The L-4 “Grasshopper” was the military version of the popular Piper J-3 Cub first introduced in 1938. Essentially the same aircraft, windows were added to the aft cabin of the J-3 to improve visibility, and the typically yellow Cub was painted olive drab. The L-4 was originally designated the O-59 when in 1942 the Secretary of War ordered the designation Observation changed to Liaison.
The U.S. Army Air Forces (AAF) ordered the first O-59s in 1941 for tests in conjunction with the military’s growing interest in the use of light aircraft for liaison and observation duties in direct support of ground forces. The L-4 was the first aircraft mass produced for this use. Between 1941 and 1945, the AAF procured 6,066 copies of the militarized J-3 and variants, of which 5,453 were L-4 models and 100 were AE-1 Air Ambulance versions of the J-5.
During WWII, “Grasshoppers” performed a wide variety of functions throughout the world such as for artillery fire direction, pilot training, medical evacuation, courier service, and front-line liaison. Members of the Civil Air Patrol flew thousands of hours in light planes such as the L-4 searching for enemy submarines in U.S. coastal waters. Piper was based in Lock Haven, Pennsylvania.
Wingspan: 35 ft 3 in
Length: 22 ft 5 in
Height: 6 ft 8 in
Empty weight: 640-765 lb
Useful load: 455 lb
Max. takeoff weight: 1,200–1,220 lb
Wing area: 178.5 sf
Engine: 65 hp Continental O-170-3 (military designation), Continental A-65-8
Crew: 2 (pilot and observer/passenger)
Max. speed: 85–87 mph
Cruise speed: 75 mph
Range: 190–260 miles
Takeoff distance (over 50-foot obstacle): 730 ft
Landing distance (over 50-foot obstacle): 470 ft
Rate of climb: 450 fpm
Service ceiling: 9,300–11,500 ft
Wing loading: 6.84 lb/sf
Note: The L-4F and L-4G, built in 1951, were based on the 3-seat Piper J-5. While the J-5 had previously been used for the AE-1/HE-1 Air Ambulance, the L-4F and L-4G were not ambulance versions.