Bomb and Bomb-Bay Sizes

[MiTasol]

This is going to depend on the bomb size and the plane.
The actual problem is getting crewman's hand/arm around the bomb to the lug/fitting to fasten the bomb in place. Also to fit the safety wires from the bomb rack to the fuses. And detach the bomb hoist cables from the larger bombs. With small bombs crewman may only to get his hand/arm around the bomb while sitting/kneeling/whatever under the bomb. Once they were dealing with large bombs (needs elbow along side the bomb or shoulder?) you need more 'clearance'. Some aircraft, like the B-17s, B-24s, B-26s had a walkway separating the left and right stacks of bombs and the crewmen could stand/kneel on the walkway and work on the top of the bombs. Some British bombers had access holes in the bomb bay ceiling for the bomb hoists to go through and for doing the fiddley bits with the latches/safety wires.

Another thing for 'clearance' is the angle at which the bombs could be dropped. Bombers could drop bombs at different angles of flight. Diving, climbing and/or banked. Some bombers had more latitude than others.

With a lot of British aircraft the bomb was attached to the rack on the ground and then the whole assembly winched into the aircraft. This made it very easy to adjust the sway braces that the RAF used on most, if not all, bombers. The first two items below are Beaufort where the 1,000lb and smaller bombs are lifted complete with rack and 2,000lb bombs and torpedoes are lifted after the rack is installed but by using winches built into the rack.

The Lancaster "small" bomb configuration - essentially the same

The Lancaster 8,000lb configuration

The sway braces (crutches) as used on 4 and 8,000lb bombs.

 

[MiTasol]

The Wellington originally had 2 bomb beams, dividing the bomb bay into 3. One beam had bombs hung on both sides, while the other had bombs hung on the outside.

https://upload.wikimedia.org/wikipedia/commons/6/69/Wellington_bomb_bay_India_WWII_IWM_CF_135.jpg

The bomb bay on the left is full of small bomb containers, what today would be called cluster bombs.

 

[CD Baumann]

Edit:
Man did I open a can of worms! I didn't even think I had said anything that controversial. Remind me to check my account regularly because I don't even know where to begin!

Anyway, that's actually a very good question and it depends on how the bomb bay is set up and how the bombs are stacked. I'm sure we're all familiar with the Lancaster's cavernous bomb bay. Well the bombs were stacked horizontal and parallel to each other like this:

So because she had a long bay she could carry monstrous bombs like the 10,000lb tall boy ( correction 12,000 lb)

The B17 's bomb bay was stacked vertically like this

With a cat walk and wing structure going through although believe it or not, a according Greg's airplanes, square footage wise the Lanc's bomb bay wasn't much bigger than the Forts though he didn't give a number. But because her bombs were stacked vertically it ruled out carrying really big bombs although weight wise the Fort could handle it. Still, contrary to popular belief, the B17's max bombload was 12,800 lbs not 4,000lbs. The latter was her minimum useful bombload.

 

[Shortround6]

The bomb bay on the left is full of small bomb containers, what today would be called cluster bombs.

I think modern terminology would be bomb dispenser/s.

Most of the time cluster bombs refer to a container that is dropped and at some time after it leaves the aircraft the container opens up dispersing the bombs.
Bomb dispensers stay attached to the aircraft for reuse after the bombs/mines are released. Most modern jets (all?) can jettison the dispenser/s if needed (more speed or more range?)
I believe the British SBC was supposed to stay with the aircraft?

I am not sure how strict the terminology is, with the internet (and press articles) things may get blurry.

 

[MiTasol]

You are correct on both counts. Dispersers would be a far more accurate description of the SBC and although it could, like the racks that were fitted prior to loading, be jettisoned with some difficulty, it normally stayed with the aircraft.

 

[wuzak]

That's actually good question and it depends on how the bomb bay is set up and how the bombs are stacked. I'm sure we're all familiar with the Lancaster's cavernous bomb bay. Well the bombs were stacked horizontal and parallel to each other like this:
View attachment 791844
So because she had a long she could carry monstrous bombs like the 10,000lb tall boy.

The Tallboy was 12,000lb nominal weight.
They could also use the 12,000lb HC bomb.

In both cases, the bomb bay doors had to be modified to fit them.

The B17 's bomb bay was stacked vertically like this
View attachment 791845
Believe it or not, a according Greg's airplanes, square footage wise the lanc's bomb bay wasn't much bigger than the Forts though he didn't give a number. But because her bombs were stacked vertically it ruled out carrying really long, super heavy bombs although weight wise the Fort could more handle it. Still, contrary to popular believe, the B17's nax bombload was 12,800 lbs not 4,000lbs. The latter was her minimum bombload.

Technically, the biggest bomb load that could be hung on a B-17 was 17,600lb - 6 x 1,600 SAP + 2 x 4,000lb LC (Us equivalent to 4,000lb HC Cookie) under the inner wings.

But good luck getting that much farther than the French coast from England.

