Keystone LB-6

The Keystone LB-6 and LB-7 were 1920s American light bombers, built by the Keystone Aircraft company for the United States Army Air Corps, called Panther by the company, but adoption of the name was rejected by the U.S. Army.

KeystoneLB7oak (4477474236)
Keystone LB-7
Role Biplane light bomber
Manufacturer Keystone Aircraft
First flight 1927
Introduction 1929
Retired 1934
Primary user United States Army Air Corps
Number built 17 production LB-6
18 production LB-7

Design & development

The LB-6 was in competition with the Curtiss XB-2 for production in early 1928 and although the Curtiss aircraft was clearly the better of the two, the conservative Army Air Corps leadership chose the Wright-powered LB-6 and the Pratt & Whitney-powered LB-7, ordering 35 aircraft.

The LB-6/LB-7 was the first operational service model of a 13,000 lb (5,897 kg) twin-tail biplane bomber of a series produced by Keystone. 35 served operationally between 1929 and 1934. A number of variants were built for test and evaluation purposes but never placed into production or service. The LB-10 variant became the basis for the B-3 to B-6 series of similar bombers that were the last biplane bombers ordered by the Air Corps.

The Keystone XLB-6 prototype was created by refitting the final triple-tailed Keystone LB-5 (serial number 27-344) with an LB-5A tail unit; longer (75 foot) straight-chord, untapered and noticeably swept-back wings; and 525 hp (391 kW) Wright Cyclone R-1750-1 radial engines suspended on struts between the wings rather than mounted on the lower wing. This produced a bomber with twice the rate of climb as the LB-5 and slightly faster cruise speed. Production LB-6s featured a five-foot longer fuselage.

The LB-7 used the same extended-span LB-6 airframe powered by Pratt & Whitney Hornet engines.

The remaining variants were ordered before the 1930 change of designators by the United States Army Air Corps from "LB-" (Light bomber) to "B-", but were delivered after the change. Although delivered as bombers, they saw service as cargo and observation aircraft. The LB-10 variant became the basis of the B-3 through B-6 bombers, all of which used the original LB-6 design, and which served as the primary bombardment force of the Army Air Corps prior to the advent of the monoplane bomber.

Operational history

Keystone XLB-12
XLB-12 prototype
Keystone XLB-12 side view
XLB-12 port-side view

According to an article in the Baltimore Sun the XLB-12 Prototype was used on a refueling and bombing trial in April 1929.[1] Big Bomber to be Refueled during Flight "The huge twin-motored army bomber (sic) which will take off from Dayton, O., fly to New York City and be refueled while in midair, after which she will drop bomb flares on the city and make a return flight to the Dayton army field. The flight is to be a practicable demonstration by the Army Air Corp of the value of refueling airplanes in the air when engaged in bombing expeditions over a long distance". The aircraft was wrecked in August the same year.[2]

Eight LB-6s and all operational LB-7s were delivered to the 20th and 96th Bomb Squadrons of the 2nd Bomb Group at Langley Field, Virginia, and the 11th Bomb Squadron of the 7th Bomb Group at Rockwell Field, California, between January and September 1929. The nine remaining LB-6s were sent to the 23rd and 72nd Bomb Squadrons, attached to 5th Composite Group at Luke Field, Hawaii, between July and September 1929. In May 1930 three LB-6s were re-engined to become LB-7s and transferred to the 25th Bomb Squadron of the 6th Composite Group based at France Field in the Panama Canal Zone, where they were all written off in 1931.

Beginning in March 1931 the surviving bombers in the Continental United States were taken out of front-line service, re-designated the ZLB-6 and ZLB-7, and sent to the 40th School Squadron at Kelly Field, Texas, where all were scrapped or surveyed by April 1935. The Hawaiian LB-6s served until 1934, when they too were surveyed in-situ.


