From a Paul Czysz paper in: "Scramjet Propulsion" (Cuirran and Murthy editors), Paul
discusses the McDD concept shown in the second picture:
"The resulting aircraft rather resembled the Canadian CF-106 Arrow (CF-105 actually) with very large inlets
and did not offer a significant research value with regard to fully integrated propulsion systems."
and then a little later - a very interesting observation - and RASCAL
was going in this direction, somewhat. Quoting Mr. Czysz again:
"All the afterburning turbojet/fans used in the HyFac study were conventional installations
where the airflow to the compressor increased in temperature and pressure. At about Mach
number 1.8, most compressors reach the point where the corrected speed for design efficiency
equals the machanical rotational speed limit of the compressor. At Mach numbers above this
point the mechanical speed is constant and the corrected compressor speed (N/sqrt(T/288K)
decreases. If there is a cryogenic heat exchange in the inlet between the inlet exit and
compressor entrance, then the temperature of the air entering the compressor can be kept at
that for best corrected speed, up to the Mach number limit where the heat exchanger can no
longer keep the temperature within limits. When such a turbojet is thermally integrated with a
rocket, there is no longer a transonic acceleration deficiency. This is not a classic definition of
a turbojet." I may also add, this is similar to what skylon is doing.
Were any these your possible RASCAL refs:
http://www.responsivespace.com/Papers/RS2%5CSESSION%20PAPERS%5CSESSION%208%5CLOPATA%5C8004P.pdf
http://smartech.gatech.edu/bitstream/1853/8372/1/AIAA-2005-3241.pdf
