davidparks21

There were a few others that looked out of place, enumerated in my post: http://forum.kerbalspaceprogram.com/threads/93779-SSTO-Spaceplane-Airplane-Design-Contest-II-Akademy-Awards?p=1545491&viewfull=1#post1545491 Edit: Never mind, it looks like you cleaned up that whole category and were referring to other categories! Thanks!

VOTING: Question/comment on voting for the best refueling tanker spaceplane, most of the entries in this category don't seem to meet the basic qualifications of a refueling tanker (e.g. it can take fuel to orbit!). A number of the entries can't even make orbit. Notably: - SP 40 B: this one was withdrawn as it won't fly in 0.25 - Orzel-4DSR H1HO-V3M: This is more of a general purpose spaceplane, its carrying capacity is pretty limited for refueling purposes - Matador: This isn't a refueling tanker, miscategorized - NAFA-7 Mamba Multi-role fighter: This is a sporty fighter, not a tanker - Spurce Moose: Won't even make orbit, not a refueling tanker - B-2 Spirit Bomber Mk2: Also doesn't orbit, thus not a refueling tanker. - Sleazy Weasel 7E - Great looking thing, but not really designed for fuel delivery (nor docking capability); Post doesn't seem to suggest it's a fuel delivery entry; lacking any discussion of delivery capacity/capability That leaves just 3 entries that meet the qualifications as I see it: - Erinyes (pretty good overall, if a bit crazy looking) - White lightening Mk2 (impressive, though maybe a bit overengineered, lacking good docking makes this one hard to vote for as a refueling tanker, though it pulls the largest load of any entry) - Mysteriously Nameless Tanker - My own (which I don't vote on) Thus my vote has to go to Erinyes as the defacto winner over White lightening Mk2 due to at least having docking capabilities. Irrespective of all else it's the only entry on the list, beside my own, that I see as capable of delivering a reasonable amount of fuel to an orbital dock, the fundamental requirement of the category. On a side note, I encourage all refueling enthusiasts to participate in the relatively new Balanced Orbital Refueling Challenge which forces entrants to balancing between cost, efficiency of ascent, orbital docking, payload delivery, and recovery procedures.

LOL, the kraken that hides between the seat and the keyboard strikes again! I've encountered him before too...

Oops, hadn't noticed the deadline. So a double thank you is in order! :)

Which links? The craft file? I just downloaded it in incognito mode without any problem.

