(4 of 5)
Losses per month of 3,000-plane task force. To deliver 30-50,000 tons of bombs per calendar month requires that a maximum of about 15,000 bombers shall contact the targets. The present loss rate of 4% would therefore require maximum replacements of 600 planes per calendar month to maintain continuous bombing. Losses in pilots, crews, etc., at this rate, over a six months period might total about 25,000 men.
The joint U.S.-British output of planes and crews will exceed the above replacement rate by the end of 1942.
The facts so far summarize as follows:
In a 120-day period following decision to open the offensive, the United States and Great Britain can assemble a Joint Task Force of over 3,000 long-range bombers, can replace them at the rate of 600 per month, can equip them with trained crews, can drop 30,000-50,000 tons of bombs per month on any and all German targets, can maintain this performance indefinitely.
Effect
The effect of this campaign obviously cannot be forecast with precise mathematical accuracy. However, it can be estimated very closely by comparison with the results achieved by the enemy upon British cities, where the tonnage of bombs dropped was reliably estimated, and with the results achieved by the recent R.A.F. mass raids. The effect of a continuous campaign can also be estimated as an extension of the raids on Bremen, Mainz, etc.
Destructive Power
The object of most weapons is to detonate an explosive in the face of the enemy, whether the explosive is fired from tanks, mobile artillery, siege guns, or destroyers, cruisers and battleships. Viewed in this light, bombing is the equivalent of long-range gunfire. In place of a maximum range of 25 miles, it can carry explosives 1,000 miles and plant them even at night with fair accuracy. Because the missile does not have to be fired from a gun, the casing is light and the comparisons are:
Explosive contained in largest
(15") demolition shell . . . . . . . . . . . 152 Ib.
Explosive contained in torpedo. . . . 450 Ib.
Explosive contained in 2,000-lb.
bomb . . . . . . . . . . . . . . . . . . . . . . 1,100 lb.
Effect increases enormously with weight, due to increased blast. Furthermore, the bigger the bomb, the less proportionate weight goes into the casing. Thus:
250-lb. bomb, effect: local damage
2,000-lb. bomb, effect: destruction of everything over an area of 25,000 sq.ft. and severe blast injury to everything over 75,000 sq. ft.
The mixed effect of 500, 1,000 and 2,000-lb. bombs, as now used in mixture of explosive and incendiary, when measured by actual blast and fire areas, is such that requirement for complete destruction is estimated to be about 300 tons per square mile. Complete reduction to rubble of a manufacturing area of 20 square miles would therefore require about 6,000 tons of bombs.
During a 90-day bombing campaign the key German cities would be smashed by 90,000 to 150,000 tons of bombs. In a six-month campaign, the bomb tonnage might reach 300,000 tons. This means that every one of the 31 key cities would receive 6-10,000 tons, or up to 20 times the total weight of bombs dropped on Birmingham. On special targets, this total can be doubled or trebled by postponing other targets or lengthening the campaign.