Aldis gun sight - how did it work?

[Buffnut453]

I had the chance today to peer into an Aldis 1.8in gun sight from a Bristol Fighter.  The reticule comprised two concentric circles, one very small and the other much larger.  The latter had “100” marked next to it.

Do any experts out there know how it would be used by the pilot?  I presume the smaller circle was the aiming point but what of the larger circle and the “100” annotation?

[Tawhiri]

A couple of discussion threads from elsewhere that explain how it worked.

https://simhq.com/forum/ubbthreads.php/topics/3273924/aldis-gunsight-how-did-it-work

https://www.wingsofwar.org/forums/showthread.php?15991-SE5a-Aldis-telescopic-sight

Basically as long as you had both rings over the target, if it wasn't a deflection shot, the bullets would hit the target. Unlike a ring and bead sight, the pilot didn't have to have their eye perfectly centred behind the bead, which in turn had to be perfectly centred on the ring.

 

Edited 20 June , 2022 by Tawhiri

[MikeMeech]

6 hours ago, Buffnut453 said:

I had the chance today to peer into an Aldis 1.8in gun sight from a Bristol Fighter.  The reticule comprised two concentric circles, one very small and the other much larger.  The latter had “100” marked next to it.

Do any experts out there know how it would be used by the pilot?  I presume the smaller circle was the aiming point but what of the larger circle and the “100” annotation?

Hi

The 1917 'Text Book on Aerial Gunnery' has the following:

'British Aircraft Armament' Volume 2, by R Wallace Clarke has some drawings, on pages 130-131, which may be helpful:

Mike

[Buffnut453]

8 hours ago, Tawhiri said:

A couple of discussion threads from elsewhere that explain how it worked.

https://simhq.com/forum/ubbthreads.php/topics/3273924/aldis-gunsight-how-did-it-work

https://www.wingsofwar.org/forums/showthread.php?15991-SE5a-Aldis-telescopic-sight

Basically as long as you had both rings over the target, if it wasn't a deflection shot, the bullets would hit the target. Unlike a ring and bead sight, the pilot didn't have to have their eye perfectly centred behind the bead, which in turn had to be perfectly centred on the ring.

 

Many thanks for those links, Tawhiri.  Very helpful in describing how the sight would be used.  

[Buffnut453]

3 hours ago, MikeMeech said:

Hi

The 1917 'Text Book on Aerial Gunnery' has the following:

'British Aircraft Armament' Volume 2, by R Wallace Clarke has some drawings, on pages 130-131, which may be helpful:

Mike

 

Mike,

Many, MANY thanks for those contemporaneous details.  You might like to see the image I was able to capture showing the sight fully functioning over 100 years after it was built:

Edited 20 June , 2022 by Buffnut453