1. The B17E had a service ceiling of 36600 ft but that did not mean it bombed from that altitude. I recently read a book by the lead navigator of the 100th bomb Group and they routinely bombed from 18000 feet. I know or knew a couple of B24 pilots and with a full load of ammo,fuel, and bombs they were doing good to get to 20000 ft. The F4U-4 had a service ceiling of over 41000 feet but they almost never operated at anything near that altitude. Yes, the B29s could and did bomb from 30000 or more but couldn't hit anything because of the winds aloft so had to bomb from much lower.
2. That is the reason that the KI84 that was not a true 400 mph fighter was quite effective against all our fighters.
1. B-17's in the ETO typically bombed from the low-mid 20's k ft. 18 would have been unusual though not unheard of, maybe you should cite the exact source. B-17's typically bombed from a bit higher than B-24's where low 20's would be more typical. The big difference there was vulnerability to AAA, considerably less at the higher range of typical altitudes, so 18k against heavily defended Reich targets doesn't sound right. The 8.8cm Flak 36/37, backbone of the German AAA right to end, had an effective ceiling around 26k, so the B-17's ability to get close to that practically, while maintaining sufficient course stability to bomb reasonably accurately in big formations (that's what limited B-24 altitudes) was one reason for the 8th AF's preference for the B-17.
However early in the war, in the Pacific, B-17's did in fact bomb from as high as 30k, small formations of unescorted bombers trying to avoid interception by JNAF fighters (see "Fortress Against the Sun" by Salecker for a number of examples).
The initial unescorted B-29 raids over Japan were from high 20's to just over 30. Then night raids starting March '45 much lower (low teens or even less); then escorted day raids starting in April were similar to ETO, low-mid 20's.
However, escort fighters are better off to be able to cover their bombers from above, altitude advantage is always desirable, and if the battle centers on bombers at 25k ft (as opposed to say torpedo planes at ~zero ft), the ability to bounce from ~30k is very useful. See Robert S Johnson's account in "Thunderbolt" of German fighters occasionally trying to sneak in on escorted formations from around 40k ft.
2. The practical speed of operational Ki-84's is still debated, but "quite effective" would be have to be based on Japanese claims repeated in Western books (kind of the inverse of the typical situation of underrating the earlier Japanese types based on continuously repeated inflated *Allied* claims). The real situation is somewhat fuzzier. Naturally with a big performance advantage the Ki-84 almost had to do better, but even the late Japanese types were pretty clearly on the short end of exchange ratio stick v. US fighters in the actual overall situation of 1945. Breaking out figures, accurately, by type is hard (they exist on the US side in some cases, but the radial Japanese fighter types were frequently mistaken for one another, esp late in the war with such a long menu to choose from, as is easily seen for the combats that can be identified in Japanese records).
Back to P-47N v. F4U-4: it reminds me of late mark Spit v P-51. Comparing in a vacuum is one thing, but the P-47N had the range for missions an F4U just couldn't perform, any plane is worth zero in the areas it can't reach. For example speaking of the P-47 over Korea it did operate there, at the end of WWII! The Marine Corsairs based in the Okinawa/Ie Shima airfields couldn't reach Korea, P-47N's could and flew missions there in the last week of the war, with good success against the JAAF Ki-84's based there. It's a moot point whether a Corsair could have done better.
Joe
plus of course the family she gave birth to............
