AeroGav

[quote name='Starhawk']Venusgate is right. Editor extensions is the one you want. Happy landings![/QUOTE] I have it, but still can't figure out how to make this do what i need :-( The shuttle wing has various strakes and control surfaces hanging off it, and it is already attached to the fuselage at 0 incidence. I want to rotate this wing by precisely 2 degrees in the pitch axis, but if i press 3 to select part rotation mode i can't see what angle i'm getting in fine mode and have a hard time getting repeatable results. Editor extensions lets me change the snap angle to 1 degree increments which affects the dihedral angle when attaching the wing assembly to the fuselage. Actually it makes it hard to get 0 dihedral. But it doesn't offer me any way to increase the angle of incidence of this wing??

Like I say I am not familiar with the stock aircraft but 100 m/s is crazy fast. I suspect you're flying the whole approach at high speed, which gives you less time to line up, makes it easier to overshoot, makes for higher rate of descent (harder touchdowns) at the same descent angle, and the excess energy/lift means the plane is going to want to float forever when you flare, or be very prone to bouncing. The best approach speed is going to depend on 1) air density - you're on kerbin near sea level so forget about that 2) design of plane - the ravenspear looks to have decent wing area so i would have thought it could fly slower 3) amount of fuel/cargo onboard - typically 70% of your mass is fuel and normally you'll be landing almost empty. For a training flight, don't take off with full tanks for a realistic experience? For any aircraft however, you can get a good idea of whether you're flying too fast or too slow for it by looking at your ANGLE OF ATTACK. What is AOA? It is the difference between your Yellow Prograde circle on the Navball -O- and the orange nose angle one --W-- In slower flight it takes more AOA to get sufficient lift to just fly level. Best lift-drag ratio is about 2.5 degrees. Below 2.5 degrees you're going so fast that drag from the fuselage is dominant, above 2.5 degrees your high angle of attack creates most of your drag. Fly slower, with higher AOA , you descend and loose speed more quickly, and have less energy to flare, but the low speeds make lining up on the runway easy and short flare makes it easy to touch down near the start of the runway. At the upper end, 3 degrees AOA is near your best gliding speed, but will make for a rather fast approach and a long float. If you have a draggy plane or are landing off-airport i might come in like this, means when i get to ground level and can finally see my shadow / landing lights on ground, i still have plenty of energy left if i want to delay touchdown or if i find myself facing upward sloping ground. EDIT - [URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-13_00029_zpshkgkyztg.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-13_00029_zpshkgkyztg.jpg[/IMG][/URL] This is me landing on Duna, with 1.05 patch. Since the last patch the air is VERY thin, so landings are fast. You can see my AoA is on the high side - 8 or 9 degrees, so i can't slow down any more or i won't have the energy to flare, or will risk a tailstrike. Fortunately this plane had 3 vernier motors in the belly, which helped me flare a bit. Here is an early mark 3 design coming down in Kerbin's deserts. I bounced a few times over the hillocks, this is the last bounce and speed is getting way low. Made for a hard final touchdown but no damage. [URL=http://s1144.photobucket.com/user/narostel/media/walkingpace%20reentry_zpsmapxzdd0.png.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/walkingpace%20reentry_zpsmapxzdd0.png[/IMG][/URL]

Hi, I'm designing a spaceplane with mk1 fuselage, and a pair of space shuttle style delta wings. The plan is to apply 2 degrees of incidence to these lifting surfaces, so all i need to do is set prograde and know i'll be at 20:1 lift:drag ratio for most of the ascent. The problem is , how do i get 2 degrees exactly? Tried eyeballing things, but it never looks right and is enough to drive you crazy. Downloaded this mod called PartAngleDisplay but it doesn't let you specifiy a target angle, or step in fixed increments (alt s and alt w change the displayed part angle but have no visible affect on the aircraft in SPH, even after save/reload, must be broken?) , it merely shows the angle as it is currently - and even then i don't trust it, because adjusting the wings manually in fine mode, there appear to be 3 steps that change how the wings look and the calculated centre of lift, but have no effect on displayed part angle until suddenly it jumps from 270 to 273 point something. So, if there are no better mods, can i just edit the craft file by hand? this appears to be the relevant section [code] part = wingShuttleDelta_4294264190 partName = Part pos = 0.6238493,10,-3.075839 attPos = 0,-0.4282098,5.104656E-08 attPos0 = 0.6238493,-0.7726269,9.21043E-08 rot = 4.214685E-08,0.7071068,0.7071069,0 attRot = 0,0,0,1 attRot0 = 2.980232E-08,1,8.42937E-08,2.980232E-08 mir = 1,1,1 symMethod = Mirror [/code] After rotating by hand, i get [code] part = wingShuttleDelta_4294264190 partName = Part pos = 0.6238493,10,-3.075842 attPos = 0,-0.4282098,5.104656E-08 attPos0 = 0.6238493,-0.7726269,9.21043E-08 rot = -4.213579E-08,-0.7231179,-0.6907248,-9.653921E-10 attRot = 0.6907248,-4.11704E-08,-4.11704E-08,-0.7231179 attRot0 = 2.980232E-08,1,8.42937E-08,2.980232E-08 mir = 1,1,1 symMethod = Mirror [/code] Looks like attRot is not as simple as adding say 2,0,0 to add two degrees incidence in one axis. Really, this is so frustrating. With rockets, it seems it's just about staging and choosing the right engines and fuel tanks, stacking cylindrical modules under each other. With aircraft, a few degrees attachment angle on your aerodynamic surfaces make a big difference. If you can't control the exact angle your wings attach at, the SPH is not fit for purpose.

I normally toggle the brakes on from the button at top of screen rather than by holding B since it takes so long. I've not actually flown the stock ravenspear but what i usually do is right click on each gear leg in the SPH and tweak the "set brake torque" value to 100%. For some reason it defaults to something much lower. Again, I've not flown the ravenspear but 100 m/s sounds a lil scary. I normally add a lot of wing area to my designs and they land under 40 m/s empty. Finally, I'd forget about landing ON the runway. Lining up laterally and worrying about precise touchdown zone make things much harder, it's also raised up on a berm which will wreck your plane if you hit it, as will the landing lights at the ends. Real approach lights are designed to come off worse in an airplane impact for that very reason ! Just land beside the runway on the nice flat grassland by the KSC, then taxy up to it if you must have the 100% recovery payout.

[URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-15_00001_zpsvuzhgp6a.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-15_00001_zpsvuzhgp6a.jpg[/IMG][/URL] Have to say I'm in agreement with OP - the heating on Eve is now too strong. I circularised at 93-95 AP - Periapse then did a burn down to 88km. Round and round and round we went, nothing happenning. Then at 77KM all hell breaks loose. Ship blows up less than 10 seconds after the heat bars appear. My best attempt was by burning radial at 82km till , at 2800m/s, i no longer had the thrust:weight ratio in my 3 LV-N to resist Eve's gravity. I shut two and three off and kept the left going full bore to put me in a flat spin. That delayed blowup to 72km. Eventually I hit Alt F12 and ticked the "ignore overheat" box. The atmosphere thickens so dramatically between 80 and 70km. At 71km it is thick enough for me to stop my descent with only 10 degrees AoA (was doing 2950m/sec at the time). This plane has no problems with Kerbin , it can also re-enter and land on Duna. It has lots of wing area (stall speed under 30m/s on Kerbin) and normally is able to skim the top of the atmosphere and avoid the worst of the heating. But on Eve it's nowhere close to surviving. I can't see a few radiators in cargo bays making a difference, anyone planning to add more , needs to consider the small matter of acheiving orbit again ! And ablators aren't available for aircraft , unfortunately.

