AeroGav

After this MK 2 - I started a career game with Kerbal Construction Time. I'd just unlocked the Panther, so set about building my first Panther/Terrier ship. Now, I can just barely get a Juno/Terrier in orbit, if I drop all 14 Juno engines when they flame out. Trouble is , you can build a rocket for that sort of money, with more delta v margin. My previous Panther offerings can get to orbit without shedding parts, and more delta v margin, but still not enough to go anywhere. So I got thinking. Launch mass 14 T. Minus the airbreathing engines and fuel, we have a dry mass of just 5T. My previous designs went with 2 Panthers and a Terrier, because it's nice and symmetrical and you can eke the last dregs out of the Panthers after firing up the rocket. But that's an extra 2.4 tonnes of jet engines you're carrying from 20km/Mach 2.5 to 70km Mach 7. 50% more dry mass that rocket fuel load has to bring up to orbit. Is there any way we can only bring one? Well, that means off axis thrust/asymmetric propulsion unless you just mount the Panther behind the Terrier. Now we could cheat and use clipping but i'll be honest and go with staging instead. So, we're back to throwing away engines again, fortunately the Panther isn't all that expensive and it's only the one of them. Loosing two feels careless. However, all my previous engine droppers shed their motors from wing mounted pods exactly over the CG, so the loss of mass does not cause her to undergo convulsions. Surely shedding an engine from the rear of the fuselage is going to make the plane suddenly nose heavy? Enter the Firefly - That plank wing generates enough lift aft of CG to exactly offset the mass of the engine. It is shed along with the rear landing gears, engine nacelle, which serves as an intake and LF tank for the jet. Do be mindful of the fact that in a mission abort, this section becomes a cruise missile and should on no account be aimed at the VAB, no matter how severe inter service rivalry gets. On rocket power. The beta version of this craft reached orbit with 800 m/s remaining. Good, but not enough to do much. The residual fuel quantity was actually comparable to the rocket division's offerings, the problem was all the extra mass it would need to drag up to Minmus. So, I had the idea to mount an inline cockpit and one fuel tank immediately in front of the Terrier, and use docking ports to separate this from the rest of the airframe in low orbit. Intact airframe in low orbit. All that dead weight means we won't go far on 100 LF Undocking the "upper stage" almost doubles our Delta V - unfortunately, I need to offset the tail booms a bit, they're snagging on my solar panels. After finally wriggling free ... Next question - would i simply be better off designing an air launch to orbit platform? Dropping the upper stage at 20km and mach 2.7, I may be able to get us sub orbital before the airplane launcher crashes

I logged some data from one of my space plane ascents, and took some screenshots with aerodynamic forces display (F12) enabled. There is definitely a max speed you can do at each altitude , if you get too fast too low heat builds up SEVERELY. At lower altitudes, aerodynamic drag losses become huge long before anything threatens to melt, you see huge red drag lines on the aero debug. But above 20km you can melt your ship without hardly experiencing any drag. I guess what's happening is, at lower altitudes, yes there is frictional heating , from large quantities of air moving at lower speed, but there is also a lot of cold air flowing over the part cooling it down. If you're going twice as fast in air half as thick, you might have the same overall drag force + friction, but there is less air flow to take the heat away. Also ambient air temperature starts going up in the stratosphere. Mach 3.7 @ 23km - plenty of lift on my generously winged design. No drag and thermal is ok (38%) Mach 4 @ 26.5km - faster but also higher, only 40% max temperature. Still no drag. 29KM and Mach 5 UH OH. Thermal has shot up to 86%. You can see i added some UP on the pitch trim in response. Even though we came close to blowing up, drag is still negligible. That instinctive pull saved our bacon. 38km and mach 5.5 but temperature is dropping below 60% and we'll soon be shaking hands with Jesus. You can see that lift is starting to fade, but the centrifugal forces from being near orbital velocity are supporting most of our weight now anyhow. Edit - bear in mind this is a pretty slick airplane, and at greater pitch angles you would see big red drag lines even at this altitude. That's why it has so much wing area, so that it does not need large pitch angles to get lift above 20km, and therefore 2 NERVs are able to slowly accelerate it.

