Lightest Eve Launcher

[clems]

There has been a similar challenge 5 years ago. Since then a lot has changed in KSP. So I start a new challenge for the lightest vehicle that can bring a Kerbal from Eve sea level to stable orbit (> 90 km x 90 km).
Stock parts only. A capsule is not required, but stock parts only (usage of extensions like Making History and Breaking Ground is allowed).

MechJeb and KOS mods are also allowed.

Three categories:

1) without Kerbal Jet Pack usage

2) with Jet Pack usage

3) Open category: including Kraken drives, exploits, infiniglides, worm holes etc.

Please provide screenshots of vehicle in Assembly Building, on Eve ground level and critcal mission phases (if that applies).

If you have something lighter than mine (7489 kg including Valentina), a craft file and a video is appreciated.

Edited December 2, 2019 by clems
added cat 3

[dnbattley]

I'm assuming that Kraken drives are disallowed?

Nice challenge though: I haven't looked at Eve in a while...

[Pds314]

Hmm.... I know some aerodynamic shenanigans that might make it possible to get fairly low masses.

[clems]

8 hours ago, dnbattley said:

I'm assuming that Kraken drives are disallowed?

Nice challenge though: I haven't looked at Eve in a while...

Good point. I have added an extra category for it ;-)

[dnbattley]

Well I didn't want the first submission to be a physics-abusing design, but in the interests of keeping this fun challenge bumped I present "The Eve Lawn Dart" at 573kg. It is not just possible, but relatively easy to reduce this already very low weight further, but this would be at the expense of such "extras" as: protecting the Kerbal from heating, a solar panel for topping up the battery, and having to fight the flight characteristics without fins

Summary details below:

Spoiler

 

Slightly longer mission report:

http://www.imgur.com/a/5bqnIwJ

 

[dnbattley]

Craft file: https://kerbalx.com/dnbattley/EVE-Ascender

[clems]

Hm. Works really well. Thanks!
So far I have experienced the Kraken only in a destructive way.
Thanks for providing this. I guess the core of the drive is the wheel. Funny ;-)

Anyway, this is more like using dark magic.

So I am looking forward to more traditional engineering solutions, too ;-)

 

My traditional solution looks like this:

Looks simple, but took at least 30 hours of testing and optimizing to make it work.

[The Minmus Derp]

Wow! what's the not traditional solution?

[Muetdhiver]

On ‎12‎/‎7‎/‎2019 at 10:37 AM, clems said:

Hm. Works really well. Thanks!
So far I have experienced the Kraken only in a destructive way.
Thanks for providing this. I guess the core of the drive is the wheel. Funny ;-)

Anyway, this is more like using dark magic.

So I am looking forward to more traditional engineering solutions, too ;-)

 

My traditional solution looks like this:

Looks simple, but took at least 30 hours of testing and optimizing to make it work.

This is beautifull in a weird way. And yeah, roton like designs are devilish to make work proper.

[michaelbezos1]

Do you know how to launch the spacecraft after pressing the space ?? 

Please help 

[herbal space program]

Good post! It's great to see people investigating the awesome potential of the BG rotor parts to make getting off Eve something other than a booster-spamming contest. For my part, I'm working on a prop-powered Eve sea-level SSTO:

 

 

It makes Kerbin orbit with >2km/s using nukes:

And flies pretty well on Duna too:

I'll need to create a non-nuke version for Eve, but with that much dV on Kerbin orbit, I'm pretty optimistic it will work!

[DRAG0Nmon]

@herbal space program that certainly is an interesting wing design

[herbal space program]

13 hours ago, DRAG0Nmon said:

@herbal space program that certainly is an interesting wing design

It certainly looks like it was slapped together by my drunken chimpanzee avatar if that's what you mean!  I actually started over completely 5 times in this process.  Each time I told myself I'll make it look good this time, but then each time, after like 30  test flights and trips back to the SPH, I ended up in about the same dorky place appearance-wise. Once I really get it flying the way I want it to, I'll probably set about remedying the fact that it looks like a flying exploded diagram. There's just a lot to consider, and having all the engines assymetrical makes moving some things around a real pain in the end that should not point towards space.

Edited December 21, 2019 by herbal space program

[Lt_Duckweed]

On 12/20/2019 at 8:44 PM, herbal space program said:

Good post! It's great to see people investigating the awesome potential of the BG rotor parts to make getting off Eve something other than a booster-spamming contest. For my part, I'm working on a prop-powered Eve sea-level SSTO:

 

 

It makes Kerbin orbit with >2km/s using nukes:

And flies pretty well on Duna too:

I'll need to create a non-nuke version for Eve, but with that much dV on Kerbin orbit, I'm pretty optimistic it will work!

