capi3101

Alright y'all, thanks for your answers to my questions. I think I'll give it a go - if I don't like it, I should just be able to delete the directory and enjoy a few more weeks (hours, minutes, whatever) in the soup. Forum admins - I'd like to keep this thread open in perpetuity to whoever has questions regarding difference from stock to FAR. I don't know how long that will remain an issue given the upcoming change to the stock model, but I imagine folks in the future might need to ask their own questions and make their own judgments about which system to utilize. I myself might have some more questions on the matter a year from now - who knows...

I'll second the suggestion to install Intake Build Aid. Running your engines full throttle at 38k without loss of control up to that point appeal to you? Then get the thing. It's not cheatsy at all, it just does a job that needs doing with the push of a single button, with the end result of you will go to space today. Awesome regardless of aero model. I'm still not sure I hold to the notion that none of the general guidelines that apply in stock aero can't also be applied to FAR. I might have to install it just to either disillusion myself or come up with a few. Either way, a disintegrating plane is one sure-fire way of learning what doesn't work...

Well, I dunno about FAR; I do however know some magic formulas that work for stock aero, and that includes fuel. The general rule there for RAPIERs is 40 units of Liquid Fuel per tonne of mass at takeoff, and 25 units of Oxidizer per tonne of mass at takeoff. That number assumes the engine will switch over to rocket mode with the craft going 1750 m/s at whatever altitude you're at (and therein lies the difference between FAR and stock aero - I don't know how fast the RAPIERs will get you while you've still got air to work with). Now, my design process for figuring out fuel load typically goes like this: 1) Determine the mass of the payload. This is anything besides engines, fuel tanks, wings and intakes. The command module counts as payload, your cargo bay mass counts, anything in the cargo bay counts. 2) Multiply that mass by four - assume that's going to be the takeoff mass of the plane. That's going to give you a "25% payload fraction", which is what a lousy spaceplane design will usually give you. 3) Determine the number of engines needed to get that into orbit. For stock aero, the rule for RAPIERs is 13 tonnes per engine at takeoff. Your 54 tonne plane would require five RAPIERs in stock. My understanding is that the nerfing the Turbojet and RAPIER received in FAR was done to prevent those engines from being so powerful they'd rip your plane apart, and that the more realistic atmospheric pressure profile with height compensates for it (takeway there - you might consider reducing the number of engines on your plane. Whatever floats your boat there). 4) Now - and this is key - that maximum mass per engine is what you assume for determining fuel. If you've got 8 RAPIERs, you assume each one will lift its maximum tonnage of 13 tonnes, so you assume the takeoff mass of the plane will be 13*8 = 104 tonnes. So you need 104*40 = 4160 units of Liquid Fuel and 104*25 = 2600 units of Oxidizer. If you've got 5 RAPIERs, you assume each one will lift its maximum tonnage of 13 tonnes, so you assume the takeoff mass of the plane will be 13*5 = 65 tonnes. So you need 65*40 = 2600 units of Liquid Fuel and 65*25 = 1625 units of Oxidizer. There is no tank in the game that gives you a 1.6:1 LF/LOX ratio - those Mk2 Rocket Fuel Tanks certainly don't - so you usually have to wind up draining oxidizer from the tank. For the 65 tonne example, you could use a Mk3 Rocket Fuel Fuselage; it'd put you 350 units short on Liquid Fuel, but you can make up that difference easily enough with outboard fuel tanks and adapters (like those Mk2 Bicouplers you're already using. Like I said, I use stock aero - though I'm thinking of making the switch and I've been asking these kinds of questions about how things work in FAR. So take this advice with a big grain of salt. It might work for you, it might not; it's worth a try anyway.

