[WIP] North American Rockwell Mars Excursion Module

[TiktaalikDreaming]

The main issue with the current masses are the ascent tanks seem to have ended up with vastly too much juice. 

Also, I'll add a How-to-mission to the OP.

Edited August 7, 2016 by TiktaalikDreaming
removed incorrect table of propellant values

[Zuppermati]

I've almost done an RO config with really accurate masses and fuels. Only the chutes and the deorbit engine left and a modulemanager bug

Edited July 17, 2016 by Zuppermati

[Jasseji]

@TiktaalikDreaming in reference to the drogue chute appearing above the pod in "mid-air", maybe it's the same problem as here:

 

[TiktaalikDreaming]

1 hour ago, Jasseji said:

@TiktaalikDreaming in reference to the drogue chute appearing above the pod in "mid-air", maybe it's the same problem as here:

 

Could be.  It certainly looks like what I'm seeing.  I'll try disabling KJR (Noo!!!!) and adding an unused mesh if that works.

[Jasseji]

Just now, TiktaalikDreaming said:

Could be.  It certainly looks like what I'm seeing.  I'll try disabling KJR (Noo!!!!) and adding an unused mesh if that works.

Lazy day at work so have time browsing forums

[TiktaalikDreaming]

11 hours ago, Jasseji said:

Lazy day at work so have time browsing forums

Removing KJR certainly established this looks like the issue.  Now working on fixing.

Fixed the Drogue silliness.

Now to add @Zuppermati's RO detail.  The uploadiness.  Which I probably won't get to until the weekend.  But progress!  Yay

Edited July 20, 2016 by TiktaalikDreaming
Fixed

[TiktaalikDreaming]

On 7/19/2016 at 10:35 PM, TiktaalikDreaming said:

Fixed the Drogue silliness.

Or not so much.  I've shrunk the drogue silliness to where it doesn't always show.  I'll shrink it some more.

[TiktaalikDreaming]

I have an update imminent.  I'm getting some issues with having resources changed over for the Real-Fuels-but-not-realism-overhaul config of the fuel cell, but most of everything else has tested fine.  So, there should be an update very soon.

Imgur album embedding is currently offline for the forums, so my quick run through will have but one pic.

So, the docking nodes are elabourated on.  There's the one that's been part of the mod for a while, plus (finally) the socket end of the probe/drogue docking node set-up.  Also, I've added a (not quite happy with it's lower edge but releasing anyway) shielded docking node for the ascent module.  In some testing, because the colliders match the probe and drogue (concave cone, that drogue word gets over used), it actually functions a bit like it should.  It won't make docking amazingly easier, but it will cut out some of the annoying in that final connection.

The two truncated aerospikes now actually gimbal instead of just pretending to.  In reality, you'd thrust vector using differential throttling of the nozzles around the spike, but both engines are small enough to just add gimbaling.  Also, I increased the gimbal range on the descent engine as it was insufficient to counter the CoM offset without chutes.

Continuing on the engines, I changed their exhaust effects so it's a series of exhausts around the centre (much like the Nexus mod, just less, um, big), and added Real Plume config.

Now, the pic of the ascent module reminds me I added an antenna to it, although it's not finished.  There's one arm that comes out to the side after the initial extension, the intention being several of those arms.  I thought I'd be able to just copy and rotate in Unity, but alas, twas not to be.  Yes, it's modeled on umbrella arms.

At some stage, the flag decal on the ascent mod has got rotated around and obscures one window.  I'm aware of it, but as it's not like that in either Blender or Unity, I'm unsure how to fix. 

The cargo frame is much updated, and now only rarely tips over when the ramp is extended.  It's still a work in progress though.

Non-Stock configs are greatly expanded.  The main flavours of when things change are now;

Real Fuels but not Realism Overhaul

Realism Overhaul (big thanks to @Zuppermati for his work on this)

Real Plume (independent of the others)

Connected Living Space (often lumped in with realism overhaul, but can live independently)

 

[LordOfMinecraft99]

I am a tad bit confused.

Up there, you say "But no Realism Overhaul."

Then in the list of configs you have done it says "Realism Overhaul."

Which one is it?

[TiktaalikDreaming]

29 minutes ago, LordOfMinecraft99 said:

I am a tad bit confused.

Up there, you say "But no Realism Overhaul."

Then in the list of configs you have done it says "Realism Overhaul."

Which one is it?

Those are the variants of config provided via Module manager.

There's a Realism Overhaul MM config.  But there's also a RealFuels without RO config for those people using real fuels but not RO.

There's also MM config for RealPlume and Connected Living spaces (mostly so the lab decoupler doesn't break access), but as those don't interfere with anything else, there's no special A without B type config.