The 12,800lb max you quote would be for 6 x 1,600lb SAP internally and 2 x 1,600lb SAP under the inner wings.

The 1,600lb SAP bomb was not widely used by the Eighth Air Force.

Having bombs under the wings negatively impacted the range.

The biggest bomb that could be carried internally with that rack was the 2,000lb GP. And only on two stations.

Carrying the 2,000lb GP bomb exclusively means a maximum of 4,000lb internally. Stations above the 2,000lb could be used to carry smaller bombs or incendiaries, but I'm not sure which stations were available.

The maximum useful internal load would be 8 x 1,000lb GP = 8,000lb total.

But how far the target is will affect the bomb load.
On the first Schweinfurt raid (IIRC), for example, the bombers carried 5 or 6 x 1,000lb GP bombs each.

If the bomb of choice is 500lb GP, 12 can be carries internally = 6,000lb.

If I am reading the chart correctly, the B-17 had 18 stations that could be loaded with 250lb bombs (or up to 300lb actually). That is a load of 4,500lb (5,400lb for 300lb bombs).

You can see that more smaller bombs can be carried, but that reduces the load that can be carried.

The Lancaster, in contrast, could carry 14 x 1,000lb MC (equivalent to US 1,000lb GP) bombs. This was possible using the bomb with a shortened tail.

The B-17 was limited by its mid 1930s requirement to carry the smaller mid 1930s bombs.

The Lancaster was capable of carrying the bigger bombs because its mid 1930s requirements included the option of carrying two large torpedoes.

Believe it or not, a according Greg's airplanes, square footage wise the lanc's bomb bay wasn't much bigger than the Forts though he didn't give a number.

I suppose that if you calculated the area of the B-17's racks the total may be similar to the Lancaster's.

But I don't think that is a direct comparison.

Still, contrary to popular believe, the B17's nax bombload was 12,800 lbs not 4,000lbs. The latter was her minimum bombload.

The claim was never that the B-17's maximum bombload was 4,000lb, but that was the average bomb load.

It really does depend on the size and type of the bombs being carried.

The minimum bomb load was, of course, 0lb.

 

[CD Baumann]

The Tallboy was 12,000lb nominal weight.
They could also use the 12,000lb HC bomb.

In both cases, the bomb bay doors had to be modified to fit them.




Technically, the biggest bomb load that could be hung on a B-17 was 17,600lb - 6 x 1,600 SAP + 2 x 4,000lb LC (Us equivalent to 4,000lb HC Cookie) under the inner wings.

But good luck getting that much farther than the French coast from England.

The 12,800lb max you quote would be for 6 x 1,600lb SAP internally and 2 x 1,600lb SAP under the inner wings.

The 1,600lb SAP bomb was not widely used by the Eighth Air Force.

Having bombs under the wings negatively impacted the range.

The biggest bomb that could be carried internally with that rack was the 2,000lb GP. And only on two stations.

Carrying the 2,000lb GP bomb exclusively means a maximum of 4,000lb internally. Stations above the 2,000lb could be used to carry smaller bombs or incendiaries, but I'm not sure which stations were available.

The maximum useful internal load would be 8 x 1,000lb GP = 8,000lb total.

But how far the target is will affect the bomb load.
On the first Schweinfurt raid (IIRC), for example, the bombers carried 5 or 6 x 1,000lb GP bombs each.

If the bomb of choice is 500lb GP, 12 can be carries internally = 6,000lb.

If I am reading the chart correctly, the B-17 had 18 stations that could be loaded with 250lb bombs (or up to 300lb actually). That is a load of 4,500lb (5,400lb for 300lb bombs).

You can see that more smaller bombs can be carried, but that reduces the load that can be carried.

The Lancaster, in contrast, could carry 14 x 1,000lb MC (equivalent to US 1,000lb GP) bombs. This was possible using the bomb with a shortened tail.

The B-17 was limited by its mid 1930s requirement to carry the smaller mid 1930s bombs.

The Lancaster was capable of carrying the bigger bombs because its mid 1930s requirements included the option of carrying two large torpedoes.




I suppose that if you calculated the area of the B-17's racks the total may be similar to the Lancaster's.

But I don't think that is a direct comparison.




The claim was never that the B-17's maximum bombload was 4,000lb, but that was the average bomb load.

It really does depend on the size and type of the bombs being carried.

The minimum bomb load was, of course, 0

The Tallboy was 12,000lb nominal weight.
They could also use the 12,000lb HC bomb.

In both cases, the bomb bay doors had to be modified to fit them.




Technically, the biggest bomb load that could be hung on a B-17 was 17,600lb - 6 x 1,600 SAP + 2 x 4,000lb LC (Us equivalent to 4,000lb HC Cookie) under the inner wings.

But good luck getting that much farther than the French coast from England.

The 12,800lb max you quote would be for 6 x 1,600lb SAP internally and 2 x 1,600lb SAP under the inner wings.