Had a contract to put up a new orbital space station around Kerbin, which required a five-Kerbal capacity, a lab, power, and antenna and docking port. Since I had no use for a Kerbin-orbiting space station, I decided I'd build all that stuff into a spaceplane, launch it to orbit and bring it back down - the crew spaces would be filled with those Kerbals that didn't rate even a single star just yet. I haven't had a plane give me as much trouble as that one did in quite some time - must've done a dozen failed launch attempts, either due to poor wing placement (had too much lift towards the nose despite the overall CoL being where it needed to be originally), bad gear placement (I had one that absolutely refused to put itself in a position that would let the plane go straight down the runway - ultimately I realized I had too much weight on it and I needed to shore it up with moar struts), insufficient structural integrity (those cargo bays will do that crap to you sometimes) or insufficient pitch authority (moar elevators took care of that). But ultimately the mission was successful; recovered all but √2000 (cost of fuel) on a contract that paid about √65,000. So a good profit margin there. Still working towards unlocking the Level 3 R&D building; I took on a couple of base contracts that will payout √350,000 between the two of them. I do have a base design that will cover the two but I need to rethink the launcher; for one of them I would actually take a loss were I to use the current booster design. Might be time to build yet another mega-plane...and do it while I still can.......

The tags are [ spoiler=describe your spoiler here ] (content) [ /spoiler ], without the spaces in the tags. I continue to be impressed by your ring designs, BTW. I too swore a lot because I am considering the switch to FAR...... Kidding. Folks have actually been really helpful so far.

Thank you all for your replies so far. I probably should've mentioned that I do use Intake Build Aid and KER; Mechjeb has long been my scheduled reward for a successful launch from Eve, something I've yet to accomplish... Anyways, I meant that folks flying the souposphere have determined that there is a point past which the efficiency of the craft - and your chances of making it to space - drops off rapidly based on the number of engines you're working with. For Turbojets in the soup, that's about 15 tonnes per engine. That figure has been one of the keystones of my spaceplane design process for quite some time now. I suppose I left out that whole part of my usual design process for spaceplanes - I usually start a design with the mass of the payload, with payload being "anything that doesn't help the craft get into orbit". The obvious example is a space probe that you're launching to orbit. I usually start with the mass of that payload and assume a 25% payload fraction, which in the soup is generally what you get with a truly sucky-suck-suck design. So let's say I have a six tonne probe I want to launch. I multiply that by four - 24 tonnes. 15 tonnes max payload per Turbojet, so I know A) I need to build a two engine craft and I can assume the maximum mass - 30 tonnes in this case - when it comes to figuring out how much fuel I want on the craft and how many wing parts to put on. I also generally use three Ram intakes per engine (the guideline being 0.035 intake area per engine - left that one out). I generally design full "integrated engine units" by starting with an Engine Nacelle set along the craft's centerline. A Turbojet goes on the business end along with two-to-four 24-77s. I then take the Nacelle/engine assembly off, put it on the side of the craft, stick a tri-coupler on the other end of the Nacelle and then attach three Ram Intakes to the tricoupler. I'm assuming that the big fluting edge of the tricoupler is a huge no-no in FAR... Is there a similar general design process for FAR? Another big concern I have - right now in the soup I can load up an over-sized payload and get it into orbit. Take my Vampire Bat 7 design: Now - that flying pile of junk ain't making it to orbit in FAR; that's obvious. But let's say I wanted to do the same thing in FAR - a lander of the same design to orbit via spaceplane. I already know the lander is too big for any of the existing stock cargo bays; I tried fitting it into a Mk3 bay early in the design for no dice. How would I go about lifting that lander to orbit with FAR if I wanted to use a plane to do it? Is that even possible?

Obligatory link to guidelines for spaceplane rookies. Keptin's guide is a must. Now, for landing on the runway - landing on the runway pure stock is a tricky business. I myself recommend putting a flag (better yet, sending out a rover which you then reclassify as a base once it's in place) on either end of the runway as even with the centerline as you can manage, as close to the ends of the runway as possible without being on the "raised" runway section itself (if your flags are too close, the game will tell you about it when you try to launch a new aircraft and will clean it off the runway - making it disappear in the process). This is your "meatball"; you can use the distance to the flag to determine what your altimeter reading should be, and you can use both flags to check your alignment. For a roughly 5.7 degree glideslope, your altimeter should be (in meters) 100 times the distance to the meatball (in kilometers), plus 100 meters. For example, if you're 12.5 kilometers from the meatball, you want to be near ((12.5*100)+100) = 1350 meters. Much above that and you're too high, much below that and you're too low. You can extend this system out further on the landward side - markers at 1, 5, 10, 15 and 25 kilometers from the end of KSC 09 will help you with your alignment further out from KSC and give you more time to approach. The final landing needs to be gentle - you want your descent at touchdown to be no greater than about 5 m/s, or you'll crush your undercarriage. Preferably, you want SAS off on touchdown, but whether or not you can do that will be a matter of how stable the plane's design is. If you don't want to build a stock ILS, there's always the NavUtilities mod, an integrated ILS which is designed to assist with landing on any runway on Kerbin (including the KSC helipads at the VAB and Admin building). I myself use a combination of the two systems - the flag approach also gives you a marker you can use for your de-orbit to KSC. If you're at 100x100, put your periapsis at 44k right above KSC and you should cruise right on in (or at least be close enough for jazz to fly in the rest of the way). If you're higher, go lower, and vice versa.

