Helmet and Visor Blast Performance - Page 52

Helmet and Visor Blast Performance

Helmet/Visor Blast pic

Objective
Evaluate the capability of a wide range of different visor and helmet systems to protect a deminer from the effects of a blast AP landmine.

Description
In this study, three types of lightweight protective helmets were evaluated: the Sport Helmet developed by Med-Engwith visors of nominal thickness values of 4.5 mm (0.173 in.), 5.0 mm (0.196 in.), and 5.7 mm (0.224 in.); a construction hardhat mounted with a full face visor of 4.3 mm (0.17 in.) thickness designed and constructed by Hameed and Ali Research Center; and a 4.8 mm (0.19 in.) nominal thickness full face visor mounted on a headband, manufactured by Lightweight Body Armor, Ltd. The hardhat and headband systems were used in conjunction with the Med-EngHumanitarian Demining Ensemble (HDE), but with the chest plate removed in order to simulate a standard flak vest or ballistic apron. The full HDE with the chest plate installed was used during most of the tests with the Sport Helmet. Simulated mines, consisting of C4 plastic explosives, were buried with 1 cm of overburden. Three sizes of simulated mines were used containing 50, 100 and 200 grams of C4, chosen to represent a wide range of blast type AP landmines.

	Contractor/Developer U.S. Army CECOM Night Vision and Electronic Sensors Directorate 10221 Burbeck Road, Ste 430 Fort Belvoir, VA 22060-5806 ATTN: Charles W. Chichester Phone: (703) 704-1055 Fax: (703) 704-3001 Email:charles.chichester@nvl.army.mil

Performance

In all tests, regardless of charge size, the visor was blown off both the hardhat and headband systems. When the Sport Helmet was used with the integrated chest plate, the visor was removed in just over 25% of the tests (out of 19 tests); and in 60% of the trials (out of 14 tests) without the interfacing chestplate. One benefit of having a visor remain in place over the face throughout the mine detonation sequence was demonstrated by observing the intense short-lived fireball which could easily engulf a deminer's upper body including the face. The presence of a visor ensures that burn injuries are kept to a minimum. Also, the overpressure at the ear was shown to be positively affected by a head protection system - the Sport Helmet consistently permitted lower peak overpressure levels from reaching the ear as compared to the hardhat and headband systems. Tests with a range of visor thicknesses demonstrated that even a small increase in thickness has a significant effect on the ability of the visor to prevent high velocity fragmentation from reaching the face of a deminer. For example, the test results demonstrated that by increasing visor thickness from 5.0 to 5.7 mm, one could decrease the chance of a fragment penetration of the visor by a factor of 8.

Status

The results of the study are available on the DoD Humanitarian Demining website at humanitariandemining.org.

Med-Eng Systems Sport
Helmet with a full face visor.

Hameed & Ali Research helmet
Hameed and Ali
Research Center hardhat
with a full face visor.

Leightweight Body Armor helmet
Lightweight Body Armor
Ltd. full face visor
mounted on an
adjustable headband.

Humanitarian Demining Developmental Technologies 2000 - 2001