I'm more of an airplane/spaceplane person but i have built some rockets in early career mode and making something that doesn't lawn dart on re-entry is a problem lots of folks run into, when trying to bring back more than just a capsule. Being an airplane person, i solved this with fins, so i can steer it off the terminal dive it likes to get into and slow down so you can get the chutes open safely. https://onedrive.live.com/redir?resid=7003A8806D8A6B2C!716&authkey=!AK7nQaujPuAKeUU&ithint=file%2ccraft I tried pretty hard to keep the ascent stage small and cheap, my own career games i'd probably have used side by side boosters on the lower stage, but that's more cost mass and drag. I have kerbal joint reinforcement installed i hope it doesn't flop around too much.. Bill of Materials upper stage - nose cone heat shield ft200 fuel tank ft400 fuel tank 4 ox-stat solar panels 2 radial mount parachutes mk1 passenger cabin ( 2 of) 4 steerable fins mk1 inline cockpit terrier engine lower stage 3 ft400 tanks swivel engine 3 steerable fins ZOMG booster stage 6 Fleas EDIT - upper stage in flight. One is reminded of the scene from the Austin Powers movie... Here's a 2 passenger variant in one of my career games, just before popping the chutes. Body and fin lift mean we can slow down from even the steepest sub orbital trajectory to a safe parachute velocity.

I believe that spaceplanes should err much more on the side of stability than fighters/aerobatic jets. Even a momentary upset on an SSTO costs so much height, velocity and fuel you're going to have to scrub the mission and miss the launch window. And then you've got the huge quantities of fuel burning off and cargo getting unloaded... The problem I faced when going for stability is that large forces are needed to hold the nose up in straight and level flight. Most of the stock control surfaces max out at 30 degrees deflection, and when operating at large angles they create more drag than the rest of the craft put together. Adding more control surfaces means more lift up front so you'll be back in an unstable plane scenario again. Fortunately the advanced canard limits deflection angles to just 10, so you can have a super stable, stall proof plane without the drag killing you. The problem is they are tiny and the limited deflection angle makes them weaker still, I had to fit 4 pairs to my mk 2 and like i say, that's only enough to reach 15 degrees AoA during a landing flare (any more would be pointless & cause a tail strike). The drawback, is that the nose of my plane looks like a UHF aerial. Well, handsome is as handsome does, they say.

There's a few little known/poorly understood factors that explain why we need a further forward CG than the indicators in SPH indicate. One I recently heard of is body lift, which holds up better at post stall angles than wing lift. Since you usually have more body ahead of CG than aft of it, because of the heavy engines at the back, this can become a destabilizing factor. My airplane can only angle the nose 15 degrees away from prograde in the atmosphere. At the start of re-entry, the reaction wheels can hold greater angles but when the heating is getting strong the aerodynamics kick in and force the nose down anyway. Like I say you shouldn't need extreme angles to come in from a low kerbin orbit. I have blown my plane up multiple times aerobraking in the Jool system but that was due to part skin temperature not core temperature, meaning it all happens in less than 5 seconds and nose angle wouldn't have time to make any difference, other than which part explodes first.

First off, I would double check your centre of gravity when unloaded - no cargo and fuel - to see if your plane is just unstable, period. You should be able to hold 30 degree angle of attack without flipping, in fact my spaceplanes have trouble holding the nose that far off prograde due to excessive stability. You can see that the layout avoids large shifts in CG Heavy nuke engines either side of the CG One cargo bay in front of CG, one behind it One engine at rear of fuselage, balanced by the weight of the cockpit The fuel is stored in the wings, in other words, the exact place where the lift is generated, and is thus cg-neutral Thread (including download link) for this airplane here - Secondly, Mark 3 aircraft have higher temperature tolerance than type 2s and there is no way you should need to hold that much nose angle to avoid burnup. Coming back direct from Minmus I might set a 42km periapse and 10 degree pitch angle. If I'm undershooting the space centre, I lower the nose to 5 degrees where lift/drag ratio is better, if i'm overshooting i pitch up a bit to make more drag and if too hot i also pitch up because that keeps me higher in the atmosphere. Having lots and lots of wing helps re-entry on my design because it generates enough lift to stay out of the thick atmosphere till it's slowed right down. In addition, you can probably take a few measures in case the worst happens - use an inline cockpit so it's not right at the front and the first to blow attach a heat shield to the front of the cockpit attach an aerodynamic nose cone to front of heat shield attach a radial chute to cockpit (optional) Now, in a normal re-entry, the heat shield is covered by the nose cone and never ablates. But if you screw up the nose cone burns off , exposing the shield, which in turn occludes parts behind it in the fuselage stack - it will stop these from heating. Your ship will need a new nose cone and suffer more drag in atmospheric flight, but the crew live. If you really messed up , the wings or canards aren't covered by the shield and can still burn off. At this point you pop the chute and save the crew. Even an empty plane is a lot heavier than a capsule so you'll come down fast on that chute, but the good news is it can withstand a heck of a lot more impact than a flimsy capsule, especially with your gear down and the rear fuselage as crumple zone.

