Spaceplane Speed Challenge Redux: Minmus Ice Races

[Wanderfound]

Okay; this was one of my more popular challenges last year, so I thought I'd revive it.

The challenge:

1) Build an SSTO spaceplane (winged, HOTOL, at least partially air-breathing, doesn't drop any parts).

2) Fly it to Minmus (no refueling).

3) From a standing start, see how fast you can get moving while in contact with the Minmus iceflats.

4) Bring your ship back to stationary on the surface of the iceflats.

Stock parts only, FAR/NEAR/Stock all allowed. If you're planning on using a mod and you aren't sure if it's allowed, ask. Do it as a pure surface skate or take off, go to orbit and skim the ice at periapsis; whatever tactics you like, so long as you start and finish stationary on the ice and do it all with the fuel load you started with. Post screenshots of yourself stopped on the ice before and after, a screenshot of your maximum speed and a couple of shots proving that you did fly it from KSC to Minmus.

Minmus Ice Racing Championship: Leaderboard

Wanderfound, 503.5m/s

eddiew, 457.9m/s

UnusualAttitude, 300.6m/s

Kuzzter, 207.5m/s

LordFjord, 129m/s

- - - Updated - - -

Demonstration run:

142.1m/s. Can go a lot faster, but this is just a demo run.

Full flight at http://s1378.photobucket.com/user/craigmotbey/Kerbal/Beta/Iceracing/story

Edited March 10, 2015 by Wanderfound

[eddiew]

Interesting... sadly I'm booked solid for two days due to a local beer festival, but might give this a shot How do you feel about part clipping? I've been itching to try a rapier-nuke combo of late...

[Wanderfound]

Interesting... sadly I'm booked solid for two days due to a local beer festival, but might give this a shot How do you feel about part clipping? I've been itching to try a rapier-nuke combo of late...

Clip away; any clipping advantage will be primarily cosmetic, anyway.

[Wanderfound]

A better run:

252m/s.

Full album at http://s1378.photobucket.com/user/craigmotbey/Kerbal/Beta/Iceracing/Take%202/story

[UnusualAttitude]

Will try this one. My no-nuke policy may play in my favour for once...

[UnusualAttitude]

Well, I found the hardest part was spamming the screenshot key to get the precise moment of takeoff! I think the secret is more Vernors/RCS/whatever to keep the ship pushed against the surface. I used my standard long-range light cargo with some extra RCS. Here is my best attempt.

I do use non-performance related mods; ScanSat, TAC Life Support, Remote Tech, hope they're OK.

Do take a look at the albums; my second attempt Did Not End Well...

1st Run: http://imgur.com/a/oiuw4

2nd Run: http://imgur.com/a/WKRb7

That was fun,

UA

[Wanderfound]

Another run:

A good top speed...

That almost ended in disaster...

But was saved by the always-calm(ish) Ferton:

And came back to a safe landing:

Full album at http://s1378.photobucket.com/user/craigmotbey/Kerbal/Beta/Iceracing/Take%203/story

- - - Updated - - -

Well, I found the hardest part was spamming the screenshot key to get the precise moment of takeoff! I think the secret is more Vernors/RCS/whatever to keep the ship pushed against the surface. I used my standard long-range light cargo with some extra RCS. Here is my best attempt.

http://i.imgur.com/yb0znis.png

I do use non-performance related mods; ScanSat, TAC Life Support, Remote Tech, hope they're OK.

Do take a look at the albums; my second attempt Did Not End Well...

1st Run: http://imgur.com/a/oiuw4

2nd Run: http://imgur.com/a/WKRb7

That was fun,

UA

Nice recovery on the second one.

[UnusualAttitude]

OK Wander...

Please inform Team Kerbodyne that Team UnusuAl Industries are sending up the heavy artillery...

...for Science!

[UnusualAttitude]

...And ExTract Heavy has just touched down on the Flats. The UnusuAl Industries Team is checking their craft and waiting for daylight to make their run.

[UnusualAttitude]

Well, you retain the lead Wanderfound. But you won't believe how close it was...

Anyway, ExTract leads the Mk3 Heavyweight category !!! Now I know I can land her on Minmus. I'll have to try Mun some time.

Full report...

http://imgur.com/a/GfxBF

[eddiew]

No record winners here, but a lightweight (12 ton) entry that reached 167.6m/s. At this point the camera zoomed out all the way for $reasons$ and by the time I zoomed back in it had left the ground. Repeatedly

Mistakes were made:

- Wasted weight with a parachute, then didn't have the delta-v to come home anyway because MechJeb lied. Back at Kerbin it was claiming 8km/s, it was actually nearer 2.5.

- Carried far too much oxidiser because I didn't realise that the LF was draining from an internal tank first.

- One ion engine is clearly not enough to anchor this thing onto the ground at higher speeds.

- Gets very squirrelly in the high atmosphere, despite a stable set of numbers at 25km/mach4.

Still, got to start somewhere Flying with FAR. MechJeb used for (theoretically) more accurate delta-v readings, but that turned out to be lies. Kerbal Engineer because... well frankly I could have built with it then removed the mod if I wanted to hide it

Edited March 7, 2015 by eddiew

[Mister Dilsby]

Here's my first attempt! Max photgraphed speed 150 m/s, max observed 160. Ship clearly needs some work... more Vernors to keep the nose down... maybe a way to stop?

Javascript is disabled. View full album

Hilarious fun. Great challenge! We'll be back...

[eddiew]

Lol, I would never have thought of taking SRBs up as the final stage - proper space dragster there xD

[Wanderfound]

The competition is getting close, I'd better build some buffer zone...

361.1m/s.

