of the hyper engine program specifications.

 

[Shortround6]

The hyper engines used separate cylinder construction, and were liquid cooled. It was part of the hyper engine program specifications.

True and it was one of the more questionable decisions or specifications. While it made the fabrication of test rigs or test engines easier it made the complete engine longer and heavier than it would have been if it was "block" engine. More distance between cylinder centers. Some other engines used separate cylinders but used a one piece sheet metal cooling jacket around a 6 cylinder bank so it has the apperance of a 'block' engine

 

[wuzak]

The Merlin's reduction gearbox was therefore able to be designed so as to give the minimum frontal cross section from the engine.

Any gearbox is anyway narrower than V engine it belongs, so no gain here?

The propellor shaft was positioned so it was in the centre of area of the engine when looking from the front. When it wa sinstalled in the airframe it gave less frontal area than otherwise, and thus less drag.

 

[wuzak]

While was thinner than some X designs it was actually wider than a Griffon which was almost the exact displacement. It was also quite a bit longer and almost 400lbs heavier (than a two stage Griffon). Weight to the Chrysler does not include turbo. There were a few questionable constructional choices but the decision to take the drive from the middle of the crankshaft points to the problem with V-16 engines.

The central power take off was good in that it reduced problems associated with the length of the crankshaft. In effect it became two V8s end to end.

Power take-off from the front would have probably caused lots of problems from the crank.

Daimler Benz also made a V16 (the 609?). Any idea to where the PTO was for that?

 

[Shortround6]

Some info in this thread : http://www.ww2aircraft.net/forum/engines/opportunity-lost-db-16-cyl-21836.html

 

[wuzak]

Some info in this thread : http://www.ww2aircraft.net/forum/engines/opportunity-lost-db-16-cyl-21836.html

Thanks for that Shortround.