Edited August 16, 2016 by TiktaalikDreaming
figured out what actual post LoM99 was talking about.

[NSEP]

Looks simulair to my design:

Did not think about the MEM while drawing this though.

[TiktaalikDreaming]

0.10 is available for download from Spacedock.  I uploaded it a couple of days ago, but I wanted to test in a fresh KSP from the download before announcing, and that's taken a bit longer than usual.

The update includes the various fixups I've mentioned here since the last update.  Primarily, new textures (aka, actual textures) for fuel tanks, chutes etc.  Complete remeshing of the chute canopies.  I don't think there's any functional differences in parts this time around, except I shifted the part centre of the Kottabos Memorial MEM Lab Decoupler while rebuilding the mesh.  So it should be less crazy to attach.

 

[Nittany Tiger]

Tested the MEM in RSS/RO today as part of my Ares run, and I noticed a bug where the engines are still firing even at zero throttle.  This happens both with the ascent and descent engines.

On an unrelated note, I haven't landed it on Mars without it crashing into the planet, but that's just my lack of experience.

[TiktaalikDreaming]

9 hours ago, Nittany Tiger said:

Tested the MEM in RSS/RO today as part of my Ares run, and I noticed a bug where the engines are still firing even at zero throttle.  This happens both with the ascent and descent engines.

On an unrelated note, I haven't landed it on Mars without it crashing into the planet, but that's just my lack of experience.

Yeah, I noticed that too.  I need to work more on the RO+RSS config.

[Nittany Tiger]

Yeah, I might end up debugging it if I can.

Also, been trying to land the MEM without the chute and ballute because in Voyage, their MEM didn't use those.  When I try not to use them, I end up making a crater on the surface.  Always try to de-orbit from 150km, and I don't even get re-entry flames on descent.  Just a bit of heating before I turn on the descent engine and hope I don't pancake again.  I'm guessing this thing might not land well without the chute and ballute.

[TiktaalikDreaming]

10 hours ago, Nittany Tiger said:

Yeah, I might end up debugging it if I can.

Also, been trying to land the MEM without the chute and ballute because in Voyage, their MEM didn't use those.  When I try not to use them, I end up making a crater on the surface.  Always try to de-orbit from 150km, and I don't even get re-entry flames on descent.  Just a bit of heating before I turn on the descent engine and hope I don't pancake again.  I'm guessing this thing might not land well without the chute and ballute.

Yeah, been testing just recently in RSS+RO.  Reentry is scary as hell.  You take a LONG time to slow down

The chutes (both drogue and ballute) need RealChute config.  RealChute overwrites the custom values I set making them behave like normal chutes, and that'll result in craters again.  I almost have a working kevlar drogue, but for some reason, even with identical config, I can't get the ballute to work.  Probably a missing bracket or something, cos it manages to stuff up the RealChute UI

For a chute free descent, you could try adding airbrakes.  I've seen some examples of concepts for that for martian descent.  Not too sure how it'd compare to a 30m ballute for slowing down though.  But it should be much more solid.

[Nittany Tiger]

2 minutes ago, TiktaalikDreaming said:

Yeah, been testing just recently in RSS+RO.  Reentry is scary as hell.  You take a LONG time to slow down

The chutes (both drogue and ballute) need RealChute config.  RealChute overwrites the custom values I set making them behave like normal chutes, and that'll result in craters again.  I almost have a working kevlar drogue, but for some reason, even with identical config, I can't get the ballute to work.  Probably a missing bracket or something, cos it manages to stuff up the RealChute UI

For a chute free descent, you could try adding airbrakes.  I've seen some examples of concepts for that for martian descent.  Not too sure how it'd compare to a 30m ballute for slowing down though.  But it should be much more solid.

Yeah.  It takes 30 minutes from a 150km circular orbit to hit the ground, and to even get to re-entry takes a while.  Furthermore, the RCS gets burned up super-fast in both modules.  It's not a big problem in the ascent phase, but it is in the descent phase, meaning I have to be super-conservative with maneuvers.

On descent, I hit at most 1+ g of deceleration, but that happens around 1 minute until impact, and the engine deceleration isn't enough to prevent a hard landing.  The descent stage has I think 1300m/s of delta V not counting atmospheric adjustments, but you have to kill over 3km/s of velocity after de-orbiting with the solid rocket pack to land safe on Mars.  Aerobraking kills maybe 1 - 2 km/s of that before you pancake.  I would think this would make fuel margins super-tight without the ballute and chute if not flat-out impossible for a powered-only landing.  Maybe Baxter's MEM had more descent fuel, or maybe it used a different descent profile.

