Redundancy is King - A Duna landing (Pic Heavy)

[Concentric]

No testing required.

Having not played for a week or so, I decided yesterday to set out on my first manned interplanetary mission. Having completed the tech tree, I didn't bother to attach science equipment, nor did I test my rocket whatsoever - its parachutes, rocket engines, emergency ion engines, and so on... I did, however, test the ladders - largely because I was unsure if Jeb would be able to get back in by jetpack.

I threw together a new launch vehicle using some of the new parts and saved it as a subassembly, then built a quick lander for Duna - intending to land on parachutes and aerospikes, and fitted it with an LV-N for interplanetary burns - return included. Just in case all that ran out, though, the capsule, its batteries and its solar panels were set to be detachable and given ion engines and a xenon supply.

After the first launch showed that more struts were required, a little fixing occurred and the rocket launched again.

Five of the new integrated engine-tanks, four X200-16s, a Jumbo-64 and two of the new SRBs made up the launch vehicle - it took a little care to ensure that the SRBs burnt out before the LFBs, but that was really just controlling the throttle to put TWR at roughly 1. Finished the circularisation on RCS, as the lander had no RCS thrusters and couldn't use it. This put this into orbit, with roughly a quarter of the remaining launch stage's fuel left:

It was a long wait for a Duna launch window, but timewarping in the tracking station solves many ills of this sort, it seems. The remaining fuel in the launch vehicle was insufficient to get the encounter, so it was fortunate that the LV-N was on an action group to finish it.

Interplanetary cruising

Then it was merely a matter of approaching Duna from the right side and aerobraking repeatedly. This needed a quickload - to be specific, approaching from the right side needed a quickload.

I had Jeb take crew-reports and EVA-reports - though the lack of an antenna was keenly felt at this point - as it meant one less thing to do if I ever decided to return for science. Also got a nice picture of Ike over Duna on one of my passes:

The landing itself was rather straightforward, burning about a third, or possibly half of the fuel supply with the 'spikes trying to ensure a nice chute-assisted landing on the day side of Duna. The ladders and ladder-transfer procedure performed as hoped, and reports and a sample were taken by the new flag, planted to commemorate a first manned interplanetary mission.

Then it was time to launch back into orbit and settle in for a long wait for a return window. The launch was simple and the no longer needed landing tanks (with attached 'spikes and extra solar panels) were dropped on a high suborbital path to reduce the mass that the LV-N would need to push into orbit.

Not sure those were empty, Jeb...

The lander model itself was examined in light of the mission, and has had a few small changes made: the capsule has been modified into a small ion lander for extremely low-g bodies (Ike for instance), RTGs have been added, and it is now possible to undock from the nuclear section and redock the ionic capsule with it later. This new version may even be capable of a Laythe mission. Maybe. No idea in the slightest if it actually is.

Edited April 17, 2014 by Concentric

[Concentric]

Surely, we can do more...

I looked into the "Could this do Laythe?" question - and the answer was "Probably not without further modification," - largely because I couldn't achieve Kerbin orbit with the lander alone. So, it was modification time. Six drop tanks (and later, drogue 'chutes) were added to a copy of the lander and Bill jumped in for some nice, safe testing.

Liftoff was fine, and orbit was achieved with minimal difficulty. There wasn't an abundance of remaining fuel, but the lander should be capable of getting off Laythe without trouble if it can manage an all-parachute landing. It should also have more fuel left in the LV-N's tank.

Then it was time to test the ion-lander capabilities of the capsule, and run a reach check on the parachutes. Our test target? Minmus, as it has similar gravity to Pol and Bop - which would be ideal secondary targets for ion landing if this ever does go on a Laythe mission. Perhaps on another test, I'll try Mun to get an idea of how it'll be for Ike if I return to Duna - its gravity is about halfway between them, isn't it?

Got a nice, low orbit using most of the remaining fuel in the LV-N's tank, then detached. Or rather, decoupled at the docking port I'd used in the connection. Unfortunately, because of how I'd attached the ion engines, they were stubbornly clinging to the tank, and it took a lot of twisting, wrenching and spinning to actually detach from that stage.

