LackLuster. The little chemical SSTO that could...

[YargJay9991]

Congrats Rune!

This lovely craft featured on my Spacecraft Friday Edition! Check it out here.

Happy Flying

YargJay9991

[How2FoldSoup]

Very good-looking one! Just a tiny correction: aerospikes have awesome isp, especially at ground level. The thing they lack (compared with, say, the Mammoth) is TWR, actually. And low TWR in SSTOs means a lot of gravity losses, meaning reaching LEO is more around 4km/s rather than 3,5. Or, a low fuel fraction if you just chuck on a ton of spikes on account of all that engine weight. Just some food for thought, one of those engineering trades that takes some getting used to.

I only meant compared to pre-1.0 days where they had ~385s and it was a dream to fly with them. I do enjoy the Isp they have at SL. That's actually one of the problems I was having with them was the low TWR. That's why I packed on so many engines. I'm struggling to come up with a solution although just as I'm replying I think I may have it. It will be a balancing of my solution here(many spikes) and my first experimental build which used a mix of spikes and sparks.

[Rune]

Congrats Rune!

This lovely craft featured on my Spacecraft Friday Edition! Check it out here.

Happy Flying

YargJay9991

Great!

I only meant compared to pre-1.0 days where they had ~385s and it was a dream to fly with them. I do enjoy the Isp they have at SL. That's actually one of the problems I was having with them was the low TWR. That's why I packed on so many engines. I'm struggling to come up with a solution although just as I'm replying I think I may have it. It will be a balancing of my solution here(many spikes) and my first experimental build which used a mix of spikes and sparks.

Oh, yeah, all engines used to be much better. Then again, the souposphere ate most of the benefits... In many ways chemical SSTOs were harder back then. And of course, if you want a bigger payload, you have to add more engines and fuel to bring the mass ratio up. I hope it goes well!

Rune. I totally didn't expect it to make the SCF!

[Paranoid Shark]

Rune,

Made it to orbit with my Mk3, however the fuel routing is still a bit messed up. I have to manually move fuel around to stop the yawing around.

I have set it up with 9 spikes on the bottom, and then all the fuel running into the bottom tank so that all the engines have the same amount of fuel. The latest problem is that the top tank is supposed to drain into the port and starboard tanks, however even though I have it set up symmetrically it drains the starboard tanks whilst the top tanks still have fuel in them.

Do I need to have a fuel line going through the cargo bay directly linking the top and bottom tanks?

Still need to put some RCS control in it, but have successfully made it to orbit and back 3 times now!

[Rune]

Rune,

Made it to orbit with my Mk3, however the fuel routing is still a bit messed up. I have to manually move fuel around to stop the yawing around.

I have set it up with 9 spikes on the bottom, and then all the fuel running into the bottom tank so that all the engines have the same amount of fuel. The latest problem is that the top tank is supposed to drain into the port and starboard tanks, however even though I have it set up symmetrically it drains the starboard tanks whilst the top tanks still have fuel in them.

Do I need to have a fuel line going through the cargo bay directly linking the top and bottom tanks?

Still need to put some RCS control in it, but have successfully made it to orbit and back 3 times now!

Well, to be honest, I think I am quite lost now with your issue, then. The bottom tank should be the first draining so the stability is maintained, and the top tank be the last one to go, ideally... take into account that node connections will also count as fuel routes, that might be the issue here. Or it could be a symmetry bug (happens all the time), or you are just doing something different with your fuel route... In any case, I think it's time for that pm with an email so I can take a look at it myself... or, you know, you could take about the same time to make a mediafire account (or something similar) and put a link here, and then even if I don't have the time perhaps some other industrious kerbal will take a look at it and fix it just as well.

Don't get too upset you couldn't figure it out, though... fuel routing is a quite unintuitive art, it took me a lot of time to learn the tricks and still I sometimes boop it up.

Rune. For more information, I defer to the master.

