HGU-2/P
The HGU-2/P and APH-5 were based on the same helmet with the USAF standardizing theirs as the HGU-2/P, the US Navy and US Army had the APH-5 and APH-5A respectively. Just like the US Navy the USAF considered more than one design for replacing the trusty P-helmet series that had served the USAAF and USAF well from 1948 onwards. General Textile Mills appears to have offered a version designated DH-5, very much like the DH-5-3 offered to the US Navy, but in the end the USAF chose the same basic MSA design as the US Navy.

An example of the General Textile Mills (Gentex) DH-5 helmet which appears to have been tested by the US Air Force as a possible successor to the P-series helmets. Very little is known about its development except for the fact that Gentex applied for patent for the visor in August 1955 and the patent went through in November 1957. A US Navy version, the DH-5-3, was tested by that service too but none of the helmets were adopted for service use.

The Navy began their development around 1956 and the USAF assigned the HGU-2/P nomenclature to their version on 15 August 1957 and it was produced in accordance with the military specification MIL-H-26671 dated ???. The HGU-2/P helmet seems to have been fielded from 1959 and differed from the US Navy APH-5 in a few areas. The communications and the oxygen mask tabs are different and so is the colour of the neoprene edgeroll. Identifying features of the HGU-2/P helmet are a heavy helmet shell, often with a poorly painted finish (applies especially to helmets manufactured by Consolidated Components Corp.), thick grey or tan neoprene edgeroll, visor housing with metal strip reinforcement along the visor lock knob track, metal visor tracks, and a three-piece styrene energy absorbing liner. The HGU-2/P is equipped with an H-149/AIC headset identifiable by the MX-2088/U earcups, the double nylon string attachment and the microphone plug hanging loosely from the side of the helmet. Original HGU-2/P helmets came with leather oxygen mask attachment tabs in tan leather with three snaps on each (early USN APH-5 helmets had black tabs with only two snaps on each). Later HGU-2/P helmets were often field modified with Hardman receivers for christmas tree bayonets or cast aluminium receivers for single bayonets. Some were also modified with the three ventilation holes in the crown, often seen as an identifying hallmark of early HGU-2A/P helmet.

HGU-2/P in early configuration with leather oxygen mask tabs and push buttor visor lock knob. Note the metal visor tracks and the metal strips along the visor lock button track. This helmet was manufactured by Consolidated Controls
Corporation in December 1960. The oxygen mask communications configuration is not correct. It should have had an early CX-4707/AIC Y-cord ending in a U-93A/U plug at the hose end. This particular helmet was acquired by the Royal Danish Air Force for test purposes which is why it does not have the usual USAF decal on the visor housing.
Pictures © Bluelight

H-149/AIC headset as used in HGU-2/P helmets. It consists of H-143/AIC receivers, MX-2088/U earpads, attachment
rings and a communication cord. The headset is fixed to the helmet shell with nylon strings at the top and bottom of
the metal attachment ring. The nylon strings are visible on the outside of the helmet shell. Note the hanging micro-phone plug in the picture far right. The headset is adjusted to the user by putting a number of foam rubber pads between the earphones and the helmet shell. Pictures © Bluelight

HGU-2/P modified with Hardman receivers and christmas tree bayonets. As can be seen from the pattern of holes in the second picture from the left this helmet has had cast aluminium oxygen mask receivers at an earlier stage. Pictures © Milehigh

HGU-2/P modified with cast aluminium oxygen mask receivers. HGU-2/P helmets were seen both with this white type of receivers and the black self-adjusting cast receivers. The black visor lock knob is not original but a later retrofit. Pictures © kd6hlr

HGU-2/P Strategic Air Command
Apparently the Strategic Air Command (SAC) intended to use the HGU-2/P helmet without visor as a successor to the MB-4 helmet. The helmets were produced without the standard holes for the visor housing and three snaps were added to the brow area to allow the fitting of a bill like the one used on the HGU-9/P. This is documented by period photographs and a few surviving helmets but more detailed information has so far to be discovered.

