Flight Question Deorbiting on the Moon for base approach

[Oceanic]

Hi,

i need some advice. back in orbiter 2006 i used the map mfd as a guide to deorbit when approaching a moon base. the map mfd changed in 2010 and does not show the "impact" point anymore.
so how can i find out when and how long i have to fire my engines to have that point somewhere near the targeted base?

in the last attempts i made my trajectory was always a few hundred km short. i still manage to land safely on the pad but i wasted a lot of fuel.

 

[dgatsoulis]

Solution No1(left): Open the Orbiter.cfg file and add the line: MFDMapVersion = 0
You will return to the old MapMFD

Solution No2 (right): Don't have to do anything. MapMFD's (default) Groundtrack mode shows you the point of impact.

 

[Oceanic]

i always immediately changed the map mfd to orbital path after start :facepalm:

 

[statickid]

lol the newer map mfd is LEAGUES ahead of the old one

 

[blixel]

so how can i find out when and how long i have to fire my engines to have that point somewhere near the targeted base?

An alternative to using Map MFD is [ame="http://orbithangar.com/searchid.php?ID=4530"]Burn Time Calculator MFD[/ame]. See this image:

 

[Mandella]

An alternative to using Map MFD is Burn Time Calculator MFD. See this image:

I use that method myself, but keep in mind that you'll end up quite a bit high over the base, and falling straight down. Not very fuel efficient, but it does work for sci-fi craft that have plenty to burn...

 

[Tommy]

I deorbit opposite the base, and burn until I have a PeA of about 1km. Then I estimate what mt velocity will be when I hit PeA, and use that in BurntimeMFD to figure out when to begin braking. Note that once you begin braking, you will need to slowly add hover thrust (or use a descent AP like the XR seies) to control altitude and descent rates.

 

[dgatsoulis]

The way I go about it is first make my LOI burn for a very low circular lunar orbit (2.5 - 3km alt), aligned with the base.
Then I use BTC to calculate the distance at which to make the brake burn using the hover engines. When I'm close, I orient the spacecraft prograde, then level with the horizon and then pitch up to 90°. I add ~2km to the result of the BTC and begin burning the hover engines when I reach that distance from the base. To compensate for the altitude drop I pitch slightly down and watch the vertical speed and vertical acceleration on surfaceMFD. To adjust left/right alignment I bank at the opposite direction.
It takes a bit of practise, but the result is a LOLA-like landing, without the automation and doesn't use as much Δv.

 

[Cras]

An alternative to using Map MFD is Burn Time Calculator MFD. See this image:

Yes yes yes. Burn Time Calc is perfect for a job like this. I use it in my current lunar landing procedure.