Essential and Dispensible WW2 aircraft.

On Oct 6, 4:09 am, Bill Shatzer wrote:
Daryl Hunt wrote:

-snip-

Keeping it in the whatif department. Whatif they had installed decent
Turbos and Supers on the Allisons. What would that have done for even the
P-40. Afterall, later productions on the P-38 and the P-47 would have had
equal or more range and speed of the P-51C and the P-40 would have had near
identical performance and speed.

Dunno. The Merlin equipped P-40F was only about 10 mph faster than the
earlier Allison-fitted P-40E - although obviously better at altitute.

But it still was more than 50 mph short of the P-51B/C's top speed.

I doubt a "super-Allison" would have produced markedly superior results
or placed the P-40 in the P-51's performance class.

The P-40 was, after all, basically an up-engined Hawk 75 (P-36), a 1934
design and a full generation earlier than the P-51 airframe design.

Cheers

As far as I can tell the Merlin engined P-40's used a single stage two
speed
supercharged Merlin equivalent to that used in the Spitfire Mk.V.
Both were 375 mph (approx) aicraft.

The Two stage 66 and 70 merlins added an intercooler and it was these
engines
that transformed both the P-51A to the 440mph P-51B/C/D and the
Spitfire
Mk.IX to a 408-412 mph aircraft.

Had the P-40 gotten the two stage Merlin it might have matched the
Spitfire
Mk IX in speed?

The modification would have required a lengtened nose to and
additional
radiator area to deal with the extra head and to dump heat from the
intercooler.

In article . com,
Eunometic wrote:

The modification would have required a lengtened nose to and
additional
radiator area to deal with the extra head and to dump heat from the
intercooler.

Liquid cooling an aircraft engine is like air cooling a submarine
engine...


;-

On 18 Oct, 00:51, Dan Nafe wrote:
In article . com,

Eunometic wrote:
The modification would have required a lengtened nose to and
additional
radiator area to deal with the extra head and to dump heat from the
intercooler.

Liquid cooling an aircraft engine is like air cooling a submarine
engine...

;-

What has liquid cooled engines to do with intercoolers?
And if liquid cooled engines are so bad why did every airforce want
liquid cooled engines for their fighters in WW2 (except the USN)?
some may have not had them in enough numbers (Italy, Japan) but they
wanted them.

Guy

In article om,
guy wrote:

On 18 Oct, 00:51, Dan Nafe wrote:
In article . com,

Eunometic wrote:
The modification would have required a lengtened nose to and
additional
radiator area to deal with the extra head and to dump heat from the
intercooler.

Liquid cooling an aircraft engine is like air cooling a submarine
engine...

;-

What has liquid cooled engines to do with intercoolers?
And if liquid cooled engines are so bad why did every airforce want
liquid cooled engines for their fighters in WW2 (except the USN)?
some may have not had them in enough numbers (Italy, Japan) but they
wanted them.

Guy

Liquid cooling lends itself to improved streamlining and improved
cooling distribution among the cylinders. Its main drawback is
vulnerability of the cooling system to debris and small arms fire.

In article
,
Orval Fairbairn wrote:

In article om,
guy wrote:

On 18 Oct, 00:51, Dan Nafe wrote:
In article . com,

Eunometic wrote:
The modification would have required a lengtened nose to and
additional
radiator area to deal with the extra head and to dump heat from the
intercooler.

Liquid cooling an aircraft engine is like air cooling a submarine
engine...

;-

What has liquid cooled engines to do with intercoolers?
And if liquid cooled engines are so bad why did every airforce want
liquid cooled engines for their fighters in WW2 (except the USN)?
some may have not had them in enough numbers (Italy, Japan) but they
wanted them.

Guy

Liquid cooling lends itself to improved streamlining and improved
cooling distribution among the cylinders. Its main drawback is
vulnerability of the cooling system to debris and small arms fire.

Oil coolers are every bit as delicate as radiators (but smaller and
therefore harder to hit with a golden bb). A hit in an oil cooler would
bring down an aircraft just as quickly as a hit in a glycol radiator.

Air cooled engines (in aircraft, not submarines) are lighter and less
complex to operate than liquid cooled engines.

In article , Dan Nafe
wrote:

Air cooled engines (in aircraft, not submarines) are lighter and less
complex to operate than liquid cooled engines.

WRT the weight...is that really true?
IME building liquid-cooled and air-cooled systems, the Liquid systems
are often lighter. Of course while glycol weighs more than air, usually
more aluminum is needed in an air-cooled system than in a liquid-cooled one.

--
Harry Andreas
Engineering raconteur

On Fri, 19 Oct 2007 09:50:00 -0700, (Harry
Andreas) wrote:

In article , Dan Nafe
wrote:

Air cooled engines (in aircraft, not submarines) are lighter and less
complex to operate than liquid cooled engines.

WRT the weight...is that really true?
IME building liquid-cooled and air-cooled systems, the Liquid systems
are often lighter. Of course while glycol weighs more than air, usually
more aluminum is needed in an air-cooled system than in a liquid-cooled one.

I'd thoiught that weight was about the same. Frontal area (less
air resistance) favoured water-cooling but reliability favoured
radials.


Peter Skelton

On Fri, 19 Oct 2007 09:50:00 -0700, (Harry
Andreas) wrote:

In article , Dan Nafe
wrote:

Air cooled engines (in aircraft, not submarines) are lighter and less
complex to operate than liquid cooled engines.

