Another easy one.
It's a Lockheed Y1C-23.
The Lockheed Y1C-23 ‘Altair’ was the designation given to the sole DL-2 Altair after it was purchased by the USAAC.
The 'Altair' was an improved version of the Lockheed 8 Sirius, originally produced at the request of Charles Lindbergh. The basic Sirius was a low wing monoplane with a wooden fuselage and a fixed undercarriage. At the same time Lindbergh requested the production of a modified wing with a retractable undercarriage that could be swapped for the fixed undercarriage version. In the end Lindburgh never used the alternative wing, and so Lockheed installed it on a Sirius to produce the first Altair.
This second aircraft was produced by converting an existing Lockheed DL-2 'Sirius' (NR8494). The DL-2 was produced after Lockheed had been taken over by the Detroit Aircraft Company, with DL-2 standing for 'Detroit Lockheed Model 2' (the DL-1 was an improved version of the Lockheed Vega). The DL-2 had a metal fuselage and wooden wing, and tandem enclosed cockpits. It was originally used as a company demonstrator between August 1930 and April 1931.
In the spring of 1931 the aircraft was given a new retractable undercarriage and a 500hp Pratt & Whitney SR-1340E engine. Later in 1931 the aircraft was purchased by the Army Air Corps. It went to Wright Field for service testing, and then moved to Bolling Field, where it was used as a staff transport. It was used by the Assistant Secretary of War (Frederick Huff Payne until 1933 and then Harry Hines Woodring), the Chief of the Air Corps and other senior officers, and logged 1,075 flying hours. During this period it made at least five wheels-up landings, but survived intact. It eventually became a ground instructional airframe at Chanute Field, Illinois, before being scrapped at the Middletown Air Depot in Pennsylvania in June 1942.
Engines: Pratt & Whitney SR-1340E
Power: 500hp
Crew: 1
Wing span: 42ft 9in
Length: 28ft 4in
Height: 9ft 6in
Empty weight: 3,235lb
Gross weight: 4,896lb
Cruising speed: 175mph
Payload: 1,290lb/ 1 or 2 passengers