capi3101

Not much I can add here - your options are to A) send a craft with an available empty seat to rendezvous with Jeb and jetpack him over, send a ship to capture Jeb's pod (with the problem that you won't be able to warp without risking both craft, or C) get out and push. It really depends on if there's any science aboard the pod that you want to keep. I will note that if the ship has no power, you're probably going to have a tough time firing off its chutes; if it were me, I'd bite the bullet and go with A).

Career mode - decided to try for a Tylo intercept with my Jool probe since I was out to it's orbit at apoapsis. In the course of adjusting my phase angle I would up getting a Vall encounter, so I went there instead. Wound up with a equatorial orbit (okay: 4.9 degrees inclined, still close enough to put it on the Vall ribbon). Shot another probe into a polar Dres orbit. Gained lots of science from both missions - picked up Advanced MetalWorks and Large Electrics. Could've picked up Very Heavy Rocketry but decided the BZs were higher priority. Got Jeb back up from Duna's surface; getting ready to send him, three goo containers, a materials bay, a surface sample and a hell of a lot of EVA reports home. Hoping for some big returns on that mission.

Sure thing, but Jeb's driving, so I'd expect it to explode once it arrives......or before it arrives.......you know what? Just expect it to explode......

True - and the easiest way to do that is with the formula found here: For example, say you've got a Skipper with 4 LV-T30s. Skipper outputs 650 and has an atmo Isp of 300; ratio of output to Isp is 650/300 = 2.167. LV-T30 outputs 215 and has an atmo Isp of 320; it's ratio is 215/320 = .671875. The total thrust for a Skipper and 4 LV-T30s is (4*215)+650 = 1510 kN, and you'd divide that by (4*.671875)+2.167 = 4.854167. 1510 / 4.854167 = 311.073, which is the Isp you would use in that case (you could round it down to 311 if you'd like). Been a while since I looked at that challenge - looks like I got knocked off the leaderboard and didn't realize it...well, that sucks.

http://www.kerbalmaps.com/ 20.5829 N x 146.5116 W To my knowledge, there are no mods that will let you launch from KSC2; someone with more knowledge of the available mods may know differently.

It's not necessarily the case that larger rocket = higher payload fraction. Check out some of the submissions in the Payload Fraction Challenge; some of those designs are pretty small. Light payload = 48-7S as an asparagus booster; no joke. LV-T30 and LV-T45 have the exact same Isp ratings; just thought I'd mention that...

Edit your initial post; the tab to change the thread status is there.

Would you take a parts list as a submission? PAYWAD: Mk1 Lander Can x1 Clamp-o-Tron Sr. x1 Z-1K Rechargable Battery Bank x1 Gigantor XL Solar Array x2 FL-T800 Tank x1 LV-N Atomic Rocket Motor x1 Inline Reaction Wheel x1 PB-ION Electric Propulsion System x1 PB-X50R Xenon Container x2 Such a craft would have 4,484.208 m/s of delta-V from its NERVA and its ions would provide 360.238 m/s of delta-V, for 4,844.446 m/s total. Eleven parts with a mass of 9.19 tonnes. Now for the booster: BOOSTER: RC-L01 Remote Guidance Unit x1 OX-STAT Photovoltaic Panels x8 Clamp-o-Tron Sr. x1 Z-4K Rechargable Battery Bank x1 Mk2-R Radial mount parachute x16 LT-2 Landing Strut x8 RV-105 RCS x12 Rockomax "Mainsail" Liquid Engine x3 Rockomax Jumbo 64 Fuel Tank x9 That's 59 parts plus 32 struts for 91 parts, plus 11 for the payload is 102 parts total. Booster TWR is 1.288 and it has 4,549.405 m/s of delta-V. This isn't a space plane, obviously, but it is an SSTO. Subtle difference between the two terms and all that. I dunno - I'll have to build this myself to check its viability; sixteen radial chutes and eight lander legs isn't going to cut it, I think. But it's a start. Maybe with a deorbit on RCS and saving any remaining fuel in the tank to slow for chute opening. Maybe if the legs were extended out with I-beams; they'd have to stretch past the engine bells. Hold on this as a submission until I get pics.

