AeroGav

A lot of my designs have a 5:1 ratio of liquid fuel to oxidizer, when you click on the resources tab to look at the totals. That is because I generally use 2 RAPIER and 1 nuke for propulsion. At the point where I switch over to closed cycle mode, 40% of the liquid fuel is gone. The next 20% gets burned with the oxidizer in the RAPIERS, and the rest is used by the LV-N to complete orbital insertion and for interplanetary travel. Incidentally, when i was trying to optimise my flight profile i discovered that the initial subsonic fuel uses very little fuel however it is flown. However, the acceleration to mach 3 and climb to 20k is another matter. When your Rapiers get up on the power band and start boosting like crazy, it doesn't come for free i've found. Above 20km, their thrust and fuel consumption die off together. However, be aware that holding the nose down to try squeeze out that last 100 or 200 m/sec from air breathing node can get costly. Each design has a different natural top speed. I built an IRSU mining ship for Minmus, and wasted a ton by trying to force it to 1500/1600 m/s. Eventually realised this design cannot go above 1400 in level flight. My usual rides have quite generous wing area and only moderate thrust-weight ratio, but are pretty clean aerodynamically and are intended for bringing a small scientific payload a long way, rather than a large mass barely to orbit. I

I tend to fly a particular AoA rather than particular pitch angle - AoA being the difference between the orange -W- symbol and the yellow prograde marker. AoA below target, more back pressure on stick, above target, less back stick. Airspeed comes out at whatever it comes out at, based on altitude and weight. I try to avoid the sound barrier however, and will pitch up to 10 AoA to postpone exceeding 240 as long as possible,then pitch down to 2 AoA to accelerate through to 380+ ASAP. Pitch angle will vary with TWR and AoA, but I never pay any attention to it. I only target AoA. Good to know what the optimums are, OP ! Going hands off, with SAS and trim, I've noticed that my airplanes also tend towards a constant AoA, but the flight path is **NOT** constant, settling into a gentle phugoid oscillation with a period of about a minute. Real aircraft do that too, so it's a win for the game's physics.

Also, something which the tutorials fail to mention is that yaw instability causes roll instability. Make sure you have a large enough tail fin, far enough aft of the CG. This is an issue on canard designs, which often have long noses but short tails.

To do a tanker, it'd have to be able to fly from the KSC, out to wherever the space plane landed (potentially, the other side of the world), and have enough juice left to refuel the spaceplane with enough to get back to the space centre and have enough for itself. Sounds like a challenge, I'm going to try it ! The space plane itself is not a small aircraft. As for the IRSU idea, that's definitely something i'll do, but I don't have that tech yet. The problem with playing this way, is that it turns everything into such a marathon. 15 minutes - getting the space plane out of the atmosphere , separating the rocket stage, stabilizing it's orbit. 20-25 minutes - re-entry of spaceplane, glide and landing. 90 - minutes - fly subsonic tanker to the space plane. 25-30 minutes - fly space plane home at high altitude and mach 2 90 minutes - fly the tanker subsonically back to KSC At this point, you discover you forgot to put an antenna on your probe stage, and need to redo the mission. For the above reason, i think i'll look at Kerbinside, failing that, Davon. The problem is starting to solve itself as my space planes get more capable. I built a type II with 4 long cargo bays and it flew alright, but the rocket stage within wobbled all over the place, fighting it to Duna and back left me with grey hairs. So, I'm going to concentrate on 3 cargo bays max, bring a little more fuselage tanks and maybe take the first stage all the way to orbit. As for Mun / Minmus, I might just bring the whole plane next time.

