Author Topic: 23 mm High Altitude Recoilless Multi Stage Gun (Read 2054 times)

Numbers · « **on:** February 16, 2012, 05:05:23 AM »

Below I discuss the theoretical concept of 23 mm High Altitude Gun.
Its rounds reach 5,000 m/s velocity. The gun designed as Recoilless Multi Stage Gun.

Some Physics:

Kinetic energy is KE = (mass x Velocity^2) / 2
Kinetic energy is prime factor in armor penetration calculation.
If we increase velocity of ZU-23-2 round five times (from 970 m/s to 5,000 m/s)
then we increase Kinetic Energy 25 times over.

The solution to armor penetration lies in increasing velocity of round
and not its mass.

More Physics:

Also for gun round to reach 20 kilometers altitude it is necessary
to increase its velocity. If we increase velocity of ZU-23-2 round five times
(from 970 m/s to 5,000 m/s) it will reach 20 kilometers altitude.

The idea is to have Anti Aircraft Gun that fires small in-expensive rounds
but can hit at high altitude of 20 kilometers.

Such Anti Air Gun's projectiles are in-expensive 186 grams (like ZU-23-2) tungsten bullets
that once leaving the barrel will fly only using force of blast that happened in the barrel.

Consider this as large caliber machine gun that can hit targets at altitude of 20
kilometers. If Aircraft flies at 20 kilometers the machine gun operator has
to aim ahead of Aircraft's path since round will reach 20 kilometers altitude in
4 seconds. (5,000 meters/second x 4 seconds = 20,000 meters)

The only way to achieve 20 kilometers altitude is to have more powerfull
chemical explosion in the gun's barrel.

Current Anti Air Guns like ZU-23-2 have already achieved maximum possible
force of chemical explosion in their barrel.

Concept of "Multi Stage Recoilless Gun":

The only way to increase force of chemical blast that accelerates projectile
is to use concept called "Multi Stage Recoilless Gun".

The principle is simple. The gun's barrel is opened on its back side allowing
explosion gas to escape without blowing up the gun barrel.

There is another principle. If gun's barrel is 6 meters then projectile round
can be accelerated by chain of 5 explosions.

5 explosions in a chain accelerate projectile round to high speed.
1 explosion by itself is not powerfull enough to damage
the barrel. 5 of those explosions (one after another) accelerate the projectile round
to very high speed without damaging the barrel.

And since gun is opened on the back side, gas after each explosion is blown away
from the back side of gun without accumulating.
Gas is not accumulated after 5 explosions and is blown away after each single explosion.

Assuming tungsten Sabot round is 0.2 meters in length. Then we add 5 chemical propellant
cases 0.2 meters each.

That gives us 1.2 meters Sabot round. Chemical propellant cases are packed into plastic cylinders.
(so no metal is used in Sabot propellant cases desing).

Once Sabot round is fired it starts accelerating through 5 meters of stainless steel barrel.
Each meter one more additional propellant case is detonated. 5 meters of gun barrel =
5 consequent detonations.

Detonations of acceleration propellant cases happen one after another and none of them
damages the barrel. All explosions gases after each detonation are exhausted from the back of the gun.
(Recoilless Gun)

Muzzle velocity of ZU-23-2 Anti Air Gun round is 970 m/s.
If we have 5 detonations we theoretically can increase velocity 5 times to 5,000 m/s.

With such velocity Sabot round can reach 20,000 meters altitude in 4 seconds.

Any Aircraft even high flying one will be in reach of Recoilless Anti Air Gun.

On top of it, 5,000 m/s speed will make Sabot round highly damaging to Tanks on the ground.
Since Kinetic Energy of round will be increased 25 times. Armor Penetration will be higher 25 times.

Air Resistance will be small since round diameter is only 23 millimeters.

Obviosly guidence system for Recoiless Anti Air Gun will consist of small Phased Array Radar
and Electro Optical Sensors (Nightvision and Infrared).

Pictures below are:
Diagram of Recoilless Gun,
Pictures of current tanks Sabots,
Pictures of currently deployed ZU-23-2 Anti Air Gun.

comandantecarlos · « **Reply #1 on:** February 16, 2012, 07:20:36 AM »

I recommend one of these:
http://www.military-today.com/artillery/type_87_spaag_images.htm

comandantecarlos · « **Reply #2 on:** February 16, 2012, 07:24:18 AM »


LiveLeak.com - Type 87 SPAAG Firing (Anti-Aircraft Gun)	Small \| Large

Catsoo · « **Reply #3 on:** February 16, 2012, 03:01:14 PM »

comandantecarlos

Your link is dead!

catsoo

comandantecarlos · « **Reply #4 on:** February 16, 2012, 07:28:17 PM »