[How2FoldSoup]

Hey Rune,

I worked on it a bit last night and was just using MJ to fine tune the ascent to see what she was capable with a better pilot than me. This was the best ascent I was able to make. She's also a full 30t lighter than my previous attempt so I'll call that a huge improvement.

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[Rune]

Hey Rune,

I worked on it a bit last night and was just using MJ to fine tune the ascent to see what she was capable with a better pilot than me. This was the best ascent I was able to make. She's also a full 30t lighter than my previous attempt so I'll call that a huge improvement.

http://imgur.com/a/tDCuC

That looks awesome! Much better indeed than the Heinlein, actually (albeit with a slightly higher par count and launch mass... but everything has a prize, right? ). If I may suggest it, though, I'd move the capsule a smidge down with the translation gizmo so you get it flush with the body. Other than that, I actually wish I had come up with using those tanks myself, even in spite of their lower fuel fraction.

Rune. Keep it up!

[How2FoldSoup]

That looks awesome! Much better indeed than the Heinlein, actually (albeit with a slightly higher par count and launch mass... but everything has a prize, right? ). If I may suggest it, though, I'd move the capsule a smidge down with the translation gizmo so you get it flush with the body. Other than that, I actually wish I had come up with using those tanks myself, even in spite of their lower fuel fraction.

Rune. Keep it up!

Thanks! A good portion of the part count is a 1.25m service bay between the mk2 adaptors and the nose cone(just translated down) with a battery and solar panel in each. That alone x6 costs me a solid 18 parts plus 4x4 verniers but they are a necessary evil . Great idea about the capsule though! I'm going to do that immediately.

I also forgot to mention she's 85t on the pad so she's a bit heavy but isn't the worst to send 3 kerbals to LKO. It's around 4.2km/s fully fueled in orbit and should be capable of landing and returning on anything except Eve.

Edited October 31, 2015 by How2FoldSoup

[Kryten 2X4B 523P]

Some really nice little ships here. Had a short break, and this inspired me to try my own version -

Still a WIP, and not as nice looking as some of the above (much more functional), but heres mine.

It can hit a 100km orbit with between 300 - 400 m/s depending how the launch goes, so functionally thats 200 m/s minimum for orbital ops, allowing for enough fuel to deorbit. Just enough for a rendezvous with my station at 150km.

I dumped the fins and use the airbrakes for course correction as its pretty stable going up. Of course, they also help coming back down. The M2 Lander Can means its a little on the fragile side but can recover 2 crew, hence the 4 chutes which just brings it in safely on a flat surface.

May also be useful for orbital rescues.

Totally stole the landing leg config, didnt know they would work that way round!

And sorry Rune, cant spread any more rep around at the moment, but thanks for the inspiration :-)

[Rune]

And sorry Rune, cant spread any more rep around at the moment, but thanks for the inspiration :-)

You are very welcome! I love how this thread has inspired so many people to try their hand at it... in that respect, this is one of my most successful ships, ever!

Rune. It's almost turned into a showcase thread!

[Threadsinger]

[quote name='How2FoldSoup']Hey Rune,

I worked on it a bit last night and was just using MJ to fine tune the ascent to see what she was capable with a better pilot than me. This was the best ascent I was able to make. She's also a full 30t lighter than my previous attempt so I'll call that a huge improvement.

[url]http://imgur.com/a/tDCuC[/url][/QUOTE]

That thing looks awesome. Love the lines.

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Alright, I was tweaking my version inspired by the Lackluster, and, well, this happened:

[img]http://i.imgur.com/1Vggk95.jpg[/img]

New design. Feeling lazy - using MechJeb. Some command part wierdness. Fuel routing is wrong, I know, I know. Turned toward the VAB - and went [I]through[/I] the building. Mostly intact.

Stared for a minute or two as the remaining engine kept spinning it around through the flaming wreckage of the former VAB. Then I decided Jeb was not going to go to space today and hit ALT-F4.

(Still working on that fusion SSTO variant, currently doing a new save and need to finish the "modern" day tech tree before I start unlocking anything powered by He3+... Clearly more R&D on the chemical stuff is advisable first..)

