E-Rover to Minmus and back.

[RawChicken]

I thought of this challenge a couple days before, but wanted to comlpete it myself before just to make sure it was possible. This is a hard challenge.

The challenge is:

-Get a rover to Minmus using a rocket/spaceplane.

-The rover must ONLY be powered by ION engines.

-Rover Minums

-Take off with the rover using ONLY ion engines.

-Take off must be done HORIZONTALLY in order to complete this challenge.

-Get the Kerbal back to Kerbin alive without docking anywhere.

Rules:

You can use mechjeb, but players that use no mechjeb will recieve a special mention.

You must post screenshots of the rover landing minmus, and the horizontal takeoff, also getting back to Kerbin.

If you used mechjeb, please say so.

Who wins?

The user that completes this challenge with more kerbals onboard.

Leader Board

-8 Kerbals!!!!-

ThePsuedoMonkey with 8 "mechJebbed" kerbals!

-5 Kerbals!!-

Ninety-Three with 5 awesome kerbals

-2 Kerbals-

NetStranger with two canned kerbals!

-1 Kerbal-

Raw Chicken with 1 brave kerbal!

Ninety-Three with 1 kerbal made of rubber!

EDIT: Here are some screens

I used 4 ion engines at 100% thrust.

Rover lifting off. I do not have a better picture showing this.

Leaving Minmus heading to kerbing!

Panorama picture I took showing Mun, Kerbin and Minmus, and the rover

Rover re entry

Edited April 29, 2013 by RawChicken

[Francesco]

good luck achieving a TWR of more than 1 with ion thrusters only.

edit: I've tried it and it's possible, but it's really painful to takeoff without the help of rover wheels.

[RawChicken]

That is part of the challenge, as I said, its a hard challenge... only for those who can take it

[EndlessWaves]

Minmus has gravity of 0.49m/s², you can achieve around about 1m/s² acceleration with an ion engine.

The lowest angle you can sustain your height at is asin(gravity/acceleration), which comes out at a minimum takeoff angle of around 25-30°.

[Holo]

If you hit orbital velocity, you will begin to ascend.

[EndlessWaves]

If you hit orbital velocity, you will begin to ascend.

I suppose it may be possible to use the unpoppable landing gear wheels to accelerate to a sufficient speed to exceed orbital velocity at the surface if they rotate freely enough.

[Ninety-Three]

I've been experimenting with this, and the theory behind achieving orbit at an altitude of 0 is certainly sound. Currently all my rovers have been flying out of control around 80 m/s (I need to make them wider, it seems), but Minmus's massive perfectly flat stretches provide plenty of space to accelerate, and Minmus friction on rover wheels is negligible: in several seconds, at 50 m/s, my speed didn't decrease at all. I'm a little worried about getting a decent TWR. Even on the quarter-of-the-planet flat runway you get from Minmus, you have to have an at least reasonable TWR to avoid running out room on your quest for 242.61 m/s. With an infnitely powerful computer I'm sure it could be done, but without the ability to plaster a thousand OX-STATs on one rover, some care has to be taken.

Alternatively, if you bend your interpretation of the rules, you could get enough Ion power to hover, and then just have one engine push you forward until you eventually hit escape velocity sideways, but that seems like cheating, so I'm going to keep trying for the fair way.

Edited April 21, 2013 by Ninety-Three
Grammar

[Ninety-Three]

Well I've done it! Sort of. I've documented my journey below. It turns out that using a slightly lag-inducing number of OX-STATs gives plenty of TWR, despite my earlier worries.

My rover landed on Minmus. I set it down at about 2 m/s and was surprised to find that stable.

Landing's the tricky part, deploying is just a matter of nudging the SAS controls. Once I got the rover on its wheels, I zoomed out to identify a long stretch of Minmus to drive along, and fired up the Ions.

When you get going fast, your rover starts moving around a bit more than you'd like.

If you were thinking "Oh my, that seems like quite a bit of air your wheels are getting", yes. A bit too much air. About a second after that screenshot, my rover hit the ground a bit sideways, snapped off part of a wing, and threw itself into the air spinning madly. Unfortunately I didn't get any screenshots of the chaos, but when I had more or less stabilized, this is where I was. Still pilotable, though it now drifts slightly left.