Asparagus is your best bet for an efficient launch - and Temstar's got formulas for that here. You can usually get about a 15% payload fraction with asparagus. Now, recently I've had some discussion on a different thread regarding serial staging, and one of the designs we came up with for a five tonne payload would up with a 10% payload fraction, if that's something you might be interested in (simplicity of the design and all that). Asparagus is more efficient, of course. SSTO (a single-stage booster) is also possible, though those aren't efficient at all - they usually run around 4% payload fraction. For a 3.3 tonne payload, though, they're viable and you can't beat the part count (a consideration for folks with slow machines) - try a Mainsail, Rockomax Decoupler, two orange tanks and an X200-16. 9 struts to stabilize = 14 parts, 4550.664 m/s and 1.398 TWR. Those require you to keep a hand on the throttle. Gravity Turn: If you don't have KER, start by turning to 45 degrees elevation on course 090 when you get to 10,000 m. Watch your ascent in the map view. When you get to the point where you are at least 35 seconds from Apoapsis, turn your ship to face your prograde marker and follow it down. If you go below 30 seconds to apoapsis, return to 45 degrees elevation and stay there until it goes back up past 35 again. Once you're a minute to apoapsis, turn to burn along the horizon and keep doing so until your apoapsis is about ten kilometers past where you want it (you'll probably be still in atmosphere at this point, the extra margin will help with losses due to drag). While you're doing this, watch your gee meter - if it climbs out of the green zone, throttle back until it's back in there. Preferably you want the gee meter needle to be right at the top the entire way up. Those are good general guidelines if you don't have mods to handle your ascent.

I would integrate the equation, but Calc IV was fifteen years ago and I haven't had much use for it sense (lousy job market). I may look into the derivation of the rocket equation itself and see if there's anything usable. And then I'll have to look into how to do integration again. Meantime, I've worked up a chart to solve the earlier equation I posted for delta-V bonus from the Oberth effect for a set of different altitudes and differing transfer delta-Vs: Hopefully that's of some use too. EDIT: Terms on the chart - that might be needed. GM is Kerbin's Gravitational Parameter, R-SFC is the surface radius of Kerbin, V-ESC is escape velocity at the listed set of altitudes, V-ORBIT is the orbital velocity at the given set of altitudes (which I use for the initial velocity in the equation). V-FINAL is just V-ORBIT plus the transfer delta-V requirement for the listed destinations, and there's an array of those values (MATRIX). DELTA-V REQ., the delta-V required, is the solution to the equation; this is the amount of delta-V that must be applied to acheive the actual delta-V necessary for the transfter, and OBERTH BONUS is just the difference between the two values.

You should try a Skipper and four LV-T30s set radially. You can use Tail Connectors or even Modular Girder Segments; just set them flush against the sides of the tanks and slap the -30s on the bottom. Both of those parts have fuel crossfeed, so you won't need fuel lines, though you may have to turn on parts clipping in editors (ALT-F12 to bring up the debug menu) to get them to go on (the tops of the engines may overlap). Presto - an engine cluster with slightly more thrust and better Isp than a Mainsail, at the cost of a little more weight and a few more parts. It makes for a good workaround while you're saving up the Science you need for the Mainsail. No Skippers? Try 6 LV-T30s set radially (same method) with an LV-T45 in the center. Slightly less thrust than a Mainsail and at least three tonnes heavier, but better Isp and still a good workaround - and a possibility at a much lower tech level.

In practice (for me anyway), I wait until the target craft is around 500,000 meters uprange of KSC (this involves going to my KSC ground beacon, targeting the craft, and waiting until its distance is around 500,000 and still decreasing) before launching. That generally works and it's a good ballpark figure for targets between 70,000-120,000 meters or so (I occasionally wait to 475,000 for lower targets, and it's never a precise value).

Finally relaunched my Constellation missions to Duna. Still trying to figure out why the crew/habitat mission had absolutely no problems getting an intercept despite being 0.08 degrees off the phase angle, which the KRV/Cargo module (which was launched exactly at the phase angle and exactly at the ejection angle) required a major radial-out burn - I followed the directions Protractor gives to the letter. Had to cannibalize fuel from both modules as it turned out before I finally got an intercept. Probably will have to do more cannibalizing when that mission gets to Duna. Made the apoapsis burn of a bi-elliptic transfer for a probe to heliosynchronous orbit. Periapsis burn will be in a little over 200 days. Shot a probe to Dres (first time to Dres!!) and got it into a near-polar orbit (102 degrees). Debating what else I want to do with that probe; I might just want to leave that there. Similar note: I finally got a Sandstone Yoke probe-delivery system to Jool (second time to Jool! No better than the first!!). This one has mini probes attached, so my original "Jool orbit and atmospheric dive" mission is back on.

