Flight Question Landing the Module on the moon's surface?

[richfororbit]

Hi,

As for landing the Module, what is the key to getting that right? I haven't ever succeeded, I did succeed recently taking off in the authentic module only to create the orbit a little too high on one side, and run out of fuel while doing so.

Must it remain with the engine nozzle facing the way the craft is travelling, half fire on a burn, not a retro. To slow down the velocity, and then pitch the craft so that it angles to an eventual hover.

I have tried slight variations of these sort of moves, but the craft runs out of fuel, even a second time around.

 

[Hlynkacg]

Regardless of which module you are using, the key thing is to understand that your pitch controls your rate of descent.

At 90* from vertical all of your thrust is going into cancelling forward velocity, and none into cancelling gravity, as such you will begin to accelerate downwards (fall). To cancel this effect or even accelerate upwards you pitch your space craft towards the horizontal axis so that your engin is pointed at the ground.

Flying a manual Apollo style approach takes a bit of practice but is quite doable. First get into a reasonably circular orbit 50-100 km above the surface. Start your braking burn approx 350 - 400km from your target.

Use the surface MFD to monitor your vertical speed and your speed along the ground, the orginal Apollo guidance computer used a simple "glide slope" calculation, maintaining a -12* angle of descent. In other words your desired descent rate should be approx 0.2 x your velocity (sin (12*) * velocity).

From the starting orbit described above this should bring you to a near hover 1.5 - 3 km above the lunar surface with around 15 - 20% propellant remaining. From there simply pick a spot and land.

 

[Cras]

Use Pursuit MFD's landing autopilot and watch exactly what it does, it does an Apollo style powered descent and landing, one nice long burn from orbit down to the ground. See what it is doing and how it is controlling your spacecraft and why it is doing so. It gives you the numbers for what it is shooting for in terms of pitch, also a countdown timer to estimated touchdown time so you can see fuel flow during the approach.

 

[richfororbit]

I understand about the pitching of 90, that was similar to what I did the first time around, it is essentially a balancing act in itself, by maintaining enough height and slowing down.

My primary problem of having only 8.00 fuel and trying to get the velocity to slow down quickly enough is the failure. I hadn't fired the engine full throttle to get high up quick enough, as I was at 802 velocity, and 10KM above the surface.

 

[Delta glider]

Can you stop saying 802 velocity, and start staying 802 whatever unit of measerment velocity and don't say 8.00 fuel. What does that mean?

 

[Urwumpe]

And what module are you talking about, for Blakes sake?

The Lunar Module? Of AMSO? Or another add-on? Or something completely different?

 

[statickid]

My primary problem of having only 8.00 fuel and trying to get the velocity to slow down quickly enough is the failure. I hadn't fired the engine full throttle to get high up quick enough, as I was at 802 velocity, and 10KM above the surface.

The LEM has more than plenty enough fuel slow down and hover land.

"slow down quickly enough" this, I would say, is your real problem. You can't control how quickly the slow down is... and the fact is with the given parameters, it takes quite a long time to slow down. Like Hlynkacg said, hundreds of kilometers. Exactly how many? Well, if you want to do the landing manually, you'll probably just have to develop a consistent flight plan. Save a scenario with about half an orbit to the landing site with the glide slope already in place. Then try some different engine burn times (failures included) to see what distance parks you in a low hover (1-3km) above the landing site. Fine tune the decent from there. Just remember that doing an entire LEM descent manually is a very procedural operation, not a seat-of-your pants and intuition kind of thing. There isn't enough fuel to make haphazard guesses.

 

[DaveS]

And what module are you talking about, for Blakes sake?

The Lunar Module? Of AMSO? Or another add-on? Or something completely different?

I think he may be referring to this add-on: [ame="http://www.orbithangar.com/searchid.php?ID=232"]Farscape 1[/ame]

 

[Delta glider]

Farscape 1 is nothing to do with the moon. I have not downloaded but it dosn't look like a hoverer.

 

[DaveS]

Farscape 1 is nothing to do with the moon. I have not downloaded but it dosn't look like a hoverer.

I'm just guessing based on that others have referred to it as the "The Module".