So I pointed myself perfectly at the horizon and soldiered on. Hey, my engines have only been providing horizontal thrust, it still counts! Suddenly my camera changes orientation and I go to the map screen to check.

We have an orbit!

We're going to clear those cliffs, right?

Phew. From there I'm headed cleanly away from Minmus. Now it's just the tedious matter of flying a fixed-panel ion plane with a wonky center of gravity.

[Ninety-Three]

Continuing my rather picture-dense accounting of this challenge in a second post.

Flying ion engines is both fast and exciting. Remind me to never, ever make my probes Ion based.

Have you noticed that my plane doesn't have any re-entry mechanisms? I sort of missed the part of the contest where you're supposed to return your Kerbal alive, until I was in my Minmus exit orbit. Oh dear. Still, let's come in for a landing.

Re entry shots are pretty.

Pretty quickly I start spinning out of control at 60 revolutions per minute. The re-entry on my xenon tanks looks pretty though!

The ground's getting awfully close and flooring the A key isn't stopping my spin. I don't think this plane is going to land.

Luckily, I remember the wording of the challenge. Get the Kerbal back to Kerbin. The ship is disposable!

This plan is seeming a bit weak.

OH MY GOD HE BOUNCED.

Ladies and Gentleman: Neilfrid "Made of Rubber" Kerman.

How do I get home?

[RawChicken]

Good screenshots Ninety-Three!

How many ion engines did you use?

Updated OP with mi screenshots.

Edited April 21, 2013 by RawChicken

[Ninety-Three]

Good screenshots Ninety-Three!

How many ion engines did you use?

The rover has twelve engines, and weighs almost exactly ten tons. Theoretically, it also has exactly enough solar panels to power all those engines. I say theoretically because my math says exactly but I was able to run it at full throttle without draining the battery even when panels were only providing 94% power.

Misc lessons learned: On my decently powerful machine, 320 OX-STATs generated a noticeable but manageable amount of lag, and it was pretty much just dropped frames, rather than time dilation.

While I was still in thin atmosphere, I noticed that the SAS was doing a surprisingly good job of keeping me level, and even generating an unwanted amount of lift (luckily I shut it down before overshooting the continent). I imagine that if I hadn't been missing two wings, and had any idea what I was doing when it came to planes, the plane made entirely of control surfaces could have been taken on a glided landing.

I had some pretty severe problems with left-right unstable rovers before switching to the design you see with wheels two wing lengths away from the body. I'm guessing the bouncing I encountered could be helped by putting more distance between the front and back wheels (and maybe evening out the centre of thrust).

Incidentally: How in god's name did you keep that stick of a rover stable? I was having a nailbiting time with my giant slab, I can't imagine doing this with something that snaps off all its solar panels the instant it leans left.

Edited April 21, 2013 by Ninety-Three

[NetStranger]

Finally made it!

The rover uses 8 ion engines, giving it a TWR of about 0.5 on Minmus. So the only possible takeoff is indeed horizontal.

The only non-stock part used is Flight Engineer plugin (doesn't interfere with controls, only displays a bunch of useful numbers)

2 kerbals went there and back again in one piece each

The landing. Mission control instructed to just get it low enough and then somehow it's going to be fine

Oddly enough that worked

It's midday on Minmus, but instead of having their lunch the crew is about to start rolling

This is our runway

A bit bouncy

And we did it! A stable orbit, that mountain was a close call

On our way back home

What's that smell?

Who said upside down is a bad landing?

The whole thing took about 10-15 failed attempts (it's damn hard to control this thing once it's rolling fast)

[RawChicken]

The rover has twelve engines, and weighs almost exactly ten tons. Theoretically, it also has exactly enough solar panels to power all those engines.

Twelve?? How on earth did you feed 12 ion engines with those panels? I needed all those panels in my rover to power up only 4 ions! Is this any kind of kerbal magic?

I had some pretty severe problems with left-right unstable rovers before switching to the design you see with wheels two wing lengths away from the body. I'm guessing the bouncing I encountered could be helped by putting more distance between the front and back wheels (and maybe evening out the centre of thrust).

Yeah I also have this problem, usually with planes during liftoff.

Incidentally: How in god's name did you keep that stick of a rover stable? I was having a nailbiting time with my giant slab, I can't imagine doing this with something that snaps off all its solar panels the instant it leans left.