Greetings, all. For the better part of a year now, I've been flying spaceplanes. It's taken me a while to learn the necessary tricks and to gather the tools I needed to be able to fly an aircraft into space consistently, but I've gotten to the point where I can do it consistently and have designs with specific purposes - such as lifting a full orange tank to orbit, delivering a Mun lander to orbit and bringing it back down to the runway, and delivering a space station crew to their post - around Mun. Now, from the beginning I've been flying with the game's stock aerodynamic model, which everyone (including the developers) thinks is pretty heavily flawed and which is scheduled to be heavily overhauled with the coming KSP version 1.0. Given that the replacement system will handle closer to the way FAR handles things, I've been considering making the switch from stock to FAR for the past couple of weeks. To that end, I built a challenge where I asked folks to lift the same Mun lander I did to LKO and bring it back down again using FAR (or NEAR), with the idea of learning a thing or two from the entrants. No one has entered, so at this point I thought I'd take a slightly more direct approach. Basically, I'm looking for information on how to design a craft and fly it to orbit using FAR - that goes for both spaceplane and rockets. What I'm really looking for is an answer to this question - is it worth making the switch? For my specific questions: -SPACEPLANE DESIGN- When I design a spaceplane, I first and foremost use the principles listed in Keptin's Basic Aircraft Design Explained - Simply with Pictures guide. I'm assuming those principles will be all the more important with the FAR aerodynamic model. I also have been adhering to DocMoriarty's KSP Space Plane Construction and Operation Guide for general figures on how to build craft (especially Chapter 2.4, "Numbers You Should Know Before Construction"). Those figures go like this: -A maximum takeoff mass of 10 tonnes for Basic Jet Engines (and these for aircraft and VTOLs only), 13 tonnes for RAPIERs and 15 tonnes for Turbojets. -Approximately 2.3 tonnes of mass per delta wing; I myself use the easier-to-remember 1:1 ratio of mass-to-summed lift coefficient. -1.5kN of SAS per tonne of takeoff mass. -39 units of Liquid Fuel per tonne of maximum take-off mass (I use 40), and 23-24 tonnes for Oxidizer per tonne of take-off mass (I use 25). He has other guidelines for number of rudders, number of ailerons and number of elevators/canards, which I do follow but don't really feel like discussing here. Do these same guidlines still apply in FAR? The big one for me (and the one that may kill any notion of a switchover) is that I've heard Turbojets are seriously nerfed in FAR itself. I have no intention of installing an aircraft parts mod (such as B9) at this time - I have a slow box and a fair number of mods as it is - and the Turbojet is what I generally use to get to space these days. How badly has it been nerfed? What is its maximum takeoff mass in FAR? Has the RAPIER been similarly nerfed? -SPACEPLANE FLIGHT- Okay, my typical launch profile for a plane in the soup goes like this: * Above 45 degrees through the first ten kilometers of atmosphere * 40 degrees from 10-15k * 30 degrees from 15-20k * 20 degrees from 20-30k * 10 degrees from 30k through switchover. And that's in general. I try to keep the rate of ascent about 100 m/s or as close to that as I can manage through the ascent, and will adjust my nose angle as needed. I'm assuming in FAR that this is not how I want to do things, that I'm going to want to keep the AoA closer to 23 degrees throughout the flight. Does that sound right? I'm assuming that landing on the runway will still be the same; deorbit so that your periapsis is 44k over KSC and take it on in the rest of the way once you're subsonic. I've heard that in FAR, you need to do a series of turns to bleed off speed. I'm curious if there's a way to set up an "airbrake" in FAR as well. Also, what exactly is the function of flaps and spoilers? -ROCKET DESIGN- Here's where I think I may get into the most trouble. I usually design my boosters asparagus, and I know that FAR doesn't like short rockets with the CoM too far up the rocket (stock is that way too, but I imagine the effect is more pronounced). Anyway, I use Temstar's guidelines to build asparagus: - Assume a 15% payload fraction to calculate the mass of the rocket. - Assume a 1.65 launch TWR to calculate the amount of thrust needed for the theoretical rocket mass. - Assume 22% of that thrust will need to be in the core, and divvy the rest of it out to the boosters (I almost always use 6 boosters, which works out to 13% of the thrust per booster engine) - Select the rocket engines necessary to produce the required amount of thrust, adjusting the thrust limiters as needed. - Subtract the payload and engine mass from the theoretical rocket mass, and an additional two tonnes for "incidentals" (seperatrons, decouplers, a probe core for the core and battery power, etc.) - Divide the remaining mass by 7 to get the full fuel tank mass per stack, and find a tank or set of tanks that puts me in the ballpark. - Build the booster based on the figures calculated and make further adjustments to the thrust limiters. That typically gets me a 4,500 m/s booster with a launch TWR of 1.65. In FAR, I imagine I'll have to go back to serial staging, which I can do but which gets to be such a bite. I know that I only need 3,500 in FAR; is 1.65 still a good launch TWR? Are there any other worlds where there's a difference in launch TWR? -ROCKET FLIGHT- A typical launch for me goes like this: -Straight up to 10k -Nose over to 45 degrees and hold until 35 seconds to apoapsis. -Nose to 20 degrees and hold until 45 seconds to apoapsis. -Nose to 10 degrees and hold until 55 seconds to apoapsis. -Fly along (or even below) the horizon until MECO. Now, I've heard that the nose over needs to be gradual, that a sudden swing to 45 degrees will result in a tumbling rocket. Where would you all recommend the turn commence, and how gradual does it need to be? That's pretty much all I'm going to ask about for now. One final question - are there any good tutorials out there for those who, like me, are taking the plunge, and need to unlearn a few things? Thank you all in advance for your replies.

