Flight Question TORF in Shuttle Fleet 4.8

[spartanhoplite15]

Hello,

I have had trouble with the TORF (Twice Orbital Rate Fly-around) after undocking from the ISS. How could I do a good TORF using the RPOP MFD? Is UNIV PTG MFD related to it? Please, try to explain in-depth as possible

Any help would be appreciated.

 

[zerofay32]

This maneuver uses orbital mechanics to work, so a general understanding of orbital mechanics will be helpful. :thumbup:

I haven't done this in a while but I try to give you an explanation.

First, while still docked to the station, the ISS should be 'wings level' to the horizon and have the PMA facing the direction of flight. (or if you like, the Russian modules are facing away from the direction of flight) The shuttle should be nose zenith, with the payload bay facing retrograde. The station should be rotating to keep this attitude (the exact value on UNIV PTG will be around -0.65 to -0.7 depending on your orbit [I'm not certain if this number will be positive or negative])

(See attached picture throughout explanation)

Now that the station is positioned correctly, its time for undocking. This was timed to occur fifteen to thirty minuets before orbital sunrise. At this point, undock the shuttle. Keep the station centered in the docking camera. This will require +X thrusters and the shuttle should still be rotating at orbital rate.

Once outside of 500 ft from the station on the +VBAR fire +Z thrusters to null the rate between the shuttle and station and stationkeep untill sunrise. (3)

After sunrise, to start the TORF, Pitch up to Twice Orbital Rate. (this will be either +-14 or the reciprocal of what your orbital rate was. Again, its been awhile for me I'm 80% sure its the reciprocal) Then thrust -X to start the fly-around. What I do, is I watch the station through the overhead window and null any apparent motion, but do not touch the rotation rate. As you rotate, you will need to apply +Z thrust to remain around 500 to 700 feet from the station. The attachment shows the TORF ending under the station at the +RBAR, but later missions continued past the +VBAR to the -RBAR before leaving the station with a retrograde RCS burn (Completing one and a quarter revolutions around the station.

A NOTE ON RPOP MFD - This MFD works best if you are using David413's ISS Fleet. It can be used for distance info with other addons though.

ATTITUDE MDF has a Twice Orbital Rate hold feature. may be worth looking into as it prevents you from accidentally changing the rotational rate.

Hope this helps :hello: