Challenge Martian moons tour

[Max Pain]

I think I am doing sth wrong. This time I managed to get back to Mars but without any fuel left. I did aerobraking around a quarter of the planet but then I srewed up and overshoot the base, without fuel left.

Time isn't a problem, I still had 3h left, but somehow I don't conserve enough fuel (I do Hohmann transfers all the time). I would like to have around 1000 m/s left for the reentry but at the moment this amount of dv doesn't seem possible.

About your problem of loosing too much energy in the atmosphere: When I come from a hyperbolic orbit I usually do first an inverted reentry, then fly in the upper atmosphere (around 40km at Mars) without loosing much energy.

Good luck on your try! :thumbup:

 

[blixel]

I had two more attempts that ended in really stupid failures. The first failure happened as I was closing in on Phobos. I was something like 150-200km out, so I pressed t to warp time forward to get closer to the time to begin the braking burn. Unfortunately when it was time to press r, I accidentally pressed t again and shot myself into the surface of Phobos.

My next flight ended in an equally dumb mistake. I landed on Phobos first (as I always do), then I went over and landed on Deimos. When I leave Deimos, I always have to turn so that I'm facing Deimos straight-on in order to do the deorbit burn for Mars. What I have always done (successfully I might add), is to just use a little bit of hover to push myself up far enough to clear Deimos.

When I attempted the flight this morning, I did what I always do ... I used a little bit of hover to get clear of Deimos ... but I engaged the main engines as soon as Deimos appeared to be below my line of sight. Unfortunately, the difference between the size of the mesh and the actual size of Deimos was sufficiently different enough that I crashed into an invisible chunk of Deimos while doing the retrograde deorbit burn.

I do have state saver running, so I could start back again from the latest save point, but unfortunately the script doesn't have a way to restore the values. So if you start from a save point, it resets the timer and resets the goals, so there's no way to get the satisfaction of having a "Mission Successful" message when it's all said and done.

Grrr... so aggravating to have perfectly good attempts ruined by something so silly.

 

[dgatsoulis]

I know that having to complete a challenge in one go, isn't the best way to write a script.
Unfortunately my programming skills are limited and I couldn't find a way to have the time-counter begin at engine ignition AND be able to pick up the scenario after a save.

I looked into the method you proposed on your May 13th post, but I haven't had any success. I found a way to keep the correct time in a scenario after engine ignition, but I couldn't get the "goals counter" (checks if you landed on any of the moons) to work.

The thing is that once you find the correct sequence of the things that need to be done, the whole challenge takes less than an hour (realtime) to complete.

Good luck on your next try.

 

[blixel]

I know that having to complete a challenge in one go, isn't the best way to write a script.

It's no problem. I feel like a challenge should be completed from start to finish in one go. (Ideally at least.) But it is frustrating when you get a CTD beyond your control, or some other minor circumstance causes a total mission failure.

I looked into the method you proposed on your May 13th post, but I haven't had any success. I found a way to keep the correct time in a scenario after engine ignition, but I couldn't get the "goals counter" (checks if you landed on any of the moons) to work.

Hmm... I wonder if the goals could be saved in the description and then read back in when the scenario is loaded?

The thing is that once you find the correct sequence of the things that need to be done, the whole challenge takes less than an hour (realtime) to complete.

Yeah, that's about how long it has been taking me to get as far as I've been getting.

 

[Max Pain]

I second the possibility to continue the challenge from a quicksave.

This time I almost got the challenge. I found a way to conserve some fuel, so in this aspect it is now certainly doable for me. On the other hand I crashed the deltaglider on the landing approach :facepalm:.



It's really hard to screw up this late in the challenge. I reloaded a savepoint from statesaver and finished the landing just to see if it would have worked out.



I landed 15 km away from Olympus.

 

[blixel]

I landed 15 km away from Olympus.

Nice job. I'm planning to make another run at it here in a bit. I'm determined to get it in one go no matter how long it takes!

