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[REUSEABLE ROCKET] 1 Rocket 1 Station


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I thought Pine's entry was good, so I took some inspiration. Is that all right? And the tug module now is the third module of the station. I'll just pass it off as a "fuel module"

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1 hour ago, Bev7787 said:

Complete with orbital tug payload. Why it has to flip upside down before burning? Needless complexity, that's why!

Awesome!

 

Okay, I've finished a trial run of a candidate reusable rocket for this challenge ruleset, "Fjorklifte". It's Y-shaped and designed to accept an underslung cargo of around 20 tons. It's all stock parts. Here's a picture of it on the launch pad with a potential Mun station core module. 

trial_launchpad.jpg

I have a question about the refueling process under the rules. Right now there's no stock way to refurbish heat shields, and the part options for reentry are pretty limited. This design uses four expandable heat shields, which keep it alive and more importantly, make its flight characteristics in reentry very predictable. I think repeated landings close to KSC are doable. Here's a picture about 1.5km out, landed on a trial run with Valentina piloting:

trial_landed.jpg

There's no stock way to refurbish any of the heat shielding parts. :( All four heat shields are attached by docking ports so they can be jettisoned and new ones attached. TheKSPDesigner, would it be acceptable under your rules if I built a rover to bring over and attach new heat shields as part of the refueling process?

 

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20 tons!?

My conpleted station is about 13 tons! Jeez mate! :D    

I'm almost done with my entry video, and really excited to show you all my entry (which now is not the biggest thanks to you guys).

@gchristopher, maybe if you don't recover the heat shields it might be acceptable, since the rule just says no recovery of launcher. But we need @TheKSPDesigner's official answer. 

To the OP, is it alright to after sending an entry, making another one, if just to do the hard mode?

Edited by Pine
Mobile editor sent this before I was done writing. :p
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5 hours ago, Pine said:

20 tons!?

Ummm, actually, I kinda haven't built anything in KSP in a long time, so I really had no idea what the payload capacity is. It can actually lift quite a bit more. The lifter has an unladen takeoff mass of 1327.155 tons.

I did some trial launches with higher payload weights, delivering to an 85x85 orbit and returning to KSC

Trial 1 was with an 81.4 ton payload:
Launch mass was 1408.555t, for a 7.8% payload fraction.
Landing was 300m from launchpad! Mass at landing was 272.089t, with 653 atmospheric dV remaining.

Trial 2 was with an 121.9 ton payload:
Launch mass was 1449.055t, for an 8.4% payload fraction.
The landing was  a bit short, 3km-ish from the pad. Mass at landing was 267.651t , with 605 atmo dV remaining.

So, at least for a low-drag, streamlined payload, 120 tons is within a safe margin of error. It's not going to win any awards for efficiency, though!

Liftoff TWR (reported by MechJeb as SLT?) is down to 1.06. (It says TWR is 1.13) That's low enough to be a concern for adding any more mass, plus I don't plan on needing a 300 ton space station, so this lifter is certainly powerful enough for any plans, assuming it can be reloaded and @TheKSPDesigner is okay with letting a service vehicle replace the heat shields after landing. That seems to be in the spirit of the challenge, because all refurbishing happens outside the VAB.

If heat shields are off the table, max payload will be reduced quite a bit to save dV for reducing speed during the critical heating section of reentry required for a vehicle this large. I really want to avoid a mid-atmosphere burn because it makes predicting the landing location really annoying, and spaceplanes aren't permitted under the challenge rules. 
 

Edited by gchristopher
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Finally uploaded the video to youtube, so here's my entry:

 

I'm tired, so the score is at the very end of the video. Tomorrow I'll write it down, I need to sleep now.

 

EDIT:

My score is 12,393 points!

 

Edited by Pine
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On 7/3/2016 at 5:49 AM, gchristopher said:

Awesome!

 

Okay, I've finished a trial run of a candidate reusable rocket for this challenge ruleset, "Fjorklifte". It's Y-shaped and designed to accept an underslung cargo of around 20 tons. It's all stock parts. Here's a picture of it on the launch pad with a potential Mun station core module. 

trial_launchpad.jpg

I have a question about the refueling process under the rules. Right now there's no stock way to refurbish heat shields, and the part options for reentry are pretty limited. This design uses four expandable heat shields, which keep it alive and more importantly, make its flight characteristics in reentry very predictable. I think repeated landings close to KSC are doable. Here's a picture about 1.5km out, landed on a trial run with Valentina piloting:

trial_landed.jpg

There's no stock way to refurbish any of the heat shielding parts. :( All four heat shields are attached by docking ports so they can be jettisoned and new ones attached. TheKSPDesigner, would it be acceptable under your rules if I built a rover to bring over and attach new heat shields as part of the refueling process?

 

Absolutely! As long as the actual booster doesn't go back into the VAB/SPH :wink: By the way, very impressive! :D

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On 7/3/2016 at 8:19 PM, Pine said:

Finally uploaded the video to youtube, so here's my entry:

 

I'm tired, so the score is at the very end of the video. Tomorrow I'll write it down, I need to sleep now.

 

EDIT:

My score is 12,393 points!

 

That's awesome, Pine! Way to go!!

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I use a pair of aircraft landing gear to push the whole thing up just a bit so that it connects, but it's a pretty finicky thing to do. Unless is fits by just a hair, it won't work. Or you could use bigger landing gear to lift you higher.

