The_Rocketeer

The KAX mod has a nice big undercarriage.

All winglets attached to the bottom of a rocket will stabilise it because they create a little extra drag behind the CoM. But I think what you're looking for is the table here: Control Surfaces

Sorry Jouni, but without wings that generate net lift, the vehicle is not a plane. A missile would probably be most accurate. I know what engineering is - my dad worked for Rolls Royce testing helicopter engines most of his life. But I disagree that KSP is at heart an engineering game. That implies that you start with an objective (specification) and design your craft to achieve it. I think that all newcomers, and many long-time players, tend or prefer to build a rocket that looks probable and then see what it can do. For these gamers, including myself 90% of the time, the engineering process is simply a case of refining what you consider probable, and not a case of mathematical engineering a vehicle that I know is capable on paper. The stock game encourages this style of play by deliberately limiting the amount of information you can harvest from it at any given stage of the construction or simulation process. It's only because mods have become available that a truly engineering approach can be viably made. Your second paragraph - realising that a plane performs as well with smaller wings - is an example of the engineering process I've just described. However, I think you have an unusual concept of what constitutes things like 'planes' and 'flight'. There is a massive difference between aerodynamic flight and the motion of a ballistic object under propulsion. In game terms, it's easiest to describe this in terms of whether the craft has a "direction of lift". And yes, wings are most beneficial at low altitude - precisely where rocket propulsion is least efficient. Also, the total drag force on wings is far lower than the lift force they generate, so this tends to increase the altitude at which lift gains are outweighed by drag losses, and basically means you need less dV overall. Anyway, as I've said before, I think we're straying from topic. Let's stick to the discussion of reasons to use SPs. If you want to start a new thread to debate what constitutes a SP or rocket, I'd be happy to weigh in.

I completely disagree with this post, not for the factual detail contained but because personally I think it saps all the fun from the game. I derive no pleasure from engineering craft that demonstrate the absolute limits of the game's mathematical formulae, I get a real kick out of chucking rockets and spaceplanes around and blowing them up when they fail or let me down somehow. I think this is true for the majority of players - the real challenge is to succeed in the face of uncertainty. I accept that there is a hardcore group that want to find the absolute limits for a particular set of rules, but I don't think that grabs the casual gamer and almost certainly isn't what the OP was asking for. I was fairly specific about the need for an atmosphere for most of these SP advantages to become relevant - that pretty much accounts for the Jool 5. Atmospheric SP descents are safer because they're slower and don't depend on thrust or parachutes, and cheaper because they require no extra parts or fuel. Short-roll landings aren't that hard for someone with my (virtual) piloting experience even on relatively steep slopes, and parachutes or VTOL remain an option if absolute precision is required - you'll still need less than a relaunch-capable rocket of equivalent dV. I am prepared to be proven wrong, but I am convinced that SSTO with a lift-generating craft is more efficient than SSTO with a thrust-only craft. This is based largely on experience of ion SPs with TWR of < 1.0, which simply wouldn't fly as rockets. Perhaps we should simply say that atmospheric missions will gain a number of advantages using a SP, but bodies without atmospheres are typically better off with a rocket. In any case, we are getting off topic by debating which is a superior mission platform. This is just a question of 'why bother'. We can add the assumption (correct or otherwise) that "a SP will be better for this mission" as such a reason.

Wow. Pecan, if you disagree maybe you could illustrate how exactly you think I'm wrong. 2. A SP of equivalent mass can reach orbit on less fuel than a rocket. Prove me wrong. 3. A SP can glide from orbit to land literally anywhere without using any fuel at all, without using parachutes. A rocket can't. 4. An SSTO rocket is MUCH LESS EFFICIENT than an SSTO SP. Lets stick to comparing specimen a (a rocket) with specimen b (a SP) shall we? 6. Really? Why? Show me a single complete rocket design that can compete with a single complete SP design (of comparable delta-V) for versatility of mission profile. This isn't a question about which is better, it's a question about why people would bother making SPs. I also couched my answer by saying it wasn't particularly detailed. If you like, I will specify that when I say SP I mean 'craft that launches horizontally, has wings and uses jet engines for primary thrust' and by rocket I mean 'craft that launches vertically and uses rocket engines for primary thrust'. As for whether a SP will be better, that COMPLETELY depends on the mission. There's no reason to suggest anyone's 'pretending' they're better - for a lot of things, they literally ARE better.

This is not a rocket in the conventional sense - a turbojet is not a rocket engine. This is confusing the fundamental question - most players will assume a SP is at least partly powered by jets and a rocket is mainly powered by rockets engines. You're also using air-hogging, which frankly I frown upon and never features in my SP designs - if it did I daresay I'd considerably improve my efficiency. Also, in your landing precision demo I have no idea what you were trying to land on/at. I can put a fully reusable SP on the last centreline stripe at the western end of the KSP runway with 0 fuel from reentry every time (or anywhere else, but I'm trying to specify somewhere you can find). I dare you to match it 5 times in 10.