Going for best refueling tanker spaceplane here: I present a sleek twin jet engine SSTO capable of delivering about a half an orange tank of fuel/oxidizer and some mono-propellant to a LKO (including docking) for a cost of only around 600\F per trip (not including cost of the fuel delivered, 2000\F total cost of fuel delivered + fuel used for delivery assuming landing back at KSC for recovery). Ejects on jet engines alone for an apoapis of 80k/periapsis 30k. Very stable and easy to fly loaded & unloaded, and easy/quick to dock when loaded. It was used to complete the balanced refueling challenge. So a lot more details can be found in that thread (piloting timing, payload breakdown, cost breakdown). Craft File Full album from the Balanced Orbital Refueling Challenge: Part Count: Average/Minimal (I'll update a count later, but it's generally quite average, no excess of parts as you can see) Mods: Only flight engineer; everything else is stock Flying instructions: Ejecting on twin jets is tricky. Take off and landing is easy, the vessel is VERY stable both weighted and unweighted. The trick to orbiting cheaply is to eject on the jets alone. However they're not balanced at higher altitudes. The vessel will handle inevitable burnouts and misaligned thrust gracefully, but you need to pilot the ejection properly. (1) Launch at a 45 degree angle (watch your tail end on take off, it's low) Up to about 20km. Engage SAS for the full trip. (2) As needed flatten out to keep one engine from going into burnout. Try to hold a vertical speed of 40-80m/s through ~30km while building horizontal speed. (3) At this point you'll loose one of your engines (burnout), the other engine is then the dominant one, cut back on the thrust limiter on the dominant engine until the second one re-engages. The plane will bobble slightly but SAS should handle it gracefully so don't sweat it (the vessel is capable of flying on a single engine, either one). (4) Now just keep dropping your thrust limiter on the dominant engine to keep the other engaged. Around 35k you might find you're dropping into negative vertical speed. That's ok, try not to let it drop too much (10-20m/s max), once you pick up speed you'll be able to climb again, ideally don't drop into negative, but don't sweat it if you do. (5) Around 38k you'll end up dropping your dominant engine down to 0 thrust limiter and climb the rest of the way on the other single jet. Keep climbing at around 5-20m/s or so. (6) You'll loose the second engine to burnout somewhere over 40k, at this point you should have an apoapis of over 100,000m. If you still have a negative periapsis you climbed too fast, try again and hold your vertical speed down until you pick up speed in the 30-40k region. Don't try a high incline ejection, the goal is to fly it straight until you're going fast enough to eject (at the point that your apoapis exceeds 100k you won't be able to hold the vertical speed down and will likely be pointing the nose slightly downward to keep from climbing too quickly!) (7) The moment you loose both jets immediately move to a 45 degree climbing glide. You'll see your vertical speed increase while you loose some apoapis height. Your apoapis shouldn't drop much more than about 80,000m, if you're a really slick pilot you can probably hold 100,000 apoapis. (8) At your apoapis engage the tiny jet engines and circularize for ~40d/v (you should be pulling up a periapsis of around 35,000m to 70,000m) Now you're free to do docking maneuvers. Note that all fuel tanks but the liquid and the last liquid/oxidizer tank are disabled, so if you need more than about 100d/v for maneuvers you'll need to unlock tanks. If you're planning on docking with something, take off when your target is exactly a 90 degrees before KSC to meet it efficiently. Landing is smooth, without any autopilot burn retrograde on the opposite side of kerbin to KSC, bring a periapsis down to about 35,000 above KSC and glide in. Keep the nose up to keep vertical speed down to around -80m/s, this will drop you in at about 20,000m just in front of KSC. Bring along 20 units of liquid fuel for some minor correcting burns as you glide in (burn around 25,000m to keep up altitude and speed if you're short). If you overshoot KSC you should be able to flip over and pull a hard nose dive to come into KSC from the east, the craft is well enough balanced to handle this maneuver (~10g's not sure how it'll play out in Near/Far). Action groups: (1) Disengage/Engage Jet engines (2) Engage/Disengage small liquid+oxidizer engines (meant only for small burns, circularization and docking)

Or if you're going to do so you should probably double down on SAS modules. I learned the hard way to test my lander on kerbin before sending it off to do its thing on Tylo. I always forget _something_!

Really? oh, I've *got* to try this out!!

Just saw this challenge today, after spending a ton of effort learning how to eject a medium-heavy refueling craft on dual jet engines for (this) challenge, I thought I could apply the same design approach to a smaller, high speed jet. And Indeed it seems to work. I present a dual jet, delta wing design utilizing 4 radial intakes (2 per jet). Top speed over land (measured by F3 menu): 2,270 m/s Top altitude attained under jet power: 36,711m No penalties, never passed about 40,000m (though had a high apoapis of nearly 150,000m at the peak), all stock other than flight engineer. Notable challenges for this design: - Imbalanced thrust: Stacking the jets allows the wings to provide stabilization, the two SAS modules go a long way to smoothing out the inevitable bumps and burnouts too. - As you climb above 30,000m one jet will always end up being "dominate", producing more thrust than the other, as the other goes into burnout you counter it by dropping the thrust limiter on the dominant jet. Thus you can obtain thrust from both jets even at high altitudes. I particularly enjoyed pulling the high speed descent maneuver at the end when I overshot KSC accidentally.

I was just thinking about making a challenge like this, did a search, and whamo, there it is! Awesome. This is on my to-do list! Great looking challenge, nice setup, I look forward to bringing back a nice little ornament for KSC.

