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Letord LET (Series)

Three-Seat, Twin-Engine Biplane Reconnaissance Bomber Aircraft

France | 1916

"Only about 300 Letord series three-seat biplanes were realized out of the 1,500 ordered by the French Aeronautique Militaire during World War 1."

Authored By: Staff Writer | Last Edited: 04/04/2017 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site; No A.I. was used in the generation of this content.
Beginning in 1909, Emile-Louis Letord began construction of aircraft out of a facility in Meudon near Paris, France. Ultimately the company was commissioned to build aircraft from other manufacturers (including Dorand and Nieuport) until the concern headed development of their own three-seat biplane - the Letord Let.1. The series encompassed the Let.1 up to the Let.7 and some 1,500 were eventually ordered by the French Air Force for service in World War 1 (1914-1918) but only about 300 were realized.

World War 1 puched many new military technologies and one of these was large, multi-engined aircraft types to serve in the long-range reconnaissance, bombing, and escort roles. For a time, airships handled these over-battlefield roles with limited success but advancements made in air-to-air interception and ground-based Anti-Aircraft Artillery (AAA) limited the tactical value had in these slow-moving, gas-filled systems.

In 1916, the Letord "Let", in prototype form, recorded its first flight and this three-man, twin-engined platform was developed along the lines extended-range reconnaissance. To cover the distances required of the type, a multi-engine arrangement was used and this fitted to a relatively large airframe. The aircraft relied on a traditional biplane wing arrangement for lift and control and the crew required to man its various systems numbered three. "Negative wing stagger" was present in the over-under wing arrangement where the lower planes were set well-forward of the upper sections, making the parallel struts angle rearwards. Power was from 2 x engines of various makes and models throughout the service life of the aircraft and each was charged with driving two-bladed propellers. The engines were held outboard of the fuselage and atop the lower wing assembly. Each of the three crewmen sat in separate open-air cockpits so communication between them was limited. The undercarriage showcased double-wheeled main legs and a tail skid though a nose leg was usually added to prevent "nose-over" accidents when ground-running (common to larger aircraft of the war). The tail unit was marked by a single vertical fin and low-mounted horizontal planes.

Design of this aircraft was attributed to Emile Dorand.

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Standard armament was defensive in nature and involved a pair of dedicated machine gunners. The forward-most cockpit was given 2 x machine guns atop a trainable mounting and a further 1 or 2 x machine guns were installed near amidships (dorsally). For offensive-minded, light-to-medium bombing sorties the aircraft could be equipped with up to 660lb of conventional drop stores.

Performance-wise, the aircraft could reach speeds of 90-to-100 miles-per-hour out to ranges of 220 miles and an altitude of 16,000 feet.

The initial form offered was the Let.1 which carried 2 x Hispano-Suiza 8A engines and this was followed by the similar Let.2 model with Hispano-Suiza 8Ba engines. The Let.3 was introduced as more of a dedicated bomber form (to include the Bn3 night bomber) and relied on the same engines as the Let.2 variant. The Let.4 was a reconnaissance platform carrying 2 x Lorraine-Dietrich 8A series engines while the bomber variant, Let.5, was similar to this but carried the Lorraine-Dietrich 8Fb engine of 240 horsepower (each) instead.

Let.6 emerged as a large escort fighter and was given the official designation of "Ca.3" in French service. These were notable in their carrying of a 37mm cannon in the nose and being powered by 2 x Hispano-Suiza 8Be 8-cylinder water-cooled engines of 220 horsepower (each). The Let.6 was born from the Let.3 Bn3 night bomber but the type was more or less made obsolete by technological advancements had in the war.

The final notable mark became Let.7 which was another bomber development. This product reverted to the Lorraine-Dietrich powerplants.

The Let series bombers were not exported and quickly fell to history with the end of the war in November 1918.

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Power & Performance
Those special qualities that separate one aircraft design from another. Performance specifications presented assume optimal operating conditions for the Letord Let.5 Three-Seat, Twin-Engine Biplane Reconnaissance Bomber Aircraft.
2 x Lorraine-Dietrich 8Fb engines of 240 horsepower each and driving two-bladed propeller units.
96 mph
155 kph | 84 kts
Max Speed
15,978 ft
4,870 m | 3 miles
Service Ceiling
217 miles
350 km | 189 nm
Operational Range
City-to-City Ranges
Operational range when compared to distances between major cities (in KM).
The nose-to-tail, wingtip-to-wingtip physical qualities of the Letord Let.5 Three-Seat, Twin-Engine Biplane Reconnaissance Bomber Aircraft.
36.3 ft
11.05 m
O/A Length
59.2 ft
(18.05 m)
O/A Width
12.1 ft
(3.70 m)
O/A Height
3,660 lb
(1,660 kg)
Empty Weight
5,401 lb
(2,450 kg)
Design Balance
The three qualities reflected below are altitude, speed, and range. The more full the box, the more balanced the design.
Available supported armament and special-mission equipment featured in the design of the Letord LET (Series) Three-Seat, Twin-Engine Biplane Reconnaissance Bomber Aircraft .
1 OR 2 x Machine guns on trainable mounting in nose cockpit position.
1 OR 2 x Machine guns on trainable mounting in dorsal midships position.

Up to 660lb of conventional drop munitions.
Notable series variants as part of the Letord LET (Series) family line.
LET - Base Series Designation
Let.1 - Original production model; dedicated reconnaissance model; fitted with Hispano-Suiza 8A series engines.
Let.2 - Based on Let.1 but with Hispano-Suiza 8Ba engines.
Let.3 - Dedicated bomber form; Hispano-Suiza 8Ba engines.
Let.4 - Dedicated reconnaissance model; fitted with Lorraine-Dietrich 8A engines.
Let.5 - Dedciated bomber form; Lorraine-Dietrich 8Fb engines.
Let.6 (Ca.3) - Escort fighter variant; 1 x 37mm cannon in nose cockpit; 1 x Machine gun amidships; Hispano-Suiza 8Be engines.
Let.7 - Dedicated bomber variant; Lorraine-Dietrich engines fitted.
Global customers who have evaluated and/or operated the Letord LET (Series). Nations are displayed by flag, each linked to their respective national aircraft listing.

Total Production: 300 Units

Contractor(s): Letord - France
National flag of France

[ France ]
Relative Max Speed
Hi: 100mph
Lo: 50mph
Aircraft Max Listed Speed (96mph).

Graph Average of 75 MPH.
Era Crossover
Pie graph section
Showcasing Aircraft Era Crossover (if any)
Max Alt Visualization
Small airplane graphic
Production Comparison
Entry compared against Ilyushin IL-2 (military) and Cessna 172 (civilian) total production.
MACH Regime (Sonic)
RANGES (MPH) Subsonic: <614mph | Transonic: 614-921 | Supersonic: 921-3836 | Hypersonic: 3836-7673 | Hi-Hypersonic: 7673-19180 | Reentry: >19030
Aviation Timeline
1 / 1
Image of the Letord LET (Series)
Image from the Public Domain.

Mission Roles
Some designs are single-minded in their approach while others offer a more versatile solution to airborne requirements.
Some designs stand the test of time while others are doomed to never advance beyond the drawing board; let history be their judge.
Going Further...
The Letord LET (Series) Three-Seat, Twin-Engine Biplane Reconnaissance Bomber Aircraft appears in the following collections:
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