rcp27

A major challenge for designing low cost staged launchers is the cost of staging itself. You might think that a Reliant and FL-T800 fuel tank makes an efficient lower stage for a small launcher, and in mass/fuel efficiency terms, it is. If you add in the cost of decoupling it, though, the balance goes in a funny direction. A Reliant and a dry FL-T800 tank combined weigh 1.75 T. A TR-18A stack decoupler, while only weighing 0.05 T, seems a convenient way to stage it off to allow a lighter, more efficient upper stage. That coupler, though, costs 400. If you look at the kind of cost-to-orbit that is achievable in the game, it's likely to be cheaper to not stage those off and pay the extra fuel to bring the whole thing to orbit. That's one of the reasons why the ultra-cheap launchers I described earlier in the thread were specifically built around the idea of keeping the decoupling to an absolute minimum. I did have a go to see if it was possible to make one fly where I ditched the decoupler entirely, put the ant on the top, pushing backwards, but I didn't achieve orbit, though it was quite funny pushing an empty Hammer backwards.

Fuel for the plane (not counting the orbiter's tank) is 270. While getting confused about some odd cost numbers, I have now noticed that it appears the fairing itself, not just the "base" has a cost associated with it. For example a Hammer costs 400, a fairing base 300 and a tiny decoupler 300, so you would expect the cost of the rocket in my earlier post to go down by 1000 if I remove those (those being the "lifer costs". In fact it goes down by 1038 because that's the cost of the fairing itself. So call the cost-of-launch (assuming I can figure out how to recover the plane) about 310 (its fairing is a bit longer). Right, now I have to go and clear out all of these "2Cheap" "SuperCheap" and "BargainBasement" satellites from my LKO before they go all Kessler on me.

Same old Ant. I have a suspicion that the Ant may have its physics modelled as if it did have a fairing even if one doesn't show. For the sake of completeness, I thought I'd see if I could do any better in the SPH. I knocked together this little spaceplane That thing in the middle is a diverterless intake that also holds liquid fuel for the whiplash, and there are a pair of Sparks each with 3 Oscar Bs on the sides. The payload, at the front, is the same orbiter as before, still with its ant and single oscar B. I couldn't get the plane to orbit, but I achieved a suborbital flight with an Ap a little over 85 km. I ditched the fairing and launched the payload near the edge of space on the way up, took control of the payload and flew it to orbit while the plane began its re-entry. I achieved orbit with he plane still in the 60's, went back to the plane and attempted to fly it back to base. Because it was suborbital, re-entry heating was no problem, but on the return flight I ran out of fuel a little to the east of the islands with the island runway, so had to ditch in the ocean (which I did successfully with no damage). I reckon with bit of optimising and practice I could get something for that kind of price that would make it back to the runway. For such a light plane with a whiplash on the back it accelerates like you wouldn't believe. I set the undercarriage so that it sits with a nose-up attitude on the runway, and it practically flies itself. Obviously it only pays off if you get the plane recovery money.

My understanding is the radial battery, like the thermometer, just adds its mass to the part it's attached to, so doesn't unbalance the craft. It's inside the fairing (just), so doesn't have any aerodynamic issues. And it contains enough charge to transmit the all important science even on the night side of Kerbin. I've had a bit of a play around, and I think the key issue is the step from 0.625 m parts to the 1.25 m Hammer. I just launched a satellite using the 1.25 to 0.625 m structural part and a 0.625 m nose cone instead of a fairing. While the radial battery is OK from a mass distribution point of view, it's no good aerodynamically, so I had to use an inline one instead. I achieved orbit, but with a wafer thin fuel margin (less than 1 unit left in a less than 80 km orbit) and it cost more than the last one.

