Rolling Stone - science SSTO with unlimited range

[Mesklin]

Ladies and gentlemen, let me introduce new generation of science ships "Rolling stone" - SSTO with unlimited range of flights. You may ask, how is it possibly? And I have simple answer: ISRU converter and ore drills on board that marvel of engineering. This craft can ascent from sweet Kerbin to dark and harsh space with no left behind and reach any body in Kerbol system, then land on it for researching and refueling (except Tylo and Eve only). And later repeat it so many times as you wish. Ship has on board perfectly equipped mobile lab with full set of science instruments and comfortable crew apartments for 6 brave kerbals (2 pilots, 2 engineers and, of course, 2 scientists).

Brief tech stats:

Fully fueled mass (on launchpad) - 142t (140 parts)

maximum dV after refueling - ~5400 m/s (with 440 units of oxidizer on board and ore conversion to fuel in flight)

Horizontal landing on atmospheric planets and vertical landing on atmospheric less bodies. Horizontal takeoff.

Engines: 4 turbojets, 4 RAPIERs and 4 LV-N "Nerva"

Full set of science equipment

Full set of ISRU equipment

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Flight profile is next (almost standard for me):

1. After take off set pith to 25-30 and wait until you reach 10 km (speed at this tine should be 260-270 m/s);

2. Set SAS to prograde and wait until 5 degrees of pith, set SAS back to stability assist, relax and watch fire show until you reach ~20 km of altitude;

3. When speed stopped to increase (speed should be >1200 m/c at this moment) on nukes (press 1);

4. When speed stopped to increase again switch RAPIERs to vacuum mode (press2) and set pith to 20, several seconds late turbojets will be stopped without air (you can hear this moment very exactly), off turbojets by press 3;

5. Maintain pith about 20 until RAPIERs stay online, then off it (press 4), set SAS to prograde mode and wait to desired apoapsis, in apoapsis make circularization burn.

Edited July 14, 2015 by Mesklin

[Rune]

That is awesome. And pretty light, for what it does? Are you sure the powerplant is the most efficient, tough? From what we have tinkered away in the single turbojet challenge, RAPIERs get much higher cutoff velocities... can't it break Mach on, say, six RAPIERs and two turbojets?

Rune. I ask because at some point, I am making one of these.

[Mesklin]

Rune, maximum efficiency of atmospheric engines is not so important for this craft. It is not a big deal: achieve you Kerbin or Laythe orbit with dV 2700 m/s or with 2400 m/s on board (in any case, it is enough for reach the nearest atmosphere less body for refueling). Here is more important total vacuum dV with minimal quantity of oxidizer and in this situation turbojets are lighter and also make more comfortable and fast ascent.

For break Mach barrier I am using "dive" technique: climb to 10 km with 25-30 degrees of pith, then down nose to 5 degrees above horizon and see miracle of turbo bust.

[SHiftER2O]

I've seen this somewhere in the WIP before, glad it's finally out

And if you don't mind, I'm taking this in as a... sample for studies

[trash0551]

This thing is a beast. Well done! Just curious, what's your ascent profile like on Kerbin? I can make orbit but only with about 2k m/s left in the nukes.

[Rune]

This thing is a beast. Well done! Just curious, what's your ascent profile like on Kerbin? I can make orbit but only with about 2k m/s left in the nukes.

That is way more than enough to go to Minmus to top off the tanks. Hell, even Mun is doable with that kind of delta-v.

Rune. But Minmus is easier.

[trash0551]

That is way more than enough to go to Minmus to top off the tanks. Hell, even Mun is doable with that kind of delta-v.

Rune. But Minmus is easier.

Oh I know Just the OP mentioned 2400-2700m/s in his post, so I was curious how his ascent differed from mine. I went to 10.5km at ~28 degree pitch, pitched down to ~8 degrees to nearly stop vertical climb and build horizontal speed. When I thought unplanned rapid disassembly was nearing due to the heat (I was going about 800-900m/s horizontal), I slowly pitched back up to ~45 degrees to push AP to ~80km and circularized from there.

