I can understand these tests as tests for info, but this is actually what they may have had to ditch in, in the North Sea.B-17 Ditching. The low wing design probably assisted in increased crew safety, opposed to B-24 ditching characteristics.
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Out of the Big Three WW2 bombers (B-17, B-24, Lancaster), was the Flying Fortress the most redundant?
- Thread starter spicmart
- Start date
Howard Gibson
Staff Sergeant
Which German aircraft that saw lots of service in WWII had high aspect ratio wings?
My understanding is that the Fw-190, noted for its very high rate of roll, had short wings and large ailerons. High aspect ratio means long skinny wings. This means high moment of polar inertia, and ailerons a long way from the centre of mass.
- Thread starter
- #283
Though the wings are short, the aspect ratio is higher than in most or all Allied fighters.
Granted, the Ta 152H has a real high aspect ratio wing
ThomasP
Chief Master Sergeant
Various fighter aircraft wing aspect ratios
Fw 190____ 6.04
Ta 152_____8.88
Me 109E___5.97
Me 109F___6.14
D.520_____ 6.56
Hurricane__6.20
Spitfire____ 5.61
Fulmar____ 6.30
Whirlwind__8.10
P-38______ 8.24
P-39______ 5.43
P-40______ 5.90
P-47______ 5.60
P-51______ 5.88
F2A_______5.86
F4F_______5.55
F4U______ 5.35
F6F_______5.49
Fw 190____ 6.04
Ta 152_____8.88
Me 109E___5.97
Me 109F___6.14
D.520_____ 6.56
Hurricane__6.20
Spitfire____ 5.61
Fulmar____ 6.30
Whirlwind__8.10
P-38______ 8.24
P-39______ 5.43
P-40______ 5.90
P-47______ 5.60
P-51______ 5.88
F2A_______5.86
F4F_______5.55
F4U______ 5.35
F6F_______5.49
Reluctant Poster
Tech Sergeant
- 1,776
- Dec 6, 2006
Early skip bombing was tried with B-17s
Valor: Skip-Bombing Pioneer | Air & Space Forces Magazine
In the fall of 1942, a better way of sinking Japanese ships had to be found. Ken McCullar was one of the first to master the new tactic.
www.airforcemag.com
Geoffrey Sinclair
Staff Sergeant
- 1,271
- Sep 30, 2021
Been looking for a reference for the B-17A to D bomb bays and what changed to the E, no success, the B-17E at least plus the B-24 bomb bays were made for a maximum load of 8x1,600 pound AP, which limited the B-17 to 6,000 pounds and the B-24 to 8,000 pounds of HE bombs internally. Given when both types entered production design would have been in the 1939 to 1941 period. Also no success is a good list with dates for USAAF pre war bomb types and weights. The RAF listed its Fortress I maximum bomb load as 7,400 pounds with normal at 5,000 pounds, while giving the following alternatives, 2x2,000 pound, 4x1,100 pound and 8x600 pound.
Correct about the turbo chargers, but the PB4Y-2 data I reported was for the same altitude as the PB4Y-1.
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Shortround6
Lieutenant General
I just have a personal hang up with the 1600lb bomb as it seems to get into all kinds of discussions and bomb capacity lists or other things.
More pounds of ink has probably been wasted on the 1600lb bomb than the weight of 1600lbs dropped in WW II
Unless you were attacking a target with 5in of more of steel armor on top it was a pretty useless bomb.
I believe under 300 (Closer to 200?) were dropped in Europe in WW II. The 1600lb AP bomb held less explosive than a US 500lb GP which makes it a really poor choice for bombing much of anything except a heavily armored target.
The 1600lb bomb gets trotted out whenever there is a discussion about the SBD but there is no evidence that the SBD ever carried a 1600lb from a flight deck and probably never carried one from a shore base either, at least in combat.
You can find specifications for P-61 Night fighters that list four 1600lb AP bombs. P-61s were used for bombing at times but the 1600lb combination makes zero sense even if the racks were rated for that weight. If you are trying to hit a 5in steel deck (or equivalent concrete) it might help if you could see the target and not be dropping at night?
Or to actually have a bomb sight in day time?
You can lists that have the P-38 carrying a pair of 1600lb AP bombs ( I have no idea if they ever carried a 1600lb in combat)
Drop parameters for the 1600lb AP bomb to actually get through 5in of Class B Armor was 7500ft in level flight or 4500ft at 300kts in a 60 degree dive. From higher altitudes it would get through 7in if dropped high enough. Now find that patch of 5-7in armor from 1 1/2 to 2 miles up in the sky if it is not a really big ship.
