OP 1664 U.S: Explosive Ordnance (Vol. 1); Chapter 9 - Ground Pyrotechnics; Section 2 - Flares: High-Altitude Parachute Mortar-Fired Flare Mk 20 Mod 0

U.S. EXPLOSIVE ORDNANCE

PART 3 - PYROTECHNICS

Chapter 9 - GROUND PYROTECHNICS

Section 2 - FLARES

High-Altitude Parachute Mortar-Fired Flare Mk 20 Mod 0

Length, inches	10.75
Diameter, inches	2.5
Weight, pounds	5
Height of trajectory, feet	1,000
Intensity, candlepower	85,000
Color	White
Burning time, seconds	60
Rate of fall after ignition, ft./sec.	16

Use: This high-altitude flare is used to illuminate seaplane landing areas at night, and to illuminate an island base when low ceilings do not permit proper visibility from normal flying levels.

Flare: The flare consists of a cylinder steel tube body with a copper cup welded to the closed end of the tube. The body contains an expelling charge, a pyrotechnic cand-le, and a silk parachute. The copper cup contains a fuse assembly, a propelling charge, 25 grams of a combination smokeless powder and black powder, and a standard shotgun primer.

Mortar: The mortar consists of a steel tube 36 inches long and 2.8 inches in diame-ter. The tube is screwed into a steel base plate 0.75 inch thick and 12 inches square. The base plate is provided with a central stud into which is pressed a hardened steel fir-ing pin.

Operation: Remove the closing cap from the end of the mortar. Attach a 30-foot lan-yard to the brass release pin and insert the pin the two holes drilled transversly about six inches from the end of the mortar. Insert the flare into the mortar so that it rests on the release pin, with the copper end down. Fire the flare by pulling the lanyard, thus remov-ing the release pin. The flare falls to the bottom of the mortar, firing the primer. The pri-mer sets off the propelling charge and ignites the delay fuse. The expanding gases for-ces the copper cup away from the flare and fill the bore of the mortar. The flare is pro-pelled 1,000 feet into the air, at which time the delay fuse ignites the expelling charge. The pyrotechnic candle and parachute are expelled, the expelling charge igniting the candle.

Remarks: A suitable barrier should be erected to shield personnel firing the flare. In case of a misfire, wait at least three minutes before disassembling the mortar. Clean mortar tube after firing.