Jump to content

What's the reasons for using vision ports instead of periscopes?


curious1234
 Share

Recommended Posts

I don't know anything about engineering, but at a quick glance with my untrained eye, vision ports just seems vastly inferior to using periscopes as vision devices.

They both create a weaksport in the armor, the armored glass can shatter (and injure the crew) if hit by even small anti-tank weapons like the Soviet anti-tank rifle, but it's not just the actual vision port itself but any hole in an armor plate makes the whole armor plate weaker. (I think?)

They look vastly more complex than a periscope. Look at the driver's vision port on the Tiger 1 for example, there are many groves and holes that need to be the made for the mounting of the armor blocks and the mechanism on the inside around the vision port, then a locking mechanism for the armored glass, then a mechanism so the driver can close the vision port. This looks pretty complicated.

A periscope can also be made to be rotatable so unlike a vision port you can look through it at almost any angle.

Edited by curious1234
Link to comment
Share on other sites

On 11/20/2021 at 3:10 PM, shep854 said:

The same discussion is underway regarding periscopes and cameras.

Cameras are better. How would you do image processing on an analog image?

Also vastly reduces perception time and even more vastly increases target discrimination capability.

Link to comment
Share on other sites

A good zoom camera is a fine thing. But there is no substitute for two human eyes. Wherever possible, please combine both.

And these glass blocks have always irritated me. Both in the BTR-152 and in the M60, for example. Very strange to look through there. 

Link to comment
Share on other sites

45 minutes ago, Stefan Kotsch said:

A good zoom camera is a fine thing. But there is no substitute for two human eyes. Wherever possible, please combine both.

And these glass blocks have always irritated me. Both in the BTR-152 and in the M60, for example. Very strange to look through there. 

You're talking about the cupola vision blocks on the M60?  Yes, quite hard to see out.  The way they angled, plus the ammo chute making it quite difficult to get your eyes up to those vision blocks, made it quite difficult for the TC to maintain situational awareness while buttoned up.

Link to comment
Share on other sites

25 minutes ago, DKTanker said:

You're talking about the cupola vision blocks on the M60?  Yes, quite hard to see out.  The way they angled, plus the ammo chute making it quite difficult to get your eyes up to those vision blocks, made it quite difficult for the TC to maintain situational awareness while buttoned up.

What's the industry standard for forehead size?

Link to comment
Share on other sites

On 11/17/2021 at 1:06 PM, curious1234 said:

They look vastly more complex than a periscope. Look at the driver's vision port on the Tiger 1 for example, there are many groves and holes that need to be the made for the mounting of the armor blocks and the mechanism on the inside around the vision port, then a locking mechanism for the armored glass, then a mechanism so the driver can close the vision port. This looks pretty complicated.

 

Production bottlenecks. At the time it was probably easier to make than periscopes. No mirrors, prisms just a hole, a block of glass and a block of steel on a hinge. 

Link to comment
Share on other sites

15 hours ago, Markus Becker said:

Production bottlenecks. At the time it was probably easier to make than periscopes. No mirrors, prisms just a hole, a block of glass and a block of steel on a hinge. 

Keep in mind that there is no structural difference between a block of glass and a "prism". They are one and the same. A glass block, or rather, glass slab (block with parallel sides), can be inclined to be used as a refractive periscope, like the vision blocks on the American "vision cupola". By eliminating a direct path from the observer's eyes to the outside of the tank, the need for stuff like ballistic shields with eye-slits is mostly eliminated, which actually simplifies production. Also, inclining the glass block also allows it to deflect bullets and fragments much more easily, which also helps protect the observer. 

I daresay that the only form of vision port with any modicum of merit in terms of ease of production is the primitive vision slit. If it's just a narrow cut in the armour plate, it costs practically nothing other than a bit of time. But the drawbacks in field of vision and eye protection were overwhelming, and were identified almost immediately once tanks began to be used in combat.  

Edited by Interlinked
Link to comment
Share on other sites

Main advantage of vision block is simplicity. Depends on exact design some could be easier to change if needed. You can have more spare vision blocks than periscopes or just periscope heads. Vision blocks need less space inside. I think, in theory, those could be also a less vulnerable to blast than some periscopes. WWII periscopes could be pushed inside by blast, with all consequences for crew on trajectory. Also, rotary periscopes, even if not forced in, can also cause injuries by rapid movement when subjected to blast.
 