36 tonnes according to the wiki. You can get that into space with stock aero with a craft that looks like this... That was a RAPIER craft IIRC...I might try again with Turbojets. You know, see if I can come up with something a little less oooogly.

Spent a fair portion of yesterday afternoon buttoning up some of my outstanding Minmus contracts. First of these was to put a satellite into a tundra orbit - that was fun; getting the low end of the orbit to an acceptable tolerance was tricky work but I was finally able to get it there after a few tries. Made some pretty good coin on that mission, especially considering the probe used was a Barn Owl (i.e. delivered to LKO initially via spaceplane). Next up was the landing of a new ground base on Minmus. That one nearly met with disaster; I got the distance for the suicide burn a little too good - touched down at 2 m/s and I didn't reduce the throttle because I thought I was about to crash, and by the time I reacted the craft was already heading back up. Luckily I got the engine shut off before it picked up a good deal of velocity, and about a minute later it touched down safely. Got the pilot out and planted a flag - three missions complete. At this point my program is flush with cash, a little over √2,000,000. I've still got three buildings left to upgrade to Level 3 - the VAB, the Tracking Station and the R&D facility. I'ma thinking I'm going to save up enough to get the R&D facility up to snuff. It's probably help if I stopped accepting Duna/Ike missions though; it's still going to be a bit before I can convert those into money.

Well...if I was designing this with stock aero, I'd say the first issue is insufficient thrust. A 211 tonne craft would need 15 Turbojets at a minimum (and that's pre-nerfing, unless it's specifically B9 where Turbojets become largely worthless and not specifically FAR in and of itself; I get the mods I don't use mixed up occasionally). You're using FAR, so I don't know all the rules, but that is something worth considering. The big thing I'm seeing is the position of the CoL relative to the CoM. It's behind, which is good, but it's also above the CoM. Both positions in and of themselves add to the craft's stability - which means the tendency of the craft to pitch downward. Your craft is quite stable, so I'd wager it's quite controllable once you can get it in the air, but one of the side-effects of a stable craft is a high takeoff speed. You might try reducing the upward sweep on the wings. Myself, I think the MOAR ENGINES solution is sound; folks with more FAR experience (read: any FAR experience) might tell you different.

