165 ton stock lifter?

[xtoro]

Trying to push the limits of a lifter and always come up a couple hundred m/s short... Can anyone come up with something efficient? The catch is that the total ship needs to be under 1000 tons, no fuel from the payload can be used, and the last stage needs a bit of fuel and RCS to do a rendezvous once in orbit.

[Progressm]

You'd think that a 16.5% payload fraction on a scalable design, while ambitious, would be doable somehow - I've never gone that high, though. Interested to see what people come up with.

[cantab]

Jet boosters?

[zekes]

Trying to push the limits of a lifter and always come up a couple hundred m/s short... Can anyone come up with something efficient? The catch is that the total ship needs to be under 1000 tons, no fuel from the payload can be used, and the last stage needs a bit of fuel and RCS to do a rendezvous once in orbit.

More first stage- it always works.

I think the Cira is under 1000 tonnes on launch, not really sure....... but it'll do the job and then some.

Because I never really had a special release for this ship, and it's just so amazing, I decided to make a page for it. Introducing the 1500 tonne, 300-tonnes-to-orbit Cira IV.

Cira IV Ultra Heavy Lifter

Designer: Zekes

Status:COMPLETED

Cost: $729,873.60

(KSP-24.0) Our New launcher! The Cira IV can take 300 tonnes OF PURE PAYLOAD to LKO.

Download: https://www./?79xc541f9j040f6

[Stratzenblitz75]

Jet boosters?

Indeed:

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I haven't tested it in 0.25 yet (I'd imagine it would still function the same, but who knows), but in 0.24.2, This thing can lift 165 tons to orbit with fuel to spare. And it only masses 250 tons (with the payload) and burns less than 4000 funds-worth of fuel.

So yeah, if you have no concern for realism whatsoever turbojets are the way to go.

[DrMonte]

You might want to look at "Leviathan Engineering" company http://forum.kerbalspaceprogram.com/threads/58749-Leviathan-Engineering

~3kt to LKO is my record up to date. Though that included mods. There are bigger parts in stock now than in 0.21 so reaching 1kt shouldn't be an issue.

Edited October 31, 2014 by DrMonte

[Axelord FTW]

Indeed:

http://imgur.com/a/k4tpn

I am impressed.

I'm limited to FAR but still. Woa.

[mhoram]

If you want to restrict yourself to non-jet engines only, you can find some inspiration in the Payload Fraction Challenge that features designs with payload fractions of over 20%.

One of my old designs, the Tangent 18 can lift 180 ton while the ships total mass is below 1000 ton.

Also my Lopac 18 can lift 170 ton with a total mass of ~1000 ton.

[capi3101]

Hmm...165 tonne payload, eh?

Yeah, that one defies the standard limits of design a tad bit. Conventional wisdom would say that an asparagus-staged rocket has a 15% payload fraction (the final design would weight 1100 tonnes, which is more than the OP's - I'm going to assume "personally mandated" - weight limit, while a transporter spaceplane can do roughly 25% if you design it right - for a 165 tonne payload, that's a 660 tonne plane, and with conventional wisdom saying 15 tonnes max takeoff wait per turbojet that comes out to no less than 44 Turbojets, so I imagine the part count there would be effin' horrendous...provided the plane itself didn't break the runway as soon as the physics engine kicked in due to its mass.

So with that said...let's try the asparagus option. Temstar had a booster design back in 0.20 that could do 160 tonnes based on his '>asparagus design philosophies of the time (before the days of thrust limiting), so it should be possible to do a booster for 165 tonnes. Based on his philosophy, you'll need an 1,100 tonne rocket (assuming a 15% payload efficiency), with 3795-4032 kN of thrust in the core and 2242-2382 kN of thrust in the boosters (assuming three booster pairs). The boosters are easy - you'll want KR-2Ls there set to between 90-95% thrust each (go with 95%). The core is the tough bit; nothing outputs that much thrust on its own, so you will need an engine cluster there. I'm gonna suggest a KS-25x4 coupled with six Mk-55s; that should give you 3920 kN, which is in the acceptable range. 73.65 tonnes of engines + 165 tonnes payload = 861 tonnes leftover for fuel and extra crap. Say it's all for fuel - dividing the fuel evenly among seven stacks gives 123 tonnes per stack. Three orange tanks plus one X200-16 and one X200-8 (the small and medium 2.5 meter tank) each comes close to that, for 121.5 tonnes per stack, which gives you a 10.85 tonne budget for extra crap like decouplers, I-beams (which you're going to need if you couple those extra large engines with the 2.5 meter tanks), RCS capabilities for the core (use a couple of cylinders - that should be more than enough) and whatever else you need...maybe a probe core and a couple of Z-100s and OX-STAT panels so that when it's all said and done you can deorbit the final stage of the booster and self-clean.

