500 Pound Bomb vs 1000 Pound Bomb

[Checkertail20]

As you can tell by my user name I have an interest in the 325th Fighter Group best known as the Checkertail Clan. On studying them I came across a story where they began experimenting with using 1000 pound bombs and was successful. From what I've read they were the only fighter group in the 15th Air Force to accomplish this but was this a good idea. I understand the bigger the bomb the more damage but with the extra weight the less range a plane would have and not only that how much practice would be needed to adjust to dropping heavier bombs accurately on targets. I am no expert on air war tactics but was this really practical or should they have just stayed with the 500 pound bombs?

 

[Alan Stevens]

As you can tell by my user name I have an interest in the 325th Fighter Group best known as the Checkertail Clan. On studying them I came across a story where they began experimenting with using 1000 pound bombs and was successful. From what I've read they were the only fighter group in the 15th Air Force to accomplish this but was this a good idea. I understand the bigger the bomb the more damage but with the extra weight the less range a plane would have and not only that how much practice would be needed to adjust to dropping heavier bombs accurately on targets. I am no expert on air war tactics but was this really practical or should they have just stayed with the 500 pound bombs?

Both of them / either of them wreaked tremendous damage to the Kido Butai at Midway.

 

[Geoffrey Sinclair]

325th Fighter Group to 12th Air Force North Africa 28 February 1943 flying P-40, first mission 17 April, transitioned to P-47 (as of 31 October 70 P-47D, 1 P-40F, 1 P-40L), to 15th Air Force first mission 14 December 1943, last P-47 operation 24 May, 1st P-51 operation 27 May 1944.

According to the 15th Air Force report its P-47 Units dropped none and its P-51 units a total of 1 ton of bombs, by the 52nd Fighter Group on 29 April 1945, a tactical target in the Udine area. It actually was the last fighter bomber operation done by 15th Air Force units. The 15th Air Force P-38 units are credited with dropping 3,044 tons of bombs, including 1,000 pound HE.

325th Fighter Group record with 15th Air Force, 9,712 sorties, aircraft losses 21 flak, 11 to enemy aircraft, 60 other/unknown plus 26 non combat losses, claimed 262-21-47 enemy aircraft in the air flying P-51. Flying P-47 3,917 effective sorties, combat losses 41, 2 flak, 14 enemy aircraft, 25 other/unknown, air to air claims 150-25-22. All the above if I have correctly read the report about the P-47/51 split.

 

[33k in the air]

From what I've read they were the only fighter group in the 15th Air Force to accomplish this but was this a good idea. I understand the bigger the bomb the more damage but with the extra weight the less range a plane would have and not only that how much practice would be needed to adjust to dropping heavier bombs accurately on targets.

These combat radius figures are for the ETO, but they should prove illustrative. From the publication Tactics and Techniques Developed by the United States Tactical Air Commands in the ETO the combat radius at 10,000 feet. Note that the distance covered in the climb is included in the radius.

P-38L
290 miles = no external stores
260 miles = 2 x 500-lb bombs
250 miles = 2 x 1,000-lb bombs
400 miles = 1 x 1,000-lb bomb and 1 x 165-gallon drop tank

P-47D-25+
280 miles = no external stores
260 miles = 2 x 500-lb bombs
360 miles = 2 x 500-lb bombs and 1 x 108-gallon drop tank
230 miles = 2 x 1,000-lb bombs

P-51B/C/D
350 miles = no external stores
325 miles = 2 x 500-lb bombs

 

[33k in the air]

I understand the bigger the bomb the more damage but with the extra weight the less range a plane would have and not only that how much practice would be needed to adjust to dropping heavier bombs accurately on targets. I am no expert on air war tactics but was this really practical or should they have just stayed with the 500 pound bombs?

In regards to 1,000-lb versus 500-lb, the latter was by far the most commonly used HE bomb by the USAAF during the war. This was likely a reflection of bomb production priorities in the U.S. From the publication Official Munitions Production of the United States by Months, July 1, 1940 - August 31, 1945:

High Explosive Bombs

  500-lb  7,532,287  44.2%
  100-lb  4,043,000  23.7%
  250-lb  2,351,000  13.8%
1,000-lb  2,079,743  12.2%
  150-lb    450,000   2.6%
  300-lb    355,000   2.1%
2,000-lb    215,777   1.3%
4,000-lb*     6,225   0.04%

*In addition 38,805 bombs of the
 4,000-lb HC Mk V type were built
 for the British

  500-lb: 97.0% GP,  3.0% SAP
1,000-lb: 80.8% GP, 19.2% SAP
2,000-lb: 98.7% GP,  1.3% SAP

Only 1 in 8 high explosive bombs built were of the 1,000-lb class, and of those, nearly 20% were the semi-armor piercing type, a kind of limited use in Tactical operations. Reviews of 9th Air Force missions concluded that the most effective bombs against enemy forces were the 500-lb GP, the 260-lb fragmentation bomb, and the 540-lb fragmentation cluster (which contained 6 x 90-lb fragmentation bombs).

 

[Checkertail20]

Thanks for all the information.

 

[Greyman]

... was this a good idea ...

From ORS: REPORT ON BOMBING ATTACKS ON THE SAVIO RIVER BRIDGES. dated 15 Nov. 1944

As between 500 lb. and 1000 lb bombs there is no significant difference in the number of hits claimed (5.5) per hundred bombs dropped. As regards aircraft, higher claims were made by Spitfires and Thunderbolts, and the relative lack of success of these aircraft can be put down to their use of 500 lb. bombs. (Kittyhawks and Mustangs are the other two, these able to use 1x and 2x 1000 pounders, respectively)

...

From the few cases where photo cover gives an unequivocal assessment of damage it appears that the 500 lb. bomb is a relatively ineffective weapon for the destruction of heavy masonry bridges.

The number of 500 lb. bombs dropped on permanent road bridges is nearly twice as great as the number of 1000 lb. bombs dropped on these targets (628 as against 322), but only one bridge is known to have been destroyed by the former, as against five by the latter. Moreover, the only bridge definitely destroyed by a 500 lb. bomb had previously been damaged by a 1000 lb. bomb.

 

[alsaad]

 

[alsaad]

Here is a snap from the US publication Terminal Ballistics that shows destructive effect of the bombs of various sizes. Disregard writings in Bosnian as I only had in hand my lecture on the aircraft bombs and not source itself. 1000 lbs bombs were used on Mustangs P-51D by No. 249. and No. 213. squadron RAF.