Napalm delivery

[davebender]

Napalm

In Vietnam, the most frequently used container of napalm held about 130 gallons of gasoline with a solution of six percent napalm added. When dropped from "hedge-hopping" — those flying at an altitude of about 100 feet — the device was able to cover a surface with flames 270 feet long and 75 feet wide.

Drop Ordnance - Luftwaffe Resource Center - A Warbirds Resource Group Site

On impact, the fuze fires the gaine and the picric burster pellats, breaking the case and scattering the filling over a radius of about 70 yards. The filling ignites spontaneously, burning with a great deal of smoke.

I assume Germany adopted this delivery method because it was compatible with their dive bombers. USA didn't dive bomb to any great extent which probably influenced decision to adopt low altitude skip bomb system.

Has anyone else employed the WWII German method for aircraft delivered flame fuel weapons?

 

[tyrodtom]

I can't say that I saw ever variety of munitions dropped by the USAF, but I've never seen a 130 gal napalm bomb.
I helped make plenty of 100 gal BLU-37, and 67 gal BLU-23 bombs and even a smaller 33 gal. version, but nothing bigger than 100 gal.
There was versions in all sizes made by Dupont, and also the hand assembled version like my crew made, sort of like assembling a small aluminum airplane.
The pilots at NKP preferred the napalm made by us to Dupont's version.

I would think the Luftwaffe's version of firebomb would be a great deal more expensive to make, and more dangerous to store. A thin cased munition filled with a spontaneously combustible liquid would require some very careful ground handling, and storage.

 

[nuuumannn]

USA didn't dive bomb to any great extent

There are probably a few SBD squadrons that might disagree with this.

 

[swampyankee]

There are probably a few SBD squadrons that might disagree with this.

And maybe a few IJN sailors. The US didn't dive bomb that much in Europe, probably as they had found that specialist dive bombing aircraft were too vulnerable to fighters. Of course, sometime in 1945, that probably stopped being a concern, but the USAAF found no need to reform specialized dive bomber units. Why bother? The Germans were beaten, but their leadership just hadn't figured it out yet.

 

[stona]

The RAF hardly used it in Europe. Group Captain Gillam remembers:

The 12th April attack was on German troops near Arnhem and was less than a resounding technical success, though it severely shook their morale and they surrendered to ground forces shortly afterwards.

There is a piece of film floating around somewhere, taken at Boscombe Down, showing a Typhoon or Tempest dropping napalm from very low level.

Cheers

Steve

 

[davebender]

SBDs spent relatively little time conducting CAS. Hence napalm and other CAS type weapons weren't a major consideration.

Post WWII Skyraider is an entirely different matter. CAS was probably the most common mission and the aircraft could bomb at steep angles. There's no reason it couldn't employ an American version of German FLAM C250 bomb.

 

[Airframes]

Steve, Group Captain Gillam is not quite correct. Napalm was used by the Mosquitos of 100 and 2 Groups, on 'Firebash' operations, mainly against enemy airfields (I'd need to check this last point.). I believe 2 Group Mitchells also carried out 'Firebash' ops, and the napalm containers appeared to be the 108 gal, British made, 'paper' drop tanks, as used by the USAAF.

 

[tyrodtom]

I see no advantage to the Flam C250 bomb, and several disadvantages.

The figures for the flame affected area of the US munitions was probably just as accurate what they stated the average napalm bomb size was.
The flame affected area shape was tied to the angle of delivery, the steeper the delivery angle, the less oblong the burn area.
That site is wrong in stating that the method of delivery was skip bombing, method of delivery depended on terrain, enemy opposition, and what the pilot wanted to accomplish with the firebomb.

 

[Shortround6]

And maybe a few IJN sailors. The US didn't dive bomb that much in Europe, probably as they had found that specialist dive bombing aircraft were too vulnerable to fighters. Of course, sometime in 1945, that probably stopped being a concern, but the USAAF found no need to reform specialized dive bomber units. Why bother? The Germans were beaten, but their leadership just hadn't figured it out yet.

Dive bombers are also rather vulnerable to things like multiple .50 cal/20mm mounts and 37-40mm AA guns. In 1939-41 when many armies depended on troops firing bolt action rifles and a few LMGs for a large part of their AA defense dive bombers had things pretty much their own way. A British Army infantry Division had 4 single mounted Bren guns on trucks in each battalion for AA work in 1939-40. No heavier AA was supplied at division level or below. By 1942-42 the truck mounted Brens were gone and an AA regiment of 48 towed 40mm guns was being used in each division. In 1944 for Normandy the regiment was expanded to 54 40mm guns and reinforced by 24 truck mounted 20mm guns, lack of German air attacks saw the 20mm batteries disbanded.

The Dive needed for the dive bombers accuracy and the pull-out gave too much warning and time to track and fire for the AA guns.

 

[stona]

Steve, Group Captain Gillam is not quite correct. Napalm was used by the Mosquitos of 100 and 2 Groups, on 'Firebash' operations, mainly against enemy airfields (I'd need to check this last point.). I believe 2 Group Mitchells also carried out 'Firebash' ops, and the napalm containers appeared to be the 108 gal, British made, 'paper' drop tanks, as used by the USAAF.

I think Gillam was referring specifically to fighter-bomber operations. The quote was a little misleading out of context.
2nd TAF stuck with rockets and conventional bombs, whereas their American colleagues in NW Europe did adopt napalm on a fairly large scale and didn't use rockets to any great extent.

I'm guessing those Mosquito operations came when the 2 Group was under Fighter Command or the Allied Expeditionary Air Force. Surely 100 Group aircraft weren't bombing airfields.

