In 1938 Jack Laister completed a gull-wing sailplane, which was referred to as the Lawrence Tech Sailplane after its sponsor. Repainted red, white and blue and renamed the ‘Yankee Doodle’ it competed in a 1939 aerobatic competition at the Paris airshow.

With the need for military trainers on the outbreak of World War II, Laister designed the two-place Yankee Doodle 2 from the original that utilized some of the features and technology from the LT-IV but transitioned to a dual cockpit and straight wing arrangement.

A flat-top Version with increased performance also has an ATC. A ‘bunnynose’ LK, flown by Harold Hutchinson, held the national multiplace goal record of 399 km/ 248 miles from 1956 to 1967.

The Vintage Sailplane Association has copies of the military manuals, color scheme drawings and paint chips available.

One LK-10A belongs to the National Soaring Museum.

LT IV
Wing Span: 14.173 m
Wing Area: 12.5 sq m
Structure Weight: 124.7 kg
Flying Weight: 214.3 kg
Wing Loading: 17.14 kg/sq m
Root Chord: 137.2 cm
Tip Chord: 50.8 cm
Aspect Ratio: 16
Fuselage Length: 5.867 m
Stabilizer Span: 269.2 cm

LK-10A
Wing span: 15.2m /50ft
Wing area: 13.33sq.m / 165sq.ft
Empty Weight: 215kg / 475lb
Payload: 181kg / 400lb
Gross Weight: 396kg / 875lb
Wing Load: 29.7kg/sq.m / 5.27lb/sq.ft
L/DMax: 22 89 kph / 45 kt / 55 mph
MinSink: 0.98 m/s / 3.2 fps / 1.90 kt
Aspect ratio: 15.1
Airfoil: NACA 4418, 4409
Seats: 2
No. Built: 156

The LP-49, popularly known as the ‘Forty Niner’, is a Standard Class single-seater that was first rolled out in prototype form, designated LP-46, on 4 July 1966. It is of metal and glassfibre construction, but designed to be sold in kit form for the amateur constructor, and more than 50 LP-49 kits had been sold by early 1976, about 35 of which had been completed and flown.

The high cantilever wings are of laminar flow section, the extruded aluminium main spar booms being curved in a chordwise direction to follow the aerofoil section; the roll contoured aluminium sheet wing skin is butt jointed and flush riveted with blind pop rivets. The semimonocoque fuselage is made up of two premoulded glassfibre halves joined over aluminium bulkheads and fittings. The tail unit is of aluminium with a swept back fin and rudder, and the landing gear consists of a shock- strutted retractable monowheel with a brake and a glassfibre nose skid with a steel shoe; a fixed shrouded tailwheel replaces the retractable tailwheel of early production aircraft. The LP-49 has an automatic aileron and dive-brake control hookup and internal control- surface counterweights.

The ship is approved for spins, loops and wing-over, and has been static tested to 12 g. The LP-49 was sold in both kit form and as a complete, ready-to-fly sailplane.

Jerry Haynes
haynesja@yahoo.com
Need help to find Stabilizer ? Elevator / pictures / drawings to build a new tail group

LP-46
Span: 13.56 m. / 44.5 ft.

LP-49
Span: 15.0 m / 49 ft 2.5 in
Length: 20 ft 7.25 in
Wing area: 13.29 sq.m / 143 sq ft
Aspect ratio: 16.9
Airfoil: NACA 64(3)-618
Empty Weight: 215 kg / 475 lb
Gross Weight: 408 kg / 900 lb
Payload: 125 kg /275 lb
Water ballast: None
Max wing loading 30.72 kg/sq.m / 6.29 lb/sq ft
Max speed: 135 mph /117 kt / 217 km/h
Stalling speed: 30 kt / 56 km/h
Max rough air speed: 117 kt / 217 km/h
Min sinking speed: 0.63 m/sec / 2.07 ft/sec at 50 mph / 43 kt / 80 km/h
Best glide ratio: 36.5:1 at 58 mph / 50 kt / 92.5 km/h
No. of Seats: 1
No. Built: 53

Laister-Kauffman Aircraft Corp was later succeeded by Laister Sailplanes Inc and in 1970 Jack Laister and his son Bill, an aerodynamicist, started design work on the LP-15 Nugget Standard Class single-seater of metal construction.

It is a cantilever shoulder-wing monoplane with a T-tail and long-span flaps which are raised slightly for high speed flight, are lowered 8° for soaring in thermals and can be extended to 85° for use as air brakes. Up to 185lb of water ballast can be carried on the center of gravity. The wings and top-hinged plain ailerons are of Chem-Weld bonded aluminium alloy construction, while the semi-monocoque fuselage has the forward portion of moulded glassfibre and the rear part of bonded aluminium alloy construction which incorporates the swept fin. Landing gear consists of a retractable monowheel and the pilot sits in a semi-reclining seat under a two-piece canopy with a removable section and a sliding ventilation panel.

They decided to wait for the recommendations of the CIVV conference on Standard Class requirements before starting construction of the prototype in February1971, and this first flew in June that year, its maiden flight also being a contest flight; the Nugget was certificated in mid-1975.

The ship was available only as a factory-built product and 15 were built. One Nuget belongs to the National Soaring Museum.

Wingspan: 15.0 m / 49 ft 2.5 in.
Wing area: 10.13 sq.m / 109 sq.ft
Airfoil: Wortmann FX 67170/150
Wing aspect ratio: 22.2
Length: 6.1 m / 21 ft
Height: 1.27 m / 4 ft 2 in
Gross Weight: 408 kg / 900 lb
Empty Weight: 193 kg / 425 lb
Wing loading: 40.27 kg/sq.m / 8.26 lb/sq ft
Payload: 215kg / 475lb
Water Ballast: 84 kg / 185 lb
Max airspeed: 135 kts 126 kt / 233 km/h
Rough air speed: 126 kt / 233 km/h
Stall: 34 kt / 63 km/h
Lift to drag: 37 at 93 kph / 50 kts / 58 mph
Sink: 0.66 m/s / 2.16 fps / 1.29 kt at 43 kts
Seats: 1