Best bombs against Oil and Industrial Targets

[wuzak]

Discussion over on the Mosquito vs B-17 thread frequently comes back to what bombs are the best choice for certain targets, particularly oil refineries, synthetic oil plants and industrial targets in general.

Historically, it would seem that the USAAF preferred a large number of small bombs on oil targets, in the order of 100lb to 500lb, in order that some bombs may hit something vital. The plus side is that a large formation could carpet bomb the target and score a lot of these small hits.

The RAF, on the other hand, preferred the bigger bombs - 500lb and up, GP (MC) and HC type bombs. Late in the war they even tossed a few 12,000lb Tallboys at an oil facility. The advantage here is that when things are hit, or even near misses, extensive damage is caused. The downside is that the bomb drop has to be reasonably accurate. The bomb load would consist of a 4,000lb HC and several 500lb or 1,000lb MCs, or incendiaries.

For industrial targets/factories, the USAAF did use the bigger bombs, typically the 500lb GP, 1,000lb GP and 2,000lb GP bombs. The thinking must be that industrial targets require more explosive power to cause significant damage to plant and equipment.

The RAF used a similar load to the one for the oil targets.

Which is the better option - a lot of small bombs or fewer bombs with bigger bangs?

Do Armour piercing and semi armour piercing bombs, with their lower charge-to-weight ratio have a place in attacking such targets?

Would incendiaries help much with the destruction, or are they better suited to city targets?

 

[EwenS]

I think it depends on the type of facility you are seeking to destroy.

I hadn't appreciated until recently when I watched a TV documentary, just how a synthetic oil plant like Politz, producing oil from coal, differed from a traditional refinery taking crude oil and cracking it to provide different oil based products.

A traditional oil refinery has a few critical pieces of plant like powerhouses and distillation towers. Cripple those and a refinery can be put out of action for at least a period of months. I'm more familiar with attempts to strike Sumatran refineries in the DEI by USAAF B-29s based in India and the FAA using Avengers. In both cases the main weapon was the 500lb bomb. But these raids were not on the scale of 8th AF raids on German oil targets and its amazing just how quickly production could be restored at least in part.

Oil Refineries and Storage Centers under IJA Control, Bob Hackett

Details of the modern oil refineries here, although it should be noted that today's range of products is far greater than that of WW2

Oil Refinery Process Units, Refinery Equipment List

PCC's oil refinery usually consists of processing units like CDU, VDU, NHT, DHT, SRR, FCC, SRU, and Isomerization unit etc.

www.peiyangchem.com

Note it consists of plenty of above ground steel pipe work.

Places like Politz were completely different due to the processes required to take the coal, grind it into powder and process it at high pressures and temperatures using the Fischer Tropsch process of coal liquefaction.

Coal liquefaction - Wikipedia

en.m.wikipedia.org

The result was a series of heavily constructed structures many of steel reinforced concrete. It was taking 5-6 tons of coal to produce 1 ton of oil. So the volumes and weights involved are far greater than in a traditional refinery. It also seems to have been a much more dangerous process, with large numbers of slave labourers succumbing to their working conditions in these plants. There are some photos of the buildings at Politz on this site.

Politz Synthetic Oil Plant

Remnants of Politz Synthetic Oil Plant

www.battlefieldsww2.com

Given those heavy structures the use of ground penetrating 12,000lb Tallboy bombs begins to make some sense. However, IIRC there was only one such raid against an oil facility - Politz itself on 21 Dec 1944.

You will find details of the various Lancaster bomb loads and their uses here.

Bomb Loads

Lancaster Archive

www.lancaster-archive.com

One of the problems encountered with using incendiaries was that while they would burn out buildings quite nicely once they had been opened up by blast bombs, like the 4,000lb Cookie, any machinery contained therein tended to suffer limited damage and could usually be fairly easily salvaged, relocated and put back into use. The heavier it was the more likely it would survive. So to destroy the machinery they had to use high explosive bombs and then the British preference seems to have been the 1,000lb weapon, probably due to its ability to create damage over a much wider area. Against a traditional oil refinery I think they would have been of limited use in starting fires only after all the steel pipe work had been broken up by high explosive.

