Arrow-Flite of Michigan Whitney Porta-Wing
The Whitney Porta-Wing spars are in 4 ft lengths with aluminium sleeves which allows it to be disassembled in 10 minutes to a 5 ft package. A cable leading edge forms a cylindrical edge shape to give a gull dihedral for more lift.
The airframe consists of a keel and a wing spar that are kept under compression by a cable around the perimeter. Tubing is 2in x .058 6061-T6 anodised aluminium, reinforced with internal bushings. Sleeves are quad-spaced pop riveted into the main tubes.
All rigging is 3/322in 7 x 7 aircraft quality. At the cable leading edge the wire rope is sleeved with “Eastman” plastic tubing. Double swagged throughout. All fasteners are grade 8 and thimbles are stainless steel, except heavy galvanised at the wing tips. Tangs are machined from stainless steel. Turnbuckles are polished bronze. All nuts and pins are aircraft quality. The sail is double zig-zag stitched from 3.8oz Bainbridge stabilised dacron. Critical areas are reinforced.
A swing seat was provided with 3/32in wire rope. The harness included sheathed tubing over the cables. Armaflex sleeves were on the control bars.
A low aspect ratio glider, it folds down into a small package 5ft x 1ft.
Leading edge: 18 ft
Keel length: 16 ft
Wing span: 26 ft
Wing area: 208 sq,ft
Aspect ratio: 1.6
Nose angle: 135˚
Sail billow: varies˚
Weight: 35 lb
Pilot weight: 140-220 lb
Takeoff speed: 5-7 mph
Stall speed: 4-5 mph
Max speed: 20 mph
Best glide ratio (L/D): 4-1
Best L/D speed: 15 mph