The Easter weekend gave me some time to play with my creation from a few posts ago. In that thread, I reckoned it could lift a light scientific payload to Minmus, and put a heavier payload eg. IRSU in orbit but not take it to Minmus. This weekend I thought I better show it could live up to those claims. First question, can you even fit an IRSU setup in a MK2? Unfortunately I ran out of weekend to address any further questions, because this test flight took a bit longer than anticipated.. Well, I'd forgotten how much lighter the small converter and drill are than the big one. Yep, their efficiency is awful. But, I was able to get all the way to Minmus with 400dV remaining - only 500 less than going up empty. This is only my third launch of this aircraft, so i guess my flying is still improving. Note, I'm still matching inclination of Minmus after reaching orbit. Could save a bit more if I knew how to time my launch and take off inclined, or burn direct to Minmus with no parking orbit. Of course, this is a bit of a "Spam in a can" setup. How can our kerbonauts tolerate such close confines for months years on end, without being romantically involved? And if they are romantically involved, some things must never be shared... i presume they must go on EVA every time one of them wants to use the bathroom. I'd give it half an hour before stepping outside , if i were you.... 400 spare delta V means I was able to get into a polar orbit and do a planetary survey before setting down. Once on terra firma, the slow rate of fuel production proved to be a non-issue due to the bug that makes solar panels continue to produce power on Minmus at nighttime. Just left it in time acceleration for a couple of Minmus days and we were full up again. Time to go home... or maybe not.. Keep this up, they'll give me an orange suit as well ! Mining on Duna was a lot harder work than on Minmus because the solar panels really do stop producing overnight. And unfortunately, the drill has to be manually restarted every time it shuts down for a lack of power, while the converter just picks up where it left off. Given that the process is bottlenecked by the drilling rate, that's a bind. After restarting my drill 30 times, I was quite glad to see the back of this place.. . As luck would have it, that Island is an ore hotspot. Unfortunately, it looks like this is the last stop on our tour. It appears we've been hit by the occlusion bug, I cannot use the NERVs because the game thinks they are stowed, unless i open the cargo bay. Opening the cargo bay in Laythe's atmosphere creates too much drag to exceed mach 1. We didn't have this problem on Duna and I can't seem to recreate this fault with the same craft down on Kerbin, but i'm at a loss to solve it on this one. Next week, it's time to verify this SSTOs cargo ability. The centre of lift is exactly between the two cargo bays, so i'm not anticipating any problems , but i've put together a little "upper stage" module to try it out - This one man exploration module has a mk 1 crew cabin so he doesn't have to spend the whole interplanetary leg in the lander can, which serves as the "command module". The ion engine cluster, with reaction wheel, battery, command chair, and small xenon tank, can be undocked from the rest of the craft and hopefully be light enough to land on ion power alone...

Actually that "beginner, tiny" engine, aka. Juno is better for speed and altitude than the Wheesley and Goliath. The first jet engines were pure turbojets, the Wheesley and Goliath are types of high bypass civil turbofans, which trade some of the turbojet's fast and high capability for better efficiency and static thrust. As you point out, the Juno IS tiny, so you need at least 10 to see what even a mark 1 cockpit vehicle can do. The Juno produces max thrust at mach 1.3, which coincides nicely with the fact this is where supersonic drag coefficient is at its lowest too. 0.85 to 1.2 mach is the high drag transonic region, and above mach 1.3 drag starts to go up again as you go faster and faster. Obviously subsonic has lowest drag of all, but that's not what we're about is it? I have built low tech spaceplanes with 12 Junos and 1 Terrier, for the lulz. Could generally get up to 1.3 mach and 12km on the jets before firing the rocket. Without the weight of the rocket and its fuel, you could probably fly a little higher on just the junos. Not high enough for any of the high altitude research missions unfortunately. **pps. these "spaceplanes" had no cargo and only barely made it to orbit. they also jettison their landing gear and dump the jet engine pods when they loose power, so not the most practical or re-usable. Agreed though, the Panther is streets ahead of anything you've seen before when you finally unlock it. If you're not making sustained flights at 18km and Mach 2.5, you're doing something wrong.

