US Navy Aircraft Grey on metal parts 1931-?

[Toryu]

Hi,

Does anybody know when exactly the requirement to paint all metal and wooden parts of the fuselage etc. in Navy Aircraft Grey (Spec SR-15a) was discontinued and changed back to all-silver?  Perhaps with SR-15b in 1936 or later.  Which new airplanes were affected by the change, i.e. not painted grey anymore?

No opinions, please.  I would ask for a fact-based expert statement.

Thanks

[Dana Bell]

Hi Toryu,

 

The whole gray/aluminum issue bounced around Navy offices for most of the 1920s and ‘30s.  Here’s a short rundown, though there were many exceptions to what follows.  First, it’s important to remember that nearly all Navy aircraft finish coats were enamels - pigments added to spar varnish.  There were experiments with pigmented dopes and lacquers, and the Navy was aware that the Army was having good results, but most specifications and contracts called for enamel finish coats.

 

During WWI the basic overall color could be French Gray or Naval Gray.  By 11 Jun 1919 the Bureau of Aeronautics ordered that fabric surfaces be finished in aluminum paint, noting the improved preservative values of the metallic pigment.  In June 1924 Tech Order 68 stipulated aluminum enamel on metal, wood, and fabric, but by the following January the fleet was complaining that aluminum-painted hulls and floats were difficult to keep clean.  In May 1925 TO 101 revised the Navy’s scheme, calling for aluminum enamel on metal and fabric, with hulls and floats in naval gray.  (Most hulls and floats of that time were still wooden.)

 

In October 1926 the BuAer allowed that Aluminum alloy floats could have one finish coat of Navy Gray or aluminum enamel.  Continued difficulties with the adherence of aluminum enamel on the Navy’s metal primers led to SR-15a in August 1931: all exterior metal or wood was to be finished in gray, with fabric in aluminized enamel.

 

Tests of new aluminum finishes continued through the ‘30s, and on 2 May 1935 BuAer announced that the overall aluminum scheme would soon be standardized (starting with the PBY-1).  Aluminum lacquers were authorized, but BuAer expected continuing reports on their effectiveness.  This was formalized in SR-15b on 15 Aug 1936.  

 

The change took some time to catch up with older aircraft.  Battle Force wanted the aluminum finish to begin at overhaul stations after 20 April 1937, while NAS Norfolk complained that a lack of supplies would prevent them from applying aluminum enamels before June 1937.

 

Somewhere in all of this, the Navy finally learned the joys of aluminized dope.  This meant that most aircraft continued to display differences between metal finishes and wood/fabric finishes – it was not possible to match finishes when mixing aluminum pigments with dopes and lacquers.

 

As for any particular model you’re considering, photos will always give you the best indication whether to apply aluminum, gray, or both.

 

Cheers,

 

Dana