Natural Science Forum / Physics / General Physics / July 2008

With little or no (POGO or TO) vibration :

http://webpages.charter.net/tsiolkovsky/

http://webpages.charter.net/tsiolkovsky/DeltaV_Flight_Instructions.txt

Delta V Flight Instructions

This addon is zipped from the root directory, so just unzip into your
presumably functional Orbiter Space Flight Simulator directory, and the
files should unzip into the correct locations.

The supplied mp3 runs for the duration of the six minute flight should
be unzipped into your Orbitersound mp3 directory, with the proper
settings (OrbiterSound in all views, no mp3 playlist or any other mp3s
present in the mp3 directory, for instance.)

Turn on your Orbiter force vectors (cntl-F9, Tab to Forces, and then
check all the boxes)

The Delta V is extremely simple to fly with no rotational drag. Just
launch with cntl-+ and wait for the vehicle to clear the pad, and then
after a few seconds, use cntl-uparrow to apply a one second burst of
pitch thrust, to start the vehicle into slow pitch motion. Use F1 to
switch between flight view and cockpit view, and keep an eye on your
altitude. Your drag vector should appear, and drag start increasing, and
when you reach approximately 8 kilometers of altitude, apply continuous
pitch thrust with cntl-+ to start pitch acceleration. You should be at
approximately five degrees from vertical at this point, and certainly no
more than 10 degrees.

Drag will max out, and then begin dropping, and then begin climbing
again as you accelerate upwards. Drag should drop off as you approach 45
degrees of pitch and turn over. This is roughly the point at which your
Falcon 1 boosters fall off (170 seconds) if you've attached any.

Continue pitch acceleration until the vehicle reaches 45 degrees pitch,
and then quickly reverse pitch to cntl-downarrow. This should occur at
roughly 30 kilometers. Continue pitch reverse acceleration until the
vehicle reaches a pitch of 10 degrees above the horizon, and then quit
pitch steady at 10 degrees and with for your momentum vector to catch up
with your pitch. Stop pitch should occur at roughly 50 kilometers altitude.

Keep an eye on your acceleration, and when your momentum vector starts
to catch up with your pitch, apply another one second burst of pitch
with cntl-up arrow, to begin your slow drift down to the horizon. You
don't want to actually reach the horizon at engine cutoff, though,
because you still want to ascend to apogee.

As acceleration passes through 3 gees (30 m/s^2) begin throttle back
with short bursts of cntl-minus (-).

As the vehicle slowly drifts from 10 degrees pitch to five degrees of
pitch, throttle back intermittently, keeping acceleration at or just
above 3 gees (30 m/s^2). This throttle back operation will begin to
occur at roughly 70 kilometers of altitude.

Once the SSME throttle stop is reached at 1.52 MegaNewtons (MN) of
thrust, discontinue throttle back. This is your minimum thrust limit.
Switch from global frame to absolute direction with two taps of the F2
key. You should now have an excellent view of the Bahamas passing by on
the starboard side of the craft, or simply in the background.

You should be passing through 85 kilometers at this point, and five
degrees pitch above the horizon. Discontinue slow pitch with a short
burst or bursts of cntl-down arrow, and fine adjust as necessary.

Continue monitoring acceleration and pitch, you should be approaching
100 kilometers at five degrees pitch or less, with your momentum vector
at three degrees or so above the horizon and you should be at 7000 m/s
and seven gees very shortly. You need to watch these values closely.

As acceleration exceeds 7.5 gees (75 m/s^2) and relative velocity
exceeds 7500 meters per second, quickly shut down the space shuttle main
engine with cntl-*, with your altitude at or above 100 kilometers. How
far above 100 kilometers you are at engine cutoff, and how far above the
horizon your momentum vector is, determines how much drag will erode
your final apoapsis value, usually dropping off by a few kilometers.
Ideally you want to keep this loss to zero, which is higher than about
115 kilometers. Your final residual fuel value will be 2.2 to 2.5
percent, depending on your final apoapsis and velocity. Ideally you also
want to keep your momentum vector pinned to your pitch vector, but this
is often not possible in practice.

For any particular orbit or apoapsis besides straight east from Cape
Canaveral, use your Launch MFD. This is a particularly simple way to get
to your equatorial spaceport or Hubble station.

The use of multiple Falcon 1 type launch assist boosters will drop the
terminal gee forces at main engine cutoff down to a more reasonable
range of five to six gees, and further reductions in terminal gee forces
may be achieved by lowering the throttle stop of the SSME or by varying
your throttle back acceleration profile. Thirty percent throttle yields
a 3 gee maximum force, but will require an entirely more modern engine.

Launch profile optimization algorithms in real world simulations which
accurately model environmental conditions and structural limitations,
will reveal subtle variations from this intrinsically fundamental high
energy cryogenic fight profile, which has been developed to reach low
earth orbit with the minimum amount of fuel and the maximum amount of
payload (the vehicle).

Enjoy your flight. You paid for it.