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For reloading, since I went with the (easiest) option of having an underslung payload, I used a carrying gantry that held the payload docking port juuust lower than it would need to be to dock to the rocket. I used Docking Port Alignment indicator to drive it directly underneath the docking port on the rocket. Then I set the brakes on the rover/gantry and fired up six radial Thud engines to slam it up into gently raise the payload the payload the final 0.4 meters to dock.

reloading.jpg

BTW, if you're ever going to try the Kerbal Attachment System or Infernal Robotics mods, this challenge is a fantastic time to do so and I highly recommend it. All those options for winches, Kerbal-movable fuel lines, and moving parts create so many fun possibilities that you simple can't do with the stock game. 

Edited by gchristopher
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Okay! Since the post 1.0 changes, the most significant new parts of the game are the new aerodynamics, and reentry heat. Launch is pretty easy to solve, just streamline your vehicle, keep your AoA low, and find a new ascent profile. 

Reentry heat has been a lot more challenging, and I wanted to explore options for coming back in. There's lots of good advice on the forums about finding the right reentry profile, but I was hoping to demystify the process a bit. 

Through testing, I think I have, and I'm pretty disappointed with my preliminary observation. It turns out: ALL YOU NEED IS DRAG. That's right, part selection, heat shields, well-timed retro rocket burns, careful angle-of-attack flying etc, etc, really pale in effectiveness to just finding a way to increase your drag. This is what keeping your nose up in a spaceplane reentry accomplishes, and rockets really have few options to do. 

Here's a quick walkthrough of variations of reentry options I tried. For all, I was returning from 85x85 LKO using a 30 km periapsis for the reentry profile, a pretty standard conservative reentry.

I started with an attempt to have heat shields protect most of the rocket, which meant they were clipped through the engines a bit. This design reentered and landed great, but is cheesy because of the clipping, and also the heat shields tended to explode when jettisoned. Amusing, but bad for the reusability of the rocket.

reentry1.jpg

Then I wondered: what if the extra drag from the heat shields is enough to reenter safely, even if the heat shields don't actually protect the rocket at all? Turns out that yes, just having some big draggy deployed heat shields NEXT to your rocket is just as effective for a safe reentry as if the heat shields were actually shielding the parts. 

reentry2.jpg

That was a disappointing discovery, because the KSP part catalog is virtually empty of parts that serve the now-vital purpose of increasing drag for rocket reentry. The AIRBRAKES are small, wimpy and have very low heat tolerance, so they're not useful for reentry at all. 

But Infernal Robotics provides some quite strong hinges, so let's try making some gigantic Airbrakes using wing parts that can serve as rocket fins for ascent, then flare out on reentry.

That worked embarrassingly well, even better than the heat shields. None of the rocket parts heated up enough to have a heat bar from the reentry. It also looked awesome. Stock KSP really needs to provide some parts like that, or some other way to improve reentry options!

reentry3a.jpg

reentry3b.jpg

But since this challenge is intended to be a mostly stock affair, I kept looking at options for reentry that didn't rely on any part mods. My first try with the inflatable heat shield used 4, which are work to replace, so I tried again with 2. This time there was some heating on reentry, but nothing got to scary or dangerous levels. 

reentry4.jpg

Lastly, I wanted to explore options to increase drag that didn't rely on the inflatable heat shield, because it's annoying to have such a critical capability hinge entirely on a single part in the KSP catalog. 

What if you put some giant fins (delta wings) on docking ports, so you could bring up a little RCS tug and have it move them to a 90 degree angle in orbit, so they'd add lots of nice drag on reentry? That worked fine for ascent!

reentry5a.jpg

I put the little RCS tug back in its hangar bay and tried a reentry, using the same profile as the others. 

reentry5b.jpg

Docking ports are comically too weak for this application. They quickly flexed flat against the rocket, before flopping uselessly (but amusingly) around, before the entire rocket exploded from the heat. 

reentry5c.jpg

The version with just two inflatable heat shields has done two launch/deploy payload/reenter/land cycles, so that's the one I'll be using for the challenge, even though the Infernal Robotics Mega Airbrake one is by far the coolest and my favorite. 

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  • 2 weeks later...

This thread got quiet! Well, here's a complete attempt, with three launches. The reusable rocket was named the "Fjorklifte." The crawlers were iterations on the "Fuellio" refueling system. The orbital tug was put up to the internet to vote on a name, and a write-in, "Spacey McSpaceFace" won by a large margin. 

It inadvertently accomplishes both the regular mode and hard mode versions of this challenge, because each launch had 2 payload sections, one of which went toward an orbital station in 125x125 LKO, and the other of which went toward a Mun base that travelled to the Mun and landed under its own power. 

Here's the picture album!

Including the cost of replacing the heat shield module, the launch costs came out to about 1200 funds/ton. That's probably much better than a non-reusable system, but I don't have current numbers for 1.1.3 to compare against.

Scoring:

The Orbital Station is a docking and utility station consisting of a Research Lab, a variety of fuel containers, "Spacy McSpaceFace" orbital tug, a smaller RCS tug, and six Y.I.K.E.S. pods, each capable of returning one Kerbal safely to the surface. (That stands for YIKES Individual Kerbal Escape System.)

Mass: 119,065 kg
Cost: 213,072 funds
Score: -94,007 !

Woohoo! Despite a score well into the negative numbers, that puts this entry into second place, as of this writing, behind the other finisher, Pine. 

 

The Mun Base has both solar and RTG power, a full complement of all science equipment, two drills, and one ISRU. Carefully managed, it can achieve over 7,000 dv, and refuel at its destination. 

Mass: 129,945 kg
Cost: 437,924 funds
Score: -307,979 !

Despite the huge negative score, I think that puts it in first place, since no one else has done that part of the challenge!

 

Hopefully @TheKSPDesigner returns to update the OP with the entries so far. Thanks for the fun challenge!

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