[quote name='wizzlebippi']Wave drag is due to shockwave formation, transonic or supersonic, anywhere on the aircraft. A bow shock or shock cone is just the shock wave produced by the nose of a supersonic aircraft. A bow shock is a source of drag, but is not the entire source of wave drag. The main picture in this article should help. [URL]http://phys.org/news/2015-08-schlieren-images-reveal-supersonic.html[/URL] Anywhere you see a dark line in the schlieren photo is a compression wave and the lighter lines are expansion waves.[/QUOTE] Thanks for the reply, good to talk to someone who knows about these things. So, are intersecting shock waves bad, and avoided, like i assumed? Let's say that aircraft is travelling faster and higher and the shock cone off the nose was coming back at a steeper angle, the wings were longer, further forward and less swept, and the wing tips were hitting the bow wave. Would that cause much extra drag, even if those wings were razor thin like on an F104? I've not downloaded FAR yet (giving myself a break from spaceplanes, with a rocket-centric career game), but i get the impression that FAR is all about area ruling your aircraft to minimise the wave drag , shock waves vs component placement doesn't come into it so long as area ruling is good. Of course the two do overlap, much of the time. I've also noticed that the Skylon appears to have canards that would get caught in the nose shock cone at high mach, so my theory goes out the water there.

I have no training in aerodynamics but have been a plane spotter for many years, so now may be a good time to polish up my understanding of the concepts. I am aware of four main types of airframe drag 1) parasite drag - same as your car gets. Pretty simple and i think i understand this correctly enough. Mainly an issue when going fast at low level. 2) lift induced drag - related to angle of attack. Again, pretty simple and think i have this one down. Mainly an issue when flying very slow or very high in level flight, or pulling hard g's in other conditions. 3) transonic drag/area rule. Not sure what the correct name is. My understanding is this is most important when travelling close to mach 1 - but fades either side of it. Correct, partially correct, wildly wrong? The F106 delta dart is an early example - first prototypes couldn't break through the sound barrier, till they "area ruled " the fuselage - ie. make it fatter ahead of the wing and then pinch in at the wing root. This "coke bottle" fuselage enabled the airplane to get supersonic. 4) Bow Shock. OK, TBH I thought the proper name for this was "wave drag", but looking at FAR, it appears that "wave drag" is more what i understood 3) to be. This is probably total quackery but this is what my understanding of it was - At supersonic speeds, a shockwave forms at the nose cone of the aircraft, so supersonic designs try to keep the rest of the aircraft within this "bow wave" to avoid creating additional "bow shocks" from bits sticking out beyond. To avoid this you can a) use shorter span wings, like F-104 starfighter, and a long long nose b) larger sweep angles eg. English Electric lightning c) use a long nose and short heavy tail, mount the wings as far back as possible. eg. most 4th gen fighters (su-27, F-15 etc) The problem with c) is that it gives the tailplane a very short movement arm, so a large downforce is needed to pitch up. A lot of drag is needed to create that downforce, and that downforce is also subtracted from the lift produced by the wings, which is why a lot of Gen 4.5 aircraft now have canards, since air combat seems to be moving back to higher altitudes again. Canards have their drawbacks ofc, namely wings less efficient since not operating in clean air, generating negative lift to push the nose down when flying level in high dynamic pressure regimes, but again not what these 4.5 aircraft are optimised for. So, is this "Bow Shock" a thing at all, or did i just make it up to explain why high speed aircraft seem to have swept wings, shorter spans or wings placed quite far back along the fuselage? If it is a thing, is it modelled by FAR, or any other mod?

Something i often do early in my career is use wings to slow down from re-entry to parachute speed. Judging from my "aircraft landing" shot, that may be possible here.... edit - if you bring enough aero surfaces to have a stall speed below 220m/s, then you can probably leave off the heatshield to offset the weight of wings etc. Duna's thin atmo and low gravity mean winged entry without heatshield is survivable in 1.05, if you come in shallow and stay pitched up to 20-30deg angle of attack.

I managed to put an airplane on Duna, with plenty wing area and 3 vernier engines to provide vertical lift. I quicksaved about the time of this screenshot and had about 20 attempts to put it down. 5 fatal attempts, 14 nonfatal wrecks and one landing where everything stays in one piece. Sorry not much help really, as it sounds like less bother to do what you're attempting ! [URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-13_00029_zpshkgkyztg.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-13_00029_zpshkgkyztg.jpg[/IMG][/URL] [URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-13_00038_zpsg7e3c3kx.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-13_00038_zpsg7e3c3kx.jpg[/IMG][/URL] [URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-13_00040_zps59em9lgi.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-13_00040_zps59em9lgi.jpg[/IMG][/URL]

