M61A1 20mm Question

[D-Scythe]

Been returning to some older games lately, and was just wondering: in the M61A1 cannon, as carried by all U.S. fighters, don't the shells fired disperse in a spray like affect? This has the affect of greater area coverage but less damage. Currently, Lock On models multi-barrel cannon fire as an arcing line of death, but in previous Janes study sims, the cannon shells tend to disperse over a much wider area.

 

Anyway, just a thought.

[Dmut]

btw, F/A-18 and F-22 armed with M61A2, it 20% lighter then original M61A1

 

Accoding to General Dynamics site (manufactor of these guns), dispersion for both M61A1 and M61A2 - 8 Milliradians Diameter, 80 Percent Circle.

[D-Scythe]

btw, F/A-18 and F-22 armed with M61A2, it 20% lighter then original M61A1

 

Yeah, something bout composite barrels or something. Same basic system though.

 

Accoding to General Dynamics site (manufactor of these guns), dispersion for both M61A1 and M61A2 - 8 Milliradians Diameter, 80 Percent Circle.

 

Uh, english please? ;)

 

But I'm guessing that there should be more dispersion than there is currently modelled in LOMAC, which has none.

[Dmut]

hehe, are you sure you want English? :)

http://www.gdatp.com/products/lethality/m61a1/m61a1.htm

[MikeRocker]

Well, I have a vid on myHD that clearly shows the A-10's GAU-8 cannon dispersing visibly. And this gun is described as a 'laser' -like weapon in the manual. So would assume that the M61A1 should have noticable dispersion as well. But nothing like a 'shotgun effect' of course!

[Dmut]

GAU-8A is slightly accurate then M61Ax, it has 5 Milliradians dispersion with 80% shots in circle.

 

btw: 0.008 radians ~ 0.458 degree, 0.005 radians ~ 0.286 degree

[olaleier]

Well, I have a vid on myHD that clearly shows the A-10's GAU-8 cannon dispersing visibly. And this gun is described as a 'laser' -like weapon in the manual. So would assume that the M61A1 should have noticable dispersion as well. But nothing like a 'shotgun effect' of course!

 

If my guess is correct, it's a vid with rather saturated colours with the A-10 flying away from the camera right?

 

If it's the one I think, it's from the flight testing. The dispersion shown in that vid would make it useless for anti-tank missions, and I think either the video/perspective/something is lying or it was simply a poor system.

 

I'm not sure how to convert the milliradian figures into the more understandable (for me) "x foot circle at y distance", but this article on SimHQ says 80% of the rounds go through a five foot diameter circle at 1000 feet range.

http://www.simhq.com/_air/air_098h.html

 

Can you just convert the milliradian number into X diameter at Y range?

 

Also check out comparison with VW Beetle :D http://www.simhq.com/_air/air_098ddd.html

[D-Scythe]

So, does everyone sorta agree that there is a lot more dispersion with the M61A1 (in Lock On) than there is currently? Cause right now, it seems to have equal/less dispersion as the GAU-8.

[DropZone]

Can you just convert the milliradian number into X diameter at Y range?

 

To do that, calculating the tangent of the angle and multiplying it by the range should give a close enough answer. So, for the M61:

 

tan0.008 * 1000 = 8

 

 

So that means 80% of the rounds would go into an 8 feet diameter circle at 1000 feet (assuming I've worked this out right).

 

edit: In fact, the number of milliradians is almost exactly the diameter of the circle it'll go through at 1000 feet. So for the GAU-8, 5 milliradians = 5 feet dispersion at 1000 feet, and for the M61 8 milliradians = 8 feet.

[olaleier]

Thanks DropZone, I only have vague memories of attending geometry class. :lol:

 

 

So, does everyone sorta agree that there is a lot more dispersion with the M61A1 (in Lock On) than there is currently? Cause right now, it seems to have equal/less dispersion as the GAU-8.

 

I don't trust a gamer to do it with eyesight on his 2D monitor. Perhaps we could find out a way to test it?

[D-Scythe]

So that means 80% of the rounds would go into an 8 feet diameter circle at 1000 feet (assuming I've worked this out right).

 

edit: In fact, the number of milliradians is almost exactly the diameter of the circle it'll go through at 1000 feet. So for the GAU-8, 5 milliradians = 5 feet dispersion at 1000 feet, and for the M61 8 milliradians = 8 feet.

 

Thanks DropZone.

 

Do you know how the relationship between distance and dispersion well enough to tell us the diameter of the circle the rounds would go through at half a mile? One mile? Cause I really think it's too small in LOMAC. Thanks.

