8th Air Force use of Mosquitoes

Shortround6 · Jul 21, 2011

wuzak said:
Surely the question is "can the light/medium bombers inflict the required damage"?

btw, Mosquito could carry 3000lb from 1943 (4 x 500lb in bomb bay + 2 x 500lb on wing).

However, with the 2000lb bomb load I would figure the Mosquito would need to be 2 - 3 times more accurate than the 8th AF B-17s. That is, would need 40-60% of their bombs to fall within 1000ft of the aiming point.

That may have been the question that should have been asked but until operational research could come up with answers gross tonnage was the easy way out. The other problem with trying to use Mosquitos (or A-20s or other small bombers) is that it became apparent that 500lbs were not always the bomb of choice. The ability of the smaller bombers to use 1000lb and 2000lb bombs were more limited and their ability to use Incendiaries was even more limited. The B-17 was often limited more by the volume of it's bomb bay rather than the weight it could lift and some of the smaller bombers were certainly no better.
Under wing loads are going to have a bigger impact on speed and range than the same load carried internally.

davebender · Jul 22, 2011

January 1944. Production date for aircraft.
4,000 lb internal bomb load. Bonus points if this can be 4 x 1,000 lb bombs.
500 miles. Minimum combat radius with 4,000 lb bomb load. More is better.
250 mph. Minimum cruise speed with 4,000 lb bomb load and 500 mile combat radius. Faster is better as we want to minimize time over enemy airspace.
10,000 feet. Cruising altitude. The actual attack may be conducted from even lower. Perhaps in a shallow dive to increase speed.
Bonus points for cockpit armor and overall aircraft ruggedness. Ground fire is an occupational hazzard for light bombers.

Can January 1944 versions of the A-26 and Mosquito meet or exceed these mission requirements?

wuzak · Jul 22, 2011

davebender said:
January 1944. Production date for aircraft.
4,000 lb internal bomb load. Bonus points if this can be 4 x 1,000 lb bombs.

Both can carry a 4000lb bomb load. Not sure if A-26 can carry 4 x 1000lb, but Mosquito can't. Mossie may be able to carry 3 x 1000lb bombs. Mosquito can carry 1 x 4000lb HC or MC bomb, not sure if A-26 can.

davebender said:
January 1944. Production date for aircraft.

Yes to Mosquito. BIX in production in early 1943 with two stage Merlins, PRXVI from late 1943, and BXVI from early 1944. Very possible to get BXVI in production earlier if PR, NF and FB don't have priority.

A-26 is in production later, but may have been possible sooner without delays and production requirements (ie not stopping production for the changeover).

davebender said:
500 miles. Minimum combat radius with 4,000 lb bomb load. More is better.

Mossie (BXVI): 1500 miles range with 4000lb bomb. Not sure how that equates to combat radius.

A-26: 1400 miles. Doesn't say if that was with internal or full bomb load.

davebender said:
250 mph. Minimum cruise speed with 4,000 lb bomb load and 500 mile combat radius. Faster is better as we want to minimize time over enemy airspace.

Not a problem for a Mossie. Think 330-350mph for a BXVI.

A-26 cruising speed is 284mph. Max speed is 355mph at 15,000ft, compared with Mossie BXVI max of 415mph at 28,000ft.

davebender said:
10,000 feet. Cruising altitude. The actual attack may be conducted from even lower. Perhaps in a shallow dive to increase speed.

10,000ft is not a good number, I believe. Not high and not low altitude. Mosquitoes could cruise at over 25,000ft with the 4000lb bomb load. A-26 is shown as having a cieling of 22,000ft! But, if we want a higher altitude we can opt for a two stage R-2800, like those fitted to the F6F and F4U.

A-26 is faster at sea level, IIRC. So better for low level ops, though you can swap out your 1710hp 76/77 Merlins in your Mosquito BXVI for 2000hp Merlin 66s if low level ops is your goal.

wuzak · Jul 22, 2011

Shortround6 said:
That may have been the question that should have been asked but until operational research could come up with answers gross tonnage was the easy way out. The other problem with trying to use Mosquitos (or A-20s or other small bombers) is that it became apparent that 500lbs were not always the bomb of choice. The ability of the smaller bombers to use 1000lb and 2000lb bombs were more limited and their ability to use Incendiaries was even more limited. The B-17 was often limited more by the volume of it's bomb bay rather than the weight it could lift and some of the smaller bombers were certainly no better.
Under wing loads are going to have a bigger impact on speed and range than the same load carried internally.