Took out one of my Barometric 7 ground survey planes to hit two pressure survey contracts on the far side of Kerbin. Was dismayed to discover one of the data points was in the water; despite having VTOL capability the plane is actually a pretty lousy VTOL. After about half a dozen failed landing attempts, I gave up and decided to try to pick up the last data point of a previous mission, where really all that happened was a botched landing. Landing went off without a hitch this time around. Went ahead and got that contract buttoned up, then flew back to KSC. Wound up circumnavigating Kerbin in the process; made it back with a 17% fuel reserve.

Go to the Tracking Station and activate the Flags button there; anything you want to see in the map screen MUST be activated in the Tracking Station, otherwise you're out of luck. Don't know if that's an intended feature or a bug; it's annoying either way.

Not much accomplished yesterday - landed the Barn Owl launch vehicle from the previous evening with no issues. I finally decided to go ahead and build a pair of marker rovers for the two ends of the runway, though; got tired of sticking a powered probe core on the Launchpad so I'd have a point of reference every time I wanted to land a plane. The Barn Owl probe it delivered to orbit was sent towards the Mun to fulfill a contract. I spent most of the rest of my playable time working on a 20-Kerbal, lab-equipped Mun base (for a contract) and the launch vehicle necessary to deliver it. Really should've tried to deliver it via a plane; it's been a bit since I've shot for a 200 tonne craft, though. Still over √200,000 as it is; since the booster is non-recoverable, that's really going to cut into the profit margin. Anyways, I did get the initial craft up...only to realize I'd forgotten to attach solar panels. Big facepalm moment there. Reverted the flight, so nothing lost; still didn't have time for a re-launch, so I'll be doing that tonight. Meantime I think I'll see about building a 200-tonne spaceplane...

I've been to both poles of Kerbin, and have returned the craft to KSC both times. I use stock aerodynamics. I can tell you this - you want to be using Turbojets (you can travel faster the higher up in the atmosphere you go, and the Turbojet is definitely a high-altitude engine), and you won't need much more than a single Mk2 Liquid Fuel tank for the round trip. Maybe the extra few units you'd get from a pair of Nacelles, and that's only if you don't feel like draining out the things. Seriously, go with the Turbojets; you can make either pole inside of 15 minutes if you do.

I would suggest to anyone who has had headaches with this particular potential issue to use the Intake Build Aid mod. It does the rearranging for you automatically at the push of a single key. It's is extraordinarily useful in that regard. That's really the only thing I can add here; I don't know enough about FAR to say one way or the other. I know enough to know that red numbers are bad; that's about it.

Didn't have time to do much last night - had time enough to put a Barn Own probe into orbit and that was it; didn't even have enough time to go ahead and land the launch vehicle. Textbook flight up. Almost made the ascent entirely on jets; by the time of flameout I was at a 90x35 orbit. Still had to go a little ways on rockets - I was too low into the atmosphere and ascending to slowly at flameout, so the drag force was pretty substantial. Still made about a 78x78 orbit when it was all said and done. Tonight's activities will begin by landing the plane and then taking stock of the current contract set.

Do you use KER? If so, look for a figure on one of the displays (I think it's Surface) labelled "Atmospheric Efficiency". It should be a value expressed as a percentage. When your craft is travelling at the current terminal velocity for the altitude it's at, that value will be right at 100% (or close enough to it to spit). Much below 100% and you're losing delta-V to gravity; much above 100% and you're losing delta-V to drag. If you're not using KER, well, it can be done by hand - the formula is: V = sqrt ((2Mg)/(rho*A*Cd)), where V is terminal velocity, M is the mass of the craft, g is the acceleration due to gravity, rho is the density of the atmosphere, A is the "projected area" of the craft and Cd is the coefficient of drag. Trouble here is that g and rho are both dependent on altitude, and since you're in craft burning fuel, M is also time dependent. You'd be looking at a really nasty differential equation. But it is an option.

http://forum.kerbalspaceprogram.com/threads/52080-Basic-Aircraft-Design-Explained-Simply-With-Pictures keptin pretty much answers all four of your questions in one fell swoop. Since you're using FAR, the principles are all the more accurate.