I do not know why you can not see. There are 3 pictures

Numbers · « **Reply #5 on:** February 17, 2012, 07:20:52 AM »

comandantecarlos, what are the altitude and range of Type 81 Self Propelled Anti Aircraft Gun?

comandantecarlos · « **Reply #6 on:** February 17, 2012, 07:30:11 AM »

Entered service   1987
Crew   3 men
Dimensions and weight
Weight   44 t
Length (gun forward)   7.62 m
Hull length   6.7 m
Width    3.2 m
Height   4.1 m
Armament
Main gun   2 x 35-mm
Machine guns   -
Projectile weight   0.55 kg
Maximum slant range   4 km
Maximum firing range   12 km
Rate of fire   1 100 rpm
Elevation range   ?
Traverse range   360 degrees
Ammunition load
Main gun   ?
Machine guns   -
Mobility
Engine   Mitsubishi 10ZF diesel
Engine power   750 hp
Maximum road speed   53 km/h
Range   300 km
Maneuverability
Gradient   60%
Side slope   30%
Vertical step   1 m
Trench   2.7 m
Fording   1 m

comandantecarlos · « **Reply #7 on:** February 17, 2012, 07:42:30 AM »

The 23 mm is not sufficient because of the small range and destructive power. If someone wants this time the above idea into action ( 23 mm High Altitude Recoilless Multi Stage Gun ), then the ammo is too large and therefore the rate of fire will be reduced. It seems at the moment, 30, 35 and 40 mm guns of the optimal solution. It is interesting that the 57mm anti-aircraft guns forgotten how good they were of medium height. The development is stopped for some reason. The U.S. war in Vietnam, most configurations from 60 to 85 mm anti-aircraft guns shot down.

comandantecarlos · « **Reply #8 on:** February 17, 2012, 07:57:50 AM »

A very good and interesting site, lots of developments linked to the anti-aircraft gun.
http://www.quarry.nildram.co.uk/miltech.htm

Numbers · « **Reply #9 on:** February 18, 2012, 02:24:05 AM »

"Type 81 Self Propelled Anti Aircraft Gun"'s maximum slant range (altitude) is 4 km.

Altitude of proposed "23 mm High Altitude Recoilless Multi Stage Gun" is 20 kilometers.
4 kilometers altitude is not enough.

By the way as I already have mentioned increasing speed of round 5 times increases its penetration 25 times.
Explanation is Kinetic Energy formula.

Kinetic Energy = (mass x velocity^2)/2.
If Velocity is increased 5 times, Kinetic Energy will increase 5^2=25 times.

So I think 23 mm Sabot round with length of 1.2 meters (0.2 meters tungsten Sabot and 1 meter for 5 propellant
cases 0.2 meters each) will be perfect solution.

(See pictures of real Tank Sabots above, after my initial post).

comandantecarlos · « **Reply #10 on:** February 18, 2012, 02:00:04 PM »

Related articles:

http://www.quarry.nildram.co.uk/gustav.htm
The recoil-free ammunition is not proportional to the size of output. 950 m/s ,advanced weapons 1500 m/s
http://www.quarry.nildram.co.uk/gustavctg.jpg
THE SEARCH FOR HIGH VELOCITY:
http://www.quarry.nildram.co.uk/highvel.
30mm APFSDS cartridge : 1500 m/s no fragmentation
http://www.quarry.nildram.co.uk/30apfsds.jpg

comandantecarlos · « **Reply #11 on:** February 18, 2012, 03:48:10 PM »

Velocity table on page 37.38. Initial speed 1639 m / s. 6,100 m after 910 m / s. 4933 ms.=40mm APFSDS
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA381396
20mm ammo can in no way slant range 20 km

Numbers · « **Reply #12 on:** February 19, 2012, 06:41:46 AM »

Quote from: comandantecarlos on February 18, 2012, 02:00:04 PM

The recoil-free ammunition is not proportional to the size of output. 950 m/s, advanced weapons 1500 m/s.

But I proposed "23 mm High Altitude Recoilless Multi Stage Gun". 5 explosions, one after another of 5 propellant cases. And each explosion's gases are blown at the back of Recoiless design barrel. So the barrel is not damaged by excessive gas pressure.

I have already explained that the goal is to increase the velocity of round. Not its weight.
23 mm caliber tungsten round has perfect weight for 5,000 m/s velocity. With such high velocity increase in round's weight is not necessary.

23 mm round with 5,000 m/s velocity can achieve 20 kilometers altitude.

