Engineering:Laister-Kauffman TG-4

TG-4, LK-10
TG-4A in the National Museum of the United States Air Force
Role	Sailplane
National origin	United States
Manufacturer	Laister-Kauffmann
Designer	Jack Laister
Number built	153
Developed from	Yankee Doodle
Variants	Bartos/Nobel BN-1 Phantom

The Laister-Kauffmann TG-4 (designated LK-10 Yankee Doodle 2 by its designer) was a sailplane produced in the United States during the Second World War for training cargo glider pilots. It was a conventional sailplane design with a fuselage of steel tube construction and wooden wings and tail, covered all over with fabric. The pilot and instructor sat in tandem under a long canopy.

Design and development

Jack Laister designed the aircraft in response to the formation of the United States Army Air Corps' American Glider Program in 1941, basing it on his Yankee Doodle design of 1938 for Lawrence Tech. Aside from the addition of a second seat, the Yankee Doodle 2 differed from its predecessor by having wings of constant dihedral instead of gull wings. The USAAC expressed interest, but only if Laister could arrange for the manufacture of the type. When Laister found a sponsor in businessman John Kauffmann, they established the Laister-Kauffmann Corporation in St Louis, Missouri and the USAAC ordered three prototypes as the XTG-4.

When evaluation of the type proved positive, the Army placed an order for 75 aircraft, followed by an order for another 75. These were operated as the TG-4A. All had been withdrawn from service prior to the end of the war when it was discovered that the flight characteristics of the aircraft were so different to those of a cargo glider, that the experience gained on the TG-4 was not particularly relevant. After the war many were sold as surplus and helped build civilian gliding in the USA.

Variants

• XTG-4 - prototypes (three built)
• TG-4A - production model (150 built)
• TG-4B - civilian aircraft impressed into service (one impressed)

Operators

LK-10 Serial #48 registered as N53619 owned and flown by Doug Fronius of Poway, California, USA as of 2023. Based at Mountain Valley Airport in Tehachapi, California.

LK-10 Serial #106 under prefix PT-PAZ operated by Aeroclube de Bauru in Brazil as of April 2013

Laister-Kauffman TG-4 PT-PAZ in Bauru, Brazil

This glider crashed on March 10, 2020.

LK-10 Serial # unk operating at Rockton, Ontario (CF-AZJ) as of Apr, 2022

TG-4 on display at the Museum of Aviation

LK-10 Serial #23 formerly registered as N53609 currently under restoration to flying condition in Dayton, Ohio, USA as of 2023. Once restored the aircraft will be based at the Caesar Creek Soaring Club in Waynesville, Ohio.

Aircraft on display

• 42-43688 – TG-4A on static display at the Planes of Fame in Chino, California.
• 42‐43734 – TG-4A on static display at the National Museum of the United States Air Force in Dayton, Ohio.
• 42-43740 – TG-4A on static display at the Museum of Aviation at Warner Robins Air Force Base in Warner Robins, Georgia.
• 42-53078 – TG-4A on static display at the Air Mobility Command Museum at Dover Air Force Base near Dover, Delaware.
• 42-437357 – TG-4A on static display at the National Soaring Museum in Elmira, New York.
• 

  TG-4 at the Silent Wings Museum.
  42-530727 – TG-4A on static display at the Silent Wings Museum in Lubbock, Texas.
• 28 – TG-4A on static display at the US Southwest Soaring Museum in Moriarty, New Mexico.
• 71 – TG-4A on static display at the Southern Museum of Flight in Birmingham, Alabama.
• 42-53072 – TG-4A on static display at the Military Aviation Museum in Virginia Beach, Virginia.
• LK-10A on static display at the Historic Aircraft Restoration Museum in Maryland Heights, Missouri.
• LK-10A on static display at the Port Townsend Aero Museum in Port Townsend, Washington.
• USAAF 84.42-53027 at Gliding Heritage Centre

Specifications (LK-10 / TG-4A)

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

General characteristics

• Crew: 2
• Length: 21 ft 4 in (6.5 m)
• Wingspan: 50 ft 0 in (15.24 m)
• Height: 3 ft 7.9 in (1.115 m) at cockpit
• Wing area: 164 sq ft (15.2 m²)
• Aspect ratio: 15.1
• Airfoil: root – NACA 4418, tip – NACA 4409
• Empty weight: 476 lb (216 kg) equipped
• Gross weight: 875 lb (397 kg)

Performance

• Stall speed: 38 mph (61 km/h, 33 kn)
• Never exceed speed: 126 mph (203 km/h, 110 kn)
  
• Rough air speed max: 203 km/h (126.1 mph; 109.6 kn)
• Aerotow speed: 203 km/h (126.1 mph; 109.6 kn)
• Winch launch speed: 130 km/h (80.8 mph; 70.2 kn)
• g limits: +6 -3 at 225 km/h (139.8 mph; 121.5 kn)
• Maximum glide ratio: 22 at 80 km/h (49.7 mph; 43.2 kn)
• Rate of sink: 191 ft/min (0.97 m/s) at 73 km/h (45.4 mph; 39.4 kn)
• Wing loading: 5.4 lb/sq ft (26.5 kg/m²)

See also

Aircraft of comparable role, configuration and era

• DFS Kranich

Related lists

• List of gliders

References

• Shenstone, B.S.; K.G. Wilkinson (1963) (in en, fr, de). 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. 160–162. 
• US Southwest Soaring Museum (2010). "Sailplanes, Hang Gliders & Motor Gliders". http://swsoaringmuseum.org/collection.htm. 

Further reading

• Taylor, Michael J. H. (1989). Jane's Encyclopedia of Aviation. London: Studio Editions. pp. 563. 
• Salmi, Reino J. (March 1943). "Gliders for Victory". The Wisconsin Engineer 47 (6): 8–9. http://digicoll.library.wisc.edu/cgi-bin/UW/UW-idx?type=div&did=UW.WIEV47NO6.RSALMI&isize=text. Retrieved 2008-09-16.  (uncorrected OCR)

External links

• Laister-Kauffmann TG-4A – National Museum of the United States Air Force
• Sailplane Directory entry on the LK-10
• LTU timeline
• Air Mobility Command museum
• Aircraft/laister-kauffman_tg-4a.htm Museum of Aviation
• The Air Mobility Command Museum