(Peter Stickney) wrote in message ...
In article ,
Dave Eadsforth writes:


No, As with anythig else in Aviation (Or any other Engineering), it's
a balancing act. You can only get so much of a compression ratio out
of a Supercharger, for any given drive speed. In order to get more
boost, you've got to start with thicker air, so the Critical Altitude
actually decreases. When you're chasing V-1s, though, or fighting
against Me 109s, or Fw 190s, that's not a bad thing. The Daimler Benz
engines in the 109, by virtue of their variable-speed blowers, which
didn't require as much power to run at low altitudes, gave a big
advantage down low. The BMW 801 on an Fw 190 had a geared blower, but
the critical altitude for the low gear was very low, down near Sea
Level.
In order to improve altitude performance, you've got to increase the
compression ratio of the induction system, or add an axidizer to the
fuel-air mix to help it burn. This can be done by adding supercharger
stages (Basically one supercharger feeding another, like, say, a
Merlin 60 series engine, or the turbosupercharger/engine driven blower
setups on the P-47 and P-38, or piping something like Nitrous Oxide
into the induction system, as the Germans did.

The drawback is that
it takes more of hte engine's power, in the gear-driven examples, to
compress the air that much more. That means that at lower altitudes,
you're at a disadvantage. Or, you've got got to haul around a bunch
of tanks, regulators, pipes, valves, & all that for teh Nitrous
system. You've only got a limited quatity of Nitrous aboard, and you
can pretty much guarantee that it'll run out right when you need it.
Or, worse yet, the storage bottles could get damaged. Leaking
Oxidizers is a Bad Thing, especially when somebody's shooting at you.

More later, with real numbers attached.


Nitrous oxide was more a technique the Germans were forced into to
help overcome a German disadvantage in high octane or high test
aviation fuels rather than a paucity in thingking.

The Germans did have techniques for manufacturing octane and even
higher knock hydrocarbons their technology was however more cumberson
than the US technology and this limited their production rate. Why
this was I don't know. It may have had something to do with the fact
that they had access to only snythetic oils from fischer tropsch and
hydrogenation plants or their own small crude oil industry or
Romania's all of which are regarded as poor quality crudes.
(California crude was rather highly regarded). It may have just been
that they were unaware of the US techniques.

Nitprous oxide also was used only at higher altitudes: water methanol
injection was used at low altitude.

The Ta 152H has a watern methanol and nitorous oxide system. The
clipped wing Ta 152C has only water methanol for its BB603LA

The Jumo 213E had a two stage 3 speed supercharger WITH an induction
cooler. It still had water methanol and nitorus oxide (nickamed HA HA
system because Nitorus oxide was laughting gas)

Ta 152H Engine: Junkers Jumo 213E-1 twelve-cylinder liquid-cooled
engine rated at 1750 hp for takeoff (2050 hp with MW 50 boost) and
1320 hp at 32,800 feet (1740 feet with GM 1 boost). Maximum speed: 332
mph at sea level (350 mph with MW 50 boost), 465 mph at 29,530 feet
with MW 50 boost, 472 mph at 41,010 feet with GM 1 boost. Service
ceiling was 48,550 feet with GM 1 boost. Initial climb rate was 3445
feet/minute with MW 50 boost. Weights were 8642 pounds empty, 10,472
pounds normal loaded, 11,502 pounds maximum. Wingspan 47 feet 41/2
inches, length 35 feet 1 2/3 inches, height 11 feet 0 1/4 inches, wing
area 250.8 square feet.

The Ta 152C-1 was powered by a Daimler-Benz DB 603LA twelve-cylinder
liquid cooled engine rated at 2100 hp (2300 hp with MW 50) for takeoff
and 1750 hp at 29,530 feet (1900 hp at 27,560 feet with MW 50). Armed
with one engine-mounted 30-mm MK 108 cannon with 90 rounds, two
fuselage-mounted 20-mm MG 151 cannon with 250 rpg, and two
wing-mounted 20-mm MG252 cannon with 175 rpg. Maximum speed was 227
mph at sea level (356 mph with MW 50), 436 mph at 37,730 feet (460 mph
at 32,810 feet with MW 50). Initial climb rate was 3050 feet per
minute and service ceiling was 40,350 feet. Weights were 8849 lbs
empty, 10,658 lbs normal loaded, and 11,733 pounds maximum. Wingspan
was 36 feet 1 inch, length was 35 feet 6 1/2 inches, height was 11
feet 1 inch, and wing area was 290.89 square feet.