An Affordable Space Program: making the reusable spacecraft pay off.

[SirJoab]

Great challenge SirJoab, let's see if you can get more entrants now that you've been stickied

Awesome!

[Darnok]

* No solid fuel boosters, as they cannot be refueled.

If I design and screen how I recover and attach boosters to the rocket can we pretend they can be refueled?

[SirJoab]

If I design and screen how I recover and attach boosters to the rocket can we pretend they can be refueled?

Hmm... I'm interested. Would you mind making a small demonstration? One question though, why not just make liquid-fuel boosters to do the job?

[Darnok]

Hmm... I'm interested. Would you mind making a small demonstration? One question though, why not just make liquid-fuel boosters to do the job?

In next week, right now I have to calculate few things and find a way to connect rocket stages, if that is even possible without decouplers.

Main idea is shown here (I am not doing Ares rockets, just taking inspiration from it)

Ares I stage 1 is used as booster in Ares V.

Ares I stage 2 is used as stage 2 in Ares V lite.

Ares V and Ares V lite stage 1 is designed for heavy payloads, from my initial tests with new parts it should go ~45 tons without stacking fuel and engines in clusters.

Still have to design Ares V stage 2 and Ares I first stage.

[LordFjord]

The question is: how do you want to decouple and recover the boosters with the limitation that the KSP engine deletes objects beyond ~2.5km distance within the atmosphere (or at least to a certain altitude)?

I am also pondering to create a 2nd entry - probably some bigger plane-like SSTO attempt. You know, gotta try and test the new parts

The CLAW also offers new reload/refuel mechanisms.

I mean why dock the payload when you can grab it?

[Darnok]

The question is: how do you want to decouple and recover the boosters with the limitation that the KSP engine deletes objects beyond ~2.5km distance within the atmosphere (or at least to a certain altitude)?

That is not a problem, all you need is to attach remote command unit to for example booster and you have new vehicle that won't be deleted

I am also pondering to create a 2nd entry - probably some bigger plane-like SSTO attempt. You know, gotta try and test the new parts

The CLAW also offers new reload/refuel mechanisms.

I mean why dock the payload when you can grab it?

Yea CLAW gave me new ideas. Well if I fail building rocket I will probably finish my SSTO Phoenix.

[LordFjord]

That is not a problem, all you need is to attach remote command unit to for example booster and you have new vehicle that won't be deleted

Are you sure with this? Probe core and even manned separated vessels disappear after said distance. At least in 0.23.

My tests for a science bomber some month ago (para drop small probes with science gear on Kerbin) failed - all probes disappeared. When I switched to a probe after drop, the manned plane disappeared.

[Keldaria]

Hmm... I'm interested. Would you mind making a small demonstration? One question though, why not just make liquid-fuel boosters to do the job?

Just for purity sake, I'd recommend separate leader boards for people who need a VAB to reassemble their craft, otherwise its not really fair to those who designed craft that didn't need the VAB to reload payload (and/or fuel) to relaunch.

To be completely honest, its not hard to develop a reusable launch vehicle if all you need to do is recover the parts, just develop a 2 stage system with boosters that separate before you start your gravity turn and have parachutes that auto deploy on staging. I'd be curios to see any attempt mind you because I tend to draw inspiration from others but I just think using the VAB to reassemble recovered pieces, sort of defeats the purpose of this challenge in my mind.

A huge portion of this challenge has always been reloading/fueling the launch vehicle, so if you could for instance show me that you can reassemble and reload (payload) and refuel liquid propellants without entering the VAB, then I'd say it would probably be fair to allow the use of hyperedit or something to refuel solid boosters... but then again this isn't my challenge so take my opinion for what its worth (probably nothing lol).

Edited April 4, 2014 by Keldaria

[Rakaydos]

A huge portion of this challenge has always been reloading/fueling the launch vehicle, so if you could for instance show me that you can reassemble and reload (payload) and refuel liquid propellants without entering the VAB, then I'd say it would probably be fair to allow the use of hyperedit or something to refuel solid boosters... but then again this isn't my challenge so take my opinion for what its worth (probably nothing lol).

On the other hand, you spawn big fuel tanks to refuel your rocket, right? Spawn some spare SRBs at the same time, and manually attach them, and you dont need to recover them. SRBs are dirt cheap anyway, according to VAB prices...

