Re: AIR Question - Razorback vs Bubbletop



It was a while before large one-piece blown clear parts became common. The early B-17s had framed nose pieces and didn't get a one-piece nose until the the B-17F model, which came out in about 1942.
Dave
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It was a matter of aerodinamycs. "Razorbacks" induce noticably less drag than "bubbletops". If memory serves me well, the max.speed difference between P-51B and P-51D is about 20 km/h (if not more) in favor of the "razorback" one, for P-47s the difference is even larger.
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With the P-51B, top speed is usually listed as 440 mph, while it's 437 for the P-51D, or about a 5 kph difference. It might have been more severe with the P-47, but I don't have the data to compare the P-47D-23 and D-25. The first front-line fighters with all-round vision canopies were the Westland Whirlwind, A6M Zero and Ki. 27, but these were all more-or-less heavily framed (as were the nose cones of all B-17s up through the B-17E). The first clear-blown canopy on an operational fighter was probably the Typhoon (the first P-47 with a bubble canopy used the Typhoon canopy). The technology to create canopies like this was perfected during the war, and probably coincided with the realization that the pilot required increased visibility. There may also have been an issue with turnover protection for pilots which militated against the shift.
Mark Schynert
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Most any a/c with the straight back will be faster than it's non-straight-backed brother. Even holds true for Cessnas. The older straight-backed 150s, 172s & 182s are a bit faster than their later versions with the rear windows.
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Some of it was probably just keep on doing like we always have. Many early open cockpits planes had a neck protection or roll bar to protect the pilot. Boeing P-12E and P-26 for example. When the started covering the cockpit it was probably a question on closing what was already there. Look at the P-51 all up to the D, Corsair Birdcage, Hellcat, Warhawk and Thunderbolt early versions, they all had "rear side windows" or quarter windows to improve visibility. Only the two navy planes really stayed the same except these, the only Corsair with Bubbletop was the Goodyear FG-2. The rest seems to have had a higher priority for allround view. Actually was used long after the war, just look how many early MIG jets had it, or the swedish SAAB fighters. Different priorities and some technique.
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Claus Gustafsen
Strandby, Danmark
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