Troubleshooting help - press f12 for aerodynamic forces display. Look for the red arrows - drag - which is bad. also right click on your engine you can see it's thrust tail off with altitude. In Kerbal, jet engines have two modifier curves to their basic power level. Increasing altitude always results in less thrust, but the table in the config file determines what % of thrust it looses with each altitude. The other modifier is speed. Generally, thrust goes up with increasing speed, to a certain point, then tails off again. If you're new to aeroplanes it might be worth hitting google for "angle of attack", "lift:drag ratio", "parasite drag" and "lift induced drag", things that will help you eke the most performance from your plane. Generally plenty of wing area, if altitude is your goal. best lift : drag occurs at 2 degrees AoA, which requires lots of wing minimise frontal area, and the amount of radially attached parts there should be something pointy at the front and back end of your fuselages and nacelles - flat plate drag is awful, even on the back end ! tail planes or canards are just like wings. they too make a lot of drag at large deflection angles. I'm a fan of spamming Advanced Canards, because their max deflection angle is only 10 degrees instead of 30. You may need more than one pair to get enough control authority however. If your plane has centre of mass way too far forward this can also cause excessive drag from these surfaces.

I never figured out how to make a plane change before getting to orbit and i know it costs me a fair bit of delta V. How do you do this? Do you have to time your launch for the planets being lined up or can you just take off, set target, and fly north/south within the atmosphere in the same way you'd burn normal/anti normal when in orbit? The problem is , patched conics won't give you an AN or DN because you don't currently have an orbit to compare with the target?

Something that's bothered me for a while. Why are non-badass Kerbals scared so much? At the moment, the rule seems to be, look worried any time below 20km whenever an engine is running It kind of makes sense during rocket launches, which are always, impressive even when they go right. In my case, their concerns are justified most of the time. However, boosting away from a Minmus refuelling base to Jool also terrifies most of the Kerbals, even though we're 6km off the ground , on a steep upward escape trajectory. The risk here is not so much of crashing into something, rather that the craft never comes into contact with anything solid ever again. Ah well, if only i could get my head around orbital math. Worst of all is when flying aeroplanes and spaceplanes. Mine tend to be rather sedate, low TWR, large winged beasts with excessive stability and sluggish controls. Even my space planes don't go supersonic below 10km, and climb out at a rather shallow angle. I can't actually remember the last time I lost a crew member on one, though mission aborts and fails happen a great majority of the time. * Yet, despite the fact that we're 10km over the water, subsonic, wings level, slowly climbing and not on collision course with anything Bill looks like he needs his Mommy. On the other hand, we can be on a fatal plunge towards the ground in a space capsule where the chutes have failed, or about 2 seconds away from burning up in the re-entry heat, and everyone's happy because the craft isn't under acceleration. What gives ?

Thanks , but I get the feeling that if you'd built it, you'd have found a way to make her look good !

One - Nuclear turbojet engines for planetary bodies with atmosphere but no oxygen. Two - Support for Staged Airbreathing in career mode. Re-usable booster stages and air-launch to orbit are valid strategies to increase re-usability even if SSTO is currently beyond your tech level. There was a mod that saved the state of jettisoned stages allowing you to fly them back and potentially save them, but it no longer works with current KSP versions. Three - more runways please ! If you are using air launch to orbit, the parent aircraft often finds itself far from home, on a sub orbital zoom climb, and low on fuel. It often cannot return to the space centre and frequently less than half its value is recovered landing on the antipode.