No, a SP is not a rocket with wings. A SP is a aeroplane that can raise its apogee out of the atmosphere. This can be achieved with jet power alone, no rockets involved. Engine size also has nothing to do with it, even by your own standard. Anybody who assumes SP design will depend on rocket engines and staging has not appreciated the fundamental advantages of using an oxygen-rich atmosphere to reach space. If you flew a rocket-powered SP the way you fly a rocket, you'd find it's performance overall was lower because the wings would be dead-weight and subtract from max payload mass and TWR. My basic point was, for a given payload mass, an optimised SP will always get it space for less fuel than an optimised rocket. Precision landing is also easier and cheaper using a SP because you can use aerodynamics to glide towards your preferred landing site. If both designs are entitled to use parachutes, the SP can pick it's landing site at a lower speed, and corrections can be made by gliding and circling, potentially using no fuel. Rockets, by comparison, can only make corrections by thrusting. Without parachutes, it's even more fuel efficient, albeit marginally less precise on one axis (as in rolling distance), to land a SP. Think about it - Apollo aimed to land somewhere in the pacific, Soyuz lands in a desert region. Meanwhile the Space Shuttle lands on a runway. Rockets are easier to build, because they are basically a cockpit, a fuel tank and an engine. CoM and CoT are vertically aligned and CoL is basically irrelevant. SPs are harder because everything about them is more complicated. CoM, CoT and CoL all depend massively on where you designed them to be. Rockets and planes are different to fly, but the extent to which they're 'fun' depends completely on the player. I've had great fun with rockets, jets, VTOLs, and all manner of hybrids. Lastly, no. The two crafts are fundamentally different in engineering principle, performance capabilities and limitations, complexity of construction and piloting, and versatility. They are as different as dropping a stone and throwing a paper dart.

I deliberately used an example that highlighted the problem in terms that players can understand. The issue is that the stated value is ambiguously labelled, making its mathematical basis and therefore function, unclear. By extension, my example was also ambiguously labelled, but demonstrated the two possible interpretations of that ambiguity - the basis of the debate.

I'd have thought a little throttle control would be 'easier'. Clustering engines too tightly can also be a problem - they seem to 'share' their heat.

This isn't the most detailed or in any way conclusive list, but from the top of my head: 1: Most importantly, variety. (Not everybody gets their kicks from building phallic monstrosities.) 2: SPs are more fuel efficient than rockets per payload mass. 3: SPs are safer and cheaper to land on bodies with atmospheres than rockets. 4: SPs are reusable - rockets tend to come apart on the way up/down as they drop stages. 5: SPs look cool 6: One SP design can efficiently meet a very wide variety of mission profiles, whereas rockets are usually one-trick ponies. But there's no right or wrong way to play KSP. If you're having fun with rockets and find SPs too difficult, boring or un-fun, don't worry about it - stick to what you love

When in warp, a lot of the buttons from the RMB menu disappear. At a glance, I'd say this is the reason - you were probably in warp at the time you noticed it.

The confusion stems from the game's use of the term 'drag', which is the same for each part whether it is the coefficient or 'max_drag'. For a single part the stated drag rating, or max_drag value, is, de facto, a drag coefficient: in my example Object A's mass-weighted drag coefficient is 1.0 (mass) * 0.1 (drag) / 1.0 (mass) = 0.1 (mass weighted drag coefficient), which is the same as the initial 'drag' value. Since other stated values for parts are cumulative (mass, lift rating, thrust, etc), it's reasonable for players (such as Slashy and myself) to assume that max_drag values are also cumulative. Turns out not to be so because mass modifies both sides of the overall drag * mass : mass ratio. So, don't feel criticised for being unclear - as consistent as you might have been, the way this information is presented in the game is such that if you say 'drag coefficient' many will read 'drag rating', because, per part, this is a technically correct interpretation. In my example I was trying to link back to the values presented in game, which are listed simply as 'drag'. When you read these numbers, you're tempted to believe you're reading an absolute value that aggregates with other values in a rocket for a total rocket value. The whole disagreement between you and Slashy is basically whether that's the case or not, and as you've ultimately shown, it's not.

D'oh! Blame the wiki parts table, which lists it as being 0.1 mass. Actually, it's completely correct. Max_drag values (those listed as 'drag' in the part tooltips) are actually coefficients of drag for that part. Therefore, what you call drag (the mass-weighted drag coefficient) and what Slashy calls drag (the sum of max_drag values) are not the same thing. If this difference of meaning had been pointed out earlier, it might have saved a lot of pointless debate. This is the very heart of the entire disagreement. Nonetheless, I congratulate you on your ability to make (and demonstrate) a point.

I guess the RL A10 gets around this problem by balancing the CoT between CoM and CoL. Funky stuff. Sorry there wasn't a more satisfying answer

There are no stock batteries that weigh 0.05t. Also, radial batteries are massless and consequently wouldn't have any effect in the experiment. I think I can break this debate down into a really simple and understandable question, which will have a factual answer in the formula (for a mathematician to find): Consider two objects, Object A with mass 1.0 and drag 0.1 and Object B with mass 1.0 and drag 0.2. If you drop them in an atmosphere, then even though the force of gravity on them is equal Object A will fall faster than Object B because it has less drag. Now stick Object A to Object B to create object C. Here's the nub: Does Object C have 2.0 mass and 0.3 drag (Slashy's argument: 0.1 + 0.2), or does Object C have 2.0 mass and 0.15 drag (OhioBob's argument: [0.1 + 0.2] / 2).

