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Real Apollo Style Landing?


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I'm not sure if I'm posting this in the right section, if not my apologies in advance.

I wonder if anyone has ever done a proper Apollo style landing?  I know a lot of you guys have made some fantastic models of the vessels used in the Apollo program, and have made excellent landings on the Mun, but in all the videos I've seen of these, the engine was cut off at some stage during the descent.  Some of you have the skill to then use a suicide burn to complete the landing, but there always seems to be a bit of the descent process when the lander is falling down towards the surface with the engine shut down.

In the real Apollo missions, the boys fired up the engine of the descent stage at 50,000 feet, initially for twenty six seconds (I think) at 10% to allow the guidance system to align the thrust with the centre of mass, and then they throttled up and started the landing procedure for real.  They burned the engine all the way down, only shutting it down when the blue contact light came on on the panel.

Have any of you guys ever done this, run the engine all the way from PDI to "Contact Light" (we don't need to worry about the 10% burn)?  I admit I have nowhere near the skill to do it; although my landings are now almost always successful, they can still be a hair raising experience, usually resulting in a large intake of blood pressure medication to get everything back to normal! :D  If you have, or if you know of someone who has, and there might be a video available showing it, I'd very much appreciate if you let me know.

Thanks everyone!  

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Try the "To the Mun Pt 2" tutorial. It has you do exactly that. But the method in that tutorial is both inefficient and inexact for its landing point.

Other players do something similar called a "constant descent rate" landing, that also uses a continuous burn -- and they swear the method competes with suicide burns for efficiency. There's another guy who swears that a "constant time to Ap" landing or ascent produces precisely optimal efficiency, and that also requires a constant burn -- but I can't vouch for that one from a theoretical standpoint.

However, I would argue myself that it's more important to eyeball a flat landing zone and then to land right on it, than it is to either save fuel or play games with your throttle. To land with extra precision requires spending some extra fuel, and falling straight down for a ways, usually unpowered.

 

Edited by bewing
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3 hours ago, The Flying Kerbal said:

Have any of you guys ever done this, run the engine all the way from PDI to "Contact Light" (we don't need to worry about the 10% burn)? 

In Realism Overhaul, I have. It's not that hard -- somewhat similar to a constant-altitude landing, only that you gradually decrease altitude.

That video was made a long time ago when the Mun was much less mountainous than today, which is an important reason why that landing is as smooth as it is. If you try that on today's Mun, you have to chose an altitude much higher than in the video or you'll run into a hillside. Which means that more likely than not, you'll be high above the ground when you finally kill horizontal velocity. At that point, you have to ask yourself: Why keep the engines running even at low throttle when you don't have to?

The Apollo guys had a compelling reason: the regime for the lander engine prescribed long cool-down periods between restarts, shutting it down for a short while simply wasn't an option.

The real Moon, while not as smooth as the Mun in the video, is still much less rugged than today's Mun. It's also much bigger, giving you a longer view to the horizon to spot oncoming crater walls. That's why that kind of landing (smooth descent without ever shutting down) is easier to pull off in in RSS than in stock KSP.

 

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15 hours ago, Laie said:

The Apollo guys had a compelling reason: the regime for the lander engine prescribed long cool-down periods between restarts, shutting it down for a short while simply wasn't an option.

Actually, prior to Apollo 13 (where the LM Descent Engine was used for orbital maneuvering after the SM anomaly), the manufacturer of the LM Descent Engine had never admitted that the engine could be depended on to ignite a second time, despite it using pressurized hypergolics where all you had to do was open the valves to start the engine.  After Apollo 13 (when a restart was actually done after the manufacturer reluctantly admitted there was no known reason a cold engine couldn't be started again, provided tank pressure hadn't decayed), restarting the Descent Engine became an option, but as noted, for a reliable restart the engine had to be cold -- which, in the radiation-only cooling environment of space, required several hours of shutdown time even after a short burn.

One of the advantages we have in KSP over 1960s technology NASA hardware is unlimited restarts, hot or cold, with "forever storable" propellants.  Along with the tiny/dense/closely spaced bodies, this makes it a more playable game, as many who've played through the early years of the space age in RSS/RO will attest.

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16 hours ago, Zeiss Ikon said:

Actually, prior to Apollo 13 (where the LM Descent Engine was used for orbital maneuvering after the SM anomaly), the manufacturer of the LM Descent Engine had never admitted that the engine could be depended on to ignite a second time,

OT Hell, here I come...

Strictly speaking, the mission required two ignitions (one to lower PE, the other to land) about 60 minutes apart. The engine had been run outside it's mission profile as early as Apollo 5 (the first unmanned test in LEO), where some non-engine malfunction led to an early engine shutdown on the first firing.

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On 01/04/2018 at 12:37 AM, Laie said:

In Realism Overhaul, I have. It's not that hard -- somewhat similar to a constant-altitude landing, only that you gradually decrease altitude.

 

That's a really cool video you linked me to.  A little dated now unfortunately, the Mun has been through a heavy bombardment or two since that landing was made, but it was a really good one to watch.

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