The K Prize - 100% reusable spaceplane to orbit and back

[Tiron]

Aaaand here we are again. More or less. Only this time I went straight to 500km, didn't reserve any fuel or burn off any oxidizer...which could make actually landing a bit tricky...but at least I'll be able to get within the right area.

Here we are doing a deorbit burn, with some help from the RCS to save fuel.

Finished, having used the last of the monopropellant to send it a bit short (the lift from the wings will make it go long), and it's actually not as short as I'd like. I've been left with only 20.78 units of fuel to land with. Eeesh. Guess I can't overshoot...or come up way short. This should be...fun.

Well, I forgot to take any screenshots on the way down, but other than some fire and some minor tumbling there wasn't much to see anyway. Here's after I got it stabilized and aimed at the KSC, with just the center engine going (to save fuel), angle because of flags (but the landing AP is up so you can read the distance, note I'm using the ILS guidance but NOT the landing AP, I don't trust that bloody landing AP):

Here we are, having come to rest on the runway. A little long (the ILS was bringing me in WAY steeper than 3 degrees so I ignored it and went long), but on the runway.

Flight log, just to show there's no decouplings and that yes, it is the same flight that just went to 500km.

Now if I could just get the bloody spaceport to let me log in...

Edit: And for the record, I don't trust Mechjeb's spaceplane landing AP for two reasons: First, it doesn't control throttle, only attitude, so its ability to put you where it wants to is limited. Second, because one time when I was first getting into planes and WAS using it, I bounced, and Mechjeb's AP turned the thing around completely backwards to try to get back to its 'landing point', resulting in the plane coming down backwards at an angle and ending up in pieces scattered across the runway. I'll just manual it, kthx.

Edited June 16, 2013 by Tiron

[pa1983]

I would suggest more intakes that way you can fly fast and high. Also two airospikes is overkill for that craft. I even think two jets will be more then enough if you get more intakes it will go fast and high. That also means less oxidizer is needed. If that works I would swap the airospike for a nuke instead.

Place the airospike in the center and use two jets. If it can climb at 45 degree angle its fine. Also lift is important. That saves the number of engines you need to get up to altitude and at high altitude there you go fast becuse of very little drag, lots of wings or not, many engines or not.

[Tiron]

I would suggest more intakes that way you can fly fast and high. Also two airospikes is overkill for that craft. I even think two jets will be more then enough if you get more intakes it will go fast and high. That also means less oxidizer is needed. If that works I would swap the airospike for a nuke instead.

Place the airospike in the center and use two jets. If it can climb at 45 degree angle its fine. Also lift is important. That saves the number of engines you need to get up to altitude and at high altitude there you go fast becuse of very little drag, lots of wings or not, many engines or not.

Oh I know. The smaller, Jet-only version (the -D) only has two engines, and the original version of this did too, but it was too sluggish so I stuck a third on. I can't figure out anywhere else to put more intakes that doesn't look like crap, and I *do* care how it looks, other than putting a couple of outboard tanks on...which is what the -G does. It also carries more fuel which mostly negates its ability to go higher and faster.

Putting an aerospike on the center might work, but breaks the fuel segregation, opening the possibility of the Turbojets eating liquidfuel meant for the rockets. Unless the entire thing is rebuilt with LFO fuel tanks in the center instead of jet-fuel-only tanks. But that'd be a COMPLETE rebuild, and it'd be a Ravenspear Derived something-Else. You don't need to rebuild it you can cross-route the fuel, but with ALL the engines mounted on the wrong tanks that makes the fuel routing distinctly tricky. You'd basically have to to use strict tank lockouts (to prevent the turbojets leaving you with an excess of oxidizer), and only use one engine type at a time (or you'll confuse the fuel flow logic).

Trust me, I've thought of all that, I just can't think of any way to really make it work well without basically using a completely different design. And the existing one already gets 1000 delta-V to orbit, and has jet fuel to spare.

If there were some way to block fuel crossflow to the engines and force them to use fuel lines, it could work. But I've already got another (rocket) design that's stuck because of that very problem. Why the heck did they suddenly decide to make EVERYTHING crossfeed?!

