davparlr
Senior Master Sergeant
Spitfire Performance test show Mk II and IV with a top speed of around 366 mph.
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Point of Order: even the earliest Mossie bombers did 380 minimum. FB Mossies also replaced Havocs on the Intruder squadrons - the difference in effectiveness speaks for itself, have a look at 418 Squadron, the 23 Sqn ORB is also online. From memory, it took 418 a year and a half to accumulate seven kills with the Havoc, doubled that in just over a month and a half with the Mossie.
Not quite.
The earliest bomber Mosquitos, the B Mk IV with Merlin 21 engines, managed around 365-370 mph. This was due to the effect of the ducted 'saxophone' exhausts to hide the exhaust flames during night.
When these were ditched in favour of multi ejector stubs, and a few minor other aerodynamic refinements were incorporated, speed went up to about 380 mph when loaded and about 385 mph with stores out.
Not sure what to tell you - all the data cards I've seen for the PR.I and the B.IV give a top speed of 380 or above. Sharp and Bowyer give the same numbers both for the prototypes and early production B.IVs.
Only test I've ever seen with a B.IV top speed less than 380 was on DK290, when +9 lbs boost was used. Those tests were done starting December '42, despite 105 Squadron using +12 to give German fighters the slip from July '42 at the latest. Sharp and Bowyer also have a chart of Merlin power increases with the XX at +12 by mid-1940.
You now (using Allisons) have a much bigger, higher drag airplane than a P-38 (without turbos?) with little more internal fuel.
Hmm, might well have to read up on my Merlins then, either that or find earlier data cards...
(Can you recommend a good Merlin book?)
Thanks for that - I re-checked all the data cards and pilot's notes I have, they all give the M21 with +14 in M gear and +16 in S for everything that uses the Merlin 21. The pilot's notes say +12lbs was available by pushing back the spring catches on the throttle, which otherwise held the throttles at climbing boost (+9 lbs), but that this +12 was available at sea level only. Greater boost levels (+14 and +16, as above), were available through pulling the boost control cut-out, which was located on the top-left of the instrument panel.
I know for a fact the cut-out was available in early September at the latest, as a weather recce Mosquito was jumped by two 190s at high level - the Mossie got away with it but the pilot was noted to have failed to pull the boost control cut-out, which would have increased his speed below 22,000 feet. That's precisely where DK290's speed peaks, and where it's boost lilne goes "flat" on the test report. Pretty much identical to the W4076 test. The data cards for the Merlin 21 aircraft show a maximum speed at 14k (S gear) at or just above 380 m.p.h.
Do you have a source for me re: boost on the 21?
Still really don't know what to make of timing re: boost and ejectors. The Mossie history has nineteen Mossies on 105 Sqn by the end of September '42, "all with 14 lb. boost." It seems they were doing their own testing in situ, including substituting stubs for saxophones, which took place on DK336 at Marham, the 105 Sqn base, as opposed to Boscombe Down. (DK336 GB-P appears with stubs in a number of the pics taken at the "press day" at Marham, IIRC 5 December '42.)
I wonder if part of the reason the USA never built the Mosquito was a disinclination to adopt another nations designs. As the world's pre-eminent industrial power the US politicians and procurers might have found it a little hard to accept that someone was doing a better job of producing a particular type of aircraft than they were. I seem to recall there was a fair bit of teeth gnashing when the USMC adopted the Hawker Harrier. That said, the US did use Spitfires and Mossies and doubtless a few others I haven't mentioned, so perhaps they never really saw a need for the wooden wonder
Not sure what to tell you - all the data cards I've seen for the PR.I and the B.IV give a top speed of 380 or above. Sharp and Bowyer give the same numbers both for the prototypes and early production B.IVs.
Only test I've ever seen with a B.IV top speed less than 380 was on DK290, when +9 lbs boost was used. Those tests were done starting December '42, despite 105 Squadron using +12 to give German fighters the slip from July '42 at the latest. Sharp and Bowyer also have a chart of Merlin power increases with the XX at +12 by mid-1940.
Thanks for that. Begs the question why A&AEE were testing at +9 from December '42 to April '43 when +16 had been approved in November. Maybe absolute speed itself wasn't the main issue - more the differential 'twixt saxophone and stubs, matt and gloss.
Still really don't know what to make of timing re: boost and ejectors. The Mossie history has nineteen Mossies on 105 Sqn by the end of September '42, "all with 14 lb. boost." It seems they were doing their own testing in situ, including substituting stubs for saxophones, which took place on DK336 at Marham, the 105 Sqn base, as opposed to Boscombe Down. (DK336 GB-P appears with stubs in a number of the pics taken at the "press day" at Marham, IIRC 5 December '42.)
Tantalisingly, the conclusion is that stubs were good for daylight ops, "as on reconnaissance aircraft". As you know doubt know, the original PR Mossies had the one-piece cowlings, however DK310 force-landed in Switzerland with radiator and engine strife in August had saxophones, and was photographed there (next to a German 109!). The first PR VIII (Merlin 61s) also had stubs in October '42.
Thanks again for the info.
<grabs popcorn>
You have to remember the US was a very different place back then. Yes it was the world largest economy by that time, but in many technological areas it was very far behind. Aerodynamics, engines, superchargers, electronics, weapons, etc, etc, etc.
So behind that Bren carriers were powered by copies of the Ford V-8 car engine? British Motor torpedo boats used Packard engines? Other British launches used Hall-Scott engines? British army used American trucks for heavy hauling?They had a tremendous potential capacity, because of the large motor vehicle, radio, etc industries, but were well behind Europe technologically.
Rather ignores the GE J-35 and Westinghouse engines doesn't it?Even post war,the US had to use and/or license Rolls Royce jet engines because it couldn't design/make any itself. Basically it did a Jaapan/China thing. Copy and build foreign designs and then later make its own designs.
In many ways and many areas it was still a 2nd World nation, with areas of concentrated (and very large) industries, but many other areas of incredible poverty and, basically, primitiveness. Take one example, the national road system was virtually non-existent, that came later in the Eisenhower era. If you read, for example, Yeager's biography about the standard of living when he was growing up, not that much different from an (say) eastern European peasant of the time.