[GGTharos]

Last I heard the Vulcan had a dispersion of 6' at 1 mile. Couldn't been 1000' though, in which case we're looking at 36' at 1 mile ;) I don't really recall.

[olaleier]

Last I heard the Vulcan had a dispersion of 6' at 1 mile. Couldn't been 1000' though, in which case we're looking at 36' at 1 mile ;) I don't really recall.

 

Source?

 

Here's GAU-8 dispersion at 1NM: http://www.simhq.com/_air/air_098yy.html

 

A bit more than 6'.

[GGTharos]

Not the GAU-8. THe Vulcan. I don't recall the source, it probably was in one of the F-16 manuals.

[DropZone]

So that means 80% of the rounds would go into an 8 feet diameter circle at 1000 feet (assuming I've worked this out right).

 

edit: In fact, the number of milliradians is almost exactly the diameter of the circle it'll go through at 1000 feet. So for the GAU-8, 5 milliradians = 5 feet dispersion at 1000 feet, and for the M61 8 milliradians = 8 feet.

 

Thanks DropZone.

 

Do you know how the relationship between distance and dispersion well enough to tell us the diameter of the circle the rounds would go through at half a mile? One mile? Cause I really think it's too small in LOMAC. Thanks.

 

I reckon that at one mile, the dispersion would be:

 

26.4 feet for the GAU-8

42.2 feet for the M61

 

At half a mile:

 

13.2 feet for the GAU-8

21.1 feet for the M61

 

Bear in mind that I'm not certain I'm working this out right - here's how I'm doing it, so if anyone who knows a bit more about this than me could check if I'm doing it right, I'd be grateful :)

[GGTharos]

Looks about right for both of them - it's been said that the GAU-8's dispersion at 1nm is 30', and other times I heard it's 20', so your value is pretty close.

 

The value for the M61 coresponds to about one foot more than what I said at 1000', so that looks right as well. Good stuff! :D

[olaleier]

Not the GAU-8. THe Vulcan. I don't recall the source, it probably was in one of the F-16 manuals.

 

I know, just using the GAU-8 for comparison since it's supposedly more accurate.

[MikeRocker]

If my guess is correct, it's a vid with rather saturated colours with the A-10 flying away from the camera right?

 

Hi Ola

 

Yup, that's the one. Just watched it again and, even taking the perspective and camera lens effects into account, it is pretty horrible spread in that case.

 

But we all must remember that these measured degrees of dispersion apply only to stationary guns. The aircraft forward motion and any maneouvers strongly affect the bullets' flightpath and dispersion.

[Vati]

I do not really see why is there so much speculation going on.

Manufacture data says GAU8 has 5mils 80% and M61 8mils 80% (however note that this is for fixed system as MikeRocker has already said. The actual dispersion is a bit higher due the recoil force relation to the cg of a/c)

Also a tip for the future... Those who were not in army should google how to make easy calculation with mils so no to get lost in the trigonometric functions ;)

 

Looks about right for both of them - it's been said that the GAU-8's dispersion at 1nm is 30', and other times I heard it's 20', so your value is pretty close.

 

The 30' and 20' approximations are the same figure. Only difference is in which mile you are trying to represent the dispersion value ;)

So GAU8 at statute mile is 5.280 * 5 = 26.4ft; while at nautical mile it is 6.076 * 5 = 30.38ft.

 

As for LOMAC... all guns are too accurate, with GUA8 being the most close to the real figures.

To test this, simply create mission either w/ static target on ground or flying and then fly to the range and fire w/ trimmed a/c. You will notice that it is too accurate even w/ wobbling around... ;)

[D-Scythe]

As for LOMAC... all guns are too accurate, with GUA8 being the most close to the real figures.

To test this, simply create mission either w/ static target on ground or flying and then fly to the range and fire w/ trimmed a/c. You will notice that it is too accurate even w/ wobbling around... ;)

 

More like the gunfire is too dense, especially for the M61, as the extra dispersion can vastly increase the hit chance of a single burst of 20 mm shells, for the loss of significant lethality.

[Omega Oska]

BTW, has anyone ever seen any A2A kills with guns. I've never seen one except in movies or anime.

 

If someone can find a clip or even a photo on this, things should be more clear.

[GGTharos]

With modern jet fighters? There are clips of exercises but never gunfire.

 

There are clips from WW2 shooting down aircraft with guns.

[olaleier]

Perhaps there are some from Vietnam. Some places sell DVDs with various guncamera footage etc, but the only clips of A2A kills in Vietnam I've seen on the net has been the various famous Sidwinder shots.