Challenge So You Think You Can Land?

[ADSWNJ]

Normally, videos or playbacks of the completion of a challenge would be considered as spoilers.
But that isn't the case here. Even if you know exactly what to do, it still takes time to learn how to perform the landing.

No kidding DG! Amazing flying. I had no idea you could keep it in the air like that at 300 m/s on Mars!

I still reckon the commander would need a new set of underwear after that landing though!

 

[dgatsoulis]

No kidding DG! Amazing flying. I had no idea you could keep it in the air like that at 300 m/s on Mars!

I still reckon the commander would need a new set of underwear after that landing though!

If you notice at the end, I can't even type my own name in the high score! :lol:

I used to be pretty good with the XR2, but for more than a year I've been flying mainly the default DG. Good thing I wasn't recording the mic, 'cause the video would be rated M. (Especially at the end, when I saw the end of the runway approaching fast.)

 

[johan]

(Especially at the end, when I saw the end of the runway approaching fast.)

Right... I had my doubts about overrunning all the way up until wheel stop. In fact for a bit there, it looked like you were deliberately weaving to scrub speed... and then it looked like you were aiming at a corner rather than the centerline to gain an extra 2m of runway... Close!

 

[blixel]

The Martian moons tour challenge brought me back to this challenge again. In the Martian moons tour challenge, you have to land within 50km of Olympus in order to succeed. That makes for a pretty generous margin of error as far as completing the challenge goes, but walking 10, 20, 30, or up to 50 kilometers back to base isn't very appealing.

So I wanted to see if I could complete this challenge yet. And the answer is ... not a chance! This challenge is unbelievably difficult. I started from the beginning and then saved when I was 1,000km from Olympus so I could re-try the last leg after my inevitable failure. After several hours of flying and 6 additional failures (started from the save point), I am giving up.

My biggest problem is that I just can't get in front of the runway. Every time I get up to the runway I am coming in at enough of an angle that there is absolutely no chance staying on the runway. In my best attempt, my wheels touched down just 1 or 2 meters before the runway (which was frustrating), but it didn't matter because despite being very straight, I was still at just enough of an angle that I rolled off the side. So even if I hadn't gotten a failure for touching down before the runway, I would have failed anyway for rolling off the side.

---------- Post added at 05:22 PM ---------- Previous post was at 02:37 AM ----------

I got up this morning and almost immediately came back to this challenge. After another dozen attempts:





I lost track of how many tries it took me to get this, but I believe it was more than 20!

Also, I did not complete this from start to finish in 1 go. I resumed from the 1,000km save point several times, then I resumed from about 500km several times, once I finally understood how to get aligned (and stay aligned) with the runway, it then took me another half dozen attempts from a 100km save point to actually touch down near the beginning of the runway without exceeding the horizontal or vertical speed.

This is without a doubt the most insanely difficult thing I've ever done in Orbiter. Aeroslinging Venus was easier than this.

One thing that really helped me with this challenge was when I finally noticed the RATE readout on Surface MFD. Once you have your Norht/South EQU POS where you need it to be, the only way you can keep yourself from drifting is to make sure that you keep your RATE at 0.0000. And it is EXTREMELY sensitive. If you notice your EQU POS goes to 12.744, then you need to bank to the north by an almost imperceptible amount in order to bring the EQU POS back to 12.745. Then if the EQU POS drifts the other direction to 12.746, you need to nudge the vessel to the south by a TINY amount.

And even then ... when you arrive at the runway with an EQU POS of 12.745, you will still be slightly off center! But it will be good enough that you won't have to worry about rolling off the runway at an odd angle.

Hats off to anyone who can complete this challenge repeatedly and without having to resume from a save point.

The only way I would try this again and again would be if the runway were at least 3x wider. (Preferably even more than that.)

An Earth-like runway on Mars just isn't very practical in my humble opinion.

Having said all that, this was an awesome learning experience. At the very least, I think I will be able to land very close to Olympus without using any fuel from now on.

 

[dgatsoulis]

Great job David! :thumbup:

I was hesitant to create the challenge with such a "small" runway, but it is already very large to be "realistic" for Mars.

The problem is not that the runway is small, rather than the spacecrafts are not very suitable for unpowered landings on Mars. A real Mars glider would have a much larger wing-span and a lot more lift at slow speeds.

But... since I had done similar landings with the XR2 and the DG and I knew that flytandem could do it with the DG, I thought "what the heck, let's see who else can land these ships on a runway on Mars".

Having said all that, this was an awesome learning experience. At the very least, I think I will be able to land very close to Olympus without using any fuel from now on.