The landing went well, and didn't require high throttle, which is a good sign for a prospective Mun landing with this ion lander. When Bill got out, I had him check that he could reach the capsule's parachutes from the ladder (he could, so those could be used and repacked in future missions), and also checked the EVA report. I already had the report for "Space low above Minmus' Midlands", so I made the assumption that I'd already made a Minmus Midlands landing. A second surface sample doesn't hurt, though, so I decided to get one when I planted the flag. To my surprise, it turned out that I hadn't made any such landing! So I took a sample, a crew report and a surface EVA report, planted a flag and lifted off for an uneventful return to Kerbin.

Next I wanted to test the combined landing and ascent on a Kerbin-like body. I already knew that I could do it on Duna, but I wanted to try to land on parachutes alone. So, the new version of the lander was put atop the same lifter as before, planning to detach from the launch stage once orbit was achieved, deorbit itself, land, and take off again to orbit. Bill stepped up once again, confident.

The additional mass of the drop tanks and their 'chutes, along with a few small tweaks - such as an FL-R10 and an octagonal strut to separate the capsule and the docking clamp/decoupler on the LV-N's tank, along with some RCS thrusters and a few Roundifieds in places - posed little to no problem to the launch. More monopropellant was spent on circularising, but there was still about a sixth of the last launch stage's liquid fuel left. The lander was detached, the launch stage deorbited itself and things were going just fine...

Except... The launch stage entered the atmosphere just before I managed to switch back to the lander. And so it became a race to crash the launch stage into the ocean before the lander was deleted by the atmosphere as it entered on its own, higher path. Facing straight down and burning all remaining fuel at full throttle sent the launch stage hurtling into the water just as the lander fell below 68km ASL. I don't know how much longer it would have been before it disappeared, but a swift switch through the tracking station got my control to the lander before that could happen.

Then, everything seemed on track for a nice landing in the sunny grasslands. I learned a little about when to deploy drogue 'chutes, and I was sure I could land safely on parachutes alone. Somehow, the legs glitched into the ground, the 'spikes spiked in a little, and the whole thing began to shudder. They say "any landing you can walk away from" is fine, but the plan to ascend back to orbit was destroyed as one of the aerospike tanks ripped itself free and the lander fell over. I recovered it (and Bill), then later took this image of the debris:

----

After Bill's testing wrapped up (for now), I determined that even if there may not be enough left in the tank for Jeb to get back on his LV-N outside of a good transfer window, the ion system on the capsule should be more than capable of providing that power. It took some fiddling with maneuver nodes, but I managed to get an encounter with Kerbin prepared. My solar periapse would fall between Eve and Moho orbit levels, and I would catch Kerbin on the return up.

The LV-N ran out of fuel a little over half-way through the burn, so I decoupled the capsule from it... and ran smack into an issue I had only fixed in later iterations of the lander - specifically, the ion engines clinging to the tank there. As it was clinging to a stack decoupler rather than a docking clamp, the grip was much tighter, and no amount of twisting seemed able to remove it. So I went to the tracking station...

... and terminated that irritating piece of debris. This ended up losing me my encounter, but I could burn some more with the ions until another appeared. One did, but it was blinking in and out, and generally being difficult to work with, so I set up a maneuver at the ascending node to fix inclination and lower the periapse for aerocapture.

I'll burn that another time.

[Concentric]

Apparently "More 'Chutes" is not the answer.

Another round of testing with Bill before Jeb's final return burn.

Note the additional radial parachutes. Can you see them?

A bad launch, but I managed to recover it and get orbit with perhaps a sixth of the last launch stage's fuel remaining. Then, deorbited with a long burn on the LV-N to ensure a long pass over land.

It wasn't quite right, and I ended up having to adjust midflight with the 'spikes. Then I thought "Perhaps, with these extra 'chutes, I won't need to fire engines to land safely"...

Wrong. But, well, any landing you can walk away from. It was more smashing of bits after a sudden shudder, followed by falling over as a landing leg tore free, just like last time, only with a lower initial impact velocity.

