V 0.90 smallest SSTO challenge

[Ferdoni]

Hi fellow Kerbals!!

So i've been checking out some SSTO rocket designs on the Kerbal forum. But I miss something, all challenges and designs for a mini SSTO rocket are for older versions of KSP like the monopropellant and ion minirockets wich could go to Mun and back. But because the new version I want to challenge everyone to build the smallest SSTO. I'm just very curious wich other designs you guys have got.

And by smallest I mean measured by weight. (Part count doesnt matter)

5 rules:

- challenge is only for the 0.90 version

- no mods (and cheats)

- it has to orbit Kerbin

- weight has to be in three decimals precisely

- total weight has to include the given weight of 'massless' parts (shown in the VAB or SPH)

My smallest design is 2.1-something tons, I will post evidence (pics) of that later on.

No points or something, the smallest design wins.

Edited April 21, 2015 by Ferdoni
updating rules

[Rfmeijboom]

Do you measure the weight as shown in the VAB or in the vessel info in the map view?

These values can differ depending on the physicsless part used.

Edit:

And also, should the rocket be manned?

And if so, are command seats allowed?

[Ferdoni]

I don't know if there is a lot of difference in those values in v 0.90. But i suggest that you have to show both weight values and the heaviest one counts.

Edit:

No further rules so if you want to, you could add them, but they are pretty heavy and in comparrison to the unmanned pods a very bad choice.

[Mister Dilsby]

Why not crewed?

2,046 kg on the runway, turbojet+RCS, SSTO with propellant to spare.

Keys to the design:

--two ROUND-8 with oxidant drained and the monopropellant tank between them, for stiffness.

--Oscar-B tank in front to mount the seat (no oxidant)

--OM-10 massless RCS thrusters for circularization

--wing strakes are the best lift/weight ratio in 0.90.

--no control surfaces, just a small inline gyro and battery

I could make it quite a bit lighter by taking the seat off and reducing fuel appropriately, but kerbals like to fly

[Ferdoni]

2,046 kg on the runway, turbojet+RCS, SSTO with propellant to spare.

Well sir, you've proved me wrong, very good design

[Rfmeijboom]

5 Parts, less than 1,3t with fuel and battery power to spare.

If you replace the probe with a command seat you could do it manned just as easy.

Edit:

You could also remove both batteries and do it on a single small battery or solar panel. But I like the look of the batteries.

exact mass should be: 1,295 if you count all the parts including the batteries (they are massless, so are not added in the info on the map view.

Edited April 20, 2015 by Rfmeijboom

[BoobyTrapGaming]

how do you see all three decimals? i can only see one...

[Rfmeijboom]

In the vessel information in the map view you get 2 decimals, however the massless parts are not included. So the mass can be slightly lower than the mass in the VAB/SPH.

To get more decimals you can use mods like kerbal engineer, or just add the individual part masses together like I did.

[Streetwind]

I knew it would end up as something like Rfmeijboom's concept. Spaceplanes might be able to land again, but pound for pound, wings just can't compete with the simple tank + engine combo of rockets. Especially with the 48-7S so deliciously broken.

But I thought: If his rocket had fuel to spare, then why use a FL-T200, if a FL-T100 does the job just as well?

Okay, I lied. There's a Round-8 in there too. Because what better way to celebrate its recent new lease on life?

It definitely did help make it into orbit! Apoapsis actually went quite bit higher than I expected, as you can see from the orbit shape and velocity. I just burned until it was dry, probably had around 100 dV spare.

Mass on the pad: 0.83t.

This is a 100% stock instance, so no KER views or anything.

Edited April 20, 2015 by Streetwind

[Mad Rocket Scientist]

[..]

- no mods (and cheats)

[..]

Infiniglider breaks this rule, right?

[Foxster]

0.770t...

You can shave some off down to 0.674t by taking a bit less fuel but getting orbit is harder as the dV is 4686, which is enough but not every time, unless you are a better pilot than me. With both tanks full I can make orbit every time.

Edited April 20, 2015 by Foxster

[Ferdoni]

Infiniglider breaks this rule, right?

Yes, it's a doubtful use of the game so I rather see it as a cheat

[Rfmeijboom]

Nice Streetwind,

I knew I could get the mass down by losing some fuel, but I didn't think it would go down this far.

Nicely done.

@Foxster,

Nice design, but half your craft is 'massless' parts.

If you add the VAB part masses together it's like 1,56t or something in that range (added the masses in my head from memory).

[Foxster]

@Foxster,

Nice design, but half your craft is 'massless' parts.

If you add the VAB part masses together it's like 1,56t or something in that range (added the masses in my head from memory).

There's nothing in the rules about that.

[Ferdoni]

I don't know if there is a lot of difference in those values in v 0.90. But i suggest that you have to show both weight values and the heaviest one counts.

Yes there is

[Foxster]

Yes there is

That's not in the rules but in a later post and you said no more rules.

I suggest you alter your rules if want something other than what's usually used in these type of challenges.

[Streetwind]

Woops... you were supposed to give mass including massless parts? Totally missed that. Normally I'd go and edit my post with a nice and detailed breakdown, but I'm on mobile right now and formatting is a pain.

So the number will have to suffice: 838.5 kg liftoff mass including the batteries.

[Ferdoni]

That's not in the rules but in a later post and you said no more rules.

I suggest you alter your rules if want something other than what's usually used in these type of challenges.

You're right so I did. excuses for being unclear

[Foxster]

Here's a tweaked one to minimise the massless parts and I took a drop of fuel outa one of the tanks as its not needed...

Total mass = 0.738 (massed parts) + 0.235 (massless parts) = 0.973t

Could get away with one engine but its very fiddly to get a one of those engines exactly lined up with the centre of the craft so I gave up for now.

=====

Update

Managed with one engine...

Which brings the total weight down to 0.738+0.09+0.05+0.005=0.883t.

Edited April 21, 2015 by Foxster

[panzer1b]

The smallest SSTO ive ever managed to pull off is 9.5ish tons. Thats because it ofc has to be fully laythe capable, as i never touch SSTOs only to LKO. The smallest i think its even possible to make a SSTO with 5000+dV is somewhere in that range. Then again, for purely LKO, i can see that those massless parts really come in handy (would perhaps a 48-7s be better though as it has more ISP then the mono-engine with some LFO or is that too heavy?).

[Streetwind]

The 48-7S craft I used is minimally lighter than Foxster's monoprop one. But it's so similar that it's just about equal.

Also keep in mind that next monday, all the stats change. Drastically. (Seriously, you habe no idea.) And from what I heard, massless parts will stop being massless. They'll add their mass and drag to the parent part instead of calculating it themselves (or not at all). It was always meant to be that way, it just didn't work properly.

So expect this challenge (any challenge) to require a complete do-over next week

[Ferdoni]

I know! And I will start this challenge over

Thanks everyone!