https://onedrive.live.com/redir?resid=7003A8806D8A6B2C!713&authkey=!AKArjxC_7Z_h9kk&ithint=file%2ccraft Quick Overview Two long mark 2 cargo bays either side of CG to minimize loaded/unloaded CG shifting. Four pairs of Big S delta wings containing most of the fuel. Fuel also stored around CG with minimal shifts from full to empty. One Rapier engine. Two pod mounted Panthers serving as boosters at lower altitude – when jettisoned, this uncovers the NERV engines mounted in front of them on the same pods. Three Vernier lifting engines in the belly to assist horizontal take-off and landing in low gravity environments. Liquid Fuel Capacity 3360 Units. Oxidizer Capacity 440 Units. Fuelled but with empty cargo bay it has a take-off weight of 38 tonnes. Has very small ailerons which cause sluggish roll response. While this makes it easier to fly on keyboard, it does make lining up with runway at KSC tricky – recommended to land on the grass. Unusually, it’s a taildragger. Couldn’t get the layout to work any other way, sorry. Deal with it. Designed to be flown with Kerbal Joint Reinforcement mod and TAC Fuel Balancer. Staging Info Starts both Panthers in Dry mode and the Rapier. Jettisons the Panthers when they become useless. Starts up the NERV engines. Abort Button – Toggles Panther engines between Dry and Wet mode. The above graph shows my speed/altitude profile and the different power sources in use. Blue indicates where the Panthers were active in Dry mode. Red indicates afterburner use. The Rapier engine has the colour yellow on this chart, the nukes a nice radioactive green. What you'll notice - Up to 10km I'm gaining height faster than speed, and not attempting to pass the sound barrier. At 10km we nose down and use afterburner to get through the high drag transonic regime as fast as possible. Speed and altitude mainly increase together but comparatively small deviations from this trend, where speed increase is not matched by height gain, cause enormous increase in temperature. Pictures from Flight & flying tips Final result - parked on the greater flats with 900m/s remaining. Kerbal engineer only takes account of the fuel in the pre-coolers in its delta v, doesn't allow for the fuel in the wings which the nuke engines wouldn't be able to access without TacFuelBalancer or transferring manually. Design Rationale

This is valid if it leaves just a capsule and heat shield behind, but even without engine and tanks his vehicle is going to lawn dart. The problem with dropping the upper stage is that he'll have to move his steerable fins up the rocket if he's to have use of them in his hour of need, and that's going to mess with CG. Rearranging things to put fuel at the top, kerbals in the middle and upper stage engine at the bottom has a couple of advantages 1. re-entry heat is borne by the fuel tanks.. they will pop first to save the crew. 2. empty tanks are lighter than the kerbally bits, cg moves aft a bit and makes the design less lawn darty than it would otherwise be. Of course, you could decouple the terrier motor as well to take things further in that direction. Punching off the engine would be mad, because it is the only object behind the fins to offset the nose down moment posed by the weight of the crew cabins.

The game's modelling of aerodynamics and jet engine performance is heavily simplified, save the most egregious errors, there is only so much performance to be had. Chasing the perfect fuel mass ratio, engine combo, wing loading, and ascent profile has been an exercise in diminishing returns. That said, it's not that difficult to fly single stage to Minmus with a science payload, as these, whilst sometimes bulky (science jr, survey scanner) tend to be light. The problem comes with putting an IRSU refinery up there. This equipment is much heavier and i don't think it's possible to do without a refuel in low kerbin orbit, which is annoying because i hate flying rendez-vous and docking maneuvers. It's ironic because SSTOs make great IRSU ships, all those empty tanks they don't discard on the way up are perfect for stockpiling fuel. And a spaceplane with a scientific payload really comes into its own when you refuel it and fly on to Laythe, Duna etc. In terms of Delta V, spaceplanes are very efficient up to low orbit. Beyond that however, they're carrying a lot of dead weight in terms of air breathing engines, wings, control surfaces, intakes and (mostly empty) fuel tanks. If you don't plan to visit anything with an atmosphere, how about creating an upper stage for your SSTO? Have a nuke at the rear of the fuselage, with a liquid fuel tank, then crew cabin, then docking port in front of that. Once you're in orbit, transfer all your fuel to this tail section and detach it, free to explore the kerbin system with the rest of the airplane safely parked in orbit. In terms of a true deep space SSTO, this is my current best effort, first flew on Monday.. https://onedrive.live.com/redir?resid=7003A8806D8A6B2C!713&authkey=!AKArjxC_7Z_h9kk&ithint=file%2ccraft Quick Overview Two long mark 2 cargo bays either side of CG to minimize loaded/unloaded CG shifting. Four pairs of Big S delta wings containing most of the fuel. Fuel also stored around CG with minimal shifts from full to empty. One Rapier engine. Two pod mounted Panthers serving as boosters at lower altitude – when jettisoned, this uncovers the NERV engines mounted in front of them on the same pods. Three Vernier lifting engines in the belly to assist horizontal take-off and landing in low gravity environments. Liquid Fuel Capacity 3360 Units. Oxidizer Capacity 440 Units. Fuelled but with empty cargo bay it has a take-off weight of 38 tonnes. Has very small ailerons which cause sluggish roll response. While this makes it easier to fly on keyboard, it does make lining up with runway at KSC tricky – recommended to land on the grass. Unusually, it’s a taildragger. Couldn’t get the layout to work any other way, sorry. Deal with it. Designed to be flown with Kerbal Joint Reinforcement mod and TAC Fuel Balancer. Staging Info Starts both Panthers in Dry mode and the Rapier. Jettisons the Panthers when they become useless. Starts up the NERV engines. Abort Button – Toggles Panther engines between Dry and Wet mode. The above graph shows my speed/altitude profile and the different power sources in use. Blue indicates where the Panthers were active in Dry mode. Red indicates afterburner use. The Rapier engine has the colour yellow on this chart, the nukes a nice radioactive green. What you'll notice - Up to 10km I'm gaining height faster than speed, and not attempting to pass the sound barrier. At 10km we nose down and use afterburner to get through the high drag transonic regime as fast as possible. Speed and altitude mainly increase together but comparatively small deviations from this trend, where speed increase is not matched by height gain, cause enormous increase in temperature. Pictures from Flight & flying tips Final result - parked on the greater flats with 900m/s remaining. Kerbal engineer only takes account of the fuel in the pre-coolers in its delta v, doesn't allow for the fuel in the wings which the nuke engines wouldn't be able to access without TacFuelBalancer or transferring manually. Design Rationale