My setup consisted of quite a few items jettisoned from the nose or tail of my spaceplanes. Took a lot of docking to put together. The mining section consisted of a drill bit, a small ore storage tank, and the IRSU converter. This always stays on the surface. The bit that flies, is a mk2 cockpit, mk 2 fuselage (the fuel tank) and nuclear engine. Docking on the surface is easy. Rendez-vous in orbit is a little tedious to do 5 times over. Worse, I flew a load of empty fuel tanks up to orbit, the idea being i could have a massive fuel depot ready for a customer, and fly a mk2 fuselage worth of fuel up to it every time the IRSU converter got it filled up. The problem is , the orbital fuel depot was too long and this, and wobbled and spun like crazy. This made docking with it even more of a chore. Another option, if I don't want to go the Elite route of simply having my deep space exploration vehicles carry their own drill bit and IRSU converter (why not, it's still lighter than fuel for the return leg, i;d bet) would be to simply land all my deep space vehicles on minmus and taxy up to the mining station for fuelling. Put a big load of fuel tanks there and fill in one go. Minmus has very low gravity, i hear space planes can simply land on the flatter section horizontally like a runway. Make a deorbit burn so you'll come slowly down onto the flat bit, then rotate to a landing attitude and the sturdy landing gear will take care of the rest.

Something I feel is missing from the stock parts are air breathing nuclear engines. I'm a relative newbie and unwilling to take the easy technobabble solution to problems, but i don't see why a version of the LV-N that can also use intake air would be beyond Kerbin technology. It would need a turbine compression stage to compress the intake air, and a power turbine in the exhaust stream to drive that. As a result, it would be subject to the same decline in thrust with speed and altitude as a turboramjet - the Rapier engine chills the intake air with the fuel stream before it enters the combustion chambers, which enables it to operate faster and higher, unfortunately a nuclear turboramjet won't have that. You could also swap the nozzle for an aerospike. The stock LV-N performs well in a vacuum, but suffers more thrust loss due to atmosphere than any other rocket - a factor of 6 or something crazy like that. Aerospikes are not quite as good in a vacuum, but perform a hell of a lot better at surface pressure. They are also much less draggy. All in all, such an engine will not do much more than allow indefinite level flight at low altitude , due to low TWR , 1950s nuclear powered aircraft concepts still required jet engines to get off the runway. But at least your LVN's aren't total passengers below 20k, or wasting fuel unnecessarily. Taking things one step further, liquid core nuclear engines. Technologically, I don't see any reason why we couldn't build one now, but you could never use such a thing on earth due to the intensely radioactive exhaust. Should have around three times the TWR and ISP of the solid core nuclear thermal engine however.

I did it in my first sandbox game (well, a refuelling point on Minmus for my spaceplanes to be exact). I was concerned about how long it takes to mine and convert, but actually, the mining and conversion continues when you're flying another spacecraft, so long as you're not in time acceleration mode. This meant that whenever i switched back to the thing i'd invariably find either the ore storage or fuel storage to be full. Huzzah. But, I really grew to hate all the docking operations. The Minmus fuel truck only carried 800 fuel at a time from the surface to orbit, which meant at least 5 trips and 10 docking operations (one on surface, one in orbit) to refuel one mk2 spaceplane. In my current career game, I'm planning another refuelling base but I need to use a larger tanker, which is still easy to dock. Or , shall I just build a mk3 spaceplane and have it carry it's own IRSU and drill bit out to Leythe or wherever and just refuel itself, like in the 8 bit version of Elite? Go fly another plane while one is refuelling/waiting for the launch window to come back to Kerbin and be done with it.

I struggled for a long time with a spaceplane design with yaw instability. Added tailfins wherever I could behind the CG, on the engine pods, at the wing tips, above and below the wing, and of course on the tail itself. Could never get it under control. Then after a crash i noticed a message about engine exhaust from the wing root mounted jets damaging the tailplane, at the start of the destruction log. Moved the tailplanes up a bit, out of the efflux. Suddenly the yaw instability is gone. Why would the jets impinging, symetrically, on the tailplane, result in a yaw problem? A pitch problem, perhaps, but yaw? Anyway , this is why you don't want stuff sitting in the jetwash. Even if it never gets hot enough to explode.