That was exactly the purpose of this challenge. :thumbup:

 

[blixel]

Great job David! :thumbup:

Thanks. It feels good to have landed on the runway, even though I had to resume from a save point. But now that I have all the details worked out, I will try to do it all in 1 go at some point. It's just kind of demoralizing to spend the first 20 or so minutes doing something that is very easy, to then fail because you touched down at 5.1 m/s, or because you missed the runway by 5 meters. So to do it all in 1 go, you have to start over and spend another 20 minutes doing the boring/easy part.

I was hesitant to create the challenge with such a "small" runway, but it is already very large to be "realistic" for Mars.

The problem is not that the runway is small, rather than the spacecrafts are not very suitable for unpowered landings on Mars. A real Mars glider would have a much larger wing-span and a lot more lift at slow speeds.

Yes, that is basically what I meant. The runway is fine IF you had a Mars-glider of some kind. But since we're using Earth vessels that don't have very large wingspans, then this narrow runway doesn't seem very well suited for routine use.

Makes for 1 heck of a challenge though.

For routine use, I'd want a Mars-glider of some kind (perhaps something like flytandem mentioned in this thread), OR a bigger target.

That was exactly the purpose of this challenge. :thumbup:

It's a great challenge. It definitely taught me things I probably never would have learned otherwise. I'm really enjoying these challenges/exercises lately. Picking a specific goal and establishing clearly defined requirements for achieving that goal gives the user a purpose and a definite sense of achievement once the goal has been completed. Whereas with Orbiter in general, it is more of a Sandbox system (which is awesome), but you don't learn nearly as much when you dock with the ISS starting with a fully fueled Deltaglider.

 

[Max Pain]

After the martian moons challenge this challenge seemed as the next logical step in my Orbiter learning. I have to admit this is a difficult challenge but it didn't take as much time as the martian moons tour. On the other hand I think that is because you can save in this challenge. I could never have done it in one go.


(I used the Deltaglider)

This is a great challenge, like all challenges from dgatsoulis, and it even taught me something new about basic orbiter controls. I never knew there were two wheelbrakes :facepalm:.

 

[BruceJohnJennerLawso]

So I gave this a few more tries today in the Ravenstar, but I'm sorta, almost getting closer & sorta not. I found that the lowest you can lower the periapsis is about 15 km or so; 14 km roasts you instantly once you hit the thicker air at Mach 32 or so.

So then I figured Id try going in a little higher, around 19 km for a high AOA aerocapture and turned on aerobrake MFD. That almost worked, as I got down pretty close to capture velocity before I skipped out of the atmosphere. I also broke both wings & an aileron too before I got spat out. (Ever the optimist, I then opened TransX to see if I could set up another Mars encounter. Sadly 100 m/s is just not enough to work with )

So Im unsure which direction I should push towards in order to beat the challenge. Am I coming in too high at 19 km, or is the sweet spot at around 20 km & higher, doing an inverted reentry style brake where the atmosphere wont shake my ship around so much?

Have I mentioned that this challenge is awesome? :yes:

 

[blixel]

Am I coming in too high at 19 km, or is the sweet spot at around 20 km & higher, doing an inverted reentry style brake where the atmosphere wont shake my ship around so much?

There are at least 3 ways to get captured.

Option 1. Do what dgatsoulis did in his video.

Option 2. Fly all the way around Mars.

The default periapsis is fine where it is. You don't need to change anything. Just warp time ahead until you're at about 200km, then turn on the APU, close the radiator, and roll heads up. As your V/S decreases, you will need to roll inverted to keep yourself from skipping out. Initially you will need to keep your altitude above ~35km, so be sure you have surface controls turned on so you can pitch as needed to keep your V/S under control.

Option 3. This style:

I brought the PeA down to 33km (not sure if that's necessary), then I fast forwarded time until I was at ~200km, turn on APU, close radiator, set AoA AP to -180 bank / 45 AoA, engage AP at around 100km and make adjustments to AoA as needed. Keep your altitude up around 30km and disengage AP as soon as you are captured. Then you have to roll over as needed to keep yourself in the atmosphere. Fly at around 40-42km until you've gone all the way around Mars to Olympus.

Dimitris' method is probably the best though.

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

 

[blixel]

This was my first successful completion of this challenge from start to finish without using a save point.

 

[dgatsoulis]

That was a freaking fantastic landing!!!

My reasoning for this challenge was:

"Spaceflight is 99.99% boring... 0.01% absolute terror!"

I tried to set it up in such a way that reflects that quote.

 

[N_Molson]

Impressive, your aerobraking is fantastic in precision. :thumbup:

 

[Donamy]

Very nice !! I would have rather seen a HAC approach, for safety reasons, but "...any landing....".

 

[thepenguin]

I'll give this one a try tonight. It looks like a good candidate for the XR2.