To be fair, my latest SSTO does OK on a LF only launch, though this was a test flight with empty cargo bay. We reached Minmus with 900 Delta V remaining. A light scientific payload probably wouldn't mess with the launch profile too much, indeed it would have to be light in order to still have the Delta V to make it to Minmus. If I decided to use this aircraft to fly a denser payload to low kerbin orbit, I could offload some fuel to keep the overall wing loading down. I could also fill the oxidizer tanks to capacity (on this flight, they only contained a small amount to power the Vernier lifting engines for Minmus landing) for a small additional boost. 26.5km and Mach 4. The Rapier has lost 2/3 of the thrust it had at 24.5km, which was the altitude at which it no longer made enough thrust to continue climbing. For this reason, adding another Rapier to gain a kilometre or two of airbreathing ceiling doesn't seem worth the penalty of another 2tons dead weight out of the atmosphere. Mach 4 at 28km. Unfortunately we've run out of lift and will be stuck at this altitude for a little while. Notice that in the last 1.5km altitude our Rapier output halved again. Mach 5 and 29km. For the past minute we stagnated at this altitude while the heat built up. 86.6% of Critical temperature, this is the hottest the airframe got in this mission. When she finally starts climbing again and the temperature trends down, I breathe a big sigh of relief. Mach 5.5 @ 38km. Going up.. Nearing 42km and Mach 6 30 seconds later we're at Mach 6.5 and 45km, but the real thing to notice is our Apoapse, which has shot from 45km to 61.4km. In another 10 seconds it's out of the atmosphere completely - time for MECO

I build oxidizer-free SSTOs with Rapier/NERV engine combo and plenty of Big-S delta wings. Getting up to the Rapier ceiling is the easy part, what sorts out men from boys is the ability to progress from there to orbit with just the meagre 60kn off each NERV engine. So long as your thrust exceeds total drag, you're getting closer to orbit with every passing second. With the stock aerodynamic model, optimum lift:drag ratio occurs at 2 degrees angle of attack at subsonic speeds , rising to 5 degrees as you approach orbital velocity. The problem is that at 30km+, the air is VERY thin and flying the optimum angle of attack for lift/drag ratio can result in stuff overheating from being too fast, too low, for too long. The limiting factor for me, when i add too much cargo, is that i run into a dilemma - not exceed 5 degrees angle of attack, and blow up. OR, pitch up to 10 degrees and be higher up, and cooler, for a given mach number. But, my drag is then too much at this increased alpha to gain speed, and i gradually fall back down into the airbreathing reigime again.