Cheers

Steve

 

[Airframes]

Ah, I understand Steve.
Yes, late in the war, the 100 Group Mossies undertook a number of Intruder and 'Firebash' ops, against airfields. I'd need to check the latter, as this may have been the Mossies and Mitchells of 2 Group, under 2 TAF command. It's all recounted in Bowman's 'Mosquito Panick'.

 

[drgondog]

8th AF FC used primarily 108 gallon fuel tanks with special igniters for Napalm dispenser..

 

[swampyankee]

Dive bombers are also rather vulnerable to things like multiple .50 cal/20mm mounts and 37-40mm AA guns. In 1939-41 when many armies depended on troops firing bolt action rifles and a few LMGs for a large part of their AA defense dive bombers had things pretty much their own way. A British Army infantry Division had 4 single mounted Bren guns on trucks in each battalion for AA work in 1939-40. No heavier AA was supplied at division level or below. By 1942-42 the truck mounted Brens were gone and an AA regiment of 48 towed 40mm guns was being used in each division. In 1944 for Normandy the regiment was expanded to 54 40mm guns and reinforced by 24 truck mounted 20mm guns, lack of German air attacks saw the 20mm batteries disbanded.

The Dive needed for the dive bombers accuracy and the pull-out gave too much warning and time to track and fire for the AA guns.

The density of AAA on warships was probably higher than that in almost any ground formation, and dive bombers were used against numerous warships with quite good effect. Even outside of the Pacific, the Germans and British lost significant numbers of warships to divebombing attacks. Obviously, in the Pacific the IJN lost many major units to USN divebombers.

 

[gjs238]

A-36 Apache performed well, no?

 

[Shortround6]

Loosing some aircraft in return for sinking one or more ships, especially large ships is a good trade. Loosing some aircraft for a group of trucks is not a good trade. How many trucks is a dive bomber worth?
A tank is worth (costs) about 10 towed guns.

taking out a bridge at a critical point/time may be worth it. As general "fire support" dive bombers are an expensive way to deliver HE payloads. The Japanese army never got close to the level of AA equipment the western nations did and dive bombers remained a valuable tool in the Asian theater.

 

[davebender]

More vulnerable then a level bomber flying @ 100 meters? I have my doubts.

Where's that Croatian light AA gunner when we need an expert opinion?

 

[swampyankee]

A-36 Apache performed well, no?

After dropping its bombload, the A-36 could probably fight anything the Germans had on a near-equal footing. It was, after all, a P-51 in disguise.

 

[Shortround6]

Lets see, Dive bombers approach target area at what altitude? 6,000-12,000ft?

At what speed?

Dive bombers either climb to or cruise at 8,000-12,000 ft to begin dives. (longer dive gives more time to aim and improves accuracy)

Dive bomber executes a straight (no jink or dodge flight path) until the bomb release altitude at which point it does a 5-6"G" pull out with NO turn until the plane regains near horizontal flight several thousand feet above ground level.

At which point our heroes can begin evasive action.

Yep, I can see how the Dive bombers are in little danger from AA guns as the gunners are all busy putting down their tea and biscuits where they won't spill/get stepped on and are ambling over to the guns.

From wiki on the Stuka:

" The automatic pull-out was not liked by all pilots. Helmut Mahlke later said that he and his unit disconnected the system because it allowed the enemy to predict the Ju 87s recovery pattern and height, making it easier for ground defences to hit an aircraft."

 

[R Leonard]

SBDs spent relatively little time conducting CAS.

If one were to take the time to look up the data one might be able to find that carrier and land based SBD's flew some 49,792 combat sorties during the war. Of this total 1,422 were against warships, 2,045 against merchant vessels and another 98 for which the ship time was not sufficiently identified for classification. This totals to 3,565 action sorties against things floating on the water. The remaining 46,227 sorties were against land targets, breaking down as:
Airfields - 7,133
Land transportation targets - 1,385
Harbor facilities - 521
Military Targets including CAS - 36,413
Unclassified land targets - 775

So, only 7.2% of SBD attacks were made on vessels, warships, merchants, what-have-you. The other 92.8% were against land targets. In the course of these action sorties against land SBDs delivered 21,621 tons of bombs (94.2% of the SBD total tonnage delivered), 6,991,000 rounds of ammunition (97.0% of total SBD ammunition expended) and 144 rockets (62.1% of total SBD carried rockets expended) . . . all against land targets.

By 1944 land based SBDs, almost exclusively operated by Marine VMSB squadrons devoted 95.8% of their effort against land targets - 18,878 action sorties out of a total of 19,706. Only 828 action sorties were against any form of floating target. Action sorties against land targets by land-based SBDs during 1944 were broken down as:
Grounded aircraft - 9
Airfield runways - 2,169
Defense installations/gun positions - 9,405
Personnel and bivouac areas - 2,066
Buildings storage areas - 4,446
Docks waterfront - 120
Roads, bridges vehicles - 523
Other unspecified land targets - 140

So, just for the one year of 1944 it is easy to calculate that the action sorties against land targets by land-based SBDs made of 40.8% of the entire SBD effort against land targets for the war and 37.9% of the entire SBD effort against all targets for the war.

By 1945 US piloted SBDs were used exclusively by the VMSB squadrons operating in the Philippines in CAS of US Army operations, the last SBDs were withdrawn from combat operations in mid-July 1945. During those last 7½ months of operations the Marine SBDs flew 17,471 action sorties against land targets, delivering 8,125 tons of bombs and expending 2,940,000 rounds of ammunition. Adding the 1944 and 1945 land-based action sorties together brings a total of 36,349 or 78.6% of SBD action sorties against land targets for the entire war and 73.0% of all SBD action sorties of any kind for the entire war.

Seems that the operating data indicates that the SBD might have spent more than just a little effort on land targets and in a CAS mode.

 

[tomo pauk]

Great stuff.