autogun

Military Guns and Ammunition

Hosted by autogun

This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.

  • 3218
    MEMBERS
  • 182853
    MESSAGES
  • 2
    POSTS TODAY

Discussions

The Foresight War Revisited: AFVs   Novel: The Foresight War

Started 16-Feb by autogun; 18054 views.
larrikin2

From: larrikin2

24-Mar

It wasn't an internal mantlet as such, it was a ball mount, which gave it a +15/-10 elevation range, and probably a reasonably decent lateral movement as well.

Red7272

From: Red7272

24-Mar

larrikin2 said:

It wasn't an internal mantlet as such, it was a ball mount, which gave it a +15/-10 elevation range, and probably a reasonably decent lateral movement as well.

And guaranteed the penetration of any round that hit that 2 foot circle. Read up on the NA 75s for what people actually thought of internal mantlets on the Churchill. 

larrikin2

From: larrikin2

24-Mar

Oh, I know about the problems of internal mantlets.  They were the bane of British tank design and users.

The Tortoise also used a ball mount, but it had a bloody great amoured collar attached to the barrel that protected the gap in the amour needed to get the amount of movement out of the gun.

In reply toRe: msg 144
Red7272

From: Red7272

10-Apr

Back to engines.

Napier and Lion have to be the tank engine and engine makers of choice. If the Merlin can be turned into the Meteor then the Lion can be turned into a tank engine. There is enough time and resources available within Napier to fix that issue and get production of the engine started.  

Ethanol upping the octane to 95 or 100 seems like a too good to be true solution for the period and well worth standardising it as the fuel type used by the UK military pre-war. 
It would probably benefit the nazis more that the Brits but then they have their own traveller so that should not really be a consideration. 

The construction of the lion with individual cylinders makes it an excellent candidate for the various sub engines needed for the various pre war contraptions like Crusader. As noted previously I think Crusader should be a utility hull for mounting engineering and SP artillery on and not a tank in it's own right, that should be left to the Churchill. The British army will need the experience with heavier tanks from a logistical and strategic mobility point of view. There is no reason why the Churchill can't be the British T-34 and grow from 24 to 30 tonnes over the war period. 

that potential is also needed because the other traveller will revamp their tank production and their armour can be expected to be much better armoured and more effective than historically. 

autogun

From: autogun

10-Apr

Red7272 said:

Back to engines.

On the face of it, the Lion should be an ideal choice: it's compact (great for rear-mounting), about the right power, and very reliable. However, somewhere in these posts I recall some specific issues being raised against the Lion in a tank. One was to do with electrics and seemed solvable without much trouble, but the other was do with ignition problems (knocking, IIRC) when using low-octane petrol, even with very low compression ratios. I don't know how solvable that would be (other than by using higher-octane petrol, of course).

Which again raises the question of fuel octanes. How easy is it to make (or buy, in the case of the UK) higher-octane petrols? What logistic problems would it cause if the tanks needed a higher grade of petrol that the other vehicles' engines can happily cope with? When operating abroad, how readily available would higher-octane petrols be at commercial filling stations at that time?

I think we should start putting some octane numbers on all this, to get a feel for the problems.

hobbes154

From: hobbes154

10-Apr

autogun said...

I think we should start putting some octane numbers on all this, to get a feel for the problems.

See discussion herehere and here. Basically:

  • Lion was tested vs Liberty on 65 octane in 1937. Lion had severe detonation even using a lower compression ratio than the Liberty (this suggests the Lion's ignition was harder to adjust because it used magnetos).
  • Wartime supplies from the US were 80 octane - not sure exactly when that kicked in, at a guess 1940? Postwar pool petrol went down again.
  • Not sure exactly how low octane OTL Lion (or Meteor) could go but probably in the 70s?

I have no idea of the cost of raising the octane of pool petrol or the necessary engine modifications to run on either ethanol or lower octane, so seems safer not to rely on it.

Note the big attraction of the Lion was all the RAF surplus engines lying around, so any mods that make them unusable or expensive really spoil the idea. Otherwise what's the advantage over a Kestrel or Meteorite? 

In reply toRe: msg 148
hobbes154

From: hobbes154

10-Apr

More problems with the Lion, apparently:

BTW I spoke to someone who had looked into Napiers for a book (abandoned) on their aero engines and he tells me that they were selling Sea Lions late in the 1930s but made from old stock and new major parts manufacturing had long stopped by then. The surplus RAF ones were scrap price for a good reason as the RAF had cannibalised anything that would keep their Lions going as long as possible so they would need a lot of work to make them fit and there were not enough parts for that and those in hand at Napiers were earmarked to the Sea Lion programme. Napier, of course, would make new Lions for a big enough order but much machinery was already moved onto the Rapier/Dagger/Sabre work so would have to cover the cost of new machinery. You could have spent the entire tank budget on just the engines.
 

larrikin2

From: larrikin2

10-Apr

That would probably depend on when the decision was made more than anything else.

And that is interesting, and for our purposes, useful information, because everything else I've seen suggested that Napier were still making Lions possibly as late as 1940, but the refurbishing older ones with scrapped parts and from old stock puts a crimp in plans and suggestions.

Damn! relaxed

autogun

From: autogun

11-Apr

Well, that does help to explain why so little interest was shown in the Lion at a time when British tank designers were very keen to get hold of a decent engine!

Red7272

From: Red7272

11-Apr

Quite. It seems that an early meteor is the only option.   The Crusader should be the earliest tank and obviously needs the liberty. This could be replaced on later versions by a V6 meteor for commonality and improved reliability. The artillery platforms on the same chassis could follow Marder III route with the driver front, the engine middle and the fighting compartment rear or or just be a convectional tank layout with with a artillery piece in a taller turret. 

TOP