 

[Thumpalumpacus]

Which is the better option - a lot of small bombs or fewer bombs with bigger bangs?

Do Armour piercing and semi armour piercing bombs, with their lower charge-to-weight ratio have a place in attacking such targets?

Would incendiaries help much with the destruction, or are they better suited to city targets?

As I said in that thread, I'd go with a mix of large HE and cluster bombs.

 

[33k in the air]

For industrial targets/factories, the USAAF did use the bigger bombs, typically the 500lb GP, 1,000lb GP and 2,000lb GP bombs. The thinking must be that industrial targets require more explosive power to cause significant damage to plant and equipment.

While heavier bombs were used in Europe, by far the most commonly dropped bomb by the USAAF in Europe was the 500 lb, which comprised 36.5% of the total dropped from 1943-45. The top ten by percentage of total dropped, with the actual number used in parentheses.

36.5% = 500 lb HE (3,089,916)
18.0% = 100 lb HE (1.50209)
12.5% = 250 lb HE (1,055,289)
09.5% = 100 lb incendiary (806,394)
08.9% = 120 lb fragmentation cluster (756,304)
06.7% = 1,000 lb HE (564,969)
03.2% = 440 lb incendiary cluster (267,023)
02.4% = 260 lb fragmentation (198,758)
00.6% = 2,000 lb HE (48,575)
00.4% = 500 lb incendiary (33,905)

The 100 lb HE, 120 lb frag cluster, and 260 lb frag bombs were mostly dropped by fighter-bombers rather than the heavy bombers.

 

[Greyman]

From the U.S. Strategic Bombing Survey, Oil Division, Final Report

Oil Division Final Report, Oil Division - Google Play

play.google.com

General Summary

Small Bombs Stopped Production, but Did It the Hard Way
The small bombs generally used against German oil-chemical targets were capable of creating breaks in vital utilities systems, thereby temporarily shutting off plant production, but only very rarely were small bombs able to destroy vital equipment. (During the oil offensive, the average size of all the 508,512 high-explosive bombs dropped on oil producing targets by the USAAF was 388 lb, and of the 263,942 dropped by the RAF, 660 lb. The average for both air forces was 480 lb.) Winning a war with small bombs requires a tremendous air force, but this is possibly the only choice open if visual sighting is not possible or if vital aiming points are not chosen.

Only Large Bombs Destroy Vital Process Equipment
Few large bombs were used against German oil-chemical plants, and most of these were dropped by the RAF. It is the unanimous conviction of all Oil Division observers that, under bombing conditions which permit sighting on a specific aiming point and with reasonable bombing accuracy, heavy bombs (2,000 to 4,000 lb., instantaneously fuzed) are several times as effective per ton as the lightweight bombs (500 lb. or less) used principally against German oil targets.

Incendiaries Were Seldom Used Effectively
Very few instances of appreciable production loss were caused by the small number of incendiaries used against German oil producing targets (only 6,541 tons out of a total of 196,052 tons). In most instances, incendiaries burned themselves out or were extinguished before spilled oil or other inflammable material had time to spread and become the focal point of a serious fire. It was the opinion of German plant managers, concurred in by all Oil Division observers, that incendiaries dropped after or set to ignite several minutes following high-explosive attacks, would have resulted in far more serious fire damage.

Recommendations:

Table 47 (see bottom of post) summarizes Oil Division findings regarding the ability of munitions of various sizes, variously fuzed, to damage plant equipment in the oil, chemical, and rubber industries.

It is the conviction of all Oil Division ordnance officers, fire damage appraisers, and design, construction, and maintenance engineers who have participated in plant surveys that, for the munitions available for use against Germany;

1. Instantaneously fuzed large bombs (2,000 to 4,000-lb) should be employed against all targets in these industries whenever bombing technique, under prevailing aiming conditions , can ensure dropping a reasonable percentage of bombs on vital aiming points.
   
   
2. Under conditions that reduce bombing accuracy (full instrument attack , the types of air borne radar available , and air conditions which frequently existed over Germany), 500- and 1,000-1b bombs should be used in what is really area attack. It is clear that such attacks shut down the German plants in these industries, but attacks had to be repeated frequently (every two to four weeks) because the type of damage caused was so readily repaired.
   
