Why the Skua Only Carried a 500lb Bomb

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Its hard to say exactly but the USN had those long flight decks and fast carriers so they had considerable leeway for increased TO weight. However, I've run accross crew reports that indicate that performance was somewhat less than the SAC data indicates.
 
Skua 8,215 pounds with 500 pound bomb, take off and clear a 50 foot obstacle, 670 yards, so 2,010 feet, at 8,625 pounds (full fuel) 770 yards or 2,310 feet. Martlet I 6,835 pounds 520 yards, so 1,560 feet.

F4F-3 7,556 pounds, take off from land, normal power, in feet, breeze 0 knots 500 feet, 15 knots 350 feet, 25 knots 234 feet.
SBD-3/4 9,968 pounds, 500 pound bomb, as per F4F-3, 1,100, 720 and 500 feet, a 1,000 pound bomb added around 100 feet.

So the SBD took about twice the distance as the F4F, the Skua around 50% more then the Martlet I. The Skua was 26% heavier than the Martlet I, the SBD-3/4 32% heavier than the F4F-3.

I am sure someone has the take off over 50 feet data for the F4F and maybe SBD.
 
Hi
Strangely despite this statement the RAF went to war with 250 lb and 500 lb SAP bombs plus the 2000 lb AP bomb, first used, unsuccessfully, on 7 May 1940 against a German cruiser by a Bristol Beaufort. The aircraft specifications pre-war; 10/36 - which became the Beaufort and Botha specified they should be able to carry one 2,000 lb. AP bomb. B12/36 - which were the Stirling and the Supermarine bomber were specified to be able to carry 7 x 2,000 lb AP bombs, 3 of them in the fuselage bay and two in wing cells in each wing between fuselage and inner engine. B13/36, which became the Manchester and Halifax were to be able to carry 4 x 2,000 lb AP. 29/36 - specification for the manufacture of the Wellington, were to carry 2 x 2,000 lb AP bombs, as was the Hampden under specification 30/36. The Whitley also could carry it. (info from 'The British Aircraft Specification File' Air-Britain and 'RAF Bomber Command and its aircraft 1936-1940' by Goulding & Moyes).
Extract about weapon from 'Bombs Gone' by MacBean and Hogben:

Not the most successful of bombs, less than 10,000 evidently dropped according to the authors, it had a sleek heavy-forged steel case with only 166 lb of explosive (a problem with AP bombs was that the skin had to be thick enough not to break up when hitting thick armour plate), it also had to be dropped from a good height to achieve penetration . There was also a problem with its No. 37 fuse which caused 'blinds' (this was replaced in early 1944 in the Mk. IV but there was a lack of suitable targets). Fuse problems were not unknown in any air force, for example the US 8th Air Force had an Intelligence report on the December 1942 Lille raid that indicated that 30% of the bombs that were dropped were duds. This was due to effects of damp and the freezing of the fuses, methods were tried to reduce this but problems persisted, so British fuses were adopted until newer fuses could be introduced.

Mike
 
These links have been posted before by myself and others - they add a bit more explanation in terms the thinking of the Air Ministry/RAF/FAA relative to AP bomb development and procurement in the interwar period

450 lb AP bomb "http://www.wwiiequipment.com/index....armour-piercing-bomb&catid=43:bombs&Itemid=60"
1500 lb AP bomb "http://www.wwiiequipment.com/index....armour-piercing-bomb&catid=43:bombs&Itemid=60"

There were several hundred of he 450 lb AP bomb procured, and it is listed as such in some of the pre- and early-war British ordinance manuals. It is not the 500 lb SAP, which was a completely different bomb. It is, however, sometimes referenced in various literature as a 500 lb AP bomb.


re the 2000 lb AP bomb - from MikeMeech's post above:

"Discussions about modifying the [1500 lb AP] bomb to have a smaller diameter or whether a heavier bomb would have to be used were carried out and in January 1928 it was realised that the original requirement would never be met by a 1500lb bomb at low velocities and a heavier bomb would be necessary."

After the decision to end development of the 1500 lb AP in 1931, the Air Ministry/RAF developed the "heavier bomb" in the form of the 2000 lb AP bomb mentioned by MikeMeech in his post just above. This was basically a lengthened version of the 1500 lb AP bomb. The forebody followed the 1500 lb design, with the same maximum Ø13.5" - and the body was lengthened to increase the effective weight to 2000 lb.

