General Discussions
This is the place to discuss general issues related to the U-boat war or the war at sea in WWII.
Re: Starshell
Posted by:
AL Wellman
()
Date: December 16, 2001 01:41AM
<HTML>Nathan -
I have a little information on the technical details of US starshells -- which I suppose might also apply to Commonwealth ammunition. Starshells were intended to silhouette the target rather than illuminate it in a conventional sense. The point of aim was therefore significantly different (high and behind the target) A magnesium flare in a steel cup was suspended from a steel wire. The wire attached to the bottom of the cup so the illumination was directed downward as the other end of the wire was suspended from a parachute. The flare and parachute were ejected from the base of the projectile by a time fuzed expulsion charge.
The expulsion charge was intended to ignite the flare and give it a backward velocity approximately equal to the forward velocity of the shell to minimize strain on the series of retarding parachutes which deployed prior to the main (sustaining) parachute. The retarding parachutes were attached along the wire between the flare and the main parachute. The wire was approximately 5 meters long for a 76mm gun and 12 meters long for a 127mm gun. The initial retarding parachute was approximately 1.5 projectile diameters and the sustaining parachute was approximately 8 projectile diameters.
The expulsion charge was seldom able to match the forward velocity, so the parachutes were often damaged by the shock of deployment or by the burning flare. The damaged chutes produced variable velocities and a significant percentage of starshells failed to provide useful illumination -- even in clear weather. A single gun firing both illumination and explosive shells approximately halved its effective rate of fire for explosive shells. (Although several explosive shells would typically be fired for each star shell, differing ammunition handling, fuze adjustment, and gun elevation for the star shells took disproportionately more time.) Ships with more than one gun would usually devote one gun to illumination fire and the others to high explosive shell. A group of ships might devote one ship to illumination fire while the others fired explosive shells.
A corvette's single gun might fire star shell exclusively in an attempt to illuminate an area suspected to hold a submarine (with the risk that firing in the wrong direction could silhouette the firing ship.) A ship's commanding officer usually reserves authority of ordering the guns to fire (since he bears responsibility for any damage inflicted on friendly forces), but the gunnery officer was sometimes delegated (or assumed at his own peril) limited authority in combat situations. Firing illuminating shell normally required authorization by the escort commander because it revealed the convoy location for much greater distances than it provided useful illumination.
The white light of starshells would damage night vision -- although not as much as you might expect because of the distance and potential for filtering through low clounds. It was often fired at times when night vision had already suffered from nearby explosions, fires, distress flares, and non-flashless gunpowder. Certain personnel might be designated to protect their vision from star shell exposure. =AL=</HTML>
I have a little information on the technical details of US starshells -- which I suppose might also apply to Commonwealth ammunition. Starshells were intended to silhouette the target rather than illuminate it in a conventional sense. The point of aim was therefore significantly different (high and behind the target) A magnesium flare in a steel cup was suspended from a steel wire. The wire attached to the bottom of the cup so the illumination was directed downward as the other end of the wire was suspended from a parachute. The flare and parachute were ejected from the base of the projectile by a time fuzed expulsion charge.
The expulsion charge was intended to ignite the flare and give it a backward velocity approximately equal to the forward velocity of the shell to minimize strain on the series of retarding parachutes which deployed prior to the main (sustaining) parachute. The retarding parachutes were attached along the wire between the flare and the main parachute. The wire was approximately 5 meters long for a 76mm gun and 12 meters long for a 127mm gun. The initial retarding parachute was approximately 1.5 projectile diameters and the sustaining parachute was approximately 8 projectile diameters.
The expulsion charge was seldom able to match the forward velocity, so the parachutes were often damaged by the shock of deployment or by the burning flare. The damaged chutes produced variable velocities and a significant percentage of starshells failed to provide useful illumination -- even in clear weather. A single gun firing both illumination and explosive shells approximately halved its effective rate of fire for explosive shells. (Although several explosive shells would typically be fired for each star shell, differing ammunition handling, fuze adjustment, and gun elevation for the star shells took disproportionately more time.) Ships with more than one gun would usually devote one gun to illumination fire and the others to high explosive shell. A group of ships might devote one ship to illumination fire while the others fired explosive shells.
A corvette's single gun might fire star shell exclusively in an attempt to illuminate an area suspected to hold a submarine (with the risk that firing in the wrong direction could silhouette the firing ship.) A ship's commanding officer usually reserves authority of ordering the guns to fire (since he bears responsibility for any damage inflicted on friendly forces), but the gunnery officer was sometimes delegated (or assumed at his own peril) limited authority in combat situations. Firing illuminating shell normally required authorization by the escort commander because it revealed the convoy location for much greater distances than it provided useful illumination.
The white light of starshells would damage night vision -- although not as much as you might expect because of the distance and potential for filtering through low clounds. It was often fired at times when night vision had already suffered from nearby explosions, fires, distress flares, and non-flashless gunpowder. Certain personnel might be designated to protect their vision from star shell exposure. =AL=</HTML>
| Subject | Written By | Posted |
|---|---|---|
Starshell
|
Nathan Greenfield | 12/11/2001 11:24PM |
|
Re: Starshell
|
AL Wellman | 12/16/2001 01:41AM |