At long last I've completed my own challenge, so without adieu, here is the first entry: A twin jet engine SSTO that ejects on jets alone and uses minimal oxidizer to dock with the station. It's quite competitive on cost, using just 600 units of jet fuel, a bit of oxidizer, and a touch of mono propellant, but takes a good long time to eject on jets. Nor did I do a masterful job of docking, so ding me for a little non Jeb-level piloting. Details: Delivered: 1384.01 units Liquid Fuel (arrived with 1455.08, undocked with 71.07 for return) 1708.56 units Oxidizer (arrived with 1755, undocked with 46.44 for return) 56.41 units Mono Propellant (arrived with 67.72, undocked with 11.31 for return) Timing: Docked @ 1:19:08 Undocked @ 5:31:09 Landed @ 5:53:56 Total time (excluding docked time): 1:41:55 (6115 seconds) Cost: 74,365 \F (cost at lift off) 72,229 \F (recovery value) = 2,136 \F total round trip spend Score: + 2028.95866 (liquid fuel) + 1445.44176 (oxidizer) + 97.75853 (mono-propellant) - 6115 (total time) - 2136 (total cost) + 10000 (challenge completion) ---------------------- = 5321 Notable challenges: - Ejecting on *two* jet engines required quite a learning curve, it's something I've been trying to work out for a while now. Ejecting a lighter plane on one jet engine is a lot more doable, but you won't deliver much of a payload on a single jet. Two engines requires that they be stacked vertically (so as to handle inevitable burnouts and misaligned thrust gracefully), and requires tweaking of the thrust limiter on the more dominant of the two jets as the other teeters on the edge of burnout between 30-40km.

After reading a few more accounts of trips on Xeon engines, I'm not quite sure about this detail... just want to make sure that everyone's aware that you *can* 4x time-warp (alt-warp) through long burns. If anyone's trying to do long ion burns at 1x time-warp, my hat's off to you.

Really interesting looking challenge. It's definitely bookmarked, though it does look like a solid challenge. I've been thinking about a visit to the sun too. I never knew it could be quite so interesting. I love how you've mixed the necessity of gravity assists into a mission that has a really unique and interesting end goal. Kudos on thinking this one up!

What?!! 0.25 is out?? Where have I been??? Oh, yeah, the moons of Jool... It was on 0.24.2.

I was definitely pushing for the low mass, I think I'm claiming one of the lowest masses without the use of a jet pack. That was the idea from the beginning at least, no atmospheric command seat nor jet pack use (though I did particularly like your solution how you came and picked up your orbiting kerbal with the remote pod). That ion lander was squirmish too, I tried everything to center the seat but couldn't get a design to work, as it only had a Probodobodyne OKTO2 for stability, the off-center weight of the kerbal made control problematic (though not impossible). The off center seat also threw the tylo lander way out of control (the little OKTO2 barely held the ion lander stable) until I added a full reaction wheel to the tylo lander.

Test it at KSC whatever you do, it took me like 10 tries over a month to get something that worked. I made a bunch of trips making it all the way to Tylo only to realize some fatal flaw in my design. When I finally got it right I started with the tylo lander design, launched it 500m and landed it in the hills behind KSC, that helped get the wrinkles out. Pol and Bop are easy, Vall is tougher, and laythe is an easier version of Kerbin. If you're using a command seat make sure you test it with a kerbal in the seat, their weight can throw off the balance of light weight landers (as I found out much to my chagrin). Remember also that for every second of burn time you have on the descent (and ascent) you need to add ~7.8m/s of dV to your requirement... That one bit me early on too as I tried using uber light engines that took 5+ minutes to burn down, but that long burn was adding like 2,000 dV to my landing requirement. Ouchie!