Actually this was the easiest part of the whole challenge. Once in the flat surface, I just got the rover pointing at the largest section of flat land, hit on SAS and power up the engines.

SAS kept the rover perfectly stable for me, so much that it could even raise the front wheel and have the rover only with back wheels , plus, because of the curvature of Minmus, the nose kept "lifting" and I had to switch off SAS till it touched the ground and power it on again to maintain the horizontal thrust as higher as possible.

ACTUALLY, the rover landed with one back wheel and started to tilt, and broke 2 of the back solar arrays, as you can see in my first picture, at the back of the rover hahahaa

How many tries did you need?

Edited April 22, 2013 by RawChicken

[RawChicken]

Finally made it!

The rover uses 8 ion engines, giving it a TWR of about 0.5 on Minmus. So the only possible takeoff is indeed horizontal.

The only non-stock part used is Flight Engineer plugin (doesn't interfere with controls, only displays a bunch of useful numbers)

2 kerbals went there and back again in one piece each

Yay two kerbals! That gives you the first position!

BTW, landing on minmus with that engine isnt a bit of overkill huh? Hahahaa

This is our runway

A bit bouncy

So you used a mountain flat instead of the plain surface? Nice, my 3 or 4 first attempts where on mountains, but they kept being too bouncy, until my rover made big leaps and land sideways disintegrating in a million pieces...

I even have a picture of a rover jumping out a very big cliff..and landing on its side at 100 m/s after a few seconds of kerbal panic.

Ill post it later. Good for finding that flat surface btw.

The whole thing took about 10-15 failed attempts (it's damn hard to control this thing once it's rolling fast)

Lol, yeah, I had like 7 attempts of failed rovers.. The worst part is heading to Minmus AGAIN!

Thanks for taking the challenge!

[PirateAE]

can moded ions be used? if so i might have a go

[Ninety-Three]

Twelve?? How on earth did you feed 12 ion engines with those panels? I needed all those panels in my rover to power up only 4 ions! Is this any kind of kerbal magic?

20 of those panels feed an ion, and there's 15 per wing. The only magic is how efficient the OX-STAT tiny panels are. And the bloody lag that 300 of them creates.

Once in the flat surface, I just got the rover pointing at the largest section of flat land, hit on SAS and power up the engines.

SAS kept the rover perfectly stable for me, so much that it could even raise the front wheel and have the rover only with back wheels , plus, because of the curvature of Minmus, the nose kept "lifting" and I had to switch off SAS till it touched the ground and power it on again to maintain the horizontal thrust as higher as possible.

I only discovered that technique tonight, during a run of a new rover I'm about to post. God does it make things easy.

How many tries did you need?

Depends how you count. That was my first try with that model of rover, I thought I was sunk when it tilted and crashed, but tried to stabilize for the heck of it. Shocked to find it worked. Using an earlier rover with wheels closer together, and not knowing the SAS trick, I tilted to my death four times before redesigning.

[Ninety-Three]

I thought I was done with this challenge, but a little voice at the back of my head wanted to to do it again without crashing, and seeing someone get a higher score than me spurred me to action. I built it in the plane hanger for the use of plane symmetry, and didn't know how to move that to the rocket hanger, so I had to build a rocket in the spaceplane hanger, using 2d symmetry only. That was a fun challenge.

Check out the rover. Eighteen wings of 15 panels each, powering a whopping fourteen ion engines. The rover assembly probably weighs in around 16 tons. Those are asparagus-staged jumbo engines providing the majority of my thrust, and they prove remarkably effective.

Check out what I put into orbit! I was amazed at how well that worked.

Once I had it in orbit, it was time to bring up the crew. Two ships got within a kilometer and EVAed four more pilots to me. We're off to Minmus.

I'm still amazed that this balances so easily. I tip it down and I'm off.

Around 150 m/s I tilt sideways again. Hopes for a recovery are dashed when my controllable area is reduced to a cockpit with a wing attached. So I try again. This time I put on SAS, just to see if it helps, and start rolling. After a while, something strange happens.

I looked at my front wheels and saw them doing that, sitll under SAS control. Pretty quickly I realized it was perfect: the rover can't start bumping around if it's only on two wheels. As I kept going, the SAS drifted up, so every now and then I'd disable SAS for a moment to let it drift back down. Eventually I figured out why: The curvature of Minmus was making me rotate relative to where I'd been when I set the SAS. Science!