----

Afterwards, Jeb made his ion burn to get the encounter and bring down his periapse. You can't see it in the above picture, but that's almost directly above the south pole.

I soon realised that I had brought the periapse too low to aerobrake into orbit, and this was about to become a direct landing. The angle was sharp enough that Jeb would land on the Antarctic, and shallow enough that he would come down on the night side.

Desperately burning off as much speed as possible with the ion engines, just in case

Got a nice view of Mun on the way down: I think Jeb's been inspired. He will likely take over the testing of the new model - which means a Kerbin landing-ascent followed by an ionic Mun landing and return, should all go to plan. Jeb planted a flag with this resolve, and to mark the landing site of the first interplanetary return mission.

[Concentric]

Is this really still connected to the Duna landing?

Continuing progress this time, with a few problems and mistakes. First, the placement of the droptanks on the lander happens to conflict with the location of the ladders, so the ladders have to be reworked. Additionally, I had hit on a plan to deal with the landing-gear problem: use I-beams as a decent portion of the landing gear so that the 'spikes are kept clear from the ground.

Jeb gets out to test the ladders before launch

The launch went fine, but the fuel left in the last launch stage after getting orbit wasn't great: if the lander gets heavier, it'll want a better lifter. I set the lander to come down in the grasslands, giving a nice, long stretch to aim at (my precision landing in atmosphere is pretty terrible).

Surprisingly, this version of the lander managed to land rather perfectly on 'chutes alone - even the landing gear was kept clear of the ground by the I-beams. Jeb repacked the 'chutes on the pod, and then it was time to try to get back to orbit. Unfortunately, either the I-beams added too much weight, the launch was too poorly piloted or the starting location was too low - the pod only barely managed to clear the atmosphere and couldn't circularise. Now, perhaps on Laythe that'd be good enough... but I'd prefer to have something that can succeed on Kerbin before I send it on a Laythe mission.

Jeb fumes in the pod. Next time, space. Next time.

The next version of the lander reworked the fuel-lines on the droptanks and added a little asparagus: three more tanks (each with an aerospike, a landing gear, a reaction wheel and two radial parachutes) replaced the redundant landing gear. I also added a pair of droptanks to the lifter, to counter its fuel shortage. These also carried some monopropellant and a reaction wheel each to make things easier to control. I tried adding separatrons, but they just smashed the empty droptanks into the central stage. Things were fine once I removed them, and the droptanks emptied and were dropped at about the same time as their attached monopropellant tanks emptied, making them the last radial attachment to the central launch stage to go.

I had to send this up twice when I realised only after a successful landing (without engine softening) that I had forgotten some of the fuel-lines and the asparagus bit wasn't. Both launches achieved orbit with over 200 liquid fuel left in the central launch stage, and both descents touched down on the landing gear and parachutes without engines firing. The landing gear broke (which may have been a contributor to previous problems), but Jeb got out and performed repairs.

After the landing gear was raised and the lander stood on its I-beams, it was ascent time. The droptanks dropped clear, the asparagus functioned as planned, and, though it took using the ion engines and much of the monopropellant for thrust, orbit was achieved.

Then, Jeb was off to the Mun on ion power. Getting there was just a matter of a long burn, and wasn't really any trouble. I didn't complicate it.

I tried to follow some advice I half-remembered from the last time I attempted an ion landing on the Mun: make a very low orbit, then burn retrograde full power when coming over a crater. This probably isn't the advice in the form that I received it, but successful low TWR landings are not something I have any particular experience in. From that sentence you can probably guess where this is going.

Low...

... and a far-too-fast impact. Quickloading was followed by a series of attempts that ended similarly, culminating in asking myself, "Why not go around another orbit and start slowing down earlier?" and subsequently clipping a mountain shortly after periapse, destroying the ion lander (again). Next quickload, I'll raise my orbit slightly and then decide whether or not to keep trying with this ionic-secondary-lander plan.

Still, a successful Kerbin descent-ascent-Munorbit. This version should be entirely capable of a Laythe mission, though it may need a transfer vehicle.

Edited April 25, 2014 by Concentric

[Concentric]

So, apparently, all that tweaking was good for something after all. Who knew?