I guess the problem I had is my rapiers flamed out at about ~23km and turbos a few km later. I didn't run the nukes until this point and had to kick rapiers to closed cycle sooner than it seemed like I should. This meant they ran out of fuel before AP and I had to use the locked fuel for a little extra boost.

[trash0551]

Ok, with a bit smarter profile I reached 75km with 2409m/s delta-v left in the nukes. And I didn't have to tap into the hidden oxidizer for the rapiers. In fact, was able to reach orbit with 165 oxidizer left in the main tanks.

I think the biggest change was continuing to build horizontal speed until over ~1200m/s (at about 22-23km). From here, I made a gentler climb (~20 degree AoA) and the turbos flamed out before the rapiers. Kicked the nukes on and ran the rapiers in airbreathing until they were less than 40kN of thrust. Closed the intakes, switched to close cycle, pushed AoA to ~30 until altitude was above ~42km and time to AP was ~1 minute. From here I turned off the rapiers and just ran on nukes, occasionally kicking rapiers on to keep AP 1 minute out. At close to 60km, I held just above prograde until 75km AP reached and finished with a circularizing 70m/s burn.

I'm not the best pilot so there's probably things that make you go "huh?" But I'd still be curious how the OP did it

[Guerra]

Did you happen to get the name of the craft from the ship in Robert A. Heinlein's book, The Rolling Stones?

[Kagame]

This is something I had been contemplating for a while, but you actually went and made it. Nice. Pretty cool how you managed to get the engine count so low.

[Rune]

Oh I know Just the OP mentioned 2400-2700m/s in his post, so I was curious how his ascent differed from mine. I went to 10.5km at ~28 degree pitch, pitched down to ~8 degrees to nearly stop vertical climb and build horizontal speed. When I thought unplanned rapid disassembly was nearing due to the heat (I was going about 800-900m/s horizontal), I slowly pitched back up to ~45 degrees to push AP to ~80km and circularized from there.

I guess the problem I had is my rapiers flamed out at about ~23km and turbos a few km later. I didn't run the nukes until this point and had to kick rapiers to closed cycle sooner than it seemed like I should. This meant they ran out of fuel before AP and I had to use the locked fuel for a little extra boost.

Ok, it seems you know your stuff. I may have to fly this and see how much I can get out of it! It would be informative to measure my flying skills against Mesklin's considering I often look at his designs as a source of inspiration. The guys squeezes stock parts to places I didn't know they cold get to! In fact, this very thread gave me something to do today:

I'm kind of stuck at ~1,500m/s on orbit with very low TWR already, but then again, that is enough for the initial hop to Minmus, and I managed to cut the powerplant in half (obviously I also didn't put any sciency stuff in). But I like out sleek it turned out, and how I managed to tuck all the sensor stuff inside the bay. The sat may seem a bit of a tight fit, but thankfully that big dish appears to have a very small collision mesh, docking it back is really easy.

BTW, @Mesklin, I imagine the longest leg of the trip was the Gilly-Moho leg... how much dV did that take you? So I have a target to shoot for.

Rune. Might go bigger with another one!

Edited June 14, 2015 by Rune

[Mesklin]

Did you happen to get the name of the craft from the ship in Robert A. Heinlein's book, The Rolling Stones?

You are right, name for craft was inspired by this Robert A. Heinlein's book. I am very like Heinlein's books

Sorry for delay gentlemen, I was out of internet access for several days. Flight profile is next (almost standard for me):

1. After take off set pith to 25-30 and wait until you reach 10 km (speed at this tine should be 260-270 m/s);

2. Set SAS to prograde and wait until 5 degrees of pith, set SAS back to stability assist, relax and watch fire show until you reach ~20 km of altitude;

3. When speed stopped to increase (speed should be >1200 m/c at this moment) on nukes (press 1);

4. When speed stopped to increase again switch RAPIERs to vacuum mode (press2) and set pith to 20, several seconds late turbojets will be stopped without air (you can hear this moment very exactly), off turbojets by press 3;

5. Maintain pith about 20 until RAPIERs stay online, then off it (press 4), set SAS to prograde mode and wait to desired apoapsis, in apoapsis make circularization burn.