By the time the fins burned off the craft was flying in a straight line anyway, and as they were attached to the discarded booster, they aren't really that important. Right, just built a HECS, 1 Oscar B, 1 Ant, 1 Z-100 Battery, 1 Communotron 16 and 2 OS-Stat solar panels craft and put it on a Hammer under a fairing with a TR-2V decoupler and achieved orbit. Mine only cost 3298. The experienced KSP players will be shouting at their computers "fix your staging!" around about now. So the question is why did this work when my earlier HECS + Hammer tests went so badly wrong? The answer, it appears, is aerodynamics. I did a few test flights All had the Hammer at 40% and the flight trajectory was straight up. Hammer + HECS: unstable. Hammer + HECS + 3 fins reached a little over 20 km. Hamm, HECS, 3 fins and a 0.625 m nose cone: a bit better, reached 26 km. Hammer + HECS + 3 fins + 1.25 m nose cone. Similar, under 30 km. Hammer, Hecs, 3 fins, 1.25 m fairing: holy cow! Not only does this thing go up much much faster than the others, with the engine not burning out till over 40 km, it leaves the atmosphere with an Ap of over 280 km. Also, the drag reduction at the front means the fins can be ditched and a stable flight maintained. So I conclude that we all need to forget the old days of "fairings are just for aesthetics".

The problem with this analysis is it doesn't consider actually getting out of the atmosphere. If you go with a single SRB as a launch stage, you have to accept it's sub-optimal burn profile (constant thrust until the fuel is gone) and the need to get out of the thermally and aerodynamically challenging part of the atmosphere. I haven't chosen the Thumper for either it's thrust or it's dV, but for the fact that it can get out of the lower atmosphere. I've just had a go at a basic test: I put a HECS probe core on a Hammer, nothing else. That was a total failure: it's aerodynamically unstable. I added 3 fins. After a reasonably involved test campaign with different thrust settings and attempted launch trajectories, I never managed more than 22 km. I'll grant that I didn't find the optimum, but I reckon 25 km is the maximum you'll get out of a Hammer. I don't approve of "explosive decoupling, but for The Sake of ScienceTM I had a go with a Hammer + Flea combo. Result: no decoupling As a result of extensive testing, all I can presume is that this "technique" has been removed from the game. Anyway, I moved on to Hammer, TR18-A decoupler and Flea as first and second stage, with a simple HECS in control. I did manage to achieve sub-orbital flight with an Ap of 99 km as my best shot, but the Flea + Hammer + decoupler costs 1000 while a single Thumper is 850, so I'm not sure where the benefit comes from. When I first created this concept, I didn't want to be ridiculously unrealistic, so I used a fairing, but experiments suggest it's important anyway (see below). Your points on optimising the orbiter are good ones. So I have run some tests as follows: Communotron 16, HECS, 3x OX Stat, 1x Oscar B, Ant, TR-2V decoupler, Thumper, 3x Basic fins. I found the result became unstable in the transonic regime. I'm not sure if this is due to aerodynamic forces or mass distribution. I added the 1.25 m fairing back in, and the result flew nicely. I found that if I flew a trajectory that resulted in a Thumper burn-out with an Ap of less than about 200 km (so more horizontal velocity), atmospheric heating becomes high enough to destroy parts (the fins all burn off, but the fairing protects the orbiter). The result is a successful orbit, but without the external battery the satellite has insufficient energy storage to actually transmit a temperature reading, so can't manage to bring any science home. Anyway, that launch cost me 3748 total, so that is a new personal best for "cost to orbit" for a minimum orbiter.