[gchristopher]

On the other hand, you spawn big fuel tanks to refuel your rocket, right? Spawn some spare SRBs at the same time, and manually attach them, and you dont need to recover them. SRBs are dirt cheap anyway, according to VAB prices...

That doesn't sound right to me. If you attach SRBs that just fall into the ocean, that's not reuse. Those big refueling tanks never leave the ground as part of any launch system. The game just doesn't provide fuel trucks, so we have to make them.

I think the point of the challenge was pretty clearly to land and reuse absolutely every bit of mass that goes into ascent. Allowing spawning new disposable SRBs invites trivial abuses like having your launch vehicle just being a pod sitting on top of 100 boosters that are "reused."

I agree with Keldaria, hyperedit refueling of solid rocket boosters that somehow make it back to the launch pad sounds like a reasonable way to treat it as reusable, but it has to be the exact SAME booster that goes up each flight. That's the same restriction that applies to every engine, fuel tank, coupler and strut that comprise the rest of the vehicles.

[gchristopher]

You people that finished stations already are amazing. I'm close, but this is so HARD!

I don't know if it's all the docking and undocking, switching between vessels and the space center a million times, or the 23.5 update, or micro space gremlin krakens, but the reusable fleet is really starting to feel the effects of being in use for so many missions.

As you can see, parts have started to drift from their attachment points. When I switch to the combined vehicle in orbit, it immediately experiences phantom forces and slowly rolls to the left. SAS doesn't seem to notice. I'm glad that at least I stuck to all stock parts!

It's still flyable, but some of the thrust and lift vectors are a little bit off, so I can't go above 2/3 throttle on landing or else it gets confused and nosedives. Also, you have to gently roll right continually in flight to overcome the phantom roll effect.

Hang in there little spaceship, only two flights to go!

(Edit, I'm almost 100% sure there's never been a "structural failure" message, crash or contact with the ground. I'm pretty sure the vehicle damage is from updates or quirks with the physics engine or part tree rebuilds during docking. It's been through dozens of docking cycles.)

Edited April 5, 2014 by gchristopher

[Mecha Pants]

If I remember correctly, solid rocket boosters stay active even when empty, and hyperedit refueling immediately causes them to reignite/explode.

[SirJoab]

A huge portion of this challenge has always been reloading/fueling the launch vehicle, so if you could for instance show me that you can reassemble and reload (payload) and refuel liquid propellants without entering the VAB, then I'd say it would probably be fair to allow the use of hyperedit or something to refuel solid boosters... but then again this isn't my challenge so take my opinion for what its worth (probably nothing lol).

I completely agree. I would have to make a separate leaderboard for anyone using new boosters from the VAB or SPH as part of their refueling process. Hyperedit on the ground for the solid boosters would be more acceptable.

But... I'm going to wait and see what people come up with before setting this in stone. There are some pretty creative people around here.

[Mecha Pants]

Working on an entry of my own, but have run into a bit of a snag. I had planned to use the ARM claw as an extremely forgiving cargo hook for my spaceplane, but it seems for a fraction of a second physics turn off as it grabs. This makes my spaceplane and cargo loader/refueler clip through the runway and fall into the subsurface ocean. I'm going to have to do more experimentation to figure out a way past it.

[sdj64]

Wow gchristopher, that's quite a bit of machinery you've got there. The spaceplane that splits in half lands the center lifter back at KSC? It seems like just having parachutes would be simpler, but then again it's really cool how everyone comes up with their own unique solution.

I'm also working on an entry, currently trying to work out the problems before starting the space station for real. In my current design, the ship lands horizontally, accepts its payload on its nose, then pushes itself back to vertical for takeoff using a downward pointing engine in the front.

Currently its payload is limited by this step: anything that it can push into the vertical position, it can bring to orbit. Long payloads also are a problem: the solar boom in the picture could barely be lifted even though it weighs only a few tons. It can lift about 12 if the payload is short.

[Rakaydos]

That doesn't sound right to me. If you attach SRBs that just fall into the ocean, that's not reuse. Those big refueling tanks never leave the ground as part of any launch system. The game just doesn't provide fuel trucks, so we have to make them.

