Efficiency challenge - first time poster

[pseudorealityx]

So my first post on the forum... and didn't see a similar thing listed.

A couple of friends have been trying to challenge ourselves to make the most efficient rockets. Started with getting to the Mun, then Eve, etc.

Goal: Land a Kerbal on Laythe with the highest ratio of (tons on Laythe/tons on launch pad on Kerbin)

Restrictions:

1) Stock parts. (We're relatively novice users, so if use plug-ins, fancy calculators, etc, at least mention it).

2) Vertical take off

3) Kerbal must be contained in a stock 'pod/can'.

4) Mass weighed based on the ship being intact after landing on Laythe. If something breaks off, it doesn't count.

[edit]

5) No refueling/docking from another ship during the mission. Goal is a single spacecraft makes the journey.

6) Original thought was no spaceplanes, but if folks are interested in that, feel free to post that and we can have 2 'leaders'. Let's define 'spaceplanes' as a craft that uses aerodynamic lift in an atmosphere to avoid a traditional vertical launch with a "regular gravity turn"

/[edit]

Current effort:

17.4 tons on Laythe.

131.93 tons on the launch pad on Kerbin

Go!

Edited June 28, 2014 by pseudorealityx
clarification

[Pecan]

Laythe is an interesting target since it's the only place other than Kerbin with an oxygen atmosphere. That means jets will work there and, therefore, spaceplanes are practical. Although you've specified vertical take-off that doesn't preclude a tail-sitter design that lifts from the pad then transitions to 'normal' spaceplane horizontal flight. Such an aircraft, refuelled in space - possibly in LKO and LLO, will have a very high payload fraction, being almost 100% (the only 'loss' being the fuel used during descent to Laythe, if any). If that's not the sort of thing you're looking for you might want to make more exclusion rules ;-)

(Personally, I'd like to see people's spaceplane designs as well, but it's your thread).

[pseudorealityx]

Thanks for the input. I'll edit the original thread.

[Vector]

What's the criterion for a non-spaceplane? I would say use of jets is the difference, but it's a shame on an efficiency challenge since jets can be tremendously efficient.

Also, just an observation, it would seem there's no point to staging, since any dead weight (empty tanks, etc) counts as payload according to the measurement method.

[pseudorealityx]

What's the criterion for a non-spaceplane? I would say use of jets is the difference, but it's a shame on an efficiency challenge since jets can be tremendously efficient.

Also, just an observation, it would seem there's no point to staging, since any dead weight (empty tanks, etc) counts as payload according to the measurement method.

Edited the original post to add a definition of space plane. A plane by definition uses aerodynamic lift. There have been rocket powered planes (Me-163 for example), but they all use wings of some sort.

I'm obviously not as experienced as many of you on KSP, but I think staging is somewhat important. The more 'dead' weight you bring with you, the more fuel you use. And any fuel you use is weight you cannot land with.

For the sake of sanity, I was thinking of not allowing ion engines, but in the case that someone who hasn't posted is actually attempting this WITH an ion engine, I'll wait a day(?) to update the rules. Anyone has any comments on that, let me know.

By the way, thanks for posting. First Challenge and posts on KSP, so the help is appreciated.

[immelman]

What's the criterion for a non-spaceplane? I would say use of jets is the difference, but it's a shame on an efficiency challenge since jets can be tremendously efficient.

Also, just an observation, it would seem there's no point to staging, since any dead weight (empty tanks, etc) counts as payload according to the measurement method.

I'd agree, taking off vertically using jets can be almost as efficient as a horizontal spaceplane. You can take off using lift and a TWR < 1, but burn more fuel reaching 15 km, when turbojets become more efficient.

Of course some sort of ion glider would be even more efficient

[No one]

Are we allowed to use air intakes to artificially increase the final mass?

Because if so it would be theoretically possible to make something with more mass on Laythe than on Kerbin.

[pseudorealityx]

Are we allowed to use air intakes to artificially increase the final mass?

Because if so it would be theoretically possible to make something with more mass on Laythe than on Kerbin.

First, I'm apparently ignorant of the glitch that allows that. Care to explain?

And second, no. I was hoping this challenge would about trying to be smart about building, flying, and landing a rocket. Not how to abuse oddball traits of KSP.

[No one]

First, I'm apparently ignorant of the glitch that allows that. Care to explain?

And second, no. I was hoping this challenge would about trying to be smart about building, flying, and landing a rocket. Not how to abuse oddball traits of KSP.

It's not a glitch. Intake air has mass. If you start with all your intakes empty, and end with all your intakes filled (Fill them up on Laythe), you can end with more mass than you started with.

[pseudorealityx]

Which is an "oddball" trait of KSP. So no. Within reason, the goal is to make something that's basically logical to build as a real spaceship.

[Tsevion]

Here we go... it's an SSTO, but I launch it vertically for your pleasure, the aerodynamic lift isn't really needed for takeoff, it's much more for landing. I actually had already made this as part of a goal of mine to build a stylish and compact SSTO.

6.16t at Launch

5.51t on Laythe

4.84t on return to KSC

Javascript is disabled. View full album

[pseudorealityx]

Very cool. From what I can see, you've got the 1 turbojet and 4x ion engines. Am I missing something on how you went from 15k (when the jets died) to orbit?

Edited June 30, 2014 by pseudorealityx

[Rakaydos]

Very cool. From what I can see, you've got the 1 turbojet and 4x ion engines. Am I missing something on how you went from 15k (when the jets died) to orbit?

Apparently you missed the image with the turbojet still producing 36kN of thrust at 2/3 throttle, at 38 KM altitude and orbital speed. having a single jet makes it immune to asymetic flameouts.

[pseudorealityx]

Apparently you missed the image with the turbojet still producing 36kN of thrust at 2/3 throttle, at 38 KM altitude and orbital speed. having a single jet makes it immune to asymetic flameouts.

I did miss that.... how many intakes does it take to get to 38km with 36kN of thrust at 2/3rd throttle? I see 4?

[cr055H41rz]

As soon as it said sstos optional I thought: Watch everyones gonna be making SSTOs

Low and behold the one entry is an SSTO

[Starwhip]

I'll attempt this later. It's 1:33 AM right now.

I've actually never been to Laythe before. First time for everything, I suppose.

[r_rolo1]

Hum, I might try this out ... I remember the good ol'days of the aerospike, when I took this to Laythe , and maybe a somewhat modified version could make it there anyway ...

[Tsevion]

I did miss that.... how many intakes does it take to get to 38km with 36kN of thrust at 2/3rd throttle? I see 4?

Ayup, just 4. Probably do-able with 2, but 4 makes it easier. As long as you keep lowering the throttle you can get quite high... I think I finally stopped thrusting at around 50km. I screen-shotted the final orbit from the jet, you can see it, and can see I haven't used any Xenon yet.

Oh, I should probably include the Craft File

Edited July 8, 2014 by Tsevion
Added Craft file