Update - I finally completed the Duna mission with this aircraft. The engines provided enough thrust to reach 1200m/s and 12km before "flaming out" which is a sub-orbital trajectory , a minor additional kick in "closed cycle" mode puts you in a proper orbit, with plenty of fuel left for the home journey. [URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-13_00029_zpshkgkyztg.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-13_00029_zpshkgkyztg.jpg[/IMG][/URL] Landing speeds on Duna are pretty scary. Burning the three Vernier motors on the belly helps arrest the rate of descent without pitching up to the point of risking a tailstrike, or increasing airspeed even further. [URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-13_00038_zpsg7e3c3kx.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-13_00038_zpsg7e3c3kx.jpg[/IMG][/URL] Success ! After about 20 crash landings, I finally put down in one piece. Duna does not seem to have any flat terrain. I flew around quite a while looking for it. Time to get the science. [URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-13_00036_zpsgw2cpjuc.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-13_00036_zpsgw2cpjuc.jpg[/IMG][/URL] If he can't figure out how to get out of there, he's going home coach class. [URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-13_00040_zps59em9lgi.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-13_00040_zps59em9lgi.jpg[/IMG][/URL] Obligatory selfie #1 [COLOR="silver"][SIZE=1]- - - Updated - - -[/SIZE][/COLOR] For the Eve mission, I became aware that aerodynamics had changed in the newest patch. If SSTO was possible at all, it was also going to be very marginal, so i started stripping stuff off the airplane. 1. The Vernier motors went, as did one of the reaction wheels, and the small tail bumper undercarriage leg. I was hoping to reach minmus with extra fuel thanks to all the changes, so would be able to land vertically. If not, the refuelling tender could always fly up and meet it, though neither is nimble or suited for docking maneuvers. 2. Because of the single reaction wheel, i can get all the science stuff in one small cargo bay. 3. The crew cabin went. I'm flying the mining ship to Eve orbit with this aircraft, so it can refuel just before deorbit. The Kerbals can use the crew cabin on this vessel to chill out. 4. The nose intake and type 2-1 adapter went, replaced by a mark 2 cockpit which apparently creates less drag, since there is less need for intakes. The downside is, it's the first thing to explode in the case of re-entry heating, and the first part to hit the ground in any mishap, without the crumple zone we used to have. The lethality of my "whoops" moments has increased dramatically, but i'm save scumming anyway because i CBA to refly the whole mission, nor can my space program budget afford to keep replacing very expensive aircraft like this. 5. Extra mk2 liquid fuel tanks went in in place of the above.. 6. And the rapier gets replaced by another modded LV-N. It now has 3 LV-N motors as sole propulsion. Unfortunately, it appears atmospheric re-entry on Eve is very hard since 1.05. This aircraft re-entered Kerbin from Duna orbit and re-entered Kerbin from Minmus orbit OK, but Eve is another matter. Speeds are high, and the atmosphere thickens very suddenly between 80 and 75km. I kept blowing up at 75km. Eventually I cheated and turned off heating. Turns out that despite being heavy with fuel, by 70km this airplane can stop it's descent with only 10 deg alpha. [URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-15_00028_zpsb2npnibz.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-15_00028_zpsb2npnibz.jpg[/IMG][/URL] Posing with the new , sleeker Batwing. Couldn't afford the drag penalty of a set of ladders , so we did the next best thing.. [URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-15_00027_zpscsp9a9o4.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-15_00027_zpscsp9a9o4.jpg[/IMG][/URL] Departure from Eve... [URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-15_00035_zps27bywtxa.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-15_00035_zps27bywtxa.jpg[/IMG][/URL] Unfortunately, this is as far as I was able to get. It appears the sound barrier is at a lower speed on Eve, and my engines make max thrust at about 800m/s. Any faster and they lose power. They also produce twice their closed cycle rating lower in the atmosphere at around mach 1.6, but by 36km, even at their optimal 800m/s, they are down to 60kN thrust. Unfortunately this isn't enough for me to climb any higher with. Even if i did, thrust would fall off. At this point, I can switch to closed cycle, but the more attentive among you will know that that is the Vacuum thrust rating of the LV-N. So it won't actually help. Well eventually, my plane will get lighter from burning off liquid fuel, which will maybe get us up some more, but I think it's fair to say we're a long way from SSTO. What more can I do? Well, could switch to a mk1 fuselage throughout, get rid of the shock cones from the nacelles and add a couple degrees incidence to the wings. Also worthy of note, in that pic I'm at about 5 deg alpha. True, i'm pulling more than 1g so it looks like i'm trying to arrest a phugoid, but perhaps more wing area still would get down to the optimum 2.5deg AoA at this altitude.

[quote name='Snark']There's a simple solution to the not-quite-aligned landing gear problem, and it doesn't require mucking around with cubic octagonal struts. Hit 3 to get the rotator widget, then F to toggle between "local" and "absolute" modes. Make sure you're in "absolute." In that more, the snap angles of the part you're adjusting will ignore the shape and orientation of the part it's attached to, and will instead align with absolute world coordinates. So once you have toggled it into absolute mode, just rotate the gear one notch and back again and it will be perfectly aligned. Simple, easy, magical, incredibly useful, and (alas) extremely non-discoverable.[/QUOTE] [QUOTE] [COLOR=#3E3E3E]The joint flexibility between the left and right sides is different, even with symmetry on. It's the same bug that causes a slow roll on otherwise-balanced airplanes.[/COLOR] [COLOR=#3E3E3E]Try mounting your gear to the fuselage and give it a go. EDIT. Or install KJR and see if it helps. On second thought, install KJR before you even start.[/QUOTE] Thanks to both of you for pointing out issues that have been driving me mad since day 1. A lot of the reason people give up on aircraft have nothing to do with the inherent difficulty of aircraft, nor the stock aero model (which is pretty simple) but issues with the SPH/Assembly system, it's user interface, and the lack of tutorial to cover ABSOLUTELY vital stuff like this. [/COLOR]

My spaceplanes have a lot of wing area and tend not to suffer much with overheating, pitch up the nose a bit to stay high in the atmosphere and all is generally ok, even after the latest patch. But, the story changed when i tried to bring it to Eve [URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-15_00001_zpsvuzhgp6a.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-15_00001_zpsvuzhgp6a.jpg[/IMG][/URL] Despite pitching to max lift, 30 AoA, and having a stall speed of less than 30m/s on Kerbin, the cockpit (followed shortly by the rest of the aircraft) explodes no later than 75km. Guess i'll be trying that "radiators inside a cargo bay trick".

I always liked the design of the Soyuz, it's a rocket wearing flared trousers.

I don't like working with Pitch because it's highly dependent on the thrust:weight ratio of your aircraft. I prefer Angle of Attack, which is the difference between the orange -W- marker and the yellow prograde -o- . According to this thread, http://forum.kerbalspaceprogram.com/threads/138291-Wing-Lift-Wing-Lift-to-Drag-Ratio-Charts Lift : Drag ratio peaks at about 2 deg alpha at lower altitudes, 5 degrees when you're getting up near orbital velocity. So, that is what i try to maintain for most of the ascent. I do my subsonic climb at 2 degrees AoA, pitching the nose up and down to try keep AoA constant. Actual pitch angle will depend on thrust weight ratio, and airspeed will depend on wing loading ie. how much wing area you have versus the weight of your vessel. I tend towards larger wings and moderate thrust weight, the climb generally starts at 120 m/s and gets up towards double that at 10km, with same AoA, because the air is thinning. I will deviate from this optimal pitch angle theory however, when it comes to the sound barrier. Drag nearly doubles at mach 1, about 330m/s, before settling back to near-subsonic levels. It starts to rise above 240 m/s and starts to ease off again at 430. So, i'll often fly at up to 10 degrees AoA, to stay subsonic as high as possible. If my pitch control surfaces are maxing out though, this creates a lot of drag so i'll transition before reaching 10 alpha. When I've decided it's time to go supersonic, I drop the nose by either setting prograde on autopilot, or just release the stick and let it fall back to the 2 deg AoA that's hopefully been trimmed for. Depending on wing area, this happens at altitudes from 8km-16km. After that it all gets very hectic. You're probably using Whiplash or Rapier motors, so once you go supersonic thrust goes through the roof just as drag is falling away, and a lot of this theory becomes moot. I generally level out from my sound barrier dive 10-13km and start pitching up to a STEEP climb, as the engines go ballistic. I'm still relatively low, so whilst I believe the lowest drag coefficient north of mach 1 is around mach 2, i don't want to get too fast yet, hence the pitch up. This is especially important after 1.05, if you don't want the cockpit to explode. OTOH, you need to start levelling off in time to make your speedrun. I used to set autopilot to prograde at about 15km which would level me for an 19km speedrun. Going over 1000 below 20km is no longer safe however. It's tough to strike a balance between nosing over too hard, and blowing up, and allowing the ship to balloon to too great a height, and not having the thrust to hit top speed. Looking at the engine config files, it might be safer to just aim for the optimum power speed of the engines, rather than absolute max speed. Below 22km at any rate. The Whiplash max out at 1050-1100, after that , the faster you go, the less thrust you get , whilst for the rapiers it's about 1200. Above 22km i generally light up the nuke, if carried. I switch over to rocket mode when the air breathers flame out or when the aircraft is no longer gaining altitude/airspeed. Maintain 5 deg AoA during the rocket part of the climb until above 40km or i can see from the aerodynamic forces display that the wings are no longer making significant lift. Then i set autopilot to prograde again and switch to map mode, and start thinking about apoapse and periapse.