Also you can watch video example of ascent

.

- - - Updated - - -

BTW, @Mesklin, I imagine the longest leg of the trip was the Gilly-Moho leg... how much dV did that take you? So I have a target to shoot for.

Very interesting craft, Rune, really neat design. And for Gilly-Moho travel: for this trip you can spend only about 3 km/s dV for reach Moho orbit (in my first attempt with previous design of ship), I was to relaxed in second attempt and it was very nervous landing (only third try was successfully). Start trip in periapsis Eve orbit to perapsis Moho orbit in orbits node, set periapsis of departure ellipse close as possibly to Eve atmosphere, match inclination of orbits when you make first deceleration burn.

Departure maneuver (only 1056 m/s)

After leaving Eve's SOI, inclination to Moho orbit is only 0.3 degrees

Final math inclination

Burn on solar orbit for meeting with Moho (after several rounds around Kerbol)

Moho's circular orbit reached

[Tangle]

Am I super messing things up, or was I following the ascent thing wrong? I did the instructions, but at 10 km I can't go down to 5 degrees of pitch or I start falling.

[SHiftER2O]

Am I super messing things up, or was I following the ascent thing wrong? I did the instructions, but at 10 km I can't go down to 5 degrees of pitch or I start falling.

I actually am in par with you, my friend.

I swore I made it work before....

[Mesklin]

Am I super messing things up, or was I following the ascent thing wrong? I did the instructions, but at 10 km I can't go down to 5 degrees of pitch or I start falling.

When you switch SAS to prograde at 10 km (important action) and then set back to stability assist at pith 5 craft will start losing altitude a bit, it is normal, do not worry (vertical speed should not exceed -10 m/s). After several tens second craft will start to rise altitude again. Also see video for help in flight instruction spoiler (I added it on the first page).

[Rune]

Very interesting craft, Rune, really neat design. And for Gilly-Moho travel: for this trip you can spend only about 3 km/s dV for reach Moho orbit (in my first attempt with previous design of ship), I was to relaxed in second attempt and it was very nervous landing (only third try was successfully). Start trip in periapsis Eve orbit to perapsis Moho orbit in orbits node, set periapsis of departure ellipse close as possibly to Eve atmosphere, match inclination of orbits when you make first deceleration burn.

Departure maneuver (only 1056 m/s)

http://i.imgur.com/FnBL7I9.png

After leaving Eve's SOI, inclination to Moho orbit is only 0.3 degrees

http://i.imgur.com/FX0wGQw.png

Final math inclination

http://i.imgur.com/303nlwO.png

Burn on solar orbit for meeting with Moho (after several rounds around Kerbol)

http://i.imgur.com/tVCt1DF.png

Moho's circular orbit reached

http://i.imgur.com/FSuBEyX.png

Thanks! That will be very helpful to know... just to clarify, 3km/s to orbital insertion, or 3km/s with the landing included? Because you don't show the maneuver for Moho orbit insertion, and that is the one I fear the most! In any case, thanks again for the careful explanation, I know those things take time, and I found it very helpful! (I'd give you more rep, but you know how that goes)

Rune. If 3km/s are enough, then that bird I showed can do it on a pure liquid fuel mix!

