8th Air Force use of Mosquitoes

[wuzak]

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

Army Air Forces in World War II

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.

Evidently I was wrong....

Still, it shows the importance of the 500lb bombs compared to the 1000lb or 2000lb bombs in USAAF thinking.

The USAAF used the 500lb bombs 5.5 times they did the 1000lb bomb. And 63 times the 2000lb bomb. They used nearly twice the number of 250lb bombs that they did with the 1000lb bomb. Looking only at GP bombs.

The Mosquito could certainly drop 500lb and 250lb bombs.

 

[wuzak]

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).

Well, the Mosquito certainly carried 4 x 500lb or 250lb bombs in 2 x 2 formation, and also a single 4000lb bomb. That would suggest the ability to change racks to suit the load.

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.

I have read the maximum load for a B-17G as being 4 x 2000lb or 6 x 1000 or 1600lb bombs internally. But the sources for that have usually been web pages, so the accuracy would be questionable. I'll find that manual later and have a look.

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.

I did have a look at the de Havilland museum's B.35 Mosquito back in 2007, but didn't get any pictures in the bomb bay. I did inside W4050's bomb bay, but it was being stripped down, and what you could see inside the bay were the fuel cells, which sat above the bomb bay.

 

[davebender]

Do we have historical accuracy data for Mosquitoes bombing from 5,000 to 10,000 feet?

Small, hand picked and specially trained units don't count. We need normal Mosquito light bomber units conducting normal (i.e. not pathfinder) missions.

 

[mhuxt]

Do we have historical accuracy data for Mosquitoes bombing from 5,000 to 10,000 feet?

No, because they didn't bomb from those altitudes.

 

[davebender]

If true then why do people think the Mosquito was such a great light bomber?

 

[wuzak]

If true then why do people think the Mosquito was such a great light bomber?

They either bombed from higher, in which case their accuracy would be no worse than other aircraft from that altitude, or from low level.

When bombing from low level they could achieve a high level of accuracy, almost 100% could be achieved.

 

[wuzak]

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

http://www.wwiiequipment.com/

Now it is working again.

 

[wuzak]

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.

My mistake, the length dimensions I quoted for the 1000lb bombs were for the body. The overall length of the GP bomb could be 86.5in or 71in and for the MC bomb 72.6in.

So the 1000lb bombs could not possibly be carried end to end in a Mosquito bomb bay.

 

[Shortround6]

If true then why do people think the Mosquito was such a great light bomber?

Because it was. It could bomb at the lower altitudes and get hits. It could bomb at high altitude and while no better than many other bombers it was no worse. Some of the high altitude raids were propaganda raids, They didn't expect to hit much. It had more range than most other "light" bombers. It was faster and suffered lower losses.

However it takes a might great "light" bomber to replace a "heavy" bomber on a one for one basis.

Bombing at 5000ft only works if your enemy doesn't have light AA. It is on the edge of 20mm effective range. It is well with 37-40mm range. 10,000ft is just inside the effective range of most 37-40mm guns. Please note that 37-40mm AA guns were not common in 1939-41. The certainly existed but not in the numbers they would later in the war. Tactics that worked in 1940 would near suicide in 1944.

 

[Shortround6]

My mistake, the length dimensions I quoted for the 1000lb bombs were for the body. The overall length of the GP bomb could be 86.5in or 71in and for the MC bomb 72.6in.

So the 1000lb bombs could not possibly be carried end to end in a Mosquito bomb bay.

Thank you for the correction/information. Perhaps they could be carried side by side? it might depend on the release gear, and clearance going through the doors?

Going back to the original question, the Mosquito fine a plane as it was, could not really replace B-17s on a one for one basis. The B-17 had a rather restricted bomb bay of it's own, both in length and in width with the central catwalk/beam. It could how ever carry 100lb, 250/300lb, 500lb, 600lb, 1000lb, 1600lb, and 2,000lb bombs inside. It could also carry a variety of incendiary bombs, many of the early ones were in normal looking bomb casings and mounted to standard racks and were not the clusters that came into use later. These incendiary bombs were lighter in weight than the GP bombs for their volume and reduced the bomb load due to volume/rack space considerations.

To drop an equal "tonnage" of bombs to B-17s you need at least 2 Mosquitoes and more likely 2 1/2 Mosquitoes for many targets deep in Germany. 4000lb cookies excepted and from altitude the accuracy of the 4000lb cookie was worse than normal bombs.