Edit:

There's also the Uprated -G Version that carries more fuel, and has capability to carry a rover. It's been to DUNA without refueling, but would have to refuel to get back.

I've posted a few shots of it before, but here's a SPH Shot of the current, rover carrying GR variant:

Edit2:

Just for fun, I tried swapping the Aerospikes for LV-Ns. Couldn't make orbit. Yeaaaah.

Edited June 17, 2013 by Tiron

[pa1983]

You can. But you need at least 1900m/s. 2100m/s or more in orbit with jets is preferd at 40km+ then the drag is so low you could easily put that in orbit with nukes. I run jets and nukes at the same time to at low throtel setting to get the most out of the fuel,

[Kappa73]

All righty, here is another try at the K-Prize.

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e: imgur tags

Edited June 17, 2013 by Kappa73
realized the imgur tags

[Tiron]

You can. But you need at least 1900m/s. 2100m/s or more in orbit with jets is preferd at 40km+ then the drag is so low you could easily put that in orbit with nukes. I run jets and nukes at the same time to at low throtel setting to get the most out of the fuel,

Low throttle setting doesn't help fuel efficiency on rockets.

And you can't achieve that kind of speed with a Jet without being either fairly lightweight (-D pure jet version got up to 1816 m/s on its test flight...but only after having burned off most of its fuel) or having your entire front end made out of intakes.

Which isn't what I'm looking for. The -F as it is now is both extremely reliable and very easy to fly, and I'm quite happy with it. Even if it's not the most efficient design ever.

The -G is NOT easy to fly, the extra weight changing its flight characteristics so much that it has to be manually nannied all the way up, and barely has enough jet fuel to get up to speed and altitude before firing the rockets. Unlike the -F, which has to cruise for several minutes once it gets there to burn off the excess fuel.

[pa1983]

Low throttle setting doesn't help fuel efficiency on rockets.

And you can't achieve that kind of speed with a Jet without being either fairly lightweight (-D pure jet version got up to 1816 m/s on its test flight...but only after having burned off most of its fuel) or having your entire front end made out of intakes.

Which isn't what I'm looking for. The -F as it is now is both extremely reliable and very easy to fly, and I'm quite happy with it. Even if it's not the most efficient design ever.

The -G is NOT easy to fly, the extra weight changing its flight characteristics so much that it has to be manually nannied all the way up, and barely has enough jet fuel to get up to speed and altitude before firing the rockets. Unlike the -F, which has to cruise for several minutes once it gets there to burn off the excess fuel.

Yes you can IF you use JETS to. Jets + rocket engines at low throttle means you can use the jets for longer with out flame out so yes it makes a WORLD off difference. I can half my oxidizer use that way.

My SSTO's tops over 213 tons at take off so I would say 600L of oxidizer to 100km LKO is efficient use of throttling instead of 1000L+.

[Tiron]

Yes you can IF you use JETS to. Jets + rocket engines at low throttle means you can use the jets for longer with out flame out so yes it makes a WORLD off difference. I can half my oxidizer use that way.

My SSTO's tops over 213 tons at take off so I would say 600L of oxidizer to 100km LKO is efficient use of throttling instead of 1000L+.

As I said, if efficiency is what you want. I'll take reliability and ease of use, thanks. And not looking like it's made of nothing but intakes.

[zekes]

Yes you can IF you use JETS to. Jets + rocket engines at low throttle means you can use the jets for longer with out flame out so yes it makes a WORLD off difference. I can half my oxidizer use that way.

My SSTO's tops over 213 tons at take off so I would say 600L of oxidizer to 100km LKO is efficient use of throttling instead of 1000L+.

Woah! My biggest SSTO is 80 tons! that's big!

[Tiron]

Woah! My biggest SSTO is 80 tons! that's big!

Yeah, I don't think I'd build one that big personally...eeeeesh. He might only be using 600L of Oxidizer but he's probably using at least 3000L of liquidfuel.

[pa1983]

3000L is pretty much right but thats nothing with 200+ tons with 45 ton of payload going to duna.

I can get a ssto with kerbals up in lko with 1/3 of the fuel so if I wanted I could land and take off again.