The 1,600lb SAP bomb was not widely used by the Eighth Air Force.

Having bombs under the wings negatively impacted the range.

The biggest bomb that could be carried internally with that rack was the 2,000lb GP. And only on two stations.

Carrying the 2,000lb GP bomb exclusively means a maximum of 4,000lb internally. Stations above the 2,000lb could be used to carry smaller bombs or incendiaries, but I'm not sure which stations were available.

The maximum useful internal load would be 8 x 1,000lb GP = 8,000lb total.

But how far the target is will affect the bomb load.
On the first Schweinfurt raid (IIRC), for example, the bombers carried 5 or 6 x 1,000lb GP bombs each.

If the bomb of choice is 500lb GP, 12 can be carries internally = 6,000lb.

If I am reading the chart correctly, the B-17 had 18 stations that could be loaded with 250lb bombs (or up to 300lb actually). That is a load of 4,500lb (5,400lb for 300lb bombs).

You can see that more smaller bombs can be carried, but that reduces the load that can be carried.

The Lancaster, in contrast, could carry 14 x 1,000lb MC (equivalent to US 1,000lb GP) bombs. This was possible using the bomb with a shortened tail.

The B-17 was limited by its mid 1930s requirement to carry the smaller mid 1930s bombs.

The Lancaster was capable of carrying the bigger bombs because its mid 1930s requirements included the option of carrying two large torpedoes.




I suppose that if you calculated the area of the B-17's racks the total may be similar to the Lancaster's.

But I don't think that is a direct comparison.




The claim was never that the B-17's maximum bombload was 4,000lb, but that was the average bomb load.

It really does depend on the size and type of the bombs being carried.

The minimum bomb load was, of course, 0lb.

The tall boy weight: my mistake.

I've seen many people claim that 4k was the Fort' nac load. Anyway, 0 lbs is not a bombload and the USAAF considered 4,000lbs to be the minimum useful bombload. However, the Fort's bomb load ranged any where from 4 to 10,000lbs ( if we count a pair of Disney bombs). Looking at the chart for her internal bay alone there are stations for up to 8 1600 lb bombs,

which is 12,800. Yes I know you stated the 1600lbs bomb was rarely used but we're talking capability. If you check the manual for the B17f with 6,000 lbs in the bomb bay and 8,000 on external wing racks (14,000lbs) she had a range of 1170 miles IIRC. I think this was enough to reach just about any target in Germany. So it'd be reasonable to assume with the 12,800 lb load she had enough range to be useful. However, to get this range it would have meant dropping the altitude and flying straight in and out of target area.

During the so -called Battle of Berlin Bomber Harris did order all Lancs to be loaded with 14,000lbs of bombs. Not only did the altitude have to be lowered to 18,000 feet but they also had to fly in a straight line to and from Berlin! This not only put them in accurate flak range but the Luftwaffe was also very quick to catch on and plan accordingly. Casualties sky rocketed.

It should also be noted that during the infamous Augsburg daylight raid of 1942, the Lancaster's combat debut, the Lancs were only loaded to 4,000lbs. It should also be said that as the allies gained aur superiority, both the Forts and Liberators bombload went up as they dropped the altitude was lowered to 10,000 feet on many occasions.

 

[Shortround6]

The 1,600lb SAP bomb was not widely used by the Eighth Air Force.

The 1600lb bomb was not an SAP bomb, it was an AP bomb with a minimal HE load.
Sometimes given as 209lbs (13%) so unless you are trying to go through really, really thick steel or concrete it was sort of dud for normal buildings. A US 500lb HE bomb carried more explosive.

I suppose that if you calculated the area of the B-17's racks the total may be similar to the Lancaster's.

I think you are right, why anybody is comparing square footage of bomb bay area I have no idea, unless they are trying to skew the result.
Cubic feet of bomb bay (volume) would be a better idea of the possibilities, limited by actual racks and/or other obstructions (like the US walkways)

The claim was never that the B-17's maximum bombload was 4,000lb, but that was the average bomb load.

This is another case of using a obscure actual "fact" to get across a certain view point and rather skewed at that.
Due to the bomb bay shape and racks of the B-17 it didn't have enough room for large numbers of "light" bombs. In this case incendiaries. Incendiaries are light for their length/diameter and the B-17 simply didn't have enough room for more than around 3000lbs worth or little over. Raids where B-17s took a little over 3000lbs worth of incendiaries to a target, other B-17s in the same squadron or group were carrying 5000lbs of HE bombs. (ten 500lb or 5 1000lb bombs) and using rather rough math you get the 4000lb "average".

You will find different bomb load charts for the B-17 showing either six or eight stations for the 1600lb bombs depending on actual model and perhaps the actual racks installed. Which is a total whitewash of what was going on. The total number of 1600lbs dropped on Europe was in the hundreds according to most sources, sometimes it is just over 1000,
In the scale of bombs dropped on Europe that is a truly insignificant number and a number of them were dropped on sub pens or other "hard" targets and not general bombardment.
The 1600lb bomb has seen more ink used/wasted on it than just about any other weapon of WW II. We even know how many you could fit under a P-61 night fighter. Why you would try to use a night fighter to drop anti-battleship bombs has never been explained
Or how?