I'll have to test this design to see if it'll make orbit. Unfortunately tonight is Halloween, I've got kids of the appropriate "promote tooth decay" age and I'm at work up until then, so it may be tomorrow before I can try it out. You're welcome to try out the design in the meantime; I'd love to know if I've steered you wrong or not, OP.

[SRV Ron]

This should be placed in the challenge section to come up with a cost efficient design. Easily doable using asparagus design but not cost effective.

[blizzy78]

If you want to restrict yourself to non-jet engines only, you can find some inspiration in the Payload Fraction Challenge that features designs with payload fractions of over 20%.

We should totally revive that thread.

[capi3101]

This should be placed in the challenge section to come up with a cost efficient design. Easily doable using asparagus design but not cost effective.

Not necessarily...I did a set of boosters the other day for a guy who was only lifting twenty-five tonnes, an SSTO rocket and an asparagus. The asparagus design was almost half the cost of the SSTO. Makes me wonder how a transporter spaceplane would fare.

[xtoro]

Thanks for all the replies!

More first stage- it always works.

I think the Cira is under 1000 tonnes on launch, not really sure....... but it'll do the job and then some.

Unfortunately the Cira is 1500t at launch...

Indeed:

http://imgur.com/a/k4tpn

I haven't tested it in 0.25 yet (I'd imagine it would still function the same, but who knows), but in 0.24.2, This thing can lift 165 tons to orbit with fuel to spare. And it only masses 250 tons (with the payload) and burns less than 4000 funds-worth of fuel.

So yeah, if you have no concern for realism whatsoever turbojets are the way to go.

Jets huh? That's a good idea, never thought of that. Definitely going to give it a try just for fun!

You might want to look at "Leviathan Engineering" company http://forum.kerbalspaceprogram.com/threads/58749-Leviathan-Engineering

~3kt to LKO is my record up to date. Though that included mods. There are bigger parts in stock now than in 0.21 so reaching 1kt shouldn't be an issue.

Tried it, but the initial launch mass is too high to add 165t without it being over 1000t on the heaviest lifter under 1kt.

If you want to restrict yourself to non-jet engines only, you can find some inspiration in the Payload Fraction Challenge that features designs with payload fractions of over 20%.

One of my old designs, the Tangent 18 can lift 180 ton while the ships total mass is below 1000 ton.

Also my Lopac 18 can lift 170 ton with a total mass of ~1000 ton.

These are both great! And they do the job. I'm leaning more towards the Lopac 18 as being a little better I think just because of simplicity. I tend to over-engineer everything until it's a giant mess, then start from scratch and do it again a couple more times till the light bulb goes off lol

This should be placed in the challenge section to come up with a cost efficient design. Easily doable using asparagus design but not cost effective.

I think there are already several similar challenges. And I don't really want to manage a challenge because I'm only on here sporadically.

[mhoram]

We should totally revive that thread.

I don't know about that. The previous finished just 9 months ago and the parts did not change that much which means that the results will be in the same range. And with career-mode the focus shifted away to cost-efficient lifters.

If there is enough demand however, I would be willing to host a new payloadfraction challenge.

These are both great! And they do the job. I'm leaning more towards the Lopac 18 as being a little better I think just because of simplicity.

Glad you like them. Be aware that I did not test them yet in v0.25.

[Pecan]

Coincidentally - I am citing mhoram's as an exemplar in the introduction for my next tutorial, "...why I hadn't published any vehicles in the Spacecraft Exchange. The simple answer is that ... those I do use I still don't think are as good for a general audience as some of those that are already published such as Temstar's (somewhat old) Zenith (http://forum.kerbalspaceprogram.com/threads/24787-0-19-1-Zenith-rocket-family) and mhoram's Lopac Lifter (http://forum.kerbalspaceprogram.com/threads/74395-Low-Partcount-Lifters) families."

