The Australian War Memorial Collection. Test site
Near Mareeba, Qld. 15 March 1944. Graceful curves of the CAC Boomerang fighter aircraft. This example is RAAF serial No. A46-126, coded "BF-S" and with nose art featuring a left facing figure with boxing gloves and the word "SINBAD II". This aircraft flew with No.5 (Tactical Reconnaissance aka 'TR') Squadron RAAF, piloted by 402769 Flight Lieutenant A W B Clare of Newcastle, NSW. Note the muzzle cover over the distinctive 20mm Hispano cannon barrel which protrudes from the leading edge of the wing.
These covers were fitted to keep tropical condensation droplets out of the metal barrels whilst in flight. The condensation could freeze in the below zero degrees conditions potentially forming an ice plug in the cannon barrel. In some cases where this did occur in flight the first 20mm shell fired could be prematurely detonated causing serious damage to the aircraft.
In order to prevent this a doped material cover could be applied over the exposed muzzle. The first shot fired would puncture a hole through the thin protective cover from which following rounds could safely follow.
Hispano Mk5* Aircraft Cannon, marked HISPANO 20mm GUN BIRKIGT PATENTS BRITISH M.A.R.C. LTD. and the serial number. It has a yellow painted number 6 on the left side. This aircraft Hispano Cannon was
An RAAF training film on the 20mm Hispano Cannon of the type mounted on the Supermarine Spitfire. The film covers the examination of the external parts, the barrel assembly, stripping the cannon, remo
Kiriwina, Trobriand Islands, Papua. September 1943. Two US servicemen show interest in No. 79 Squadron RAAF armourers servicing an Hispano 20mm cannon from the Squadron's Spitfire Mk Vc A58-137, UP-T
Kiriwina, Trobriand Islands, Papua. September 1943. No. 79 Squadron RAAF airmen working on the starboard side 20mm Hispano cannon in the mainplane of one of the Squadron's Spitfire Mk Vc aircraft, on
Kiriwina, Trobriand Islands, Papua. December 1943. 37383 Leading Aircraftman C. A. (Clyde) Woodbridge, a Fitter Armourer of No. 79 Squadron RAAF working on the Hispano 20mm cannon of the Supermarine S
Goodenough Island, D'Entrecasteaux Group, Papua. 26 June 1943. 402719 Flying Officer A. H. (Peter) Birch, GD Pilot, sitting on the 20mm Hispano cannon of a No. 79 Squadron RAAF Spitfire Mk Vc aircraft
