🚀 The Kerbal Thread - Share Your Kerbal Creations



  • @FrostCat said:

    Since I don't play KSP, I don't know this: why do so many designs put the thrusters at the top, like in @blakeyrat's latest set of pics?

    The VAB (vehicle assembly building) has a height limit, and that rocket I built to deliver fuel was right at the limit. There's no way to stack 4 Kerbodyne tanks, plus the height of an atomic motor, plus room for 2 more stages to get the thing into orbit.

    The other ship in the first post here with engines in front was used for towing asteroids. The motors were in front because if you block an engine's exhaust, you also block its thrust-- putting the motors in back wouldn't have moved the asteroid, they would have just pushed on the asteroid and yanked on the grabber arm until it tore off.

    Also, all of Goddard's first liquid-fueled rocket designs had the motor up front.

    @FrostCat said:

    Obviously in the real world that would tear itself to shreds;

    That's not at all obvious. All the "pulling" vehicles you've seen in this thread don't start pulling until they're in a vacuum, where the stress is much less of an issue.


  • Discourse touched me in a no-no place

    @accalia said:

    Pendulum fallacy.

    While that was interesting, I'm not sure it actually answered my question. Blakey said his rockets do that for a specific reason, which is fine, but real rockets still put their engines at the bottom.


  • Discourse touched me in a no-no place

    @blakeyrat said:

    FrostCat:
    Obviously in the real world that would tear itself to shreds;

    That's not at all obvious.

    Well, I guess it depends on how tough your struts are. From the pictures they seemed kinda wimpy. Maybe they're more sturdy than they look.



  • @FrostCat said:

    Well, I guess it depends on how tough your struts are.

    Fair enough. Given that each atomic motor weighs 2.5 tons, and I had two per strut, it's unlikely that arrangement would work in real life.



  • My first lunar science satellite sitting on the platform, awaiting blastoff. It's ugly but ought to get me easy points every time one of those "Transmit Science Data From The Mun" contracts shows up.



  • Epic fail. Ran out of fuel halfway through the burn that was supposed to take me to the Mun.


  • FoxDev

    i run by a rule. work out my deltaV budget for the trip. then multiply by 2 and build that rocket.

    usually just barely make it where i wanted to go, but i do get there.



  • I don't know the maths yet, it's mostly trial-and-error for me. I threw on an extra liquid fuel tank, 8 small SRB's, and giving it another go. I was actually pretty close last time as far as delta-v.



  • I think I made it this time. I'm on course and have half a tiny fuel tank left which ought to be just enough to slow down and get captured by the Mun.

    Not much left of the ship once I drop off everything I needed just to get it this far!


  • FoxDev

    FYI, if you install remotetech those antennas you have installed there are not going to reach Kerbin. You'll have to send up a relay to get the data home.

    on the other hand the relay should be much lighter! :-D


  • Discourse touched me in a no-no place

    @blakeyrat said:

    Given that each atomic motor weighs 2.5 tons, and I had two per strut, it's unlikely that arrangement would work in real life.

    That's all I meant. I get, from the video, that putting the engines on top has a magic effect of apparently obviating the need for stabilizers or whatever, it just still seems weird. For a regular rocket, not the special purpose pullers you picture above, putting them on top must give enough of some kind of benefit to make it worth doing.


  • FoxDev

    well not really. making huge rockets in the VAB is hard because there's a height cap. there are ways around that to a limited degree, but only so much.

    so building out is required at some point.

    and in a puller rig you want to do that so you cold your docking points under tension rather than compression.

    but for a single, solid rocket you get no benefit (other than perhaps making it fit in the VAB)


  • Discourse touched me in a no-no place

    @accalia said:

    [height cap] so building out is required at some point.

    There ya go, that's probably what I was looking for. I will acknowledge Blakeyrat said it first but it didn't click that was the answer.

    @accalia said:

    and in a puller rig you want to do that so you cold your docking points under tension rather than compression.

    Does too much at the bottom cause the bottom to go through the top, like the punchline to the joke "what's the last thing that goes through a mosquito's mind when it hits your windshield at 80mph?"


  • FoxDev

    well it's pretty much like that.

    if you have a stick, a solid piece of wood it doesn't really matter where you push it so you might as well stick the rockets at the back of it where it's easier to plumb.

    but when you have multiple modules docked together you end up with something much more like a chain, you can push it from the back, sure but that way is really hard to keep the chain straight and untangled. for that style of rocket it's easier to pull.



  • Thinking about a new Laythe concept.

    The idea here is to use my wings and jet engine to slow and find a nice landing spot, then use the VTOL to land softly, then there's a complete return capsule built-in to get back into orbit. My pilot transfers to it, and bam.



  • Looks fairly balanced - I like the twin 800 tanks on each side. Why not ram intakes or shock cone intakes, though?



  • Because I have no fucking clue what I'm doing when it comes to airplanes? It turns out that as soon as I turn off the VTOL engines (with a forward speed of about 90 m/s) the thing falls like a stone.

    The balance for VTOL is fine, but the instant I turn the VTOL off, it's crashmode. Oh well.

    Maybe I'll work on my Jool station, I have all the parts I need now.



  • My guess would be that you need more wing - those tanks get heavy quickly and it looks like you've got about 30+ tons of them when full. You could also swap them for the Mk2 fuselages as those tanks add lift as well.

    Ram air intakes and shock cone intakes are the best if you're trying to maximize intake air at high altitudes (for an SSTO) as they have the best intake area. Circular intakes aren't much worse, though, and if this is mainly going to be doing low-altitude cruising, it probably doesn't matter, since you've got the return capsule for ascent.



  • Hey lookie, I built a plane that can actually fly, and is reasonably controllable too. Wooo.



  • Holy crap, flame-outs are disastrous. Still, single stage to 24950m on my very first flyable airplane ever. Woo.

    EDIT: I got down to 13,000 and it's flyable again, let's try landing!!!



  • @blakeyrat said:

    EDIT: I got down to 13,000 and it's flyable again, let's try landing!!!

    I predict explosions.



  • Me too. Kerbal is pretty shitty as a flight sim. To be fair, that's not what it was designed for. But still.

    Also I think I f-ed up my navigation and missed the space center by miles, hahaha. I got plenty of fuel, but getting bored of just flying... I'll land on the first thing I see that looks flat.



  • Approaching my "perfect" landing area in the foothills.

    At this point I actually had to pump fuel forward to keep my plane controllable... once the forward-most tank was full I could actually steer it again, haha.

    And...

    Touchdown!

    Any landing you can walk away from!


  • Discourse touched me in a no-no place

    @blakeyrat said:

    At this point I actually had to pump fuel forward to keep my plane controllable... once the forward-most tank was full I could actually steer it again, haha.

    That can actually happen with real planes, especially small ones.



  • @FrostCat said:

    That can actually happen with real planes, especially small ones.

    Oh I know. Big planes do it too. 747s pump fuel all over the damned place to keep trim during flight.

    How do you control which engine flames-out first? You can't pipe air right?



  • My next attempt at SSTO, pictured here in the VAB before I even try it once. So it's sure to fail.



  • @blakeyrat said:

    How do you control which engine flames-out first? You can't pipe air right?

    You don't.

    The trick is to keep an eye on the inlet air gauge, once it starts getting low, shutdown the air-breathers and switch to rockets. I want to say you'll get flame-outs on one engine when your around 0.05 air. I don't know if you have to take into account the number of engines. More intakes means more air at higher altitudes!

    I usually bind an action key to do that. 1 turns on the jets and turns off the rockets, 2 turns on the rockets and off the jets.

    Also, I am so glad they integrated Space Planes+ into stock. The new parts look awesome.


  • Garbage Person

    @blakeyrat said:

    How do you control which engine flames-out first? You can't pipe air right?
    Placement order. Two engines placed simultaneously don't flame out symmetrically, though.

    So put your first jet engine on the centerline. When it dies, rockets on, kill all the other jets, and switch the centerline jet back on until it flames out one final time (it might not be much, but it's basically free thrust compared to rocket fuel consumption)



  • Ok, after a bunch of revisions, here's a version of that jet that can actually fly. Whee.

    @nullptr said:

    The new parts look awesome.

    The QA on them is pretty lousy. The Mk2 Clamp-O-Tron has "toggle" (lowercase) as a right-click action. What does toggle mean? "Open Shield" it seems.

    Also there's no nice way to "round-off" a Mk2 rear end, you can see in the screenshot I just left mine bare.



  • Yet more revisions, this is probably the most stable aircraft I've built so far, and it has everything it needs to be in orbit (solar cells, batteries, SAS, RCS, docking connector, etc.)

    I'm sure it'll go into a unrecoverable stall any moment now, but hey.



  • Having an odd number of jet engines makes the flameout problem much easier to manage, since you can shut off each outer pair of engines as you run out of air. If you can make your craft light enough that it flies with a single jet engine, even better.

    R.A.P.I.E.R. engines make designs simpler and keep engine mass down (since they double as rocket engines and weigh as much as a turbojet), but I've found that I can get much better results with turbojet + LV-N designs.

    @nullptr said:

    I usually bind an action key to do that. 1 turns on the jets and turns off the rockets, 2 turns on the rockets and off the jets.

    I typically set 1 = toggle jets, 2 = toggle rockets because I often run them simultaneously once at altitude.



  • It flames-out at 900 m/s at a bit over 24,000 m.

    There's enough fuel that the atomic engine should have no problem from there, the challenge is it's a heavy ship and only a single engine.

    But really the important thing is: it LOOKS cool.


  • Garbage Person

    You know, nuclear engines in the atmosphere of a habitable world just amuses me for some reason.

    Kerbals are really just the well resourced version of the Russian space program: Halfass, but HARDCORE.



  • Oop, it's looking like one atomic is insufficient for this plane, I thought i tmight be. Putting another one on is going ot mean another huge round of rebalancing hmm.


  • Garbage Person

    In other news, Satcom-3 is on its way to join the constellation. Took me forever to get #2 positioned just right.

    (Why does it seem that like 80% of my launches are at night?)


  • The old rule of thumb for SSTOs was about 3-4 ram intakes per engine if you can fit them. That should keep you going at 30km and above. Shock cones are more effective, but I don't know by how much.

    I consider radial intakes and engine nacelles/radial engine bodies to be roughly 1/2 of a ram intake.



  • Yeah. This shot was taken basically at the absolute ceiling. I added some radial intakes to balance the second atomic motor, but as you said they don't add much.

    The atomics are way too wimpy, ironically because there's still too much fuel in the tanks by the time they fire. I gotta do some major revisions here.

    @Groaner said:

    The old rule of thumb for SSTOs was about 3-4 ram intakes per engine if you can fit them.

    How are you supposed to do that without the rocket looking like ass? Haha.



  • @blakeyrat said:

    How are you supposed to do that without the rocket looking like ass? Haha.

    There we go, more intakes via. cheating (overlapping parts).


  • Garbage Person

    Need to shift my satcom constellation up. 1000KM is too low for reliable contact (thanks, planet!)

    Fortunately these things have shedloads of fuel.



  • Ok well time to make dinner. Not an altogether successful ship, but more successful than I expected. And I learned a lot for next time.

    Also if the wings and engines break off it doubles as a yacht. (I love how presumably steel or titanium I-beams in Kerbal float.)


  • Discourse touched me in a no-no place

    @blakeyrat said:

    Also if the wings and engines break off it doubles as a yacht.

    That was actually a plot point in Condorman.


  • Garbage Person

    @blakeyrat said:

    Also if the wings and engines break off it doubles as a yacht
    .... Can you build a yacht in KSP? A JET YACHT!

    TO THE SPACEPLANE HANGER!



  • Yeah I've build boats before. They're actually quite a bit easier than things that fly.

    Use those light medium drum connectors as floats.



  • My momma always told me to aerobrake in Jool's atmosphere around 120km. This time, I aimed for 115.

    And it was a bit too steep this time, but it's not too much of a transfer to our destination...

    Orbital capture was a pain (since that high apoapsis required a lot of slowing down), but this happened anyhow.

    Let's go do the Bop.

    Vall is our final landing destination for this craft before Kerbin, since it can't land on Tylo or Laythe. I was quite happy with this series of maneuvers...

    Then, all of a sudden, Tylo comes along to ruin the day.

    Now that the trajectory has been corrected, let's land on the side of Vall facing Jool, which also happens to be dark right now.

    Laythe and Tylo are forthcoming, but Mission Control wants me to explore some boring rocks called Dres and Moho first.



  • Dres is only tough because there's no aerobrake. Moho is more of a bitch, still no aerobrake and a lot more delta-v needed to get there.



  • Applying what I've learned.

    EDIT: I ain't learned shit.


  • Discourse touched me in a no-no place

    @blakeyrat said:

    EDIT: I ain't learned shit.

    PICS! Unless the crash was meh.



  • Oh it just ran off the end of the runway with no lift, and hit the water at 110m/s. That Skipper provides tons of thrust, but no way it's light enough to be "plane-able".

    Here's a revised design which is plane-able, but I know the rockets are too wimpy on it:

    It's a single LV-T30. But at least ti can feed fuel longer than 45 seconds, unlike the Skipper. EDIT: BTW there's a underslung central engine not visible in that screenshot.

    Is there a way to firm-up the wings so they aren't so flappy? Also fuel lines are so ugly, but I don't see how to build designs to prevent needing them.



  • Getting closer to flame-out, but it's still doing ok.


  • Discourse touched me in a no-no place

    @blakeyrat said:

    no way it's light enough to be "plane-able".

    Just how big can you make the wings? If you expand them to the VAB limit, what happens?


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