There are some great engineers around here :-)

[capi3101]

Thought I'd had a solution for the OP there for a minute...had the proofing payload set to the wrong mass......well, back to the drawing board.

EDIT: Okay...will this do?

Basically this is the design I described earlier today, except that each booster rocket received an X200-32 and an X200-8 instead of a third orange tank. There are 16 RCS blocks in the core with two roundified tanks for fuel, an RC-L01 probe core and a Z-4k battery for self-control. The boosters are on the ends of XL girder segments and use Hydraulic Detachment Manifolds for staging boosted with single Sepratrons. 995 tonnes as is - for a payload fraction of 16.58%.

Edited November 1, 2014 by capi3101

[Tokay Gris]

Not necessarily...I did a set of boosters the other day for a guy who was only lifting twenty-five tonnes, an SSTO rocket and an asparagus. The asparagus design was almost half the cost of the SSTO.

Depending on how you design the SSTO, you could get most of the initial cost back on retrieval.

I have a SSTO currently in use that costs just under 60.000 and that is just the fuel. The rest can be retrieved. This current design can get about 100 tons to orbit, then land almost pinpoint on the launchpad again (using MechJeb).

(That can be a problem, because you need to retrieve the launch stabilizers first or you can't land there)

[Fingal]

If you want something early on the tech tree, my "Early Season Asparagus" launcher can manage about 160 tons:

[Laie]

Indeed:

http://imgur.com/a/k4tpn

How do you do that? I've got one with a very similar propulsion system (24 jets 3 nukes for 125t), but it takes twice as long to get to orbit, and eats like 20k worth of fuel.

[SpaceSphereOfDeath]

If you want something early on the tech tree, my "Early Season Asparagus" launcher can manage about 160 tons:

http://i60.tinypic.com/24qv7s0.png

Download link, I want to see how that thing actually works.

[Stratzenblitz75]

How do you do that? I've got one with a very similar propulsion system (24 jets 3 nukes for 125t), but it takes twice as long to get to orbit, and eats like 20k worth of fuel.

Are you using this trick? Placing the Engines and Intakes one by one not only prevents flame outs, it also makes the jet engines more powerful (you can see that in a test I preformed in that link). Also, how many intakes are you running? The FLS Titan runs 2 intakes per engine for a total of 32 engines and 64 intakes. I found that two intakes per engine on a VTLV craft should be enough to air-hog your way to orbit. Or maybe 0.25 changed things, as I've said, I haven't tested it 0.25 yet.

Edited November 1, 2014 by Stratzenblitz75

[Fingal]

Download link, I want to see how that thing actually works.

Here it is: https://www.dropbox.com/s/iz8vu44wuhljcg4/Early%20Season%20Asparagus.craft?dl=0

It's what my wife built when she was bored one evening. She built two others as well, one for 500 tons and one for 1550 tons. The later has a slightly unfortunate staging order that bears the unmistakeable signature of Wernher Von Kerbal. Link is at https://www.dropbox.com/s/4ah8yasn2xdgwtl/Asparagus%20Launchers.rar?dl=0

[Laie]

Are you using this trick?

Of course I do -- otherwise the jets would die too early for the nukes to make orbit.

(click for lots of pictures from the ascent -- was a challenge submission).

If you could have a look and tell me where I'm taking a wrong turn?

[kStrout]

I built a 150ton heavy lifter when 0.23.5 came out, don't know if it was below 1000tons.

[Jouni]

I built a 150ton heavy lifter when 0.23.5 came out, don't know if it was below 1000tons.

In 0.23.5, it was easy to build a 150-tonne lifter with launch mass a bit over 950 tonnes. You just used four LFBs with two extra orange tanks each, a lower stage with a KS-25x4 engine cluster and three S3-14400 fuel tanks, and an upper stage with a KR-2L engine and a S3-14400 fuel tank. There was no need for any fuel lines or complicated staging. Then the LFBs got nerfed in 0.24, and the design stopped working. The boosters burned out too soon, and the lower stage had too low TWR on its own.