Recent content by Hop

It was definitely a Vokes filter. The Australians spent some time building and testing their own replacement tropical cowling to replace it (they got a slight performance improvement but had problems with rough running at high altitude). Various figures for Spitfire V aircraft with Vokes...

The test notes say it was tropicalised, the statement on the condition of the aircraft makes no mention of the filter being removed. They also say "during the tests the engine limitations as stated in the handbook were adopted". I suspect they were simply using an original handbook, rather than...

British tests usually corrected figures to standard atmospheric conditions. The Australian tests I have seen, including the test of the tropicalised Spitfire V with and without drop tanks, did so as well. The Australian test of the clean Vc produced a speed of 334 mph at 15,000 at 3000 rpm, 9...

Richard G Davis, who was (may still be) the official historian of the USAF, says that the USAAF deliberately changed the "city area" category to "marshalling yard" as a means of claiming they weren't area bombing, but continued to carry out area attacks anyway. From his biography of Spaatz: A...

There's a list of the average cost of British bombers in: https://ses.library.usyd.edu.au/bitstream/2123/664/2/adt-NU20050104.11440202whole.pdf

On sortie rates, from Eagle in Flames by Hooton: Luftwaffe sorties: Aug 5-11 2,700 Aug 12-18 5,875 Aug 19-25 3,150 Aug 26-1 6,625 Sep 2-8 6,075 Sep 9-15 3,650 Sep 16-22 3,100 Sep 23-29 3,400 The three peak weeks for Luftwaffe fighter sorties were Aug 12-18 3,825 Aug 26-1 4,700 Sep 2-8 4,050...

There are RAF breakdowns of losses available. For example, The Narrow Margin has figures for August and September: Spitfires and Hurricanes Accident - 66 Enemy action on ground - 23 In action - 696 I'm not sure how comparable the figures are, though. The RAF's figure show less than 9% of...

The maximum internal load for the B-17 was 12 x 500 or 6 x 1,000. They didn't have the stations to carry more. The maximum internal weight of bombs was made up of 8 x 1,600, but the 1,600 lb bomb was armour piercing and very rarely used (just over 1,000 dropped in Europe during the war)...

It doesn't specify which type of 4,000 lb bomb, but the only likely options were the 4,000 lb High Capacity (cookie) or 4.000 lb Medium Capacity. The Mosquito could drop either, but according to Harris, the MC bomb wasn't used much by the heavies, and most were dropped by Mosquitoes. The two...

The cookie was very effective against structure and machinery. From the USSBS, describing attacks on refineries: and

Can you point to these tests?

NACA 868 uses roll performance figures for a Spitfire V.

And Mach. The Mach speed was usually the limiting factor at higher altitude. For example, from the P-47N manual, max IAS dive speeds in mph: Sea level - 564 10,000ft - 482 20,000ft - 400 30,000ft - 318 For the Spitfire IX: SL - 20,000ft - 450 20 - 25,000ft - 430 25 - 30,000ft - 390 30 -...

I believe by 1943 nearly all the aviation fuel used in the UK was imported from the US or US controlled sites in the Caribbean. In the summer of 1943 the US changed the formulation of 100/130 fuel in order to increase production. They increased the lead content from 4.8 cc per imperial gallon...

Madison does give figures for national GDP, but corrected to 1990 dollars. In 1939 France - $200,840,000,000 Austria - $27,250,000,000 Germany - $374,577,000,000 UK - $300,539,000,000 Comparing German absolute and per capita GDP suggests the figures for Germany do not include territorial...