Mk1 Bombing Angle Computer

[Akubra]

Hi
Can anyone tell me about this? I would like to know what aircraft they were used with and when. Any details would be appreciated.
Cheers!
http://i119.photobucket.com/albums/o131/acubra/bac1.jpg?t=1296205540

http://i119.photobucket.com/albums/o131/acubra/bac2.jpg?t=1296205540

[682al]

I think it's a computor to work with a bombsight of the T-series when the bombsight's own computor is not installed or in use, i.e. when the sighting head alone is being used. It may also have been used when bombs of very low velocity were being used which the computor was not able to cope with.

The T series bombsights were all evolved from the wartime Mk XIV bombsight (the so called Area Sight) and were mainly just updates to allow for increased operating heights and speeds, etc.

As for use, well it has a hand written date of 1947 on it so I'd be thinking of an Avro Lincoln maybe. That said, it was probably also used in the Canberra and quite possibly the V bombers?

There may well still be posters on the Military Forum who have actually used them.

[Fareastdriver]

It must have been post WW 2 otherwise it wou;d have MPH written on it.

[Akubra]

Thanks anyway. I thought someone here might been able to place it's origin.
It's rather large at 20cm diameter and is made of aluminum. The handwritten date reads 13-7-47 with what appears to be MOD (or MOO) -7-51 written below that.
Max ground speed is 650 kts and the max altitude is 75000 ft.
I guess it was a redundancy device just in case the computer failed.

[redsetter]

There's a three-page description of the device in AP.1275D, amended to 1961, which suggests it was in service for a while. Doesn't mention aircraft types though. PM me if you want a copy.

[Tony Laven]

In late 1961 as a necessary precursor to the conversion on to Canberras I attended a Bomb-aimer’s course at the Bomber Command Bombing School (BCBS) at RAF Lindholme, near Doncaster. The Vickers Varsity, in which I had completed my Navigator Training, had a bomb bay and a bomb aiming position in a ventral pannier under the main fuselage. This could accommodate a student and instructor. The aircraft could carry twenty four 25 lb practice bombs, four each on six 'Light Series Carriers' and we used the bombing ranges at Theddlethorpe and Wainfleet in the Wash for our visual bombing practice which was carried out around 10,000 feet.

We were taught about the theory of bombing and used the hand-held Bombing Angle Computer to determine both the cross-trail angle and the bombing angle. It could be used, as suggested with the sighting head was disconnected from the T2 bombing computer. I seem to recall that our first bombing exercises used the settings from the hand held computer.

Mounted on the port side of the bomb aiming position and level with the bomb aimer's elbow, was the T2, bombing computer connected to a matching T2 Gyro-stabilised Bombsight. In outward appearance these units were little different from those used by World War II bombing crews.

The type of bomb, in this case a 25 lb practice bomb and the wind speed & direction were manually set on the face of the T2 computer. It was automatically fed with altitude and indicated airspeed from the aircraft system. The computer fed drift and bombing angle to the sight head, the drift input would rotate the sight head by drift angle plus a factor to allow for cross-trail, (any cross wind will act not only upon the plane but also upon the bomb after release, and compensation for this cross-trail must be made). The bombing angle output moved the collimator which projected a graticule, a cross of red light onto the stabilised glass. The computer then continuously calculated the trajectory of the bombs with changes in speed or aircraft attitude. The bomb aimer gave directions to the pilot to put the aircraft on the fore and aft line through the target. When the cross marker went through the target the bombs were released.

The Bombing Angle Computer was used on the Canberra, the earlier T2 series bombing computer had an effective height range up to 25,000 ft. While in the 1950s Canberra blind high-level bombing used Gee-H, at heights around 40,000ft. If the equipment became unserviceable, visual bombing had to be used. This was, of course, outside the capability of the T2 computer. The sighting head was therefore disconnected and the settings from the hand-held computer used.