Challenge So You Think You Can Land?

[dgatsoulis]

It's been a while since my last challenge.
For this one, I wanted to get away from the usual tight-ΔV-planning-type of challenge and post one that requires flying skills.

It's a visit to a moment that must be one of the most memorable experiences for every Orbinaut: The first unpowered runway landing.
For me, that experience is up there with the first ISS docking and the first Brighton Beach landing.

THE CHALLENGE:
You are returning home after an interplanetary mission. All that is left is to perform an unpowered reentry and land on the designated runway next to your base, with which you are pretty much lined up.
Standard stuff for any seasoned Orbinaut, don't you think?

Well... as always, there is a catch. Your home is Olympus base on Mars and the runway is 6 km long, 120 meters wide. It will take some serious flying skill to manage to land on it with the help of only a few kilograms of RCS fuel.

I've included 3 identical scenarios for the 3 popular winged vessels: DeltaGlider - DeltaGliderIV and the XR2 Ravenstar. Pick your favorite ship and try out the challenge.
As usual a lua script accompanies each scenario, checks if the challenge goal has been met and returns you a score.

GOAL:
You have only 10% of RCS fuel at your disposal. Reenter and perform a soft landing on the "Olympus Runway" base, which is next to the default "Olympus" base on Mars. Stop the ship as close as you can to the middle/center of the runway. The score is returned in distance from that point (meters).

FAILURES: (The script checks for these and lists them as failures)
-Bouncing out of the atmosphere and back into space -duh!
-Touching the Martian surface anywhere outside the runway.
-Touching down the spacecraft with a high horizontal ( more than 500 m/s) or vertical ( more than 10 m/s) speed.
-Adding fuel via scenario editor.

HELP/HINTS:
The runway is a base on its own named Olympus Runway. The orientation is 90/270.
The atmosphere is thin and the ships will have very little lift at slow speeds. you'll need to line up with the runway from early on, since any last second maneuvers will be extremely difficult.


NOTES:
The runway base that is added on Mars, will not mess up any enhancements or changes you may have made to the default Olympus base, since the challenge is set on a custom solar system, identical to the default but with its own Martian bases. For a better runway texture, try out the [ame="http://orbithangar.com/searchid.php?ID=5829"]High-Res Martian Runway [/ame] by adam001d (not included)
I've added a nice little surprise in the intro, let me know what you think.


As usual, download the attachment and unzip it in your Orbiter directory, maintaining directory structure. Run the "Mars Runway Landing" scenario, in the Challenges Anthology\(name of ship)\ folder
Please read the Add-on Doc\SoYouThinkYouCanLand.txt for some additional info.

Have fun, safe landings.
:cheers

 

[ADSWNJ]

Hi DG

A couple of questions:

1. How do I remove the green text (goals / restrictions), to prevent it overlapping on the yellow text (RCS fuel, etc)?

2. For the initial entry ... I'm either skipping off or burning up. (I know ... it's part of the challenge!) Can you give me any initial pointers to at least get into a stable atmospheric glide? E.g. do you start inverted, sideways or right side up and at what range of AoA. Hints welcome!

 

[dgatsoulis]

I knew that there would be some trouble with the text, but I couldn't find a way to place it close to the edge of the upper right corner and fit all possible screen resolutions people use. It should work ok for 16:9 formats, but it would be great if you could post a screenshot and your screen resolution.

Since you are burning up, you are using either the DGIV or the XR2, correct? Go for an initial right side up approach with full trim up and then when the vertical speed levels out, start banking and change the trim to stay at an altitude where you don't have too much temp.

I almost never look at the AoA since different ships require different AoA to do the same thing. I find the vertical speed and the vertical acceleration indicators much more useful.

Going inverted or making some high bank S turns to lose some of the initial speed is entirely up to you. My choice was to make an 180° and head for the base from East to West, but you are already lined up to do the West-East approach if you want.

 

[BruceJohnJennerLawso]

Is glideslope MFD considered cheating?

Oh, by the way, for us non-aerodynamic types, would you mind creating a Shuttle-A version of this challenge? I found one of my most memorable experiences in orbiter was a Shuttle-A landing performed under similar conditions on Earth. About 40 tries did it

 

[ADSWNJ]

Is glideslope MFD considered cheating?

LOL. I was having a look at the GS2 screens, trying to figure out why my Delta Azimuth was almost 180º. I need to educate GS2 that when I am more than a half-orbit from base, I cannot turn 180º around and fly back to base, even if it is closer!

Anyone who completes this challenge with GS2 up (latest version) ... please go to CFG, switch on Extended Track Save (XTS) and then save a User Glideslope (SAV + OK). Then PM me the UserSave file. I'd love to see the data!

 

[dgatsoulis]

Is glideslope MFD considered cheating?

Not at all, but you'll have to enter the VASI and PAPI in the runway's config file to make it work properly. I have no idea what values they need to have to guide the spacecrafts to a correct glide path.