Unfortunately for the FAA, they had no aircraft able to carry the 2000 lb AP until the Barracuda entered service in 1943. Note that the Barracuda was tested by A&AEE in mid-1943, with the 2000 lb AP bomb carried on centerline. I have not been able to find any details on the tests.
 
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Mason's The Secret Years states this about testing a 2000lb bomb on a Barracuda II:

"P9816 from June 1943 investigated range and the effect of torpedo (810 miles maximum 650 miles practical) and alternatively six 250 Ib bombs (780 and 625 miles). ASV radar aerials cost 5% in range, and flying with hot air to the engine reduced range by 11%. Range on P9867 with single bombs up to 2,000 Ib on centreline was similar to the torpedo figure."

Post war the 2000lb bomb was used by Barracudas in testing against the deck armour of HMS Nelson, prior to her being scrapped. Apparently the bombs had to be released above 4000ft to have a reasonable chance of penetrating Nelson's 6in deck armour (See RA Burt British Battleships 1919-45)
 
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A quick look says the British kept making 250 pound SAP until mid 1943, 500 pound SAP until end 1943, 2,000 pound AP until mid 1944.

Bomber Command dropped 2,290x2000 pound AP, not sure who else dropped them in large numbers. On 1/2 July 1940 only 1x2000 pound AP bomb was dropped in the raid, it was the first use of the bomb by Bomber Command. Bomber Command night of 26/27 February 1942, the raid that badly damaged Gneisenau, did not use AP, dropping 4x4000 pound HC, 41x1000 pound GP, 51x500 pound SAP, 79x500 pound GP, 8x250 pound GP, the hit was reported to be a 4,000 pound bomb.

When the USSBS went out and counted the bombs dropped on several German oil targets they found overall around 14% failed to explode.

Seems badly assembled bombs would not drop straight or would lose their tails, some Germans actually asked the US investigators post war what experiments were the allies doing with tail less bombs, which gives an idea of how often it happened. Add bombs not fitted with fuses, or not properly filled with explosives or where the safety pins were left in before faulty fuses.

The USSBS investigators were shown dumps of allied UXBs. The RAF dud rate was higher than the USAAF one in the sample.
 
The other part of that story of Operation Bronte was that the initial dropping height was supposed to be 8,000ft. After 39 straight misses (against a stationary target) the dropping height was reduced to 6,500ft and a hit obtained with the 42nd drop (from an actual height of 5,900ft). At that point the trial was discontinued as the "exploding charge appeared to be too powerful" and only 60 bombs had been prepared for the trial. The charge had been reduced to 23.25lb of TNT, presumably to not cause too much damage and allow an assessment of the armour penetration capabilities of the bomb.

This shows that the bigger the AP bomb the higher it needs to be dropped to be effective and the harder it is to hit the target in the first place.
 
EwenS said:
This shows that the bigger the AP bomb the higher it needs to be dropped to be effective and the harder it is to hit the target in the first place.
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I am not sure that is quite right in regards to the first part. It is certainly true about getting the hit in the first place with increased height.

Any particular AP bomb will get increased penetration with increased height of drop up until terminal veleocity* is reached.
*terminal veleocity=force of gravity accelerating the bomb equals the drag of the bomb though the air. Bomb may actually slow down a bit near sea level.

Penetration is pretty much governed by the size of the bomb (diameter = hole it is trying to make) and the weight of the bomb per unit of surface area times the impact veleocity squared ( I think I have that right).
US 1600lb AP bomb would go through more armor at the same height than the 1000lb AP bomb. Or to say it another way the 1000lb bomb needed to be dropped from several thousand feet higher to get the same penetration. The 1600lb does need to be dropped from a higher altitude to reach it's full potential.
And since you only needed either one for attacking battleships the target selection is a bit limited. The 1000lb AP bomb would certainly defeat any cruiser or Carrier.

The British 2000lb AP was actually a smidgeon smaller in diameter than the US 1600lb bomb and with it's extra 400lb of weight it should have penetrated better. This assumes equal quality steel, heat treatment, actual shape of nose and that the extra length of the bomb body doesn't make the bomb break up by yawing during penetration (and other stuff I may have left out).
 