As I said before, I think the early Mossies were capable of carry 2 x 1000lb MC bombs internally, but I can't confirm that. 2 x 1600lb SAP bombs shouldn't be a problem, though conversion to a British style tail (where the tail is round and no bigger in diameter than the body) may be needed.

A single 2000lb bomb could possibly be carried, but would probably require a slight bulge (obviosuly not as big as for the 4000lb bomb) in the bomb bay doors.

FWIW I don't think that a B-17 could carry a 4000lb bomb internally.

Incendiaries could be packed in the Mossie's bomb bay if it were carrying 2 x 100lb bombs - because ther would be plenty of space at the rear of the bomb compartment.

davebender · Jul 22, 2011

Mossie (BXVI): 1500 miles range with 4000lb bomb. Not sure how that equates to combat radius.

Most sources I have read consider combat radius to be roughly one third of total range. That allows time to form up and provides some fuel to be burned in combat maneuvers at WEP.

Max speed matters only after you have dropped your bombs. Cruise speed with payload is more important for a bomber.

10,000ft is not a good number, I believe. Not high and not low altitude

It's all about accuracy vs survivability. Let's look at some estimates.

B-17G bombing from high altitude.
32% of bombs within a 610 meter circle.
Unacceptable for a light bomber. If you are going to carpet bomb an entire city then you want heavy bombers.

Ju-88A or Me-410A Dive Bomber.
50% of bombs within a 50 meter circle.
State of the art for WWII era bombing accuracy. Unfortunately neither the Mosquito nor the A-26 can dive bomb.

German level bomber. 3,000 meter altitude. Lotfe 7D stabilized bomb sight.
50% of bombs within a 91 meter circle. I assume the Norden bomb sight can deliver similiar results.
Good enough to hit a major factory complex. 3,000 meters / 10,000 feet will keep you above 3.7cm light flak. You've got enough altitude for evasive action vs enemy fighter aircraft. You've also got enough altitude to attack in a shallow dive to increase speed, thereby minimizing time over a heavily defended target.

Shortround6 · Jul 22, 2011

wuzak said:
As I said before, I think the early Mossies were capable of carry 2 x 1000lb MC bombs internally, but I can't confirm that. 2 x 1600lb SAP bombs shouldn't be a problem, though conversion to a British style tail (where the tail is round and no bigger in diameter than the body) may be needed.

I ask again, does anybody have a bomb rack chart or mission reports with such a load?

1600lb AP bombs are semi useless to a Mosquito (and most other medium level bombers) While the weight looks impressive they need to be dropped from altitude in order to penetrate (they need the speed) leading to low accuracy and for unarmored targets (anything less than a heavy cruiser) they carry much less explosive than a 1000lb bomb. The 1600lb MK 1 Bomb (Navy) carried 209lbs of Ammonium nitrate. while a 1000lb sap bomb carried about 300lbs and a 1000lb GP bomb could carry about 500lb or more. The 1600lb bomb was 14in in diameter but a 1000lb GP bomb was 18.6in dia.

A B-17 could carry a pair of 2000lb (23in dia?)internally but could not carry 4000lb bombs inside. The incendiaries should be on racks and not just stuffed in and held by the closed bay doors (while the British did use this method on early bombers it was going out of service in later years). It may only work with light incendiaries in any case. B-17s often used 65-100lb incendiaries or cluster incendiaries that had to be held on racks.

Bomb loads also had to meet CG requirements and the Mosquito took awhile to get the 4000lb (30in dia?) cookie right or at least acceptable.

Milosh · Jul 22, 2011

davebender said:
Most sources I have read consider combat radius to be roughly one third of total range. That allows time to form up and provides some fuel to be burned in combat maneuvers at WEP.

Max speed matters only after you have dropped your bombs. Cruise speed with payload is more important for a bomber.

It's all about accuracy vs survivability. Let's look at some estimates.

B-17G bombing from high altitude.
32% of bombs within a 610 meter circle.
Unacceptable for a light bomber. If you are going to carpet bomb an entire city then you want heavy bombers.

Ju-88A or Me-410A Dive Bomber.
50% of bombs within a 50 meter circle.
State of the art for WWII era bombing accuracy. Unfortunately neither the Mosquito nor the A-26 can dive bomb.

German level bomber. 3,000 meter altitude. Lotfe 7D stabilized bomb sight.
50% of bombs within a 91 meter circle. I assume the Norden bomb sight can deliver similiar results.
Good enough to hit a major factory complex. 3,000 meters / 10,000 feet will keep you above 3.7cm light flak. You've got enough altitude for evasive action vs enemy fighter aircraft. You've also got enough altitude to attack in a shallow dive to increase speed, thereby minimizing time over a heavily defended target.

Are those combat stats or stats from a test range?

davebender · Jul 22, 2011

Bombing accuracy of B-17 and B-24 groups in WW2

mhuxt · Jul 22, 2011

From the site above: "The "AIMING POINT" for R.A.F. bombers would be the entire city."

That is, in a word, bullsh*t, and is another thread hijack.

davebender · Jul 22, 2011

This discussion is about American bombers (i.e. 8th Air Force). Are you saying the B-17 and B-24 data in the link is wrong?

Glider · Jul 22, 2011

Unfortunately the following quotation from the "United States Strategic
Bombing Survey. Summary Report. Washington Sept 1945"
gives in retrospect a far different assessment of "precision
bombing" by the USAAF than has been generally publicised :

Conventionally the air forces designated as "the target area" a circle having a
radius of 1000 feet around the aiming point of attack. While accuracy improved
during the war, Survey studies show that, in the over-all, only about 20% of the
bombs aimed at precision targets fell within this target area. A peak accuracy of
70% was reached for the month of February 1945. These are important facts
for the reader to keep in mind, especially when considering the tonnages of bombs
delivered by the air forces. Of necessity a far larger tonnage was carried
than hit German installations.

From this you can see that the 30% figure is well off. Some of the comments in the page you quote give concern. The Aiming point for the RAF wasn't the entire city, they were normally the markers laid down by the Pathfinders.

The Link to the whole document is as follows NOTE Best viewed with screen realization 1024 x 768,

mhuxt · Jul 22, 2011

davebender said:
This discussion is about American bombers (i.e. 8th Air Force). Are you saying the B-17 and B-24 data in the link is wrong?

This discussion, as you can tell from its title, is about Mosquitos, specifically, their hypothetical use as the 8th Air Force's main bomber.

If I wanted to say the data was wrong, I'd say something like, "that data is wrong."

As it happens, I've been looking for what I believe is the original report used in that site. It's here:

Report on bombing accuracy, Eighth Air Force, 1 September 1944 to 31 December 1944. :: World War II Operational Documents

I have other reports on 8th AF accuracy statistics, but as noted, that would be another thread hijack, away from "8th Air Force use of Mosquitoes."

wuzak · Jul 22, 2011

Shortround6 said:
I ask again, does anybody have a bomb rack chart or mission reports with such a load?

1600lb AP bombs are semi useless to a Mosquito (and most other medium level bombers) While the weight looks impressive they need to be dropped from altitude in order to penetrate (they need the speed) leading to low accuracy and for unarmored targets (anything less than a heavy cruiser) they carry much less explosive than a 1000lb bomb. The 1600lb MK 1 Bomb (Navy) carried 209lbs of Ammonium nitrate. while a 1000lb sap bomb carried about 300lbs and a 1000lb GP bomb could carry about 500lb or more. The 1600lb bomb was 14in in diameter but a 1000lb GP bomb was 18.6in dia.

A B-17 could carry a pair of 2000lb (23in dia?)internally but could not carry 4000lb bombs inside. The incendiaries should be on racks and not just stuffed in and held by the closed bay doors (while the British did use this method on early bombers it was going out of service in later years). It may only work with light incendiaries in any case. B-17s often used 65-100lb incendiaries or cluster incendiaries that had to be held on racks.

Bomb loads also had to meet CG requirements and the Mosquito took awhile to get the 4000lb (30in dia?) cookie right or at least acceptable.

I don't think Mosquitoes used bombs other than the 250lb GP/MC, the 500lb GP/MC, the 4000lb HC or the 4000lb MC bombs operationally. But they were tested with other weapons. I am trying to find out what Mossies could carry.

The British 1000lb MC bomb was 17.75in in diameter and 52.5in long. The older 1000 GP was also 52.5in long, 16.15in in diameter. We know that the 4000lb HC "cookie" was 30in in diameter, and was not the full width of the bomb bay, and 110in long, and also not the full length of the bomb bay. If they couldn't carry two 1000lb MC/GP bombs side by side it is likely they could have carried them end for end. The British 500lb GP bomb was 12.9in in diameter and 70.6in long, or 55.6in long when shortened for use in the Mosquito. If they carried two 1000lb MC bombs end to end it would likely affect CoG very little (as it would be very similar to 4 x 500lb bombs).

The 1600lb AN-Mk1 SAP was one of the most used bombs by the 8th AF.

The US 2000lb GP AN-M66A1 bomb was 92.83in long and 31.6in across the fins.

B-17s could carry a maximum of 4 x 2000lb bombs, 6 x 1600lb SAP bombs or 6 x 1000lb bombs.