It is quite possible that the Mosquitoes might have been able to deliver this tonnage with fewer losses but the loss rate was unknown when production decisions had to be made and while the Mosquito with it's two man crew certainly looks attractive compared to the crew of a B-17 aircrew are not interchangeable. You may not be able to turn gunners/radio operators into pilots and navigators. In US service many Navigators/bombardiers were actually men who washed out of flight school.

 

[wuzak]

Thank you for the correction/information. Perhaps they could be carried side by side? it might depend on the release gear, and clearance going through the doors?

I think the side by side would be tight, but that reference earlier certainly says that Mosquitoes could carry two, and mhuxt quotes a load of 1 x 1000lb TI and 2 x 500lb MC bombs, the TI being the same size as the 1000lb MC bomb.

Going back to the original question, the Mosquito fine a plane as it was, could not really replace B-17s on a one for one basis. The B-17 had a rather restricted bomb bay of it's own, both in length and in width with the central catwalk/beam. It could how ever carry 100lb, 250/300lb, 500lb, 600lb, 1000lb, 1600lb, and 2,000lb bombs inside. It could also carry a variety of incendiary bombs, many of the early ones were in normal looking bomb casings and mounted to standard racks and were not the clusters that came into use later. These incendiary bombs were lighter in weight than the GP bombs for their volume and reduced the bomb load due to volume/rack space considerations.

The smaller bombs (< 250lb/300lb) were next to useless against industrial targets. But the 250lb and 500lb were the preferred bombs of the 8th AF, probably because having 10 or more bombs per bomber gives you a better chance at hitting something than just having one or two.

I don't know what arrangements the Mosquito had for attaching racks, and how many small bombs it could carry.

The B-17 could carry more types of bombs on a mission, there is little doubt. If a Mosquito had a 2000lb bomb it is likely that is all it could carry. Though it may have some space for incendiaries.

I don't know if B-17s mixed their loads much, other than to carry incendiaries along with their HE bombs.

To drop an equal "tonnage" of bombs to B-17s you need at least 2 Mosquitoes and more likely 2 1/2 Mosquitoes for many targets deep in Germany. 4000lb cookies excepted and from altitude the accuracy of the 4000lb cookie was worse than normal bombs.

It's not so much the tonnage that the Mosquito would have to compete with, but more the tonnage that could be delivered on target. It is true that the 4000lb HC bomb wasn't as accurate as normal bombs, but that wasn't such an issue for the duty it performed. An alternative to the 4000lb HC cookie was the 4000lb MC bomb - similar in design to the 500lb, except much larger, of course. It was originally designed because the cookie couldn't be used at low level because it would break apart. Mosquitoes did carry these from 1944, and used them accurately from about 30,000ft.

4000lb Medium Capcity Bomb

It is quite possible that the Mosquitoes might have been able to deliver this tonnage with fewer losses but the loss rate was unknown when production decisions had to be made and while the Mosquito with it's two man crew certainly looks attractive compared to the crew of a B-17 aircrew are not interchangeable. You may not be able to turn gunners/radio operators into pilots and navigators. In US service many Navigators/bombardiers were actually men who washed out of flight school.

It was probable that the planners never foresaw the need for bomber to release bombs en masse, rather than bombing individually - which was more accurate, but also more costly.

While what you say is correct about the gunners, navigators and bombadiers not necessarily being suitable for pilot training the B-17 did have two pilots. And a navigator and a bombadier - tasks which were combined for the Mosquito. So the gunners would be the only ones unlikely that could not be brought across.

 

[Shortround6]

From the mission reports of the 303BG it seems that on occasion the B-17s used mixed loads but it may have been just as common to use one group or squadron with one type of bomb and another group or squadron with another type of bomb on the same target. this may be because the ballistics of the different bombs needed different release points. When bombing by squadron or group all planes should use the same bombs. It may be this mixed loading that gave rise to the B-17 could only carry 4000lb to Berlin claim. They could actually carry 5,000lb of GP bombs (either ten 500lb or five 1000lb) but only about 3,000lb of incendiaries.

We still have the timing issue. The decision to equip with Mosquitoes would have had to have been made well before most of the capabilities of the Mosquito became known or were developed.