Reliability? I have not had a single reliability problem with my design and its easier to fly then more traditional designs. Most people cant maintain cg or get the drag fare back enough to make it stable.

Good ssto sould maintain cg at all times, easily done with parallel tanks only.

Lots of lift, easy to get with a flying body. Reduces the need for lots of engines and fuel. Wings have almost no drag sense drag is proportional to mass so they give high rate off climb with out introducing much drag at high speed and altitude.

Intakes should be behind cg to maintain stability. Common fault for instability when reentering.

Lots of intakes. Intakes are fubar in the game any way. Real problem is not the amount of air for a real craft but geting the air speed down to sub sonic speeds and secondly is that past mach 3 the air gets to hot for most jet designes. At mach 5.5 the air hits a 1000C entering a jet engine. Theres no jet engine that can take this. A heat exchanger is needed. Saber engine design will have one. The part exist in ksp but do not work.

So untill intakes are made realistic so we dont need a ton of them but rater a heat exchanger for high speeds intake abuse is the most efficient way and gets one closer to the real speed of tomorrows real space planes.

But if you dont like good advice thats fine, you dont seem to take advice very well any way.

Btw jets have in practice about 20k isp in ksp due to the fact that thy get there oxidizer from the air so its not 1200 or 2000, its a lot more. Rockets have nothing that comes close. So its fare more efficient throttling down to avoid flame out and use rockets to maintain accalaration and climb then using just rocket power.

But you will figure that out in time and much more.

But Im not going to give you any more advice sense you dont seem to like that.

Some one else migth find it useful.

Edited June 18, 2013 by pa1983

[Tiron]

But if you dont like good advice thats fine, you dont seem to take advice very well any way.

Because it's not a 'I need help getting my SSTO to work' thread, or a 'I need help making my SSTO better', thread, it's a 'Show off your SSTO' thread.

I didn't *ask* for advice, and frankly most of the advice you give is condescending and belittling. I spent literally weeks getting that bloody thing to work(if you count the numerous failed prior attempts), and the first thing you post about it boils down to 'that's a piece of crap, you should do this instead.'

Some of us *like* doing things for ourselves.

[pa1983]

I offered some friendly suggestions and tips . You where condescending by telling me I am wrong when I know other wise from experience and assuming things about my design in a condescending manner to other other members is rude so dont tell me it was not fair for me to give a proper reply.

I usually dont give advice if I dont see potential in the design and its maker but you didnt seem to see that just some negative crap.

Edited June 18, 2013 by pa1983

[zekes]

I offered some friendly suggestions and tips . You where condescending by telling me I am wrong when I know other wise from experience and assuming things about my design in a condescending manner to other other members is rude so dont tell me it was not fair for me to give a proper reply.

I usually dont give advice if I dont see potential in the design and its maker but you didnt seem to see that just some negative crap.

Considering pa has the largest, most efficient SSTO here, I'd treat him like a god

[pa1983]

Im no god I just practiced a lot. I saw someone doing something I did only a few months ago so I got nostalgic because I could see what is to come. My first post was actually a compliment, not a clear one maybe but still. I shall use the rep button next time and do a combo

I hope we can put this misunderstanding behind us and if some one dont like my tips there free to ignore them.

[zekes]

Im no god I just practiced a lot. I saw someone doing something I did only a few months ago so I got nostalgic because I could see what is to come. My first post was actually a compliment, not a clear one maybe but still. I shall use the rep button next time and do a combo

I hope we can put this misunderstanding behind us and if some one dont like my tips there free to ignore them.

dude. your SSTO is 1200 parts. Either your patience or your computer are a miracle.

[pa1983]

That just one off many. I got a small one, old but its still none stop to laythe and back. 5 jets and two nukes.

Then I got all sizes in between.

Btw it runs fine with 1300 parts on a i7 3770 with the hd4000 gpu on low settings with smooth frame rates. Sure not realtime but I never get that on kerbin ithere its windows 7 with a i7 3770 or linux with a i7 3930k and gtx570 even with just 80 parts. So 80 parts or 800 parts makes no difference to me.

