HPK SP-1
# HPK SP-1

The HPK SP-1 a.k.a. "Some Pisser-1" is a single seat homebuilt aircraft.

## Design and development

Engle Flying Service members, Harold Hayden, Art Payne, Robert Kinney, and Norman R. Benner developed the HPK SP-1 over the course of five years. Plans for a two-seat side by side, and four seat variants were not completed.

The SP-1 is a single-place, all-metal, low-wing aircraft with conventional landing gear and partial span split trailing edge flaps. The cowling is from a Piper Tri-Pacer.

## Operational history

The aircraft was built and tested at Three-M airfield in Pennsylvania, home of Kaiser-Fleetwings Company. The prototype has been registered for over 50 years.

## Specifications (HPK SP-1)

Data from sport aviation

General characteristics

* Length: 19 ft 1 in (5.82 m)
* Wingspan: 25 ft (7.6 m)
* Height: 8 ft 1 in (2.46 m)
* Wing area: 99 sq ft (9.2 $m^2)$
* Airfoil: 4412
* Empty weight: 1,300 lb (590 kg)
* Powerplant: 1 × Lycoming O-235-C1 , 115 hp (86 kW)
* Propellers: 2-bladed

Performance

* Maximum speed: 140 kn (160 mph, 260 km/h)
* Cruise speed: 126 kn (145 mph, 233 km/h)
* Stall speed: 43 kn (50 mph, 80 km/h)
* Wing loading: 13 lb/sq ft (63 $kg/m^2)$
