Best dogfight gun?

On Fri, 05 Dec 2003 07:45:39 GMT, Chad Irby wrote:


Whats the avarage gun burst time in a dogfight...

Whatever it is, you're going to have to hold the trigger down for over
three times that to get the same amount of fire downrange.

Given the that the designer of the mig-29 is on record as saying that he
should have halved the number of rounds carried for its gsh-30L. Tony
Williams has a table on his website which details why a single barrelled
cannon will get there 1st with the mostest when compared to a gatling.



greg

--
In the beginning. Back in nineteen fifty-five
Man didn’t know about a rock ’n’ roll show
And all that jive.

Greg Hennessy wrote in message . ..
On Fri, 05 Dec 2003 07:45:39 GMT, Chad Irby wrote:


Whats the avarage gun burst time in a dogfight...

Whatever it is, you're going to have to hold the trigger down for over
three times that to get the same amount of fire downrange.

Given the that the designer of the mig-29 is on record as saying that he
should have halved the number of rounds carried for its gsh-30L. Tony
Williams has a table on his website which details why a single barrelled
cannon will get there 1st with the mostest when compared to a gatling.

This is from 'Flying Guns: the Modern Era' by Emmanuel Gustin and
myself, due to be published in March next year:

"There are three competing philosophies when it comes to gun design
for fighter aircraft. One is the US rotary; fast-firing but (to date)
only 20 mm in calibre, and a very bulky system. The second is the West
European preference for a 27 – 30 mm revolver cannon; no lighter, but
slimmer and hard-hitting. The third is represented by the Russian GSh
301; a minimalist gun but with an equally hard-hitting performance.
The twin-barrel GSh-30 also deserves mention, even though it has not
been used in fighter aircraft. It weighs about the same as the western
guns at 105 kg, but fires powerful 30 mm ammunition at up to 3,000
rpm.

The merits of the 27 mm BK 27 revolver as opposed to the M61A1 can be
clearly demonstrated. In the first 0.5 seconds of firing, the M61
fires 18 rounds massing 1.8 kg in total weight of projectiles, the BK
27 fires 14 rounds weighing 3.7 kg. In the first full second, the M61
fires 68 rounds weighing 6.9 kg, the BK 27 fires 28 rounds weighing
7.4 kg. In weight of fire, as well as the destructiveness of the
individual projectiles, the Mauser clearly has an advantage, albeit
one that the faster-accelerating M61A2 reduces somewhat. This is
significant in that dogfights frequently permit only the briefest of
firing opportunities, and although a skilled pilot anticipating a
firing opportunity can 'spin up' a rotary in advance, such notice
cannot always be guaranteed.

The Mauser projectiles are also relatively heavier, resulting in a
sectional density (SD) of .507 compared to .363 for the 20 mm, which
means they will retain their initial velocity out to a greater range.
The 30 mm GSh-301 offers similar performance to the BK 27 with about
half the weight. On paper, this is an impressive fighter gun, although
its maintenance requirements have been criticised. The choice of a
heavy projectile (with an SD of .616) at a moderate velocity for the
Russian 30 mm guns implies that ground attack has a higher priority
than aerial combat in Russian thinking.

The ideal gun for aerial combat will of course combine the best of all
worlds: a high rate of fire, instantly achieved; a high muzzle
velocity to minimise flight time; and projectiles large enough to
inflict serious damage with each hit (requiring a calibre in the 25 –
30 mm range). The optimum weapon among those currently developed may
well be the new GIAT 30M791 revolver, although its weight means that
two GSh 301s (or a GSh-30) could be carried instead, with a higher
rate of fire. If the Russian guns' 30 x 165 ammunition were loaded
with lighter projectiles for a higher muzzle velocity, its aerial
combat capabilities would be improved, at the cost of some loss of
ground attack effectiveness."

Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk
Discussion forum at: http://forums.delphiforums.com/autogun/messages/

"Tony Williams" wrote

The merits of the 27 mm BK 27 revolver as opposed to the M61A1 can be
clearly demonstrated. In the first 0.5 seconds of firing, the M61
fires 18 rounds massing 1.8 kg in total weight of projectiles, the BK
27 fires 14 rounds weighing 3.7 kg. In the first full second, the M61
fires 68 rounds weighing 6.9 kg, the BK 27 fires 28 rounds weighing
7.4 kg. In weight of fire, as well as the destructiveness of the
individual projectiles, the Mauser clearly has an advantage, albeit
one that the faster-accelerating M61A2 reduces somewhat. This is
significant in that dogfights frequently permit only the briefest of
firing opportunities, and although a skilled pilot anticipating a
firing opportunity can 'spin up' a rotary in advance, such notice
cannot always be guaranteed.

