|
|
1. The X Van lifts off vertically in the tail-sitting attitude from its
specialized launch and recovery apparatus: "LARA." Normal launch uses only
the four Rybinsk Motors' RD-38 airbreathing lift engines -- plus 20 seconds
of thrust from small takeoff assist/abort engines. "Zero-launch" in an inclined
attitude is an option. Subject to noise, exhaust erosion, reentry sonic
boom, and regulatory restrictions, the X Van can operate from almost
any type of site -- including a small island or a stable sea platform.
|
|
2. On a normal flight, the X Van climbs subsonically
to an altitude of about 10 km, using only its wings and thrust from the four
RD-38 engines. At this point, the main rocket engines are started in a low-thrust
mode, and a pull-up is made to about a 30 degree flight path angle. The RD-38
engines are then shut down and the inlets are closed.
|
|
3. The main rocket engines are throttled up to full power and the pull-up
is continued to about a 50 degree flight path angle.
|
|
4. Burnout occurs at an altitude of about 50 km and a velocity of about
1230 m/s.
|
|
5. After burnout, the X Van continues to coast up to an apogee just above
100 km.
|
|
6. The X Van establishes an angle of attack of about 30 degrees at an
altitude of about 65km and a speed of about 1110 m/s to prepare for reentry.
The X Van has experienced about 185 seconds of near zero-g, and aerodynamic
forces are still very low at this point. About 20 seconds later -- at an
altitude of about 45 km -- velocity has increased to about 1250 m/s
(mach 3.8) and total g's have built up to about 0.5 g. Peak velocity of about
1285 m/s occurs about 10 seconds later at an altitude of about 37 km. Total
g's have built up to about 1.8, and mach number has increased to about 4.1.
About 15 seconds later, g's have built up to about 4 g's, and the angle of
attack is decreased to maintain total acceleration forces at about 4 g's
for the rest of the pullout. The X Van is still supersonic at the end of
pullout at an altitude of about 11 km. Further deceleration occurs in a
climb.
|
|
7. During reentry, the X Van begins a gliding turn back toward the launch
site.
|
|
8. After reaching subsonic speed at an altitude of about 12,500 meters,
the RD-38 engines are restarted for continued glide and short cruise back
to the launch site. The RD-38 is designed to operate only in the vertical
attitude. A derivative engine, the RD-38A, is designed to operate only in
the horizontal attitude. Operation in both attitudes will require modification
of the fuel feed system to the RD-38.
|
|
9. As the X Van nears the launch/recovery site, it pulls up to a vertical
attitude at low altitude in close proximity to the LARA.
|
|
10. The X Van then lines up with the cable line on the LARA, in order
to engage this cable with a hook extended from the nose just in front of
the cockpit. Normally, the hover and hookup maneuver will require about 20
seconds or less. However, the X Van will have recovery fuel sufficient for
about 2 minutes of hover.
|
|
11. After hookup, special devices on the LARA will latch on to the hard
support points at the end of the vertical and horizontal fins. A cradle will
then support the X Van's fuselage and the X Van will be rotated to the horizontal
postion for easier crew/passenger access and maintenance. In an emergency
condition with light winds, the X Van may be able to land on extensions from
the vertical and horizontal fins. However, this maneuver is quite disorienting
to the pilot compared to engaging the hook in front of the cockpit. Moreover,
landing gear designed to prevent tipover would be quite large and heavy.
|
|
12. After maintenance and other turnaround items -- including refueling
and rocket propellant replenishment -- the crew and simulated passengers
will climb aboard, and the X Van will be rotated for the next launch. At
launch, all parts of the LARA are positioned out of the way, and the X Van
is supported only by the clamps at the end of the vertical and horizontal
fins.
|