Engineering:Marske XM-1

Short description: American glider

XM-1
The XM-1 in its original configuration with tip rudders
Role	Glider
National origin	United States
Designer	Jim Marske
First flight	1957
Status	Sole example no longer on FAA registry
Number built	one

The Marske XM-1 was an American mid-wing, single-seat, experimental tailless glider that was designed and built by Jim Marske in 1957.

Experimentation with the XM-1 lead to the final configuration of the later Marske Pioneer.

Design and development

The first of Marske's flying wings was the XM-1, a design inspired by the flying wing designs of Charles Fauvel and Al Backstrom. He built the XM-1 when he was 19 years old. The aircraft went through several versions, each a modification of the same basic airframe as Marske experimented with configurations. The aircraft started off with fins on the wing tips and was later converted to a single fin at the rear of the short fuselage in its "XM-1D" configuration.

The XM-1 was built with a welded steel tube fuselage covered in fiberglass. The 40 ft (12.2 m) wing was fabricated from wood and covered with doped aircraft fabric. The wing employed a 14% Fauvel airfoil. The landing gear was a fixed monowheel.

Only one XM-1 was built. It was registered with the US Federal Aviation Administration in the Experimental - Amateur-built category.

Operational history

The XM-1 was described by Soaring Magazine as "easy to fly". The aircraft was stall and spin proof. Marske sold the aircraft and it went through a series of owners. The XM-1 was later removed from the FAA register and likely no longer exists.

Variants

The XM-1 in its "D" configuration with the single central fin and rudder

XM-1-A

Initial configuration with wing tip fins and rudders.

XM-1-B

with minor improvements over the XM-1-A

XM-1-C

Modified with a central fin only.

XM-1D

Final configuration with a central fin and rudder.

Specifications (XM-1B)

Data from The World's Sailplanes:Die Segelflugzeuge der Welt:Les Planeurs du Monde Volume II

General characteristics

• Crew: one
• Length: 8 ft 2 in (2.48 m)
• Wingspan: 38 ft 1 in (11.6 m)
• Height: 3 ft 10 in (1.16 m) at cockpit
• Wing area: 160 sq ft (15 m²)
• Aspect ratio: 9
• Airfoil: 14% Fauvel
• Empty weight: 311 lb (141 kg)
• Gross weight: 551 lb (250 kg)

Performance

• Never exceed speed: 140 mph (226 km/h, 122 kn)
  
• Aerotow speed: 104.5 mph (90.8 kn; 168.2 km/h)
• Winch launch speed: 105 km/h (65.2 mph; 56.7 kn)
• g limits: +4 -3 at 65.25 mph (56.7 kn; 105.0 km/h)
• Maximum glide ratio: 24:1 at 51 mph (44.3 kn; 82.1 km/h)
• Rate of sink: 175 ft/min (0.89 m/s) at 39.8 mph (34.6 kn; 64.1 km/h)
• Wing loading: 3.4 lb/sq ft (16.7 kg/m²)

See also

Related lists

• List of gliders

References

• Shenstone, B.S.; K.G. Wilkinson (1963) (in English, French, German). The World's Sailplanes:Die Segelflugzeuge der Welt:Les Planeurs du Monde Volume II (1st ed.). Zurich: Organisation Scientifique et Technique Internationale du Vol a Voile (OSTIV) and Schweizer Aero-Revue. pp. 226–227. 
• Rogers, Bennett (August 1974). "1974 Sailplane Directory, Soaring Magazine". Soaring Magazine (Soaring Society of America): 96. 
• Federal Aviation Administration (August 2011). "Make / Model Inquiry Results". http://registry.faa.gov/aircraftinquiry/AcftRef_Results.aspx?Mfrtxt=MARSKE&Modeltxt=&PageNo=1. Retrieved 6 August 2011. 
• Marske, Jim (n.d.). "The Flying Wings of Jim Marske". http://www.marskeaircraft.com/flyingwings.html. Retrieved 20 March 2011. 
• Marske, Jim (n.d.). "About Jim Marske". http://www.marskeaircraft.com/aboutus.html. Retrieved 20 March 2011.