I'm home from work now and have re-created this launcher and flown a test flight. There is so much wrong with this particular launcher that it is borderline un-flyable. Anything approaching an efficient flight profile is just not happening. The first issue is that, while the Thumper can get this load out of the atmosphere, you don't have enough margin to do a very effective gravity turn. In the event, though, that's not much a problem. The real problem comes from the Ant. It gives a new definition to "feeble". The burn time required to get any kind of useful dV is insane. If you do make a nice gravity turn so you leave the atmosphere with an Ap of perhaps 85 km and a the rest of the energy in prograde orbital velocity, because the Ant is so feeble, you will go up to Ap, come down the other side and burn up on re-entry long before you are anywhere near orbital velocity. The only way I can make this thing fly at all is basically to go straight up. The objective is to get as high an Ap as possible from the Thumper to maximise the time I have between leaving the atmosphere and re-entering in the hope that the Ant can burn its six little legs off and achieve a stable orbit. The launch went something like this: Go straight up. The Thumper quits at about 40 km altitude, with an Ap of around 200 km. Once I hit 60 km, I ditched the fairing and Thumper, pointed between 25 and 30 degrees above the horizon and burned that Ant on 100%. All the way up. And back down again. I passed through Ap at about 220 km, and finally got the Pe above 70 km when I was at 140 km altitude coming down the other side. I flew this with the Thumper at 50% thrust, but didn't put too much effort into optimising it. The rundown of the whole craft is as follows: 1 communotron 16: cost 300, mass 0.005 1 Probodobodyne QBE: cost 360, mass 0.07 2x OX 4L 1x6 solar panels: cost 2x380, mass 2x 0.0175 (yes, I could get by with the OX stat for lest cost and weight, but I prefer bigger panels) 1x 2HOT thermometer: cost 900, mass 0.005 (redundant, there to demonstrate the satellite can complete contracts and do science) 1x Z200 0.925 m inline battery: cost 360, mass 0.01 (a pair of Z100 batteries would be cheaper for the same charge/weight) 1x small inline reaction wheel: cost 600, mass 0.05 3x Oscar B fuel tanks: cost 3x 70, mass 3x 0.225 1x Ant engine: cost 110, mass 0.02 1x TR-2V stack decoupler: cost 300 mass 0.015 1x AE-FF1 Airstream protective shell containing all of the above, cost 300, mass 0.075 1x Thumper SRB: cost 850, mass 7.56 3x Basic Fin: cost 3x 80, mass 3x 0.01 1x TT18-A launch stability enhancer: cost 200 (recovered), mass irrelevant. The orbiter itself has a dry mass of 0.27 and a cost of 3545 (dry), 3600 (wet). Total cost of launch (inclusive of payload): 5392 (5192 after launch clamp recovery). That's a total cost to orbit of 1647 plus a little over 2 Oscar B's worth of fuel (I had a little less than 1 tank left for establishing the target orbit, but that's plenty for completing most simple contracts). There are plenty of ways to make the craft more efficient if you think purely in terms of fuel burn, but they all add to the cost significantly more than they save. A kickback alone costs 2700, which is more than the total cost to orbit of this launch, so that's a non-starter. A Hammer lacks the dV to get the Ap out of the atmosphere, so would need to be combined with some other sustainer engine. That means a TR-18A stack decoupler. A Hammer plus a decoupler cost 800 combined before you add the cost of the sustainer engine. That's only 50 cheaper than a Thumper, but even a sepatron costs 75, and that's the cheapest engine in the game. In an earlier iteration of this launcher I used a Spark, which can achieve the same orbit with only 2 Oscar B's worth of fuel, and a much easier flight profile because it has something like 10 times the thrust. But a Spark costs 240 (so 130 more than an Ant) and the third Oscar B only costs 70 wet, so where's the saving?

I haven't done any detailed study, but for small payloads to LKO my feeling is that for minimizing cost with a disposable launch system, a system based on an SRB is the way to go. I've made serious money on LKO career contracts using a QBE core, a couple of solar panels, a communotron 16, 0.975 inline battery and reaction wheel as the payload, with an ant and 3 oscar Bs as an orbital engine on a 0.975 m decoupled, on top of a 1.25 m fairing, Thumper SRB with three basic fins and a launch clamp. For that king of payload, the cost to orbit isn't that far off the fuel burn alone for an SSTO capable of delivering the same payload.

One of the features I have always found a little frustrating is the lack of science from space. There are tons of biomes on planets, and a few biome specific experiments in low orbit, but mostly we just have space low and space high. I find there's a bit of a science drought between getting to Kerbin orbit and landing on Mun, after which science comes in huge quantities. Given that satellite contracts are offered differentiating things like equatorial, retrograde, polar, tundra and Molnya orbits, it seems to me there might be an interesting way of making actual space flight worthwhile beyond being simply a method of getting from one celestial body to another if being in different categories of orbit could grant science as separate biomes. It would give an incentive to actually do something other than launch to and equatorial orbit and just head straight for Mun.

I have my fair share of "Commsat" variants, as well as usually having a KSS. The other name I frequently use is "Moho" for my first ship to orbit as a nod to the Mercury program.

