Aircraft Launched Rockets and Unguided Rocket Projectiles

[kitnut617]

I've read in a number of books that a salvo of 60lb RP's was the equivalent of a 6" broadside.  There's a couple of photos in my books of Mosquito's trial fitted and tested with 11.75" Uncle Tom RP's, also got one photo of a SeaFang carrying them too.

[jcf]

The British 3" and 5" rocket designations actually refer to the diameter of the rocket motor/body,
the warheads were of varying diameters.
UK info (scroll down to ROCKETS):
http://web.ukonline.co.uk/stephen.johnson/arms/

ORDATA site on 3" rocket, 60 lb rocket (warhead was a modified 4.5" dia howitzer shell):
http://maic.jmu.edu/ordata/srdetaildesc.asp?ordid=4054

US 5-inch FFAR (3.5-inch motor/5-inch warhead); 5-inch HVAR:
http://www.designation-systems.net/dusrm/app4/5in-rockets.html

ORDATA  on the 11.75" 'Tiny Tim' (warhead was a modified 500-lb bomb):
http://maic.jmu.edu/ordata/srdetaildesc.asp?ordid=2985

[Cliffy B]

Anyone have any info on the USN 5" ATAR (Anti Tank Aerial Rocket)?  I've only found one photo of a Korean era Corsair carrying a load of them.  Warhead reminded me on a Soviet RPG.  I wonder if those could have been useful in the anti-shipping role?

[dogsbody]

As I remember reading it, the first British rockets were of 3" diameter because that was the largest size of die that could be used to extrude the cordite used as the propellent. The Americans had access to larger ( 5" ) extruders, which matched up better with the 5' warheads and produced a higher velocity projectile.

Others may have better info on the subject.

[jcf]

Anyone have any info on the USN 5" ATAR (Anti Tank Aerial Rocket)?  I've only found one photo of a Korean era Corsair carrying a load of them.  Warhead reminded me on a Soviet RPG.  I wonder if those could have been useful in the anti-shipping role?

6.5" ATAR aka NOTS RAM (a 6.5" warhead mounted to the 5" HVAR):
http://www.designation-systems.net/dusrm/app4/ram.html

http://www.allaircraftarcade.com/forum/viewtopic.php?p=213843&highlight=&sid=e580e1210dabf224c01db227010d1281
A forum posting that has photos and links, I've attached a diagram from a PDF linked in the post.

As to its usefulness in an anti-shipping role. Well, that depends on the target, with such a specialized
shaped charge warhead being kinda pointless against an unarmored vessel with HE and SAP being more effective.

[Cliffy B]

Does anyone know the armor penetration values of the standard HVAR vs the ATAR?  If they can punch through a few inches of armor then they'd be useful against ships.  Given their speed and range they could fairly useful not to mention very hard to shoot down.  I wonder if an armor-piercing Tiny Tim is feasible?  Could be the WWII equivalent to an unguided Harpoon.  These rockets would have a higher hit percentage then dive bombing I think.  I don't know, thoughts?

[tigercat]

From the Wiki article

Soon after some encouraging results from the initial deployment, trials of the weapon were conducted against targets representing U-Boats. It was discovered that if the rockets were fired at a shallow angle, near misses resulted in the rockets curving upwards in seawater and piercing the targets below the waterline.


So given sufficently large warheads a German Battleship could perhaps be holed under the waterline below it's armour belt and wher eit would be most vulnerable.

[Weaver]

Two problems I see:

1. Shaped Charged penetration depends on the diameter of the cone rather than the weight of explosives, so a warhead that could penetrate battleship levels of armour might end up unfeasably wide and draggy, even if the aircraft could carry the weight.

2. Shaped Charge penetration also critically depends on the warhead exploding at the correct distance from the armour for the focussing effect to work. I have the impression that a lot of battleship armour was in complicated schemes with feet of spacing between layers of hull and/or armour, and this might well dissipate the effect of a shaped charge: after all, spaced armour/standoff screens are a standard defence against shaped charges for armoured vehicles.

[dogsbody]

Two problems I see:

1. Shaped Charged penetration depends on the diameter of the cone rather than the weight of explosives, so a warhead that could penetrate battleship levels of armour might end up unfeasably wide and draggy, even if the aircraft could carry the weight.

2. Shaped Charge penetration also critically depends on the warhead exploding at the correct distance from the armour for the focussing effect to work. I have the impression that a lot of battleship armour was in complicated schemes with feet of spacing between layers of hull and/or armour, and this might well dissipate the effect of a shaped charge: after all, spaced armour/standoff screens are a standard defence against shaped charges for armoured vehicles.

The Ju 88 Mistel was to use a 6' diameter shaped charge against Royal Navy capital ships. That was the calculated diameter needed to take out a battleship. The nose probe was about the same length as the diameter, to achive maximum penetration.

[NARSES2]

As I remember reading it, the first British rockets were of 3" diameter because that was the largest size of die that could be used to extrude the cordite used as the propellent.

Correct sir.

[rickshaw]

As I remember reading it, the first British rockets were of 3" diameter because that was the largest size of die that could be used to extrude the cordite used as the propellent. The Americans had access to larger ( 5" ) extruders, which matched up better with the 5' warheads and produced a higher velocity projectile.

Others may have better info on the subject.

Only problem with that is that British rockets utilised three separate sticks of cordite as propellant, laid parallel,  with a space, roughly triangular between them.  They were square in section as well.  The reason why I know this is because I once read a very lengthy article on the problems they encountered with the uneven burning of the propellant.  It seems the problem was that as the propellant burnt, it set up a wave pattern in the exhaust that prevented it burning evenly and this in turn prevented it reaching the optimal range.   Their solution (arrived at after several months of research) was to switch to a single stick, with an internal cavity running the length of the stick in the shape of a equilateral cross which twisted along its whole length.   This prevented the wave pattern forming and ensured even burning.

[NARSES2]

Thanks for that Rickshaw. Explains the problems with the origional AA "Z" batteries, one of which was just down the road to where I now live.

Chris

[Weaver]

Thanks for that Rickshaw. Explains the problems with the origional AA "Z" batteries, one of which was just down the road to where I now live.

Chris

My dad served on Z-batteries for a while during the war. Don't know which ones though. He said that one of the major problems was the spent tubes coming down afterwards: they wern't something you wanted to get hit by!

[dogsbody]

As I remember reading it, the first British rockets were of 3" diameter because that was the largest size of die that could be used to extrude the cordite used as the propellent. The Americans had access to larger ( 5" ) extruders, which matched up better with the 5' warheads and produced a higher velocity projectile.

Others may have better info on the subject.

This is from the July 1985 issue of FlyPast magazine, the source of my statemene, above.

[dy031101]

Watched today's Dogfight episode on Rammkommando "ELBE"......

It claims that a Bf-109 stripped off its armours and almost all its guns can fly faster and higher than Allied escort fighters...... makes me wonder if a complete R4M system could still maintain most of that performance such that they could just have unloaded their rockets instead of having to go through the trouble of ramming the bombers.

Of course that might very well be my wishful thinking in that if widespread equipment of R4M was that easy, chances are it would have been done already......