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jolly_magpie
02-24-2007, 10:26 PM
There must be some experten out there, I have a few questions.

Proximity fuzes. Just how small could you make one of these? The only size I can find mentioned is a 5" shell. Could they be made smaller, either in WW2 or the present day?

I got this idea during gunnery practice, seeing my rounds pass over and under my target's wings. Sigh. Sooo close, if they had proximity fuzes they would have blown the wing apart.

I am thinking maybe if it was small enough to fit into a 20mm round, you could do some real damage. Or at least compensate for my lousy gunnery!

http://upload.wikimedia.org/wikipedia/commons/thumb/b/b7/MK53_fuze.jpg/300px-MK53_fuze.jpg

Waldo.Pepper
02-24-2007, 10:57 PM
Modern example of what can be done.

http://www.youtube.com/watch?v=aq_y6kkDO7Y

jolly_magpie
02-24-2007, 11:34 PM
Hoo boy that is truly impressive. The Bofors has come a long way since my grandfather was running clips from the magazine to the gunners. The flexible options are impressive. "It slices, it dices."

So, it will fit into a 40mm shell these days?

KaleunFreddie
02-25-2007, 12:07 AM
Neat little projectile.
It seems to rely of detecting changes in it's locally created magentic field, similar to the nimrod's MAD device. Except here it probably creates it's own field via a coil. Any dense objects within proximity = poof. There is a timer to only activate the detonator within a programmed flight distance, thus avoiding false signal detonations.

I think most Western planes would be brought down with this, as they are 'high tech' planes, whereas a low tech plane would be more difficult to bring down. A few Russian high performance (but still equal to the West's planes) planes are low tech AFAIK. This''l make the difference.
http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

jolly_magpie
02-25-2007, 12:36 AM
The WW2 ones, I think this is how they worked:

The shell is fired and arms itself after a set interval. It begins sending out radio pulses. When a target is detected, it begins timing the intervals between the signal sent and received. When the interval begins to increase after the shall passes the target, the warhead is triggered.

Also, how do these electronics survive the crushing acceleration of being fired?

leitmotiv
02-25-2007, 01:00 AM
In WWII the U.S. proximity fuze rounds went down to the 76mm (3") AA gun used by the U.S.N. It was also available for the Army's 90mm AA gun, and, of course, the various U.S.N. 5" AA guns. As I recall, the Army was not allowed to use the 90mm prox shell until the Battle of the Bulge due to fear the Germans would copy it and use it with devastating effect against Allied aircraft. The U.S.N. started using prox shells in 1943, or the Battle of Santa Cruz, according to one source. They, and fire control radar, the 40mm Bofors, 20mm Oerlikons, and naval fighters, effectively made Japanese air strikes on American ships suicide missions. The only sources on prox shells I know about are Norman Friedman's U.S. NAVAL WEAPONS and John Campbell's NAVAL WEAPONS OF WORLD WAR II.

KaleunFreddie
02-25-2007, 02:01 AM
Originally posted by jolly_magpie:
Also, how do these electronics survive the crushing acceleration of being fired?

I don't think they use electronics as we know it, as the devices would never withstand the G-forces. It might be MilSpec 'electronics', but more discrete devices that can withstand these forces, like Capacitors, Coils, Resistors. These are the core of electronics, but you can do amazing things with just these devices.

For example... THE FLUX CAPACITOR http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif
http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Waldo.Pepper
02-25-2007, 04:00 PM
So, it will fit into a 40mm shell these days?

Nope smaller - 25mm

http://www.youtube.com/watch?v=miQOTO_r8Fo

http://www.youtube.com/watch?v=X_YliFd-ThQ

http://www.youtube.com/watch?v=poV4xM9Nxps

I would think that it could be made smaller as well. But then you get into the realm of too little fragmentation/explosive payload. So this may be the lowest practical limit.

Blutarski2004
02-25-2007, 04:46 PM
Originally posted by leitmotiv:
In WWII the U.S. proximity fuze rounds went down to the 76mm (3") AA gun used by the U.S.N. It was also available for the Army's 90mm AA gun, and, of course, the various U.S.N. 5" AA guns. As I recall, the Army was not allowed to use the 90mm prox shell until the Battle of the Bulge due to fear the Germans would copy it and use it with devastating effect against Allied aircraft. The U.S.N. started using prox shells in 1943, or the Battle of Santa Cruz, according to one source. They, and fire control radar, the 40mm Bofors, 20mm Oerlikons, and naval fighters, effectively made Japanese air strikes on American ships suicide missions. The only sources on prox shells I know about are Norman Friedman's U.S. NAVAL WEAPONS and John Campbell's NAVAL WEAPONS OF WORLD WAR II.