Hi
Wasn't the US 1600 lb AP AN Mk.1 a rather later design than the British pre-war 2000 lb AP bomb, so presumably more refined from experience, as the former appears to only have entered service in May 1942? I think there was an earlier US 1400 lb AP bomb (M63) with 70 lb of HE inside, declared obsolete in 1943. Also declared obsolete in 1943 was the M52 1000 lb AP bomb.
What were the bombs actually used in the 1942 Pacific battles by the USN? For example how many 1000 lb bombs at Midway and were they AP or GP?

Mike
 
I posted this up a few weeks ago about US armour piercing bombs on another thread.


"I can't trace a USN AP or SAP bomb from the pre-war period. This may explain why (from Dictionary of American Naval Air Squadrons Vol 2 Appendix 2:-

"Effective armor-piercing (AP) bombs were not developed
by the U.S. Navy between the wars because
near misses did not produce pressure-wave damage to
surface ships equal to similar weight light-case bombs."


To be effective an AP bomb needed dropped from height. That reduced the chances of a hit. Hence the idea that a large HE explosion from a near miss was a better solution to attacking any warship.


The US Army had a series of AP weapons ranging from 600-1,400lb converted from seacoast artillery shells. Their AP M-52 1,000lb bomb was produced between March 1942 and June 1943. Their M63 1,400lb weapon was produced Oct 1942 to Jan 1943.


Production of the AP Mk.1 1,600lb didn't start until Jan 1942 and AP Mk.33 1,000lb for the Navy didn't begin until Oct 1942 with Army production beginning in March 1943.
Pre-WW2 the USN had a 1,000lb Mk.13 GP bomb."
 
MikeMeech said:
Wasn't the US 1600 lb AP AN Mk.1 a rather later design than the British pre-war 2000 lb AP bomb, so presumably more refined from experience, as the former appears to only have entered service in May 1942?
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I don't think the US had much in the way of practical experience except range tests by the time the 1600lb bombs approved and put into production which had to a number of months before it was issued for service. The British may have sent some notes over but I am not sure what help they were. The Americans and British did not see eye to eye about types of steel or manufacturing techniques of artillery shells. British observations may have been useful but details of how to build them may not have been.
MikeMeech said:
I think there was an earlier US 1400 lb AP bomb (M63) with 70 lb of HE inside, declared obsolete in 1943. Also declared obsolete in 1943 was the M52 1000 lb AP bomb.
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The US Navy had a series of AP bombs in 1941, I don't know how much earlier. Information is from 'Campbell' Naval Weapons of WW II.
M52................1000lbs
M60..................900lbs
M61..................800lbs
M62..................600lbs
M63................1400lbs
Not sure if they were shared with the army.
They were replaced from May 1942 on by the 1600lb bomb. Since I don't think they ever hit a Japanese battleship with one there was no combat experience to go on either way.
Burster was supposed to about 5% (or no less than that amount) of ammonium picrate.
MikeMeech said:
What were the bombs actually used in the 1942 Pacific battles by the USN? For example how many 1000 lb bombs at Midway and were they AP or GP?
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Information from Campbell is pretty sketchy as to dates or details about the SAP and GP bombs.

From Friedman there are some lists, I am abbreviating them.
ship..............Lexington 1936...................Ranger 1934....................Ranger 1941....................CV 9 Jan 1940...............Essex 1942
100lb........................894...................................749.......................................600...........................................522...............................504.............
500lb........................391...................................174.......................................515...........................................450...............................296.............
1000lbGP...............240...................................130.......................................177...........................................148...............................146.............
1000lbSAP...............................................................................................................................................................................................129.............
1000lbAP..................................................................................................................................................................................................110.............
1600lbAP....................................................................................................................................................................................................19............
2000lbAP....................................................................................................................................................................................................19............
Torpedoes..............36..........................................................................................................................................36................................36............

The early carrier list (all but the Essex 1942) did not break down the bombs as to what type. Later lists did. The CV 9 1940 lest was the planned full war time load, there was a lower number listed for 1939 (peace time?). I did not list 30lb bombs, depth charges or incendiary bombs.
 
Contrary to what you extracted from Campbell, I took my information from the "United States Bombs and Fuzes Pyrotechnics" Manual dated 1 Sept 1945.

Section I Part II - US Army 'M' Series bombs lists the M52-63 weapons (page 12 of the document onwards). Converted from "seacoast artillery shells" of 10-14" diameter. Coastal defence guns were a US Army responsibility not a USN one, although a few of the guns had originally been built for the USN.

Section I Part III - US Navy 'MK' Series Bombs lists no AP weapons.

