Flight Question Align Plane Question

[Ben_C]

Hi All,

I've been using Orbiter for a few days now and am more than happy getting the shuttle off the pad, into orbit and down again...well, usually within 20km or so of KSC...*cough*close enough.

For my last few flights I've been working on an RV with the ISS. I believe I'm launching in a good window when the ISS track is over KSC, ISS in the neighbourhood and the azimuth for launch is 138deg. My RInc is on average 1.5 to 2.5 deg. However, I seem to burning a whole lot of fuel in an effort to change that to 0.0. It seems the velocity (excuse me if thats the wrong term) does not ever exceed 0.003deg/sec (OMS burn on max), I realise the OMS isn't exactly punchy but am I doing something wrong here or is that the best the OMS will push?

I'm using orbit +/- as appropiate at the node as directed by the MFD prompt. I flew my last attempt with a RInc of 2.4deg and RV'd with the ISS but at a closest distance of around 150km.

Thanks in advance,

Ben

 

[Tommy]

Align Planes MFD is useful during the launch and ascent, as well as on-orbit. Before launch, have Align Planes targeted to ISS and try lifting off at about TN - 360.

The RInc will change a lot during the first part of the ascent - just ignore it until you are traveling at least 4.5k m/s. Then you can try using a bit of yaw to "fine tune" the RInc a bit before MECO.

Once on orbit, the OMS are, indeed, rather weak compared to most other vessels in Orbiter. Getting a RInc of less than one degree during the ascent will help a lot.

I'm not sure about this, and am not at home so I can't check, but it seems to me that the OMS engines aren't lined up with the vessels axis - so the autopilots won't orient the vessel quite right. Seems to me there is an indicator on the HUD (about 15 degrees "down") that indicates the thrust vector - manually aligning that indicator to the normal or anti-normal direction (use the "ribbons" on Orbit HUD) may provide better results.

If anyone who flies the shuttle more often finds any errors in my theory, please correct!

 

[Ben_C]

Tommy,

Cheers for the advice. I've just had a practice and managed a RInc of 0.52deg.

Previously when I've tried to use yaw to adjust I've either been too cute with it or too soon, the speed advice of 4.5k m/s works a treat.

 

[agentgonzo]

Or you can use [ame="http://www.orbithangar.com/searchid.php?ID=2802"]LaunchMFD [/ame]with the off-plane correction.