One LB-5 modified for evaluation.
Production version with Wright R-1750-1 Cyclone radial engines of 525 hp (391 kW), 17 built in 1929.
LB-6 with 525 hp (391 kW) Pratt & Whitney R-1690 Hornet A engines, 18 built in 1929 and three LB-6s re-engined as LB-7s in 1930.
One LB-7 re-engined with 550 hp (410 kW) Pratt & Whitney R-1860 Hornet B engines for evaluation.
One LB-7 re-engined with 575 hp (429 kW) Wright GR-1750B geared engines for evaluation.
One LB-6 re-engined with 525 hp (391 kW) R-1690-3 Hornet A engines.
Production version of the XLB-10, 63 built, all redesignated B-3A prior to delivery. 36 built as B-3A with Pratt & Whitney engines; the remaining 27 became B-5s with Wright engines.
One LB-6 re-engined with 525 hp (391 kW) R-1750-3s for evaluation.
LB-11 re-engined with 525 hp (391 kW) GR-1750s for evaluation.
Similar to the LB-7, with 575 hp (429 kW) R-1860-1 Hornet B engines for evaluation.
Proposed version with 525 hp (391 kW) GR-1690 Hornet A engines; seven ordered, but re-engined and re-designated before production. Five delivered as the Y1B-4, two as the Y1B-6.
Proposed version with 575 hp (429 kW) GR-1860 Hornet B engines; three ordered, but re-engined and re-designated before production. Delivered as the Y1B-5.
1931 designation of two LB-6 and the LB-11 (in 1933) as training aircraft.
1931 designation of ten LB-7 as training aircraft.


 United States

Specifications (LB-6)

Keystone Panther 3-view Aero Digest July 1928
Keystone Panther 3-view drawing from Aero Digest July 1928

Data from Keystone LB-6, National Museum of the USAF fact page

General characteristics

  • Crew: Five
  • Length: 49 ft 03 in (15.01 m)
  • Wingspan: 75 ft 0 in (23.0 m)
  • Height: 18 ft 1 in (5.5 m)
  • Wing area: 1,148 ft2 (106.38 m2)
  • Empty weight: 7,024 lb (3,186 kg)
  • Gross weight: 13,440 lb (6,100 kg)
  • Powerplant: 2 × Wright Cyclone R-1750-1 radial engine, 525 hp (391 kW) each


  • Maximum speed: 114 mph (183 km/h)
  • Cruise speed: 95 mph (153 km/h)
  • Range: 632 miles (1,017 km)
  • Service ceiling: 11,650 ft (3,550 m)
  • Rate of climb: 600 ft/min (180 m/s) 


  • 2 × trainable .303 in (7.7 mm) Lewis guns in open position in nose
  • 2 × trainable .303 in (7.7 mm) Lewis guns in open dorsal position
  • 1 × trainable .303 in (7.7 mm) Lewis gun in ventral hatch
  • 2,000 lb (910 kg) Bombs

See also

Related development

Related lists


  1. ^ 1929 note attached to original 1929 AP photo from Baltimore Sun archive
  2. ^
  • John Andrade. U.S.Military Aircraft Designations and Serials since 1909, p. 135. Midland Counties Publications, 1979. ISBN 0-904597-22-9.
  • The Illustrated Encyclopedia of Aircraft (Part Work 1982–1985), p. 2255. Orbis Publishing, 1985.
  • Keystone LB-6, NMUSAF article
  • Keystone LB-7, NMUSAF article
  • Keystone LB-8, NMUSAF article
  • Keystone LB-9, NUMUSAF article
  • Keystone LB-10, NMUSAF article
  • Keystone LB-13, NMUSAF article
  • Keystone LB-14, NMUSAF article
  • "Looking Down on Uncle Sam's Latest Bomber" Popular Mechanics, August 1930
20th Bomb Squadron

Not to be confused with XX Bomber CommandThe 20th Bomb Squadron is a unit of the 2d Operations Group of the United States Air Force located at Barksdale Air Force Base, Louisiana. The 20th is equipped with the Boeing B-52H Stratofortress.

Formed in May 1917 as the 20th Aero Squadron, the squadron saw combat in France on the World War I Western Front. It took part in the St. Mihiel offensive and Meuse-Argonne offensive.

After the war, it served with the Army Air Service and Army Air Corps as the 20th Bombardment Squadron During the 1920s and 1930s, the squadron was involved in field service testing of new bomber aircraft, notably the Y1B-17 Flying Fortress.

During World War II the squadron fought in the North African and Italian Campaigns. It was awarded a Distinguished Unit Citation for its actions during a raid on Steyr, Austria.

It was a part of Strategic Air Command during the Cold War. As a medium bomber squadron it deployed to stand alert at forward bases in "Reflex" operations. After equipping with Boeing B-52 Stratofortresses stood nuclear alert, but during the Viet Nam War the squadron deployed frequently to perform Operation Arc Light bombing missions. Since 1993, the 20th Bomb Squadron has flown the B-52H Stratofortress long-range strategic bomber, which can perform a variety of missions. Today the squadron is engaged in the Global War on Terrorism.

23rd Bomb Squadron

The 23rd Bomb Squadron is a United States Air Force unit, assigned to the 5th Bomb Wing. It is stationed at Minot Air Force Base, North Dakota. The mission of the squadron is to fly the Boeing B-52H Stratofortress strategic bomber. The squadron stands ready to deploy and fly its B-52Hs to enforce national security policy by being ready to deliver overwhelming nuclear or conventional firepower to destroy targets, worldwide, at any time.

The squadron is one of the oldest in the United States Air Force, dating to 16 June 1917, when it was organized at Kelly Field, Texas. It deployed to England as part of the American Expeditionary Forces, being engaged as an aircraft repair squadron during World War I. The squadron saw combat during World War II, and became part of the Strategic Air Command (SAC) during the Cold War.

25th Space Range Squadron

The 25th Space Range Squadron is a non-flying squadron of the United States Air Force. It is assigned to the Nevada Test and Training Range at Schriever Air Force Base, Colorado. The 25th operates the Space Test and Training Range along with the reserve 379th Space Range Squadron.

The 25th is one of the oldest units in the United States Air Force, its earliest predecessor in the days of the USAAS being organized as the 20th Aero Squadron on 13 June 1917 at Camp Kelly, Texas, and almost immediately redesignated, due to a clerical error, as the 25th Aero Squadron by 22 June. The squadron deployed to France and fought on the Western Front during World War I as a pursuit squadron within the week before the Armistice. The unit was demobilized after the war in 1919.The squadron's second predecessor was organized as the 25th Squadron (Bombardment) in 1921 as part of the permanent United States Army Air Service, the squadron served in the Panama Canal Zone during the Inter-War period, then as part of Twentieth Air Force in the Pacific Theater of Operations of World War II flying Boeing B-29 Superfortress bombers. During the Cold War, it was part of Strategic Air Command, equipped with Boeing B-47 Stratojet medium bombers until its inactivation in 1964.

Keystone Aircraft

Keystone Aircraft Corporation was an early pioneer in airplane manufacturing. Headquartered in Bristol, Pennsylvania, it was formed as Ogdensburg Aeroway Corp in 1920 by Thomas Huff and Elliot Daland, but its name was quickly changed to Huff-Daland Aero Corp, then to the Huff-Daland Aero Company. The company made a name for itself in agricultural aircraft, and then in the United States Army Air Corps' early bomber aircraft. From 1924, James McDonnell was the chief designer.

In 1926, Huff left the company, and it was soon purchased by Hayden, Stone & Co., who increased capital to $1 million (United States) and renamed it Keystone. In 1928, it merged with Loening and was known as Keystone-Loening. In 1929, it was taken over by Curtiss-Wright. Also in 1929, the Keystone- Loening plant on the East River in New York City was closed by Curtis- Wright and the operation was moved to the Bristol, Pa. Keystone plant. A small band of the top Loening management, design and shop workers (all New Yorkers) did not want to go to Bristol. They instead started their own aircraft company in a small rented shop in Baldwin, NY in Jan. 1930. The principal players were Leroy R. Grumman, Leon "Jake" Swirbul and William Schwendler. Grumman Aircraft went on to stellar heights with some of the top Naval aircraft in Navy history. Grumman also designed and built the Lunar Excursion Module (LEM) that landed US astronauts on the moon. Keystone itself became a manufacturing division of Curtiss-Wright and ceased production in 1932.Lieut. Comdr. Noel Davis and Lieut. Stanton H. Wooster were killed in their Keystone Pathfinder American Legion while conducting a test flight, just days before they were to attempt a trans-Atlantic flight for the Orteig Prize.