I think the point of the challenge was pretty clearly to land and reuse absolutely every bit of mass that goes into ascent. Allowing spawning new disposable SRBs invites trivial abuses like having your launch vehicle just being a pod sitting on top of 100 boosters that are "reused."

If you can reattach 100 solid boosters without recovering your craft, get back in the air, and not spin out of control from misaligned docking ports, I'd call that a win. It's an "abuse" that's far harder than simply pumping more fuel into your tanks.

[Keldaria]

If you can reattach 100 solid boosters without recovering your craft, get back in the air, and not spin out of control from misaligned docking ports, I'd call that a win. It's an "abuse" that's far harder than simply pumping more fuel into your tanks.

It's not really about that, it's more about staying true to the challenge of reusable spacecraft. Otherwise the challenge would be to assemble a craft outside the VAB. Nobody is denying that reassembly of a vehicle outside the VAB isn't hard but it can be abused, such as by creating a small control vehicle that is reusable and just reattached to payloads that contain the primary lift functions.

At the end of the day I think you should try whatever you think is appropriate for the challenge and let SirJoab determine how valid of a setup it is for the challenge. Something designed where you have to reattach a few freshly spawned SRB to your main craft may be perfectly fine, especially if you spawn them 1 at a time and use a single, none recovered vehicle to capture and move them to your rocket for attachment.

Also sdj64 that's awesome, I had thought about attempting a launch stage that lands horizontal and tilts back to vertical but I nixed the idea pretty fast because I could get the tilt function right with a detachable engine and I didn't want to carry the extra weight of the tilt engine back and forth to orbit. Also my designs never incorporate the payload into the tilt, that would have gotten attached after but that is an awesome solution because it would probably be easier to attach in a horizontal application. So kudos to you for making that work, it looks awesome.

[Rune]

You people that finished stations already are amazing. I'm close, but this is so HARD!

I don't know if it's all the docking and undocking, switching between vessels and the space center a million times, or the 23.5 update, or micro space gremlin krakens, but the reusable fleet is really starting to feel the effects of being in use for so many missions.

http://i.imgur.com/RoXI7W2.jpg

As you can see, parts have started to drift from their attachment points. When I switch to the combined vehicle in orbit, it immediately experiences phantom forces and slowly rolls to the left. SAS doesn't seem to notice. I'm glad that at least I stuck to all stock parts!

It's still flyable, but some of the thrust and lift vectors are a little bit off, so I can't go above 2/3 throttle on landing or else it gets confused and nosedives. Also, you have to gently roll right continually in flight to overcome the phantom roll effect.

Hang in there little spaceship, only two flights to go!

(Edit, I'm almost 100% sure there's never been a "structural failure" message, crash or contact with the ground. I'm pretty sure the vehicle damage is from updates or quirks with the physics engine or part tree rebuilds during docking. It's been through dozens of docking cycles.)

Hey! Your entry has been a true pleasure to follow, hang in there and get it done, we are all cheering for you! (even if your payload capacity is likely to put you over my scores ). Second, I also saw that bug, my fuel lines were touching the ground by the end, but were the only part affected. I think it's the slight "jump" the ships do when docking and aligning themselves without regards for physics: if something physics-less (like fuel lines or struts) was out of place before physics got annulled, it stays there when the other parts are re-loaded in neutral positions, and ends up completely wrong, but reading to teh game as still connected where it was before. Just a guess, though, but it actually is cool... Wear and tear indeed! And your method being so amazingly complicated (that's short of a compliment, I love that splitting SSTO and the absurd fact that it is NOT the main launcher), you were bound to be hit harder by it. Hope you get to the finish line!

Also to the SRB guys and the bright luminary that suggested this is an easy challenge: have you considered that everything outside the 2.5km physics range that is not either landed or in a stable-ish orbit outside the atmosphere gets destroyed by the game as if it had crashed? So yeah, "simple" two-stage designs have to leave their first stage in a sufficiently high suborbital trajectory that they can circularize with the second before the first one hits the atmosphere again to land it. Or, and this is even more difficult, leave the second stage in a sufficiently high suborbital trajectory that the first stage can land before you have to circularize its orbit. Go ahead, try for yourselves, and if you make it work you will be very welcome to post your exploits here. I guarantee you will have a much greater respect to all the people that have finished this challenge regardless of score!

Rune. We are proving the Shuttle lesson, in a way, aren't we?