Part of the popularity of the 1600lb was that due to it's size and the bomb shackles it fit on, it would 'fit' anywhere a 1000lb GB bomb would. In fact due to it's smaller diameter you could sometimes fit more bombs (4 in a rack instead of 3). Of course now you had to get the heavier load off the ground, hopefully with enough fuel that you could clear the fence at the end of the runway.
And that seems to be the story of the 1600lb AP bomb. Some were used against the Tirpitz, a few were used on other hard targets but it was actually dropped very little.
And like I said, the Idea the bombers that intercepted the Rex were being "sold" as carrying multiple 1600lb bombs when they used 930hp engines compared to the 12000hp
engines of the B-17E seems to employ too much of the time machine.
Of course in 1938 the need for 1600lb AP bombs was rather limited. The Bismarck had been laid down but wouldn't even be launched until 1939 let alone completed and the Japanese were keeping the Yamato secret.
There was no doubt the AAF and Boeing were trying to sell the B-17 as a hemisphere defensive weapon, I just doubt it was using the 1600lb bomb until several years later.
From reading about the US planes of the 30s it seems they used bombs sized in multiples of 300lbs rather than 250lbs.
Like 300, 600, 1100 rather than 250, 500, 1000.
Once you get past the 1100lb bombs things get a little tough to pin down. Of course for most of the 1930s and using the B-10 series of bombers you weren't going to carry much of anything bigger than 1100lbs although there may have been purchases of a few experimental batches?
Geoffrey Sinclair
Staff Sergeant
- 1,271
- Sep 30, 2021
Understandable, but without pre war data on B-17 bomb bays and available bombs not resolvable, the confirmed story starts in 1939/40. The MacArthur-Pratt agreement in January 1931 gave the AAC a coastal defence role at least.
The USAAF Statistical Digest says 1,222 x 1,600 pound AP bombs dropped, 1943 to 1945 inclusive, all in the European or Mediterranean Theatres, all in 1944. None dropped in theatres versus Japan. The B-17 raids run by Bomber Command dropped only 1,100 pound HE.
The War Production Board report, which starts in July 1940, reports no AP bombs made until January 1942, when 53 1,600 pound mark I were made for the Navy, it took until September for some to be made for the USAAF. Production for the USN ended in October 1943, apart from some made in June and July 1944, similarly production for the USAAF shut down in December 1943, apart from some in May 1944. All up 11,119 for the USAAF and 10,444 for the USN. The 1,000 pound AP bombs began production in March 1942. However according to the War Production Board the US was producing usually under 500 tons of bombs a month July 1940 to March 1941, including none in December 1940, and the totals include USN depth bombs, 500, 300 and 100 pound bombs seem to make up production but as the individual totals are so small compared with later entries they are all reported as zero, result is a number of bombs might have had limited quantity runs during the period but not be explicitly reported (There are no Tallboys or Grand Slams), in any case there is no column for 1,100 pound bombs. By the way in 1942 the report has 1,468 M63 1,400 pound AP bombs made, other limited AP bomb production were the 900 pound M60 the 800 pound M61 and the 600 pound M62.
Looks like the pre war USN dive bombers, the BG-1, SBU, SB2U and BT are generally quoted as carrying a 500 or 1,000 pound bomb which implies there were stocks of such bombs in the 1930's and some AP bombs would exist. For the SBD, all but the SBD-6 have performance charts carrying a 1,600 pound bomb, all except the SBD-1 have a reduced fuel load when doing so. The take off run in calm conditions for the SBD-1 with a 500 pound bomb was 770 feet, with the 1,600 pound bomb 1,050 feet and even with reduced fuel loads the 1,600 pound load is usually the longest take off run.
According to the USN its carrier based aircraft dropped no AP bombs in 1942, then 10 tons in 1943, 264 tons in 1944 and 29 tons in 1945, land based aircraft 7 tons in 1945. It does not break the AP bombs category down by weight, the notes to 1945 say largely 1,000 pounds and the land targets were transportation and harbor areas, ships were warships and also merchant ships over 500 tons.
9th Air Force P-61, 6 x 1000 GP HE, 14 x 500 GP HE, 13 x 1100 FB Incendiary, 44 x 750 FB Incendiary, 16 x 500 FB Incendiary, 79 x 500 IB Incendiary, 2 x 280 FB Incendiary, 2 x 250 IB Incendiary and 273 rockets, plus 1 x 1100 FB Incendiary, 2 x 500 FB Incendiary, 2 x 500 IB Incendiary and 2 rockets jettisoned.
I would say there was a need for heavy AP bombs in 1938. Hemisphere defence in the 1930's was implicitly resisting a Japanese attack, the IJN had 9 battleships and a heavy cruiser force, as the battleships were reconstructed in the 1930's they generally had the elevation of their main guns increased, which in turn required more deck armour to resist long range hits, armour that would also resist bombs.
