Smallest Eve Lander - Oscar-B Bonus!

[sevenperforce]

So @Nucleartaxi created a novel challenge: get Jeb to Eve and back, using only Oscar-B fuel tanks!

Of course, given the high part counts when you're trying to build something with the tiniest propellant tanks in the game, only the lander itself needed to be restricted to Oscar-Bs, though there are higher levels for making the transfer stage and/or lifter with Oscar-Bs only.

I decided to just do the transfer stage and the lander with Oscar-Bs. In doing so, I think I inadvertently created one of the smallest fully-stock no-hacks Eve Ascent Vehicles ever...certainly smaller than I've ever seen on the forums:

It's just 13.98 tonnes and it keeps our intrepid Evestronaut safely ensconced in a fairing until he's through the bulk of the atmosphere.

With no further ado, here's the mission!

Ascent and Eve Transfer:

Spoiler

Jeb's heading off by himself for this one. The high part count is due to the massive number of Oscar-B tanks, but the mass is mostly the lifter. It's an SSTO.

Nested fairings are awesome!

Didn't bother with launch clamps.

Respectably high TWR so I started nosing over early, as expected for rocket SSTOs.

The lifter has six Vectors surrounding a single Dart, with an action group to turn off the Vectors once I'm ready to circularize.

Trying to bring prograde down. I used a more lofted trajectory than necessary because I wanted to do the final circularization with my transfer stage, so as to avoid any accusations that I was using my lifter to send me part of the way to Eve.

Vectors turned off, fairing jettison.

First look at the Eve Sample Return vehicle! You can't really see him, but Jeb is nestled in a Mk1 Command Pod right behind the inflatable heat shield.

As expected, I burned out at a high altitude with about 100 m/s of dV remaining, both to ensure disposal of the SSTO lifter and to ensure no one accused me of using the lifter for the transfer.

Staging and transfer engine ignition! From here on out, the entire mission proceeds on a single LV-N (for the Kerbin Departure Stage) and a single Spark for Eve capture, circularization, and return (not counting the ascent vehicle engines, obviously).

Circularized on the LV-N.

Here's another, better look. In the foreground you have the Eve Ascent Vehicle, with three girders for logistics (chutes, ladders, etc.). If you look closely, you can see a single command seat on the lower girder; that's what Jeb will ride down when he lands on Eve. This stack rests on top of an inflatable parachute, which is coupled to a command pod on top of the Spark-powered Eve Stage and the nuclear Kerbin Departure Stage with drop tanks.

Did a long warp to get a good transfer window.

Set up the transfer burn. 1.1 km/s isn't too bad, though I did burn a little more than I expected when I circularized.

Reignited my LV-N for the first apoapse-raising burn! Ignore the ostensible dV requirements. Drop tanks are already half empty; I hated all that empty space, but what's a guy to do? I actually would have gotten more dV for the same tanks if I'd used a Terrier here, but it would have made the stack (and the lift vehicle) far far larger.

Would have been easier if I could have used Mk0 parts.

Second time around, drop tanks jettisoned!

Two apoapse-raising burns complete, we loop around for the Kerbin Departure Burn. This will be the fourth and final burn of the LV-N.

My TWR improved noticeably after I dropped the drop tanks, though it's still nothing to write home about.

Kerbin escape achieved!

Almost bingo on fuel for the LV-N.

Inside Eve's SOI, but not as close as I'd like. Time for some adjustments!

First, dropping the Kerbin Departure Stage...

Lighting up the Spark to start adjustments! The Spark is actually enclosed inside a cylindrical drop tank; I used some clever decoupler placement tricks to make this possible. It shaves off considerable weight rather than using 12 separate radial decouplers. This is the first decent view of the command pod where Jeb will be spending...well, a LONG time.

Closeup from below as I continue to adjust my Eve rendezvous.

Bringing it down...

Further...

That should do it! Warp time.

Eve Arrival and Descent:

Spoiler

Zip forward quite some time, and here we are! I'm coming in with a very high inclination. I'll quickly correct that.

Trouble is, there's no point of reference for correcting inclination.

Setting Duna as the target helped me get it close.

Since I can't risk aerocapture, not without a dedicated heat shield, I'll have to do a full capture burn.

Burn started. Gonna use a bit of physics warp.

Can I burn through in time for capture?

Almost there.

Made it!

I was originally planning to circularize with the Spark, but in order to save dV for the return trip, I'll aerobrake, since I can do it very gently now.

About this time is when I realized that unlike almost every other engine, the Spark doesn't have an alternator. Which means I'm now left running the whole rest of the mission without any electricity. At least the Spark can gimbal, but sheesh!

First cautious aerobraking pass.

And another.

This wasn't getting me very far.

Starting to come through a little more aggressively, which meant sacrificing tail-first approaches and getting some unpleasant heating. Never started to overheat, though.

Gradually bringing the apoapsis down.

Many, many passes later:

Spoiler

This is taking forever.

My drop tanks are starting to get low.

And on I go...

Getting closer!

Making more aggressive passes...tired of how long this took. Remind me to pack solar panels and a heat shield next time.

Now tumbling because I have no attitude control without constant burning of the Spark.

At least we're almost circularized!

This might be about as hot as I'm willing to risk.

Woooooooooooooo!

