25mm APFSDS experimentals


#1

Some years ago (1992-ish) I acquired a large assortment of aluminum 25mm sabot pieces that came from a firing range at the USMC base Camp Pendleton. There were 4 or five distinct variations of sabot types. Some were two-piece, some were four-piece and the larger portion were three-piece. The most interesting thing was that each piece was hand engraved with a number and letter. For example, a three piece sabot would be numbered 203-A, 203-B and 203-C. Obviously these were experimentals, but why were they fired at Camp Pendleton? Why were the sabot pieces not recovered if they were numbered, apparently to identify location after firing? Any information on this program would be appreciated. The best examples and complete matched sets now reside at the Woodin Laboratory just in case anyone was curious.

AKMS


#2

Camp Pendleton probably was the closest range that permitted firing that caliber in relation to the company doing the work. That’s not uncommon.

Could also have been some sort of USMC demo. as well.

As to why they didn’t recover the sabot petals, anybody’s guess there.


#3

Well, it is obvious, I love the APFSDS stuff. Would love to see some pics if you have any. FYI, all of my large caliber SABOT rounds have individualy labled sabot petals. I know in the RD stages, each petal is identified to study thier distribution pattern after test firing. That being said, even the tacticle rounds are labled, A,B, & C, ect., so go firgure?

Jason


#4

The only weapon used by the Marines at that time firing the 25mm DS ammo was the Harrier jump jet. These may have been filmed when they were fired. Too many unknowns in the story. Lockheed, Aerojet and others had (have) plants in that area which could have been doing tests there. Fired 25mm sabots are usually pretty torn up. How did they look ?


#5

How about the general rule that APDS/APFSDS ammo is not fired by forward firing aircraft? It is even written on some 20x102 cases loaded with such projectiles. (I’m sure you have seen such ones)


#6

I never saw that. Would love photos if they are out thier :-) I always thought the Warthog Plane (A10 I Think) utilized APFSDS in thier front 30MM Canon as a option? I could easily be wrong. I have a nice 30 MM APFSDS round, but have no clue what it goes to. Has very few markings on it.


#7

The 30mm GAU-8/A as used in the A-10 is not using discarding sabots.

Here the text as used on 20x102 cartridges:


#8

Sweet info! Thanks EOD!!! The thrill of solving a mystery. Really apreciate all your help id’ing things.


#9

Just currious what this 30MM is and what shoots it? I always thought it was the A10?


#10

How about an image of the projectile without case?


#11

Thanks for your help (AGAIN) EOD! Here are a few pics.

Note, each petal is labled with the same part # followed by a #1,#2,#3, & #4.

I am assuming that this may of had a plastic windshield at one time? The Sabot petals are alluminium.


#12

The pod nature of Harrier 25mm weapons puts this problem out of the way. Have a look at it.

The GE GAU 12U 25mm cannon on the Harrier is well below the engine intake and fires well south of it. DS ammo is not a problem for this craft-it may be for your wing man but that is a standard problem with all DS ammo used in aircraft. The 12U is both below and behind the engine intake. Any sabot fragments fall below the platform.

They could also have been testing the Hughes m242 helo chain gun. These are chin guns and the helo intakes are above the platform.

DS ammo is a problem for the A10 because the engines are to the rear of the guns. A burst and a change in direction could suck a pile of DS pieces into the engine- NOT GOOD. Although the A10 usually fires DOWN and away from the air stream of the engines things can and do change rapidly with jet aircraft and the advantage of DS ammo is not worth the risk.

You are correct that DS ammo is a problem with aircraft and this was proven in TESTING. Good luck recapitulating test design parameters based upon second and/or third hand testimony about recovered evidence which story may or may not be true. A look at the evidence would be the best place to start.


#13

Well, the Harrier can “hover”, beside this the sabots still move along some part of the trajectory (to the front) and there it does not matter if the gun is like 3ft behind the air intake or not.
Some Harrier pilot or Marine armourer may tell us in detail what is being used. The regarding AP round is the PGU-20. (DU type)
globalsecurity.org/military/ … pgu-20.htm

APFSDS
Interesting projectile you have, since it is not crimped to the case you have it will be just a guess. Most likely it is for some ground based or helicopter based system (if at all) since regular forward firing aircraft will not use it and the only one firing sideways is the AC-130 and this one was using APFSDS in 20x102 and 40x311R and soon 25x137.


#14

I have never heard of saboted ammo being issued for aircraft use, with a couple of specific exceptions. As soon as the projectile leaves the muzzle, the irregularly-shaped sabot pieces can fly just about anywhere, and there is always a risk that they will be sucked into the engine almost regardless of the intake location. This is a problem even with plastic sabots, because they melt and coat the turbine blades, affecting their balance - and they are the devil to clean off. Some experimental work was done decades ago on sabot catchers - devices in front of the muzzle to trap the sabot fragments - but these were very bulky and not 100% effective anyway.

As a result, the 30mm GAU-8/A and 25mm GAU-12/U aircraft AP rounds are DU-cored APCR (PGU-14/B and PGU-20/U respectively) - the entire projectile holds together until target impact.

