Using BaseSyncMFD

[Genesis27]

Thanks guys for your help...I have tried using Basesync...and use it to try to align myself with Cape Canaveral....when I get to about the 3rd or 4th orbit away, I do a antinormal/normal burn when I cross the grey line until the "Dist" line/display gets my distance close to zero.....So I am happy that my final orbit will pass nearly directly over the base....
Now when I click on the DEO button, and get deorbit mode, I input my reentry angel, anticipation, and altitude...now the MFD shows a white line, yellow line and green line....I understand that the white line has something to do with the burn and "BT"...but not sure what....I notice the white line is in front of the green line and is moving away....how does it help, and in what way??...
Also, can anyone tell me when to burn retro...some tutorials say 17.20M (near Australia), but when I do, I always end up landing in the sea well short of the US....also, if I burn directly over Cape Canaveral, surely that would take me well pass my landing site.....sorry to be a pain, but any help will do....thanks

 

[Tommy]

I don't usually use the DEO program when preparing an aerodynamic (winged) reentry. As for when to de-orbit, it depends a bit. What are you flying? If it's the stock DG then Delta Tweak (at OrbitHanger) can help - it corrects the aerodynamics for a more realistic re-entry profile. Initial altitude also matters - the higher you are the earlier you want to de-orbit. 17.20 M from base is appropriate for a return from the ISS or MIR.

Keep in mind that for a winged vessel, how you fly the re-entry makes a huge difference. Glider style craft can travel quite a long ways if you want - you can easily de-orbit opposite the base and make your target. AerobrakeMFD is indispensible when it comes to re-entry planning.

Also, it's not a bad idea to do the base alignment burn (or at least the last 50k or so) the last quarter orbit before landing - after the de-orbit burn. The de-orbit burn will change your velocity, which will change how much regression there is. Also, consider your runway alignments and how you plan to approach (straight in or HAC) and offset your alignment accordingly. For instance, if I'm coming into Canaveral from the southwest, I'll target about 25k south of Canaveral so I cross south of the runway at a good distance for a right turn HAC onto final.

 

[halcyon]

To further clarify:

BaseSyncMFD = tool usually used to determine only on which orbit your closest passage to the target landing site will be (the deorbit function isn't as accurate as the next module mentioned, AeroBrakeMFD)

AeroBrakeMFD = best tool used for precision reentry.

Everyone has their own method to reentry procedures, here's what I use which I'm sure is similar to what most others use:

- open BaseSyncMFD. Configure to 8 orbits, and note which orbit is highlighted in white (closest passage). If the distance is more then 100K I accelerate time and wait until I see a a highlighted distance below 100k (the reason for this being that it's easier and takes less time to make a correction burn using normal or anti-normal orientation and it's also more fuel efficient). Usually, I'll wait until a distance around 50k pops up

- once highlighted orbit is chosen for my deorbit, I accelerate time until the white line representing my ship passes over the yellow line representing the landing site and my chosen highlighted orbit is now at the top of the list

- when my ship is at a 90 degree angle to the landing site (example: yellow landing site is at the top of the circle denoting 12 o'clock, my ship being at 3 o'clock), I'll do a normal or anti-normal burn to decrease the distance at nearest passage to near 0 (next to PIC, + determines a normal burn, - determines an anti-normal burn)

- when my ship is directly opposite the landing site on the other side of the earth, I perform my deorbit burn, burning so my PeA is anywhere between 20k to 40k (this depends on how high my average orbit alt is. @ 350k I'll burn to PeA 40k. @ 150-200k I'll burn to PeA 20k)

- I accelerate time, watching my alt until it reaches about 130k. Since I fly the XR-2 Ravenstar exclusively, this is when I prepare my ship for reentry and enable the attitude autopilot, choosing an AoA hold of 40 degrees. Once my alt drops below 120k (considered the absolute extreme edge of the atmosphere), AeroBrakeMFD can now technically be used to calculate where you will end up based on your AoA. I however, don't change my AoA from 40 degrees until around 80k in altitude, when you start encountering denser atmosphere and the PSI starts increasing.
When I use AeroBrakeMFD, after inputting my target base I press the PRJ key to change the data format, and then hit the PG key to get a map of the earth, showing my current position, my flight path, my ending point, and a top-down view of the base in the black box with a white grid. As you change your AoA, you will either increase or decrease your flight path distance based on your rate of vertical descent. When the green box showing the end of your flight path is directly centered on the middle of the white grid, this tells you you'll end up right on top of the base

- Throughout the reentry from 80k in altitude and lower, I start changing my AoA based on where AeroBrakeMFD tells me I'll end up in relation to my landing site using the top-down white grid map. The key to the reentry is managing your descent rate. Anything over -90 VS m/s and my ship gets too hot and eventually the hull breaches, and I'm dead. By raising or lowering my nose and changing my AoA, I can control my VS to get through the atmosphere without roasting my crew. At times my green landing point on the top down grid will fall short or extend past the base, and this is normal. Once your ship slows down and you get into the thicker parts of the atmosphere, you cool off more and more, and can concentrate on a higher AoA if you'll overshoot the base and need to bleed off speed at a higher rate, or a lower AoA if you're falling short and need to glide a little further

All in all, this takes practice before you'll get confident with your reentries. A good way to practice is to save a scenario right before doing the deorbit burn, and start experimenting with different deorbit PeA altitudes, and practicing your degrees of AoA while managing descent VS and hull temp.
I usually end up around Mach 3 with the base in sight and around 100,000 ft in altitude, having more then enough time and alt to decelerate to subsonic speeds and do my HAC maneuver over the base.

Good luck!

 

[Lanzfeld]

I use a similar technique as Halcyon but I will use BaseSync MFD DEO function. By careful testing I have found it to be very reliable. The key is to input the correct parameters for your ship.

Select DEO after you align with base. Input Angle=1, Anticipation=23 (XR2 Ravenstar), Altitude=80 km (<---DO NOT LET THIS DEFAULT TO 40KM...THAT IS TOO LOW).

Go retro and burn when you hit the correct position (I think it is a TRL if I remember). Do one more quick base align when 90 degrees from base to correct for your new speed and then about 40 to 45 degrees AOA for reentry and use Aerobrake MFD for exact touchdown.

OH! One more thing! For BaseSync MFD DEO to work accurately you should be in a fairly circular orbit.

EDIT: All my landings are unpowered glides.

 

[Hmuda]

I use BSMFD and ABMFD extensively. I simply make a retro burn to make my trajectory land at the target perfectly and so far I'm yet to see any kind of heat warning go off (I saw a yellow warning once, but that was due to the Attitude AP's inablility to cope with TC).

By the time I need to make AOA adjustments to stay on target, my craft is already cooling and the slow nature of these adjustments prevent the temp go above any kind of treshold.

All I need is to start practicing unpowered landings.