Tylo's where I started my design for a low mass contender too, you have to make some serious sacrifices to do it light, and will probably be cutting it pretty darn close. Striking a balance between the descent burn time (keep the burn time low, like a couple minutes, else you waste massive fuel against gravity), booster fuel efficiency, and weight is hard. Keep in mind that those LT-1 struts can take a pretty significant impact, I hit at over 20m/s on 4 of those on one attempt and actually bounced a good 5m high, dropped and still pegged the landing without breaking extended solar panels. I designed for Tylo first, then Vall, then Kerbin & Laythe, and Bop/Pol were easy. Make sure you're multi purposing every engine you send up. That 2.5 tons sounds like a good start, if you can keep things around about 10 tons, a single get engine plus about 300 units of liquid fuel will be able to shoot you into orbit on both kerbin & laythe for less than 100dV to circularize it. Now... how you get that stuff to Jool without blowing your weight limits is the hard question...

I'll do an album for Tylo and Vall again, honestly both were insanely hard and took numerous attempts, so I might have made a mistake and mixed in a shot from something other than the final successful attempt. On Tylo I had to land perfectly, I ended with about 1500 dv on the LV-909 (that took a number of tries, I landed it earlier with 1200 dv and couldn't get up), and barely skimmed the surface nearing the dark side at that. A 45 degree thrust on the LV-909 put me up to about 70,000 apoapis which just gave the Ions enough time to circularize (that lander is small so it picks up speed reasonably quickly on Ions). Vall was hard, but not quite as tough as tylo, trick was to land at 3000 meters, down at "sea level" the TWR is only ~1.01, landable, but uses the full 3100 dv available to the Ion lander. After a number of attempts I managed a hardish landing with a good 1500 dv to take off on, which was doable, but with like 80 dv to spare after rendevous. Tylo and Vall were where the patience really was tested. But 10 trips from Kerbin to Laythe were tedious (it took 10 designs to get something that worked). As for the parachute part clipping, I hear you, that was cutting it close, but in my defense there is actually an attachment point on the top of that parachute, I didn't use any mods or debug menu to pull it off, it was only what was possible in the stock builder (only mod I used in builder was the one that lets you change root nodes). On earlier designs I used two parachutes, but really couldn't afford the weight. I should have put it on the other side where I just decoupled staging portions. Additional details: Tylo Landing: - Landed with 1423 dV left in the thrusters, that was about 10 units of liquid fuel in the two side tanks and the center tank full. - I must admit that I'm missing many screen shots of the successful landing, what you're seeing for dV and tanks is the landing before the actual successful one, this one had 5 units of liquid fuel left in the two two side tanks, I did it again slightly more efficiently landing with 10 units, this was a critical difference. I thought I took screen shots of that one, but can't find them. Tylo Ascent: - The ascent was particularly hard on Tylo, probably the hardest of all maneuvers, the dV on the LV-909 was never enough, but it finally made due, pegging the thruster-ascent at 45 degrees gives the best tradeoff between lift (e.g. time for the Ion drive to do its work) and building horizontal velocity. The successful attempt had me just barely circularizing @ about 14,000m with about -140m/s drop rate and as I dropped into darkness. - Decoupling and switching to ion quickly was critical - Between the thrusters and Ion drive, pre-apoapis, (@45 degree angle on both) we made it to 90,000m, Giving somewhere on the order of 6 minutes of burn time to the Ion thrusters. Vall Landing: - DV after landing: 1533dv - Altitude at landing site: 3290 (1.076 TWR) (this was critical, I missed the mountain range a number of times, I could land it, but not with enough dV to take off again) - Notes: A key thing to note here is that the TWR changes significantly as you approach the surface, ranging from ~1.3 down to just over 1. Doing about 60m/s at 10,000 ft over terrain is approximately the optimal approach speed. My approach burned off the horizontal dv at about 30,000 m, turning nearly perpendicular to the surface at about -170 m/s vertical speed. Touch down at around 15-20 m/s. TWR at 10,000ft is more like 1.15, it's really finicky to find the perfect approach with the changing TWR. Vall Ascent: - The ascent was simple, straight up to about 15 m/s then crank it over as far and fast as you can without hitting the surface, I skimmed the mountain tops at just a few hundred meters (and on some attempts the mountain tops skimmed me). - Orbit made with 199 dV to spare for docking - Docking was a pain as all the maneuvers were near or on the dark side of the moon. - Docked with just over 80 dV to spare - You can see in the shots that the TWR at just 5000m (2000m over landing) is already a much more workable 1.1. Parachute part clipping: When I set it up I saw the connection point on top of the parachute, now that I look at it again I'm wondering if it's just letting me link to the lander can. In any case I could reorient the parachute to the other side which would actually improve the overall design a bit and wouldn't really affect the outcome of the mission (e.g. I could do it again with the minor modification, but that would be painful). Also it was nothing outside of what's doable with the stock system, which is what I generally consider fair game, so hopefully I can sway you on this point.