Full album at http://s1378.photobucket.com/user/craigmotbey/Kerbal/Beta/Iceracing/Take%204/story

[eddiew]

Second shot... either 264 or 283 m/s, depending on whether numbers in the flight results count.

Pretty sure this bird can do better, but thanks to being an idiot and mounting my primary downforce engine on a slant, had to do the run on thrusters Will adjust and have another crack after breakfast.

Think I need to find a better location though because I was close to whacking into the cliffs at the far side. Would it be bad form to go orbital and land back where I started, or do we have to start and stop within the confines of the ice sheet?

[Wanderfound]

Start stationary on an ice sheet; finish stationary on an ice sheet. Within those limits, it's all cool.

There's speed to be had with an orbital skim, but the relatively fast rotation of Minmus makes it difficult to target your periapsis onto an ice sheet from the heavily elliptical orbits that you'd need for serious speed.

For the real performance tip [1], however: remember that it's a speed run, not a drag race. Acceleration is irrelevant: ground handling and fuel supply have a much greater impact.

[1] I hate giving this clue, because the SRB/KR-2L powered ships are so much fun to watch. But top speed and acceleration are largely orthogonal in this situation.

[eddiew]

Well in that case... Updated Shuriken, now with vernors top and bottom, and twice as many of each, bunny hopping its way to 497m/s peak speed on land

Don't think I'll get much more out of this airframe without some less conventional approaches however... running on fumes by the time it lands. My question now is whether I could have gotten it off Kerbin more efficiently than I did...

Mistakes made:

- there are some little Rockomaxes in the cargo bay, but I think the struts they're on wobble when under load and they end up worse than nothing.

- The wingtip wheels are pointless; they just increase the chances of asymmetrical ground contact, which instantly spins the plane despite being wheels.

[Mister Dilsby]

remember that it's a speed run, not a drag race. Acceleration is irrelevant: ground handling and fuel supply have a much greater impact.

Yeah, that became apparent when I hyperedited a few more versions of my dragster up to the flats...

[Wanderfound]

Yeah, that became apparent when I hyperedited a few more versions of my dragster up to the flats...

You're definitely the leader on style points, though.

I may have to send up a Mk2 design; the current one becomes rather hard to control after 300m/s. Somebody has to crack the 500m/s mark...

[eddiew]

Somebody has to crack the 500m/s mark...

I gave it a go But after a few runs of trying to hit it, the flight report was consistently showing 497m/s tops. After careful scrutiny I realised this is the point at which the vernors simply can't anchor the plane to the ground any more and 'centrifugal' force will pull it away from the surface no matter what I do. With such little fuel to spare anyway, I feel like I have to declare the Shuriken airframe has reached its maximum.

It's funny to be orbiting at 1m altitude though. Even the camera kept getting confused and turning sideways

Found myself contemplating a dragster build, i.e. one that visibly slopes downward when the front wheels are in contact with the ground, so that the main engine would contribute a little, but I'm not sure how stable it would be. With the downforce anywhere but at the CoM, I was finding instability creeping in.

[LordFjord]

How on earth do you manage to keep those stable at those speeds?

I did some clumsy attempts - admittedly this wasn't built for the challenge AT ALL, but never managed to reach speeds where I can slow down again.

So yeah, 129m/s for me:

I tried to go faster, but things become unstable and wobbly, sooner or later the craft just wants to take off.

I also tried to turn around after a hop and break with the nukes, but I am not nearly a good enough pilot so I will spare you the messy shots

I ran outta monoprop when I tried to break and had to rely on the wheel brakes to come to a full stop (which eventually happened).

That SSTO also brought a scansat to Minmus on the trip (cause why not), and also another "special" vehicle for the challenge:

Unloading:

Brave Kerbanaout:

This didn't end well as it went to Kerbin escape trajectory. Luckily the Kerbal jumped off the seat, did a break on his face on Minmus surface and got back to the plane with RCS

[eddiew]

Probably shouldn't give away secrets, but a few pointers...

- A wider wheel base is good but not essential. Drag racers are relatively tall for their width, because they don't have to turn; and nor do you.

- Be absolutely 100% sure your wheels are mounted vertically. Make sure to place them with angle snap, the right way round. If the plane can't go dead straight down the runway at KSC with zero control input, it can't do it on the ice either.

- Make sure the downforce is evenly distributed around the wheels. Pushing down too much at the front will give you all sorts of jitters.

- Friction is your enemy; the ice has friction (albeit not a lot). But Wanderfound already said that you only need to start on the ice, end on the ice, and screenshot your best speed while in contact with the ice

[Mister Dilsby]

But Wanderfound already said that you only need to start on the ice, end on the ice, and screenshot your best speed while in contact with the ice

The winner will enter Minmus SOI at solar orbital speed going retrogade to Kerbin, touch the ice with a single wheel for the millisecond it takes to press F1, reverse orbit somewhere in the Jool system and come to rest on the ice ten Kerbal years later.

[eddiew]

The winner will enter Minmus SOI at solar orbital speed going retrogade to Kerbin, touch the ice with a single wheel for the millisecond it takes to press F1, reverse orbit somewhere in the Jool system and come to rest on the ice ten Kerbal years later.

If you can plot that course, the prize is yours

I'm too lazy for that; my focus was on finding the longest possible strip of ice (a diagonal in the greater flats, unsurprisingly) and trying not to hit the hills at the far side of it.

[LordFjord]

I think Kasuha did that with 800something m/s some time ago. Can't find a link right now. Anyway, I'd prefer the start/stop in one go without going orbital.

I'll try a more serious entry later as my attempt was just for fun. Can also post more glorious 'xplosion pics.