Aircraft weapons

[pdoktar]

The Mk44 has APFSDS ammo. No?
The GAU-8 has only APDS ammo. No?

APFSDS is made to have more penetration capability than APDS. I can see no other reason to make such a complicated round if it has not got something to offer. The only thing that an APFSDS has to offer is more penetration and range having that penetration capability.

APDS is inferior in penetration to APFSDS if properly designed and fired from the same gun. The case diameter and lenght are the same for GAU-8 and Mk44, but Mk44 can fire the APFSDS ammmo that GAU-8 probably can too, but mounted on the A-10 can not, since the sabot petals would interfere with the airframe.

You can give some extra pen for the A-10 because the weapon muzzle velocity gets an increase from the speed of the aircraft it is flying when firing. However you can hardly argue that a modern APFSDS has worse pen capabilities than a 1970s APDS.

I personally think that a good 100 round burst hitting a MBT will at probably result in a mobility kill, or not. The engine deck and fans above it, tracks, track guards, main gun etc are vulnerable to the GAU-8. The high rate of fire is probably because of getting multiple hits to the targets in one attack thus increasing the chances of damaging tanks weaker parts.

BTW how many MBT kills did A-10s have in GW1 just using the main cannon.. I´ve only heard of light AFVs, trucks, AA assets which are easily penetrated by the GAU-8 and make up the majority of vehicle targets in any battlefield thus giving the GAU-8 plenty of use even if it called a "tankbuster". Just remember that for example the media refers anything with tracks as a tank, so the tankbuster can really wreak havoc among those "tanks".

[Marcello]

I think there are some misconception about the nature of the PGU-14 fired by the GAU-8. Such round, as the cutout picture I have posted clearly show, is neither an APDS nor APFSDS, where the DS stand for Discarding Sabot. In such a configuration an high density, sub caliber penetrator is surrounded by lightweight petals which are discarded after the round leaves the muzzle in order to reduce aerodinamic drag. No such thing for the PGU-14, as the discarded petals could be sucked into the engines with the all too predictable consequences. Therefore while a subcaliber penetrator is used in the PGU-14 this is more in the fashion of APCR of WW2 vintage, with the aluminium jacket retained until the impact with the target. The drawbacks of this configuration, especially at long range, were well known even during WW2 but as I said its employment was dictated by the circumstance of its use inside an aircraft.
Note that even if you don't trust me the round is referred to as AP rather than APDS or APFSDS.As I said no DS.

"Tungsten tends to blunt its own tip and even shatter at very high velocities while a DU round self sharpens until it penetrates or runs out of energy and destroys itself."

Actually as it has been debated to death on tanknet at really extremely high velocities it is tungsten that all else being equal (quality of manufacturing,tech level , alloying etc) has an edge on DU but that is not particular important for the current round speeds as far it was understood. What it should be remembered in context is that DU has come under heavy political flak (some of it unjustified IMHO) and the DOD has had to defend its use. Some inflating of its real advantages and cherry picking of evidence went in par the course.
I hope to write something more about it later if I can find the time.

[Marek_Tucan]

I think the "Tungsten blunting" did happen with lower quality tungsten alloys, ie upon its introduction (early 1980's?) the DU should have an edge here, but my understanding is also that current tungsten penetrators should be at least equal to DU.

[thatguy96]

So I went and checked the sources on the "DU is superior and Tungsten blunts on impact" comments repeated on Globalsecurity.org and most of them come from US government documentation defending the resumed use of DU ammunition in light of the massive debate about the health consequences. While it is obvious that at least in some cases the point holds true, those kind of government documentation are not exactly the best for making determinations about the real effectiveness of a system.

That picture of the round shattering doesn't show what the rounds look like beforehand, what gun they were fired from, etc. So while it obviously does happen, we don't know what the circumstances of its occurrence are.