I have no idea what the US thought during the 1920's and 1930's about aircraft sinking merchant ships, given the prize rules for submarines included ideas about safety of the civilian crews, my understanding is the public definition of hemisphere defence was sinking approaching enemy warships, especially the big ones. No one was going around talking of wiping out convoys or sinking tens of thousands of tons of merchant ships, they were talking about sinking lots of battleships. With at times pointing out the land based aircraft could carry larger numbers of the heavier bombs needed for the bigger ships and hitting them further offshore.
The B-10 from early 1936 seems to have topped out at about a pair of 1,100 pound bombs, the B-18 from mid 1937 had a bigger bomb load, the B-18A from mid 1938 could carry 6,500 pounds of bombs (no, probably not 4x1,600 pound AP)
The conclusion is the USAAF B-17 ended up optimised for carrying a specific AP bomb (and possibly AP bombs from the start) which carried over to the B-24.
This may have been posted elsewhere, but about five years ago there was a PBS Episode of "Secrets of the Dead" (I believe) that search for a downed B-17 near Greece. During the search they did find a submerged B-24 and went into some detail about the B-24's tendency for the nose section to crumple up and kill the flight crew.
I'm of the opinion that you needed all three bombers and they weren't redundant.
I can certainly agree with this but I also think that if I were a bomber crewman, especially pilot, in WWII, I'd rather be on one of the Boeings than the other two!
I can certainly agree with this but I also think that if I were a bomber crewman, especially pilot, in WWII, I'd rather be on one of the Boeings than the other two!
I would have preferred to be be a PB4Y-1 crew member from a Navy VP squadron patrolling the Pacific than one from a 8th Air Force B-17 in 1943.
ThomasP
Chief Master Sergeant
The B-17 was not designed with any particular AP bomb in mind. In fact, as far as I have been able to find there were no standard USAAC AP bombs before the early-war converted artillery projectiles. The reason the B-17 was able to carry 8x 1600 lb AP was due to the small diameter of the 1600 lb AP bomb body. The pre-war USAAC 600 lb Demolition bomb and war-time 500 lb GP bombs had body diameters larger than the 1600 lb AP which had a Ø14.0" body. Hence, in terms of space, any hanger position in the bay that could carry a 600 lb Demolition bomb could carry a 1600 lb AP bomb - they just used the heavier duty bomb stations/hangers as needed per the space required for clearance.
The original bombs around which the B-17 bomb bay was designed were the USAAC demolition series that came in 100 lb, 300 lb, 600 lb, 1100 lb, and 2000 lb sizes. The pre-war Navy series were of the 100 lb, 500 lb, and 1000 lb sizes. For commonality of production and ability to carry any bombs in service, the Army and Navy established the AN system in 1940 (I think). The USAAC/USAAF continued using its pre-war demolition series until they were out of production and all used up (though they were still using small numbers of 300 lb M31 in 1944 due to the large number produced).
USAAC/USAAF (pre-war)
2000 lb Dem M34___________ Ø23.3"
1100 lb Dem M33___________ Ø19.8"
600 lb Dem M32____________ Ø15.2"<
300 lb Dem M31____________ Ø10.9"
100 lb Dem M30______________Ø8.2"
USAAC(?)/USAAF (early-war, all converted from artillery projectiles)
1400 lb AP M63____________Ø14.0"
1000 lb AP M52____________Ø12.0"
800 lb AP M62_____________Ø12.0"
600 lb AP M61_____________Ø10.0"
Navy (pre-war)
1000 lb Mk 13 GP___________ Ø17.7"
500 lb Mk 12 GP____________ Ø14.2"<
100 lb Mk 4 GP_______________Ø8.0"
100 lb Mk 1 GP_______________Ø7.9"
Army/Navy (beginning in 1940)
2000 lb GP AN-M34 & M64___ Ø23.3"
1000 lb GP AN-M44 & M65___ Ø18.8"
500 lb GP AN-M43 & M64____ Ø14.2"<
250 lb GP AN-M57___________Ø10.9"
100 lb GP AN-M30____________Ø8.2"
1600 lb AN-AP Mk 1__________Ø14.0"<
1000 lb AN-AP M33__________ Ø12.0"
1000 lb SAP AN-M59_________ Ø15.1"
500 lb SAP AN-M58__________ Ø11.8"
NOTE: There were some much earlier Army bomb designs from the mid-1920s, but aside from the Demolition and Chemical series, none became standard or were produced in any numbers. An example of one of the earlier Army series Demolition bombs is:
Army (mid-1920s)
1100 lb Dem Mk III___________Ø20.0"
Here is the original B-17D bomb bay arrangement and designed/expected bomb loads:
Here is the war-time B-17F bomb bay arrangement and expected bomb loads:
Sorry for the fuzzy B-17F diagram but something happened in translation from the original image
The original bombs around which the B-17 bomb bay was designed were the USAAC demolition series that came in 100 lb, 300 lb, 600 lb, 1100 lb, and 2000 lb sizes. The pre-war Navy series were of the 100 lb, 500 lb, and 1000 lb sizes. For commonality of production and ability to carry any bombs in service, the Army and Navy established the AN system in 1940 (I think). The USAAC/USAAF continued using its pre-war demolition series until they were out of production and all used up (though they were still using small numbers of 300 lb M31 in 1944 due to the large number produced).
