50cal dispersion?

I've seen some vids of real Kiowa's firing the 50 onto a hill, and there appeared to be some dispersion even from modest distances. That is to say, when the pilot holds steady, there is still a bit of "shotgun" pattern to the rounds hitting. I mean, the heli is vibrating, winds buffeting, the mount would vibrate under recoil, and so on.

I also saw one of the preview live streams, and in it one of the participants straffed an airfield with the 50. It seemed to provide a "laser" like performance, as if you could reach out quite far and have precise hits.

Now, It's my understanding that the stream featured an already out of date build, and that this is still some ways from becoming the final product... but is it planned for the gun to have some dispersion, for the final product?

Have your real Kiowa friends mentioned this to you?

Note, also the rate of fire in the real video seemed slower than in the sim livestream too

The minigun should have a fairly good spread, like look this AH-1G Huey Cobra armament systems video:

Even when its minigun is well mounted, it has 18 mils CEP. That is a huge, compared to ie A-10 GAU-8 cannon that has only 5 mils, so that is over three times wider spread than what larger caliber cannon has.

But as you wouldn't want such laser with it, because quick spray at the direction of enemy (muzzle flashes etc) and you should be able saturate that few square meter area full of bullets, and as likely there is a whole team or squad in treeline etc, capability to put 500 rounds on that 20-70 meters wide area is effectiveness.

Not sure why the talk of Miniguns, as the Kiowa D seems to only use M3 '50cals, not the much smaller Miniguns.

I agree, the dispersion would seemingly help the pilot at closer ranges, seem to be more realistic, and that's what I'd like to see: a realistic amount of dispersion,.

I've seen some vids of real Kiowa's firing the 50 onto a hill, and there appeared to be some dispersion even from modest distances. That is to say, when the pilot holds steady, there is still a bit of "shotgun" pattern to the rounds hitting. I mean, the heli is vibrating, winds buffeting, the mount would vibrate under recoil, and so on.

 

 

I also saw one of the preview live streams, and in it one of the participants straffed an airfield with the 50. It seemed to provide a "laser" like performance, as if you could reach out quite far and have precise hits.

 

Now, It's my understanding that the stream featured an already out of date build, and that this is still some ways from becoming the final product... but is it planned for the gun to have some dispersion, for the final product?

 

Have your real Kiowa friends mentioned this to you?

 

Note, also the rate of fire in the real video seemed slower than in the sim livestream too

The Kiowa has a more vivid dispersion than a fixed, ground .50 cal would because it is mounted on an aircraft. The Kiowa is a light helicopter (5200 lbs. max gross weight) meaning that the recoil from the M3P has a significant effect on the aircraft, the whole helicopter shakes. When you squeeze the trigger the -58 will yaw left, the pilot has to anticipate this yaw and apply right pedal as the gun is fired. The same yaw happens as a Hellfire is fired too, but with the Hellfire it is momentary.

Hi,

So the minigun GAU19 had less dispersion then the M3P on the Kiowa Warrior. One of our SMEs, SABER, was on the evaluation team of that system.

The M3P has some recoil yes, but it is not as much as peoeple think it is, cause the slipstream of the aircraft helps to counter it.

The Hellfire does not indeuce jaw when fired fro. the rack. the racks have a friction setting. that holds the missile. on the rack but it is not. enough to actually induce any jaw to the airframe when the motor has to overcome the friction to slide the missile from the rail. Plus the is no barrier behind the misdsile exhaust that would encounter a blast recoil.

We have discussed that briefly in the team with the SMEs month ago already and recieved the info needed.

For the value of the friction of the rack I have to ask them again. I do not remember that out of the top of my head.

Hi,

So the minigun GAU19 had less dispersion then the M3P on the Kiowa Warrior. One of our SMEs, SABER, was on the evaluation team of that system.

The M3P has some recoil yes, but it is not as much as peoeple think it is, cause the slipstream of the aircraft helps to counter it.

The Hellfire does not indeuce jaw when fired fro. the rack. the racks have a friction setting. that holds the missile. on the rack but it is not. enough to actually induce any jaw to the airframe when the motor has to overcome the friction to slide the missile from the rail. Plus the is no barrier behind the misdsile exhaust that would encounter a blast recoil.

 

We have discussed that briefly in the team with the SMEs month ago already and recieved the info needed.

 

For the value of the friction of the rack I have to ask them again. I do not remember that out of the top of my head.

With all due respect to your SME and your team, I'm going to disagree with you. When I have fired the Hellfire there is a momentary yaw before the missile breaks away. The missile doesn't breakaway until it reaches 500-600 lbs. of thrust, there is a yaw until that breakaway happens. The M3P doesn't have the same recoil as the XM296, but it will still cause yaw when fired. Running and diving fire are significantly more accurate than hover fire (this includes firing rockets) but the yaw is still there and has to be compensated for by the pilot.

Another SME for the OH58-D, Nice! Go sign up with the PC team and make sure your input is heard there with all the other SMEs!

At risk of jumping in and chumming the waters of internet opinions, I'll offer a couple points for consideration. Acknowledging that we all have our own experiences and judgements derived from them, I'm going to comment by offering my own observations and some lessons learned over the years.