And "23 mm High Altitude Recoilless Multi Stage Gun" design is not "Telescopic" design.
It is normal looking ZU-23-2 with 6 meters length linear Recoiless barrel (see below).

jfb · « **Reply #13 on:** February 19, 2012, 07:39:49 PM »

"Also for gun round to reach 20 kilometers altitude it is necessary to increase its velocity. If we increase velocity of ZU-23-2 round five times (from 970 m/s to 5,000 m/s) it will reach 20 kilometers altitude."
One of the reasons why no country has tried that in the past 50 years is air friction. The air resistance is proportional to the square of the speed. For an initial speed of 5,000 m/s you would need an initial force several times larger, but the air resistance would be:
RA = - rCdA(v)2/2
Where A is the surface area of the bullet and Cd the coefficient drag., r the density of air and v the speed, v2 the speed square.
It seems that when the bullets is shot Cd is minimized because the bullet is spinning, but Cd increases sometimes after.
It's hard to know in advance Cd, but lets take an hypothetical case where you fire a bullet at 1,000 m/sec and it is slowed down to 850 m/sec after 2 seconds, in the second case you shoot a bullet at 5,000 m/sec and it is slowed down to 1,500 m/sec after 2 seconds, is it such a big gain? You would still have a short range gun, regardless of the initial speed.
Furthermore the temperature of the bullet would raise a lot too.

jfb · « **Reply #14 on:** February 19, 2012, 09:53:20 PM »

I forgot another problem with this, the accuracy of the radar. I saw some specifications where it was given as an angle in mRad (milli radians), but the more you go far the less you have chances to hit your target with a bullet. If the error margin grows like the surface of a sphere (pi * r2) so like the square of the distance you face a much bigger problem 20 km away than 4 km away. Except for high power lasers, which are develloped only by super powers with more or less success, I don't see how you can get a target so far away except with a missile.

farbod · « **Reply #15 on:** February 19, 2012, 10:47:50 PM »

jfb the surface area of a sphere is 4pi^2.

Ich · « **Reply #16 on:** February 19, 2012, 10:59:29 PM »

Maybe he lost the "4" as you lost the "r" $:-\$

Numbers · « **Reply #17 on:** February 20, 2012, 04:25:04 AM »

Quote from: jfb on February 19, 2012, 07:39:49 PM

Air Resistance would be:
RA = - (rCdA(v)^2)/2

Where A is the surface area of the bullet and Cd the coefficient drag, r the density of air and v the speed, v^2 the speed square.

or RA = - (r x Cd x (Pi x r^2) x V^2)/2

Area of circular bullet = Pi x r^2

So if we increase velocity 5 times then RA will be increased by 25 times.
And if we decrease radius 5 times then RA will be decreased by 25 times.

KS-19 (Sair) round is 100 mm in diameter and 50 mm in radius.
While "23 mm High Altitude Recoilless Multi Stage Gun" round is 23 mm in diameter and 11.5 mm in radius.

KS-19 (Sair) altitude is 12,700 m.

11.5 mm (radius) round is 5 times less than 50 mm (radius) round.

So if round velocity is increased 5 times and radius of round is decreased 5 times we have
no overall change in Air Resistance.

Then 23 mm KS-19 (Sair) round is not slowed by Air Resistance as increase in velocity is off set
by decrease in round radius. Or more specifically round's radius is decreased 5 times to decrease round's
Area 25 times.

So instead of KS-19 altitude of 12,700 meters, 23 mm round can reach latitude of 20,000 meters.
Assuming of course it is "23 mm High Altitude Recoilless Multi Stage Gun" design.

jfb, you have forgot about decrease in round radius that off sets increase in velocity.

Numbers · « **Reply #18 on:** February 20, 2012, 04:36:59 AM »

Quote from: jfb on February 19, 2012, 09:53:20 PM

Except for high power lasers, which are develloped only by super powers with more or less success, I don't see how you can get a target so far away except with a missile.

Simple. If "23 mm High Altitude Recoilless Multi Stage Gun" round can reach 20 kilometers altitude it will do it in 4 seconds (speed of round is 5 kilometers/second).

Then gunner should aim at Aircraft flying at altitude 20 kilometers with preemption. And rounds are tracer rounds so gunner can see rounds flying near the target. Gunner can change his aim by looking at distance between target and tracer rounds that fly near target.

Ich · « **Reply #19 on:** February 20, 2012, 06:18:15 AM »

So if this works maybe you can take out a M1 Abrams with this 23 mm "FlaK" due to the kinetic energie of the rounds. The kinetic energie of one bullet will be 2,5 MJ while the energie of the kinetic rounds fired by the Leopard A6 have 13 MJ ^^

Numbers · « **Reply #20 on:** February 20, 2012, 06:27:51 AM »

Quote from: Ich on February 20, 2012, 06:18:15 AM

So if this works maybe you can take out a M1 Abrams with this 23 mm "FlaK" due to the kinetic energie of the rounds. The kinetic energie of one bullet will be 2,5 MJ while the energie of the kinetic rounds fired by the Leopard A6 have 13 MJ ^^