 

[Delta glider]

Oh ok, but module most likely refers to the LM as it lands on the Moon.

 

[statickid]

I just assumed it was this inflatable module:

[ame="http://www.orbithangar.com/searchid.php?ID=5523"]http://www.orbithangar.com/searchid.php?ID=5523[/ame]

 

[Delta glider]

And that can land on the moon?

 

[Hlynkacg]

...you'll probably just have to develop a consistent flight plan. Save a scenario with about half an orbit to the landing site with the glide slope already in place.

...Just remember that doing an entire LEM descent manually is a very procedural operation, not a seat-of-your pants and intuition kind of thing. There isn't enough fuel to make haphazard guesses.

You can do it, I've actually gotten pretty good at them, while developing AAPO (yes I'm still working on it).

Starting a t 100 km parking orbit, wait until you are on the opposite side of the moon from your landing site and then burn retrograde until your PeA is around 50 km. This burn should put your Periapsis over the target, you should also perform any plane changes required at this point.

Coast until you're about 400 km out from the target and then start your braking burn. Focus on canceling your forward velocity but keep an eye on your vertical speed and make sure that it doesn't exceed 1/5th your total velocity (this will translate into the 12* descent I described above).

Done correctly you should end up in a near-hover (vel < 150 ms) around 2 km above the surface and reasonably close to your target.

 

[statickid]

Yeah, I've actually never used any auto-pilots with the LEM. I also used to have some system for landing them but I didn't write it down and now I don't remember. :hmm:

Of course one could do some math to formulate a flight plan, but that would be EVEN more procedural! :lol:

 

[richfororbit]

Woah....

I am refering to the 2012 Module, Spider. That is the one I have along with the Constellation Illustrated one.

The fuel is 8.00 in total. By the time the velocity is 600 or what ever the hell, and the craft is at an altitude it fails either way.

All I've been doing since this attempt is just launching the STS, I've done that okay I guess, I keep forgetting to OMS 1 or 2, I guess it doesn't matter, so long as the orbit is intact. Usually on the dark side of the planet.

I don't know about this Module landing business. I was starting to think, perhaps going to the moon using the Trans x MFD, in a MPCV would be a bit easier, hell I think Launching that shuttle that excessive fuel in the ET is bloody easier in comparison to landing, I used to think that STS was a nightware when I hardly touched the scenario for launch. As for landing well, I won't get there just yet.

Sorry about the blabble!

 

[DaveS]

It's called the Lunar Module (LM). You really need to start with the basics. What you have chosen is to start at the highest and hardest level possible, realistic.

I think I'm not alone when I make this suggestion to you: Start with the default and nothing else Delta Glider. Once you have mastered the even the most advanced orbital maneuvers in the DG, then you can move on to crafts that has lower tolerances for mistakes.

The fact that you have made several threads like this one as well as not really understanding the launch profile of the Space Shuttle and that you don't understand the Orbiter GUI tells me that you are a very long way from trying these realistic crafts.

Only with the strongest recommendations can I tell you to read the Orbiter manual and go through each tutorial available here: http://www.orbiter-forum.com/tutorials.php

 

[C3PO]

Only with the strongest recommendations can I tell you to read the Orbiter manual and go through each tutorial available here: http://www.orbiter-forum.com/tutorials.php

It's not rocket science, right? Well this IS!

 

[PhantomCruiser]

Terminology, terminology, terminology.
On another thread you kept referring to the Farscape craft as "Module". That term has multiple connotations.

Another thing you can do to help us help you, is link what add-on you mean when you are referring to one lander or another. There's at least 8 or 9 lunar landers on my "standard" Orbiter installation. Not a one of them works exactly the same as another.

LOLA (MFD) was a tremendous help for me as I was learning how to land manually. Depending on the craft used, I still feel like I'm mixing paint sometimes.

 

[Delta glider]

I watched the AMSO autopilot do the landing and followed it, but DaveS is right, start with the DG and get up to the 2012 module, spider. Dunno what that is anyway? I know what the LM spider is, but 2012?

---------- Post added at 07:24 AM ---------- Previous post was at 07:22 AM ----------

LM as in apollo lunar module.