I'll record a successful landing and send the playback to Andrew, so he can help with that.

Oh, by the way, for us non-aerodynamic types, would you mind creating a Shuttle-A version of this challenge? I found one of my most memorable experiences in orbiter was a Shuttle-A landing performed under similar conditions on Earth. About 40 tries did it

I can't even remember the last time I flew the Shuttle-A, but I don't see how an unpowered reentry and landing on Mars would be possible.

 

[malisle]

I failed the mission but not by much ,at least not in the cosmological terms Horizontal and vertical speed were low enough to check with LUA but the ships nose wasn't oriented 90/270 and in an attempt to change that in the last possible moment I ended up far away from the runway with broken landing gear (-7.3 m/s).



Can you give some advice on how and when to properly align the ship?
Also, is it OK to use quicksave/statesaver ?

 

[ADSWNJ]

I knew that there would be some trouble with the text, but I couldn't find a way to place it close to the edge of the upper right corner and fit all possible screen resolutions people use. It should work ok for 16:9 formats, but it would be great if you could post a screenshot and your screen resolution.

Have a look at these attachments, from internal and F8 virtual cockpit mode. The green text font needs trimming.

This is in 1900 x 1200 screen mode, on the D3D9 client.

 

[dgatsoulis]

Can you give some advice on how and when to properly align the ship?
Also, is it OK to use quicksave/statesaver ?

Try to have the same lattitude with the runway and an east (or west) heading several kilometers away from it. Finding out how to do it is up to you.

As for using a save, the script doesn't prohibit it, so you can use one if you want. Whatever feels right to you. Perhaps you can use a save when you've managed to line up and practise just the landing. When you've done it, try the whole thing from the start.

Personaly, if I fail a landing, I exit and retry the scenario, but if you want to use a save, it's fine by me.

Have a look at these attachments, from internal and F8 virtual cockpit mode. The green text font needs trimming.

This is in 1900 x 1200 screen mode, on the D3D9 client.

Like I said, it should be ok for 16:9 settings. (1920x1080) But I've only tested it for 1280 x 720 so I don't know for sure.

Here is what to do:
Open the Script\Challenges\(type of ship you fly)\Mars_Runway_Landing\Challenge1.lua file and find these lines:

note = oapi.create_annotation()
note:set_pos (0.837,0.3,0.998,0.5)
note:set_colour ({r=1,g=0.82,b=0})
note:set_size (0.7)

gnote = oapi.create_annotation()
gnote:set_pos (0.837,0.09,0.998,0.5)
gnote:set_colour ({r=0,g=0.82,b=0})
gnote:set_size (0.7)

Change it to this:

note = oapi.create_annotation()
note:set_pos ([COLOR="Red"]0.787[/COLOR],0.3,0.998,0.5)
note:set_colour ({r=1,g=0.82,b=0})
note:set_size (0.7)

gnote = oapi.create_annotation()
gnote:set_pos ([COLOR="red"]0.787[/COLOR],0.09,0.998,0.5)
gnote:set_colour ({r=0,g=0.82,b=0})
gnote:set_size (0.7)

Save and exit.

The text will be placed more to the left, so you won't have the problem I see in the pics. Sorry about that, but I don't know how to place the text in such a way to fit every possible resolution people use on their screens.

 

[ADSWNJ]

Thanks DG - will try now.

 

[johan]

Using the XR2, my initial entry into the atmosphere was inverted, with 50 deg AoA. I had Aerobrake MFD turned on to help me tune the AoA so that I stay on the edge of skipping out of the atmosphere. It seems the appropriate AoA in the XR2 is around 45-47 degrees.

Once I lost most of the velocity, I turned right-side up, and made the mistake of turning on base sync MFD, and somehow misunderstanding what it told me... so that I did at least one 360 degree turn before reaching the base. Because of this silly mistake, I got to the base with much too little energy, so my typical crash is about 20km short of the runway, with 350m/s airspeed and 15 m/s vertical speed... (I saved the scenario about 100km out from the runway)

:shrug:

Good challenge! I will try it again later when it isn't so close to midnight on a Sunday

:tiphat:

 

[ADSWNJ]

Those note:set_pos (0.787 entries did the trick, DG, so thanks for that.

I've crashed my XR-2 more times than reasonable this afternoon, but at least I'm getting closer! The initial aerobrake from 9000 m/s to 6000 m/s is like a giant HAC in the sky, then the S-turns are the most aggressive I've ever flown!

Excellent challenge indeed.

 

[BruceJohnJennerLawso]

Not at all, but you'll have to enter the VASI and PAPI in the runway's config file to make it work properly. I have no idea what values they need to have to guide the spacecrafts to a correct glide path.

I'll record a successful landing and send the playback to Andrew, so he can help with that.



I can't even remember the last time I flew the Shuttle-A, but I don't see how an unpowered reentry and landing on Mars would be possible.

