Aerostructure PLM 80
Single-seat single-engined mid-wing monoplane with conventional three-axis control. Wing has swept forward leading and trailing edges, and tapering chord; T-tail. Pitch control by elevator on tail; yaw control by fin-mounted rudder; roll control by one-third span ailerons; control inputs through stick for pitch/roll and pedals for yaw. Cantilever wing; wing profile Worthmann FX 66SA96 V1; double-surface. Undercarriage has two wheels in tandem with wing-tip skids and tailskid; no suspension on any wheels. Push-right go-right tailwheel steering connected to yaw control. Brake on main wheel. Glass-fibre fuselage, totally enclosed. Engine mounted above wing driving pusher propeller.
The designation PLM80 clearly shows that this aircraft is what the French call a planeur leger motorise, which translates as motor glider rather than microlight. The prototype has hardly completed its first flights and exceeded most countries' definition of a microlight. In 1982, this latest product from Aerostructure was being test flown with a view to conventional certification.
Its structure is made entirely of glass-fibre laminates, as with all modern conventional gliders, and the PLM80 has a Worthmann FX66S-196V1 profile, set at 1½ degrees incidence and with the maximum coefficient of lift of 1.5. The drag coefficient 0.45. The wing is also fitted with air brakes, totalling 1.79 sq.ft (0.166sq.m) in surface area and which can travel from + 16 to -21%. The T-tail uses Worthmann FK71L 150/42.5 profiles vertical fin and 150/30 for the horizontal, with the latter installed at -2.5% incidence.
The engine is also a prototype, the three -cylinder French PAL640 from JPX, which was on static show at the end of July 1982 at Brienne le Chateau, the annual convention for European homebuilders. At that time it had just completed its bench testing. It drives a three-bladed propeller directly, of fixed pitch and 37 inch (0.93 m) diameter.
Engine: JPX PAL640, 32 hp at 4600 rpm.
Propeller diameter: 37 inch, 0.93 m.
Power per unit area: 0.46 hp/sq.ft, 5.0 hp/sq.m.
Empty weight: 353 lb, 160kg.
Max take-off weight: 618 lb, 280kg.
Payload: 265 lb, 120kg.
Max wing loading: 8.95 lb/ sq.ft, 43.8 kg/sq.m.
Max power loading: 19.3 lb/hp, 8.8kg/hp.
Load factors: +8.0, -4.0 ultimate.
Length overall: 16.7 ft, 5.1 m.
Height overall: 3.5ft, 1.04m.
Wing span: 36.1ft, 11.0m.
Chord at root: 2.7ft, 0.8m.
Chord at tip: 1.2ft, 0.35m.
Dihedral: 4 degs
Sweep forward: 3.5degs
Tailplane span: 5.9 ft, 1.8 m.
Fin height: 3.4ft, 1.0 m.
Total win area: 69 sq.ft, 6.4 sq.m.
Total aileron area: 9.1 sq.ft, 0.85 sq.m.
Fin area: 6.5 sq.ft, 0.6 sq.m.
Rudder area: 2.7 sq.ft, 0.25 sq.m.
Tailplane area: 7.8 sq.ft, 0.72 sq.m.
Total elevator area: 2.3 sq.ft, 0.22 sq.m.
Wing aspect ratio: 18.9/1.
Tailwheel diar overall: 8 inch, 20 cm.
Main wheel dia overall: 12 inch, 30 cm.