   
3. Actual findings on incendiaries are very limited since they were used so infrequently during the attacks studied, and those dropped normally were extinguished before spills of inflammable material had a chance to spread, become ignited by the incendiaries, and serve as focal points for serious fires. Survey personnel believe that incendiaries dropped several minutes after high-explosive attack, or equipped with delay elements good for, say five minutes, would be most effective in any attack on these industries.
   
   
4. Delayed action action anti-personnel bombs should be used in order to delay the fire fighting and in order to get maximum results from any fires started.
   
   
5. Immediate steps should be taken to ascertain the reasons for the excessive number of un exploded bombs and to correct whatever defects in bombs or techniques are revealed.
   

Mainly 100-lb bombs were used in the earlier attacks. Later the majority were 300-lb or 500-lb bombs and finally 1000-lb bombs. The heaviest damage during the attacks occurring toward the end of July were done by 1000-lb bombs and resulted in a prolonged shutdown of the plant. The management considers the guided English night attacks with heavy caliber bombs to be more dangerous than the American day attacks, especially when the flak is handicapped by low visibility.

- Major General Gerlach of the Staff of the Luftwaffe Anti-Aircraft Defense of Leuna, November, 1944

My Fuehrer,
Since 13 January 1945 a new series of heavy attacks on the oil industry has been introduced, which has already led to prolonged shutdown of the great hydrogenation plants of Poelitz, Leuna, Bruex, Bleckhammer, and Zeitz, in addition to the complete shutdown during the last quarter of 1944 of all Western plants, especially Scholven, Wesserling, Welheim, and Gelsenberg. The repair of the plants after each attack has become more difficult owing to the use or destruction of reserves of machines and equipment; in addition, repairs take a longer time. It must also be stated that the now frequent night attacks are more effective than the day raids as heavier bombs are being used and an extraordinary accuracy achieved; therefore, even if the repair and production during the first quarter of 1945 were to proceed undisturbed, the planned production, which during the final quarter of last year seemed possible, can no longer be achieved. Heil Hitler!

- Albert Speer Reichsminister for Armaments Production

 

[MikeMeech]

While heavier bombs were used in Europe, by far the most commonly dropped bomb by the USAAF in Europe was the 500 lb, which comprised 36.5% of the total dropped from 1943-45. The top ten by percentage of total dropped, with the actual number used in parentheses.

36.5% = 500 lb HE (3,089,916)
18.0% = 100 lb HE (1.50209)
12.5% = 250 lb HE (1,055,289)
09.5% = 100 lb incendiary (806,394)
08.9% = 120 lb fragmentation cluster (756,304)
06.7% = 1,000 lb HE (564,969)
03.2% = 440 lb incendiary cluster (267,023)
02.4% = 260 lb fragmentation (198,758)
00.6% = 2,000 lb HE (48,575)
00.4% = 500 lb incendiary (33,905)

The 100 lb HE, 120 lb frag cluster, and 260 lb frag bombs were mostly dropped by fighter-bombers rather than the heavy bombers.

Hi
The book 'Bombs Gone - The development and use of British air-dropped weapons from 1912 to the present day' by MacBean and Hogben, mentions (p.133) that Bomber Command despatched 389,809 sorties and dropped about 955,044 tons of bombs, made up of the following (p. 135):

Also it has an 'ID Chart' on p.136:

The British OH 'The Strategic Air Offensive Against Germany 1939-1945 - Volume IV Annexes & Appendices' has translations of many German documents including some relating to oil, one is from Speer to Bormann:

Others are from Speer to Hitler, like the following:

They may be of interest.

Mike

 

[33k in the air]

Hi
The book 'Bombs Gone - The development and use of British air-dropped weapons from 1912 to the present day' by MacBean and Hogben, mentions (p.133) that Bomber Command despatched 389,809 sorties and dropped about 955,044 tons of bombs, made up of the following (p. 135):

Do you have your own copy of that book? There is supposedly a copy of it in the reference library in my city of residence, but I haven't been able to go look at it myself yet.

 

[Milosh]

Do you have your own copy of that book? There is supposedly a copy of it in the reference library in my city of residence, but I haven't been able to go look at it myself yet.

