Author Topic: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?  (Read 1674 times)

Offline Rickshaw

  • "Of course, I could be talking out of my hat"
Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #15 on: August 02, 2018, 03:06:51 PM »
The difference between the two weapons (M101/M102 and M56) is slight, as far as muzzle velocity goes:

M56 - Muzzle velocity   416.0 m/s (1,360 ft/s)
M101 - Muzzle velocity   1,550 ft/s (472 m/s)
M102 - Muzzle velocity 494 metres per second (1,620 ft/s).

Essentially, where the M56 wins over the M101/M102 is in it's lightweight construction and ease of disassembly and reassembly for pack duties.   Where it loses in in it's durability, which is why the Australian Army replaced it's M56s in RVN after about two years use with M101s.   While not a worry for airborne use, it's lack of wheel bearings on the ground mount prevent it being towed anywhere far or fast.

The M56 would require modification for extended use.  It's mount and it's tube would require "beefing up" and so would it's breech assembly.

Interesting discussion here, BTW, about the 105mm's recoil on the AC-130.
« Last Edit: August 02, 2018, 03:10:08 PM by Rickshaw »

Offline M.A.D

  • Also likes a bit of arse...
  • Wrote a great story about a Christmas Air Battle
Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #16 on: August 02, 2018, 05:57:59 PM »
Thank you once again Rickshaw.
I was aware of the OTO-Melara Mod 56 105 mm pack howitzer shortcomings, in terms of solidness and wear due to its lightweight principle and construction, but envisaged it firing far less in its airborne application.
Perhaps, ideally, I need a variant of the XM204 105mm Soft Recoil Howitzer!!😮😜
https://youtu.be/yDQDJnUJyl8, which would eleviate much of the concerns of recoil and stress loads on the aircraft!

P.S. that article re the employment of rails to guide and obsorb the M102's recoil in the AC-130 was very interesting!!



M.A.D
« Last Edit: August 02, 2018, 06:00:24 PM by M.A.D »

Offline tankmodeler

  • Wisely picking parts of the real universe 2 ignore
Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #17 on: August 02, 2018, 09:32:35 PM »
Rickshaw's points are very valid, I was just imagining you didn't want to redesign the recuperator system for this use. If that's on the table., then yeah, it could certainly work. And, yeah, the Spectre 105s are certainly not firing on anything like full charge. I'm pretty sure the targets are seldom more than 4-5 km away and a 105 could probably hit that, firing downhill as it is, with the primer charge alone. :D

Paul

Offline Old Wombat

  • "We'll see when I've finished whether I'm showing off or simply embarrassing myself."
  • "Define 'interesting'?"
Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #18 on: August 03, 2018, 12:13:48 AM »
I'm pretty sure the targets are seldom more than 4-5 km away and a 105 could probably hit that, firing downhill as it is, with the primer charge alone. :D


Most targets would be in 20mm range, so all weapons could be brought to bear (or 25mm for AC-130U Spooky II, or 30mm for AC-130W Stinger II & AC-130J Ghostrider variants).

The Wikipedia article is pretty good:
https://en.wikipedia.org/wiki/Lockheed_AC-130

This The Drive/The Warzone article is pretty good too but has the bonus of having a 40sec clip of the 105mm being charge tested, including an internal shot of the recoil, about half-way down the page:
http://www.thedrive.com/the-war-zone/9940/the-usaf-finally-gives-its-ac-130w-gunship-the-big-gun-it-desperately-needs
"This is the Captain. We have a little problem with our engine sequence, so we may experience some slight turbulence and, ah, explode."

Offline tankmodeler

  • Wisely picking parts of the real universe 2 ignore
Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #19 on: August 03, 2018, 03:43:39 AM »
I thought that one of the reasons that the 105 and 40mm guns were carried is the ability to get a tad further away from MANPADs on the ground. Yes, they provide a much bigger punch than the Vulcans or miniguns, but I had read somewhere (lost in the mists of time, unfortunately) that the reason to step up to the 40 and then 105 was to be able to step back from targets that might be better defended.