[Keldaria]

Also to the SRB guys and the bright luminary that suggested this is an easy challenge: have you considered that everything outside the 2.5km physics range that is not either landed or in a stable-ish orbit outside the atmosphere gets destroyed by the game as if it had crashed? So yeah, "simple" two-stage designs have to leave their first stage in a sufficiently high suborbital trajectory that they can circularize with the second before the first one hits the atmosphere again to land it. Or, and this is even more difficult, leave the second stage in a sufficiently high suborbital trajectory that the first stage can land before you have to circularize its orbit. Go ahead, try for yourselves, and if you make it work you will be very welcome to post your exploits here. I guarantee you will have a much greater respect to all the people that have finished this challenge regardless of score!

Rune. We are proving the Shuttle lesson, in a way, aren't we?

Well for the record, no I hadn't considered that since I typically haven't tried to recover stages within that range, and my builds for this challenge so far have only been SSTO so I can't say I really thought about that aspect but none the less point taken and challenge accepted.

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I present to you the 2STO payload lifter, I placed a dummy payload of 3 science labs plus docking ports for a total tonnage of just over 10.5 tons. First stage launches straight up and pushes to about 185k, second stage detaches, does an RCS burn to gain space then a gravity turn burn to reach a stable orbit. I then switched back to the first stage and followed it to landing. Then back at my second stage, I got abit overly critical about the eccentricity of my orbit so I used RCS burns to stablize it at around 175k. Then detached the payload, RCS burned to give me some space to work and set it for landing as well. Now i did use MechJeb for landings, I must admit I'm not really good at the fine adjustments in general and tend to overcorrect. But my piloting skills suck, I don't question that =P.

All in all I wasn't disappointed with the exercise but I still found it a bit easier to achieve this sort of payload delivery than I was having with my original launch vehicle I was tinkering with. It looks like I may have inadvertently created a 2 stage reusable rocket as a result of this experiment, just need to setup a way to refuel and find a better pilot than me to lift off the second stage and carefully reattach it to the first and a crane to reload the payload. I was quite happy with the landing sites of the different stages, I think I'll keep them there.

I might revisit this again someday in the future as I do like the concept of a 2 stage lifter that is fully reusable but I'm happy with this for now. Link below contains the craft file if anyone else is interested in tinkering.

https://www.dropbox.com/s/jv66t66kfdq0a43/2STO.craft

Now I do want to say this, I never intended to say or imply that doing things certain ways were not interesting or not in some way hard. I honestly enjoy seeing everyone's creations and if a 2 stage SRB creation was posted (even one that needed a VAB to recombine & refuel) I would honestly be as interested in seeing how it was accomplished as much as the next creation. My only thought was that the idea of using a VAB to recombine and refuel somehow feels like cheating after all the other entries went to great lengths to not use it. I still respect the attempt, but out of fairness for the other entries I feel those should be kept on a separate leader board or marked on the existing leader board as "VAB used" if their entries are scored.

Also I very much agree, we're learning the lessons of the shuttle with this challenge and that's why I like it =)

Edited April 5, 2014 by Keldaria

[Rakaydos]

I've got a design for a 2STO that can easilly handle a Science Lab, using the Stock Engine Rebalance, stages connected by docking ports for reassembilly, and landing both stages back at the launch site. Reassembilly and attaching the next cargo are what I'm currently hung up on.

[sdj64]

Isn't the hardest part of the 2 stage design getting the second stage back on top of the first stage? (and getting the payload on top of that)

You could make a two stage rocket craft with two side boosters that are attached to the core via docking ports. That way the side boosters and the core could both land upright on legs, and a rover with a docking port at the right height could dock them back together without needing to raise or lower anything. You would still need some way of getting the payload on top though.

[Rakaydos]

Isn't the hardest part of the 2 stage design getting the second stage back on top of the first stage? (and getting the payload on top of that)

You could make a two stage rocket craft with two side boosters that are attached to the core via docking ports. That way the side boosters and the core could both land upright on legs, and a rover with a docking port at the right height could dock them back together without needing to raise or lower anything. You would still need some way of getting the payload on top though.

The problem is landing *both* boosters. Perhaps if you could RCS the boosters together and land them as one unit?