To the points above:

Hellfire: While the hold-back mechanism does indeed require up to 600 lbs of force to release the missile, the launch thrust is so great and happens so fast there is really no time for the moment of inertia in the aircraft to be overcome in the split-second it takes the missile to leave the rail to produce a 'significant' yaw. By 'significant' I mean enough for the pilot to perceive. Rather, I attribute any noticeable yaw to pilot-induced control pressures at the moment of firing; in fact most likely in cyclic movements as he presses the fire button. It doesn't take much, and the act of pressing the fire switch and tensing on the controls will be noticeable in unwanted motions of the entire airframe. Obviously I don't know your own experiences or experience, but I offer that a measured yaw affect attributed to missile thrust would have been noted in test and documented accordingly. The engineers would have cried "foul" at induced yaw, as this would have directly contributed to tumbling the gyros as the missile leaves the rail.

As to firing the .50 cal: there shouldn't be any noticeable difference between the XM296 and the M3P in terms of 'yaw' produced. They're firing the same bullet, so no difference in applied forces due to firing.

Again, perceived yaw and dispersion when firing either .50 cal is mostly due to pilot-induced control movements. For the benefit of those who haven't had the pleasure of firing the gun on this aircraft; the event is emotionally significant, as the muzzle is about two feet and slightly back from the left-seater's door. The muzzle shock-wave, especially of the M3P, will rattle your teeth if you're not paying attention, and forget to close your mouth when the right-seater pushes the trigger. Further; I'd offer that most newer pilots tense on the controls when firing, and coupled with the "unusual" firing button arrangement which places the weapon fire button underneath the thumb instead of a more standard "trigger", there is a natural tendency to tense the arm.

But mostly; it's pedal control (or rather, overcontrol) which leads to the perception there is significant yaw going on. The dispersion pattern of XM296 vs M3P was significantly different, due to the mount structures on the pylon, and cyclic rate of each gun. The low-slung cage of the XM296 has a longer "arm" than the M3P, and recoil thus caused much more movement.

Both being recoil-operated with a heavy reciprocating bolt sliding back-and-forth on a single barrel, the resultant vibration and harmonics produced are significant. But mostly dispersion is due to the pilot adding unintended control inputs when firing.

<edit> I acknowledge there is some yaw induced due to the physics of firing .50 cal rounds on one side of the airframe, however I am willing to argue that "perceived" yaw is mainly attributed to flawed technique during the firing sequence. The M3P has a known flaw in that it was generally accepted to fire high and left due to a design flaw in the mount. It was difficult to boresight in-line with the rockets at a specified range. So; first rounds generally were off-target based on a "natural" sight picture and learned aircraft setup when compared to a similar distance rocket sight-picture. This tended to influence the perception of some pilots that a "yaw" was induced when firing. Coupled with other generally unperceived control inputs at the moment of firing, it's easy to believe that gun firing is producing a consistent "yaw".

Last - when bringing GAU-19 into the mix; that gun was sweet. Because it was electrically driven and had no reciprocating mass to cycle rounds, the transferred recoil to the airframe was very different than the single-barrel guns. The mount was also much more robust and stiff. On firing, there was much less dispersion, and the rounds impacted in a very tight beaten zone. In the hands of a capable pilot, it was much easier to drop a higher percentage of rounds on the intended target.

Now rockets...oof. That's a whole 'nother rant.

Ok so Barandus, are you saying that other than the "high and to the left" shift (not unusual with auto wpns), that generally the M3P didn't have much natural dispersion? meaning the beaten zone is quite tight, more affected by pilot errors than the recoil, vibration, mount and moving parts?

Note: I'm not disputing your statement, just looking for clarification!

I have experience with the Browning, but mine would be an apples to oranges comparison, as I've used the ground version, on tripods and a cupola/hatch mount... the mounts are more loose, the barrel much physically heavier, rate of fire and moving mass much different and so on!

Rick,

The "high/left" shift is just a boresight error due to the gun mount design. Typically the M3P boresight was just a tad off, because the armament guys could never quite get it aligned properly to the aircraft centerline. So we resorted to drawing two "pippers" on the windscreen, one for rocket, the other for the gun.

To dispersion; The M3P dispersion was still pretty significant, but not as noticable as XM296. And you're right: pilot-induced dispersion was by far the greatest contributor. In the hands of an experienced pilot, M3P dispersion was 'not bad'. Also, the higher cyclic rate helped.

In order from worst to least (in relative terms) for dispersion:

XM296

M3P

GAU19

The GAU had a really tight beaten zone, but of course never fielded to operational units.

Hmm, yea I can imagine mounting on a hardpoint would complicate boresight! I seem to recall that was a significant issue in the 1960's with the Phantom F-4, because so many of them were using the M61 20mm cannon in pods on hardpoints. They worked just fine... but getting them to line up with the gunsight was apparently a nightmare and sometimes they just couldn't get it done properly. I think that's why the later ones had the extended nose and internal gun: to have a proper boresighted cannon. (Sometimes these Phantoms would be seen with three 20mm pods!!)