1936 Waco ZPF-6

Restoring the Rare 1936 Waco ZPF-6

The 1936 Waco ZPF-6, now undergoing restoration as part of The Caldwell Collection at Mustang Field, is one of the rarest Waco biplanes ever built. Only five F6 models were produced between 1935 and 1937, making this restoration a significant aviation milestone.The ZPF-6 represents the transition between Waco’s earlier sport biplanes and the later military trainers.

​

This aircraft, serial number 4378, was originally delivered to the Department of Revenue for the Commonwealth of Pennsylvania and painted in Alexander blue with Vesta yellow funnel striping and red accents—matching the colors of the Pennsylvania state flag. Custom-ordered, it featured:

✔️ Jacobs L-5 engine (285 HP), making it the fastest of the Waco F-series
✔️ Single Seat in the front cockpit. – commonly outfitted for 2
✔️ Electrically heated pitot tube (a rarity for the time)
✔️ Extra fuel tanks, extending total capacity to 73.5 gallons
✔️ Full instrumentation in both cockpits, including a rare two-way radio provision and heat.

​

After its initial government use, NC16579 passed through multiple owners, serving as:
✈️ A secondary trainer for the Civilian Pilot Training Program (WWII-era)
✈️ A crop duster in Iowa after the war
✈️ A workhorse for multiple flying services across Pennsylvania, Massachusetts, and Minnesota

Declared scrapped in 1949, the aircraft's remains were rediscovered in 1984, then passed through several hands before being purchased in 2024 for restoration.

​

With so few examples of the ZPF-6 ever made—and even fewer surviving—this aircraft represents a rare opportunity to restore a truly historic Waco model. While similar models, such as the UPF-7, can be modified to resemble an F6, there is no substitute for an authentic restoration.

​

Restoring NC16579 will involve:
✔️ Rebuilding it to original Waco specifications using TCDS #586
✔️ Preserving its unique design elements, including the smooth cowl and wider landing gear
✔️ Returning it to the air for the first time in 78 years

The Waco ZPF-6 is an aviation rarity. With only one other F6 still intact, this restoration ensures that an authentic example of the F6 series will return to the skies!