[kevineduguay1]

As I said before ALL DU penetration stats are CLASSIFIED. The 69mm at 500 meters figure just does not add up.
Again why would the US invest all that time and money to create this huge weapon and have it only slightly out perform a weapon like the German WWII era 28mm sPzB41 (pen 66mm at 500 meters)? I know that the Pen value in the game for the GAU-8 is 9 or 90mm but again this fits just right with the Ger 28mm weapon. Notice that when a A-10 makes a gun run in the game the last attack is said to come from 200 meters. At 200 meters the 28mm sPzB41 has a pen value of 86. In the game this would also rate as a 9 Pen value.
Im not looking to create a "uber weapon" just something closer to the real thing.

thatguy96,
I can use the same argument against you about the Bushmaster MK44. Cute picture of the round but where is it written that this 30mm weapon can punch 120mm of armor? Is that source reliable or is it just some trumped up figure put out by some US Government agency to legitimize the funding for this project?
Two of my quotes are from other sites and do not parrot Global Security.

The Bushmaster can fire a APFSDS round that may and probably does give it a slight edge over the GAU-8. The GAU-8 round is totaly self contained just like that pesky 28mm German squeeze bore. But given same size penetrators of tungsten and DU, the DU penetrator wins in the weight competition and in the penetration competition.

[thatguy96]

kevineduguay1 said:
As I said before ALL DU penetration stats are CLASSIFIED. The 69mm at 500 meters figure just does not add up.
Again why would the US invest all that time and money to create this huge weapon and have it only slightly out perform a weapon like the German WWII era 28mm sPzB41 (pen 66mm at 500 meters)?

Because its cheaper and easier? As far as, I know the GAU-8/A and its ammunition do not rank up as one of the costlier weapon systems ever developed by the US military. There is also not a wealth of documentation on the supposed superiority of DU prior to the health impact scandal. There is, however, a wealth of documentation that talks about the ease and low cost of manufacture, and the availability of the material as a byproduct of nuclear power production.

kevineduguay1 said:
thatguy96,
I can use the same argument against you about the Bushmaster MK44. Cute picture of the round but where is it written that this 30mm weapon can punch 120mm of armor?

Never said it could. In fact I have not quoted any penetration figures. I just said that it was obvious that somewhere someone along the way made a design decision based on information likely to do with the difference in rounds used by the different weapons.

kevineduguay1 said:
Is that source reliable or is it just some trumped up figure put out by some US Government agency to legitimize the funding for this project?

I never said it was, and I never said it wasn't. So you could be exactly correct on both points.

kevineduguay1 said:
Two of my quotes are from other sites and do not parrot Global Security.

I checked all the sites you linked and their citations. You can look at them yourself.

kevineduguay1 said:
But given same size penetrators of tungsten and DU, the DU penetrator wins in the weight competition and in the penetration competition.

Again, I've seen nothing that conclusively proves that point or to a point where I am anywhere as convinced as you obviously are.

[kevineduguay1]

Again I ask, why mount the huge GAU-8 whan a much smaller weapon could do the same job? If it did not have a distinct advantage why not just use a 20mm Vulcan?
With all the research that went into the GAU-8 weapon they couldn't make it any better than a WWII era heavy anti-tank rifle?

[Marcello]

"Again why would the US invest all that time and money to create this huge weapon and have it only slightly out perform a weapon like the German WWII era 28mm sPzB41 (pen 66mm at 500 meters)?"

Some points to consider
1) The sPzB41 achieved those performances by being a bleeding edge, over engineered, limited production item with several issues (barrel wear inherent to the taper bore designs etc). GAU-8 ammo was designed to be practically made and expended in immense quantities.
The drag issue associated with what is an APCR design have already been noted.
GAU-8 ammo has been around for what must be over 30 years now, so it is not exactly a recent design either.

2) The "it is WW2 level stuff" claim is not sound by itself. You could knock out an Abrams with a WW2 vintage Panzerfaust. That does not make the Abrams a poor design, does it?

3) The GAU-8 high ROF means higher HE kill against soft targets, less time spent on target and to an extent greater probability of hitting the target. Such things are not directly related to each round penetration.

4) Speaking of hitting probability I have an hard time imagining how you could hit a tank size target more than six kilometers away with a fixed gun mounted on a plane.

"Im not looking to create a "uber weapon" just something closer to the real thing."

If you had an alternate a source claiming that it was let's say 88mm at 500 meters rather than 69mm it would be something we could accept without much fuss. As it is you were asking for it being capable of extreme performances (knocking out tanks at 6000 meters and the like) based on little of substantial.