Presumably if you turn cross feed off and use fuel lines you can do asparagus the old fashioned way? I prefer to eat my words with fava beans and a nice chianti

Yeah, but that is such a massive improvement, I don't think it counts as a "little thing". I have years of muscle memory to unlearn now. When I launch my fingers just automatically hit T-Z-M. It'll take many launches before I can unlearn the M.

We've all read about the "big news" features in 1.2, things like communications net and balanced fuel flow. How about the little things? What new features have you found that you have noticed that make life a little easier? for me it's "When a Kerbal plants a flag, credit is given to all landed/splashed Kerbals in physics range. Prevents the need to have flag-planting parties with large crews."

A good suggestion. I've also found problems with planes being uncontrollable on the ground when the undercarriage is not strong enough for the weight of the plane.

I've encountered this problem when the wheels aren't quite straight. In the SPH, select the rotate tool, set rotation to absolute and make sure angle snap is on. Give them a wiggle and make sure they're set so the wheels are vertical and aligned axially with the plane. Most times that fixes the problem.

I have played KSP since 0.24. I have experienced the development of the game as the career mode has been fleshed out, as the old placeholder atmosphere was replaced by something more realistic, and then tweaked to balance realism with gameplay fun. I have seen the performance issues of the old game radically improved, and a whole bunch more improvements I've forgotten about. To my mind, with 1.2 (so far as I've seen in the preview), I think it's perfectly reasonable to draw a line under it and say it has achieved everything it needs to do, and is entirely adequate to stand as it is as a finished project. In this context, I think it's to be expected that the people whose vision and creativity went into achieving this decide that their job is done, and it's time to move on with their careers. There's no need to invoke conspiracy theories or assume ill will.

I think you've just described the weird ending bit of 2001: a Kerbal Odyssey

Thankfully Ed White's glove from Gemini 4 has come down, imagine finding out your million dollar's worth of satellite was destroyed because an astronaut threw a punch at it in 1965.

Sorry, I was a bit busy not crashing. I'll take some of my quality designs out for a spin and do some publicity shots next time

Well progress is slow but positive. I took my basic orbiter, pared it right to the bone, added as much fuel on the top stage as possible and managed a Mun flyby. With just the Wheasly and 1.25 m parts, putting something together that can get to orbit at all has proven pretty tricky. The only way to get a useful payload to orbit means using things like jet engines on decouplers as boosters to fly off the runway. With a capsule at the top that has to be capable of stable controlled flight after re-entry, getting a launcher that can fly straight both with and without jet engine boosters is a real challenge. I knew I needed to get a good chunk of science quickly, though. A bit of farming of biomes gave me the first bit step forward: the clampotron Jr. With this bad boy I can move on to building a craft capable of making LKO and refuelling it with robot tankers. A nice little craft with a Mk1 cockpit, a 2 man crew compartment (so that I can bring a scientist along to refresh the experiments), a Science Jr and a little cargo bay with batteries, thermometer, barometer and some goo is just the ticket. Made LKO with fumes in the tank, but help was at hand. Only problem is, although I have the docking port, I have not yet unlocked RCS. With a bit of care I managed to mate the tanker, fill the tanks and had enough left in the refuelled to clear up the space junk by sending it to a fiery grave. With the ship tanked up, and Jeb, Bill and Bob all on board, we made a nice transfer burn to Mun, with a Pe down around 35 km, and established a stable (but pretty highly elliptical) orbit. That got me the orbit Mun achievement as well as plenty of science both high and low. One of the problems with the 2-man crew pod, though, is it has no external door. Every time Bob had to go reset the experiments, I had to get Jeb out, transfer Bob to the cockpit, get him out to do the science work, and them get them all back on board without Jeb drifting away too far. This was where I met one the big challenges with this set of rules. No heat shield means carefully nursing the ship through multiple aerobraking passes and hoping to goodness the ship holds together. That Science Jr certainly has pretty poor thermal performance, and as we came down with flames everywhere and just about every component on the ship with angry red heat bars, I really didn't think I'd make it. Make it I did, though, and all that science gave the most valuable reward: Supersonic Flight. Now I have both the Panther engine and the first set of Mk2 components. A bit of flight testing and I put together a basic but practical SSTO that can get two crew up to LKO and land back on the runway all in one piece. All those stranded Kerbals waiting for rescue can breath easy, help is now on the way! So far I've been surprised at how much easier it is than I thought to progress in career with these rules. In the past I always regarded space planes as something you might consider later in the game, once you had at least the Whiplash engine unlocked. I always avoided unlocking the aircraft related nodes in the tech tree in favour of getting things like 2.5 m rocket parts. While I have had to leave some nodes to be unlocked later than I would normally like, it's not been too much of a challenge so far, and the solutions to the challenge of getting places under these constraints has resulted in some very "Kerbal" solutions. The next milestone will be actually landing on Mun.

