How to get a high score

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How to get a high score

UNREAD_POSTby Sascha » Wed Jan 05, 2011 10:00 pm

I've been asked this a couple of times, so here's a comprehensive guide on how the algorithm that grades your landings and computes the numerical score works:

After a successful landing, you can open the landing analysis screen, which will show a lot of information about your performance.

Let's start with what's needed for a perfect landing:

Main gear touchdown
  • Airspeed between 195 and 205 KEAS
  • Vertical speed less or equal to 6 feet per second
  • On centerline max. distance 10 feet
  • Within the nominal touchdown zone 2500 to 2700 feet from the runway threshold (see below)
Nose gear touchdown
  • Airspeed less or equal to 180 KEAS
  • Slapdown pitch rate less or equal to 8 degrees per second
Gear struts weight limits
  • Main gear: max. 220,000 lbs each
  • Nose gear: max. 75,000 lbs

Assuming that no other limit has been exceeded, not meeting one of the above criteria will result in a good landing grade, not meeting two or more will show a safe landing.

If you only slightly exceed limits like the vertical speed at touchdown, the slapdown pitch-rate, etc. your landing will be filed as hard landing in the statistics (the Orbiter might be damaged, but the crew is safe). Anything else (exceeding the ground-speed limit, blowing a tire, missing the runway, exceeding the airspeed or g-force limits during flight, etc.) will be either a crash or a crash landing.

You may touch down anywhere on the runway for a safe or even good landing, but for a perfect landing you'll need to touch down withing the nominal touchdown zone:
Image
(Click for a larger image)

The image shows the location of the touchdown zone (marked by a red rectangle) relative to the runway markings at KSC (left), Edwards (center) and relative to the runway lights on a night approach (right).
Note that at the shuttle landing facility at the KSC the touchdown zone is marked by two large black rectanges. On a night approach, the last set of lights is at the center of the touchdown zone.

OK, now how is the numerical score computed?
All variables (touchdown position, vertical speed, approach precision, etc.) are taken into account. As long as you don't crash, you should get a score.
There's a bonus for safe, good and perfect landings, so typical scores are:
  • less than 100,000 for crash landings
  • less than 200,000 for hard landings
  • about 300,000 for safe landings
  • about 500,000 for good landings
  • about 800,000 for perfect landings
Achieving a perfect landing is very hard and you'll need a lot a practice and patience. Be sure to read the Landing Tutorial and watch the autoland-demo (accessible from the 'menu' on the iPhone version and the help-screen on the iPad version) a few times, the auto-pilot usually performs quite well.
If you wonder how to get scores as high as 900,000 or even 1,000,000 points - I can't tell you about the million (I never broke that mark, but the OpenFeint and GameCenter leaderboards prove that it's possible), but here are a few tips:
  • Try to stay aligned with the runway centerline during final approach (watch the guidance diamond or perform a visual approach) and try to touchdown exactly on the centerline
  • Keep the nose up (the boresight - plus sign in the HUD - about 7 to 10 degrees above the horizon) after main gear touchdown
  • Carefully start to derotate at about 180 KEAS
  • The nose gear should touch down at about 150 KEAS - the drag chute will first open 40% about 1 second after it's been deployed. It will remain at 40% and will start to open fully 5.5 seconds after it's been deployed. Since the drag chute is mounted right below the rudder (and above the vehicles center of gravity) it will cause a positive pitching moment. Try to time the nose-gear touchdown with the fully opening chute, this will cushion the slapdown.
  • Use differential braking to stay on the centerline and decelerate the vehice, but be gentle.

The score is computed at nose-gear touchdown and won't change later, so you don't have to wait until wheels stop to see your landing score.

Happy landings!
Sascha
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Re: How to get a high score

UNREAD_POSTby blackbird1955 » Thu Jan 06, 2011 2:03 pm

Sascha ... man this is beautiful ... without question ... you are the "Shuttle Wizard"!
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Re: How to get a high score

UNREAD_POSTby Tor-DK » Sat Jan 08, 2011 10:42 pm

Thanks for the explanation.

What would be really interesting would be to see how the individual factor is calculated, if possible.
Like how many minus points is given for each pound over lowest possible.
How many points is given for various slap down rates.
And so on.

Or what the theoretical max high score would be if all parameter are the absolutely most perfect possible.
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Re: How to get a high score

UNREAD_POSTby Sascha » Sun Jan 09, 2011 10:39 am

That's difficult to say, because it's non linear. You basically start at zero and get negative points for everything (every inch off the perfect touchdown position, the vertical speed and slapdown pitch rate, etc.). You can't reach the theoretical max because you simply can't land with 0 vertical speed and no weight on the wheels.
The algorithm then uses an exponential function (e ^ negative-score-value) and scales the final value so that the theoretical max would be about 1,150,000 points IIRC. I've chosen this value to make it very, very hard, but not imposiible to break the 1,000,000 points mark.

If you're interested, I could probably post the part of the sourcecode that's responsible for computing the score.
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Re: How to get a high score

UNREAD_POSTby Tor-DK » Mon Jan 10, 2011 4:44 pm

Thanks, but I probably wouldn't understand it anyway. And it's probably better to leave a little mystery behind anyway :D

From looking at a few screenshots of my latest landing statistics it seems to be reasonable to conclude that the most important factor is to be exactly at the centerline. I mean everything has to be perfect already, but for super perfection distance to centerline seems more decisive that e.g. the weight on wheels and vertical speed at touchdown.

My high score has 0 max distance to centerline but (a staggering!) 4 ft/s and 175k lbs at touchdown. Then I have others with a few feet (2-8 feet max from centerline) but with 150k'ish lbs on the mains, and they score 50-100k lower (all other values being virtually equal).
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Re: How to get a high score

UNREAD_POSTby aron123 » Sat Sep 20, 2014 8:34 am

Thanks for share...
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