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Pterodactyl Pfledgling / Acro-Dactyl

 

pfledge
Pfledgling 430D


Fledgling, a name which rapidly became abbreviated to Fledge. In 1978, Jack McCormack adapted this wing for powered flight and formed the Pterodactyl company to sell the aircraft thus modified. Wanting to link the product unmistakably with his company, he added a silent 'P' to the model name, and the Pfledgling was born.
The Pfledge, as this aircraft is usually known, is the basic model from which all the Pterodactyl range is derived, apart from the Light Flyer.

Single-seat single-engined high-wing monoplane with hybrid control. Wing has swept back leading and trailing edges, and tapering chord; no tail. Pitch control by weight-shift; yaw control by tip rudders; no separate roll control; control inputs through weight-shift for pitch and stick for yaw. Wing braced from above by kingpost and cables, from below by cables; wing profile Klaus Hill; double-surface. Undercarriage has three wheels in tricycle formation; bungee suspension on nosewheel and glass-fibre suspension on main wheels. No ground steering. No brakes. Aluminium-tube framework, without pod. Engine mounted below wing driving pusher propeller.

This aircraft owes its existence to Klaus Hill, who was tragically killed on 10 October 1978 while testing the Voyager, a hang-glider of his own design which he had just motorised.

Klaus had earlier designed a rigid tip-rudder hang-glider with hybrid control called the Fledgling, a name which rapidly became abbreviated to Fledge. In 1978, Jack McCor-nack adapted this wing for powered flight and formed the Pterodactyl company to sell the aircraft thus modified. Wanting to link the product unmistakably with his company, he added a silent 'P' to the model name, and the Pfledgling was born.

The Pfledge, as this aircraft is usually known, is the basic model from which all the Pterodactyl range is derived, apart from the Light Flyer. In February 1979, Jack McCornack and Dan White made a flight of 50 mile (80 km) in a straight line between Watsonville and Morgan Hill to get to the Great Barnstorming Airshow. One of the first ultralight cross-countries, this was acknowledged as a veritable exploit and the Pfledge received the best-new-design award and several glowing reports in the specialised press.

That August, Jack, with Keith Nicely, completed in 71 flying hours the trip from Watsonville in California to Oshkosh in Wisconsin. There they teamed up with Jack Peterson and Pat Hirst, who had already flown to Oshkosh with their own Pfledges from Los Angeles on the West coast, and flew on to Kitty Hawk on the East Coast - the first transcontinental flights in the history of ultralights. The destination was chosen in honour of Orville and Wilbur Wright, who took off from Kitty Hawk in their famous Flyer back in 1903. This first transcontinental Pfledgling is now on show in the Smithsonian National Air & Space Museum in America.
The Pfledge prides itself on being the first American ultralight with 'all-terrain' capabil-ity, thanks to its tricycle undercarriage with large wheels and efficient suspension. Initially fitted with a Zenoah engine, the airframe underwent various modifications during the course of summer '79, acquiring a Sachs 340 cc engine, the resulting machine being dubbed Pfledgling OR (Oshkosh Replica) , a high performance, double surfaced beast based on the Fledgling rigid-wing hang glider. It was this variant that Jack McCornack and Keith Nicely used on their transcontinental flight.

The next modification was to fit a twin-cylinder Cuyuna 430D (without reduction drive), this model coming out the same year with the name Pfledgling 430D. The wing used was the Manta Fledge II B.

A hybrid-control machine, the Pfledge has a swing seat which allows the pilot to control pitch by weight-shift. The original aircraft and its OR derivative used a twist-grip for each rudder, one either side of the pilot on each main horizontal tube, but for the 430D Pterodactyl substituted a single side-mounted stick.

Although the Pfledgling OR was still available in 1983, the company is not actively marketing it and does not quote a price. The mainstream Pfledge now is the 430D which is sold as a kit, a 40-60 h assembly time being claimed. In addition to power pack and airframe, the kit comprises seat, shoulder harness, storage covers (the aircraft is car-toppable), ASI and altimeter. Price: $4547.

The Pfledgling NFL was produced at a time when US law required all ultralights to be foot-launchable (theoretically at least!), the NFL was as its title suggests Not Foot Launchable and was aimed at the experimental aircraft market. It consisted of a Pfledgling 430D with an elevator added, carried on two booms behind the frame, where it was exposed to the propwash. A fixed seat replaced the swing seat of the ffledgling 430D, the NFL thus becoming the first Pterodactyl with two-axis rather than hybrid control. Though not many of this now-obsolete model were sold, the NFL is significant because it paved the way for the Ptraveler.
The Acro-Dactyl is the result of development work carried out in the summer of 1981, when Pterodactyl undertook trials on two specially reinforced Pfledglings, designed for elementary aerobatics.

Pfledgling 430D

Engine: Cuyuna 430D, hp at 5500 rpm
Propeller diameter and pitch 36 x 16 inch, 0.91 x 0.41 m
No reduction
Max static thrust 165 lb, 75 kg
Power per unit area 0.19hp/sq.ft, 2.0 hp/sq.m
-Fuel capacity 2.5 US gal, 2.1 Imp gal, 9.5 litre
Length overall 10.0 ft, 3.05 m
Height overall 9.1ft, 2.77m
Wing span 33.0ft, 10.06m
Chord at root 5.5ft, 1.65m
Chord at tip 4.5 ft, 1.34 m
Total wing area 162 sq.ft, 15.1 sq.m
Wing aspect ratio 6.7/1
Nosewheel diameter overall 14 inch, 36 cm
Main wheels diameter overall 20 inch, 51 cm
Empty weight 165 lb, 75 kg
Max take-off weight 425 lb, 193kg
Payload 260 lb, 118 kg
Max wing loading 2.62 lb/sq.ft, 12.8 kg/sq.m
Max power loading 14.2 lb/hp, 6.4kg/hp
Load factors; +4.4, -3.3 ultimate
Max level speed 55mph, 88kph
Never exceed speed 55mph, 88 kph
Max cruising speed 45 mph, 72 kph
Economic cruising speed 35mph, 56kph
Stalling speed 23 mph, 37 kph
Max climb rate at sea level 400 ft/min, 2.0 m/s
Min sink rate 400ft/min, 2.0m/s
Best glide ratio with power off 9/1
Take-off distance 125 ft, 38 m
Landing distance 100 ft, 30 m
Service ceiling 15,000 ft, 4570 m
Range at average cruising speed 125 mile, 201 km

 

 


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