[Mesklin]

3 km/s to orbital insertion + 1.2 km/s for landing with low TWR

Picture with orbital insertion burn, it was my minimal burn for Moho insertion in my space carier

[Rune]

3 km/s to orbital insertion + 1.2 km/s for landing with low TWR

Picture with orbital insertion burn, it was my minimal burn for Moho insertion in my space carier

http://i.imgur.com/MDfqQZG.png

Well boop. I kind of expected that. Anyhow, now I know: about 4.5km/s in the tanks when fully refueled at Minmus, and you can call yourself able of doing a Grand Tour as long as you do things carefully, with some margin. (Note: when I add up all those burns, I get closer to 2.5km/s+landing, and you show at least one inclination change that's not really required, but I'll call that further margin on the margin, I am a fan of those ).

Rune. I'm going to have to go all Mk3 on this problem, it seems. To the SPH! Turns out I had some tanks empty, Kod knows why, and it already can do 4.252m/s if I load her right!

Edited June 15, 2015 by Rune

[Mister Dilsby]

Really impressive, puts my poor little Hummlebee to shame. I'll have to try something like this once I get RAPIER in career, or maybe work on an all-LF version (TRJ+LVN).

[Fearless Son]

Wow, this is one of the better designs I have seen! I am especially impressed that you managed to get so much functionality and aesthetic with such a (relatively) low part count.

[Roflcopterkklol]

Hmm how did you manage to get into orbit with so few engines? im already at nearly double your crafts mass trying to make a similar design and to get it into orbit im using 10 rapiers and 20 turbo jets, admitted its TWR is over 2:1, ill try lowering the twr and see how it goes i guess. Your a legend OP, i did not even think of building a craft like this before you did.

Edited June 21, 2015 by Roflcopterkklol

[Rune]

Hmm how did you manage to get into orbit with so few engines? im already at nearly double your crafts mass trying to make a similar design and to get it into orbit im using 10 rapiers and 20 turbo jets, admitted its TWR is over 2:1

There's your problem (emphasis mine). Rocketry is all about ratios, not raw engine numbers, and a low thrust to weight ratio allows you a high fuel fraction. And in rocketry, fuel fraction is king (as long as you have enough oomph to lift up, of course). You will never match the efficiency on low TWR designs with high TWR designs, no matter how many engines you slap on.

Rune. Because physics and math.

[Roflcopterkklol]

There's your problem (emphasis mine). Rocketry is all about ratios, not raw engine numbers, and a low thrust to weight ratio allows you a high fuel fraction. And in rocketry, fuel fraction is king (as long as you have enough oomph to lift up, of course). You will never match the efficiency on low TWR designs with high TWR designs, no matter how many engines you slap on.

Rune. Because physics and math.

Idk my high twr craft seem to out perform my low twr craft constantly, Cronus is a good example of that, i was unable to get 80 tons into orbit without a TWR of 1.8:1, Maybe its just the way i build things... im terrible at being conservative.

[trash0551]

Idk my high twr craft seem to out perform my low twr craft constantly, Cronus is a good example of that, i was unable to get 80 tons into orbit without a TWR of 1.8:1, Maybe its just the way i build things... im terrible at being conservative.

http://i.imgur.com/ksPICP9.jpg

I might be wrong here but I think the idea with spaceplanes is you don't need a TWR over 1 necessarily. Its not a rocket, its a plane. It has wings. Wings provide lift. At least that's my understanding.

I believe the OP's plane has a TWR of 0.9 on the runway.

[Rune]

I might be wrong here but I think the idea with spaceplanes is you don't need a TWR over 1 necessarily. Its not a rocket, its a plane. It has wings. Wings provide lift. At least that's my understanding.

I believe the OP's plane has a TWR of 0.9 on the runway.

Yup. The Mach barrier puts a lower bound on that (grrr), but with about 0.9-1.0 on the runway, you can break it at ~10kms going a bit shallower than usual, as long as your plane is not too draggy. And then all the weight you save in engines can be fuel to increase you vacuum dV and payload.

Rune. TWR does marginally increase the atmospheric cutoff speed, but then again, it's not really worth it.