Heij,
The concept has been studied by NASA in the early 60s:
Tecnical report NASA TM-X-893, dated Oct. 1963:
"Longitudinal stability and aerodynamic characteristics of a reentry vehicle configuration having an extendable leading edge at a Mach number of 10.03 and angles of attack from 50 deg to 90 deg"
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19720065666_1972065666.pdf
Cheers,
Philippe