My current approach is to have the upper stage having a surface TWR of <1 including payload. This lets it circularize with plenty of time to get back to the booster, and lets it skycrane a payload. Unfortunately, I've been having probems getting a Sr docking port to dock under kerbin gravity

Edited April 6, 2014 by Rakaydos

[Keldaria]

Isn't the hardest part of the 2 stage design getting the second stage back on top of the first stage? (and getting the payload on top of that)

Yes, Re-docking the second stage is a problem, I was able to do it on mine but it took me few tries and a good portion of fuel each try, even after getting my second stage on top of the first (which it helped that my first stage was fairly wide and flat) it took a few times jumping up and down on the docking port for it to truly take. At any rate I couldn't imagine having to do that process multiple times after each orbit... I'm thinking I might adjust the second stage to fit under my first (I know, Ironic isn't it?) and have it clamp in like my other proof of concept. Let the first stage take me into space without any gravity turn, then release and back away my second stage with RCS and then proceed like normal. The under mounting of smaller stages and payload makes it easier in my opinion to connect outside of the VAB, even if your still using a docking port to connect, it should be easier to rover under a rocket and boost straight up to connect than to try and land on or build a crane to service the exact height. Of course that relies on me being able to design a primary stage that is wide enough to slip smaller stages/payload between the 4 "Legs" and/or design a rover that can fit between them as well to move it into position...

You could make a two stage rocket craft with two side boosters that are attached to the core via docking ports. That way the side boosters and the core could both land upright on legs, and a rover with a docking port at the right height could dock them back together without needing to raise or lower anything. You would still need some way of getting the payload on top though.

The problem is landing *both* boosters. Perhaps if you could RCS the boosters together and land them as one unit?

My current approach is to have the upper stage having a surface TWR of <1 including payload. This lets it circularize with plenty of time to get back to the booster, and lets it skycrane a payload. Unfortunately, I've been having probems getting a Sr docking port to dock under kerbin gravity

When I was first putting together my original 2STO design, I had intended to use an under mounted mainsail engine for second stage which meant I would have had to use side mounted tanks in a similar fashion to the boosters that you mention, but I quickly revised that plan when I couldn't think of an intelligent way to make all the tanks disconnect and remain 1 piece. I hadn't thought about having the boosters recombine themselves after being decoupled, I'd love to see somebody put that in action, I would try myself but I'm not good enough with RCS docking to dock before I hit the atmosphere again (I'm one of those people that does his docking at 0.1m/s)..

At any rate, I might have to tinker with my design some more tomorrow if I can find the time. I really want to see if combining my 2 designs would work as intended or not.

[gchristopher]

Well, at least I have more fun failures to share!

The RCS tug ("Alaskan Mosquito Mark I") was just a little bit too large to dock the cupolas in position, so I sent a little scaffold up with the second cupola delivery flight. Kinda an extension that was intended to hold the cupola at arm's length and a more convenient orientation. I'll have plenty to say about why I hate cupolas when this is over.

Buuuut, the scaffold docking port joints are way, way too floppy for reasonable RCS operation. SAS is out of the question, because it just oscillates wildly if you turn it on.

So, I downloaded the MechJeb source code and made a few changes to address the backing up bug and see if I could reduce the wobble.

Maybe it's time to send up "Alaskan Mosquito Mark II, the Claw Edition!" I wonder if grabbing stuff with the claw would be a better option if some idiot decided to send a space station up in 20 different pieces and put it all together in orbit. Sending up the KerblArm (Mark III) isn't an option until Infernal Robotics recovers from the 23.5 update.

(Edit: well, that took 10 minutes to investigate. Claws are way, WAY better. Guess I'd better get around to deorbiting and sending up another mission.)

Edited April 6, 2014 by gchristopher

[Mecha Pants]

I've given up on my previous attempt with claws, and I've run into another snag with my smaller, lighter SSTO spaceplane.

If I have one station module that is significantly larger than my SSTO's payload space, is it acceptable for me to attach it to the top of my first lift with a decoupler, provided all further modules use the docking port in the cargo bay?

For demonstration:

The actual cargo bay is between the engine intake nacelles and is about as big as a mk2 fuselage section. I can fit single kerbal pods and small sub-assemblies, but not the lab or habitat units needed for an entry. so I decided to try and lift it this way.

For the record, I'm surprised it even flies with that thing stuck on top.