Fall 2024 Piper L-4H Grasshopper Update

Between 1941 and 1945, the USAAF procured  5,413 L-4s for U.S. forces. 1,801 of that number were L-4H versions. Thousands of L-4s remained in the US for the duration of WWII, training pilots and serving liaison duties for Army units in training. The little Piper L-bird is common in the United States and Canada, but combat veteran L-4s are rare in the United States.

L-Birds accompanied the advance of the troops until the war ended. While many of the fighters and bombers were repatriated to the United States post war, most small planes were decommissioned on the spot. These aircraft were then used after the war for training thousands of pilots in the former European and Pacific theaters.

The past weeks have seen the L-4’s wings rebuilt, the wheels and brake parts inspected and restored, and the fuselage tube frame has been repaired and returned to the AirCorps restoration shop.

The original brake system expander  (left) and brake drum (right). The bladder expands against the brake shoes and produces friction as the shoes are pressed against the brake drum. 

An  L-4B and L-4H are nearly identical. A primary difference between them is the brake system manufacturer.  L-4Bs used Goodrich brakes and L-4Hs used a Scott system. The original expander tube brake system in an L-4 is quite simple. Pressure on the wheel brake lever pushes on a diaphragm which in turn forces brake fluid in the line to inflate the expander tube which pushes the brake pads against the brake drum.

The original L-4/J-3 brakes aren’t very effective. However, this can be an advantage in a Cub because in typical operations the J-3/L-4 needs almost no brake use. With expander tube brakes it’s hard to brake it hard enough to pick up the tail.

More effective replacement brake systems are powerful enough to make a brake-induced nose over a real possibility. But current L-4/J-3 Cub owners are not inexperienced cadets so they often choose to accept the nose-over risk and retrofit their airplanes with Grove disc brakes under an FAA-approved Supplemental Type Certificate and that’s the case with 44-79780’.