Try SCE to Auxiliary. If it makes you feel better, replace "RAPIER" with "cluster of one Turbojet and three 24-77s" and "13 tonnes" with "15 tonnes"; the rest of the guidelines apply. That guide helped me go from building good ocean-bound lawn darts to building flying parts machines that deliver Munar landers to orbit and bring them back down again... Myself, yesterday I rescued Nelily from orbit. Got another Scientist for my troubles. That seems to be the only way to get those guys in my current Career save - the only Kerbals that ever show up for recruitment at KSC are Pilots and Engineers. I also adjusted the design of a VTOL I've been working on. I think I need to go reference DocMoriarty's guide again; I'll just put it that way. Though I am hopeful I'll be able to deploy that craft to run some surface pressure surveys soon.

This tutorial will give you some good general guidelines for catching rocks, though in your case if it's really only 40,000k from Kerbin then it's already in Kerbin's SOI and you've got comparatively very little time left with which to affect an intercept. The mass of a Class C rock indeed ranges from between 42-190 tonnes, with ninety tonnes a good figure for planning purposes (for reference the mass formula for rocks is e^(1.5x), where x=1 on average for Class A (it ranges from 0.5 to 1.5), 2 for Class B, 3 for Class C, 4 for Class D and 5 for Class E). The dinky little probe that Claw uses in the tutorial can easily catch a Class A or B on its own; I've delivered it to LKO before via spaceplane (it is a case where replacing the 909 with an LV-N gets you more thrust and more delta-V, incidentally). C is a little bit out of the range of that simple craft, but not much. You could still attempt an intercept in Kerbin's SOI in the manner indicated in the tutorial I've linked you to, though since you're closer to the body that both your craft and the rock are orbiting (i.e. Kerbin), you'd have to book it and not miss on the first attempt - otherwise the rock would likely get away from you and ultimately land and tear up somebody's fender. Since you asked, aerobraking is possible with rocks - you just treat them like any other craft. Since you're using B9, and assuming you've got the latest version, you're also using FAR, with which I'm not familiar (been thinking about switching but haven't done it yet). That wide, irregular surface is going to generate a fair amount of drag, so I'd recommend orienting the rock so that your capture probe can push it prograde during the aerobraking process. Just in case; like I said, I don't really know enough about FAR to give sound advice there.

What Slashy said. So for your eight tonne aircraft, you'll want to use one Turbojet as your main engine and a combination of wing parts that add up to a lift rating of "eight". Delta Wings and Wing Connector A/B are "two" each, so you'd want four total of those parts. Some of the wing parts actually result in better "lift per tonne" than others (the Deltas and Wing Connectors are actually really lousy in that regard); for example the old-style Swept Wings are actually really decent wing parts, they're just hard to stick control surfaces onto.