The two exceptions I know of are as follows:

  1. The 20x102 Mk 149 APDS (developed for the Phalanx CIWS) has been cleared for use in the M197 gun fitted to the USMC’s AH-1W SuperCobra helo, presumably because the rotor downwash blows the light sabot petals away from the engine intakes.

  2. The 40x311R Bofors used in the AC-130 gunships had an APFSDS round developed for it (the PGU-31B), presumably because the side-firing gun was mounted well behind the engines. This was not adopted for service, however - I suspect because the c.200 mph crosswind hitting the fins didn’t do much for the accuracy…


#15

Actually, engines aren’t the only concern with aircraft firing saboted rounds. Discussions I’ve had with an active Boeing engineer pointed out that firing full auto cannon with saboted ammunition results in a cloud of debris that you then have to fly through. Damage to leading edges, canopy, anything exposed to the air stream can be significant with a long burst, or even shorts bursts, cumlative, over time.

Also, aircraft aren’t the only role for saboted medium caliber rounds. We’re all familiar with the Bardly AFV that uses a 25mm chain gun, saboted round, as well as the new, proposed USMC AFV that would mount the 30mm GAU-8 type round, but in a single barrel chain gun, rather than the A10’s gatling gun. That design has already been tested with an Discarding Sabot load.

The new Spectre C130 gunships 30mm will load out with a DS round as well. Side-firing, I guess the sabots fly far enough away, behind, and below to not be a problem.


#16

[quote=“Tony Williams”]I have never heard of saboted ammo being issued for aircraft use, with a couple of specific exceptions. As soon as the projectile leaves the muzzle, the irregularly-shaped sabot pieces can fly just about anywhere, and there is always a risk that they will be sucked into the engine almost regardless of the intake location. This is a problem even with plastic sabots, because they melt and coat the turbine blades, affecting their balance - and they are the devil to clean off. Some experimental work was done decades ago on sabot catchers - devices in front of the muzzle to trap the sabot fragments - but these were very bulky and not 100% effective anyway.

As a result, the 30mm GAU-8/A and 25mm GAU-12/U aircraft AP rounds are DU-cored APCR (PGU-14/B and PGU-20/U respectively) - the entire projectile holds together until target impact.

The two exceptions I know of are as follows:

  1. The 20x102 Mk 149 APDS (developed for the Phalanx CIWS) has been cleared for use in the M197 gun fitted to the USMC’s AH-1W SuperCobra helo, presumably because the rotor downwash blows the light sabot petals away from the engine intakes.

  2. The 40x311R Bofors used in the AC-130 gunships had an APFSDS round developed for it (the PGU-31B), presumably because the side-firing gun was mounted well behind the engines. This was not adopted for service, however - I suspect because the c.200 mph crosswind hitting the fins didn’t do much for the accuracy…[/quote]

Again, this question was not about what is being “issued”. It is a question about was may have been TESTED. DS apples and DS oranges.

Have you ever heard of DS ammo being TESTED for aircraft use ?

How would you know about scraping plastic sabot parts off engine parts ?

Is this real information or your opinion ?


#17

[quote=“50m2hb”]Actually, engines aren’t the only concern with aircraft firing saboted rounds. Discussions I’ve had with an active Boeing engineer pointed out that firing full auto cannon with saboted ammunition results in a cloud of debris that you then have to fly through. Damage to leading edges, canopy, anything exposed to the air stream can be significant with a long burst, or even shorts bursts, cumlative, over time.

Also, aircraft aren’t the only role for saboted medium caliber rounds. We’re all familiar with the Bardly AFV that uses a 25mm chain gun, saboted round, as well as the new, proposed USMC AFV that would mount the 30mm GAU-8 type round, but in a single barrel chain gun, rather than the A10’s gatling gun. That design has already been tested with an Discarding Sabot load.

The new Spectre C130 gunships 30mm will load out with a DS round as well. Side-firing, I guess the sabots fly far enough away, behind, and below to not be a problem.[/quote]

Is this information the result of TESTING or conception?


#18

The C130 info is based on the new mod of Spectre. They’re replacing the 40mm cannon. The bird was sitting outside his office, he sent photos. There was also an article in, I believe, Air Force Times that came out the same month on the new version, first aircraft then being delivered.

The AFV was an NDIA article I believe. I think that’s farther upstream, though, more like prototype or concept stage.


#19

I meant the part about the DS cloud.


#20

It was originally, but I was responding to the subsequent discussion about whether or not DS projectiles were used in aircraft. Threads have a habit of drifting away from the original question - live with it!

[quote]Have you ever heard of DS ammo being TESTED for aircraft use ?

How would you know about scraping plastic sabot parts off engine parts ?

Is this real information or your opinion ?[/quote]
See page 114 of “Historical Development Summary of Automatic Cannon Caliber Ammunition: 20-30 Millimeter” by Dale Davis, published by the (US) Air Force Armament Laboratory. Davis worked in that lab, developing that ammo, and this publication is essential reading for anyone interested in this subject.