Bowlus/Nelson BB-1 Dragonfly (motor glider)

https://en.wikipedia.org/wiki/Nelson_Dragonfly

The Bowlus/Nelson BB-1 Dragonfly is an American, two seat, strut-braced,
high-wing motor glider that was developed from the Bowlus BA-100 Baby Albatross
glider by Hawley Bowlus.

The development of the Dragonfly was sponsored by the Nelson Engine Company to
promote the use of their H-44 25 hp (19 kW) four cylinder two-stroke engine. The
engine was mounted in the rear of the fuselage pod, in pusher configuration,
with the wooden two bladed 42 in (107 cm) propeller below the metal tail boom.
The fuel tank holds 3 U.S. gallons (11 L; 2.5 imp gal), enough for
self-launching, but not for cross-country powered flight.

The Dragonfly shares the Baby Albatross's molded plywood fuselage pod, aluminium
tube tail boom and strut-braced double spar wooden wing, covered in aircraft
fabric aft of the spar. The leading edge is a plywood D-cell. The aircraft
features dual controls and a retractable tricycle landing gear with a steerable
nose wheel. The engine is started by a ratchet-wire recoil start system that
allows restarts in flight, as well as on the ground.

Federal Aviation Administration certification of the type was achieved on 21
April 1947, with Nelson Aircraft Corporation as the certificate holder and the
type officially known as Nelson Auxiliary Power Glider BB-1. The type
certificate indicates that neither the engine nor the propeller need be
certified. The type certificate specifies that the Nelson H-49 engine of 28 hp
(21 kW) may also be installed.

The Dragonfly was later replaced in production by the improved Nelson
Hummingbird PG-185B.


Role
Motor glider

National origin
United States

Manufacturer
Hawley Bowlus

Designer
Hawley Bowlus

Introduction
1947

Number built
7

Developed from
Bowlus BA-100 Baby Albatross

In operational use the Nelson powerplant proved heavy and lacking in power and,
as the Sailplane Directory terms it, "the result was an under-powered
sailplane". The 25 hp (19 kW) engine gave the Dragonfly a sea level climb rate
of just 235 fpm (1.19 m/s) and a take-off run of 900 ft (274 m). As a result of
the performance deficiencies only seven were produced.

In March 2011 there were still four BB-1s registered in the US, two of which had
been transferred to the National Soaring Museum.

Specifications (Dragonfly)

General characteristics
Crew: one
Capacity: one passenger
Wingspan: 47 ft 4 in (14.43 m)
Wing area: 169 sq ft (15.7 m2)
Aspect ratio: 13.25
Empty weight: 580 lb (263 kg)
Gross weight: 940 lb (426 kg)
Fuel capacity: 3 U.S. gallons (11 L; 2.5 imp gal)
Powerplant: 1 × Nelson H-44 four cylinder, two stroke, 25 hp (19 kW)
Propellers: 2-bladed wooden, 3 ft 6 in (1.07 m) diameter

Performance
Maximum glide ratio: 18:1
Rate of climb: 235 ft/min (1.19 m/s)
Wing loading: 5.56 lb/sq ft (27.1 kg/m2)



*