I mentioned following formulas for the soup - here are the ones I go with: *10 tonnes takeoff mass per Basic Jet (Basic Jets for airplanes/VTOLs only), 13 tonnes per RAPIER, 15 tonnes per Turbojet. *.03+ Intake Area per engine (equates to 3 Ram Intakes) regardless of engine type. (If you look at the engine setup on the Bat, that's how I usually build "engine units" - start with the Nacelle). *1.5 units of SAS per tonne of takeoff mass. *1 unit of lift coefficient per tonne of takeoff mass (For example, if you have a four tonne craft, you only need a pair of Delta Wings - each has a lift coefficient of 2) *40 units of Liquid Fuel per tonne of takeoff mass and 25 tonnes of Oxidizer. *Plan for a payload fraction of 25%; a crappily-designed plane will still usually achieve at least that. Now, lemme explain that in action. Payload is anything you're hauling up that doesn't help the plane fly itself up into space (like say you want to go interstellar with your craft so you give it a pair of nukes and dedicated fuel supplies; that would count as payload). For the Bat, that would be the 18 tonne lander it hauls up there. So I multiply that mass times 4 and get the estimated mass of my plane - 72 tonnes. I then pick an engine array that is capable of supporting that much mass. For 72 tonnes, that would either be 6 RAPIER engines (72/13 = 5.538) or 5 Turbojet/24-77 clusters (72/15 = 4.8). I went with Turbojets on the Bat because it's a career-built plane and I only have access to the Level 2 R&D, so RAPIERs are still locked. Plus truthfully I think I like the Turbojet/24-77 combos better, especially since I started using Intake Build Aid (that mod saves some serious headaches). With my engine setup selected, I assume the plane will have the maximum mass the engine units can support, and use that to determine how much fuel I'll need. For example, I have 5 turbojets, so I'll assume the plane will be 75 tonnes at takeoff. That means I need 75x40 = 3000 units of Liquid Fuel and 75x25 = 1875 units of Oxidizer (I think you can actually get away with a mere 10-15 units of oxidizer per takeoff mass with a Turbojet setup but I need to do more experimentation with that figure; your oxidizer needs will depend a lot on the speed at which you switch over to rocket mode, and the 25 per tonne figure originates from use of RAPIERs with a switchover Surface speed of roughly 1750 m/s). I then go about selecting a combination of fuel tanks that will give me at least that calculated amount. From there it's a matter of adding the wings, gear, ASAS (for 75 tonnes, you want 112.5 kN of SAS, so 4 Large ASAS Wheels, 8 Stabilizers or 24 Wheels or a combination thereof), command core, and power generation. I set things up so the plane's CoM doesn't shift, the CoT is aligned with the CoM and the CoL is slightly aft but aligned with the CoM. I do use canards; the soup likes canards. Last things I do before launch are to unlock the steering and disable the brakes on the nose gear and to make sure I've got any fuel lines I'm using correctly configured. I set up my action groups generally as 1 = toggle jets, 2 = toggle rockets, 3 = toggle intakes, though nothing says you can't set the jets and intakes onto the same action group. Building an engine unit cluster is simple - you start with the Nacelle on your craft's centerline, put the Turbojet on the back, then turn on radial symmetry, add 2-4 24-77s (this one I'm fuzzy about; I think you could get away with 2 but I use 4 in case I botch the ascent; by the time of switchover a Turbojet is usually outputting about 60 kN anyway, so 3 is a good balance there), and then remove the Nacelle. Go back to mirror symmetry, put the nacelle along side your fuselage, add a tricoupler, and add a Ram Intake to each. When you need to copy it, hit ALT and click the Nacelle. Works well enough for initial placement purposes anyway; when time comes to re-order your intakes/jets, you can just pick them off one by one and then reset them as needed (to minimize the issue of assymetric thrust when the jets start flame out). Or you could just install Intake Build Aid and hit the magic button prior to takeoff, which will do the same thing for you automatically. Seriously useful. Anyways, those are the formulas I follow and the process I use when I go about designing a plane. Bear in mind that the formulas work for the soup; I haven't explored FAR enough to know if they all still apply or not, and it's something that I needs to investigate given the changes to the stock aero model with the upcoming 1.0 release of KSP.

Still not taking off......what's the mass of your craft? You've got the KER display up in compact mode in your screenie. Two RAPIERs oughta support up to 26 tonnes of takeoff mass, so I'm guessing that you don't have enough lift-generating parts on the design for its mass. As a rule you want the sum of the lift coefficients of all your lift-generating parts to be roughly equal to the mass of the craft in tonnes (a 26 tonne craft would need a total combined lift coefficient of 26, the equivalent of 13 Delta Wings; you could get away with a 1:1.15 ratio, which comes out to 12 Deltas, but the 1:1 is easier to remember). I'm also seeing a grand total of two Elevons on that craft and small ones at that...Elevon 1s, I believe. You might not have sufficient pitch authority to bring the nose up. Any of those problems could be cropping up with your design here.

... ♫ and you can't take the sky from me. ♫ Myself, I just did a aerial survey for pressure readings. Naturally I botched the plane landing of the one I had to try to get on the ground to get full credit for the contract, so I get to try for that one again. Still have yet to make a VTOL survey craft that flies well in VTOL mode, this despite following the usual guidelines.