Sun Jul 23, 2017 10:46 pm
The B-19 had an internal bomb load of 18,700 lbs (it would not carry externals on long range missions). That makes its typical wartime bomb load around 15,000-16,000 lbs.
The B-29 typical wartime bomb load was 20,000 lbs. As mxaxai already mention, the B-29 was faster than the B-19, by a lot. Fighter pilots love big slow targets.
The B-19 required a crew of 18, while the B-29 had a crew of 10-11. There was also some doubt by Gen. Arnold and MGen. Groves the B-19 could take the Silverplate modifications. In 1943 the USAAF knew there were only two airplanes in the world that could deliver the two different Atomic Bombs that were then in development, the USAAF Boeing B-29 and the RAF Avro Lancaster Mk. I Special. Gen. Arnold wanted an American built bomber to deliver the A-Bombs, so the Lanc was out of consideration.
Silverplate (aka Saddletree) B-29s differed from their B-29 sisters by having most guns and armor removed, the two bomb bays converted into one long bomb bay, new bomb shackles, new bomb release system, provisions to arm the bomb after take-off, and the last batches of WWII built Silverplate B-29s had fuel-injected Wright R-3350-41 engines for improved performance.
Of the 46 Silverplate B-29s built during WWII, 29 were assigned to the 509th Comp Gr. and of those 15 were designated as combat airplanes that would be used to deliver the A-Bombs, the other 14 were flown on combat missions, just not involving the A-Bomb missions (the A-Bomb mission aircraft included Enola Gay, Bockcar, Great Artist, weather, and photo planes).