Norden Bombsight Developments and Attachments

KJ_Lesnick

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I've found very little information on the internet regarding the following and while I have some guesstimates and ideas as to what the systems do, I am not certain and I figure you guys would probably be able to provide a more conclusive answer.

The Automatic Gyro-Leveling Device (AGLD) / Automatic Erecting System
  • It was apparently used on early Norden's and was removed because of reliability issues
  • My assumption is that it was supposed to prevent the gyro from toppling: Am I right or wrong?
The Glide-Bombing Attatchment (GBA)
  • It was designed to allow them to climb and descend during the bombing run
  • It could somehow sense altitude and would use that to effectively adjust the gyro or something when the plane climbed or descended
I'm curious when this first became available, how quickly it reacted to climb and descent angles, and what the maximum climb and descent angles were. Frankly, I'm puzzled how banking would topple the gyro, but diving wouldn't.
 
Nobody got anything: I've searched across the web and found little more than I have now...
 
KJ_Lesnick said:
I've found very little information on the internet regarding the following and while I have some guesstimates and ideas as to what the systems do, I am not certain and I figure you guys would probably be able to provide a more conclusive answer.

The Automatic Gyro-Leveling Device (AGLD) / Automatic Erecting System
  • It was apparently used on early Norden's and was removed because of reliability issues
  • My assumption is that it was supposed to prevent the gyro from toppling: Am I right or wrong?
The Glide-Bombing Attatchment (GBA)
  • It was designed to allow them to climb and descend during the bombing run
  • It could somehow sense altitude and would use that to effectively adjust the gyro or something when the plane climbed or descended
I'm curious when this first became available, how quickly it reacted to climb and descent angles, and what the maximum climb and descent angles were. Frankly, I'm puzzled how banking would topple the gyro, but diving wouldn't.

I don't think you looked very hard.

http://www.doug-and-dusty.id.au/norden_bombsight.htm gives basic operation of a WW2 Norden sight.

http://www.twinbeech.com/norden_bombsight.htm has some nice pictures.

From Wikipedia, a good explanation of the AGLD:

"Before use, the Norden's stabilization platform had to be "righted", as it slowly drifted over time and no longer kept the sight pointed "up". This was accomplished in a time consuming process of comparing the platform's attitude to small spirit levels seen through a glass window on the front of the stabilizer. In practice, this could take as long as eight and a half minutes. This problem was made worse by the fact that the platform's range of motion was limited, and could be "tumbled" even by strong turbulence, requiring it to be reset again. This problem seriously upset the usefulness of the Norden, and led the RAF to reject it once they received examples in 1942. Some versions included a system that quickly righted the platform, but this "Automatic Gyro Leveling Device" proved to be a maintenance problem, and was removed from later examples."

Regarding the Glide Bombing Attachment, from the above links you can find that it used a bellows which is the same way used to measure altitude in a barometric altimeter. The Glide-Bombing Attachment was effectively just a sensitive altimeter which could feed data into the gunsight to correct the bomb drop for the altitude change.

Regardless of the attachments, manouvering in any meaningful way would generally abort the bomb run. The Norden gunsight was very complicated to use and very easy to cock up.

In terms of gyro toppling - typically, bank and elevation physical gimbal limits are different for each axis depending on the physical arrangement of the gyro (e.g. 100 degrees of bank but 60 degrees of elevation). Note that an aircraft entering a 2g turn would need a bank angle of 60 degrees. Its more likely they will need that than to dive at 60 degrees towards the ground.
 
Overscan,

If the limit is the same as the bank, that means the dive angle would be 18-degrees...
 

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