The Curtiss A-3 was a ground attack aircraft produced for the US Army Air Corps by modifying the existing O-1 Falcon observation aircraft. The O-1 was a two-seat single engined biplane, constructed with a frame of aluminium tubing connected by steel tie-rods. The wings were wooden framed and fabric covered. The wings were staggered, with the longer upper wing placed forward of the shorter lower wing. To improve pilot visibility the centre of the upper wing was located well forward, with the ends swept back at nine degrees.
The standard O-1B carried two fixed forward firing guns synchronised to fire through the propeller arc and two flexible guns in the rear cockpit. Two more fixed forward firing guns were added to the A-3, located in the lower wing just outboard of the propeller arc to allow them to fire at high speed. The A-3 was also given bomb racks under the lower wings. The A-3 was powered by the Curtiss V-1150-3 (D-12D) engine, and had similar performance figures to the O-1B.
The prototype A-3 was produced by modifying a standard O-1B (no. 27-243). This aircraft was later converted back to the O-1B standard. Three orders for a total of 66 A-3s followed. Six of these aircraft were later disarmed, given dual controls, and used as training aircraft with the designation A-3A.
In 1928 the AAC carried out a series of aerial operations at Army service schools in place of the normal manoeuvres. The first A-3s arrived in time to take part in these exercises, with nine of them forming an attack squadron alongside sixteen O-2s.
A further 78 A-3s were ordered in 1930. These aircraft included all of the improvements made to the Falcon between the O-1B and the O1-E, and were designated the A-3B. These changes included the use of Frise ailerons, horn-balanced elevators and oleo-pneumatic shock absorbers. By 1931 seventy of the A-3Bs made up the bulk of attack aircraft used in that year’s manoeuvres, with the rest being made up of a small number of A-3s.
The Air Corps was not really happy with the A-3. Acceptable aircraft were designated as “standard” – i.e. the standard bomber or standard fighter of the Air Corps, but the A-3 was labelled as either “limited” or “substitute” standard. The last of the A-3Bs was scrapped in October 1937.
A-3B (Curtiss Model 44)
Engine: Curtiss D-12E (V-1150)
Span: 38ft 0in
Length: 27ft 7in
Height: 10ft 3in
Empty Weight: 2,902lb
Gross Weight: 4,476lb
Maximum Speed: 139.4mph
Cruising Speed: 111mph
Climb rate: 948ft/ second
Range: 647 miles with 100 gallons of fuel
Guns: Four fixed and two flexible machine guns
Bomb load : 200lb
Curtiss Aircraft, 1907-1947, Peter M Bowers (Amazon.co.uk)
Curtiss Aircraft, 1907-1947, Peter M Bowers (Amazon.com)