Deorbit targeting

MrFickles

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Hi, I've recently started getting into SSU, real great work you guys have done :thumbup:

By reading through the forum, I found that you could use MECOtool from SSUv2 to get your OMS-1 and OMS-2 burn parameters to get into orbit.

However, there isn't any explanation about how to get deorbit burn parameters, and how to target different landing sites. The STS-107 deorbit scenario isn't particularly helpful either, it doesn't explain how the TiG and dV are obtained.

Any help on getting deorbit burn pads and how to target different landing sites would be greatly appreciated.
 

Urwumpe

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Any help on getting deorbit burn pads and how to target different landing sites would be greatly appreciated.

The calculations are a bit harder to do, since they have to be done in Orbiter. What you can do is using IMFD or similar to calculate the burn and then pause and translate the data into PEG4 or PEG7 targets.
 

boogabooga

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What corrections? Did you figure out the planet rotation? Or get solver to work?
 

STS

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Yes, we did.

On cell C34, Angular offset due to planet´s rotation, entering -15 usually works. Also, the DV needs to be converted to FPS (not a problem) and the distance given by the spreadsheet be corrected to see it properly on Map MFD.

And also, sometimes some small corrections inside orbiter are required. (Burning a little later or a little sooner from the distance given by the sheet).
 

Thorsten

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Funny to see how we run all into the same problems...

My solution for EI location prediction for the FG Shuttle was a numerical extrapolation of the vehicle state vector in 1 sec steps - can surprisingly be done comfortably within a frame these days and allows to use drag corrections in the future.

The rest is then rules of thumb at the moment.

Entry trajectory ranging from the EI based on drag control gives me ~600 miles leeway, using a curved approach gives another 300 miles at least, so accuracy doesn't have to be so high. Entry angle is basically a function of the periapsis after de-orbit burn - if it's >80 km, atmospheric capture is difficult, < 20 km is unpleasant, so a value in the middle works best for a 350 km orbit, shift slightly higher for a 600 km orbit because vertical speeds scale with the amplitude between apoapsis and periapsis.

And that basically works well enough.

So, you know, if you really can't call MCC - rules of thumb will save the day :)
 

Becker

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Thought i'd post in this thread rather than create another. Spent a lot of time brushing up on the shuttle systems (been a long time) and am finally feeling comfortable getting into orbit - OMS2 - and reentry. I used the solver to get me in the ballpark for the burn and managed to get the 'Atlantis on orbit' test scenario back to KSC 15 with plenty of energy for TAEM procedure.

Shuttle Altitude at burn point 345km - burn time 2:45

Now the solver told me to burn for a 311 fps reduction however this led to an overshoot. Tried 350 fps and fell short. 330 fps worked like a charm and held the trajectory during ops 304 right down to TAEM.

Couple of questions.

Did not see any reentry effects is this normal for SSU?

Deployed air data probes on schedule, powered up the HUDs and flight controls but never got any HUD data. I got her down by flying the HAC from the CRT display. Have I missed something?

Procedure I used from OPS 304 (Actions that work in current sim in bold)
Enter OPS 304 PRO (Right Keypad)
* Set Commander ATTITUDE INRTL To LVLH
* Set Pilot ATTITUDE INRTL To LVLH
* Check PITCH & ROLL/YAW Set To AUTO

* Set RAD CONTROLLER - OUT TEMP To NORM
* Set RAD CONTROLLER (LOOP 1 & LOOP 2) To AUTO A
* Set RAD CONTROLLER - BYPASS MODE (1 & 2) To AUTO
* Set MPS/TVC/ISOL/VLV (SYS1, SYS2, SYS3) To OPEN
* Set NH3 BOILER - NH3 CONTROLLER (A & B) To PRI/GPC
* Set AIR DATA PROBE (Left & Right) To DEPLOY HEAT Mach 3
* Set AIR DATA To LEFT
* Set AIR DATA To RIGHT
* Set RADAR ALTIMETERS (1 & 2) To ON
* Set HUD POWER To ON (Commander)
* Set HUD POWER To ON (Pilot)
* Set PITCH & ROLL/YAW To CSS (Commander)
* Check FLT CNTLR POWER To ON

* Set MLS (1/2/3) Switches To ON
* Set MLS Thumbwheel To (111)
* Press LANDING GEAR ARM (Twice)


Current SSU updated with svn checkout, Revision 2418, built with MSV 2010 - Orbiter 2010 P1

All visual effects enabled
parameters
realism - damage unchecked
perturbations - none checked
transparent glass cockpit - unchecked

Thanks for all your efforts absolutely loving SSU.
 
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