My first manned mission to Minmus looked like this. The carrier plane launches the second stage on a sub-orbital trajectory. I'd bee-lined to RAPIER engines but had nothing better than a Gemini capsule at this point, so brought three of them so i could rescue a Kerbal, as well as have a pilot and scientist onboard. The thing is, taking off and landing again vertically uses a LOT of fuel, even on Minmus. So my next mission, I just brought the whole airplane. Figured that the fuel saved by 1) not having to kill all horizontal velocity before touchdown, and also therefore needing less vertical lift on approach due to residual orbital velocity 2) being able to taxy over the surface rather than lift off and touch down would offset the fuel used to drag wings, landing gear and engines up to Minmus. So it proved ! When taxying, there is almost no friction, at least without elevation change. You can cross the great flats loosing only 1 or 2 m/s in velocity. I drove from the flats to the poles, crossing 5 biomes. After freewheeling across the flats, we headed north to the highlands. This required gaining over 5000m in elevation so I used a fair bit of fuel (300LF?) doing so. After that I was coasting downhill to the north pole, riding the brakes. I was very worried about busting off a control surface, so kept my surface velocity to about 10 m/s. That certainly increased my fuel use when climbing to the highlands, due to increased gravity losses. As you can see from the picture we also brought a tourist. The science payout from this mission was enormous, more than i'd have got for slinging unmanned probes at Jool all week. Maybe if your vehicle is not an airplane, you can make it more robust and stable, and taxy at higher speeds, using less fuel. I would stick to landing gear legs rather than rover wheels, they're much tougher. The only advantage of rover wheels is that they're self driving.

Don't think real thrust reversers work like this btw. 1. Airliners have rather poor thrust weight ratio 2. The reverser is only certified for use at less than max power 3. Only part of the exhaust stream is diverted 4. The diverted exhaust goes in a mostly outward direction with only a small forwards component. The amount of retrograde thrust is barely able to reverse the jet out of it's parking bay, so why does it give such powerful retardation? The answer is that this stream of exhaust coming out perpendicular to the direction of motion disrupts the normally smooth airflow over the airframe and creates huge turbulence. The aircraft experiences drag as if it were shaped like a barn door, and it also destroys residual lift making wheel brakes more effective. Below 80 knots, this "virtual airbrake" effect dies down and the risk of re-ingesting exhaust gas is increasing , so they are usually stowed at this point.

not sure if i mentioned this before, but I'm trying to model a nuclear SABRE without the heat exchanger incoming air chiller bit. As i understand it, a SABRE is 1. ram air intake, velocity of vehicle compressing incoming air 2. heat exchanger, using the hydrogen fuel stream to chill the incoming air 3. turbine compressor of incoming air 4. hydrogen fuel will have been set boiling by the intake air (which was be hot from the compression it already endured going through the ram intake), so expands through a turbine, driving the compressor 5. compressed intake air fed into rocket chamber where it meets with the hydrogen and does the usual rocket thing. My "engine" was intended to be 1. Ram air intake 2. Compressor for intake air 3. First pass through reactor, heating it up to a max of 1600k , in order to 4. drive the turbine stage, which powers the compressor 5. Second reheat pass through the reactor, taking it up to max working temp of reactor if needed (higher than limits of turbine by some way) 6. expand through rocket nozzle. Since the air charge passes through turbomachinery with a maximum rpm at which it can remain intact, there is going to be less mass flow though the reactor at 20km than at sea level, therefore given the same max reactor temp, lower potential output. Ram air effect will compensate to an extent, but this means the air charge is already compressed with respect to its starting pressure before it even reaches the compressor stage. Even though the outside air temp at 60,000 feet is -40C, by the time you've boosted it back to 1 atm with ram effect, it will be quite a bit hotter by the time it hits the compressor stage than 1 atm air at sea level with no ram effect at ambient temperature. Will have to take a look at this AJE mod, sounds interesting. With stock game mechanics ALL airbreathing engines gain thrust with airspeed and loose it with altitude. That's not how real jets work - if you put a GE90 on a rocket sled at sea level and blast it to mach 5, it will not produce 5x it's static thrust, nor remain in one piece. But due to the way you're likely to gain airspeed and altitude at same time these curves will largely cancel each other out. Am also intrigued to try a mod with separate reactor making a resource - reactor heat and separate consumers - nuclear turbojet - consumes heat and intake atm, makes thrust up to mach 3 nuclear ramjet - as nuclear turbo jet, no thrust below mach 1 but produces thrust up to mach 5 turbo generator - consumes heat and intake atm , to make electricity nuclear thermal rocket - consumes heat and liquid fuel to make thrust You could tailor your setup towards a particular mission. ATM I'm struggling to think of curves that work corectly in Kerbin, Eve and Duna. Due to work commitments i'm going to have to leave this be till Friday. :-(

I'm struggling to work out the velocity and altitude curves still. Engines still feel overpowered below 15km and underpowered above. The original plan was they'd be little more than conventional NERV engines that help to lift part of their own weight on kerbin, without using any fuel while in atmosphere. In lower gravity environments they might shine. Now back to the curves, first principles (as far as i understand, please chime in) 1. Thrust should fall off linearly with air pressure except 2. It will get a boost that peaks at the bottom of the Stratosphere, from lowered air temps - 40%? 3. Thrust should rise linearly with speed Flying a normal ascent profile, getting faster as the air gets thinner, thrust should stay fairly constant until the limits are reached. The ram air compression from increasing speed compensates for the decreasing air pressure to an extent, but the problem is, the more you compress air the more it heats up, eventually thermal limits are being reached and then the only thing you can do is allow air pressures and volume into the combustion chamber to fall. Also this compression isn't free - ram air compression causes drag, having the turbomachinery do the work means more energy has to be extracted from the exhaust gas to drive it. Also at some point it exceeds max RPM and flies apart, but that's not something Kerbals worry about. Heck, there game's modelling of choke, rpm and critical temperatures is oversimplified to say the least... you're never going to create a realistically modelled engine. Meanwhile, my new "batwing" ship finally made it to Minmus, managed to land without busting any critical parts off on the third attempt, and got her tanks brimmed by my other space plane/IRSU vessel, "the goose". While docked, i transferred the three tourists to the goose (their ticket only goes this far, sorry), and will leave them to annoy Bill Kerman for the next three years while Arjorie, Jeb and Bob go gallivanting to the red planet. This will be my first manned mission in any save. Actually, looking at this link, http://wiki.kerbalspaceprogram.com/images/7/73/KerbinDeltaVMap.png I realised the setup i have now is total overkill. Nuke engines plus 2550 liquid fuel and we're already up at Minmus orbit. I could go literally anywhere on a fraction of the fuel load. But lets stick to the plan eh, and see how it flies in Duna, besides i have a contract to complete..

