title: Martin XLB-4
text: # Martin XLB-4
  
  The Martin XLB-4 was a 1920s proposal for a light bomber by the Glenn L. Martin Company.
  
  ## Design and development
  
  The XLB-4 would have been a biplane bomber of all metal construction, powered by two Pratt & Whitney R-1690 Hornet radial engines. The United States Army Air Corps (USAAC) ordered a single prototype serialled 27-332, but the aircraft was cancelled because the USAAC leadership was lukewarm about experimenting with all-metal aircraft.
  
  ## Specifications (XLB-4 estimated)
  
  General characteristics
  
  * Crew: 5
  * Length: 44 ft 8 in (13.61 m)
  * Wingspan: 76 ft (23 m)
  * Height: 16 ft 7 in (5.06 m)
  * Wing area: 1,203.0 sq ft (111.76 $m^2)$
  * Empty weight: 5,891 lb (2,672 kg)
  * Gross weight: 11,982 lb (5,435 kg)
  * Powerplant: 2 × Pratt & Whitney R-1690 Hornet 9-cylinder air-cooled radial piston engines, 525 hp (391 kW) each
  
  Performance
  
  * Maximum speed: 69 mph (111 km/h, 60 kn)
  * Wing loading: 9.98 lb/sq ft (48.7 $kg/m^2)$
  