I'm aiming here for the fun of a new design challenge, not for some sort of slavish following of arbitrary rules. The number one rule is that if a rule makes the game not-fun, then the rule gets changed. Hence, while I want return vehicles to be capable of a runway landing, if my re-entry flight is a bit off, I am happy just to land somewhere convenient and get on with the game. This is KSP we're dealing with here, and all craft come with small print. For this particular game the small print reads as follows: Craft are not guaranteed to be able to achieve the full capabilities of the design specification in all flight conditions. The inclusion of features to allow for the safe recovery of crew members in the event that the flight condition or configuration of the craft deviates from the planned mission profile is at the discretion of the designer. Any crew member employing such functionality where a board of inquiry finds that the flight condition at the time of deployment did not justify their use shall be subject to severe disciplinary measures including, but not limited to, assignment to experimental flight testing duty, employment as lubrication technician on off-Kerbin ore drilling installations or chief operations officer at the rocket launchpad (currently disused).

Normally I'm mostly a straight rockets person but have recently taken an interest in spaceplanes. Re-entry is a balance between spending enough time in flight to slow down and not crash but getting down quick enough not to overheat. With long thin rockets with heat shields, a shallow entry from LKO seems to work, but with planes this seems a recipe for firey death. If I have s space plane, say a Mk2 based SSTO, how should I attempt re-entry? What's a good height for PE after a de-orbit burn? Should I fly with a nose up attitude for maximum drag or a more straight on approach to get down to the high drag/high lift thicker atmosphere quicker to minimize time spent getting hot? Do radiator panels make a difference to survivability? Help greatly received

Sorry, wasn't entirely sure the right place to post it, figured a friendly mod type would be along soon enough to put me to rights