 

[wuzak]

From the mission reports of the 303BG it seems that on occasion the B-17s used mixed loads but it may have been just as common to use one group or squadron with one type of bomb and another group or squadron with another type of bomb on the same target. this may be because the ballistics of the different bombs needed different release points. When bombing by squadron or group all planes should use the same bombs. It may be this mixed loading that gave rise to the B-17 could only carry 4000lb to Berlin claim. They could actually carry 5,000lb of GP bombs (either ten 500lb or five 1000lb) but only about 3,000lb of incendiaries.

We still have the timing issue. The decision to equip with Mosquitoes would have had to have been made well before most of the capabilities of the Mosquito became known or were developed.

Mosquitoes were used on bombing missions before the 8th AF began operations. But the heavies in the USAAF and the 8th AF still believed in the self defending bomber not requiring escort - it would take another year after commencing operations before that was beaten into them.

 

[wuzak]

Just found an article in the tech forum which may shed light on the Mosquito bomb bay use.

http://www.ww2aircraft.net/forum/technical/dehavilland-mosquito-11087.html

A quick scan doesn't seem to show any text on the matter, but a picture on page 2 and the side view at the bottom of the last page (page 8.) show that the bomb racks were attached to steel cross members that were mounted in the bomb bay - which no doubt helped give some flexibility.

The end view of the bombs seem to suggest that there was room for larger diameter bombs - so it may have been possible for 2 x 1000lb in teh bay.

 

[wuzak]

Here are the pics from that pdf

 

[davebender]

You cannot bomb effectively without taking some risks. 10,000 feet is low enough for acceptable accuracy yet high enough to minimize the light flak danger.

I don't think bombing from very low altitude (say 500 feet) will work for a large aircraft formation. The Luftwaffe had warning of most air raids from acoustic detection and EW intercepts even before the bombers showed up on radar. Forewarned 3.7cm flak would murder enemy aircraft at that altitude.

 

[FLYBOYJ]

I might be a little late on this but a while back we discussed the Mosquito performing a high altitude mission in the same capacity the B-17 and B-24 accomplished. Remember that if you're bombing with a precision optical bomb sight, you are commencing you're bomb run at speeds just above cruising and I think you're probably looking at about 250 mph maximum. I know somewhere on here we posted the Mosquito's bomb door operating speed and it wasn't as high as you would expect.

In the case with a Mosquito, it would have been the same sitting duck over target as any heavy, American or British were while bombing unescorted. The advantage "would have" been after the bomb run where the Mosquito "could have" used superior speed to depart the combat area.

 

[FLYBOYJ]

Found it..

"bomb bay doors open 305 knots" = 340 mph - not bad providing you're able to accurately bomb at that speed at altitude depending on wind and other conditions.

Pilot's Notes - De Havilland Mosquito FB 6

Here's a Norden bombsight page that talks about some other bombs sights and setting speeds.

http://www.twinbeech.com/norden_bombsight.htm

 

[wuzak]

You cannot bomb effectively without taking some risks. 10,000 feet is low enough for acceptable accuracy yet high enough to minimize the light flak danger.

I don't think bombing from very low altitude (say 500 feet) will work for a large aircraft formation. The Luftwaffe had warning of most air raids from acoustic detection and EW intercepts even before the bombers showed up on radar. Forewarned 3.7cm flak would murder enemy aircraft at that altitude.

The 8th AF typically bombed from higher altitudes - around the 20,000ft mark IIRC. Lancasters also typically bombed from around 20,00ft, but this was largely because it was close to their effective ceiling.

 

[wuzak]

You cannot bomb effectively without taking some risks. 10,000 feet is low enough for acceptable accuracy yet high enough to minimize the light flak danger.

I don't think bombing from very low altitude (say 500 feet) will work for a large aircraft formation. The Luftwaffe had warning of most air raids from acoustic detection and EW intercepts even before the bombers showed up on radar. Forewarned 3.7cm flak would murder enemy aircraft at that altitude.

What about 88s?

Also, when we say low altitude, I think Mosquitoes often approached the target at 50ft, maybe rising higher at the target. The certainly did in Operation Jericho (with FBVIs) and the attack on the Zeiss optical works in Holland.

Also, at low level I think teh danger would be from 20m guns, as the larger guns may find it difficult to track a low flying object at 300mph, unless it was flying almost directly towards its position.