ComradeGoat

With air breathers, you get the efficiency in the flatter ascent profile from not having to carry oxidiser. Given that your plane is rocket-powered, I'm thinking doing an aerodynamic flight ascent rather than a ballistic ascent is just going to waste fuel fighting gravity. I guess wings on a rocket are useful in the event it doesn't have enough thrust in the lower atmosphere to climb, and so needs the wings, but otherwise it would seem more sensible to just go straight up if you are carrying your own oxidiser.

Interesting approach - a non air-breathing SSTO! I guess the question is, does this work just as well without the wings, as it seems to go pretty much straight into a vertical climb and use a rocket ascent profile, rather than a plane ascent profile?

I started by building SSTO VTO craft in the VAB. Taught me a lot without throwing the whole "and now you're building planes" thing at me too. Probably a shallower learning curve.

That's incredibly impressive! I hope we get stock hinges.

There seems to be quite a trick to designing one which will handle nicely at low altitude and hypersonic flight. Part of the fun I'm having is working out why stuff that works when I do it intuitively works in theory, so I can improve the next design. The poster who said this is *hard* is right. It seems to be far harder than anything else in the game; it's almost a full game in its own right, but I am having *so* much fun!

I accidentally a Swiss Army plane! Better than my previous attempt, it'll do full throttle at 30K without the strut intake mounting trick and doesn't need a "kick" from fuel thirsty high thrust rockets to get into orbit: it'll do it on a Nerva and the 2 jets only. Enough Delta V to reach Duna and beyond, can land on the Mün and return, and unlike my previous attempt, isn't an utter dog to try and get off the runway (previously had to put the wheels further back than I'd have liked to avoid smacking the NERVA into the ground on rotation. Have solved by pulling the NERVA forward into a central cavity I left for it).

Part of my learning curve has been to discover that the drag matters, a *lot*. If you have more drag on the bottom or the top, it will pitch uncontrolably in hypersonic flight. Similarly, if your centre of thrust is too far behind the centre of mass, the plane will try to pitch forward under power, and it will do it more the faster you get.

Aerospikes (I note plural) have considerably more thrust than a single NERVA, which is rather gutless.

Thanks. I'll look into the Lazor mod. This does seem to be a bit of a showstopper for using the inline docking port!

Ah, replies to this remind me of that old joke: "Doctor! Doctor! It hurts when I do this." "Well don't do that, then."

With my recent foray into space planes, I find myself using a component I haven't used before: the inline docking port. So there I am with my spaceplane a few dozen metres from my fuelling depot in LKO, and I am ready to dock to transfer fuel. Open the port, select "control from here", watch the navball jump by the expected 90°, and bring it in on translational RCS. Got a beautiful approach lined up, closing speed 0.2m/s, flying with the yellow circle perfectly centred on the purple circle, and boing! It bounced off. "That's odd", I think, so I try it again, with the same result. The next time, I turn the camera to see the two ports approaching and see the problem. Despite having control from the docking port, the navball is apparently lining up my cockpit with the station's docking port, leaving the plane's docking port a few metres away, bouncing off the side of the space station. Is this a well known bug that I've only just encountered? The navball switches its horizon to where I would expect it to be, but not its point of view, as it were. This does make using the inline docking port rather more of a challenge than it would otherwise be!

I'm using both of those. Also, Haystack (never again end up screaming, "BUT I'M CLICKING ON THE SPACE STATION, NOT THE DEBRIS! STUPID COMPUTER!" and Subassembly Loader (which would be much more useful if it didn't mess up fuel lines and struts);

Ah! Cunning. Thank you. Best I have so far is 6:1 (the one pictured above), which gets me to 28K. Not *quite* enough to get to orbit on just a NERVA afterwards

Wow! How are you mounting all those intakes on the leading edge? I seem to have to stick them on fuel tanks.

OK, really getting the hang of this now. Just finished the final tweaks for this, the Minerva-DSV (Deep Space Vehicle) SSTO. Takes off from a runway, operates to 28,000m on jets alone under full thrust, enough delta-V to go from the runway at the KSP to Duna orbit without refuelling. Bit of a princess below 8,000 metres, but handles beautifully in hypersonic flight and has pretty decently balanced RCS for something that's such an awkward shape. Very pleased with this:

I posted a pic of the prototype. Here's my practical spaceplane, in orbit round the Mün, after refuelling:

As someone said above, a lot of getting it to work is about how you fly them. If I explain my ascent profile, the ram intakes may become clear: Take off from runway with just the ram intakes open (scoops closed due to drag), climb at 45° and terminal velocity (ish) to around 14,000. Reduce angle of attack to 30°. Climb to around 20,000. Level off. Accelerate hard up to about 1,000 m/s in straight and level flight. Open air scoops, start to climb at 50-100 m/s rate of climb. At around 25,000 metres and something like 1,200 m/s, the air starts to give up (people better at this than me can get this higher). Throttle back to about 50%. It's usually about now that I kick in the aerospike. The plane is still climbing, but under reduced power and the acceleration has slowed. The aerospike, together with the jets at lower power, keeps the acceleration and ascent going. Keep reducing power to prevent flameout Somewhere around 30,000 metres, it starts to get tricky. There is almost no air left. The jets are sipping fuel, as is the aerospike. Using them much more risks a flameout. At this point the plane is traveling at about 1,500 m/s. if we wait any longer then we will catch up to the apoapsis and start to descend. This is bad. Kill the jets, close all air intakes. Full throttle immediately. The aerospike roars to life. Check map view. The apoapsis should be in front of you and running away. If it looks like you're going to catch it up, increase your angle of attack. BE CAREFUL. If your plane isn't well balanced, changing the angle of attack here could cause it to spin out of control. My earlier attempts were prone to this and needed RCS assistance at this stage. Now I'm building them somewhat better! Watch the navball change from "Surface" to "Orbit". With the plane still below 40,000 metres, the apoapsis will shoot away and a periapsis will appear. Let the apoapsis climb to around 100,000 metres and cut the power. Atmospheric friction will now start to bring the apoapsis back down, but we have built up enough speed and have enough vertical momentum to carry us clear of the atmosphere before it drops below 70k. Glide to orbit, circularise, feel smug. That's why you need the air intakes. The jets formidable ISP and power means they can push the plane through the atmosphere and attain speeds that would require very heavy rockets to match. If you have to switch to rockets at altitudes where the air is still producing a lot of drag, you will burn all your fuel trying to keep the apoapsis in front of you, and the fall back to Kerbin. It's all about going as high as possible and as fast as possible on jets alone, so that the fuel-thirsty rocket has to do as little work as possible.

Gladly! This is the first one I few to orbit. It's a prototype and doesn't have the docking capability, or much of anything. It's now evolving into a practical design with a more fuel-efficient ascent (intake air, intake air and MOAR intake air!) and all the comforts of home, like properly balanced RCS, a docking port, lights, etc.

ASAS will prevent you from turning. It tries to hold your heading. You need to turn it off to turn! All command modules have reaction wheels to turn, but the small ones don't have much turning force. If you have a small command module and a great big heavy ship, the control wheels aren't going to do much, and as others have said you will want to augment with strategically placed RCS thrusters.

Every so often, while exploring the solar system, I would notice the funny little building with its funny little runway, and decide to have a play. This would invariably result in something that accelerated along the runway like a demented thing, didn't actually take off, and careered into the sea as it turned into a fireball. "Spaceplanes will never work for me", I thought, and returned to rockets, impressed by all those people with their amazing SSTO designs. Then I stranded a couple of Kerbals on Laythe after botching my insertion, and feeling the need to go and rescue them, started to try and build an air breathing lander to descend to Laythe's surface and return to space, all in one stage. But how to test such a thing? The only realistic way was to develop it on Kerbin, which has a larger gravity well. If it works there, it will work on Laythe. My initial design just about worked, but my ascent profile was awful. I switched off the jets at a mere 600 m/s and clawed my way to orbit on a pair of aerospikes, arriving there with almost no fuel left, with most attempts not even doing that and falling back to Kerbin. I got a few tips here, and my final design is something I'm actually rather proud of. It takes off vertically, gets to around 1,200 m/s before firing up the rockets, and arrives in orbit with plenty of fuel to rendezvous and dock. During development of this though, I learned a lot abut how to get an SST vehicle into orbit, and slowly figured out the variables I had to balance to get the thing to behave through hypersonic flight into the high atmosphere, and then transition to the orbital insertion rocket burn. I played around with one or two vertical take off SSTO designs, managing one that was able to get out beyond Dres' orbit without refuelling, all in the VAB. And then it occurred to me that I'd probably climbed most of the learning curve I needed to climb to build an actual spaceplane. So I'm pleased to report that, after returning to the SPH, I have now built, from scratch (not modifying a stock design), an SSTO, piloted spaceplane that can ascend to orbit, dock, reenter and land. My first practical design is nicely balanced and behaves beautifully in hypersonic flight, unlike my first attempts where touching the controls between 18,000 and 35,000m would typically be followed almost immediately by an abort to surface, if the vehicle actually stayed together! No-longer am I terrified of the dark arts practiced in the SPH; things seem to have "clicked", and I have a feeling that my standard way to get kerbals into space will now involve taking off from a runway. It feels like a whole new area of the game has opened up! Is it just me though, or is building a working SSTO spaceplane just about the hardest learning curve in the game? Docking was a piece of cake compared to this.

My interplanetary workhorse vehicle, which is powered by 2 NERVAs and a 12 (count 'em) mainsail powered heavy lifter is balanced so that you can more or less sit it on the pad, select 100% throttle, and do a near fuel-optimal ascent without shifting it from there right the way to the end of the ascent. Careful tweaking of the weight, asparagus staging, and the TWR or each stage ensures that it stays close to terminal velocity all the way up to 10K. Ultimately, where you set the throttle to get a fuel optimal ascent will depend on how you've designed your ship, and the granularity of the staging (large stages produce much more thrust when they're nearly burned out because they're a lot lighter).

SSTO using what appears to be a chemical rocket from Venus seems … unlikely!