Used for just under $18. Amazon product ASIN 1852600608
View: https://www.amazon.ca/dp/1852600608/

 

[MikeMeech]

Do you have your own copy of that book? There is supposedly a copy of it in the reference library in my city of residence, but I haven't been able to go look at it myself yet.

Hi
Yes it is my own copy, as is the other book mentioned in the post. I have built up quite an extensive library since the late 1960s onward.

Mike

 

[EwenS]

Many of the British Official Histories, including The Strategic Air Offensive Against Germany vol IV referred to above, are now available online here.

Second World War - FIBIwiki

wiki.fibis.org

There is many years worth of reading in there. The only question is where to start!

 

[Deleted member 68059]

Discussion over on the Mosquito vs B-17 thread frequently comes back to what bombs are the best choice for certain targets, particularly oil refineries, synthetic oil plants and industrial targets in general.

Historically, it would seem that the USAAF preferred a large number of small bombs on oil targets, in the order of 100lb to 500lb, in order that some bombs may hit something vital. The plus side is that a large formation could carpet bomb the target and score a lot of these small hits.

The RAF, on the other hand, preferred the bigger bombs - 500lb and up, GP (MC) and HC type bombs. Late in the war they even tossed a few 12,000lb Tallboys at an oil facility. The advantage here is that when things are hit, or even near misses, extensive damage is caused. The downside is that the bomb drop has to be reasonably accurate. The bomb load would consist of a 4,000lb HC and several 500lb or 1,000lb MCs, or incendiaries.

For industrial targets/factories, the USAAF did use the bigger bombs, typically the 500lb GP, 1,000lb GP and 2,000lb GP bombs. The thinking must be that industrial targets require more explosive power to cause significant damage to plant and equipment.

The RAF used a similar load to the one for the oil targets.

Which is the better option - a lot of small bombs or fewer bombs with bigger bangs?

Do Armour piercing and semi armour piercing bombs, with their lower charge-to-weight ratio have a place in attacking such targets?

Would incendiaries help much with the destruction, or are they better suited to city targets?

The 4000lb cookie was noted as being particularly effective, the big issue is that pipework and such was pretty easy to repair, but that stuff like high pressure pumps was what really put a facility permanently out of action, and small bombs just didnt do that very well.

 

[JDCAVE]

Greyman quotes Speer's letter to Hitler, Jan, 1945: "during the last quarter of 1944 of all Western plants, especially Scholven, Wesserling, Welheim, and Gelsenberg."

Dad was on the raid to Bottrop Welheim, Sept 27, 1944 and to Scholven Buer, Dec 29, 1944. The first target wasnt hit very hard due to cloud cover, although I have an Aiming Point photo by Slim Barlow.

The raid to Scholven in miserable weather was highly successful. It was an Oboe guided attack. Dad carried 1 x 4,000 lb cookie and 16 x 500 lb bombs.

Dad's 419 ORB entry:
KB721 "B" Up 1510 down 2128. Target SCHOLVEN with 1 x 4000 lb HC Tinatol [sic, "Trinatol?], 6 x 500lb MC TD.025 and 10x 500 lb GP TD.025. Primary through 10/10th cloud, tops 3/5000 ft. at 1903.6 from 17,000 ft. Target ident. By TI's and Gee. Bombed TI and flares. One big explosion seen in T/A. Good attack.

 

[Col Campbell]

Here are some bomb loads from my father's flight log of his B-17 missions against oil targets.

Nov. 25, 1944 – mission against synthetic oil plant in Merseburg. Carried 12 x 500-lb GP bombs.

Feb 6, 1945 – mission against synthetic oil plant in Chemnitz. Carried 6 x 500-lb bombs.

Feb 9, 1945 – mission against oil target in Chemnitz. Carried 10 x 500-lb bombs.

Mar 3, 1945 – mission against oil refinery in Edmison, Germany. Carried 12 x 500-lb bombs.

Mar 5, 1945 – mission against synthetic oil depot in Chemnitz, Germany. Carried 10 x 500-lb RDX bombs.

Mar 8, 1945 – mission against synthetic oil plant in Langendreer, Germany. Carried 14 x 500-lb bombs.