I would submit my Jool5 challenger, a half SSTO half moon lander that runs on Ion propulsion, Jets, and an LV-909 for the Tylo landing. The entire vessel weighs in at only 13,565kg at launch and stopped at all the moons of Jool before returning to Kerbin. As a side benefit, it has no RCS control either, docking the ion lander back with the command pod was more of a controlled crash than it was a docking procedure. You'll find the entire breakdown of the mission here: http://forum.kerbalspaceprogram.com/threads/57197-The-Ultimate-Jool-5-Challenge-land-Kerbals-on-all-moons-and-return-in-one-big-mission?p=1475782&viewfull=1 The short and sweet album: The full album:

​Before we begin, let us take a moment of silence in memory of all the brave kerbonauts who lost their lives in the pursuit of this challenge, their sacrifices did not go in vain. At a mass of 13,565kg, The Jool-10 plane and landing system (that's 10 attempts, not 10 moons!) made the journey to all 5 moons of Jool, and to the delight (and surprise) of Lambree Kerman, returned him and his science data safely to the surface of Kerbin. Highlights: - No EVA landings - All atmospheric maneuvers performed safely within the Mk1 Lander Can, no command seat in-atmosphere - 100% manual control (making for hellishly hard landings at Tylo and Vall) The breakdown: - Kerbin: Horizontal takeoff and ejection on jet engines, easy circularized on Ion Engines (200 units liquid fuel) - Kerbin/Jool Transfer: Ion engines with a lot of disposable tanks, direct entry to Laythe - Laythe: Horizontal landing and takeoff, same takeoff as Kerbin on jets (100 units liquid fuel) - Tylo: Jump up to Tylo from Laythe (for reasons of fuel weight), dump the jet, wings, and liquid tanks, land on a staged LV-909 engine, take off with ~1500 dv on the LV-909 and circularize (just barely) on Ion - Vall: We've now dumped everything but an Ion lander and lander can. Drop down to vall and squeak out a landing/redock on Ion engines using one 700 unit Xeon tank, redock with ~30 dv to spare. - Bop/Pol: Easily landed with the Ion lander and return to kerbin on Ion engins with plenty of dv to spare The short and sweet album: The full album:

At these speeds, who even needs wings, they just slow you down. Sure takeoff is interesting, straight down the runway to about 100m/s, then go wildly squiggly doing everything kerbanly possible to point the right end towards the sky. After that it's smooth sailing. 2325m/s was the final number before I ran out of gas.

I haven't used either of those, they look fantastic, and do look to be in keeping with the general purpose of the challenge. I'll allow them, but will specifically note they're use on the leader board.

Thanks for the correction on the Xeon Gas, those pesky zeros, basically worthless until you put them in front of something useful... I didn't actually realize that you recover more at KSC than any other landings (I don't use mechjeb myself and only occasionally manage a KSC landing). Given that point (thanks Laie) I think Cake's solution seems most in line with the goal and is simplest. I'll add a rule allowing you to deduct "docked" time. Part of the challenge is indeed rendezvous & docking, as large refueling tankers are beasts to rendezvous and dock, having a vessel that is as realistically manageable as it is efficient is a challenge goal. Yes, I meant 1/30th, I had played with a variety of combinations and just noted the wrong one.