1200 is pushing it but another tip is not to focus on parts but what parts are used. Engines are a lot more demanding on physics and frame rate then say intakes or the 1kg girders. I have a max budget of 14 jet engines and thats because 1200 part space plane with 14 jets runs at 30-40 fps while a 1000 part one with 20 runs a 4-5 fps. Not all parts are equally demanding. Few engines but lots of wings runs faster then lots off engines and less wings.

I5 2500k should run it fin with a modest gpu.

But yea most of my sstos are large but thats becuse the challange to improve and achive a goal like payload delivery is hard and not easy to do with few parts with out mods atm. I hope for more arospace parts in the future so we can get part count down.

Edit: it would be nice to know how demanding different parts are. I try to avoid using many engines and pods. Those seems to have the most negative effect. Wings seems mediocre and girders, at least the 1kg seems to have little effect on realtime and fps.

Edited June 18, 2013 by pa1983

[pinolallo]

I agree with pa1983, his advices are from an experienced ssto builder and I find it's design valid AND unbelievable successful, others are just chit chats.

But:

In a straight stock point of view build such a ssto will need thousands of parts and this, for an exponential physics algo part based, is really too much.

For this reason I stopped to make computer killer ships using such an insane number of parts.

I do prefer use the procedural wings or the b9 large wings and the b9 airintakes (against a block of norma ramintakes. So my lates 40+ tons lifter has just 170 parts and just 8 structs.

Conceptually I think that use an SSTO is good to lift things in orbit, not to bring that things around the kerbol system that is good for a challenge not for a planned colonize program. I do lift in orbit SSTO using a SST0. For example i dropped the Münliner (that fly in a single jump to mün and back) for a better designed system: I do bring in orbit an extra atmospherical SSTO shuttle using the lifter, and bring that back to KSC using the same SSTO lifter: better result with minor effort.

So the main idea to bring things in duna can be:

a) lift your payload to LKO space station

ferry your payload from LKO spacestation to LDO (Duna Low Orbit) spacestation using a extra atmospherical shuttle.

c) drop your stuff to Duna surface using a Duna SSTO from the Duna spacestation.

Yes, you will have 4 different ships (kerbin SSTO, SpaceStation, EA Shutte an Duna SSTO) to ferry the payload, but that ships can be optimized for the task. So the Kerbin SSTO will be different from the Duna SSTO and the interplanetary shuttle designed to never land on a planet but very effective to transport.

Edited June 18, 2013 by pinolallo

[Psycho529]

I did have a fairly nice design but it's a VTOL so I can;t really put it up here after reading rule 2...

[Psycho529]

Just made an SSTO that only just made it to the Mun... then ran out of fuel

http://imgur.com/a/QLzUs

[Psycho529]

Modified that SSTO and made it to the Mun . But blew it up in an attempt to take off from the Mun...

http://imgur.com/a/QLzUs

Edited June 18, 2013 by Psycho529

[Jod]

I can get a ssto with kerbals up in lko with 1/3 of the fuel

How do you exactly save that much? Because I get flame-outs at 27 000m altitude no matter what I do: decreasing engine throttle, adding MOAR intakes, increasing number of turbojets up to 20...

I am working on a 200 ton SSTO too btw, able to carry a payload of 40 tons. Gets to orbit burning two orange fuel tanks almost to 0. Consists of only 400 parts though, anything more than that starts to lag badly.

I am impatient though, if your method is waiting for 10+ minutes while the weak-ass jets accelerate the damn thing then I would prefer assembling more efficient interplanetary craft in orbit.

[pa1983]

I agree with pa1983, his advices are from an experienced ssto builder and I find it's design valid AND unbelievable successful, others are just chit chats.

But:

In a straight stock point of view build such a ssto will need thousands of parts and this, for an exponential physics algo part based, is really too much.

For this reason I stopped to make computer killer ships using such an insane number of parts.

I do prefer use the procedural wings or the b9 large wings and the b9 airintakes (against a block of norma ramintakes. So my lates 40+ tons lifter has just 170 parts and just 8 structs.