HGU-2/P modified for use in Strategic Air Command. It has the same three snaps over the face opening as other SAC
helmets from the same general period like the HGU-9/P This helmet is not complete. It is missing fitting pads and communications. Pictures © Figmo

HGU-2A/P (early version) 1961-1966
The HGU-2A/P was issued around 1961 as an improved version of the HGU-2/P. The HGU-2A/P nomenclature (USAF way of indicating an upgrade to the HGU-2/P is with the "A") was assigned 2 Nov 1960 as the result of design changes documented by both SAC (Form 81 16 Nov 1959) and TAC (Form 81 28 Oct 1959). The first HGU-2A/P military specification MIL-H-26671A was issued 16 March 1961 allowing production to begin. Just like its US Navy ancestor, the APH-5, the HGU-2/P was too heavy and suffered from heat build-up problems. The HGU-2A/P contains improved fitting pads that make the helmet more stable and an adjustable nape strap. The shell has three ventilation holes in the crown under the visor housing. The early and middle HGU-2A/Ps are the only models that came with such holes from the factory but it is a T.O. approved modification used both on HGU-2/P helmets and on later HGU-2A/P and HGU-26/P helmets based on the HGU-22/P shell. The helmet shell is reduced in weight when compared with the HGU-2/P and has an improved finish, especially when compared with HGU-2/P helmets made by Consolidated Controls. The early HGU-2A/P introduced a new type of headset, the H-154/AIC. It is easily identifiable with its spring-loaded metal mounting arms. The visor housing had air louvres at the rear edge to allow the windblast to escape more easily during an ejection. The reinforcing strips along the visor lock knob track were changed from metal to plastic.

Early HGU-2A/P made by Sierra Engineering Co. in November 1962. Note the blue plastic strips along the visor lock knob track and the visor cover with louvres at the rear edge. Pictures © Bluelight

Far left: The six-lobe lock knob made exclusively by Sierra Engineering Co. Middle left: The microphone plug is not fixed with an S-hook as seen on later helmets. This was specific to Sierra helmets. The S-hook was used on Gentex helmets. Middle right: Early HGU-2A/P helmets have three factory-made ventilation holes in the helmet shell under the visor housing. Far right: The H-154/AIC headset is mounted on spring-loaded metal arms that are fixed to the helmets shell using the same screws that hold the headset drawstring studs on the outside of the helmet. Pictures © Bluelight

HGU-2A/P (middle version) 1966-1969
The HGU-2A/P military specification was updated to become MIL-H-26671B on 1 December 1966. The specification is not too specific (no pun intended) on what changes were made from the original 1961 spec but photo evidence shows that at least the visor housing was changed. The old glassfibre housing was replaced by a new lighter plastic housing with integral reinforcing ridges along the visor lock knob track. The lock knob itself was standardised to become a white four-lobe knob with a square cross section. This helmet version was produced by at least three companies, Gentex, Sierra Engineering Corp., and Land Mfg. Co.

The HGU-2A/P (middle version) can be identified by its plastic visor housing with the square four-lobe visor lock knob, the original HGU-2A/P helmet shell with the three cooling holes, and the H-154/AIC headset with its spring-loaded metal arms. The best way to identify it is, however, the label with its reference to MIL-H-26671B. The picture to the far right shows a label with a spelling error (22671B vice 26671B). The pictures show four different helmets. All pictures are © unknown.  

HGU-2A/P with ramshorn double visors
Both Sierra and Gentex introduced double visor assemblies for the HGU-2A/P helmets in the 1960s. Due to their construction they are colloqually known as ramshorns visors, a term that was actually coined by the inventor of the concept, Sierra Engineering (see the ad below). Sierra's visor housing was made in one piece while Gentex' housing consisted of a separate centre visor cover and two visor housing extensions for the visor lock knobs and actuating rods. Consequently the two visor types are referred to as one-piece and three-piece ramshorns visors respectively. The two visor types were never adopted as military standard by USAF and therefore did not get any military designation or stock numbers. They were. however, used in quite large numbers by USAF aircrew. Modifying an HGU-2A/P helmet with a ramshorn visor did not change the helmet's designation either. It was still an HGU-2A/P. The visors were, however, mentioned in the USAF Technical Orders as being commercially available.

Three pictures to the left: HGU-2A/P helmet with Gentex' three-piece ramshorn visor. © Cretanman. Middle right: Ad for Sierra's one-piece ramshorns visor. Right and far right: HGU-2A/P helmet with Sierra's one-piece ramshorns visor. © Cretanman and Bluelight

HGU-22/P
The HGU-22/P is not a helmet, it is a helmet shell. HGU-22/P "Helmet shell, Flying" type designation was assigned 26 April 68 and the military specification MIL-H-83147 was issued 24 June 1968. The first Qualified Production List (QPL-83147) was issued 19 March 1969 identifying Gentex and Sierra as the only two manufacturers at that time. According to the MIL-H-83147 the HGU-22/P consists of a helmet shell, an polystyrene energy absorbing liner, front edge pad (brow pad), edge beading, chin strap and nape strap. It was not intended as a helmet in its own right. It was to be employed as the basic unit to which other essential components and accessory items (e.g. visor and communications) could be installed by the users to obtain the required final helmet configuration.

This is what you would get if you ordered an HGU-22/P helmet shell from Gentex. No visor, no communications and no oxygen mask retention hardware. One thing is missing from this particular HGU-22/P - the brow pad which is supposed to sit above the face opening and hold the styrene liner in position. © Bluelight

HGU-2A/P (late version) 1969-1974?
After the introduction of the HGU-22/P helmet shell the HGU-2A/P nomenclature was used to signify a helmet based on the HGU-22/P shell fitted with a single visor and an H-154A/AIC headset. There is no military specification covering this configuration; reference is just made to the HGU-22/P specs. It is unclear when the HGU-2A/P designation disappeared but it may have been already in 1974. MIL-H-26671B was cancelled in 1974 without a superceding document and Gentex sold single visor HGU-26/P helmets already from that year.

A late version HGU-2A/P ordered in 1973. This particular helmet is not the most beautiful I have ever seen. It was stored for at least 30 years in a basement without ever being issued as evidenced by the missing oxygen mask receivers. The foam in earphones and fitting pads is heavily deteriorated. © Bluelight

HGU-26/P double visor
The HGU-26/P request for nomenclature is dated Jan 14, 1970 and is based on the HGU-22/P Helmet Shell. There is no military specification detailing exactly what goes into an HGU-26/P but until the appearance of the single visor HGU-26/P both USAF and manufacturer information was consistent in describing the HGU-26/P as an HGU-22/P helmet shell with a PRU-36/P side-actuated double visor.

HGU-26/P with PRU-36/P double visor assembly, thin edge beading and fitting pads. This is the standard configu-ration that usually comes to mind when people talk about HGU-26/P helmets. © Bluelight

HGU-26/P single visor
There are strong indications that both Sierra and Gentex sold single visor HGU-26/P helmets from late 1974. Gentex' 1974 catalogue has no HGU-2A/P but shows single visor and double visor versions of the HGU-26/P, and Sierra delivered single visor HGU-26/P helmets in January 1975 based on a 1974-dated order as witnessed by the pictures below. Single visor helmets based on the HGU-22/P shell and manufactured after late 1974 are therefore single visor HGU-26/P helmets, not HGU-2A/P. 

Single visor HGU-26/P manufactured by Sierra according to a DSA order placed in 1974. Together with other evidence it strongly suggests that the HGU-2A/P designation disappeared around that time. © kd6hlr.

Quarter Helmet Assembly
In the late 1970s it had become commonplace to use custom fit liners. Most customers had no use for the styrene energy absorbing liner. As a consequence Gentex and Scott started to field the so-called Quarter Helmet Assembly. It is comprised of a bare HGU-22/P helmet shell with chin and nape straps and either single or dual visor assembly completely installed. The customers would then install liners, oxygen mask receivers and communications to suit their needs. The earliest order I have observed for a Quarter Helmet Assembly was placed in 1978.

This is not an HGU-26/P helmet even if eBay sellers and second hand dealers would like us to think so. It could, however, become one. The pictures show a quarter helmet assembly fresh out of the manufacturer's cardboard box. It is just an empty helmet shell with chin and nape straps and a PRU-36/P double visor housing. This will only become an HGU-26/P helmet if a liner and an H-154A/AIC headset are added. © Bluelight.

Custom fit helmets and other 'anomalies'
The HGU-2/P, HGU-2A/P and HGU-26/P helmets have been modified and upgraded to meet every user's whims over the years. The most common modifications are custom fit liners instead of the standard fitting pads and the single visor cover gullwing cut to improve the pilot's upward visibility. Both these features are included in the helmet prepared by Protection Inc. for the USAF Thunderbirds display team. A modification that is less known is the cut-back of the PRU-36/P visor cover to provide the same improvement in upward visibility as the gullwing cut on the single visor housing.

HGU-2A/P custom fit and painted by Protection Inc for the USAF aerobatic team Thunderbirds. As can be seen from Protection Inc.'s label on the right this helmet IS an HGU-2A/P and NOT an HGU-33/P as claimed by so many over the years. HGU-33/P is a US Navy helmet and the USAF's finest just do not use Navy helmets. Pictures © maty

Far left and left: A standard single visor housing and a visor housing modified with the so-called gullwing cut. The gullwing profile appears because the central visor lock knob track does not allow a straight cut across the face opening. Pictures © kd6hlr and unknown. Right and far right: A standard PRU-36/P visor housing and a visor housing cut back to allow improved upwards visibility. This modification is also authorised. Pictures © Bluelight