Section I Part IV - US Army-Navy 'AN' Series Bombs lists the AP 1,000lb Mk 33 & 1,600lb Mk 1
 

Attachments

  • USNBD - US Bombs and Fuzes (Sept 1945).pdf
    70.1 MB · Views: 31
Two things are for certain:
The Skua had perfect provision for a more powerful engine, R-1830 or even an R-1820. But the brits were determined to not mix their native airframes with US motors.
Even in the most dire of circumstances, the aeronautical 'socialism' held sway.
The Bristol Perseus was unreliable and a dead end for every aircraft it was motored with, so without more HP there could be no more development.
An American radial would of allowed for a larger bomb, the Skua is larger than generally thought.

Also, in lieu of going for a scout/dive bomber with maneuverability, the FAA never really bought into dive bombing. Of course Taranto had a lot to do with that, but that was never repeated, was it?
Dive bombers continued to be effective in the Pacific. The FAA moved away from the scout/dive bomber and went for torpedo bomber/with shallow dive capability (which means not a true vertical dive bomber, hence less accuracy). The Fulmar and Barracuda essentially took the FAA out of serious combined ops for the rest of the war. Bad strategic and doctrinal thinking. How lucky they were to get away with it.
 

Could the engines you propose actually be fitted to the Skua easily, considering mountings and spacings? I mean, where you drill the holes into the airframe, that sort of thing? Are you saying they could be dropped in? Or would changes need to be made on the factory floor?

Forgive what might seem to be ignorant questions.
 
Depends on how much work you want to do.
I seriously doubt they could be "dropped in" but since they lengthened the nose of the Skua by almost 2 ft to correct the CG after the 1st one (maybe the 2nd?) there was an awful lot of empty space to handle changes/modifications.
With the small number built (190) setting up a modification center probably wasn't worth while. Problem is they didn't have a good successor or at least one that followed in sort of a straight line. The RN got good value for the money spent on the Skua, value for the Roc is not so good. Not getting into the Albacore as a dive bomber argument. And that leaves the Barracuda showing up around 2 years after the Skua goes out of service let alone out of production.

A MK III Skua (the MK I was the first two prototypes with Mercury engines) with Either the R-1820 or R-1830 would certainly have been interesting even if not much faster.
 
Thank you for the attachment.
It certainly looks like the Navy didn't use the Army AP bombs unless it was in such small numbers that they never renamed them (dropped them in tests?) . I certainly don't know how long the Army had the bombs. No idea if the navy "borrowed" any after Pearl Harbor.

However there was a statement earlier about the Navy not liking AP bombs because of the small bursting charge gave very little results from a near miss ( I am rephrasing this) so it was pretty much hit or miss. Navy preferred the large burster of the GP bomb/s that would cause damage from near missed.

The 5% or under bursters in the Army AP bombs certainly go along with that.
Navy could have had their own test bombs that mirrored the Army ones and were never given a standard designation?
 
R-1820 is closer fit - within 1" on both length and diameter to Perseus. And only about 100lbs (10%) heavier. 10% more power than Perseus really wouldn't suddenly make it speed demon, but wouldn't hurt.

Fairchild Aircraft modified a Bolingbroke (Bristol Blenheim build in Canada) to house R-1820s, so there are kissing cousins to what is suggested.
 
keithwwalker said:
But the brits were determined to not mix their native airframes with US motors. Even in the most dire of circumstances, the aeronautical 'socialism' held sway.
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Socialism would require the government to own the engine factory. Defence Autarky tends to be policy and fashionable. Skua production was from October 1938 to January 1940, before things became dire.

The US Neutrality Act meant anybody using US equipment ran a big risk that going to war would see supply of the equipment and spare parts cut off. If that was overcome then came generating US dollars while fighting a war to pay for the equipment. And being able to continually obtain the relevant export licenses.

The US and UK aviation industries developed in parallel, which meant lots of different solutions to the same problems and lots of different ideas on standards. Australian experience in changing Taurus to Twin Wasp engines in the Beaufort -

"Redesign of engine nacelle, cowl and cowling panels, engine controls, propeller controls, cowl gill controls and engine bulkhead, and the repositioning of the major accessories and fittings."

"Electric, hydraulic and pneumatic controls had to be realigned. In fact, practically every part of the plane's control systems had to be altered to enable twin row wasp engines to be used in the machine."

Changing engines could be done as the many wartime examples showed and some would be easier than others, it was more than weights and dimensions.
 
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