USAAC/USAAF (pre-war)
2000 lb Dem M34___________ Ø23.3"
1100 lb Dem M33___________ Ø19.8"
600 lb Dem M32____________ Ø15.2"<
300 lb Dem M31____________ Ø10.9"
100 lb Dem M30______________Ø8.2"
USAAC(?)/USAAF (early-war, all converted from artillery projectiles)
1400 lb AP M63____________Ø14.0"
1000 lb AP M52____________Ø12.0"
800 lb AP M62_____________Ø12.0"
600 lb AP M61_____________Ø10.0"
Navy (pre-war)
1000 lb Mk 13 GP___________ Ø17.7"
500 lb Mk 12 GP____________ Ø14.2"<
100 lb Mk 4 GP_______________Ø8.0"
100 lb Mk 1 GP_______________Ø7.9"
Army/Navy (beginning in 1940)
2000 lb GP AN-M34 & M64___ Ø23.3"
1000 lb GP AN-M44 & M65___ Ø18.8"
500 lb GP AN-M43 & M64____ Ø14.2"<
250 lb GP AN-M57___________Ø10.9"
100 lb GP AN-M30____________Ø8.2"
1600 lb AN-AP Mk 1__________Ø14.0"<
1000 lb AN-AP M33__________ Ø12.0"
1000 lb SAP AN-M59_________ Ø15.1"
500 lb SAP AN-M58__________ Ø11.8"
NOTE: There were some much earlier Army bomb designs from the mid-1920s, but aside from the Demolition and Chemical series, none became standard or were produced in any numbers. An example of one of the earlier Army series Demolition bombs is:
Army (mid-1920s)
1100 lb Dem Mk III___________Ø20.0"
Here is the original B-17D bomb bay arrangement and designed/expected bomb loads:
Here is the war-time B-17F bomb bay arrangement and expected bomb loads:
Sorry for the fuzzy B-17F diagram but something happened in translation from the original image
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Reluctant Poster
Tech Sergeant
- 1,776
- Dec 6, 2006
The weak bomb-bay doors were a real problem.
From B-24 By Graham Simons:
"Top turrets were not the only concern. Little chance of crew survival in a water landing was one area where rumor was not far from reality. The poor ditching characteristics of the Liberator were subject to investigation both in the United States and Britain but there was no really satisfactory solution other than a major re-design of the whole fuselage. In operational theaters strengthening struts were devised which took the form of bearers that could be quickly installed if a water landing was imminent. Late production B-24s had four such bomb-bay stiffeners as standard equipment and it is probable the they helped with the slightly improved number that escaped from successful ditching."
I cannot imagine trying to install struts in the bomb-bay while the aircraft is going down.
As for the turret issue:
"It was even more evident in a large number of incidents were a Liberator suffered nose wheel collapse on landing, when the nose ploughed into the runaway, with the pilots and others on the flight deck than being crushed by the top turret."
It turned out the turret didn't actually break loose, but rather that the fuselage failed between the cockpit and the turret.
buffnut453
Captain
Here's a well-known example of the B-24 flipping onto its nose:
In a word....OUCH!!!
In a word....OUCH!!!
Greg Boeser
1st Lieutenant
I thought that was an early VTOL experiment.
drgondog
Major
The dominant B-24 structural flaw during ditching was breaking the airplane in half at the aft bulkhead of bomb bay.
Reluctant Poster
Tech Sergeant
- 1,776
- Dec 6, 2006
The 1000 lb and 1600 lb AP bombs were designed by the USN after the start of WWII:
The AP bombs the USAAF entered the war with were converted seacoast artillery projectiles.
- Thread starter
- #298
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
Different construction designs.
Also, the B-17 had a better ditching survivability because of the shape of the fuselage, low wing placement and a stall speed of about 80mph.
The B-24's stall speed was just about 100mph and the nose of the B-24 had the turret up high, lots of narrow framing for the Bombardier station, which would not offer much resistance when it hit the water, and that, coupled with the high wing meant the B-24 would be submerged before the main-wing offered resistance to the water as it ditched.
Shortround6
Lieutenant General
Thank you so much for provided those drawings.
They do clear up a number of things.