---------- Post added 05-19-13 at 03:24 AM ---------- Previous post was 05-18-13 at 09:46 PM ----------

Well, I did it.

I'm definitely happy that I finally completed the whole thing in one go, but otherwise I don't feel real great about it.

The landing was ridiculous.

I touched down with a vertical speed of just over 5 m/s, so no problem there. The main problem was my horizontal speed. Due to the thin atmosphere, I had a forward speed of 686 m/s when the wheels touched the ground.

I tried to get the wheels on the ground just as I got inside the 50km limit, but I was moving so fast that I didn't get the wheels on the ground until I was 16km from Olympus. Also, because of how fast I was moving, I rolled right through the buildings and kept going for another 25km beyond Olympus.

I used all my remaining fuel to slow myself down.

I'm nearly certain I would have rolled beyond 50km from Olympus if I hadn't burned all the remaining fuel for braking purposes. (Which is terribly disappointing because I wanted to use the fuel I had left as a measure of how well I did overall.) Before losing all my momentum, I turned around and headed back to Olympus.

I was 15.54km from the center of landing pad 1 at wheel stop.

I'd love to finesse my landing to improve my score, but I don't think I have it in me to do this one from start to finish over and over.

I have video of the whole thing. (Not that anyone would be interested enough to watch it, but you might want to skip to various key points just to compare results.)

The first video is Olympus -> Phobos -> Deimos. The second video starts out from Deimos and continues all the way to wheel stop on Mars.

SPOILER ALERT: The videos obviously contain spoilers, so don't watch the video unless you've already figured out the challenge.

Video was recorded with Open Broadcaster: Free, open source software for live streaming and recording

 

[Max Pain]

Well, I did it.

Good job Blixel :tiphat:!
I looked through your videos and our approach is more or less the same. Your transfers are more efficient however, which might be my incompetence or because I am using imfd and not transx.

Nevertheless there is a certain technique, which could save you some few 100 m/s, that you didn't employ. So there is still room for improvement.

I'm nearly certain I would have rolled beyond 50km from Olympus if I hadn't burned all the remaining fuel for braking purposes. (Which is terribly disappointing because I wanted to use the fuel I had left as a measure of how well I did overall.) Before losing all my momentum, I turned around and headed back to Olympus.

Unfortunately the wheel brakes are very inefficient if you have high framerates. Therefore I recommend using d3d7 client or turning Vsync on in d3d9. Then you can just use the wheelbrakes and don't have to burn your fuel.

 

[blixel]

Nevertheless there is a certain technique, which could save you some few 100 m/s, that you didn't employ. So there is still room for improvement.

I've been keeping track of my fuel usage at key points during all my attempts. The 5 points of reference have been:

1. Fuel remaining after the burn TO Phobos.
2. Fuel remaining after landing on Phobos.
3. Fuel remaining after the burn TO Deimos.
4. Fuel remaining after landing on Deimos.
5. Fuel remaining after the burn back to Mars.

As it turns out, I used about 100 m/s more than my average on my Olympus to Phobos trip in this flight. This time I waited until I was at apoapsis before doing any correction for the journey over to Phobos. I thought that it might save fuel if I did the burn at apoapsis since I would be traveling slower, but it turns out that it used a lot more fuel than my average. I had been doing the burn when I was halfway between Mars and Phobos.

But even beyond that I'm sure there's room for improvement.

Unfortunately the wheel brakes are very inefficient if you have high framerates. Therefore I recommend using d3d7 client or turning Vsync on in d3d9. Then you can just use the wheelbrakes and don't have to burn your fuel.

Very interesting. That is a very unfortunate "advantage" the D3D7 client has. I refuse to use the inline client though. It makes Orbiter absolutely unplayable on my new system. When I use to play Orbiter at 1600x900 on my old computer, the inline client was doable, but still much more sluggish than the D3D9Client. But once I got my new computer with a native resolution of 1920x1080, I get as few as 8 or 9 frames per second with the inline client. Apparently it has to do with some change that happened between Windows XP and later versions of Windows. Whatever the case, Orbiter is absolutely useless to me if I'm not running D3D9Client.