..... See also "The Deadly Fuze", Baldwin, Ralph B., Presidio Press, San Rafael, 1980.

VW-IceFire
02-25-2007, 04:52 PM
I think its just incredible that a 60 year old (or older) gun design, the 40mm Bofors, is still having ammo developed for it today. I guess you get to a certain point and the basic principles still hold true.

jolly_magpie
02-25-2007, 05:02 PM
Yeah, Bofors, what a system. It's the B-52 of guns.

25mm sounds small enough to cram into an aircraft. A lethal combo. I'll have one on each wing, please!!

The closest we have ingame is the X-4, I guess.

Lead-Brick
02-25-2007, 09:55 PM
From what I remember from another forum the WW2 fuse worked like this.

Ground based radio unit sends out a radio signal toward the target. The gunner fires at the airbourn target. the shell has a simple radio receiver, think crystal set. The radio signals bouncing off the target create dopler frequency interferance as the shell reaches a certain distance from the target. The crystal set triggers the detonator. The shells were very simple hence the worry that the Germans and Japanese would copy them.

Zeus-cat
02-25-2007, 10:13 PM
Even if the technology would have been small enough to fit into the shells of aircraft guns I doubt they would have done it. As leitmotiv has alredy posted, the Allies did not want the enemy to get this technology. One plane shot down with these shells in it would have given it away. Besides, a 20mm shell wouldn't do much damage exploding near something, it needs to hit it and then explode.

leitmotiv
02-25-2007, 10:18 PM
Zeus-cat got it right---you needed a goodly-sized projectile to kill with shrapnel.

The mini-radar in the shell itself triggered the explosion when it detected an object---the shell required no other devices to work. Known as "influence projectiles."

Waldo.Pepper
02-26-2007, 12:00 AM
Ground based radio unit sends out a radio signal toward the target. T

Sorry but this is wrong.

Also during the development period of the VT fuse the 57mm gun was used for testing purposes as it was (then) the smallest calibre that could contain the components.

Kocur_
02-26-2007, 09:25 AM
Originally posted by Waldo.Pepper:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">So, it will fit into a 40mm shell these days?

Nope smaller - 25mm
</div></BLOCKQUOTE>

Those arent really proximity fused projectiles, they have good old time fuses, just that in modern technology.
The smallest proximity fused ammo AFAIK in service are 3P (http://www.dtic.mil/ndia/2003gun/boren.pdf) projectiles for 40mm Bofors.

StellarRat
02-26-2007, 12:48 PM
Originally posted by KaleunFreddie:
I don't think they use electronics as we know it, as the devices would never withstand the G-forces. It might be MilSpec 'electronics', but more discrete devices that can withstand these forces, like Capacitors, Coils, Resistors. These are the core of electronics, but you can do amazing things with just these devices.

For example... THE FLUX CAPACITOR http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif
http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif They had at least one mini-vaccuum tube in them and battery. The whole circuit was sealed in plastic to prevent it from moving. If I knew how to post a picture I'd show you the circuit. Anyway, modern electronics CAN stand the forces of being fired, probably even better then the old electronics. Transistors (ie chips) are still small therefore very G-resistant. These mini-tubes were also used to build tiny radio transmitters that spies used in WW II.

http://www.history.navy.mil/faqs/faq96-1.htm

http://www.tubedata.org/unknown_sylvania/040408BW/shell_fuse.jpg

http://www.tubedata.org/unknown_sylvania/040408BW/a3_gg.jpg

Note how tiny these vacuum tubes are! Now a days you could easily build this circuit with transistors at home and it would be even smaller than what they are were able to do in WW II.

Blutarski2004
02-26-2007, 01:08 PM
The proximity Fuze was no big engineering feat. All they had to do was design a radar transceiver, using vacuum tube technology, that would fit into a pint milk bottle and withstand 70,000 G's acceleration.

No problem.

KaleunFreddie
02-26-2007, 01:10 PM
I did mention MilSpec, but general electronics can only withstand from 10G-20G in some cases, I haven't looked at later stuff.

