What was the Airfoil of Handley Page P.115?
Did you see what Wikipedia had for it, and the book it came from?


  Specifications (HP.115)
  Data from X-Planes and Prototypes: From Nazi Secret Weapons to the Warplanes of the Future [Winchester 2005, p. 134]
  
  General characteristics
  
  Crew: one
  
  Length: 50 ft 4 in (15.33 m)
  
  Wingspan: 20 ft (6.1 m)
  
  Height: 12 ft 9 in (3.9 m)
  
  Wing area: 432 ft² (40.1 m²)
  
  Airfoil: Bicon 6%
  
  Empty weight: 3,680 lb (1,670 kg)
  
  Useful load: (Fuel) 1,175 lb (533 kg)
  
  Loaded weight: 5,050 lb (2,291 kg)
  
  Powerplant: 1 × Bristol Siddeley Viper BSV.9 turbojet, 1,900 lbf static (8.455 kN)
  Performance
  
  Maximum speed: 248 mph (399 km/h)
  
  Endurance: 40 minutes


This paper goes into calculations on biconvex airfoil as well, interesting reading  https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930085007.pdf