The US had no bombs in-between the 1600lb bomb and the 1000lb bomb and since the 1600lb bomb fit the same lugs and was around 4-5in smaller in diameter that the 1000lb HE bombs it fit into a lot of places (it was a bit longer) and for the US the vertical stacking it made them sound like they could carry a lot. Four 14in dia bombs (56in) vs three 18.6in (55.8in) bombs.

 

[CD Baumann]

The 1600lb bomb was not an SAP bomb, it was an AP bomb with a minimal HE load.
Sometimes given as 209lbs (13%) so unless you are trying to go through really, really thick steel or concrete it was sort of dud for normal buildings. A US 500lb HE bomb carried more explosive.

I think you are right, why anybody is comparing square footage of bomb bay area I have no idea, unless they are trying to skew the result.
Cubic feet of bomb bay (volume) would be a better idea of the possibilities, limited by actual racks and/or other obstructions (like the US walkways)

This is another case of using a obscure actual "fact" to get across a certain view point and rather skewed at that.
Due to the bomb bay shape and racks of the B-17 it didn't have enough room for large numbers of "light" bombs. In this case incendiaries. Incendiaries are light for their length/diameter and the B-17 simply didn't have enough room for more than around 3000lbs worth or little over. Raids where B-17s took a little over 3000lbs worth of incendiaries to a target, other B-17s in the same squadron or group were carrying 5000lbs of HE bombs. (ten 500lb or 5 1000lb bombs) and using rather rough math you get the 4000lb "average".

You will find different bomb load charts for the B-17 showing either six or eight stations for the 1600lb bombs depending on actual model and perhaps the actual racks installed. Which is a total whitewash of what was going on. The total number of 1600lbs dropped on Europe was in the hundreds according to most sources, sometimes it is just over 1000,
In the scale of bombs dropped on Europe that is a truly insignificant number and a number of them were dropped on sub pens or other "hard" targets and not general bombardment.
The 1600lb bomb has seen more ink used/wasted on it than just about any other weapon of WW II. We even know how many you could fit under a P-61 night fighter. Why you would try to use a night fighter to drop anti-battleship bombs has never been explained
Or how?

The US had no bombs in-between the 1600lb bomb and the 1000lb bomb and since the 1600lb bomb fit the same lugs and was around 4-5in smaller in diameter that the 1000lb HE bombs it fit into a lot of places (it was a bit longer) and for the US the vertical stacking it made them sound like they could carry a lot. Four 14in dia bombs (56in) vs three 18.6in (55.8in) bombs.

I think we're missing the point. I'm not talking about what bombs were or were not used, I'm talking about bomb load capability.
And this page

Is straight from the B17 manual which shows 8 stations for a 1600 lb bombs. There's no incentive to lie about anything, people lives were at stake and there was a war to be won.

 

[MiTasol]

Believe it or not, a according Greg's airplanes, square footage wise the lanc's bomb bay wasn't much bigger than the Forts though he didn't give a number. But because her bombs were stacked vertically it ruled out carrying really long, super heavy bombs although weight wise the Fort could more handle it. Still, contrary to popular believe, the B17's nax bombload was 12,800 lbs not 4,000lbs. The latter was her minimum bombload.

That may be almost true but what you are missing, and Greg will never admit, is the Lanc bomb bay is an Olympic swimming pool with no impedances and the B-17 bomb bay is a mixture of 2 water tanks and 2 (external) toddlers pools with big fat walls dividing them.

They may be the same "size" but you have far far more flexibility with, and in, an Olympic pool than you do in 2 water tanks and 2 toddlers pools

 

[Shortround6]

Is straight from the B17 manual which shows 8 stations for a 1600 lb bombs. There's no incentive to see anything, people lives were at stake and there was a war to be one

There was a war to be won and it wasn't done with 1600lb AP bombs.
The B-17 could hold, inside six 1000lb HE bombs or twelve 500lb HE bombs.
Counting bombs that most bomb groups never saw in their entire history doesn't get us very far.
B-17 could lift 10,000 to 14,000lbs using the under wing racks of HE bombs or 8000lbs if you wanted the bombs to land close to each other.
You can find all sorts of paperwork/load charts for Douglas SBDs with 1600lb bomb under the fuselage. What you can't find is accounts of them actually dropping that bomb in action.
You are hard pressed to find accounts of the 1600lb being dropped by either Avengers or Helldivers. One reason is that some US carriers only had space for about 20 in their magazines, assuming they even had any to put in the spaces in the magazine.
And we are contributing to the waste of ink/elections about this bomb.

