New problem! Landing at KSC... I'm a noob...

[unknown.exe]

Ok now I have gotten down the landing at Brighton Beach... I need to land at KSC. I am using the scenario in the
checklist folder. I always seem to fall short of the base and if I dont then I overshoot... I try to extend the time before
I meet terra firma but then I overshoot! Help plerse.

[Pirx]

unknown.exe wrote:
...the scenario in the checklist folder...

Now, where was this crystal ball of mine
Oh, now I see it clearly. You mean "Mission 3 - Deorbit" and you are flying the stock DeltaGlider. Seriously, try providing more information when you ask a question.

The easiest way to arrive at KSC with the right speed is to use constant deceleration. At least it is easiest if you fly manually and do not want to use any fancy MFDs.

Suppose you start experiencing significant drag at D=4,000,000 m from the base and your airspeed is Va=7,250 m/s. You want to arrive at the base with some speed reserve, say Vb=400 m/s. Then you can determine the required deceleration from

a = (Va^2 - Vb^2) / (2 * D) = 6.55 m/s^2

So just control your vertical speed to keep the acceleration shown on Surface MFD near -6.55. If your rate of deceleration is higher, bank less to reduce vertical speed, if it is lower, bank more.

It will help if you create a table for the expected speed at different distances from the base using the formula

Vi = Sqrt(Va^2 - 2 * a * (D - Di))

where Di is the distance (in meters, multiply by 1000 for kilometers) and Vi should be your speed at that distance. For the numbers above, you should get

Code: [Select]

Di, km  Vi m/s
 4000    7250
 3500    6783
 3000    6282
 2500    5737
 2000    5134
 1500    4451
 1000    3642
  500    2590
  250    1853
  125    1341
    0     400
check your speed at each distance and apply more/less deceleration if your actual speed is above/below the calculated one. At the final stage use the airbrake to control your speed as you are turning towards the runway and aligning with it.



Post Edited ( 04-14-08 08:07 )

[GXE3]

Thanks for the new formula Pirx. Printing out now.

[unknown.exe]

Erm thnx

[unknown.exe]

Well now the new problem is that my elevators fall off!!! Then I am screwed... what gives?

[sunshine135]

For the non-scientists out there I recommend Aerobrake MFD. Gets me to the Cape every time.

[unknown.exe]

Thanks again!

[Pirx]

GXE3 wrote:
Thanks for the new formula Pirx. Printing out now.

In case you wonder where it comes from, it is quite easy to derive it:

Change of kinetic energy = force multiplied by distance

m * Va^2 / 2 - m * Vi^2 / 2 = F * (D - Di)

Now if we remember that F = m * a  and multiply both sides by (2 / m)

Va^2 - Vi^2 = 2 * a * (D - Di)

After we solve it for Vi we get the formula from my previous post.

sunshine135 wrote:
For the non-scientists out there I recommend Aerobrake MFD. Gets me to the Cape every time.

I would gladly recommend Aerobrake MFD for almost any ship, though I have some concerns about the standard DG.
As you have to bank heavily, the projected trajectory goes way to the left and right of the base and it may be difficult
to judge whether you are overshooting the base or coming short of it. Something simpler, like Reentry MFD might be a
better choice. I might be wrong, though. The first thing I noticed when I started Orbiter for the first time was there
was no sound, then Goolge brought me to Dan's site and I also downloaded DGIV. So I have almost no experience
with the stock DG.


A note to unknown.exe: If you want to experience a more realistic reentry, or at least one that looks more like Space
Shuttle, download DeltaGlider IV from Dan's site or DeltaGlider-XR1 from http://www.dougsorbiterpage.com/. With
these ships I can wholeheartedly recommend Aerobrake MFD.

[ar81]

For reentry and landing I use Aerobrake MFD and BaseSync MFD.
Once you master them, you can land with a DGIV without using engines during the final approach.