Tony, why have none of the Gatling guns been designed to be "armed" and spun
up with the ammunition feed disengaged and "fired" at full rate by engaging
the ammunition feed? It seems obvious enough. There are some obvious issues
in inertial loads in the ammunition train but a "burst's worth" of rounds
could be decoupled from the main ammo tank.

Paul F Austin wrote:
"Tony Williams" wrote

The merits of the 27 mm BK 27 revolver as opposed to the M61A1 can be
clearly demonstrated. In the first 0.5 seconds of firing, the M61
fires 18 rounds massing 1.8 kg in total weight of projectiles, the BK
27 fires 14 rounds weighing 3.7 kg. In the first full second, the M61
fires 68 rounds weighing 6.9 kg, the BK 27 fires 28 rounds weighing
7.4 kg. In weight of fire, as well as the destructiveness of the
individual projectiles, the Mauser clearly has an advantage, albeit
one that the faster-accelerating M61A2 reduces somewhat. This is
significant in that dogfights frequently permit only the briefest of
firing opportunities, and although a skilled pilot anticipating a
firing opportunity can 'spin up' a rotary in advance, such notice
cannot always be guaranteed.

Tony, why have none of the Gatling guns been designed to be "armed"
and spun up with the ammunition feed disengaged and "fired" at full
rate by engaging the ammunition feed? It seems obvious enough. There
are some obvious issues in inertial loads in the ammunition train but
a "burst's worth" of rounds could be decoupled from the main ammo
tank.

One thing I've not thought of before and that's the gyroscopic effects
of a fast rotating drum on the directional abilities of an aircraft ?
It can't be that much of course or it would not have been used at all. I
assume that the drum is relatively low mass ?


Richard.

On Sat, 6 Dec 2003 11:23:25 -0000, "Richard Brooks"
wrote:

Paul F Austin wrote:
"Tony Williams" wrote

The merits of the 27 mm BK 27 revolver as opposed to the M61A1 can be
clearly demonstrated. In the first 0.5 seconds of firing, the M61
fires 18 rounds massing 1.8 kg in total weight of projectiles, the BK
27 fires 14 rounds weighing 3.7 kg. In the first full second, the M61
fires 68 rounds weighing 6.9 kg, the BK 27 fires 28 rounds weighing
7.4 kg. In weight of fire, as well as the destructiveness of the
individual projectiles, the Mauser clearly has an advantage, albeit
one that the faster-accelerating M61A2 reduces somewhat. This is
significant in that dogfights frequently permit only the briefest of
firing opportunities, and although a skilled pilot anticipating a
firing opportunity can 'spin up' a rotary in advance, such notice
cannot always be guaranteed.

Tony, why have none of the Gatling guns been designed to be "armed"
and spun up with the ammunition feed disengaged and "fired" at full
rate by engaging the ammunition feed? It seems obvious enough. There
are some obvious issues in inertial loads in the ammunition train but
a "burst's worth" of rounds could be decoupled from the main ammo
tank.

One thing I've not thought of before and that's the gyroscopic effects
of a fast rotating drum on the directional abilities of an aircraft ?


Which brings up something I've always wondered. Why doesn't the
compressor and turbines of a jet engine have that effect but on a much
larger scale? I imagine the gyroscopic effects of the rotor in an
F110 on an F-16 would be nothing to sneeze at.




It can't be that much of course or it would not have been used at all. I
assume that the drum is relatively low mass ?

"Scott Ferrin" wrote in message
...
On Sat, 6 Dec 2003 11:23:25 -0000, "Richard Brooks"
wrote:



Which brings up something I've always wondered. Why doesn't the
compressor and turbines of a jet engine have that effect but on a much
larger scale? I imagine the gyroscopic effects of the rotor in an
F110 on an F-16 would be nothing to sneeze at.


For one thing the modern aircraft have a greater ratio of mass
of aircfraft as a whole to the engine. The PW-200 series
engine weighs in at around 3400lb or rather less that 10%
of the F-16's all up weight and only a fraction of that is rotating.