Yes, except "23 mm High Altitude Recoilless Multi Stage Gun" was proposed to take out 20 kilometers altitude Aircrafts. Using Nightvision and Infrared zoomable optics. And tracer rounds.

jfb · « **Reply #21 on:** February 20, 2012, 02:21:01 PM »

When a concept hasn't been tried by any country over several decades I tend to be mefiant because there is often one or several reasons. I agree with you that reducing the cross section (the radius) would reduce air resistance, which gives a very long bullet. How such a bullet behaves aerodynamically is another issue. You can take a look at this page
http://en.wikipedia.org/wiki/External_ballistics which describes the complexity of the problem. Theorical models that give the friction, drag coefficient exists, but often they have to readjust them in a real situation. In the section "The transonic problem" it explains how the stability of the bullet can be affected,

Quote

the bullets starts to exhibit an unwanted precession or coning motion that, if not damped out, can eventually end in uncontrollable tumbling along the length axis).

Your bullet is a very long needle, shot with an angle in general, and lateral winds could have a different effect, even if it's possible on the paper to give it an initial speed of 8 km/sec and expect the speed to drop to 3 km/sec after 3 seconds, your bullets would need the proper fins to be stable.
The other aspect that I mentioned is the accuracy of the radar, in addition to the accuracy of the bullet. If you have an error margin of +/- 1 milli radian and let say that your target is anywhere on a curved surface of 50 m2 at 4 km of distance, it could be anywhere on a curved survace of 200 m2 at a distance of 8 km ( the radius double, the new surface is the square of it) and a curved surface of 800 m2 at an altitude of 16 km. So if your target is 10 m2 you have 20% chances (10 m2/ 50 m2) to hit it at an altitude of 4 km and 1,25% chances for an altitude of 16 km. And this doesn't take in account the error margin for the depth, because if the plane is moving fast and your radar miscalculate the altitude by 20m, it is no longer there when your bullet reach the correct altitude.
Generally aircrafts can detect when your radar lock them (fire control mode rather than detection mode) and they change their trajectory. The biggest advantage of a missile is that you can maintain a nearly constant speed, so the aerodynamic behavior is easier to predict, plus the fact that ist large enough to integrate a small radar in the nose. The big equipement on the ground guide the missile for most of the trajectory and the small radar can be activated when it is close enough from the target.

jfb · « **Reply #22 on:** February 20, 2012, 04:56:39 PM »

@Numbers:

Quote

Then gunner should aim at Aircraft flying at altitude 20 kilometers with preemption.

This and the fact that you mention tracers to allow the gunner to see the target, I have to disagree on this, the new systems made by Iran are using a computer that points to the target according to the radar output.
My eyes can't see an aircraft 20 km away, much less a tracer.
The Saer and the Samavat (35 mm) both use a computer to change the direction of the tube. A human being is less accurate. I don't know if cheap UAV equipped with air-air missiles or small calibers would be better but my guess is that such an assesment was performed in many countries before and they judged that the probability to shoot the target at such a distance with a fast bullet was too weak, so they went for ground-air missiles.

Numbers · « **Reply #23 on:** February 21, 2012, 05:34:37 AM »

Quote from: jfb on February 20, 2012, 02:21:01 PM

When a concept hasn't been tried by any country over several decades I tend to be mefiant because there is often one or several reasons. I agree with you that reducing the cross section (the radius) would reduce air resistance, which gives a very long bullet. How such a bullet behaves aerodynamically is another issue.

ZU-23-2 bullet has dimensions of 23×152 mm. Bullet is shot, only 152 millimeters. So problem of side drag is also solved.

Remember that in "23 mm High Altitude Recoilless Multi Stage Gun" only velocity of 23 mm bullet is increased to 5,000 meters per second. And 23×152 mm bullet is made of tungsten.

Numbers · « **Reply #24 on:** February 21, 2012, 05:48:39 AM »

Quote from: jfb on February 20, 2012, 04:56:39 PM

This and the fact that you mention tracers to allow the gunner to see the target, I have to disagree on this, the new systems made by Iran are using a computer that points to the target according to the radar output.
My eyes can't see an aircraft 20 km away, much less a tracer.
The Saer and the Samavat (35 mm) both use a computer to change the direction of the tube. A human being is less accurate.

Well, Phased Array Radar like the one used on Iranian Mesbah can be used on "23 mm High Altitude Recoilless Multi Stage Gun".
With the same accuracy.

Except Phased Array Radars are very accurate due to combining of Radar radiation into one scanning beam.

Tracers can also be used, especially with Nightvision and Infrared zoomable optics. And computer that predicts target's position based on target's picture in Nightvision and Infrared spectrum. With or without human operator input.

See pictures of Mesbah Phased Array Radar below.