How the RAF carried incendiaries:

Lancaster bomb bay

The 4000lb "cookie" caused the centre of gravity to be too far back on the converted BIVs. The two stage Merlins were longer and heavier, which moved the CoG forward, and made carrying the cookie more acceptable.

wuzak · Jul 22, 2011

The site where I have got data for British bombs in the past appears to be dead.

http://www.wwiiequipment.com/

mhuxt · Jul 23, 2011

Sharp Bowyer's "Mosquito" lists the later 8 Group Oslo raid (not the early 2 Group spectacular in 1942) as having used Mossies with 2x500 and 1x1000 lbs. Wasn't a regular load though, as their table of bombs dropped in the Appendices says, IIRC, 14 of the 1,000-lbers were dropped in all of '44. The 1,000 lb Target Indicators were a regular load according to the same table, I don't have dimensions offhand.

wuzak · Jul 23, 2011

Found this, which gives the bomb load of a BIV as:

Up to 2,000 lb max, all internal:
2 × 1,000 lb
1 × 1,000 lb + 2 × 500 or 2 × 250 lb
4 × 500 lb
Specialy modified bombers could carry 1 × 4,000 lb "cookie " bomb

Though there are no sources listed.

Hop · Jul 23, 2011

The 1,000 lb Target Indicators were a regular load according to the same table, I don't have dimensions offhand.

Body length 53.6 inch, tail 20, total 73.6
Body diameter 17
Tail width 17.4

Shortround6 · Jul 23, 2011

wuzak said:
I don't think Mosquitoes used bombs other than the 250lb GP/MC, the 500lb GP/MC, the 4000lb HC or the 4000lb MC bombs operationally. But they were tested with other weapons. I am trying to find out what Mossies could carry.

The British 1000lb MC bomb was 17.75in in diameter and 52.5in long. The older 1000 GP was also 52.5in long, 16.15in in diameter. We know that the 4000lb HC "cookie" was 30in in diameter, and was not the full width of the bomb bay, and 110in long, and also not the full length of the bomb bay. If they couldn't carry two 1000lb MC/GP bombs side by side it is likely they could have carried them end for end. The British 500lb GP bomb was 12.9in in diameter and 70.6in long, or 55.6in long when shortened for use in the Mosquito. If they carried two 1000lb MC bombs end to end it would likely affect CoG very little (as it would be very similar to 4 x 500lb bombs).

The ability to carry the 1000lb bombs end for end may depend on the bomb rack set up. the room may be there. The Mosquito bomb bay may still not offer the flexibility of the B-17 bomb bay (and that had restrictions of it's own).

wuzak said:
The 1600lb AN-Mk1 SAP was one of the most used bombs by the 8th AF.

Do you have source for this? While the 303BG is not the 8th AF I have looked at over 60 missions ( out of over 300) and found no mention of 1600lb bombs. this bomb has very little use for attacking anything but big ships. It is usually listed as an "AP" bomb and not "SAP" and carries less explosive than a 500lb GP bomb.

wuzak said:
B-17s could carry a maximum of 4 x 2000lb bombs, 6 x 1600lb SAP bombs or 6 x 1000lb bombs.

Most B-17s could only carry four 2000lb bombs if they carried two of them externally. They could carry eight 1600lb of 1000lbs internally plus two externally but not very far. There is a B-17 manual on this site and page 53(?) shows the bomb rack chart for B-17Fs and Gs. Rack limits (barring typos or misprints) seem to limit the B-17 to loads of twenty four 100lb bombs, sixteen 300lb bombs, twelve 500lb bombs. Of course combinations could be carried but just because there is excess weight or volume available doesn't mean you can stick what ever you want in it.

wuzak said:
How the RAF carried incendiaries:

The 4000lb "cookie" caused the centre of gravity to be too far back on the converted BIVs. The two stage Merlins were longer and heavier, which moved the CoG forward, and made carrying the cookie more acceptable.

Those incendiaries are in bundles and attached to racks and/or release mechanisms are they not? I guess it depends on which incendiaries are used (some were much more "bomb like") and if the Mosquito's (or other light/medium bomber) bombay had the "flexibility of the Lancaster's. The "roof" of the Lancaster bay seems to have been a grid that various attachments could be hooked to or put through holes from above by crewmen with access from above. Other bombers may not have had the same access or adaptability.

Milosh · Jul 23, 2011

Number of Bombs Dropped in Theaters vs Germany, By Type of Bomb: 1943 to Aug 1945

Army Air Forces in World War II

Shortround6 · Jul 23, 2011

Thank you.

8th Air Force use of Mosquitoes

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