 

[Max Pain]

I finally found some time for retrying the challenge, last time I was already really close. This time I did it:


:bananadance::banana:

 

[blixel]

I finally found some time for retrying the challenge, last time I was already really close. This time I did it:

Way to go, you even set the record. One of these days I'll have to do this flight 1 more time just so I can land without wasting all my remaining fuel to slow myself down. After you told me about turning Vsync on, I gave that a tr and it made a massive difference. I still wouldn't have been even close to your fuel score, but it would have been significantly better for my own score if I wouldn't have burned through that last 300+ m/s. Based on my averages, the best fuel score I think I can get is about 6800 using my current flight plan.

Once again, congratulations on getting the top score. Beating flytandem is quite an achievement!

---------- Post added at 11:23 PM ---------- Previous post was at 06:04 PM ----------

I had to give this one more try now that I have a set of brakes that actually work. Unfortunately my trip over to Phobos cost me at least 80 m/s more than my average. (I must be taking off at a slightly different time than I was in my earlier attempts.) I was hoping to end the mission with a total dV usage closer to 6800 m/s, but I came in above that by quite a bit. Even so, for scoring purposes, this was a lot better than my first successful attempt simply for the fact that I didn't have to waste all my remaining fuel to stop.

I'll probably do this again, but I'm going to work on a new flight plan before I fly it again.

 

[dgatsoulis]

@Max Pain

Great job! :thumbup:

Impressive score. There is still some room for improvement, but I doubt it's more than 50-100 m/s.

Do you remember how much time you had left?


@blixel

Congratulations! :thumbup:

Looking forward to seeing the next try with the new flight plan.

----------------------------------------------------------------------------------

Scoreboard on post#1 updated. Remember that videos and/or playbacks are always welcome.

 

[blixel]

On the way back to Olympus.

About 5,000km from Olympus.

I took this right before wheel stop since the information on the left side goes away once the wheels stop. 1 hour and 13 minutes remaining.

Beat my previous score by about 200 m/s.

I missed Olympus by over 10km, but I had enough energy to turn around, roll all the way back, and stop on the runway.

 

[Max Pain]

@Max Pain

Great job! :thumbup:

Impressive score. There is still some room for improvement, but I doubt it's more than 50-100 m/s.

Do you remember how much time you had left?

Thx a lot. I can't remember exactly, but I had around 3-4 hours left. My flightplan was pretty tight, there was not much opportunity for sightseeing.

 

[downloaderfan]

Two questions:
Whats the max horizontal velocity with which i can land the ravenstar in this challenge?
Whats the max horizontal velocity with which a realistic ship,gear can land without gear failure?Considering very low vertical velocity,as low as 0.1m/s.

 

[dgatsoulis]

This is more of a navigational challenge. As long as you land and stop within 50 km of Olympus you are ok.

The script itself only checks for vertical speed, which must not exceed 5 m/s at the time of touchdown. (Both for the moons and for Mars).

The landing gear energy absorption limit for the XR2 is 129 kJ (XR flight operations manual, page 25).

For a challenge that is focused on an unpowered reentry and precision landing on Mars for winged vessels, have a look at my So You Think You Can Land? challenge, where you have to land your ship on a 6km runway. Landing speed must not exceed 10 m/s vertical and 500 m/s horizontal. (It will have to be much less than that, if you want to stay inside the runway).


For a realistic ship, it would depend on the energy absorption capability of the landing system.

 

[downloaderfan]

This is more of a navigational challenge. As long as you land and stop within 50 km of Olympus you are ok.

The script itself only checks for vertical speed, which must not exceed 5 m/s at the time of touchdown. (Both for the moons and for Mars).

AWESOME!!!!!!

The landing gear energy absorption limit for the XR2 is 129 kN (XR flight operations manual, page 25).

As my math is pretty weak,what do i make out of this?This may even sound incredibly stupid somehow but Newton ain't even a unit of energy.

