I will fill in the rest of the Alexander "Eaglerock" model history.
The long wing biplane was so-called because the LOWER wing was 38 feet long with upper wing 36 feet long. A bit odd-looking. There was also a combi-wing or combination wing Eaglerock with Curtiss OX-5 with 36 foot upper wing and 32 foot lower wing-this was ATC-7, also issued 27 April 1927. Then came the A-1 biplane with just 8 inch longer wings than the comb-wing still with the OX-5 OR with the 220 Hp Wright J-5 air-cooled engine, ATC-57 issued August 1928. The A-2 also had A-1 wings with the OX-5 but a longer fuselage and lighter weight, ATC-58 also issued August 1928. The A-3 and A-4 were similar but Hisso-powered, either 150 or 180 Hp Hissos. These were American versions of the French wartime Hispano-Suiza, first made by Wright-Martin and later known as the Wright A and Wright E. The A-3 and A-4 differed from the A-2 by having a nose radiator.
The A-5 also used a war-surplus engine-the rare Menasco-Salmson of 260 Hp but converted in America from water-cooled radial to air-cooled radial. The A-5 never got an ATC, the few built flying unlicensed, only registered as was then permitted.
The A-7 was only a single aircraft built with Category 2 as 2-1 issued 1 January 1929. It used an imported German Siemens air-cooled radial of 125 Hp known in America as the Ryan-Siemens. Next Alexander Eaglerock was the A-11 using the Warner Scarab air-cooled radial of only 110 Hp not very successfully and no record of ATC or category 2 approval. The A-12 used the little-known 130 Hp Comet radial, but ATC-139 was issued May, 1929. This sold for $5,847. The A-13 used a unique Curtiss Challenger, a six cylinder two-row radial of 170 Hp; ATC-141 issued May 1929.
That brings us to Rob's A-14 submission which used the 165 Hp Wright J-6-5 (a basic Wright J-6 with 5 cylinders, OR Wright J-6-7s and J-6-9s) not certificated but licensed in Category 2, certificate 2-103 issued July 31, 1929. Finally the Alexander A-15 biplane similar to the A-14 except using a Kinner K-5 of 100 Hp from five radial cylinders (that produces an exceptional sound I can verify!) The A-15 ATC was No. 190 issued July 1929 with original price of $4,157 but lowered to $3,907 later.
The prolific series of biplanes from Alexander tried other various engines, but none others were issued any ATCs. Alexander was only one of a plethora of aircraft manufacturers stimulated by Charles Lindbergh's record non-stop New York to Paris solo flight of May 20-21, 1927 in 33.5 hours in a high wing Ryan NYP one-off monoplane with Wright J-5 Whirlwind radial of 220 Hp.