Keystone B-3

The Keystone B-3A was a bomber aircraft developed for the United States Army Air Corps by Keystone Aircraft in the late 1920s.

List of Interwar military aircraft

Interwar military aircraft are military aircraft that were developed and used between World War I and World War II, also known as the Golden Age of Aviation.

For the purposes of this list this is defined as aircraft that entered service into any country's military after the armistice on 11 November 1918 and before the Invasion of Poland on 1 September 1939.

Aircraft are listed alphabetically by their country of origin. Civilian aircraft modified for military use are included but those that remained primarily civilian aircraft are not.

List of aircraft (K)

This is a list of aircraft in alphabetical order by manufacturer beginning with K.

List of military aircraft of the United States

This list of military aircraft of the United States includes prototype, pre-production, and operational types. For aircraft in service, see the list of active United States military aircraft. Prototypes are normally prefixed with "X" and are often unnamed (note that these are not the same as the experimental X-planes, which are not generally expected to go into production), while pre-production models are usually prefixed with "Y".

The United States military employs a designation and naming system to provide identifications to all aircraft types. Until 1962, the United States Army, United States Air Force (formerly Army Air Force), and United States Navy all maintained separate systems. In September 1962, these were unified into a single system heavily reflecting the Air Force method. For more complete information on the workings of this system, refer to United States Department of Defense Aerospace Vehicle Designations.

This list does not include aircraft used by the U.S. military services prior to the establishment of a numerical designation system. For these aircraft, see List of military aircraft of the United States (1909–1919). It also does not include aircraft designated under the pre-1962 United States Navy designation system. For these aircraft, see List of military aircraft of the United States (naval).

United States Army Air Corps

The United States Army Air Corps (USAAC) was the aerial warfare service component of the United States Army between 1926 and 1941. After World War I, as early aviation became an increasingly important part of modern warfare, a philosophical rift developed between more traditional ground-based army personnel and those who felt that aircraft were being underutilized and that air operations were being stifled for political reasons unrelated to their effectiveness. The USAAC was renamed from the earlier United States Army Air Service on 2 July 1926, and was part of the larger United States Army. The Air Corps became the United States Army Air Forces (USAAF) on 20 June 1941, giving it greater autonomy from the Army's middle-level command structure. During World War II, although not an administrative echelon, the Air Corps (AC) remained as one of the combat arms of the Army until 1947, when it was legally abolished by legislation establishing the Department of the Air Force.The Air Corps was renamed by the United States Congress largely as a compromise between the advocates of a separate air arm and those of the traditionalist Army high command who viewed the aviation arm as an auxiliary branch to support the ground forces. Although its members worked to promote the concept of air power and an autonomous air force in the years between the world wars, its primary purpose by Army policy remained support of ground forces rather than independent operations.

On 1 March 1935, still struggling with the issue of a separate air arm, the Army activated the General Headquarters Air Force for centralized control of aviation combat units within the continental United States, separate from but coordinate with the Air Corps. The separation of the Air Corps from control of its combat units caused problems of unity of command that became more acute as the Air Corps enlarged in preparation for World War II. This was resolved by the creation of the Army Air Forces (AAF), making both organizations subordinate to the new higher echelon.

On June 20, 1941, the Army Air Corps' existence as the primary air arm of the U.S. Army changed to that of solely being the training and logistics elements of the then-new United States Army Air Forces, which embraced the formerly-named General Headquarters Air Force under the new Air Force Combat Command organization for front-line combat operations; this new element, along with the Air Corps, comprised the USAAF.The Air Corps ceased to have an administrative structure after 9 March 1942, but as "the permanent statutory organization of the air arm, and the principal component of the Army Air Forces," the overwhelming majority of personnel assigned to the AAF were members of the Air Corps.

Manufacturer designations
Patrol aircraft
Observation aircraft
Scout aircraft
USAAS/USAAC/USAAF/USAF bomber designations, Army/Air Force and Tri-Service systems
Original sequences
Main sequence
Long-range Bomber
Tri-Service sequence


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