He flew another oil target mission on Mar 19, 1945 but there were no bomb load details indicated.

Jim

 

[JDCAVE]

Here are some bomb loads from my father's flight log of his B-17 missions against oil targets.

Nov. 25, 1944 – mission against synthetic oil plant in Merseburg. Carried 12 x 500-lb GP bombs.

Feb 6, 1945 – mission against synthetic oil plant in Chemnitz. Carried 6 x 500-lb bombs.

Feb 9, 1945 – mission against oil target in Chemnitz. Carried 10 x 500-lb bombs.

Mar 3, 1945 – mission against oil refinery in Edmison, Germany. Carried 12 x 500-lb bombs.

Mar 5, 1945 – mission against synthetic oil depot in Chemnitz, Germany. Carried 10 x 500-lb RDX bombs.

Mar 8, 1945 – mission against synthetic oil plant in Langendreer, Germany. Carried 14 x 500-lb bombs.

He flew another oil target mission on Mar 19, 1945 but there were no bomb load details indicated.

Jim

Very good Jim. Dad followed your fathers attack to Chemnitz on March 5, with an attack to Chemnitz that night, March 5/6. The weather over England was horrible and 7 aircraft crashed on takeoff, killing 40/49 aircrew.

Jim

 

[pbehn]

Greyman quotes Speed's letter to Hitler, Jan, 1945: "during the last quarter of 1944 of all Western plants, especially Scholven, Wesserling, Welheim, and Gelsenberg."

Dad was on the raid to Bottrop Welheim, Sept 27, 1944 and to Scholven Buer, Dec 29, 1944. The first target wasnt hit very hard due to cloud cover, although I have an Aiming Point photo by Slim Barlow.

The raid to Scholven in miserable weather was highly successful. It was an Oboe guided attack. Dad carried 1 x 4,000 lb cookie and 16 x 500 lb bombs.

Dad's 419 ORB entry:
KB721 "B" Up 1510 down 2128. Target SCHOLVEN with 1 x 4000 lb HC Tinatol [sic, "Trinatol?], 6 x 500lb MC TD.025 and 10x 500 lb GP TD.025. Primary through 10/10th cloud, tops 3/5000 ft. at 1903.6 from 17,000 ft. Target ident. By TI's and Gee. Bombed TI and flares. One big explosion seen in T/A. Good attack.

View attachment 649881

Interesting mention of "scarecrow".

 

[JDCAVE]

Interesting mention of "scarecrow".

Yes. Probably one of the 2 aircraft 419 aircraft shot down by flak.

 

[pbehn]

Yes. Probably one of the 2 aircraft 419 aircraft shot down by flak.

I thought it was just a rumour among crews not something officially reported.

 

[wuzak]

Feb 6, 1945 – mission against synthetic oil plant in Chemnitz. Carried 6 x 500-lb bombs.

Feb 9, 1945 – mission against oil target in Chemnitz. Carried 10 x 500-lb bombs.

Were they running short on bombs on the 6th?

 

[BiffF15]

Were they running short on bombs on the 6th?

I don't know the answer to your question but will throw a few things out. Having participated in the planning of a strike, there are a few things that could cause a difference in bomb loads. First, is friendly compression over the target (get as many of your aircraft over or through the target area as possible at the same time) in order to overwhelm air defenses or minimize the time required to maintain air superiority. Then working back from there you have to deconflict target run in from other groups (packages) that are attacking neighboring targets. To get to that stage of deconfliction one group may have to fly a longer (or much longer) route (also part of the deception as to the intended target) which requires more gas. More gas means less bomb load. Or the weatherman could be forecasting bad wx on the RTB which in turn would require more fuel for diversion or a lower arrival rate. Or they diverted to this target as the prime was weathered out, and as a result arrived over the target with a less than optimum load out.

Cheers,
Biff

 

[JDCAVE]

Were they running short on bombs on the 6th?

Possibly. There was a shortage of bombs. Dad took 4 x 250 lb gp bombs to Dresden and also on one or two other ops. These were next to useless. It turns out, and I'd have to find a reference, there was a shortage of different bomb types, possibly due in part to the growth of the USAAF 8th and their requirements. Dad carried US ANM bombs on several raids.

jim