 

[CD Baumann]

That may be almost true but what you are missing, and Greg will never admit, is the Lanc bomb bay is an Olympic swimming pool with no impedances and the B-17 bomb bay is a mixture of 2 water tanks and 2 (external) toddlers pools with big fat walls dividing them.

They may be the same "size" but you have far far more flexibility with, and in, an Olympic pool than you do in 2 water tanks and 2 toddlers pools

Ummm, what was said was that in terms of square footage the Forts bomb bay wasn't that much smaller. It never denied that the Lanc's was uninterrupted or more versatile.

And how does that stop the B17 from being capable of having a 12,800lb bomb load?

 

[CD Baumann]

There was a war to be won and it wasn't done with 1600lb AP bombs.
The B-17 could hold, inside six 1000lb HE bombs or twelve 500lb HE bombs.
Counting bombs that most bomb groups never saw in their entire history doesn't get us very far.
B-17 could lift 10,000 to 14,000lbs using the under wing racks of HE bombs or 8000lbs if you wanted the bombs to land close to each other.
You can find all sorts of paperwork/load charts for Douglas SBDs with 1600lb bomb under the fuselage. What you can't find is accounts of them actually dropping that bomb in action.
You are hard pressed to find accounts of the 1600lb being dropped by either Avengers or Helldivers. One reason is that some US carriers only had space for about 20 in their magazines, assuming they even had any to put in the spaces in the magazine.
And we are contributing to the waste of ink/elections about this bomb.

What part of "I'm not discussing what bombs were or were not dropped... I'm talking pure lifting capability." do you not understand?

I'm saying that the B17 WAS CAPABLE of CARRYING EIGHT 1600lb bombs which is 12,800 lb which is the true maximum bomb load. It has nothing to to do with often the actual 1600lbs bomb it was dropped.

Now, how does not dropping very many 1600 lb bombs stop the B17 from being able to carry 12,800lbs?

 

[wuzak]

I've seen many people claim that 4k was the Fort' nac load.

Possibly when comparing the B-17 to the Mosquito.

And that the Mosquito could carry a 4,000lb bomb load to Berlin, which is what is often stated as the maximum load the B-17 could carry to Berlin.

Though it is more likely an average that they would take to Berlin, due to the types of bombs used.

Shortround6 mentioned it above.

Anyway, 0 lbs is not a bombload and the USAAF considered 4,000lbs to be the minimum useful bombload.

But often they carried less than 4,000lb.

I'd guess more often than they carried more than 6,000lb.

However, the Fort's bomb load ranged any where from 4 to 10,000lbs ( if we count a pair of Disney bombs). Looking at the chart for her internal bay alone there are stations for up to 8 1600 lb bombs,

The Disney bombs (developed by teh Royal Navy) were 4,500lb, so a total of 9,000lb.

When they were used it wasn't at very long ranges, and I would think without an internal bomb load - at least because the bombs that could be carried internally weren't much use against the tragets for teh Disney bomb.

The B-17 bomb load varied from 0lbs to the maximum bomb load, which was, in most instances, around 6,000lb with HE bombs.

Looking at the chart for her internal bay alone there are stations for up to 8 1600 lb bombs,

My mistake. I did not see the stations on the outside racks.

I do question whether one could be carried there when one is carried on the inner rack, They are almost directly opposite each other.

Can anyone confirm?

 

[Zipper730]

Barnes Wallis seems to have thought so as well. From a recent article in Aeroplane on the Windsor.

"....The Wellington and Warwick's geodetic structure had been relatively simple, but the Windsor wing geodetics required heavy back-to--back --channels at the root and lighter single channels outboard, which introduced many new and different joints, so any simplicity was lost.

What does he mean by "channels"?

Inner & outer wings had strengthened spars and geodetics
Strengthened aileron, fuselage and tailplanes structures.

I remember in a book (I think it was British Secret Projects) something that suggested the plane didn't have any spars (made more fuel space). I thought that was odd, I guess the book was wrong.

With a lot of British aircraft the bomb was attached to the rack on the ground and then the whole assembly winched into the aircraft.

So, the bomb was attached to the rack by a winch; then pulled right on up into the bay and attached to the sway brace which could either be pre-adjusted or adjusted afterwards?

 

[wuzak]

What does he mean by "channels"?

Strut channel - Wikipedia

en.wikipedia.org

 

[wuzak]

If you check the manual for the B17f with 6,000 lbs in the bomb bay and 8,000 on external wing racks (14,000lbs) she had a range of 1170 miles IIRC. I think this was enough to reach just about any target in Germany. So it'd be reasonable to assume with the 12,800 lb load she had enough range to be useful. However, to get this range it would have meant dropping the altitude and flying straight in and out of target area.

I find that doubtful.

Also, the range doesn't translate into reaching "just about any target in Germany".

So it'd be reasonable to assume with the 12,800 lb load she had enough range to be useful. However, to get this range it would have meant dropping the altitude and flying straight in and out of target area.

So why didn't they use bigger bomb loads.