In contrast the engine of a Sopwith Camel weighed around
300 lbs and was ALL rotating when the aircraft all up weight
was less than 1000lbs.

Then again the control authority of modern aorcraft is higher
and the fly by wire control system can compensate for
gyroscopic forces rather better than a human being.

Keith

Keith Willshaw wrote:

"Scott Ferrin" wrote in message
...
On Sat, 6 Dec 2003 11:23:25 -0000, "Richard Brooks"
wrote:



Which brings up something I've always wondered. Why doesn't the
compressor and turbines of a jet engine have that effect but on a much
larger scale? I imagine the gyroscopic effects of the rotor in an
F110 on an F-16 would be nothing to sneeze at.

It can be a problem at very slow speeds, which is why the Pegasus engine in
the Harrier has its two spools (low and high pressure) counter-rotate.
Offhand, I can't remember if the F100 or F110 do as well, but then a/c like
the F-15 and F-16 are unlikely to spend much time slow enough for it to
matter (thrust-vectoring nozzles can help there). OTOH, the engines for the
F-35 probably have to counter-rotate.

Guy

In article ,
Keith Willshaw wrote:

Then again the control authority of modern aorcraft is higher
and the fly by wire control system can compensate for
gyroscopic forces rather better than a human being.

And assymetric recoil as well I assume, but I think I read
that test firing of the F-22's gun induced yaw, but little
enough that the pilot easily could compensate, which must
mean the FCS doesn't try to.
--
Urban Fredriksson http://www.canit.se/%7Egriffon/
Things that try to look like things often look more like
things than things do.

uk (Tony Williams)

snip

The merits of the 27 mm BK 27 revolver as opposed to the M61A1 can be
clearly demonstrated. In the first 0.5 seconds of firing, the M61
fires 18 rounds massing 1.8 kg in total weight of projectiles, the BK
27 fires 14 rounds weighing 3.7 kg. In the first full second, the M61
fires 68 rounds weighing 6.9 kg, the BK 27 fires 28 rounds weighing
7.4 kg. In weight of fire, as well as the destructiveness of the
individual projectiles, the Mauser clearly has an advantage, albeit
one that the faster-accelerating M61A2 reduces somewhat.

You shoot your own argument down. The BK27's projectile weight has no effect if
you don't actually strike the target. A 27 mm projectile that misses is not as
efective a 20 mm projectile that hits. In your example above the M61 has more
projectiles in the air at any given time than the BK27 giving a greater
probable hit with the M61.

Dan, U. S. Air Force, retired

In article ,
(Tony Williams) wrote:

The merits of the 27 mm BK 27 revolver as opposed to the M61A1 can be
clearly demonstrated. In the first 0.5 seconds of firing, the M61
fires 18 rounds massing 1.8 kg in total weight of projectiles, the BK
27 fires 14 rounds weighing 3.7 kg. In the first full second, the M61
fires 68 rounds weighing 6.9 kg, the BK 27 fires 28 rounds weighing
7.4 kg. In weight of fire, as well as the destructiveness of the
individual projectiles, the Mauser clearly has an advantage, albeit
one that the faster-accelerating M61A2 reduces somewhat. This is
significant in that dogfights frequently permit only the briefest of
firing opportunities, and although a skilled pilot anticipating a
firing opportunity can 'spin up' a rotary in advance, such notice
cannot always be guaranteed.

This skips one of the big advantages of a faster-firing gun.

When your target is crossing your sights, having twice the "cycle time"
puts bullets into the other plane twice as often. Skeet shooters use
shotguns instead of rifles. Weight of fire is nice, but heavier bullets
don't help much if the other plane gets missed altogether due to not
having enough of them on target.

Note also that the Mauser install in the Typhoon holds about 1/3 of the
ammo that the M61A2 in the Raptor will, so things come out pretty even
as far as throw weight and firing time, with a small advantage for the
Mauser in promptness, and a small one the other way for the M61A2 in
overall bullet weight in the aircraft (eight one-second bursts versus
five for the Mauser).

Now, if you're shooting at tanks and other ground vehicles, that Mauser
sure has an advantage, but the F-22 probably won't be spending a lot of
time at that...

(The British Typhoons aren't even going to have guns in them after the
first tranche, BTW. Bad idea.)

--
cirby at cfl.rr.com

Remember: Objects in rearview mirror may be hallucinations.
Slam on brakes accordingly.