For a challenge that is focused on an unpowered reentry and precision landing on Mars for winged vessels, have a look at my So You Think You Can Land? challenge, where you have to land your ship on a 6km runway. Landing speed must not exceed 10 m/s vertical and 500 m/s horizontal. (It will have to be much less than that, if you want to stay inside the runway).

I havent tried it yet but that would be by far the toughest challenge in the XR2,you get ur horizontal velocity too low and u no longer have control over the vertical velocity,and also not too high,moreover align with the runway,sounds almost impossible.

 

[dgatsoulis]

As my math is pretty weak,what do i make out of this?This may even sound incredibly stupid somehow but Newton ain't even a unit of energy.

Not stupid at all. I didn't check my wording.

The manual shows this:

Which I interpreted as kg*m/s² (Newtons). But as you correctly pointed out, Newtons measure force not energy.

For energy you would need Joules, but then the units should be kg*(m/s)² = kg*m²/s² = N*m

It would be great if someone could clarify this.

From experience, I know that it is possible to land the XR2 with a very high horizontal velocity (>1000 m/s), as long as you touchdown with a very low vertical velocity.

I havent tried it yet but that would be by far the toughest challenge in the XR2,you get ur horizontal velocity too low and u no longer have control over the vertical velocity,and also not too high,moreover align with the runway,sounds almost impossible.

Yeah it is a pretty difficult challenge. You need to find a way to line up with the runway from early on and have a very low horizontal speed (almost stall) during the touchdown. Even if you manage to do that, you also need to brake the ship to a halt before the end of the runway.

You will find a couple of videos with successful landings in that thread.

 

[downloaderfan]

From experience, I know that it is possible to land the XR2 with a very high horizontal velocity (>1000 m/s), as long as you touchdown with a very low vertical velocity.

Yeah i know,i just wanted to know if it was realistic,as the XR2 tends to be.

Yeah it is a pretty difficult challenge. You need to find a way to line up with the runway from early on and have a very low horizontal speed (almost stall) during the touchdown. Even if you manage to do that, you also need to brake the ship to a halt before the end of the runway.

You will find a couple of videos with successful landings in that thread.

At this moment,i only found yours(video) with the ravenstar,pretty amazing how u kept your horizontal velocity just enough to not fall too quickly,landed with a horizontal velocity which is just above the velocity below which i've found that the XR2 starts falling,and even with all that,u stopped almost at the end of the runway.

I will surely try that challenge,if i get time today after completing this one.If not,there's always an another day.

---------- Post added at 02:58 PM ---------- Previous post was at 01:33 PM ----------

huh,man,this hurts.

Just after taking off from deimos and completing the de-orbit burn,i did a cross feed from main to rcs and it suddely said,"Mission failure,scenario editor used"

Another problem i noticed was,after i landed on deimos and took off with a velocity of 6m/s,it still said that i didnt land on deimos,so i had to come back and land again.

 

[dgatsoulis]

I can get the problem with the with the Deimos landing, especially if you are running Orbiter on a machine with a very high frame rate. If there is still some small residual velocity, you will have to try and stay on the surface and kill it, until the message changes to "landed".

But I thought I had taken care of the XR2 crossfeed, to not be recognized as a "cheat" from the script. It is supposed to check for total fuel and not just for main tank fuel.

The funny thing is that after 30 downloads, no one else reported such a problem. I am not on an Orbiter PC to verify this now, but I'll be able to check this and see what can be done to solve it, sometime later tonight. If it's a quick fix, I'll post a patch here.

In the mean time, please use the standard DeltaGlider version attached on post #1 of this thread.
It has been tested more extensively and there have been no problems reported.

Sorry for the inconvenience.

 

[downloaderfan]

the XR2 keeps saying wheels down,wheels up again and again until ur TAS becomes exactly 0.00,i dont think orbiter provides more precision than that...do i have to wait for the status to change?

I dont use the standard delta glider,cuz i dont have a joystick and doing a re-entry gets pretty annoying.I,m not able to maintain a specific AOA.