I dont know if the scripting allows such a check, but i was planning to make it so you can only refuel when the body you have landed on is Kerbin. And only with liquid fuel. I'm working around this ATM by landing, then enabling the infinite fuel cheat to take off again and fly back to the space centre, abstracting the recovery flight from a downrange airbase a sub orbital launcher aircraft would have to make. Obviously, if i damage the plane putting it down, you're looking at an almost total loss - which is also realistic. My sandbox aircraft with Rapiers and LV-Ns can do SSTO with good payload and IRSU, but I hit upon this idea to make the Whiplash planes work better. The wings, control surfaces, airbreathing engines, jet fuel tanks, and landing gear aren't useful above 40km, so if you can only lift so much rocket fuel, use it on the upper stage. Bee-lining High Altitude Flight, my first proper spaceplane still had fixed gear (which tended to burn off), the "swivel" rocket, and 30 parts limit. I still managed to launch probes with it - the jets were pod mounted, i moved the tailfins to the wingtips, and put a stack decoupler on the rear half of the fuselage. At 40km up, I'd jettison the tail, which contained the rocket motor, rocket fuel tank and probe stuff, fly that to orbit, and land the rest of the plane. Unfortunately that design became unstable when scaled up, so my current ride has an internal cargo bay most of the length of the fuselage (3 large type 2 cargo bays) which contains the upper stage. It's taken Jeb to the Mún, to Minmus, and sent probes out to Jool. The manned upper stages have small wings and parachutes (heatshields are for wimps!) and re-enter with everything attached. When I make a mission to Minmus, everything that leaves the runway comes back eventually.

Since my primary spaceplane takes so long to get up, i have time to click on stuff. The LVN is already producing near-vacuum ISP at 22km, when i generally start it. Together with the dregs of airbreathing that gets us to 1600ms and 27k at flameout. 440 oxidizer only gets me another 8km and maybe +150 m/s. But the drag is low enough at that altitude, for the LVN to do the rest.

I'm a spaceplane guy, so probably not the best help with regard to rockets. I too found that early game, how fast and how high is limited by what you can bring someone back alive from , not what the rocket itself can do. SAS is artificial stability system. It makes control inputs to try and counteract any deviation from the straight and narrow your vehicle may do. It's not actually a tech - because your crew contains a Pilot, the option is available. However, it can only correct using the same control surfaces that you yourself have - a sufficiently skilled player flies just as well without it. And here in lies the rub. You don't have any control surfaces. Those fins are not steerable, nor does the rocket motor have thrust gimballing. The only steering you have is the reaction wheel torque from the crew capsule. I guess you could outfit your vehicle with multiple crew modules for more "steering", but it's not ideal. Incidentally, surely the rocket is going slowly the moment it runs out of upward momentum and stops going up? Or are you well out of the atmosphere at this point ? In which case, you'll just have to earn science with smaller rockets for now. Or, is your rocket turning over horizontal shortly after launch, and developing a very high horizontal velocity which never goes away till you smack the ground? There's plenty of science to be had from little rockets anyway. When I got steerable fins, I basically used a combo of winglets and fins to pull the vehicle out of it's vertical dive once re-entry was complete. They'd slow it to 100-150 or so, and a 30 deg dive, wherupon the parachute was safe to deploy.

Well here I am in my Career game. I love space planes, in fact I'm terrible at rockets, so here I am trying to do stuff with aircraft as much as possible. I've unlocked the Whiplash turboramjet, but I can't yet get a decent payload all the way to orbit. So, my space planes are sub orbital craft, which launch the rocket upper stage at high altitude, which i have time to stabilize the orbit of, before switching back the plane which i guide in for landing. The problem is, the plane tends to come down the other side of the world from the space centre. Sub orbital flights you know, hazard of the job. Hypersonic 180 degree turns are not advisable, by the time i've slowed enough to make the turn, i'm so far downrange there's no way to get back on remaining fuel. The problem is that you end up recovering only 25% of the cost of the plane for landing it so far away from the space centre, even though you put it down completely intact and all it needs is a tank of gas and it's good to go again. Use a rocket instead, get nothing back, and it works out cheaper because the launch cost is less One answer would be to put airports all over Kerbin , but as a simpler workaround, why not make it possible to fill up on Liquid Fuel only any time you are stopped on the surface of Kerbin. Bringing over a tanker of jet fuel to a plane that's landed in a field so it can take off again is no big deal, after all the stuff's pretty ubiquitous, filling up solid motors, loading LOX or Hypergolics probably requires a space centre.. So, that way I can refuel my space plane on the ground and fly it back to the space centre before hitting the "recover vessel" button. A lot of leg work, and something you'd rather have abstracted out, but fairly realistic for a sub-orbital launcher.