Update. hmm more test flights in order. The airbreathing nukes got it up to 14km, a brief burst from the rapier in airbreathing mode with stick backpressure released gets us supersonic at the expense of 2km. However , the nuke airbreathers won't go much above 650 m/s and 17km. I start up the rapier, but their thrust continues to fall off severely - like 14kn by 20km. So, onto closed cycle they go. We reach orbit, but barely enough delta V to intercept Mun, let alone Minmus. I'll tweak the numbers again, so they don't loose thrust quite so fast at altitude. velCurve { key = 0 1.05 0 0 key = 0.2 1.15 0 0 key = 0.72 1.4 2.433527 2.433527 key = 1.36 1.9 1.986082 1.986082 key = 2.15 2.2 1.452677 1.452677 key = 3 2.5 0.0005786046 0.0005786046 key = 4.5 1.5 -4.279616 -4.279616 key = 5.5 0 -0.02420209 0 } atmCurve { key = 0 0 0 0 key = 0.045 0.32 4.304647 4.304647 //30km on kerbin, like 70k ft on earth key = 0.16 1.4 0.5779132 0.5779132 //a bit over 10km on kerbin, 43,000 ft on earth key = 0.5 1.2 0.4809403 0.4809403 //about 18,000 ft on earth, about 15,000 ft on kerbin key = 1 1 1.013946 0 //sea level } But my spaceplane needs more than 1700 liquid fuel. The precooler intakes and cargo bays are major attachment nodes for the rest of the structure. Touch those, i may as well start over. But I reckon i can add a couple mark 1 liquid fuel fuselage sections ahead of the precoolers, and not have it look to awful. I had more oxidizer than was really necessary, so i may remove the small ft-100 rocket fuel tank from forward cargo bay (was locked, the idea being to guarantee enough for vernier retro burn on minmus). Put an orbital survey scanner in it's place, and just be vigilant to terminate the rocket burn with a little bit to spare....

Decided to run one flight test on the new airframe after all, since there is nothing worse than flying to another planet, re-entering then discovering your plane is uncontrollable empty. So, I emptied all the tanks, filled the cockpit with A listers and took it for a brief spin. It appears there's little agreement between the crew as to whether it's a sound design or not. It's surprisingly nimble and has a very low stall speed, perhaps below 30 m/s , but it's hard to say because this is the first creation of mine that really does STALL as opposed to running out of pitch authority and starting to sag. The nose stays level while airspeed and lift drop to almost nothing and AoA shoots to 70 deg quicker than you can blink. Need to slam the stick forward to recover. 20T/30T - there's not much difference in dry/wet mass, for a spacecraft. Payload is a science junior, mystery goo and collection of instruments. I'm including a crew cabin for RP reasons - maybe just maybe there's enough room for a space toilet, shower, bunk bed, microwave and xbox. Well, if the crew were romantically involved at any rate. It also has 3 Vernier engines thrusting straight down from the belly,a small tailwheel and two big ass reaction wheels, to make the horizontal landing on Minmus safer. We'll see...

Alright, I've think I'm finished putting the basics in. It should work, but i won't really know till i reach another planet. Time to build a 2 nuke / 1 rapier mk2 vessel for the maiden voyage. It can refuel on Minmus, i've an IRSU spaceplane there that's already filled its boots. Flight test program, you say? Not for Kerbals. Got a brand new, untested prototype engine with a brand new, untested airframe from R&D? Time to boldly go! On that previous flight, i think i accidentally stumbled across the most efficient airframe i've ever built. Was very definitely going to orbit on just 60kn thrust. The airbreathing version didn't break the sound barrier, because with nothing to burn the fuel off it was too heavy to get above 10km on full tanks, subsonic. I could push the nose over, but by the time i'm through 380m/s where drag coefficient is coming back down again, i'm down to 5km altitude and the atmo drag is huge anyway. I'm still not sure about the velocity and height curves but it's time to just fly the damn thing. Looking at the Atomic Age mod made me realise a big flaw in my plan - IntakeAir really means intake oxygen, and existing air intakes have a checkForOxygen - if the atmosphere they are passing through has no oxy, they don't take any air in however thick it might be. So, i've had to add another resource type to Resources.cfg (IntakeAtm), and modify the only two intakes i'm ever likely to use on a late-game ship, the pre-cooler and the shock cone, to gather IntakeAtm as well as IntakeAir. Needless to say, I set the IntakeAtm to NOT check for oxygen. Here is the "Alpha" of my modded LVN config PART { name = ImprovedNTR module = Part author = NovaSilisko mesh = model.mu scale = 1 rescaleFactor = 1 node_stack_top = 0.0, 1.40383, 0.0, 0.0, 1.0, 0.0 node_stack_bottom = 0.0, -1.731957, 0.0, 0.0, -1.0, 0.0 //fx_exhaustFlame_blue = 0.0, -1.6, 0.0, 0.0, 1.0, 0.0, running //fx_exhaustLight_blue = 0.0, -1.6, 0.0, 0.0, 0.0, 1.0, running //fx_smokeTrail_light = 0.0, -1.6, 0.0, 0.0, 1.0, 0.0, running //sound_vent_medium = engage //sound_rocket_hard = running //sound_vent_soft = disengage //sound_explosion_low = flameout TechRequired = nuclearPropulsion entryCost = 45000 cost = 10000 category = Engine subcategory = 0 title = LV-N "Nerv III" Atomic Rocket Motor manufacturer = Jebediah Kerman's Junkyard and Spacecraft Parts Co description = Cynics would argue that by the third installment of the LV-N series the Junkyard Parts Co were just cashing in on earlier successes. However, for some , the airbreathing mode represents true progress. attachRules = 1,0,1,0,0 mass = 3.5 //up half a ton for the turbo machines // heatConductivity = 0.06 // half default skinInternalConductionMult = 4.0 emissiveConstant = 0.85 dragModelType = default maximum_drag = 0.2 minimum_drag = 0.2 angularDrag = 2 crashTolerance = 12 maxTemp = 2500 bulkheadProfiles = size1 radiatorMax = 0.35 EFFECTS { power_open { AUDIO { channel = Ship clip = sound_jet_deep volume = 0.0 0.0 volume = 0.05 0.6 volume = 1.0 1.0 pitch = 0.0 0.7 pitch = 1.0 1.4 loop = true } PREFAB_PARTICLE { prefabName = fx_smokeTrail_light transformName = thrustTransform emission = 0.0 0.0 emission = 0.05 0.0 emission = 0.075 0.25 emission = 1.0 1.25 speed = 0.0 0.5 speed = 1.0 1.2 localOffset = 0, 0, 1 localRotation = 1, 0, 0, -90 } } running_closed { AUDIO { channel = Ship clip = sound_rocket_spurts volume = 0.0 0.0 volume = 1.0 1.0 pitch = 0.0 0.2 pitch = 1.0 1.0 loop = true } MODEL_MULTI_PARTICLE { modelName = Squad/FX/shockExhaust_blue_small transformName = thrustTransform emission = 0.0 0.0 emission = 0.05 0.0 emission = 0.075 0.25 emission = 1.0 1.25 speed = 0.0 0.5 speed = 1.0 1.2 } } } MODULE { name = MultiModeEngine primaryEngineID = AirBreathing secondaryEngineID = ClosedCycle } MODULE { name = ModuleEnginesFX engineID = AirBreathing powerEffectName = power_open //runningEffectName = running_open thrustVectorTransformName = thrustTransform exhaustDamage = True ignitionThreshold = 0.33 minThrust = 0 maxThrust = 60 heatProduction = 130 useEngineResponseTime = True engineAccelerationSpeed = 0.2 engineDecelerationSpeed = 0.35 useVelocityCurve = False //spoolEffectName = running_open engineSpoolIdle = 0.05 engineSpoolTime = 2.0 EngineType = Turbine PROPELLANT { name = IntakeAtm ignoreForIsp = False ratio = 6 } atmosphereCurve { key = 0 3200 0 0 } // Jet params atmChangeFlow = True useVelCurve = True useAtmCurve = True velCurve { key = 0 1 1.15 0 key = 0.2 1.35 0 0 key = 0.72 1.63 2.433527 2.433527 key = 1.36 1.9 1.986082 1.986082 key = 2.15 2.3 1.452677 1.452677 key = 3 2.3 0.0005786046 0.0005786046 key = 4.5 1.5 -4.279616 -4.279616 key = 5.5 0 -0.02420209 0 } atmCurve { key = 0 0 0 0 key = 0.045 0.2 4.304647 4.304647 key = 0.16 0.7 0.5779132 0.5779132 key = 0.5 1.1 0.4809403 0.4809403 key = 1 1 1.013946 0 } } MODULE { name = ModuleEnginesFX engineID = ClosedCycle runningEffectName = running_closed thrustVectorTransformName = thrustTransform exhaustDamage = True ignitionThreshold = 0.1 minThrust = 0 maxThrust = 60 // Max thrust of 60 is one third of what comparable engines do heatProduction = 250 fxOffset = 0, 0, 1.6 EngineType = Nuclear PROPELLANT { name = LiquidFuel ratio = 0.9 DrawGauge = True } atmosphereCurve { key = 0 777 // Vacuum ISP of 800 is really good key = 1 583 // But at sea level, it's super lame, i'm usig rhino numbers key = 2 0.001 } } MODULE { name = ModuleAnimateHeat ThermalAnim = overheat } MODULE { name = ModuleGenerator isAlwaysActive = true OUTPUT_RESOURCE { name = ElectricCharge rate = 5.0 } } RESOURCE { name = ElectricCharge amount = 0 maxAmount = 0 isTweakable = false hideFlow = true } MODULE { name = ModuleTestSubject environments = 8 useStaging = False useEvent = True } MODULE { name = ModuleSurfaceFX thrustProviderModuleIndex = 1 fxMax = 0.5 maxDistance = 20 falloff = 2 thrustTransformName = thrustTransform } MODULE { name = ModuleSurfaceFX thrustProviderModuleIndex = 2 fxMax = 0.6 maxDistance = 30 falloff = 1.6 thrustTransformName = thrustTransform } } Here is the modded ResourcesGeneric.cfg - RESOURCE_DEFINITION { name = LiquidFuel density = 0.005 unitCost = 0.8 hsp = 2010 flowMode = STACK_PRIORITY_SEARCH transfer = PUMP isTweakable = true } RESOURCE_DEFINITION { name = Oxidizer density = 0.005 unitCost = 0.18 hsp = 1551 flowMode = STACK_PRIORITY_SEARCH transfer = PUMP isTweakable = true } RESOURCE_DEFINITION { name = SolidFuel density = 0.0075 unitCost = 0.6 hsp = 920 flowMode = NO_FLOW transfer = NONE isTweakable = true } RESOURCE_DEFINITION { name = MonoPropellant density = 0.004 unitCost = 1.2 hsp = 3000 flowMode = STAGE_PRIORITY_FLOW transfer = PUMP isTweakable = true } RESOURCE_DEFINITION { name = XenonGas density = 0.0001 unitCost = 4 hsp = 120 flowMode = STAGE_PRIORITY_FLOW transfer = PUMP isTweakable = true } RESOURCE_DEFINITION { name = ElectricCharge density = 0 unitCost = 0 hsp = 0 flowMode = ALL_VESSEL transfer = PUMP isTweakable = true } RESOURCE_DEFINITION { name = IntakeAir density = 0.005 unitCost = 0 hsp = 10 flowMode = ALL_VESSEL transfer = PUMP isTweakable = false } RESOURCE_DEFINITION { name = EVA Propellant density = 0 unitCost = 0 hsp = 3000 flowMode = NO_FLOW transfer = PUMP isTweakable = false } RESOURCE_DEFINITION { name = Ore density = 0.010 unitCost = 0.02 flowMode = ALL_VESSEL transfer = PUMP hsp = 1000 isTweakable = true color = 1,0,1 } RESOURCE_DEFINITION { name = Ablator density = 0.001 hsp = 400 flowMode = NO_FLOW transfer = NONE isTweakable = True unitCost = 0.5 } RESOURCE_DEFINITION { name = IntakeAtm density = 0.005 unitCost = 0 hsp = 10 flowMode = ALL_VESSEL transfer = PUMP isTweakable = false } Here is the modded intakeShockCone.cfg PART { name = shockConeIntake module = Part author = Porkjet rescaleFactor = 1 node_stack_bottom = 0.0, -0.625, 0.0, 0.0, -1.0, 0.0 TechRequired = hypersonicFlight entryCost = 21000 cost = 3050 category = Aero subcategory = 0 title = Shock Cone Intake manufacturer = C7 Aerospace Division description = A shocking new intake from the C7 Aerospace Division that brought you much adored parts such as the Delta Wing and the Standard Nosecone! attachRules = 1,0,1,0,0 mass = 0.025 thermalMassModifier = 8 // heatConductivity = 0.06 // half default heatConvectiveConstant = 0.75 // air goes into jet, not bashes on intake. emissiveConstant = 0.95 dragModelType = default maximum_drag = 0.3 minimum_drag = 0.3 angularDrag = 1.2 crashTolerance = 7 maxTemp = 2400 fuelCrossFeed = True bulkheadProfiles = size1 MODEL { model = Squad/Parts/Aero/circularIntake/ConeIntake } DRAG_CUBE { cube = Default, 0.7486105,0.6887614,0.7221569, 0.7486105,0.6887677,0.7221569, 1.213026,0.3,1.183155, 1.213026,1,0.100694, 0.7486105,0.6903304,0.7221569, 0.7486105,0.6871722,0.7221569, 0,-0.08307549,0, 1.25,1.083849,1.25 } MODULE { name = ModuleResourceIntake resourceName = IntakeAir checkForOxygen = true area = 0.009 intakeSpeed = 12 intakeTransformName = Intake } RESOURCE { name = IntakeAir amount = 0.9 maxAmount = 0.9 } MODULE { name = ModuleResourceIntake resourceName = IntakeAtm checkForOxygen = false area = 0.009 intakeSpeed = 12 intakeTransformName = Intake } RESOURCE { name = IntakeAtm amount = 0.9 maxAmount = 0.9 } MODULE { name = ModuleAnimateHeat ThermalAnim = IntakeConeHeat } } and engineBodyRadial.cfg (the pre-cooler) PART { name = radialEngineBody module = Part author = C. Jenkins, Porkjet rescaleFactor = 1 node_stack_top = 0.0, 0.9375, 0.0, 0.0, 1.0, 0.0 node_stack_bottom = 0.0, -0.9375, 0.0, 0.0, -1.0, 0.0 node_attach = 0.0, 0.0, 0.625, 0.0, 0.0, -1.0, 1 TechRequired = hypersonicFlight entryCost = 6200 cost = 1650 category = Aero subcategory = 0 title = Engine Pre-cooler manufacturer = C7 Aerospace Division description = Improves jet performance by pre-compressing and rapidly cooling the intake air. attachRules = 1,1,1,1,0 mass = 0.15 dragModelType = default thermalMassModifier = 1 emissiveConstant = 0.95 maximum_drag = 0.2 minimum_drag = 0.3 angularDrag = 1 crashTolerance = 20 maxTemp = 2000 // = 2900 fuelCrossFeed = True bulkheadProfiles = size1, srf MODEL { model = Squad/Parts/Aero/engineNacelle/Nacelle2 } MODULE { name = ModuleResourceIntake resourceName = IntakeAir checkForOxygen = true area = 0.005 intakeSpeed = 10 intakeTransformName = Intake } MODULE { name = ModuleResourceIntake resourceName = IntakeAtm checkForOxygen = false area = 0.005 intakeSpeed = 10 intakeTransformName = Intake } RESOURCE { name = IntakeAtm amount = 0.5 maxAmount = 0.5 } RESOURCE { name = IntakeAir amount = 0.5 maxAmount = 0.5 } RESOURCE { name = LiquidFuel amount = 40 maxAmount = 40 } MODULE { name = ModuleAnimateHeat ThermalAnim = Nacelle2Heat } } Thanks for everyone's contributions, and particular the creators of the atomic age mod. Would never have figured this out on my own.