Keeping the nukes might not be a bad idea, as they can really help with efficiency during the parts of the flight post 20km or so.  For my part I've been exploring weather a sea level eve SSTO is possible with just props and nukes.  I've SSTO'd every other body in the system (Yes that includes Jool) using some combination of nukes and props so defeating Eve is a pride point for me now.

[herbal space program]

9 hours ago, Lt_Duckweed said:

Keeping the nukes might not be a bad idea, as they can really help with efficiency during the parts of the flight post 20km or so.  For my part I've been exploring weather a sea level eve SSTO is possible with just props and nukes.  I've SSTO'd every other body in the system (Yes that includes Jool) using some combination of nukes and props so defeating Eve is a pride point for me now.

The nukes are great on Kerbin or Duna, but I've found that in Eve's high gravity TWR is so critical they're generally not that helpful in making orbit.  Since this ship makes Kerbin orbit with >2km/sec, I'll still have >1km/sec left if I swap them for aerospikes and replace the extra weight with fuel. Bare Wolfhounds might represent  a good compromise in that regard as well, which I have not yet investigated.  Also, out of curiosity, how do you define SSTO-ing on Jool?

Edited December 22, 2019 by herbal space program

[Lt_Duckweed]

5 hours ago, herbal space program said:

The nukes are great on Kerbin or Duna, but I've found that in Eve's high gravity TWR is so critical they're generally not that helpful in making orbit.  Since this ship makes Kerbin orbit with >2km/sec, I'll still have >1km/sec left if I swap them for aerospikes and replace the extra weight with fuel. Bare Wolfhounds might represent  a good compromise in that regard as well, which I have not yet investigated.  Also, out of curiosity, how do you define SSTO-ing on Jool?

Start in orbit of Jool, go to Jool 0 altitude, return to Jool orbit, without staging or otherwise getting rid of parts.

[herbal space program]

1 hour ago, Lt_Duckweed said:

Start in orbit of Jool, go to Jool 0 altitude, return to Jool orbit, without staging or otherwise getting rid of parts.

I was going to protest that must be impossible, but then I looked at the Wiki for Jool and saw that its "surface" gravity is only 7.85 m/s², like Laythe's, in spite of having an orbital velocity of >3 km/s. I'll have to give it a try with my current plane, as I think it'll probably be about the same as Kerbin to get off of between the higher OV and the lower gravity. Eve is a different movie though. It has more than twice that surface gravity at 16.7 m/s², which means you need a whole lot of TWR to avoid plunging back into the soup.  In that gravity, the Nerv engines alone only have a TWR of 1.2, so I never found them so helpful in making orbit. I still think it's totally doable though!

Edited December 22, 2019 by herbal space program

[Lt_Duckweed]

31 minutes ago, herbal space program said:

I was going to protest that must be impossible, but then I looked at the Wiki for Jool and saw that its "surface" gravity is only 7.85 m/s², like Laythe's, in spite of having an orbital velocity of >3 km/s. I'll have to give it a try with my current plane, as I think it'll probably be about the same as Kerbin to get off of between the higher OV and the lower gravity. Eve is a different movie though. It has more than twice that surface gravity at 16.7 m/s², which means you need a whole lot of TWR to avoid plunging back into the soup.  In that gravity, the Nerv engines alone only have a TWR of 1.2, so I never found them so helpful in making orbit. I still think it's totally doable though!

You actually cannot get off Jool in an SSTO without Nervs, as you need around 8km/s of delta-v.  To date I am the only person who has done a Jool SSTO so I'd love to welcome others to the club!

[paul23]

30 minutes ago, Lt_Duckweed said:

You actually cannot get off Jool in an SSTO without Nervs, as you need around 8km/s of delta-v.  To date I am the only person who has done a Jool SSTO so I'd love to welcome others to the club!

Using a mainsail, you have 8000 = 310 *  9.81 * ln(m0/mf) or:

m0/mf = e^(8000/(310*9.81)) = 14

so total weight needs to be more than 14 times the operating empty weight.

 

Looking at the tank: Kerbodyne S3-14400:  empty weight is 9 tonnes, full weight is 81 tonnes. So the maximum fraction m0/mf we can get is 9. So this means we do indeed need a minimal specific impulse of:

 

8000 = Isp * 9.81 * ln(9)

Isp = 371.147 In stock outside the conventional engine ranges.

 

There is a slightly more efficient tank: R-4 'Dumpling' External Tank. It's a small tank so you'll have to spam those. But this tank has a fuel fraction of 12.