WRT the weight...is that really true?
IME building liquid-cooled and air-cooled systems, the Liquid systems
are often lighter. Of course while glycol weighs more than air, usually
more aluminum is needed in an air-cooled system than in a liquid-cooled one.

From my reading it looks like you've got two issues:

Weight. It looks like early on the liquid cooled engines (like the
Merlin) could deliver more performance than single-banked radials
(like the R-1820). As time went on, however, the radials improved HP
output without much growth in weight. The version I'm most famliar
with, the R-1820-56 series, could put out 1525 hp (only slightly less
than an early Merlin). The double-banked radials (like the R-2800)
could significanly better the Merlin, but at a significant weight
penalty.

I've not looked at later liquid cooled models like the Griffin, nor
any of the Axis production engines.

Reliability. While you can probably get a better power to weight
ratio from a liquid cooled engine, the cooling system is an "achilles
heel" for the type. There are numerous stories (ranging from the
beginning of WWII to all the way to the end of the Viet Nam War's
A-1s) of radial engined aircraft coming back home with massive engine
damage (no oil, cylanders shot away, etc.).

Performance was certainly an issue and the larger frontal area of the
air-cooled engine puts it at a disadvantage vis-a-vis the liquid
engine. But, then, naval aircraft are generally at a slight
disadvatage when comparted to comparable land-based types due to the
additional weight penalty that navalization extracts (heavier overall
structure, heavier undercarriage, wing fold systems, etc.).

A liquid cooling system adds a significant level of complexity, and
thus maintenance cost (dollars and man hours). Ships cannot carry
unlimited numbers of mechs or spares so this complexity is a major
consideration.

A "quick and dirty" overview of the naval aviation establishments of
the WWII era demonstrates a dramatic favoring of air-cooled engines
over liquid cooled engines. The U.S. didn't have any liquid cooled
carrier aircraft; the British were mixed about 50-50 in type but I
can't get a firm grasp on numbers (large numbers of U.S. manufactured
aircraft like the Avenger and Corsair were used); the Japanese had a
very few liquid cooled types, but air-cooled predominated; I don't
have any good information on the French.

Overall, for naval use from carriers, the air cooled engine is the
clear winner.

guy wrote:

On 18 Oct, 00:51, Dan Nafe wrote:

In article . com,

Eunometic wrote:

The modification would have required a lengtened nose to and
additional
radiator area to deal with the extra head and to dump heat from the
intercooler.

Liquid cooling an aircraft engine is like air cooling a submarine
engine...

What has liquid cooled engines to do with intercoolers?
And if liquid cooled engines are so bad why did every airforce want
liquid cooled engines for their fighters in WW2 (except the USN)?
some may have not had them in enough numbers (Italy, Japan) but they
wanted them.

Well, "every airforce" would seem something of an exaggeration.

The Soviet La-5FNs and La-7s, the US P-47s, the radial-engined German Fw
190s, and the Japanese Ki-84s, Ki-100s, and N1K2-Js were certainly more
than satisfactory fighters for their respective air forces.

The British seemed to go mostly with inline liquid cooled engines for
their fighters but even there, the post-war Sea Fury (arguably the best
piston-engined fighter ever) provides an obvious exception.

Cheers,

guy wrote:

Responding late, but a few points:

On 18 Oct, 00:51, Dan Nafe wrote:
In article . com,

Eunometic wrote:
The modification would have required a lengtened nose to and
additional
radiator area to deal with the extra head and to dump heat from the
intercooler.

Liquid cooling an aircraft engine is like air cooling a submarine
engine...

;-

What has liquid cooled engines to do with intercoolers?
Nothing. Highly supercharged engines (Pressure Ratio of more than 3.0)
really benefit from removing as much of the heat that's generated by
compressing that air as possible, though. Some airplanes used cold air
(P-38, P-47, B-17, B-24, B-29) to do that, some (2 Stage Merlin) used
liquid.

And if liquid cooled engines are so bad why did every airforce want
liquid cooled engines for their fighters in WW2 (except the USN)?

Well, a couple or 3 reasons. With a smaller frontal area, it was felt that
an inline engine would be more streamlined, reducing drag.
It was also thought that a liquid cooled engine would have better heat
rejection - you just wouldn't be able to run an air-cooled engine at high
power due to insufficient cooling.
and last, but not least, fashion happens as much in Aviation as it does
anywhere else. Pointy airplanes look cool, so people like to design pointy
airplanes.

As it turns out, you lose most, if not all of the frontal area advantages of
a liquid cooled engine because you need to have radiators sticking out in
the breeze to keep the coolant temperature within tolerable limits.
As an example, consider a comparison between the aircooled P-47, and it's
liquid cooled British equivalents, the Typhoon and Tempest. They have
almost the same frontal area. In the case of the Typhoon and Tempest, half
of it is radiators.
It's possible to build low drag cooling systems, like that of the P-51
(Especially the B models and up), but it requires long ducting to act as a
diffuser, a large radiator that, because of the ducting, will have to be
buried in the structure, and a converging outlet to accelerate the heated
air.
The idea that an air-cooled engine couldn't get rid of heat fast enough was
based on the idea that you couldn't put enough fin area on a cylinder to
get rid of the heat. In the U.S., both Wright and Pratt & Whitney
developed methods of making fins thinner and closer together, and with
special shapes,to give more cooling area.

--
Pete Stickney
Without data, all you have is an opinion