Yours. Your last 500 booster megarocket deformed the tectonic plate. Now get a crowbar and bend it back up, before someone notices.

The next stage is to give the engine an airbreathing mode. That's going to require some careful editing of the config files, but at the end of the day is just cut n paste. I'm agonising over what thrust curves to give it though. The "Whiplash" turboramjet makes 5.8 x normal thrust at optimum airspeed. That seems like too much. If the working fluid is limitless you can trade ISP for thrust. Use a lower exit temperature for the fluid but pump more of it through, the reactor can operate at a higher power level without melting down. One site i found said a nuclear thermal rocket could get up to 2.7x more thrust by using water as working fluid rather than LH2. Atmospheric air won't have the specific heat capacity of water though. http://www.niac.usra.edu/files/studies/final_report/510Maise.pdf This site talks about a nuclear ramjet for exploring Jupiter. It mentions that a nuclear thermal rocket will have hydrogen at 50-100 atmospheres as the coolant, and that a their jovian ramjet will operate at only a few atmospheres. This airbreathing NERV is assumed to have a turbo compressor, but even the latest civil turbofans only operate at a pressure ratio of 50, and i doubt our turbo assisted nuclear thermal ramjet gets that high even with maximum ram air effect. So, we're using a working fluid with lower specific heat capacity than hydrogen, at a lower pressure. Does this mean our reactor has less cooling in airbreathing mode and will have to throttle back? Well, there's one other thing you could do, change the gas path through the reactor. When closed cycle, the H2 stream goes all the way from one end of the reactor to the other, to pick up max possible temperature and get as much thrust per litre of stored H2 as possible. If unlimited intake air is available, you could feed air in at different points and not have it traverse as long, acheiving higher flow rate but lower temperature. Lastly, we're NOT talking about a nuclear turbojet, where the turbine adds a LOT of thrust at low altitudes , but becomes a liability higher up. That means a big ass turbine and whole new nozzle, really a completely separate engine though as Van Disaster mentions in the second post, they could both share the reactor as a heat source. What I have in mind - Air Intake (passive compression, rises with airspeed) -> Turbo compressor (with bypass ducts at higher speeds) -> Reactor first pass (heat to 1500k max) -> Power Turbine (drives compressor) -> Reactor second pass, reheat -> Rocket chamber and nozzle. Oh dear. I'm way over my head. It's getting late and I just want to fly something.