8000 = Isp * 9.81 * ln(12)
Isp = 328.179

 

Which is "almost" possible using the skipper,  and possible with the poodle, though then you're back at bad thrust levels.

[herbal space program]

46 minutes ago, paul23 said:

Which is "almost" possible using the skipper,  and possible with the poodle, though then you're back at bad thrust levels.

The Wolfhound from MH has an ISP of 380, so that would technically be high enough, although its TWR is nothing to write home about. My prior statement about Nervs however was based on an inaccurate idea of how strong Jool's gravity field is. They would definitely have enough TWR to be useful at only 7.85 m/s² of downward acceleration. And as I just went there with my plane using HyperEdit and saw that a 200 km circular orbit is like 5.6 km/s, I don't doubt that it actually takes close to 8 km/s of dV to make orbit. Those props are great for lifting you out of the worst of the soup, but they don't get you going very fast.

Edited December 23, 2019 by herbal space program

[Lt_Duckweed]

3 hours ago, herbal space program said:

The Wolfhound from MH has an ISP of 380, so that would technically be high enough, although its TWR is nothing to write home about. My prior statement about Nervs however was based on an inaccurate idea of how strong Jool's gravity field is. They would definitely have enough TWR to be useful at only 7.85 m/s² of downward acceleration. And as I just went there with my plane using HyperEdit and saw that a 200 km circular orbit is like 5.6 km/s, I don't doubt that it actually takes close to 8 km/s of dV to make orbit. Those props are great for lifting you out of the worst of the soup, but they don't get you going very fast.

Pretty much spot on.  You have to use props to climb to 115km-118km  and about 450-500m/s on props.  Once there you have between 550 and 600 specific impulse on the nervs, and a twr of just under 0.3, from there you burn the nukes and use the props up to around 800m/s at something like 125km, then my setups close the props off in a payload bay to reduce drag.  From there it's up to the nukes alone to burn from 800m/s to 5700m/s.  The toughest part is getting past the sound barrier at 900m/s (Hydrogen atmosphere), I usually do that in a shallow dive.  Once you get past that it's smooth sailing.

[herbal space program]

19 hours ago, Lt_Duckweed said:

Pretty much spot on.  You have to use props to climb to 115km-118km  and about 450-500m/s on props.  Once there you have between 550 and 600 specific impulse on the nervs, and a twr of just under 0.3, from there you burn the nukes and use the props up to around 800m/s at something like 125km, then my setups close the props off in a payload bay to reduce drag.  From there it's up to the nukes alone to burn from 800m/s to 5700m/s.  The toughest part is getting past the sound barrier at 900m/s (Hydrogen atmosphere), I usually do that in a shallow dive.  Once you get past that it's smooth sailing.

I took a look at your SSTO, and while it incorporates a number of really good ideas like mounting your props in service bays and putting a bunch of stuff behind fairings, to me the degree of part clipping involved is  disqualifying , because you're basically just cheating the drag model.  For the most part,  challenge issuers for this sort of thing (including me) allow part clipping only if it does not put solid, massive parts substantially inside each other.  So for example if you want to mount multiple engines with large bells into less space than they really fit, moderately clipping just the bells into each other might be considered OK, but not mashing all the engine bodies together, as you surely must have done with all those Nervs. When I went to the SPH to try to imitate what you had,I found  that while you apparently used  2.5m fairings to house your tanks, etc., not even 5m fairings of that shape would actually fit all that stuff inside without a lot of clipping. To me that's pretty egregious, especially if we're talking about Mk1 LF fuselages, which already have quite a high mass/drag ratio. So although I'm definitely impressed, I would not consider that craft as really demonstrating that a Jool SSTO is possible without doing something that's generally considered cheating.

Edited December 24, 2019 by herbal space program

[clems]

On 12/13/2019 at 12:36 AM, The Minmus Derp said:

Wow! what's the not traditional solution?

I meant: my solution, which is more traditional than using a kraken drive.

Although what I find interesting about my design is the fact that it is using only a single rocket engine. That is located in the top section and the exhaust goes through the donut tanks. So these tanks can be jettisoned one by one when empty while the engine stays. Makes for a pretty efficient multi-stage rocket.

[The Minmus Derp]

Wow! That is so clever! But when I last checked, the donut tanks didn't have holes in the collision box for kerbals/engine exhaust to fall through. Is that a new thing in 1.8?

[qzgy]

1 hour ago, The Minmus Derp said:

Wow! That is so clever! But when I last checked, the donut tanks didn't have holes in the collision box for kerbals/engine exhaust to fall through. Is that a new thing in 1.8?

Think even earlier, whenever they introduced the new donut tank. Don't quote me on it though.