FW-190 A5 Speed@sea level.

[BnZs]

I think there is a fair amount of evidence that the current deck speed for the 190A5 (339mph) is 8-12mph too slow.

http://www.wwiiaircraftperformance.org/fw190/fw190a5.html



 

[J.A.W.]

Correct, & the same also applies to the Typhoon..

[bozon]

The F6F is too slow at its FTH by almost 20 mph.

[Fish42]

What octane rating fuel did they use for those tests?

You have to make sure they are not using the higher grade fuels that HTC has not modeled. 100/130 Octane is the highest modeled. 150 Octane would give many Mid/Late war a big boost.

During 1942 and 1943 the British were testing aviation fuels that allowed for higher engine powers in their fighter aircraft than was possible using the standard 100/130 grade aviation fuel then in use.

Testing of a Spitfire IX by Rolls Royce, Hucknall in October 1943 determined:

    The increase of boost pressure to 25 lbs/sq.inch provides a considerable improvement in the low altitude performance of the Spitfire IX aircraft, the necessary modifications to achieve this being comparitively simple. 1

The same aircraft was tested by the Aircraft and Armament Experimental Establishment (A.& A.E.E.), Boscombe Down in November 1943, the conclusion being:

    An increase of about 950 ft/min in rate of climb and about 30 mph in all-out level speed is achieved by the increase of boost from +18 lb/sq.in. to +25 lb/sq.in. 2

The Germans and US had similar fuels to allow higher boost. Japan I think suffered from poor quality fuels for the whole war*.

*99% sure.

http://www.wwiiaircraftperformance.org/150grade/150-grade-fuel.html

[J.A.W.]

150 PN/Grade avgas was introduced in the ETO for the invasion/V1 assault defence in mid `44..

Enabling Merlin Mustangs to run +25lbs/72in boost..

[GScholz]

Fw 190A's ran on C3 fuel, the best fuel the Luftwaffe got, equal to 100/130 octane in mid-war, and 100/150 octane late in the war. The BMW 801 D-2 engine couldn't use the lower grade B4 fuel that the 109's were using.

[J.A.W.]

Air cooled radial mills were less able to tolerate/reject heat than liquid-cooled types..

Nor could they utilize efficient liquid cooled inter/after-cooling for their superchargers,
& so ran lower boost levels..

The BMW powered 190s injected extra C3 into the supercharger as charge coolant too..

[GScholz]

Air cooled radial mills were less able to tolerate/reject heat than liquid-cooled types..

Nor could they utilize efficient liquid cooled inter/after-cooling for their superchargers,
& so ran lower boost levels..

The BMW powered 190s injected extra C3 into the supercharger as charge coolant too..

I'm not sure how that's relevant to the discussion?

[J.A.W.]

Relevance?

Gives technical background for BMW/FW 190 need for C3..

[Scherf]

Fw 190A's ran on C3 fuel, the best fuel the Luftwaffe got, equal to 100/130 octane in mid-war, and 100/150 octane late in the war. The BMW 801 D-2 engine couldn't use the lower grade B4 fuel that the 109's were using.

Wouldn't say it was equal - octane rating at rich mixture was identical, as the mix leaned out C3's octane rating fell away considerably.

[GScholz]

Wouldn't say it was equal - octane rating at rich mixture was identical, as the mix leaned out C3's octane rating fell away considerably.

Ok. However the reason the Germans ran larger displacements with lower boosts was their use of fuel injection. This is also why Rolls Royce chose to continue with carburetors. Which was the right choice is a technical debate not suited for this thread.

[J.A.W.]

Its true, & its another reason the BMW needed extra for high power loadings..

[GScholz]

Wouldn't say it was equal - octane rating at rich mixture was identical, as the mix leaned out C3's octane rating fell away considerably.

Rich is the only thing that matters for max power (anti-knocking). Lean is important for cruise performance. What was important for the German interceptors? What was important for the Allied escort fighters? (Rhetorical questions.) Each side engineered their fuels to better suit their needs.

[BnZs]

The maximum speed for the 190-A5 is spot on in agreement with these figures per the AH performance charts. So that would seem to suggest that no, these tests weren't "hotrodding" with fuel not modeled in AHII

What octane rating fuel did they use for those tests?

You have to make sure they are not using the higher grade fuels that HTC has not modeled. 100/130 Octane is the highest modeled. 150 Octane would give many Mid/Late war a big boost.

The Germans and US had similar fuels to allow higher boost. Japan I think suffered from poor quality fuels for the whole war*.

*99% sure.

http://www.wwiiaircraftperformance.org/150grade/150-grade-fuel.html

[GScholz]

The maximum speed is limited by the supercharger at full pressure height. An increase in allowed boost would only affect speed below FPH. The 190A-5 had increased boost at WEP later in the war, but I guess HTC models an early A-5. AH's A-5 matches the performance at ~1.35 ATA boost.