My strong instinct on this is that due to the design of the A-10, your engine nacelles are above the centreline. The effect is that your engine thrust is pushing the nose down, because then engines are higher up on the plane than the CoM - the same as if you put one engine on a wingtip the plane would try to turn in circles instead of going straight forward. If your engines are up high like this, that's your problem. To fix, you'll need to work out a way to shift your CoM up, or your CoT down, or angle the nacelles so that they point towards the CoM - note this last will make your plane fly on a permanent upward pitch.

Considering how slight the difference is for very simple rocket in your example, the increase in mass is going to far outweigh the reduction in drag on larger, more complicated rockets where the drag reduction is even tinier and the mass increase is still the same. The only application I can see for nosecones is as a fuel-saving measure for faster-than-terminal-velocity ascents. And you're still better off throttling back.

This is my point. There are no dV savings from this approach.

This really has been discussed to death. The reason why a gravity turn is better (and it is) is this: When you launch to escape in a straight line, you accelerate at "thrust - gravity" all the way to escape. Very simple. BUT... When you launch and prograde gravity turn to escape, you fly in 3 distinct phases: Phase one: acceleration at thrust - gravity. This lasts until your gravity turn gets going and your trajectory becomes 'past Kerbin' rather than 'away from Kerbin'. Phase two: acceleration at thrust + gravity. This starts when your trajectory becomes 'past Kerbin' rather than 'away from Kerbin' and lasts as long as it takes for your trajectory to go back to being 'away from' rather than 'past'. During this time, you do most of the accelerating you'll need. Remember gravity is pulling you in the direction of Kerbin's centre, but relative to your rocket this is now much nearer 'sideways' than 'backwards', so it isn't really reducing your forward acceleration anymore, but it IS increasing your sideways acceleration. In other words, your total acceleration is now a synergy, rather than a subtraction. Phase three: acceleration at thrust - gravity again. By now, you're going so fast that you probably don't have that much accelerating left to do. Because you're going faster it takes less time to get to escape altitude, so gravity has less time to work on your ship. I've tried to explain this quite figuratively, which works for me. If someone who's got some equations to show this can illustrate it that way I'd appreciate the back-up

Stock physics doesn't account for slipstreaming parts - basically, all your drag coefficients are added up at the total decides drag force. I haven't used fairings mods so I don't know if they count as massed parts or not. If they do, they'll add to overall drag. If not, they won't help drag in stock.

When you're closing in on the target, it's important to match your velocity to the target (which I think is what you mean by 'having time to align with it'). The easy way to do that is make sure your speed display is set to Target (if it says Orbit or Surface, click on it till it changes to Target). Then find the retrograde marker on the navball and align to that. Wait until you're within a few hundred meters of your station, then thrust towards the retrograde marker until your speed gets to 0.0 m/s. At that point, you're travelling at the same speed and in the same direction as your target. Then it's just a case of thrusting gently towards the target to close in for docking. If you're more than a few hundred meters away, you'll find your trajectory seems to drift off the target - this is because of differences in your orbit altitudes, so although you're travelling the same way at the same speed for a moment, gravity is affecting you differently. The closer together you are, the less this is an issue, so just keep correcting and soon you'll be right alongside.

Gravity assists can be extremely useful, you can make very significant savings on delta-V using a string of well-constructed trajectory-modifying burns. It's also extremely satisfying to make a complicated plan and then execute it well. As a general rule the harder a thing is to do, the more efficient it will be. However... The more complicated the technique to understand, arrange and figure out, the higher the chance that something will go wrong, and therefore the more punishing the game becomes. To get the most from a gravity assist from Eve, for example, you need to time your departure from Kerbin so that you'll meet Eve at 180* around the sun from where you left. In practice, Kerbin and Eve are rarely aligned suitable to do this. In general, it's not hard to design rockets with an excess of delta-V for the intended mission and 'Kerbal' your way thru it rather than having a carefully calculated NASA-style plan that you stick to rigidly. Different players get their kicks from different styles of play, but "bodging it" is without a doubt the easier way to get results.

Staying as you are is fuel efficient. If you want to get there sooner, you should raise your apogee to let the station catch YOU up. This can bring you into an intercept at the next descending node, therefore in under one orbit (probably between 30 mins and 2 hours) vs an unknown number of orbits at 20 - 25mins a go, to catch up as you are. A good balance is to raise apogee above station orbit (and perigee TO station orbit), but aim for intercept on the 3rd orbit's descending node rather than the next pass. That way you know exactly how long it will take to phase and you'll only need about half as much delta-V to speed up and slow down again.

Now put that in your pipe and puff it....

Well FWIW I was being rude on purpose. I eagerly await further data.