OK, I can put this off no longer. Strong , sugary coffee is the order of the day as I make my first ever mod of the KSP game files. Scary stuff. I started small. Added the half ton of extra mass. I've also added electrical output equivalent to two RTGs. The decay heat from such a reactor in shutdown state would do that at the very least - if not melt the whole spacecraft. But I digress. And now to the first matter. atmosphereCurve IOW, what is the difference between ISP Vacuum and Sea Level, when in closed cycle mode (airbreathing mode is the next, and far more ambitious mod). The stock LV-N has a ludicrous, and horrible thrust lapse. 800 Vac 185 Sea Level It drops to just 22% of it's vacuum rating. Then again, if we look at the Poodle, with a 350 Vaccum Rating, it also lapses to 25% ASL. Must be a seriously overexpanding bell nozzle. It cohabits the tech tree with the Skipper lower stage engine, with a lower vacuum rating of 320, but which manages to hang on to 87.5% of that ASL. The Rhino, with a Vac ISP of 340, does 255 ASL - 75% lapse. The Kerbal Aerospike motor manages the same Vac rating as the Rhino but does 290 ASL, a mere 85% lapse. Obviously great numbers but honestly this felt like cheating. Why would anyone ever pick the Rhino? Real world aerospikes don't do quite so well. The Space shuttle main engine does 452 Vac and 366 ASL (81% lapse). The Aerospike motor of the ill-fated Venture Star program, had 436 and 339 (77% lapse). This is actually worse than the SSME on both counts, though the SSME is not something you want to play top trumps against. It also has a nozzle design that differs from the conventional bell design so give good performance at a wide range of altitudes, since this engine is operational from sea level to vacuum too. All things considered, I decided to steal the numbers from the Rhino. By 10km, the stock LV-N is already not far off it's vacuum ISP, and when i get this running right you should be airbreathing that low anyway, so ISP won't hurt. I applied a "gimp factor" based on the fact it's no longer a purely vacuum oriented nozzle. I'm assuming the Rhino could have made at least 350 if it was optimized for deep space like the Poodle, applying a similar percentage loss to the LVN's 800 gives a modded vacuum rating of 777. Applying the Rhino's 75% thrust lapse to that 777 figure gives us a 583 sea level ISP. PART { name = ImprovedNTR module = Part author = NovaSilisko mesh = model.mu scale = 1 rescaleFactor = 1 node_stack_top = 0.0, 1.40383, 0.0, 0.0, 1.0, 0.0 node_stack_bottom = 0.0, -1.731957, 0.0, 0.0, -1.0, 0.0 fx_exhaustFlame_blue = 0.0, -1.6, 0.0, 0.0, 1.0, 0.0, running fx_exhaustLight_blue = 0.0, -1.6, 0.0, 0.0, 0.0, 1.0, running fx_smokeTrail_light = 0.0, -1.6, 0.0, 0.0, 1.0, 0.0, running sound_vent_medium = engage sound_rocket_hard = running sound_vent_soft = disengage sound_explosion_low = flameout TechRequired = nuclearPropulsion entryCost = 45000 cost = 10000 category = Engine subcategory = 0 title = LV-N "Nerv II" Atomic Rocket Motor manufacturer = Jebediah Kerman's Junkyard and Spacecraft Parts Co description = Despite the success of the original NERV, the Gavro Aerospace corporation demanded improvements from the design team. This first upgrade traded some vacuum thrust for much better performance down low, not to mention a built in RTG for some always-on power generation. attachRules = 1,0,1,0,0 mass = 3.5 //up half a ton for the turbo machines // heatConductivity = 0.06 // half default skinInternalConductionMult = 4.0 emissiveConstant = 0.85 // engine nozzles are good at radiating, NTRs even better dragModelType = default maximum_drag = 0.2 minimum_drag = 0.2 angularDrag = 2 crashTolerance = 12 maxTemp = 2500 // = 4000 bulkheadProfiles = size1 radiatorMax = 0.35 //Default = 0.25 but nuke engines are meant to run hot MODULE { name = ModuleEngines thrustVectorTransformName = thrustTransform exhaustDamage = True ignitionThreshold = 0.1 minThrust = 0 maxThrust = 60 // Max thrust of 60 is one third of what comparable engines do heatProduction = 250 fxOffset = 0, 0, 1.6 EngineType = Nuclear PROPELLANT { name = LiquidFuel ratio = 0.9 DrawGauge = True } atmosphereCurve { key = 0 777 // Vacuum ISP of 800 is really good key = 1 583 // But at sea level, it's super lame, i'm usig rhino numbers key = 2 0.001 } } MODULE MODULE { name = ModuleAnimateHeat ThermalAnim = overheat } MODULE { name = ModuleAlternator RESOURCE { name = ElectricCharge rate = 5.0 } } MODULE { name = ModuleGenerator isAlwaysActive = true OUTPUT_RESOURCE { name = ElectricCharge rate = 1.5 } } RESOURCE { name = ElectricCharge amount = 0 maxAmount = 0 isTweakable = false hideFlow = true } MODULE { name = ModuleTestSubject environments = 8 useStaging = False useEvent = True } MODULE { name = ModuleSurfaceFX thrustProviderModuleIndex = 0 fxMax = 0.7 maxDistance = 50 falloff = 2.5 thrustTransformName = thrustTransform } } I quickly knocked up a little flier to test this modded engine, make sure it didn't blow up or ring a dinner bell for the Kraken. Hey Stasa, come over here. We got a job for you. Test fly this new and completely untested airframe with a new and completely untested nuclear engine on the back. And stop looking so damn nervous... It did a pretty good "vodka burner" impersonation, trundling painfully down the KSC runway, flopping off the end, barely holding a few metres off the water, almost going into the back end of the drag curve and stalling out. But eventually, airspeed began to rise, and it began a very slow climb. As we neared 7km, climb rate starts to improve. ISP is getting better, fuel is burning off, and drag is lessening. This airframe has horrible roll stability. In between logging thrust numbers and fighting to keep the wings level, i failed to notice for a long time that i was up against the sound barrier and encountering high drag. I eventually grabbed the pitch trim wheel and got the nose up, flying subsonic to 16km. Then i push over and accelerate through the sound barrier in a shallow dive. Supersonic and climbing again - Definitely supersonic Woah....

Hi Jeb, I'm also going to agree with what the others have said, landing speed is too high. Most of my designs have a stalling speed below 40 m/s when returning empty. As for the first Mk 3 I ever built ... Crash landing at 25 m/s doesn't even frighten Bob Kerman, well not much anyway. You can see this one just stitches together four Big-S deltas to make one very large delta. Effective and low part count, but not pretty. Your shuttle is rather short and fat , compared to my aircraft, so it needs a shorter span config. How about the approach used on my Minmus mining ship? I've clipped some Big S wing stakes to the leading and trailing edge of the main delta, to make a larger surface. It results, surprisingly, in a rather nice looking ogive (?). The strakes are longer than the edges of the delta , so they are clipping into the fuselage a little. You could use some rectangular pieces to make the delta start further out from the cargo bays. Big S strakes and Deltas are the min-maxer's choice of wing part, because they have the same 10:1 lift:mass ratio of the best wing parts, heat tolerance and tankage for liquid fuel. However I don't see any airbreathers on your design, so maybe this fuel capacity goes unused? In which case, use any wing pieces you like, except one of the swept wings needs to be avoided as it's lift : mass ratio is poorer than the others. Of course, lack of wing area is not the only reason for your high landing speed. If you fly with F12 (aerodynamic forces display) on, you will see that your elevons are raising the nose by applying downforce to the trailing edge of the wing. Relatively close to the plane's centre of gravity, they have to use a lot more (down) force to get the nose up than a conventional tailplane further back. But the best thing would be a canard surface up front, which adds lift rather than subtracting it when trying to get the nose up. As a minimal change, I'd say 1. add canard 2. as this moves the centre of lift forwards, move the main wing back slightly if necessary 3. remove the elevons from the trailing edge and attach a strake instead, for a .... tapered trailing edge. Why strake over elevon? Because control surfaces like elevons only have 5:1 lift : mass ratio , and no fuel tankage. If you're worried about the effect of all this on your ship's performance, http://forum.kerbalspaceprogram.com/threads/138291-Wing-Lift-Wing-Lift-to-Drag-Ratio-Charts you can see that best lift:drag ratio occurs at only 2-5 degrees angle of attack, which needs a lot of wing at high alt. There are counterarguments, but i'd say a larger wing won't noticeably worsen performance, at least. My "goose" doesn't want to go fast below 10km. However it can climb to 16km subsonic, then transition to supersonic. In the very thin air above 20km, it flies very well. Finally, on the subject of crashworthiness, I'm not yet convinced by the Mk3 cockpit. Yes it has higher impact resistance than others, but its positioning means Jeb & Co are always the first to arrive at the scene of an accident. This type II/III mining hybrid has an inline cockpit with landing gear below, canards either side, a crew cabin, cargo bay with ore tank, type 2 to 1 adapter (rocket fuel), service bay with 2 batteries, and a shock cone in front as "crumple zone". Which is just as well as horizontal landings on Minmus are pretty terrifying.