HGU-35/P helmet

The HGU-35/P helmet was developed in the late 1970s in order to meet US Navy requirements for a new lighter fixed wing helmet. Experience from the Vietnam conflict had shown that the APH-6 helmet and A-13A oxygen mask combination was not satisfactory any more. It had excessive weight and bulk, poor fit and discomfort, it impaired vision, in was unstable under high "g", and it had a misplaced centre of gravity. The HGU-33/P and HGU-34/P helmets and MBU-14/P oxygen mask had been developed as a short-term solution to the problem. They were lighter than the APH-6/A-13A combination but they did not solve other problems like the misplaced centre of gravity.
The HGU-35/P was developed as an integrated helmet oxygen/communications system. The integral oxygen subsystem featured a new lightweight low-profile mask (Carleton mask), an integral oxygen duct through the helmet, and an external hose with communications wires connecting to the helmet at the rear. This configuration was meant to enhance aircrew performance under high "g" loading due to the reduction in mask weight and elimination of the front "elephant trunk" oxygen hose.
The HGU-35/P Operational Test and Evaluation was carried out in Spring 1979 as the final phase in test and evaluation before a production decision. Apparently the helmet did not meet expectations and the helmet was never put into production.

HGU-35/P in early configuration with a standard EEK-4/P visor housing. Note the oxygen hose is pointing downwards
from its exit at the rear of the helmet. In four of the pictures the so-called Carleton oxygen mask is visible. It was
developed especially for the HGU-35/P. Pictures © Gentex Corporation

HGU-35/P in later configuration with a new visor housing with an off-center visor lock knob. Note the oxygen hose
is pointing to the left. Pictures © Paul Taylor