And here we are in Low Eve Orbit, just where I wanted to be!

Raising my periapse so my return vehicle won't decay.

That should do it!

Time to head for the descent vehicle.

I'm getting good at EVA.

Made it!

Decoupled the return vehicle.

A very slight burn with my Thuds to deorbit.

This will be plenty to ensure a gradual deorbit and a landing on these highlands.

Heat shield inflated. This is where I'm going to regret not having any electricity.

I do, however, have Vernor thrusters and auxiliary Oscar-B tanks mounted on the girders to help a little with attitude control, though they have no roll authority.

Jeb's riding in style!

Vernors thrusting wildly to try and keep the heat shield in the right direction.

Hope I don't burn through all my fuel.

Weeeeeeeeeeeee!

And we're through the worst of it.

Popping the drogues...probably didn't need them, but I'm sure it damped tumbling.

Out come the mains.

Lots of flipping around before the drogues finally open all the way.

Mains open, and stabilized.

Dropping the heat shield.

Used the heat shield to get a good idea about how long descent was going to take, so I could take a break and let it float down. Warping is NOT recommended.

Jeb is excited!

Almost there!

And 3, 2, 1...

0....

And down!

Sample Collection, Ascent, and Return:

Spoiler

Jeb can't wait to get down to the surface.

But first, some housekeeping. Transferring residuals from the Vernor-feed tanks to my strap-ons.

Also, extending ladders so I'll be able to get back into the ship.

And Jeb sets foot on Eve!

First time I've ever landed a Kerbal on Eve, actually.

Gotta plant a flag.

The required sample return.

And the required EVA report.

Time to head back!

Up the ladder.

And yes, I have an external command seat mounted inside the fairing. Fortunately Jeb has no trouble phasing through it.

Ready to head back to Kerbin!

Dropping the logistics girders.

Well, here we are. All ready for ascent in a vehicle that only masses 13.98 tonnes. Will it make orbit? Jeb is sure it will.

Blastoff!

Looking for all the world like Heinlein's baby.

The Thuds lift the stack just high enough that the Dart can manage a TWR of 1.

Speed dropping slightly, mostly due to drag. The Dart just needs to hold out long enough to climb up a bit.

You can see how I timed the capsule approach.

Still climbing on the Dart. The Dart, of course, provides plenty of electricity, so control authority is no longer a problem.

Heating on the Dart and I'm just starting a nose-over.

Blazing hot and bingo on fuel.

Am I high enough that Jeb won't die when I blow the fairing?

Out of fuel. The longer I wait, the greater chance Jeb has of burning up...but the less time I have to make orbit.

All right, here goes!

Fairing away, and Jeb appears inside a cocoon of Oscar-B engines.

The Spark inside ignites, pushing the Dart and its engines away!

Whooooooaaaaaaaa!

Jeb's chair is slightly off-center so the Dart tends to wobble badly.

Setting the ship as my target again!

I timed it so I could burn target-retrograde and not have to worry about the ascent path.

Almost circularized...

Not much longer now...but not much fuel left, either.

And I made it!

Jeb is exultant.

Jeb leaves his ascent vehicle and strikes forth on his own.

Setting up a rendezvous.

Burning carefully. It's tough without a proper heading.

Matching orbits gradually. Don't want to get stranded around Eve without RCS.

This should be a close enough intercept to eyeball.

Closing.

Closer...

Jeb is almost in reach of his ticket home!

No worries now.

Trying to maneuver between these accursed struts.

Made it back onto the ship!

Here's the return vessel.

Warping around for a good transfer window.

Got it!

The burn home is worse than the burn it took to get here.

Thankfully I'm pushing much less mass this time.

Watching the fuel levels in the drop tank.

First apoapse raise.

This will be the one to take me home!

All but bingo on drop tank fuel.

Escape achieved!

Burning off the last residuals.

Drop tank jettison!

Finishing up the transfer burn.

Not the lowest periapsis, but I have plenty of fuel so I'm not concerned. All that aerobraking I did paid off.

Warping home.

Going to lower this periapsis.

Slowly, since I once again have no attitude control and the Spark is wobbly...

Almost there...

Yep, that'll do the trick.

Jeb is thrilled to be this close to home.

Igniting the Spark to help bleed off heat and speed during re-entry.

Full burn now.

Though unconventional, the decoupler DOES help keep drag further back.

Honestly not sure whether the Spark will survive.

Capture success! Now as long as I don't burn up, I'm assured a successful return.

Closest I came to blowing up...

...but I didn't.

Transferring fuel to the lowest tank, just to keep the CoM forward. Don't want to flip or tumble when I hit the lower atmosphere.

Coming down quite close to KSC, really.

Going to drop the heat shield and the transfer stage with it.

Out comes the chute!

Jeb can almost taste the salt air.

Aaaaand....

Splashdown!

That's all, folks!

Not bad for my first mission to Eve.

[Nucleartaxi]

Very impressive @sevenperforce! I'm surprised how you managed to get your lander so light. For mine, I had to add way more boosters and the lander ended up being above 45 tons. Make sure to post this in the challenge thread so everyone can see it!

[NotAgain]

On ‎30‎/‎08‎/‎2017 at 11:05 PM, sevenperforce said:

Am I the only one that sees Tintin's Moon Rocket here?