I accidentally let the SAS drift a little too high, maybe ten degrees, and when I tried to let it drift back down, it stayed exactly where it was. Then I slowly took off. Apparently I'd gotten enough speed.

I leveled out, and continued to rise. Orbit any moment now.

For some reason the camera does a perspective-switchy thing when you achieve orbit. Handy indicator.

I clear the hills and it's back to Kerbin.

Somehow I always end up in that area.

Reentry shots are still pretty.

It starts spinning when it gets low. I realize that those parachutes could have been better placed, and start praying that they're not going to tear off when they deploy.

They made it. Corfrod, Neilfrid, Shelwig, Gregsy (not pictured) and Will (not pictured) Kerman have returned, each convinced they were the one piloting the return in their own cockpits.

[NetStranger]

BTW, landing on minmus with that engine isnt a bit of overkill huh? Hahahaa

That's actually the second stage of my super-heavy lifter, normally used to bring large amounts of fuel into orbit. Never used it as an interplanetary stage before, but worked just well

That mountain was indeed very bouncy, the final jumps were about 40 meters high. The funny part is when the rover is falling at about 10m/s, but the surface doesn't get any closer, since it's a downhill, and then all of the sudden it begins to elevate

The trick to keep the rover somewhat steady was to hit F for a moment after every jump, realigning the ASAS with the new surface angle.

[ThePsuedoMonkey]

I finally managed to do this, and it only took eight iterations! (Jeddin was lucky on that one, since I planned on him hitching on the outside ladders to bring him home). I completely underestimated how difficult it would be to keep the darn thing from bouncing around (I probably made about five attempts for each one too) so I ended up using a little Mechjeb after a while. The Minmus lander from version7 was the same as my final one

The Kerbals don't seem to remember me murderating them via a suspiciously similar vehicle, and even put on a show while recharging the batteries!

Total engine count: 16. I can't fit enough Gigantors on there to power them all, and I'm using a laptop so OX-STATs and OX4s are out of the question due to part count. Instead I cram 14 Gigantors around it and slap 40 Z400s (these don't seem to give me much trouble) on the wings, which gives me a duty cycle of about one half; so I can only go full throttle for a little while. Three wheels seem more stable than four, especially when the ASAS would make me faceplant all the time (it must like you guys more, I guess). Anyway after many disastrous and random fine-tuning attempts I find the right path to go on the lakebed (this path was not quite straight). And away we go!

I started burning straight up when I saw those maintains, I've put too much time into this already! When we arrive for our aerobraking run I see a new sight for me: fire!(-ish)

You may have noticed that I only put one parachute on this and it's in an odd location, so you're probably thinking "that's a bold strategy, lets see if it pays off." It didn't. I was expecting to be able to glide around for a long time to bleed off my speed and then using the 'chute after touchdown before braking, but apparently the Kerbals change your CoM. Anywho, after a few dozen quickloads I manage to "land" the plane, but the 'chute flipped it over at the last minute so now the fearless Kerbonauts are trapped... on Kerbin!

I don't much feel like making another attempt so I tried delivering a crane to flip it over, but the Buran Manipulator doesn't work like that so I just ran over the wings a bunch until they broke free from the pods.

8 Kerbonauts: Bob, Jedbert, Jeddin (AKA 'the lucky one'), Judson, Rickbert, Lucan, Thompton, Burnard, and more unused xenon than you can shake a stick at. Mission accomplished! Lets not do that again.

[RawChicken]

Wow awesome entry ThePsuedoMonkey, you go in first place... at least for now..

[Mawl]

after a 4 designs and reducing the crew from 3 to 1 I finally made it!!

after I finally landed with my Mark 4 rover started to power up my ion engines

we have take off!!

remind me to never again have a different orientation for my cabin and my engines... the orbit was tricky

we have kerbal in our sights... and we strangely look like Handsome Jack`s moon base XD

we had a... slight problem reentering the atmosphere of kerbin... no wings but still flying!!

Bob Kerman you are our hero!!

[RawChicken]

Good entry!

remind me to never again have a different orientation for my cabin and my engines... the orbit was tricky

Yeah, I sometimes do "experimental" planes like thet. Flying them is a nightmare , and the SAS goes crazy!