I do have yet to try descents from higher orbits, or descent orbits that don't have underground (sublithic?) periaerions so I can aerobrake more in the Martian atmosphere before engaging the descent engines.  Maybe I just need to experiment with different starting orbits before I dump the purity of Voyage's aerobrake-assisted powered descent and start using aids like airbrakes, chutes, ballutes, or a mixture of the three.

[birdog357]

On 9/12/2016 at 11:21 PM, Nittany Tiger said:

 Maybe Baxter's MEM had more descent fuel, or maybe it used a different descent profile.

I would think that since the MEM uses the Apollo CM shape and most definitely has an offcenter CM that it should have used a lifting reentry. If I remember the book correctly it almost sounded like that was the case.

[Nittany Tiger]

On 9/25/2016 at 9:16 AM, birdog357 said:

I would think that since the MEM uses the Apollo CM shape and most definitely has an offcenter CM that it should have used a lifting reentry. If I remember the book correctly it almost sounded like that was the case.

I've tried a skip re-entry profile and I do get lift on descent.  Not sure how significant, though.  Funny enough, the CoM of the fully-fueled MEM isn't that far off so it want to descend pretty much ballistically.  I could add dead weight to offset the CoM more, but I'm afraid that if I do that, then the MEM becomes uncontrollable when nearly out of fuel due to the CoM being even more offset then, and even the high gimballing of the descent engine may not compensate.  Furthermore, more dead weight means more fuel to keep the delta V high enough for a safe descent.  I could give it a shot, though.

[stratochief66]

Behaves well for me. Ignore my failed landing attempt, that was my fault. I'll have to experiment with the range of Mars altitudes I can actually land this great craft on. I had good luck putting it down in Hellas yesterday though.

[TiktaalikDreaming]

6 hours ago, stratochief66 said:

Behaves well for me. Ignore my failed landing attempt, that was my fault. I'll have to experiment with the range of Mars altitudes I can actually land this great craft on. I had good luck putting it down in Hellas yesterday though.

If you're landing on Mars, and not Duna, failed landing attempts are fairly standard.  It's brown pants the whole way down.  :-)

[DiscoSlelge]

Very good mod ! I'm in love with it, I just noticed something weird with the SAS while chute is open if I let the SAS ON and sticking to prograde and then cute the chute fire off the ascent engine en put my SAS on stabilis node, the pod strangly go in another direction totaly incontrolable, have you an idea what my cause that ?

[TiktaalikDreaming]

2 hours ago, DiscoSlelge said:

Very good mod ! I'm in love with it, I just noticed something weird with the SAS while chute is open if I let the SAS ON and sticking to prograde and then cute the chute fire off the ascent engine en put my SAS on stabilis node, the pod strangly go in another direction totaly incontrolable, have you an idea what my cause that ?

Probably a strange collection of how KSP works.

When you trigger a chute in KSP, it plays the deploy animation.  In this case, it should animate the cutes going directly up.  But then, without transition, the chute vector will flip to match where they would be dragged to, by air resistance.  EG: If you're coming in nose forward, the chutes will fire forward, but then immediately snap around to being behind the craft.  If at any stage your velocity drops to nearly zero (I'm not sure what the threshold is, maybe 1m/s) then SAS will diasable anything velocity dependent (eg, retrograde or prograde) switching to stability instead.  That's not the chutes.

And just to clarify, unless you have RealChutes installed, these are just new parachute models using KSP's parachute code.  Apart from how much drag they create, and things like that, they should behave exactly as KSP chutes.

[TiktaalikDreaming]

@Nittany Tiger has been continuing his forays into heavily planned and researched missions to Mars, and mentioned it'd be nice to multistage the solid de-orbit engines.  I have no idea why I didn't think of that before.

Anyway, so far, just as a patch file, here's the de-orbit engines, deconstructed.  This will increase part counts if you're stumbling into issues with that, so I won't be removing the old one.  But next mod update will include the single de-orbit cluster, plus this, frame and individually placeable SRB units.  As separate parts, they're individually stageable.  There's a bunch of arrangements that are symmetrical for 1, 2, 3, 4, 5, 6 or 7 (all of them) SRBs.  So, you can fine(well, finer than before) tune your de-orbit burn.

https://www.dropbox.com/s/sizxnuhz9svjekv/MEM-DeOrbitSplit.zip?dl=0

Arrangements;

Album a/7KPZJ will appear when post is submitted

[TheSutphin]

Hello, I downloaded this for RSS/RO but the RCS on both the descent and ascent stages aren't working. Also, my ascent stage does not stay straight, at all. And I know I have the fuel draining symetrically around the CoM, so I really don't know what the deal is. Anyone got a clue?