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Letord LET (Series)

France (1916)
Picture of Letord LET (Series) Three-Seat, Twin-Engine Biplane Reconnaissance Bomber Aircraft

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.


Detailing the development and operational history of the Letord LET (Series) Three-Seat, Twin-Engine Biplane Reconnaissance Bomber Aircraft.  Entry last updated on 4/4/2017. Authored by Staff Writer. Content ©www.MilitaryFactory.com

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.
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.






Our Data Modules allow for quick visual reference when comparing a single entry against contemporary designs. Areas covered include general ratings, speed assessments, and relative ranges based on distances between major cities.

Image of collection of graph types

Relative Maximum Speed Rating
Hi: 100mph
Lo: 50mph
    This entry's maximum listed speed (96mph).

    Graph average of 75 miles-per-hour.
Relative Operational Ranges
NYC
 
  LON
LON
 
  PAR
PAR
 
  BER
BER
 
  MOS
MOS
 
  TOK
TOK
 
  SYD
SYD
 
  LAX
LAX
 
  NYC
Graph showcases the Letord Let.5's operational range (on internal fuel) when compared to distances between major cities.
Aviation Era Impact
Pie graph section
Pie graph section
Pie graph section
Pie graph section
Pie graph section
Useful in showcasing the era cross-over of particular aircraft/aerospace designs.
Unit Production Comparison
Comm. Market HI*: 44,000 units
Military Market HI**: 36,183 units
300
300


  * Commercial Market High belongs to Cessna 172.

  ** Military Market High belongs to Ilyushin Il-2.


Altitude Visualization
Small airplane graphic
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Supported Mission Types:
Air-to-Air
Interception
Unmanned
Ground Attack
Close-Air Support
Training
Anti-Submarine
Anti-Ship
Airborne Early Warning
MEDEVAC
Electronic Warfare
Maritime/Navy
Aerial Tanker
Utility/Transport
Passenger Industry
VIP Travel
Business Travel
Search/Rescue
Recon/Scouting
Special Forces
X-Plane/Development
National Flag Graphic
National Origin: France
Service Year: 1916
Classification Type: Three-Seat, Twin-Engine Biplane Reconnaissance Bomber Aircraft
Manufacturer(s): Letord - France
Production Units: 300
Global Operators:
France
Structural - Crew, Dimensions, and Weights:
Unless otherwise noted the presented statistics below pertain to the Letord Let.5 model. Common measurements, and their respective conversions, are shown when possible.

Operational
CREW


Personnel
3


Dimension
LENGTH


Feet
36.25 ft


Meters
11.05 m


Dimension
WIDTH


Feet
59.22 ft


Meters
18.05 m


Dimension
HEIGHT


Feet
12.14 ft


Meters
3.7 m


Weight
EMPTY


Pounds
3,660 lb


Kilograms
1,660 kg


Weight
LOADED


Pounds
5,401 lb


Kilograms
2,450 kg

Installed Power - Standard Day Performance:
2 x Lorraine-Dietrich 8Fb engines of 240 horsepower each and driving two-bladed propeller units.

Performance
SPEED


Miles-per-Hour
96 mph


Kilometers-per-Hour
155 kph


Knots
84 kts


Performance
RANGE


Miles
217 mi


Kilometers
350 km


Nautical Miles
189 nm


Performance
CEILING


Feet
15,978 ft


Meters
4,870 m


Miles
3.03 mi

Armament - Hardpoints (4):

STANDARD (Let.5):
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.

OPTIONAL:
Up to 660lb of conventional drop munitions.
Visual Armory:

Graphical image of an aircraft conventional drop bomb munition
Variants: Series Model Variants
• 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.