A number of the Keystone aircraft became one off flying testbeds for various newly developed geared or direct drive versions of the Hornet and Cyclone engines. This programme gave rise to the new designations LB 8, LB 9, LB 10, LB 11, LB 11A and LB-12. Most of these were conversions from existing LB 6 or LB 7 bombers.
Inter-Wars
Keystone LB-10 / B-3 / B-5
A number of the Keystone aircraft became one off flying testbeds for various newly developed geared or direct drive versions of the Hornet and Cyclone engines. This pro¬gramme gave rise to the new designations LB 8, LB 9, LB 10, LB 11, LB 11A and LB¬-12. Most of these were conversions from existing LB 6 or LB 7 bombers.
The major production model which follow¬ed was the single tailed LB 10A, powered originally by 525 hp R 1690 3 Hornets, of which 63 were built. These were delivered under the new designation B 3A, the USAAC having adopted a single ‘B’ category for all types of bomber in 1930. Later, 27 of them were refitted with R 1750 3 Cyclones in place of the Hornets and were redesignated B 5A.
LB 10A
Engine: 525 hp R 1690 3 Hornet
Span: 22.78 m (74 ft 9 in)
Length: 14.88 m (48 ft 10 in)
Gross weight: 5875 kg (12 952 1 b)
Maximum speed: 183 km/h (114 mph).
Keystone LB-9
A number of the Keystone aircraft became one off flying testbeds for various newly developed geared or direct drive versions of the Hornet and Cyclone engines. This programme gave rise to the new designations LB 8, LB 9, LB 10, LB 11, LB 11A and LB-12. Most of these were conversions from existing LB 6 or LB 7 bombers.
Keystone LB-8
A number of the Keystone aircraft became one off flying testbeds for various newly developed geared or direct drive versions of the Hornet and Cyclone engines. This programme gave rise to the new designations LB 8, LB 9, LB 10, LB 11, LB 11A and LB-12. Most of these were conversions from existing LB 6 or LB 7 bombers.
Keystone LB-6 / LB-7
The Keystone LB series had been characterized by tapered wings, but the XLB 6 of 1927 (converted from the tenth LB 5) introduced constant chord wings with new powerplant (two 525 hp Wright R 1750 1 Cyclone radials) mounted between the wings, and a lengthened fuselage. Thus modified, this became the standard configuration for the remaining Keystone LB types, beginning with 17 production LB 6s and continuing with 18 LB 7s, which were identical except for their 525 hp Pratt & Whitney R 1690 3 Hornet engines.
Keystone LB-1 / LB-3
The XLB-1 three-seat, single-engine light bomber was tested in 1923.
The single engined configuration, mounting an 800 hp Packard, proved unsuitable and the basic LB 1 airframe was redesigned by Keystone in 1927 as the twin engined XLB-3A, with two 410 hp Pratt & Whitney R 1340-1 Wasp nine cylinder radials mounted midway between the equal span wings. The complement was increased from three to five (pilot, copilot, bombardier, and front and rear gunners) and the bombardier was located more conventionally in the nose, instead of amidships as in the LB 1.
In 1924 Huff-Daland was reorganized as Keystone Aircraft Corporation and the production bomber aircraft was known by this latter company name.
Keystone XB-1 / Huff‑Daland XB‑1
Huff Daland’s XB 1 bomber design of 1926 was cancelled and reordered as the Keystone XB 1B, a five seat biplane with two 600 hp Curtiss V 1570 5 Conqueror engines. It never progressed beyond prototype stage.
Keystone Aircraft Corp
Originally Huff-Daland; became Keystone March 1927, still centered at Bristol, Pennsylvania.
The XLB-1 three-seat, single-engine light bomber was tested in 1923 and was developed as the twin-engined XLB-3, with a crew of five. In 1924 Huff-Daland was reorganized as Keystone Aircraft Corporation and the production bomber aircraft was known by this latter company name.
Keystone was main supplier of twin-engined bombers to U.S. Army from 1927 to 1932, when James McDonnell (later of the McDonnell Douglas Company) was chief engineer. LB- 5A (25 delivered in 1928) was first true Keystone bomber. Largest USAAC bomber order in a decade was for 63 LB- 10A (all converted to B-3A and B-5A on change of Army categories).
Last production contracts for bombers placed 1931 (for 25 B-4A and 39 B-6A).
Keystone Aircraft Corporation built a total of 220 aircraft in the US Army Air Corps LB (light bombardment) category, venturing briefly also into the B (bombardment) and HB (heavy bombardment) classifications. All except ten of the LBs were twin engined aircraft, but had their origins in the single-engined XLB 1 prototype and nine pre series LB 1 biplanes produced in 1925 by Keystone’s predecessor company, Huff Daland and Co Inc of Ogdensburg, New York, which became Keystone in March 1927.
Pathfinder was three-engined civil transport; NK a biplane trainer for a 1928 competition (19 built); PK a twin-engined flying-boat based on NAF design (18 delivered in 1931). Patrician was three-engined 20-passenger low-wing monoplane.
Later absorbed Loening, becoming Keystone-Loening, and then became part of Curtiss-Wright.
Other types were characteristically Loening, including the OL-8 biplane amphibian; the Air Yacht civil amphibian; and the Commuter four-seat cabin amphibian.
Kermer Vienna
Soaring plane, Austria, 1923
Kentucky Cardinal
Kentucky Aircraft Corp was founded in 1926 to manufacture a three-seat biplane named the Kentucky Cardinal. The two aircraft completed were of welded steel tube construction and powered by Curtiss OX-5 engines.
All Aero 