I'm just trying to get my head around the theory behind all this. My regular spaceplane "creeps up", basically goes on a top speed run at 18,000-20,000m , then i milk the nose up trying to stay airbreathing as long as possible getting all the horizontal speed i can. 2 RAPIERS and a Nuke on a 35 ton launch weight. The "other woman" is much more minimalist, couple of "whiplash" bolted to a light 13 ton airframe. What I find myself doing is getting into a zoom climb after punching through the sound barrier around 10,000m, accelerating to 900m/s by 20km despite climbing at a 60 deg angle, loosing power rapidly thereafter but still coasting to 40k. I'm trying to work out if there's anything special about the zoom climb vs creeper method... is my theorycrafting all hogwash, if not, is it only applicable to very high thrust-weight designs? 1. At 14km and 800 m/s your engines have an enormous surplus of power over drag. 2. Used to accelerate horizontally, drag rises exponentially and you're going past the max power speed of your engine - the faster you go , the less thrust you have. 3. So, use the surplus thrust to build momentum in the vertical direction instead. Is there anything special about upward momentum? Is it better to be climbing at 45 deg at 800 m/s when your whiplash shut down at 24km, or 1150 m/s but barely climbing at all? I'm expecting the answer to be "no", 800m/s in a 45 degree climb is the same kinetic energy as 800 m/s horizontal. Although once I go anaerobic, I normally pitch up 10 deg AoA to try get out of the draggy air sooner, generating the lift to create the g forces for this pull up manouvre is something you'd bank at lower altitudes when your airbreathing engines still have lots of thrust, if you were using the zoomer method. Incidentally, my sandbox mk 2 gets to 27km and 1600 m/s before switching to closed cycle. She gets to orbit with only the oxidiser that comes with a pair of short mk 2 - mk 1 adapters (440 oxy?). For a pure LEO truck, it'd make sense to carry more oxidiser and leave off the LV-N, but the main mission of this one is single stage to a Minmus refuelling station, whereupon it can swallow 3000 units of liquid fuel and go basically anywhere.

I'm not sure a space shuttle replica would be a good solution, but the mk3 spaceplane I built out of stock parts in sandbox mode is great. Easy to fly, reusable, good mass fraction, and very safe. The problem(s) with space planes 1. Attaching loads is much harder. Even in a type 3, can be awkward getting stuff in the cargo bay. Tried making an aircraft with twin tailbooms, leaving a place to attach a load with fairing at the end of the mid fuselage, but stuff doesn't want to snap in. 2. Takes longer to get to orbit. It's a lot of fun, but yeah with a rocket it's over much sooner, one way or another. 3. In career mode, aircraft techs are too far away. Retractable undercarraige came in the 1920s, before the Apollo program. The first kind of jet engine was the turbojet, which is actually better at high speed/altitude than the turbofan, went to mach 2.8 on the mig-25. The SR71 blackbird was a turboramjet, 1960s/70s tech, top speed/altitude limited by skin heating. 4. In career mode, there are no airports other than the KSC. Many of my early space planes were sub-orbital, first stages for the rocket interplanetary vehicle. They'd land off-airport on the opposite side of the world from the space centre, so i'd only recover 25% of the cost of the plane , even though it is completely intact and just needs topping up with jet fuel to come home. Would actually work out cheaper to use disposable rockets :-(

Damn that's a bit lame. At least the optimum should be a wing that gives around 5 degrees alpha to be somewhat closer to real world aero. Obviously how you'd size it would still depend on what flight reigime you want to perform best in but hey.. During the early rocket powered part of the ascent though, i'd thought it's still better to have a larger wing at low AoA than a small one at high AoA because you'll be thrusting closer to prograde. As regards using incidence, a mk2 fuselage also makes lift so you want that at similar angle to wings as well?