During the so -called Battle of Berlin Bomber Harris did order all Lancs to be loaded with 14,000lbs of bombs. Not only did the altitude have to be lowered to 18,000 feet but they also had to fly in a straight line to and from Berlin! This not only put them in accurate flak range but the Luftwaffe was also very quick to catch on and plan accordingly. Casualties sky rocketed.

18,000ft was not a reduced altitude, but a normal altitude.

It should also be noted that during the infamous Augsburg daylight raid of 1942, the Lancaster's combat debut, the Lancs were only loaded to 4,000lbs. It should also be said that as the allies gained aur superiority, both the Forts and Liberators bombload went up as they dropped the altitude was lowered to 10,000 feet on many occasions.

Augsburg was also at low altitude.

And around 600-700 miles from England.

 

[MiTasol]

So, the bomb was attached to the rack by a winch; then pulled right on up into the bay and attached to the sway brace which could either be pre-adjusted or adjusted afterwards?

No. The bomb was attached to the rack, the sway braces (crutches in RAF speak) adjusted to fit and then the complete assembly winched into the aircraft. As you can see in post 43 there is no way that you could get your arms between the bomb and bomb bay skirt to adjust the sway braces in situ.

This part of Fig 4 in post 41 shows the bomb and rack attached to the cable and hanging about a foot below the installed position.

This part shows the assembly pulled all the way up

and this shows the swivel locking hook engaged in the loading link. Once the link is fully engaged the adjusting screw is screwed down firmly and then the cable tension is released. and cable and pulley cradle are moved to the next location. The spring loaded control for the adjusting screw works a bit like the direction control on a ratchet wrench. Move it one way and you can only tighten, move it the other way and you can loosen the adjusting screw.

The manual describes it thus. In (iii) it makes more sense with a comma after the word bomb or it said Fit the carrier to the bomb, adjust the crutches, set the fuse units and links.

This diagram from the RAF manual may describe it better. View D shows the rack and bomb assembly when it has just cleared the trolley.

 

[Geoffrey Sinclair]

Interesting how the B-17 capacity is measured using 1,600 pound AP bombs, given when the bombs were made, according to the War Production Board under 50 tons of AP bombs had been made to end December 1941, probably all 1,600 pound. The navy program January 1942 to October 1943 had 9,345 made plus 1,099 more in June and July 1944. The army program had 200 in September 1942, then 10,274 in 1943 and 645 in May 1944. The USAAF says it dropped 1,122 of the bombs in the ETO&MTO in 1944, none in operations against Japan. ETO&MTO operations dropped 6,284,271 HE bombs, including 148x4,500 pound and 1,645x550 pound Russian made bombs. The 9th Air Force reports its B-26 dropped 98x1,600 pound GP, not sure if that should be AP. The B-17F could carry 8x1,600 AP bombs internally, but apparently the B-17G was down to 6. In both cases the size of HE bombs normally restricted the internal HE load to 6,000 pounds. To get to 12,800 pounds of HE requires a large external load. Alternatively consider how many AP bombs a Lancaster could carry internally if set up for it. Why measure bomb bay sizes in square feet instead of cubic feet? By creating a pair of internal walls the B-17 had plenty of surface area at the expense of volume.

Lancaster combat debut 3/4 March 1942, minelaying 4x1,500 pound mines each, 10/11 March for bombing, 1,260x4 pound incendiaries each, people might be happy to know the Lancaster first dropped HE bombs during the daylight 17 April 1942 Augsburg raid while before that there had been 4 minelaying, 4 bombing and 1 leaflet days/nights of operations. Lancaster average bomb loads, pounds
4,286.79 1942 Day
6,222.35 1942 Night
10,976.00 1943 Day (1 sortie)
8,809.33 1943 Night
12,053.51 1944 Day
10,768.68 1944 Night
10,844.27 1945 German target, Day
9,331.14 1945 German target, Night
11,610.17 All war, day
9,525.47 All war, night

I have seen claims the B-17 could carry 12,800 pounds internally plus 8,000 pounds externally, but usually maximum bomb load is given as 17,600 pounds. The B-17G had about 30,000 pounds of load, the crew added about 2,000 pounds. The 5 tons lighter B-17F, with no external load could manage a combat radius of 320 miles with 1,760 gallons allowing adequate reserves using 8th Air Force tactics of climb high quickly, tight formation, fast cruise. B-17F warm up, take off and climb to 25,000 feet cost an hour and 380 gallons, then add a 20% penalty for the extra weight and drag of more bombs, then the drag penalty for an external load during cruise and finally the height penalty for carrying over 5 more tons of bombs when over the target.

Over the course of the campaign the 8th Air Force reports the average B-17 load was 5,139.38 pounds, B-24 5,320.96 pounds. For a fairly irrelevant statistic the average B-17 load in pounds was 4,248.2 HE, 739.9 Incendiary and 151.3 fragmentation, the B-24 4,442.7 HE, 718.4 incendiary, 159.9 fragmentation.