[Raptor9]

Apparently I must spread some rep around before giving it to Rune again. That rocket on the OP, very cool. Reminds me of the McDonnell Douglas DC-X "Delta Clipper".

I'm gonna have to figure out how to make my own simple vertical SSTO rocket now. Sheesh...another item on my KSP To-Do list. Thanks. :wink:

[Rune]

[quote name='Threadsinger']That thing looks awesome. Love the lines.

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Alright, I was tweaking my version inspired by the Lackluster, and, well, this happened:

[url]http://i.imgur.com/1Vggk95.jpg[/url]

New design. Feeling lazy - using MechJeb. Some command part wierdness. Fuel routing is wrong, I know, I know. Turned toward the VAB - and went [I]through[/I] the building. Mostly intact.

Stared for a minute or two as the remaining engine kept spinning it around through the flaming wreckage of the former VAB. Then I decided Jeb was not going to go to space today and hit ALT-F4.

(Still working on that fusion SSTO variant, currently doing a new save and need to finish the "modern" day tech tree before I start unlocking anything powered by He3+... Clearly more R&D on the chemical stuff is advisable first..)[/QUOTE]

Hehe, R&D is fun! Just to help out a bit: that looks like you are adding a bit more fuel to the thing, and that could likely lower your TWR too much to make orbit... Anyhow, [I]if[/I] you can take off without adding more engines, the fuel line arrangement that I had was like this: two lines from the upper tank to two side tanks (the ones that support the engines), then inside the lower tank another two lines, placed without symmetry, going from these side tanks to the unconnected two that make "up" and "down". Oh, and if you need a bit more oomph as you increase weight, you could always put another spike in the middle, but in that case I either wouldn't bother routing fuel to it, and let it work against the other four, or run a couple lines from the same two side tanks that receive fuel first in queue. Or, you know, re-engine the whole thing to use a single Vector, that should work too...

[quote name='Raptor9']Apparently I must spread some rep around before giving it to Rune again. That rocket on the OP, very cool. Reminds me of the McDonnell Douglas DC-X "Delta Clipper".

I'm gonna have to figure out how to make my own simple vertical SSTO rocket now. Sheesh...another item on my KSP To-Do list. Thanks. :wink:[/QUOTE]

That exactly the look I was going for, so thanks to you too!


Rune. Chemical SSTOs are trickier than they seem.

[Frozen_Heart]

Still not sure how all you people are making pure rocket SSTOs. Even without payload mine can only just limp into orbit. Launching with a TWR of 1.1 and almost all of it is fuel.

[Majorjim!]

[quote name='Frozen_Heart']Still not sure how all you people are making pure rocket SSTOs. Even without payload mine can only just limp into orbit. Launching with a TWR of 1.1 and almost all of it is fuel.[/QUOTE]

You didn't cheat fuel into fuel! :D Edited November 24, 2015 by Majorjim
Just teasing Rune

[Threadsinger]

[quote name='Frozen_Heart']Still not sure how all you people are making pure rocket SSTOs. Even without payload mine can only just limp into orbit. Launching with a TWR of 1.1 and almost all of it is fuel.[/QUOTE]

Mine also only "limps" to orbit, (you know, if it actually makes it... still working on the MJ parameters) just enough to technically make it stable (>70K), but not really enough to dock at anything other than a 73K fuel depot. And if the timing is off, that's a lot of orbits to wait for an intercept. The margins are razor thin.

It's fun to design and test though, and see if you can succeed. IANARS, so for most of my routine use of Rune's platform, I toss on a 'chuted drop tank or booster for convenience. I'm also testing a non-parachute/no fin variant which lands under power to save weight and improve appearance - if only there was a right angle vernor RCS...

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[quote name='Majorjim']You didn't cheat fuel into fuel! :D[/QUOTE]

Hah, probably true. I am trying to build one without the clipped tanks to see if it can be done though... darn things looks too tall, aesthetically.