Rocket guys care a lot about thrust-weight ratio, but space planes it's not so important, just takes longer to get there and gives you more time to think. What planes it's all about drag vs thrust. So long as thrust wins, you're getting closer to space with every second that passes. I've heard that bicouplers are very draggy, so i'd be tempted to ditch that and use only a single rocket. Once you're in rocket mode the atmosphere is already very thin and a combination of orbital effect and residual lift are nullifying gravity. However i'd also use an inline cockpit and put an intake on the front - since you've no option but to take the drag hit from a fuselage and two nacelles, might as well get more air from the fuse. Finally, I like more wing. In this game, wing surfaces do not create parasite drag, only lift induced drag - ie, drag is proportional to angle of attack. More wing = lower alpha, therefore less drag. I pack as much wing as aesthetic considerations, structural rigidity and aerodynamic stability allow. The profile i use - 1. Try to maintain around 5 degrees angle of attack during climb, where drag is lowest in most aircraft. 2. As we climb, the airspeed required to maintain 5deg will increase. When it reaches 240 i start pitching up to stop it rising more, since you're nearing the sound barrier and drag is high in that region. 3. At some point, my plane will stop gaining altitude or airspeed. Or i'll start exceeding 10 deg AoA, which is where drag gets too high for my liking. Or i find myself running out of pitch authority, with huge red lines coming from stalled control surfaces. At this point crossing the sound barrier is the lesser of two evils. 4. I let my AoA drop to 5 deg or less to accelerate through the high drag zone as fast as possible. 430 m/sec is in the clear, you're over the drag spike. I start a gentle pull-up to break out of the dive at around 350 however. 5. There is probably no time for this unless you have a really low TWR plane. I pitch up to avoid exceeding 500 m/s below 16,000 when drag starts to rise again after clearing sound barrier. really there's no time though, because 6. 18 -19k is best altitude for your top speed run. I need to start pitching down at 16k so not to bust this. 7. At 18-20k, accelerate to highest poss speed in level flight, then start a slow climb. 8. At some intake air value, i switch on the rockets rather than let my hard won momentum dissipate. 9. I pitch up to 10 AoA until 35-40k when i stop getting signnifant lift, then prograde. Get what you can from those wings while you still have a bit of atmosphere, and out of the soupy stuff where your rocket is less efficient. 10. the final part of the journey is now under little or no time pressure.

Thanks for the replies. I got a 4 day work shift coming up so won't get to look at any of this for a few days unfortunately. Yeah, I'd like to give myself more starting science especially in the aircraft side of things , but give myself a tight budget where i'm forced to bring everything back and cut down on unnecessary launches. In my career game, i've beelined airplane tech hard, as you might expect, yet despite being able to put men in orbit (1960s tech) , my airplanes still don't have retractable undercarriage (1920s tech), and am stuck with jet engines that won't exceed 8000m / 240 m/s (think we managed to beat that in 1940s). The Wheesley's seem to have been nerfed in the last few updates.

I bought KSP two weeks ago and am absolutely loving it, spent virtually every free minute of free time on it so far. I've got two different games running however, which reflects the dilemma I find myself in. In my Sandbox game, I've been building, testing and flying space planes, which is the main thing I love about this game (not that there aren't other attractions!). I've been using those spaceplanes to set up an In Situ Resource Utilization base on Minimus, which will then allow my aircraft and probes to reach the rest of the solar system with ease. It's taken ten flights of my MK2 space plane to put all the pieces of this base, the orbital resource scanner and an ion thruster space tug up in mid Kerbin orbit, and i'm just finishing off docking the pieces of the Minimus IRSU rover together, and the boondoggle is almost ready to set off. Assuming it all goes my way, I'll achieved exploration of the Kerbol system with reusable vehicles only and without having to bring interplanetary fuel up from ground level. Should be good for the budget, in the long term. The problem with this game mode however, is that being sandbox I already have unlimited funds and when i actually reach these outer worlds, i can fly around a bit and see what they look like, but ultimately won't be able to do any science on them (will i?) and won't have anything to spend the points on anyway. For this reason, I started a career mode game, but it's taking so long to tech up, furthermore, my beloved space planes are right at the far end of it. By the time i'm able to do what i have been doing in Sandbox, i'll have had to have explored the entire system anyway, just to earn enough blue points. Career mode is all about rockets, but i don't find them as interesting and besides , i'm horrible at both building and flying them. Most attempts, even with stock vehicles, end in a huge fireball and KIA. Is there a mod or game mode where you are strictly limited for reputation and funds, already have the tech tree open, or some mod that adds near-future sci-fi items i can work towards once i cheat my way to supersonic/hypersonic aircraft tech?