Richard Davis spreadsheets,
Mosquito sorties to Berlin 25 March 1944 to end of war, 125 spreadsheet entries, 5,621 attacking, 35 lost, 7,783 tons of bombs, 97.8% HE, average load 2,796.3 pounds. Even if the Mosquito could carry a 4,000 pound bomb it did not always do so, add pathfinders not dropping their full load plus there is the possibility of siren tours, 4 bombs, 4 cites .

8th Air Force Berlin raids, the spreadsheet does not distinguish between B-17 and B-24, 48 spreadsheet entries, which should fit into the number of characters posting limit,

City	Date	Atk	Lost	H.E.	I.B.	Frag	Total	average	%HE
Berlin	04-Mar-44	31	11	45.0	24.3	-	69.3	4,470.97​	64.94​
Berlin	06-Mar-44	351	44	602.5	237.0	-	839.5	4,783.48​	71.77​
Berlin/Potsdam	06-Mar-44	23	0	56.0	10.4	-	66.4	5,773.91​	84.34​
Berlin/Potsdam	06-Mar-44	19	4	47.5	-	-	47.5	5,000.00​	100.00​
Berlin/Spandau	06-Mar-44	19	4	47.5	-	-	47.5	5,000.00​	100.00​
Berlin/Spandau	06-Mar-44	6	0	15.0	-	-	15.0	5,000.00​	100.00​
Berlin/Templehof	06-Mar-44	12	0	36.0	-	-	36.0	6,000.00​	100.00​
Berlin/Erkner VKF	08-Mar-44	468	36	300.4	761.0	-	1,061.4	4,535.90​	28.30​
Berlin/Friedrichstrasse	08-Mar-44	30	0	23.8	51.3	-	75.1	5,006.67​	31.69​
Berlin	09-Mar-44	332	6	528.8	239.8	-	768.6	4,630.12​	68.80​
Berlin	22-Mar-44	621	12	512.0	862.2	-	1,374.2	4,425.76​	37.26​
Berlin/Basdorf	22-Mar-44	32	0	-	80.1	-	80.1	5,006.25​	0.00​
Berlin	29-Apr-44	581	46	711.5	712.0	-	1,423.5	4,900.17​	49.98​
Berlin	07-May-44	525	8	812.2	450.7	-	1,262.9	4,811.05​	64.31​
Berlin	08-May-44	384	13	768.2	146.6	-	914.8	4,764.58​	83.97​
Berlin	19-May-44	493	15	404.0	662.5	-	1,066.5	4,326.57​	37.88​
Berlin	24-May-44	459	33	428.2	605.0	-	1,033.2	4,501.96​	41.44​
Berlin	21-Jun-44	366	15	719.1	177.0	-	896.1	4,896.72​	80.25​
Berlin	21-Jun-44	194	5	381.2	93.7	-	474.9	4,895.88​	80.27​
Berlin/Marienfelde	21-Jun-44	30	3	44.5	31.8	-	76.3	5,086.67​	58.32​
Berlin/Niederschoneweide	21-Jun-44	54	7	102.1	13.0	-	115.1	4,262.96​	88.71​
Berlin/Potsdam	21-Jun-44	20	0	31.5	23.5	-	55.0	5,500.00​	57.27​
Berlin	06-Aug-44	4	0	10.0	-	-	10.0	5,000.00​	100.00​
Berlin/Marienfelde	06-Aug-44	82	4	151.5	42.5	-	194.0	4,731.71​	78.09​
Berlin/Niederschoneweide	06-Aug-44	45	2	73.0	35.0	-	108.0	4,800.00​	67.59​
Berlin	12-Sep-44	13	0	32.5	-	-	32.5	5,000.00​	100.00​
Berlin/Spandau	06-Oct-44	140	1	224.5	57.6	-	282.1	4,030.00​	79.58​
Berlin/Spandau	06-Oct-44	69	0	105.0	59.2	-	164.2	4,759.42​	63.95​
Berlin/Spandau	06-Oct-44	68	0	83.5	27.5	51.3	162.3	4,773.53​	51.45​
Berlin/Tegel-Altmarkisches	06-Oct-44	89	2	166.5	46.0	-	212.5	4,775.28​	78.35​
Berlin	05-Dec-44	13	0	19.5	13.0	-	32.5	5,000.00​	60.00​
Berlin	05-Dec-44	214	3	505.3	-	9.1	514.4	4,807.48​	98.23​
Berlin/Tegel-Rheinmetal	05-Dec-44	174	9	257.0	171.2	-	428.2	4,921.84​	60.02​
Berlin	03-Feb-45	1	0	1.5	1.0	-	2.5	5,000.00​	60.00​
Berlin	03-Feb-45	215	2	389.5	144.0	-	533.5	4,962.79​	73.01​
Berlin	03-Feb-45	717	24	1,639.3	106.6	-	1,745.9	4,870.01​	93.89​
Berlin/Alexander Platz	26-Feb-45	424	2	623.7	607.5	-	1,231.2	5,807.55​	50.66​
Berlin/North	26-Feb-45	291	2	402.7	249.1	-	651.8	4,479.73​	61.78​
Berlin/Schlesischer	26-Feb-45	374	2	538.3	356.7	-	895.0	4,786.10​	60.15​
Berlin	18-Mar-45	34	1	20.2	67.7	-	87.9	5,170.59​	22.98​
Berlin/Henningsdorf	18-Mar-45	75	0	92.5	52.2	-	144.7	3,858.67​	63.93​
Berlin/North Goods	18-Mar-45	498	8	734.9	688.8	-	1,423.7	5,717.67​	51.62​
Berlin/Schlesischer	18-Mar-45	25	0	14.3	48.0	-	62.3	4,984.00​	22.95​
Berlin/Schlesischer	18-Mar-45	362	4	426.8	493.0	-	919.8	5,081.77​	46.40​
Berlin/Tegel-Rheinmetal	18-Mar-45	107	0	102.0	104.7	-	206.7	3,863.55​	49.35​
Berlin/Tegel-Rheinmetal	18-Mar-45	118	1	153.8	80.3	-	234.1	3,967.80​	65.70​
Berlin/Spandau	28-Mar-45	403	2	694.2	344.5	-	1,038.7	5,154.84​	66.83​
Totals	All	9605​	331​	14079​	8978​	60.4​	23117.4​	4,813.62​	60.90​