Simultaneous missions are fun.

Anyway, all this tweaking has been pushing away from the original intent of RedKing: a single-launch complete Duna system mission. So, I sent another, this time with the fully tweaked Duna (not Laythe) lander, the five-engine ion lander-capsule, and 100% more interplanetary mission experience (and infinitely more manned interplanetary experience: from 0 to 1).

It launched the same, finished its circularisation on monopropellant and burned almost all the transfer to Duna using only leftover fuel in the lifter. I'm pretty sure that with a slightly better launch profile and a really good window, RedKing could get to Duna and aerocapture without using the lander's fuel at all.

Lowered periapse using Focus View to ensure it was on the proper side of Duna, then settled in for a multipass aerobrake. The below is from the pass just before the landing pass, I think.

A nice, neat landing using all of the parachutes and a little softening with the aerospikes. I lowered the opening altitude of the larger three parachutes a touch - not that I'm sure I needed to. I did need to run the landing more than once, though. With a three-leg landing gear layout on a tall lander, if you're rotated wrongly when landing on a slope (Duna, for example), then you fall over.

The landing happened to be soft enough that none of the landing gear broke: Bill tested them when he got out to repack the capsule 'chutes, plant a flag and take a confirmation sample.

Then it was time to launch and test the ion-lander on Ike. This version had ten OX-L 1x6 solar panels, four RTGs, five ion engines and 3200 xenon, along with a little over a thousand electrical charge in batteries. First, though, the launch.

'Spikes on, gear up, beginning gravity turn rather early... got the apoapsis to about 95 using the 'spikes, then coasted out of the atmosphere and switched to the LV-N. Bill only dropped the outer tanks when they emptied, as the LV-N had other uses than just returning to Kerbin.

Specifically, taking the ship to Ike orbit and waiting there to redock with the ion lander afterwards.

The above was not the final orbit before landing. I tried it, but it wasn't working. Recalling some advice about ion landings, and modifying my previous faulty recollection: I lowered the orbit (to 10km circular), then burned at the maximum throttle that did not reduce charge stored, and only went full throttle towards the end. I also boosted the landing with the capsule's monopropellant.

Success! Bill managed to be first to get somewhere for once. That's what happens when you continually measure your achievement against Jeb, Bill.

Well, Bill made it down safely, did some science and planted the flag. Next, docking back with the LV-N and burning for home. Well, actually, next was launching back into orbit, but careful throttle discipline and deliberately going for a high suborbital start managed that handily.

Bill and the Ion lander got into a 50km circular orbit and awaited the probe-piloted LV-N's arrival. It was a matter of an orbit or so, so not too long a wait. Docking when one thing has no RCS isn't too difficult: I pointed them at each other and let the probe do the approach and adjustments.

Then, an escape burn. I burned to escape Ike, then timewarped to a good moment to burn the return. While I wasn't looking, Ike came around again, and slingshotted Bill out of Duna's SOI! A lucky break, that - while I'm pretty sure that having an apoapsis below Ike orbit meant that slingshots would always be outward, I hadn't planned for it, and perhaps it could have pulled Bill's periapse into Duna's atmosphere!

I set up a maneuver around the other side of the sun to get an encounter with Kerbin. While Bill drifted towards that, Jeb was running his own mission - the one linked above. Anyway, after Jeb escaped Dres, I timewarped to Bill to burn the maneuver.

There wasn't quite enough left in the LV-N to finish the maneuver, so Bill undocked, turned about and fired up his ion engines again.

That periapse was about two days before Jeb's Kerbin encounter on his return journey, so so long as Bill returned straight to Kerbin or put himself in orbit after the first pass, then everything would be fine.

Direct aerocapture returns from Duna and Dres are somewhat heated.

Bill put out the solar panels to celebrate his return from being the first Kerbal on Ike - and also, the only Kerbal to successfully land on ion engines. He can hold that one over Jeb's head probably for the next year or so.

This will probably be the last launch in this mission thread: RedKing has been proven as a Duna vehicle, and any further launches can only be considered tangentially connected to it.

Edited May 9, 2014 by Concentric