Say this shell has a muzzle velocity of 600m/s, that is an acceleration over a 2m gun barrel.
If the shell takes say 0.5 secs (Slow) to do the barrel length. This is equal to 120G's... I tell you I'd would be very surprised to find a reliable microchip device (no matter how small) that can withstand this force.

No, I think it's more in the line of discrete electronic devices that are bigger and robustly constructed.
An example - A simple straight piece of wire/steel tube can be a resistor, coil, or capacitor. and you'll need to melt it to destroy it.

Of course we should not rule out chemical devices, which are just as effective.
http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

StellarRat
02-26-2007, 01:17 PM
Originally posted by KaleunFreddie:
I did mention MilSpec, but general electronics can only withstand from 10G-20G in some cases, I haven't looked at later stuff. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif I didn't say something off the shelf, I meant something you could build yourself from the individual parts. Properly secured, etc... Obviously you can't fire your I-Pod out of a cannon and expect it to work when you find it.

Sergio_101
02-28-2007, 04:19 PM
Originally posted by VW-IceFire:
I think its just incredible that a 60 year old (or older) gun design, the 40mm Bofors, is still having ammo developed for it today. I guess you get to a certain point and the basic principles still hold true.

Parts are still being made to build new Bofors.

Smallest shell of WWII that used the Crosley RADAR
proximity fuses was a 75mm. (WWII vacum tube prox fuses).

RADAR proximity fuses had a failure rate of 50%.
Later before transistors took over it fell
to 10%.

RADAR prox fuses (so called funny fuses)
were not designed to work with any ground based RADAR
or radio transmitters.
They were entirely self contained.

The unit did in fact send a RADAR pulse, and timed the
reflection, within a pre-set range they went BOOM.

Fuses were pre-set at the factory and could not be modded
in the field.

Advantages were obvious.
Primary use in WWII was anti aircraft.
Prox fuses eliminated the setting of detonation
range for big guns.

From roughly the battle of the bulge through the end
of WWII in Europe the prox fuses were used on rockets
and atillery.

RADAR proximity fuses were in use by the US from
the Guadalcanal campaign on in the Pacific.

They were in fact a pre war idea, and were in production
before Pearl Harbor.

RADAR proximity fuses were never developed by any other powers
during WWII. The only other user was the British.

Sergio

Lead-Brick
02-28-2007, 07:53 PM
All you ever wanted to know and more

http://www.history.navy.mil/faqs/faq96-1.htm

Blutarski2004
03-01-2007, 05:57 AM
Originally posted by Sergio_101:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by VW-IceFire:
I think its just incredible that a 60 year old (or older) gun design, the 40mm Bofors, is still having ammo developed for it today. I guess you get to a certain point and the basic principles still hold true.

Parts are still being made to build new Bofors.

Smallest shell of WWII that used the Crosley RADAR
proximity fuses was a 75mm. (WWII vacum tube prox fuses).

RADAR proximity fuses had a failure rate of 50%.
Later before transistors took over it fell
to 10%.

RADAR prox fuses (so called funny fuses)
were not designed to work with any ground based RADAR
or radio transmitters.
They were entirely self contained.

The unit did in fact send a RADAR pulse, and timed the
reflection, within a pre-set range they went BOOM.

Fuses were pre-set at the factory and could not be modded
in the field.

Advantages were obvious.
Primary use in WWII was anti aircraft.
Prox fuses eliminated the setting of detonation
range for big guns.

From roughly the battle of the bulge through the end
of WWII in Europe the prox fuses were used on rockets
and atillery.

RADAR proximity fuses were in use by the US from
the Guadalcanal campaign on in the Pacific.

They were in fact a pre war idea, and were in production
before Pearl Harbor.

RADAR proximity fuses were never developed by any other powers
during WWII. The only other user was the British.

Sergio </div></BLOCKQUOTE>


..... Above all largely true. My only comment is that use of proximity fuzed AA ammunition in the Pacific did not commence until early to mid 1943, which would have been during the Solomons campaign. Guadalcanal had been pretty much wrapped up by that time.

Sergio_101
03-01-2007, 05:05 PM
"This fuze, which was designated the Mk 32, was
delivered to the Fleet during November and
December 1942, and the first Japanese plane
was shot down with proximity fuzed projectiles
by the cruiser [USS] Helena [CL-50] in January 1943."

Quote, www.history.navy.mil (http://www.history.navy.mil)

Above was at Guadalcanal.

Helena was sunk in July 1943 in the Solomons campaign.

Sergio