As for Lancasters carrying 14,000 pounds of bombs to Berlin during the Battle of Berlin the groups determined the bomb loads rather then HQ Bomber Command and it is hard even for a Lancaster to carry 14,000 pounds when half the load on average is incendiary. The by aircraft types are despatched from Bomber Command War Diaries, add 50 Stirlings on 22 November 1943, the average load calculated from attacking sorties. Note pathfinders often returned with some bombs on board, mostly markers. The 21 January 1944 raid was a diversion. Battle of Berlin 16 main force raids, plus 1 diversion that used Lancasters, another 15 Mosquito only raid nights.

Date	Atk	Lost	H.E.	I.B.	Total	average	%HE	Mosquito	Halifax	Lancaster
18-Nov-43​	402	9	894.0	890.8	1,784.8	8,879.76​	50.09​	4​	0​	440​
22-Nov-43​	670	26	1,268.5	1,491.7	2,760.2	8,239.52​	45.96​	11​	234​	469​
23-Nov-43​	322	20	795.4	699.2	1,494.6	9,283.48​	53.22​	8​	10​	365​
26-Nov-43​	407	28	961.5	803.2	1,764.7	8,671.61​	54.49​	7​	0​	443​
02-Dec-43​	401	40	987.6	900.3	1,887.9	9,415.82​	52.31​	18​	15​	425​
16-Dec-43​	450	25	1,061.1	971.7	2,032.8	9,034.67​	52.20​	10​	0​	483​
23-Dec-43​	338	15	795.1	647.4	1,442.4	8,535.20​	55.12​	8​	7​	364​
29-Dec-43​	656	20	1,231.0	1,361.2	2,592.2	7,903.17​	47.49​	3​	252​	457​
01-Jan-44​	386	28	864.4	704.0	1,568.4	8,126.67​	55.11​	0​	0​	421​
02-Jan-44​	311	27	737.5	512.8	1,250.4	8,040.95​	58.98​	12​	9​	362​
20-Jan-44​	679	35	1,303.7	1,385.0	2,688.7	7,919.51​	48.49​	10​	264​	495​
21-Jan-44​	31	1	86.2	1.6	87.8	5,665.03​	98.21​	12​	0​	22​
27-Jan-44​	481	33	1,195.0	776.7	1,971.8	8,198.59​	60.61​	15​	0​	515​
28-Jan-44​	596	46	1,215.9	972.6	2,188.5	7,343.89​	55.56​	4​	241​	432​
30-Jan-44​	489	33	1,196.6	998.9	2,195.5	8,979.70​	54.50​	12​	82​	440​
15-Feb-44​	806	43	1,377.6	1,582.1	2,959.7	7,344.20​	46.55​	16​	314​	561​
24-Mar-44​	726	72	1,198.0	1,594.3	2,792.3	7,692.21​	42.90​	18​	216​	577​
Totals	8,151	501	17,169	16,294	33,463	8,210.72​	51.31​	168	1,644	7,271

Loss rate 6.14% of attacking sorties. Note the USAAF HE tonnage in comparison to Bomber Command.

 

[wuzak]

Note pathfinders often returned with some bombs on board, mostly markers.

The markers were either 250lb TI or 1,000lb TI.

Only 1 1,000lb TI could be carried, except late in the war when a twin carrier was developed for the 1,000lb TI to be used in Mosquitoes with a bulged bomb bay.

4 x 250lb TIs could be carried.