Conceptually I think that use an SSTO is good to lift things in orbit, not to bring that things around the kerbol system that is good for a challenge not for a planned colonize program. I do lift in orbit SSTO using a SST0. For example i dropped the Münliner (that fly in a single jump to mün and back) for a better designed system: I do bring in orbit an extra atmospherical SSTO shuttle using the lifter, and bring that back to KSC using the same SSTO lifter: better result with minor effort.

So the main idea to bring things in duna can be:

a) lift your payload to LKO space station

ferry your payload from LKO spacestation to LDO (Duna Low Orbit) spacestation using a extra atmospherical shuttle.

c) drop your stuff to Duna surface using a Duna SSTO from the Duna spacestation.

Yes, you will have 4 different ships (kerbin SSTO, SpaceStation, EA Shutte an Duna SSTO) to ferry the payload, but that ships can be optimized for the task. So the Kerbin SSTO will be different from the Duna SSTO and the interplanetary shuttle designed to never land on a planet but very effective to transport.

I completely agree. I have been working on a SSTO that have space for a booster stage to and a jumbo tank at least. IRL it would be to costly to send an SSTO on a 3 year mission sens it at the most would do 10 missions in it life time if there is a fast turn around. But it gets routine to manage a single craft so I find it relabel from a gaming perspective and also the challenge to build the craft. Plus you have good precision so you can land spot on and also the payload requires little to no modification to fit. No need for lander stage etc. Also saves space in the SSTO. So theres plus and minuses but in KSP time realy dont mater atm. For career mode LKO missions makes the most sense. I have not tried it but in theory one could lift a payload from another planet to if needed.

How do you exactly save that much? Because I get flame-outs at 27 000m altitude no matter what I do: decreasing engine throttle, adding MOAR intakes, increasing number of turbojets up to 20...

I am working on a 200 ton SSTO too btw, able to carry a payload of 40 tons. Gets to orbit burning two orange fuel tanks almost to 0. Consists of only 400 parts though, anything more than that starts to lag badly.

I am impatient though, if your method is waiting for 10+ minutes while the weak-ass jets accelerate the damn thing then I would prefer assembling more efficient interplanetary craft in orbit.

I cut engines of in pairs so I run on two engines the last bit then I have 10 intakes per engine but its a bit overkill sens the gains drop off then I throttle down to. I also find that mounting the jets on 1kg girders on the big girders or I beams seems to reduce the flame out threshold even down ti 0.01. Do not seem to work as soon as one engine is mounted to a fuel tank, maybe not even rocket engines because it wont work on my Jumbo atm but did at least on older crafts in 0.18. But I also run until I get fluctuations on the intakes sens a big SSTO wont spin out of control if you press the key as soon as it indicates insufficient air on the resource bar plus I have LOTS of rudder control. Thats an important feature for stability. My crafts cant fly with out it at all because there more or less pure delta wing design. I have run engines at up to 56Km I think but that is at 2Kn or so trust but enough to often maintain the orbit while its doing the suborbital jump so to speak where there still is drag.

Also if possible mount the last jet in the center. And run the last jets and rockets at the same time that saves fuel sens jets are more efficient.

When I started to fly my jumbo I used like 1500L of oxidizer for LKO. Now Im down to 600L so practice saves fuel.

I have achieved over 2100 delta V with jets alone so with nukes even close to 200 tons wont take much oxidizer. That was with two jet engines the last way to but it tends to slow down a bit before I got rockets.

Speed is also important to get air intake. I write down flame out numbers and also a diagram where I do changes in angle as I climb. Climb to fast and you wont get enough speed and actually drop again. Climb to slow and you burn to much fuel. I dont use mechjeb so took me a howl day of try and error to get a useful preliminary chart for my Jumbo. But once one gets more confortable I have a chart with more or less exact flame out numbers so I cant be ready to hit the action key asap.

Edited June 18, 2013 by pa1983

[kepicness]

Would you mind posting an image of that chart? I'm really interested in your results.

[numerobis]

You could calculate your flameout ahead of time, rather than doing experiments.

I also find it useful to close intakes at low altitude so you can build up speed a bit better -- between about 1 and 15 km, a single intake can power two turbojets, up to nearly four at 5 km altitude. Any more intakes is just adding drag, so close them until you get higher.