Cons are well known. Not best awareness provided, substandard protection. On second topic check Vulnerability evaluation of the M48 tank, and cupolas M1 and M13, against small arms attack.

 

There is nice 4-part article about different commander's vision solutions (not only cupolas) by Stefan, in German.

 

 

 

Link to comment
Share on other sites

2 hours ago, Przezdzieblo said:

Main advantage of vision block is simplicity. Depends on exact design some could be easier to change if needed. You can have more spare vision blocks than periscopes or just periscope heads. Vision blocks need less space inside. I think, in theory, those could be also a less vulnerable to blast than some periscopes. WWII periscopes could be pushed inside by blast, with all consequences for crew on trajectory. Also, rotary periscopes, even if not forced in, can also cause injuries by rapid movement when subjected to blast.
 

Cons are well known. Not best awareness provided, substandard protection. On second topic check Vulnerability evaluation of the M48 tank, and cupolas M1 and M13, against small arms attack.

 

There is nice 4-part article about different commander's vision solutions (not only cupolas) by Stefan, in German.

 

 

 

Those articles look like gold mines!  Google Translate seems to do a fairly good job on the German.  I do wish the M48 photos were clearer, but that's the duplication tech of the late '50s...I'd also like to see a review of the G305 cupola riser that was used in Vietnam.

See the source image

Edited by shep854
Link to comment
Share on other sites

3 hours ago, Przezdzieblo said:

Main advantage of vision block is simplicity. Depends on exact design some could be easier to change if needed. You can have more spare vision blocks than periscopes or just periscope heads. Vision blocks need less space inside.

Perhaps vision blocks are easier to change.  My experience with vision blocks and periscopes on M60s, and M60s used both, is that periscopes were much easier to replace.  Stupidly easier to replace.  The vision blocks on M60s were held in place by a frame bolted to the armor of the cupola.  The the three driver's periscopes were held in place by two wing nuts each.  The loader's daylight periscope, interchangeable with the driver's night viewer, snapped into place.  

Interesting thing about the M1's driver periscopes, mirrors.  What you see externally is a glass block however, on the inside the driver has adjustable mirrors.  Not to see up or down, which is rather limited, but to account for the different size of the drivers and driver positions.

Link to comment
Share on other sites

That could just be poor design. WWII designed British Periscops and Direct Vision blocks were easily cahnaged. Both with hinged covers/catches or a swinging bolt/wingnut affair. 

With the drivers's direct vision block on the Humber you have an easy, direct view of the front you can see.
You can open the hatch (not big enough to get out of mind) and directly view,
close it down partly to see directly in front of you,
close it down entirely to have a front view slot protected by a large thick glass block
And close a cover over the glass block to have slots to look out of. 

The dingo had a similar arrangement. Both are not too hard to drive looking out of the front direct vision port. 

My Ferret which I've driven both closed down AND with periscopes (thousands of miles on Georgia/Atlanta roads), direct vision with the hatches open is far easier as you have more side vision. 

Direct vision is more conducive to higher speeds and not bumping into things. 

Edited by rmgill
Link to comment
Share on other sites

Oh and by all means the direct vision blocks are a weak point over periscopes, the armored slots/glass blocks would be fine against small bullet splash, but the glass blocks aren't going to do great against larger caliber stuff. Conversely the shift in view from one to the other can matter somewhat on being oriented especially when rapidly changing modes. 

It's really what comes down to desired protection level vs crewman visibility. Same for the big armored glass plates on some armored cars vs hatches and periscopes. More closed down and glassed in can help with crew comfort.

Oh, having an approach march screen is always nice. Driving with your face in the wind in near freezing or freezing weather sucks donkey balls. 

Link to comment
Share on other sites

That's right, the Mk4 periscope was developed by the Polish engineer Rudolf Gundlach.

For lightly armored vehicles, these vision ports are certainly pretty good. The armor doesn't hold up much more than the vision ports. In battle tanks, however, there are ballistic weak points.

Link to comment
Share on other sites

On 11/22/2021 at 2:08 PM, Mighty_Zuk said:

What's the industry standard for forehead size?

A serious question?

There will be anthropometric data, design target would be 95th percentile, and should include a helmet.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
×
  • Create New...