Not completely unpowered, that would definitely not work. I was just thinking it might be interesting to try on low fuel or with a heavy cargo load. Hitting a pad straight out of an interplanetary trajectory is quite a thrill once you get it right.

On the topic of the actual challenges themselves, I gave it about 10 tries or so & didnt get very far. The only mildly succesful combination I found was with the XR2; come in with a closest approach of 24k, aerobrake down to capture, & then skip off the atmosphere to Olympus. The closest I managed was about 4000 km, just making it into daylight. On the second or third skip I ran out of RCS & lost control of the ship while plunging into the martian dirt :facepalm:.

Ive never tried the HAC, but I cant even see how I could keep the ship under control doing them in the martian atmosphere. Does anyone have any tips on how to keep things under control?

One last note: has anyone else found the scenarios somewhat unstable? I get a CTD whenever the DGIV disintegrates on reentry, and Orbiter refuses to shut down normally after any of the scenarios. Good job though, its definitely worthy of the name challenge :thumbup:.

 

[dgatsoulis]

One last note: has anyone else found the scenarios somewhat unstable?

Me!
I tried my best to "stabilize" them for all possible ways this challenge can be met.

I get a CTD whenever the DGIV disintegrates on reentry,

Try to not disintegrate the ship you are flying.

 

[BruceJohnJennerLawso]

Me!
I tried my best to "stabilize" them for all possible ways this challenge can be met.



Try to not disintegrate the ship you are flying.

Well its not my fault the atmosphere wont get out of the way! :lol:

It does add to that feeling of abject failure when the whole simulation crashes with you.

 

[ADSWNJ]

Ive never tried the HAC, but I cant even see how I could keep the ship under control doing them in the martian atmosphere. Does anyone have any tips on how to keep things under control?

I found the Martian atmosphere to be pretty unforgiving. You need to get to around 35km altitude to get any decent thickness to slow the ship down, but at 9000 m/s+ speed, you need to keep it above 30km or you'll burn up. So it's a case of very gentle balancing of VSPD and VACC on the Surface MFD. (Keep the VACC below ±10, and opposite sign to your VSPD.) Hint - you need to be very willing to roll inverted to use the lift of the wing to keep your VSPD negative. There's an XR-2 setting to allow you to use the Attitude Hold to 90º, which is very handy for rolling inverted.

One last note: has anyone else found the scenarios somewhat unstable? I get a CTD whenever the DGIV disintegrates on reentry, and Orbiter refuses to shut down normally after any of the scenarios. Good job though, its definitely worthy of the name challenge :thumbup:.

It's been rock solid for me, on XR-2. The only thing crashing is me, into the atmosphere. :huh:

 

[johan]

Does anyone have any tips on how to keep things under control?

The XR2 flies reasonably well in the lower layers of Martian air, when the airspeed is around 450 m/s or so. When I say "reasonably well", I mean it's somewhat controllable. Higher speed makes it easier, but of course the scenario has the 500m/s limit on touchdown speed.

If you run out of RCS fuel in flight, it may be that you need to do something counterintuitive like pitch down to gain airspeed, just to be able to have good directional control.

The XR2 does not want to fly at 350 m/s, even very close to the surface. I know, because I got so close I crashed :lol:

 

[Screamer7]

This is a tough one.
I had the runway in sight and my speed was 488 m/s.
But my alignment with the runway was way of the mark.:lol:
I must try it again....

 

[ADSWNJ]

OK - I give up! When your Quicksave is:

Mars Runway Landing 0001 0002 0001 0002 0004 0001

I think I have given this a decent shot. I can get to the runway in the XR-2, a hair under 500 m/s, and below -10m/s vertical, with the spaceship as sloppy as hell, but I cannot stop on such a short strip. With keyboard controls, getting it stable under 400 m/s I think is close to impossible, but without that slow a speed and touching down right on the threshold, I doubt you can stop.

Here's a picture of my last attempt, where the commander was picked up in a Martian golf cart:

 

[flytandem]

I used to do a lot of Mars rolling landings so this was right up my alley.

First try I didn't know whether the runway was north or south of the base so I guessed it was on the south side leaving me seeing I was off course in the last 30 seconds of final, but a valiant rolling effort in the last few Km had me aligned but banked and landing right wheel first and ultimately skidding sideways down the runway and slid to 50 meters off the east end. Fail.

Second attempt was good and landed about 3/4 the way up the runway. Success.

For a third attempt I did somewhat of a cheat by just re-flying the last 125 Km of final from a save on attempt #2 and making a playback. Landing was smooth and came to a stop short of mid field.

Attached is a zip of the third flight. If you extract to your orbiter folder it should place the scenario in the scenario/playback folder and the flight data files in the Flights folder. To replay, the scenario will be in the Playback folder and it's called "olympus_runway_flytandem". (but the zip file is called "olympus_landing_flytandem.zip")

I'm better at Orbiter than making zip folders so I hope it works. :tiphat: