Author Topic: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?  (Read 6514 times)

Offline jcf

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Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #25 on: August 09, 2018, 12:51:31 PM »
All this talk of gunships has me Imagineering a Blackburn Beverly with a 25pdr, a 6pdr Molins gun and either a Vickers 40mm or 2pdr pom pom.

Then of course there would be the follow on Argosy and maybe Belfast  ;)

Surely a Beverly would simply have a two deck broadside of 2pdr pom-poms.  ;D
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Offline apophenia

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Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #26 on: August 10, 2018, 03:26:26 AM »
@ M.A.D. - Have you given any consideration to a smaller caliber weapon? ...

What about RO's L23A1  low velocity 76 mm gun from the M113? The vertical-sliding breech-block is semi-automatic (cammed to open on run-out). Maybe add a muzzle brake?

Specs for the 'Pumpkin Launcher' follow:

LENGTH: ordnance 2062 mm; recoil 280 mm
WEIGHT (complete) 150.59 kg
RATE OF FIRE 6 rds/min
RANGE: max. direct 2200 m; max. indirect 5000 m
BARREL LIFE 4750 EFC
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Offline Rickshaw

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Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #27 on: August 10, 2018, 08:44:24 PM »
@ M.A.D. - Have you given any consideration to a smaller caliber weapon? ...

What about RO's L23A1  low velocity 76 mm gun from the M113? The vertical-sliding breech-block is semi-automatic (cammed to open on run-out). Maybe add a muzzle brake?

Specs for the 'Pumpkin Launcher' follow:

LENGTH: ordnance 2062 mm; recoil 280 mm
WEIGHT (complete) 150.59 kg
RATE OF FIRE 6 rds/min
RANGE: max. direct 2200 m; max. indirect 5000 m
BARREL LIFE 4750 EFC

I think you'll find the L23a1 comes originally from the CVR(T) Scorpion light tank.  It is a light weight design, hence the rather short barrel life of only 4750 rounds.  It has a muzzle velocity of 1542m/s. 

Offline apophenia

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Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #28 on: August 12, 2018, 04:17:07 AM »
I think you'll find the L23a1 comes originally from the CVR(T) Scorpion light tank.  It is a light weight design, hence the rather short barrel life of only 4750 rounds.  It has a muzzle velocity of 1542m/s.

Indeed. I mentioned the M113 ROF only for its Oz-relevance. The L23A1's light weight seems like an advantage in a gunship installation. Short barrel life, not so much. I'm not sure about muzzle velocity. Does firing downward obviate the problem of low mv for the 'Pumpkin Launcher' ?
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Offline Rickshaw

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Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #29 on: August 12, 2018, 04:35:07 PM »
I think you'll find the L23a1 comes originally from the CVR(T) Scorpion light tank.  It is a light weight design, hence the rather short barrel life of only 4750 rounds.  It has a muzzle velocity of 1542m/s.

Indeed. I mentioned the M113 ROF only for its Oz-relevance. The L23A1's light weight seems like an advantage in a gunship installation. Short barrel life, not so much. I'm not sure about muzzle velocity. Does firing downward obviate the problem of low mv for the 'Pumpkin Launcher' ?

Firing "downhill" ensures that range isn't a problem, I'm sure, despite it's low muzzle velocity.  As it fires HESH or HEAT rounds, it's armour piercing ability wouldn't be affected either.   The life for the barrel might be a bit more of a problem, needing to be changed after every 5-10 missions.

Having seen the M113 FSV fire at the P&EE range against a variety of targets, it was pretty much a pipsqueak compared to the Leopard along side it which also performed for us visitors.  The SPLINTEX round was the most spectacular, fired against a large, 20 foot high earthen wall, dividing the firing bays from one another at about 25 metres range.   Watching all the impacts across quite a wide arc was sobering to say the least.

Depending on the size and strength of the airframe, the 76mm L23a1 would be a bit light weight for most aircraft.   A 75mm tank gun, a'la WWII would be more effective.  A 90mm MECAR or similar low recoil weapon would be ideal, though.

Offline tankmodeler

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Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #30 on: August 14, 2018, 01:04:33 AM »
It has a muzzle velocity of 1542m/s.

That muzzle velocity's a tad high, no?  ;D Looks like 534 m/s or 1735 ft/s is a better number.

And 4700 rounds of barrel life isn't horrible. Even if you fire a hundred rounds a mission, that's 47 missions and I can't see them firing a hundred rounds on average, would they?

Just sayin'...

Paul

Offline apophenia

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Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #31 on: August 14, 2018, 06:27:41 AM »
That muzzle velocity's a tad high, no?  ;D Looks like 534 m/s or 1735 ft/s is a better number.


I note that www.scorpiontank.co.uk gives your more realistic 534 m/s. I liked Rickshaw's suggestion of a 90mm Mecar ... but I guess we need a timeframe from M.A.D.
« Last Edit: August 18, 2018, 07:04:19 AM by apophenia »
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Offline Rickshaw

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Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #32 on: August 14, 2018, 01:05:41 PM »
It has a muzzle velocity of 1542m/s.

That muzzle velocity's a tad high, no?  ;D Looks like 534 m/s or 1735 ft/s is a better number.

Correct.  My error.  That was the APDS round for the L11 120mm tank gun, which is also designated L23a1.

Offline tankmodeler

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Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #33 on: August 14, 2018, 11:22:37 PM »
Correct.  My error.  That was the APDS round for the L11 120mm tank gun, which is also designated L23a1.
Wow, that's a spectacularly high number for an APDS (probably FS-T as well) round. I believe it, but wow, that's fast. Mach 4+. Almost, technically, hypersonic.

Cool info, ta.

Paul

Online M.A.D

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Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #34 on: November 15, 2019, 12:06:38 PM »
My sincere apologies for my lack of participation on this means 😞

In my long overdue response to this topic, after time to deliberate, Rickshaw and apophenia I'm liking your notion of the MECAR 90/28 mm gun 😯, especially seeing that in my Alternative ADF ORBAT, I have the Australian Army using Canon Antitank d’Infanterie 90 mm (CATI 90) from 1954 to ~1962. In which case I could have the realistic case of the MECAR 90/28 mm guns being removed from the chassis and put into 'War Stocks', and then in 196?, with the operational need of the DHC-4T Caribou gunships, some of these MECAR 90/28 mm guns could be utilised 😯

Now from what I've been able to find, "the total weight of the MECAR 90/28 mm gun is 274 kg and featured a hydraulic recoil system. The gun had a recoil of 2500 kg and a recoil length of 40 cm, both of which are relatively low. The breech mechanism was semi-automatically cam-operated, the cases were ejected automatically."

So with the forums knowledge, do we think this MECAR 90/28 mm gun would be viable in the DHC-4T Caribou gunship? Maybe a low recoil cradle modelled on that of 105mm howitzer employed on the AC-130 could be utilised, to save cost and time......

(Please note, I also envisage the Australian Army employing the 90mm in the fire-support role, as opposed to the 76mm L23A1in my Alternative ADF ORBAT, so ammunition comparability will be there - especially as I picture these DHC-4T/DHC-5 gunships being versed in forward operation with Army units as part of their SOP's....)

Please note, someone from another forum sent me this:

"The 90mm/46 KEnerga, sometimes marketed as the Cockerill Mk8,  was offered as a towed gun in the late 80s/early 90s. KEnerga a confusing program, I believe initially developed by MECAR but later marketed in a collaboration with Cockerill. MECAR had previously sold a towed version of its 90mm/28 light gun as well."

So I'm wondering if the RAAF would be able to incorporate this '90mm/46 KEnerga' or the 'towed version of its 90mm/28 light gun' for the larger, more powerful DHC-5 Buffalo gunship.

(Would love to know more about this '90mm/46 KEnerga' or the 'towed version of the 90mm/28 light gun', if anyone, with the exception of GTX who has already sent me what he's got 😯)

M.A.D
« Last Edit: November 17, 2019, 04:49:13 AM by M.A.D »

Offline tankmodeler

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Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #35 on: November 26, 2019, 11:46:00 PM »
So with the forums knowledge, do we think this MECAR 90/28 mm gun would be viable in the DHC-4T Caribou gunship? Maybe a low recoil cradle modelled on that of 105mm howitzer employed on the AC-130 could be utilised, to save cost and time.....
Fundamentally, the 90mm should be suitable in a 'Bou. There may, indeed need to be a secondary or modified recoil system to lessen the recoil impulse as a 2500 kg sideload on the fuselage may be tough on the airframe and a bit of a b!tch from the aircraft control POV if applied as quickly as an artillery piece generates it. Spreading it out even a little bit makes a huge difference to both the structure and the flying characteristics.

The 'Bou is a MUCH smaller aircraft than an C-130 and 2500kg is 2/3 of it's max rated payload, so there would probably be a need to reinforce the structure of the airframe as well as possible limits on what other weapons could be carried as well as limits on ammo and sensors.

The C-130 can handle on the order of 15-19 metric tons (depending on specific version) whereas the 'Bou can only manage 3.6mt, just a bit more than a DC-3. It's an indicator of how careful one might have to be with installing heavy weapons.

HTH

Paul

Online M.A.D

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Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #36 on: November 30, 2019, 01:18:00 PM »
Thanks Paul (tankmodeler), very informative feedback!!👍


MAD