Like I said, a single Terrier is plenty powerful enough for an LFO engine. Your thrust doesn't need to equal your weight because you are an airplane - at optimum angle of attack (2deg) you're getting a lift/drag ratio of 20:1. So long as you don't have weight equal to more than 20 times your thrust in other words, it is possible to climb. I've done a very low tech space plane before with 10 Junos and 1 terrier. Just barely scrapes into orbit. I jettison the landing gear after takeoff, jettison the junos when they flame out and ditch it in the water near KSC on return. And yes i'm also attaching tail cones to the front and rear nodes of the fuselage then offsetting them so the engine can still exhaust, to minimise drag. Re intake spam - please don't , that's just extra weight and drag since 1.05 or even earlier. There's a config file in the game directory for each engine that specifies how rapidly thrust tails off with increasing altitude and there is nothing you can do about this. It also describes the flameout altitude which again is fixed, and also how quickly thrust is gained with increasing speed, what speed peak thrust is reached and then how quickly power tails off as you go still faster. The Juno is actually the best high speed engine till you get the Panther, it maxes out at 1.3mach and looses thrust more slowly than the Goliath and Wheesly as height is gained, but the downside is it's less efficient. And tiny. If you do have insufficient intakes for the number of engines, this manifests as the engine cutting out and restarting multiple times per second (spluttering/surging) possibly with different engines on different sides of the vehicle cutting in and out at different times, causing a snaking/weaving motion. Unmistakeable if it happens, but if it's not then there's nothing to be gained by more intakes. edit - yes there are 14 engines on the first pic, but it didn't help me get any higher than with 10 or 12. Call that an unsuccesful variant.

I ran into this problem too, especially on the "take tourists on suborbital flight" missions where you come in very steep. If you can put aerodynamic surfaces on, you can fly a positive angle of attack and generate body lift , and also drag. The problem is that in a conventional rocket layout, fins on the crew re-entry vehicle will be right at the top of the rocket, making the complete launch vehicle aerodynamically unstable. I got my fins lower down in the vehicle by putting the upper stage fuel tanks above the kerbally bits in the stack. The fins are therefore about halfway up the complete launchpad assembly, close to the CG, and can be overcome by more fins on the very bottom of the lower stage. Instead of putting everything in line I suppose i could have made the lower stage in the form of two side by side boosters strapped to the upper, but there would be increased drag from the extra frontal area. The inline design was plenty stable as it was, needed a good bit of nudging to gravity turn.

In Kerbal, unmodded? Or airshow footage? There's several things that can be confused though when referring to lateral maneuvers - 1) Roll (and pitch) rate - how long to get into the turn, and how long between yanking full back stick and hitting max G load 2) Instantaneous turn rate, degrees per second of heading change 3) Sustained turn rate 4) Off Axis manuevres - where the turn rate doesnt increase but the angle of attack increases enough to point a little more at the target Turn rate in terms of degrees per second, is determined by two things - Speed, and G - loading. Going faster slows the turn rate, pulling more Gs increases it. In real life, G load is limited to about 9 by human tolerance. So, a good fighter plane is able to sustain a 9g turn over as wide a range of speeds and altitudes as possible. Maximum turn rate occurs at the lowest speed which you can generate enough lift to make 9g at. More wing might let you do this down to slower speeds, but could harm straight line speed. More wing also allows you to pull max g at higher altitudes in thinner air. I'm not sure how things are with the latest generation of fighters, but i know that previous ones had a separate "instantaneous turn rate" to their "sustained turn rate". When pulling up to maximum angle of attack they generate so much drag the plane loses speed even on full afterburner, and within a few seconds it is going to slowly to maintain 9g any more. So, being able to turn at maximum rate and not loose airspeed (unless you really want to, but usually it's better to do an S turn or vertical manuever if overshooting) is another thing good fighters should be able to do - i think it's called "energy manuverability"

In the real world, leading edge high lift devices delay onset of the stall to 25-30 degrees (Kerbal seems to already factor this in). Delta wings have a very high stalling angle, and leading edge root extensions (strakes) like no the F-18 hornet have this effect. Back to Kerbal, no. Stock aerodynamics use the same curve for Angle of Attack vs Lift and Drag for all types of wing, all stall at 30 degrees. Ferram Aerospace has much more elaborate drag modelling but all my designs seem to stall at similar angles, and leading edge slats/droops as used by airliners, have no effect on the stalling angle. In fact they generate negative lift if you angle them down like in real life, to get extra lift you need to angle them upwards The thing is, drag increases faster than lift above 5 degrees AoA and at 20+ it's going to be horrific. Would it really help being able to swivel the nose another 10 degrees towards your target if you aren't actually turning faster towards him and are creating so much drag your speed washes away?

