British SAP-I Hispano

[nathanieljr]

Hello all, just wondering about the mechanics of the 20mm SAP-I round.
Was the filler weight/volume the same as the HE rounds? Did the side walls, of mild steel, crush on impact to release the SR 365? Was the heat from this what acted as the ignition? And roughly how much armour could it penetrate?
Many thanks for your replies

 

[kahu1]

They contain a detonator under the AP tip.
I understand the shell was essentially the same as the HEI shell.
It is Semi AP, as the tip is the AP part,so fairly light.

Bob

 

[lcn]

hello
I recommend the book "British 20mm Hispano by P.Labbett & PJF Mead" (Technical ammunition guide)
He will answer your questions
J-Paul

 

[Tony Williams]

To add a little more detail, three SAPI variants were listed by Labbett: Mark 1.z, Mark 2.z and Mark 3.z. All used the same shell body as the HE and all had a hardened steel nose cap screwed into the body instead of a fuze.

The Mark 1.z had four equal increments of SR 379 incendiary mix, each weighing about 3 grammes; so a total of 12 grammes incendiary out of the total weight of 134 grammes (slightly heavier than the HE and HEI at 129-130 g). The incendiary was ignited solely by the shock of impact. The expansion of the burning gas generated by ignition presumably burst the shell body and/or blew off the nose cone and the steel base plate.

The Mark 2.z and Mark 3.z both replaced the top incendiary element with a detonator; this contained 0.4 g of CY detonator in the Mark 2, 0.4 g of ZY detonator in the Mark 3.

All three types were expected to penetrate 20mm plate at normal impact (perpendicular) at 200 metres and ignite petrol in cans placed behind the plate.

All had the same colour scheme: a red shell body and a white nose cap.

The typical mid/late war belt sequence used by the RAF was two HEI followed by two SAPI.

 

[nathanieljr]

Thats great, thank you all!