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Greg at 'Greg's Airplanes and Automobiles' made this video comparison between P-51D and Fw 190D-9 back in July.
I find the video very good up until 30-th minute mark, unfortunately some things don't add up, like the 100 oct fuel giving 30 mph speed increase for RAF fighters during the BoB at high altitudes, or that turbo was 1st stage of compression on B-17s or P-47s. The notion of simply adding a second S/C stage to an existing engine is also not right IMO; ditto for referring of the auxiliary stage on 2-stage P&W engines as being 'remotely installed'.
Implying that USA was supplying the British with 100 oct fuel while circumventing their own law? Comparison of P-51A from mid-1943 vs. Spitfire V of mid-1941; no advantage of V-1650-1 vs. V-1710-39??
The best is jet to come - erstwhile Merlin was 'sucking hind tit', and didn't became the great engine until it used American fuel, American carb and American-derived if not designed supercharger?? (about min. 41 of the video)
Or it might be just me being me, the old nitpicker
... unfortunately some things don't add up, like the 100 oct fuel giving 30 mph speed increase for RAF fighters during the BoB at high altitudes ...
or that turbo was 1st stage of compression on B-17s or P-47s. The notion of simply adding a second S/C stage to an existing engine is also not right IMO; ditto for referring of the auxiliary stage on 2-stage P&W engines as being 'remotely installed'.
Implying that USA was supplying the British with 100 oct fuel while circumventing their own law?
I don't know about the 30 mph stuff but I had read somewhere that the Germans were surprised by the performance of the spitfire until one was downed in occupied territory and an analysis of the fuel revealed it was 100 octane.,
I'm not sure of your question here. Certainly the P-47 had a single speed, single stage engine mounted supercharger which was in turn fed by a second supercharger powered by exhaust (turbo-supercharger) mounted remotely behind the pilot. I suspect the P-38 was the same. Don't know about the B-17/24. It is true that a two stage two speed PW R-1830 was delivered for F4F-3 in early 1939. Whether this impacted RR on their engine I don't. Relations between British and American weapons manufacturing during this period of time probably warrants a doctoral thesis.
I've made a mistake there - Greg notes the turbo as being second stage, not the 1st stage I've wrote. (corrected now)
RR (and anyone else) knew about advantages of more than one stage of supercharging, since there were well-published altitude records achieved by aircraft powered by Bristol and Junkers engines with 2 stage S/C in 1936 or so - well before P&W made their 2-stage S/Cs. There was also the French suggestion for an single shaft 2-stage S/C published in 1938. Trick was getting the 2-stage superchargers packaging to be compact enough for use in fighters of the day, while getting acceptable reliability.
100 Octane fuel allowed for Merlin III 12lb boost at ~10K ft, and gave about a 30mph increase at that altitude. Approval of 12lb boost was given in Nov 1939:
http://www.wwiiaircraftperformance.org/hurricane/hurricane-12lbs-14nov39.jpg
above 10K ft, boost levels would decrease steadily and at ~18K ft would decline to 6lb of boost which was the rated 87 octane boost for the engine.
Nobody disputed that 100 oct fuel enabled a lot of power at lower altitudes, with corresponding increase of speed. What put me off was the claim that 100 oct fuel enabled extra 30 mph at higher altitudes.
Nobody disputed that 100 oct fuel enabled a lot of power at lower altitudes, with corresponding increase of speed. What put me off was the claim that 100 oct fuel enabled extra 30 mph at higher altitudes.
Apparently, 100 octane fuel manufactured in various places was being supplied to GB in 1939. I have read that Spitfires were not upgraded to 100 octane until March, 1940. It is not hard to believe Roosevelt was capable of circumventing laws, although I did read that some shipments were held up.
All part of the drift from peace to war,I vaguely recall something about charging an extra $1 per barrel, by the end of 1940 the USA and UK were in discussions to harmonise what 100 Octane actually meant.Apparently, 100 octane fuel manufactured in various places was being supplied to GB in 1939. I have read that Spitfires were not upgraded to 100 octane until March, 1940. It is not hard to believe Roosevelt was capable of circumventing laws, although I did read that some shipments were held up.
This document, page two initial paragraph, refutes your referenced document. I would guess that the first documents authorizes the use of 100 octane, the latter document references the implementation of the use of 100 octane.Fighter Command had approval to use 100 octane fuel in Sept 1938:
http://www.wwiiaircraftperformance.org/100-octane/24sept38-spitfire-100oct-approval.jpg
This document, page two initial paragraph, refutes your referenced document. I would guess that the first documents authorizes the use of 100 octane, the latter document references the implementation of the use of 100 octane.
http://www.wwiiaircraftperformance.org/100-octane/banks-fuel.pdf
A possible source of confusion on the "american" 100 octane fuel is that any fuel coming from the western hemisphere was sometimes referred to as coming from the "Americas" with the "S". The British were getting a lot of their 100 octane fuel from the west indies (Trinidad-Tobago) and not from United States of America refineries in 1939-40-41.
US Military standard 100 octane fuel of 1939-40 might not have allowed quite the amount of boost that British 100 octane did in 1940. They did not come up with a common fuel specification until after the BoB.
One more comment. While the author compares the P-51D, with racks, to the Fw 190D-9, which is reasonable because the P-51 most likely got to the battle area with drop tanks, an airframe to airframe comparison i.e., clean wings, 5 to 10 mph would have to be added to the P-51 speeds.
I don't know about the 30 mph stuff but I had read somewhere that the Germans were surprised by the performance of the spitfire until one was downed in occupied territory and an analysis of the fuel revealed it was 100 octane.,
SNIP
Apparently, 100 octane fuel manufactured in various places was being supplied to GB in 1939. I have read that Spitfires were not upgraded to 100 octane until March, 1940. It is not hard to believe Roosevelt was capable of circumventing laws, although I did read that some shipments were held up.
A possible source of confusion on the "american" 100 octane fuel is that any fuel coming from the western hemisphere was sometimes referred to as coming from the "Americas" with the "S". The British were getting a lot of their 100 octane fuel from the west indies (Trinidad-Tobago) and not from United States of America refineries in 1939-40-41.