I know it's been done before, but in light of the space plane parts that came with, what was it, 1.1, I've decided to have a go at a non-vertical-launch space program. I'm setting myself some basic rules. The basic philosophy is that what takes off should be like a plane and what comes back should also be like a plane. I definitely don't want to just launch rockets from the runway, or come up with "workarounds" that let me launch from the runway what I would in another safe launch from the launchpad. My rules are, to an extent, a work-in-progress, and if anybody has any feedback or comments, I'd be glad to hear them. My first goal, though, is to make a fun challenge (the fun part is as important as the challenge here). So the first rule is: 1) if it leaves the ground, it starts on the runway, rolls on wheels and is powered by air breathing engines. Obviously I want to be able to collect the science from the launch pad, and I don't mind using the launchpad for things like "test landed at Kerbin" type easy-money contracts. I think this isn't enough, though. If My craft are going to be like planes rather than horizontal takeoff rockets, they have to do what planes do, and also come back. I don't think the tech tree is is well suited to SSTOs and SST-far-away if you're playing career mode, and I want to have fun, not grind in this save. I think therefore it's safe to allow for things like one-way probes, drop tanks, disposable stages (or, if funds allow, like the B52 that carried the X15 up to launch altitude/speed) and missions where I use dedicated non-returnable vehicles for things like transfers or landings (elsewhere). so, 2) If it lands, it has to be capable of a controlled rolling landing on the runway on wheels. If it doesn't come back, it doesn't matter. By basic criteria here are that I want to definitely exclude "falling under parachutes but happen to land on the runway" but definitely allow "I messed up my de-orbit burn and don't have the range to actually fly back to the KSC", hence the "to be capable" rather than "lands". Also, I think drogue chutes are cool. Parachutes are totally allowed if you deploy them after your main landing gear touches down. Hypothetically, if you can deploy them but maintain or regain controlled flight afterwards, that's OK, so in-flight chutes that you cut away before landing, or early-deployed landing braking type chutes are OK, provided you work within the basic concept that we are dealing with flying things not falling things. SSTO is not a requirement. I have no problem with drop tanks, one-way probes, disposable stages etc. I also want to allow the idea of an SSTO spaceplane that gets a refuel in orbit to allow it to fly on to somewhere interesting. The X15 space plane was dropped from a B52. I'm playing stock, so if I do something like that, the B52 analogue will be lost. That's totally OK by my rules. Equally, you may want a Mun lander or interplanetary ship that has no chance of coming home. These are all entirely fine by me. What I specifically want to exclude is cheating with a heat-sheild-and-parachute lander where the crew is rescued by a Kerbin atmospheric plane. Also, the simple solution of one-way mission is not really in keeping with the idea, so the last rule: 3) No Kerbal left behind. I've made a start, under 1.2 pre-release, and I'm having a blast. I want the career play through to be fun, so I've allowed myself two starter-flights of Mk1 pod, Mk16 parachute and Flea booster to unlock enough science to get to the "Aviation" tier that unlocks the basic "toothpick" undercarriage and Juno engine. I could have build some sort of rolling capsule based science-from-KSC type craft to get there, but that's too much of a grind for me. So far, I've got some nice planes that can do low altitude observation missions, and built a "SSTsubO" that gets me into space to achieve the "leave the atmosphere" contract. I've hit a bit of a barrier, though. I've unlocked the Weasley engines and built an orbit capable craft. It comprises 3x FL-T 200 fuel tanks, a LV-T45 Swivel first stage engine, a pair of Mk1 liquid fuel tanks radially each with a Weasley and basic circular intake, basic swept wing and a tail on the back, resting on toothpick tricycle undercarriage. On the front is a TR-18A stack decoupler, LV-909 Terrier, FL-T200 fuel tank, 1.25 m storage bay with science and a Mk1 cockpit. This will take off on the jets (needs extremely careful handling on the runway as the undercarriage is right at the limit), climb to about 8000 m under jets, light the rocket, the jets flame out at whatever altitude they get to, when the rocket burns out the capsule and terrier can get to orbit at 85 km with plenty of fuel to spare. I'm totally convinced this can form the basis of more substantial missions. The problem I'm now having is how to get back within the rules. I want my rules to allow for the game to still be fun to play. I have tested this ship by adding a pair of AV-T1 winglets as wings (placement vital to allow stable but controllable gliding) and a simple fin tail and a couple of batteries in the service bay. This allows the pod to re-enter from orbit, establish controlled gliding flight (using reaction wheels for control) and approach an arbitrary point on the surface nearby at a speed and descent rate that corresponds to a safe wheeled landing at the KSC runway. I see a couple of decisions I need to take now. Is it feasible to bring a craft down from orbit with the basic toothpick undercarriage, or will the blow up all the time? If they aren't viable, I'll work on the assumption that a safe ocean landing (i.e. one that doesn't involve destruction) in the water next to the KSC is as good as a landing on the runway, on the basis that they have a seaplane dock? I'm entirely convinced I could manage a safe splashdown on this craft. Would it make the challenge better if I required returning craft to not just manage a controlled glide approach but also a powered flight approach? I'm pretty sure I have the dV on this craft to do it, the question is will that requirement make for a better game?

When I dabbled in remote tech in the past I favored 4 satellites in 1000 km circular equatorial orbits because that would provide effective coverage within the range of a communotron 16 in RT. Going for a synchronous orbit brought hassles involving directional antennas in RT (not such a problem with the new stock implementation). Playing around with RT I personally found the easiest way to handle unmanned launches was to have something in low orbit and time my launch for when it passed overhead so that it could serve as a relay in case my gravity turn was too shallow to deploy a stronger than dipole antenna before the KSC dropped over the horizon. The current stock implementation is much more forgiving than RT, though (and rightly so, IMO).