Canard = that tail plane you've got at the front, which controls pitch Angle of attack = the angle at which the airflow meets the wings - the bigger the angle, the greater the lift (and drag). On your Navball, Angle of attack is the difference between the yellow prograde circle and the orange -w- symbol. For example, the prograde is showing 5 degrees positive, so your direction of travel one of a 5 degree climb. But the -w- is right on the 20 degree mark, this means your angle of attack would be 20-5 = 15 degrees The further your Centre of lift is behind the centre of mass, the more stable is your airplane. But, this also means the plane is more nose heavy, the more it wants to pitch down on its own. Therefore, the more force your front control surface needs to generate to hold the nose up at say, 25 degrees angle of attack. At some point this control surface is going to be maxed out and unable to pitch up any more.

Turn rate is determined how much lift your aircraft can generate relative to its weight, nothing else (unless the limiting factor is structural failure..). Lift is determined by three things - 1) speed 2) angle of attack 3) wing area The trouble with increasing speed is that it increases the G force required to achieve the same turn rate in degrees per second. That leaves you with 2) and 3). When you slide your wings backward a bit, to create a bigger gap between centre of lift and centre of mass, your ship becomes more stable, but you reach a point where that big tail fin you're using for a canard, becomes unable to pull the nose up to 30 degrees angle of attack, where lift reaches it's maximum. In many ways that's a good thing because at 31 degrees the wing stalls. That screenshot shows you're pushing things right to the ragged edge with centre of lift already, i'd never build a plane so close to being unstable - what happens when fuel burns off?

Re-entry is the process by which friction converts a spacecraft's kinetic and potential energy to heat energy. Firstly, if you're worried about burning up, you want to pitch up to an angle of attack that gives maximum lift. This keeps you out of the thicker air and causes the re-entry heat pulse to be spread over a longer period, which gives hot components more time to dissipate their heat, leading to lower peak temperatures. Angle of attack is the difference between the yellow prograde circle and the orange -w- symbol on your navball, with the navball in surface mode. Lift increases rapidly up to about 15 degrees angle of attack, after that it continues to go up slowly but you get an increase in drag. Peak lift is at 30 degrees AoA, after that the plane stalls and lift falls off very rapidly. Now, because we're human and holding a perfect pitch attitude isn't easy, I seldom aim for more than 20 degrees, because lift goes up so slowly beyond this and falls off a cliff if you overdo it. The drawback to "flying in like an airplane" is that all of the re-entry heat tends to get concentrated on the nose & leading edges of your vehicle. However, by deploying landing gear, opening cargo bays etc. to increase drag, these items can do some of the thermal -> kinetic energy conversion too. This has the practical effect of shortening the re-entry duration, which can help peak temperatures. Now, as a practical matter, even my Mark 1 cockpit spaceplanes have no issues re-entering on Kerbin, because my designs have lots of wing area and don't drop into the soup till going pretty slow. I like to make patchwork quilts of Big-S delta wings and keep all my fuel there - fuselages are for cargo, systems and kerbals only. I also prefer inline cockpits with a few things ahead of them in the vehicle stack, that way they're not the first thing to blow up if you do get it wrong and not the first to smack the ground if you prang the landing. For the belt-and-braces approach, put 1.25m heat shield with a little ablator right behind the nose cone of your aircraft. The nose cone will be first to pop, exposing the heat shield, which will then blanket the cockpit and stop it heating any further. In terms of placing the landing site accurately, i'll admit it's tricky. I normally aim for a 35km periapsis in the middle of the desert in the continent west of the space centre. If I'm undershooting, bear in mind that the best lift-drag ratio at hypersonic speeds is at 5 degrees angle of attack. You will actually glide furthest and travel furthest from your initial re-entry point at this angle. Above 5 deg, drag rises faster than lift so the distance downrange will be less the more you pitch up. So, if you're undershooting and not in danger of blowing up, try lowering the nose bit closer to the "best glide" angle. If overshooting, pull back to a near stalled condition and make more drag. I know it sounds kind of backwards, and for the first couple of seconds pitching down will make altitude drop faster as height is converted to speed, but pretty soon the trajectory line will show your landing point moving further away. As for pulling back on the stick to correct an overshoot, I actually think that's easier on the plane than making S turns. You're using lift to Up rather than sideways, so will stay higher and cooler longer, and you might welcome the buffer if you start having thermal issues. So, assuming your craft is like mine and doesn't come particularly close to melting on a normal re-entry, i'll start o