Russian ПП-1 type Optical Sight for 45mm AT (part 2)

[mlespaul]

See previous post for technical manual information on this .

Next interesting thing about the ПП-1 type sight is that it had a 45-mm anti-tank gun version. Same outside structure and function, but different reticle and purpose. I'm not completely certain about the types, but I have the following (pics - no I don't own these):

ПП-1 Model 1937 dated 1944 as installed on a 45-mm AT

Closeup of markings.

Slightly newer model:

Again from top looking down (as on the MG sight above):

Straight ahead (good view of the rotatable prism):

And the reticle:

This one prob looks familiar as it resembles the T-26 sight in RO, but this one is different in the grid layout. I don't know if the aiming line moves. You just raise or lower the elevation of the gun based on the intersection of lines that match the number of meters, and of course the right and left deflection values. But there is the knob/dial that inputs range settings, but I don't know if those knobs affect the reticle or just the carriage of the gun. Maybe someone out there owns one of these? Anyway, hope you enjoy.

 

[Aeneas2020]

OH NOES!! that traffic lights days are numbered

 

[[TW]Wilsonam]

And another nice find!

 

[Amizaur]

Nice !

My guess is that the cross doesn't move when you set the range. But rather the whole sigh is rotating up and down on the mounting. It's mounted exactly as needed to make this possible . And I would think that it's easier to realise rotating mounting than moving glass plates... So the way of working would be similar to periscipic sight (whole FOV moving when sight is adjusted).
IIRC then in the manual there is mentioned that you can either set the range and aim with the cross, or leave the range on zero and aim using the range scale/grid..
In general the grid can be correct only for one shell type (of shells with same ballistics)... but on close ranges (up to 500-1000m) it would work good enough I guess... and the ROF (up to 20 shots per minute) of the gun is so good that "fire and adjust" is not a problem

P.S. This is how it looks in 45mm gun manual:



Comparing it with actual photo... well...

AB 45mm gun texture (first in 2.07) was based on the manual picture, but side deflection scale was calculated to be of actual size (knowing it's +/- 50 mils), and vertical range scale was adjusted to match RO-AB shell ballistics (so it's little taller than on the photo)



On the actual photo, the angle adjustment for 2500m seem to be about 37mils (between 30 and 40), this is only a bit more than for 85mm AP (which is firead at a bit higher velocity) !! Nice long range ballistics... seem my estimate of 45mm APBC was still a bit too low (AB - 1.2, AHZ - 0.7) - IIRC I just gave it a same BC as estimated 50mm APC and that was a mistake Hard to belive so small projectile can bleed the velocity so slowly I even wondered for a while if the reticle is not for L66 gun (840m/s or something like that), but probably no - the 500m adjustment is clearly more than 5mils, so it seem to be little slower than 85mm gun... 760m/s would fit.

And, as no one mentioned:

PP-1 sight - magnification x2, field of view 20deg, diameter of the exit pupil 6mm.

It's also a panoramic sight - in the upper part there is a moving (horizontally !!! so not for range adjustment) prism that can be rotated something like 60deg left or right, giving up to 120deg (?) observation angle. In another place is again mentioned - FOV of the panoramic part - up to 240deg (so 120deg left or right). I wonder how precisely the sight could be bring back to 0deg position (for firing) after it was rotated to the side for observation If the 0deg position had some "click" that immobilised it always in exactly the same point, when you rotated back ? Or just the gunner had to very precisely set 0 on the knob/dial...? (and then lock it ?) Wonder how it was realised in periscopic sights (same for PG-1 or Rblf32) to get the sight precisely aligned again...

 

[mlespaul]

Nice !

t's also a panoramic sight - in the upper part there is a moving (horizontally !!! so not for range adjustment) prism that can be rotated something like 60deg left or right, giving up to 120deg (?) observation angle. In another place is again mentioned - FOV of the panoramic part - up to 240deg (so 120deg left or right). I wonder how precisely the sight could be bring back to 0deg position (for firing) after it was rotated to the side for observation If the 0deg position had some "click" that immobilised it always in exactly the same point, when you rotated back ? Or just the gunner had to very precisely set 0 on the knob/dial...? (and then lock it ?) Wonder how it was realised in periscopic sights (same for PG-1 or Rblf32) to get the sight precisely aligned again...

The panoramic features are discussed on the PP-1 part one thread I posted (for MG). Yeah --I don't completely understand either the efficacy of having a sight that can panoramically be adjusted for such a direct fire application....especially on the Maxim on the other PP-1 thread....Say you're aiming on a distant point....why would you need to turn the head 45 degrees, then....unless you are using it to match elevation against a set of aiming stakes or against another reference point beside you or behind you...which I could see for the 45mm application, but not for the Maxim MG....unless again...it was for setting up a enfilade/fire zone for indirect spraying of lead at a pre-determined elevation, so that you turned the prism towards the aiming stakes, then turned the elevation worm knob to elevate the setting for the aiming carriage...then ratchet up the trunion wheel to match the aiming carriage.....theories, theories....

At least I have Amizaur around to help validate things for me....and confirm how crazy optics will make you.