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Yes, I was testing using those elongated adaptor tanks instead of the shorter ones in your craft file. Just for fun. The fuel routing I noticed on liftoff, I was about to revert to the VAB when I saw the imminent collision and decided to see what happens.

For science.

(A supersized aerospike would be neat too...)

[Rune]

[quote name='Frozen_Heart']Still not sure how all you people are making pure rocket SSTOs. Even without payload mine can only just limp into orbit. Launching with a TWR of 1.1 and almost all of it is fuel.[/QUOTE]

Efficient tanking and an absolute minimum of structural crap. Oh, and super-efficient high TWR engines help, too. BTW, TWR is more important than it seems. That low TWR on liftoff might be what's killing you... a SSTO needs [I]much[/I] less dV if it gets off the pad quickly... try building something with TWR 1.5.

[quote name='Threadsinger']Mine also only "limps" to orbit, (you know, if it actually makes it... still working on the MJ parameters) just enough to technically make it stable (>70K), but not really enough to dock at anything other than a 73K fuel depot. And if the timing is off, that's a lot of orbits to wait for an intercept. The margins are razor thin.

It's fun to design and test though, and see if you can succeed. IANARS, so for most of my routine use of Rune's platform, I toss on a 'chuted drop tank or booster for convenience. I'm also testing a non-parachute/no fin variant which lands under power to save weight and improve appearance - if only there was a right angle vernor RCS...[/QUOTE]

They all do! Chemical SSTOing is [I]hard[/I], and it takes an almost-perfect gravity turn. The great thing is, it's quick and you learn tons of things flying them!

[quote name='Threadsinger'](A supersized aerospike would be neat too...)[/QUOTE]
I believe you are referring to the Vector ;)


Rune. A single Vector would lift a Heinlein... more efficiently and with higher TWR and gimbal.

[How2FoldSoup]

[quote name='Rune']


Rune. A single Vector would lift a Heinlein... more efficiently and with higher TWR and gimbal.[/QUOTE]

Agreed! I posted this in the SSTO thread already but I wanted to test out the vector on my older designs but instead just build one around the vector. It's super broken(In my opinion, anyways). This has 26 parts and took me 5 minutes to throw together as a proof of concept and still had 600m/s left in the tanks in a 100x100 orbit. I'm pretty sure you could make some very interesting chemical SSTO's with it. It's got potential. It also has a TWR of 1.6 on the pad which allows you to scoot out of the atmosphere pretty quickly.


[img]http://i.imgur.com/9PFLIAG.png[/img]

[Rune]

[quote name='How2FoldSoup']Agreed! I posted this in the SSTO thread already but I wanted to test out the vector on my older designs but instead just build one around the vector. It's super broken(In my opinion, anyways). This has 26 parts and took me 5 minutes to throw together as a proof of concept and still had 600m/s left in the tanks in a 100x100 orbit. I'm pretty sure you could make some very interesting chemical SSTO's with it. It's got potential. It also has a TWR of 1.6 on the pad which allows you to scoot out of the atmosphere pretty quickly.


[url]http://i.imgur.com/9PFLIAG.png[/url][/QUOTE]

Well, if you compare it with a spike (similar tech level), it is indeed a bit OP, but mostly it's a TWR thing, Isp is pretty much in line an in fact quite a bit lower. And TWR is only about 20% greater, per unit of mass. While I concur that it should be nerfed, perhaps not so much as everybody thinks... It's just that in SSTO applications, TWR has a greater influence than you might think. Give it ~800kN of thrust, and it would fit nicely in the engine curve.

In fact, I have been toying with an enlarged version of the Luster (mostly so I could actually use the thing without stranding half the flights due to the razor-thin margins). I used a few of the things you guys showed me here as inspiration, but I kept the spikes and in fact added Thuds to complement them and provide the gimbal: I know it would be more efficient using a single Vector, but what the hell, this looks better and I can put a Sr. docking port on the tail.

[img]http://i.imgur.com/ftQWIn8.png[/img]


Rune. It would be a "Lackluster meets Heinlein" kind of thing.