The Legendary Avro 6 Bomb Carrier for the Mosquito (1 Viewer)

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wuzak

Captain
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Jun 5, 2011
Hobart Tasmania
For many years I have seen rumours and descriptions of a bomb carrier for the Mosquito which could carry 6 250lb or 6 500lb stores, usually associated with Avro.

And here it is:

Twin 1000lb Carrier 800.JPG



Well, actually it is not. This picture is from a file in the National Archives of the UK, AIR 14/2707 Mosquito Carriers - Special Types.

It is, in fact, two standard Avro 250lb/1000lb bomb carriers attached to a modified Mosquito 4000lb carrier which enables a bulged bomb bay Mosquito to carry 2 x 1000lb Target Indicators (TI) or 2 x 1000lb MC/GP bombs. These carriers were developed originally by a couple of squadrons in 5 Group and 8 Group to use 1000lb stores - principally the 1000lb TI. There were two main TIs during the war - 250lb and 1000lb, but no 500lb TI. Correspondance relating to these carriers started in mid 1944 and continued into late 1944/early 1945.

A few months earlier a 4000lb carrier was adapted to carry a single 1000lb TI (same size as 1000lb MC bomb) in a standard Mosquito bomb bay. Some trimming of the bomb bay door stiffeners was required to give adequate clearance. This still only amounted to a 1000lb load.

In early-mid 1944 there were moves made to better utilise the bulged bomb bay in aircraft performing target marking. It was deemed poor economics to send a Mosquito with the larger bomb bay to target carrying a load of 4 x 250lb TIs. A solution that was tried was the adaptation of a bomb beam from a Vickers Wellington. The description is of a double beam (presumably that means it could hang bombs on both sides) which was shortened, with additional stiffeners.

The Wellington bomb bay
Wellington_bomb_bay_India_WWII_IWM_CF_135.jpg


A meeting was held at RAF Upton in June 1944 to inspect the installation of a modified Wellington bomb beam fitted to a Mosquito. The meeting notes show that there were some minor revisions to be done to the installation. The installation achieved the goal of carrying 8 x 250lb TIs. Other loads were discussed:

8 x 500lb MC bombs - de Havillands thought that the all-up weight would be too high and the CoG too far rearwards for this to be viable (this may be for a B.IV with bulged bomb bay, it isn't clear).
4 x 500lb + 4 x 250lb bombs - which was to be forwarded to de Havillands for their consideration.

The last page in the file was a letter from AVM D. Bennett, 8 Group, titled "Increased Stowage for TIs in Mosquito Aircraft" and dated 27 April 1944. The two options suggested were the Wellington beam option, as above, and the development of a new type carrier which could only carry 6 250lbb TIs but would require less modification to the aircraft. There is no indication as to whether the second option went any further than that, but that could be the basis for the "Avro Carrier".
 
Another document I have recently acquired is about trials of the Norden bomb sight in the Mosquito during July 1944.

The conclusions were that the bomb sight was well made, was easy to learn how to use, but was more complicated in operation than the British Stabilized Automatic Bomb Sight (SABS).

There were tactical limitations to the use of the Norden. A bank of 18° would topple the gyro - not an issue in a B-17 and the way they were used, but not good for a type such as the Mosquito. Furthermore, in the Mosquito installation a bank of 5° would make it impossible for the bomb aimer to sight through the telescope.

It was noted that of 25 test bomb runs at 15,000ft in only 15 was it possible to aim and drop bombs due to the weather. The Norden required a long straight run up to target with little or no cloud in that time.

During the tests it was found that it was difficult to level the gyro in flight due to fluctations of the bubbles in the level gauges. It was thought that this was due to slight instability of the Mosquito, no issues having been experienced in the similarly sized P-38. The experience was that the sight would often need to be releavelled, after which the crosshairs would invariably be off target.

The Mosquito used was a B.XX, whose CoG was further aft than normal, which may have contributed to the instability experienced.

Bombing results were poor, with an average distance from target of around 500 yards.
 
Another document I have recently acquired is about trials of the Norden bomb sight in the Mosquito during July 1944.

The conclusions were that the bomb sight was well made, was easy to learn how to use, but was more complicated in operation than the British Stabilized Automatic Bomb Sight (SABS).

There were tactical limitations to the use of the Norden. A bank of 18° would topple the gyro - not an issue in a B-17 and the way they were used, but not good for a type such as the Mosquito. Furthermore, in the Mosquito installation a bank of 5° would make it impossible for the bomb aimer to sight through the telescope.

It was noted that of 25 test bomb runs at 15,000ft in only 15 was it possible to aim and drop bombs due to the weather. The Norden required a long straight run up to target with little or no cloud in that time.

During the tests it was found that it was difficult to level the gyro in flight due to fluctations of the bubbles in the level gauges. It was thought that this was due to slight instability of the Mosquito, no issues having been experienced in the similarly sized P-38. The experience was that the sight would often need to be releavelled, after which the crosshairs would invariably be off target.

The Mosquito used was a B.XX, whose CoG was further aft than normal, which may have contributed to the instability experienced.

Bombing results were poor, with an average distance from target of around 500 yards.

Did the document say what speeds they were bombing from?
 
No, it did not. Which is surprising.

You would think that would be a vital piece of information for setting up the sight.

Exactly!

I doubt you could do a bomb run faster than 150 mph. To me this is a waste of assets to fly a high altitude mission in this capacity. The only way this could have worked is with zero fighter opposition.
 
Was there a limiting speed for the Norden bombsight? Surely B-17s flew faster and bombed at a faster speed than 150mph (unless you are talking IAS)?

The planned trials for the Mosquito were to be from 25,000-30,000ft but the only ones completed were at 15,000ft. My earlier post mentioned a July date, but that was the meeting for the inpection of the sight installation. Actual bomb runs were started in late September, and the report dated November 1944.

Another thought I had was the connection between the aircraft and the bomb sight. In the B-17 he bombadier controlled the aircraft with the sight via the auto-pilot system. I doubt it was set up that way in the Mosquito, the bomb aimer having to call corrections to the pilot.

But what about the P-38? Did that have any auto-pilot system, or would it have operated in a similar manner to the Mosquito?
 
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Was there a limiting speed for the Norden bombsight? Surely B-17s flew faster and bombed at a faster speed than 150mph (unless you are talking IAS)?

The planned trials for the Mosquito were to be from 25,000-30,000ft but the only ones completed were at 15,000ft. My earlier post mentioned a July date, but that was the meeting for the inpection of the sight installation. Actual bomb runs were started in late September, and the report dated November 1944.

IIRC The normal bomb run was at about 150 indicated (maybe a bit faster)
 
I believe the droop snoot P-38s did not have an auto pilot. IIRC those mission were flown with little or no enemy opposition and at medium altitudes. Agree with your statement - using the Mosquito in this capacity would have been a waste.Lockheed P-38 Droop Snoot

Interesting that they introduced the Droop Snoot to improve accuracy but then, if I am reading that link correctly, they all drop their bombs automatically when the Droop Snoop bombadier releases his.
 
Interesting that they introduced the Droop Snoot to improve accuracy but then, if I am reading that link correctly, they all drop their bombs automatically when the Droop Snoop bombadier releases his.

Exactly, and I believe from altitudes at 20K. Later in the war that's the way the heavies did it with a bombardier in the nose and a "toggle" in each of the remaining aircraft.
 
In conversations I had with a veteran observer in Mosquitos with 627 Squadron, he told me that they dropped their TI while doing a shallow dive. I would think the speed was faster than 150.
 

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