Could be wrong, of course. Frequently am.

Paul

Offline Rickshaw

  • "Of course, I could be talking out of my hat"
Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #20 on: August 03, 2018, 04:00:42 PM »
One of the problems with using aircraft "gunships" is that with the invention of MANPADS, the targets are able to defend themselves from the attacking aircraft much more easily.   The reason why the calibre of weapons has increased over the decades is because of their increased range, rather than necessarily their increased effectiveness.  The use of initially 7.62mm miniguns, then 20mm Vulcans, 25mm Rotary Cannon, 40mm Bofors and then 105mm guns was to put the aircraft at much greater range from their targets.   

With the need to switch to night operations a final way of preventing them from being shot down.   The operational limits on their use has meant that you need near total dominance of aerial superiority and usually night operations to make them effective.   Only the USAF attacking insurgents in Afghanistan/Iraq/Syria can guarantee both conditions, which is why they tend to be rather limited in their utility.

So, unless your user can guarantee near total air dominance and/or only night operations, your gunship isn't going to be of much use.   The day of the gunship is nearly over.   Soon, we will see transport aircraft armed completely with longer ranged missiles.  Roll on the "Arsenal Ship".  ;)

Offline Volkodav

  • Counts rivits with his abacus...
  • Much older now...but procrastinating about it
Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #21 on: August 03, 2018, 06:10:25 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  ;)

Offline Old Wombat

  • "We'll see when I've finished whether I'm showing off or simply embarrassing myself."
  • "Define 'interesting'?"
Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #22 on: August 03, 2018, 07:19:54 PM »
The AC-130W came out with a 30mm auto-cannon & missiles, the 105mm has been re-introduced to improve the effectiveness of the aircraft.

So, the AC-130W now has a 30mm auto-cannon, a 105mm M102 howitzer and missiles.
"This is the Captain. We have a little problem with our engine sequence, so we may experience some slight turbulence and, ah, explode."

Offline M.A.D

  • Also likes a bit of arse...
  • Wrote a great story about a Christmas Air Battle
Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #23 on: August 03, 2018, 07:47:48 PM »

Could be wrong, of course. Frequently am.

Paul

Takes a real man to admit it! Good on ya mate 👍

M.A.D

Offline Jeffry Fontaine

  • Unaffiliated Independent Subversive...and the last person to go for a trip on a Mexicana dH Comet 4
  • Global Moderator
  • His stash is able to be seen from space...
    • SketchUp 3D Warehouse - My Digital Models
Re: Lockheed AC-130 & M102 105mm Howitzer Engineering question please?
« Reply #24 on: August 09, 2018, 10:32:28 AM »
@ M.A.D. - Have you given any consideration to a smaller caliber weapon?  Say something like the 6pdr/57mm gun?  If they could fit one in a Mosquito MkXVIII then I see no reason why it could not be made to fit inside of your project aircraft. 
"Every day we hear about new studies 'revealing' what should have been obvious to sentient beings for generations; 'Research shows wolverines don't like to be teased" -- Jonah Goldberg

Offline jcf

  • Global Moderator
  • Turn that Gila-copter down!
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
"Evil our grandsires were, our fathers worse;
And we, till now unmatched in ill,
Must leave successors more corrupted still."
Horace, 65BC - 8BC. Marsh translation.

Offline apophenia

  • Suffered two full days of rapid-fire hallucinations and yet had not a single usuable whif concept in the lot !?!
  • Patterns? What patterns?
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
Under investigation by the Committee of State Sanctioned Modelling, Alternative History and Tractor Carburettor Production for decadent counterrevolutionary behaviour.

Offline Rickshaw

  • "Of course, I could be talking out of my hat"
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

  • Suffered two full days of rapid-fire hallucinations and yet had not a single usuable whif concept in the lot !?!
  • Patterns? What patterns?
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' ?
Under investigation by the Committee of State Sanctioned Modelling, Alternative History and Tractor Carburettor Production for decadent counterrevolutionary behaviour.

Offline Rickshaw

  • "Of course, I could be talking out of my hat"
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.