Redo mission is underway. Still en route at the moment. Still trying to figure out why the KRV/Cargo module mission, which was launched at exactly the right phase and ejection angles, had such a hard time reaching Duna when the crew/habitat module (launched early - that mission had more delta-V in the budget, which is why that decision was made) - got it after the first correction burn. Also did the apoapsis burn for the telescope; that went well and the Kerbolar periapsis is now in the target range. 200 days to periapsis. Did one other thing last night...

Well, first off, the bonus dV from Oberth I calculated was only 358.615 m/s, and that was at 70,000 meters. Second, the formula for Oberth effect does not take into account the rate of acceleration, just the initial velocity, final velocity and escape velocity. All three of these values (and thus the Oberth effect bonus) should be the same for all craft that burn the same amount of delta-V at the same altitude, regardless of their TWR. What would affect the bonus is a slower initial speed, i.e. starting the burn with a higher periapsis. The formulas I used assume an instantaneous burn occurring right at periapsis; same as the maneuver node system KSP uses. Granted that's an incorrect assumption and may have an effect on what we're talking about. I'd wager the correction for that assumption would involve a pretty nasty looking differential equation; I could be wrong about that, of course. I'll do some homework and get back to y'all about that.

Thought of another one - when you need something that is definitely pointed prograde. Case in point: the Scorpio capsule I'm using for the Constellation challenge has room for six Kerbals; it does this by mounting Mk1 Lander Cans on the sides of a Rockomax Adapter. This gives me room for six at a mass comparable to a Mk1-2 Command Pod, but the problem is that none of the cans are oriented in the same direction as the rest of the craft. So there's also a probe core, and it's from that point that I control the rocket.

Okay... here's my array from last night, adjusting for the higher gravity for TWR (at 70,000 meters, g = 7.867 m/s2) 1 Engine: 3945.897 m/s, TWR = 0.188 2 Engines: 3585.303 m/s, TWR = 0.350 3 Engines: 3361.88 m/s, TWR = 0.498 4 Engines: 3165.016 m/s, TWR = 0.633 6 Engines: 2833.879 m/s, TWR = 0.867 (had the TWR wrong last night - should've been 0.957; six nukes output 360 kN, not 300) Let's normalize those delta-V values, using the three engine case as our baseline (remember, we designed the three-engine case to give us almost exactly what we needed for the whole mission): 1: +584.017 m/s 2: +223.423 m/s 3: +0 m/s 4: -196.864 m/s 6: -528.001 m/s Once again, we're starting with orbital velocity = 2,295.86 m/s and escape velocity at that altitude is 3,246.86 m/s We want to go to Eve; that takes 1,030 m/s (from the example last night), and we're steely-eyed enough to get it perfect right at the periapsis. So we want our final velocity to be 3,325.86 m/s (2295.86 + 1030 = 3325.86). So we have: dV = √(3325.86^2 + 3,246.86^2) - √(2,295.86^2 + 3,246.86^2) dV = 671.3851028 m/s If we apply 671.385 m/s of delta-V at a 70,000 meter periapsis, we get 1,030 actual delta-V. So the Oberth Effect bonus in this case is 358.615 m/s (1030 - 671.385). That's applies regardless of the number of engines involved. If we apply that as a bonus to our normalized values above, we can see that we'll still come out ahead with four engines, but by the time we get up to six engines we've given up too much delta-V via the spacecraft's mass to make it worth our while. I may have misunderstood what the issue is regarding the usefulness of the Oberth effect; I think I'll go re-read the posts on this thread. Hopefully this has been helpful to some of y'all, at least.

I'm ashamed to admit that I have ready access to both......

http://en.wikipedia.org/wiki/Oberth_effect http://www.projectrho.com/public_html/rocket/mission.php -- Lucky us, I found a formula that calculates the Oberth delta-V bonus. Maybe it's just the way I'm reading it, but it looks like for gameplay purposes you'd want to place your periapsis right over the spot you want to eject from, and you want it to be at 70,000 meters on the nose at that point. Orbital velocity at 70,000 meters is 2,295.86 m/s; that's roughly as fast as your speed can initially be without dragging the atmosphere (technically atmosphere ends at 69,078, thus 69,079 is as low as you can go and the velocity is 2,297.46 m/s, but I don't see anybody really wanting to get down that close). Escape velocity at 70,000 meters is 3,246.86 m/s - that sounds about right. And the formula is: dV = √(Vf2 + Vesc2) - √(Vh2 + Vesc2) Where Vf is final velocity, Vh is initial velocity, and Vesc is escape velocity. dv in this case refers to delta-V at periapsis. Spent most of the morning just trying to research this bit; it will take a while before I can work on trying to quantify it. I will need to adjust my case examples to account for the lower starting altitude for TWR. Fun for the afternoon local.

They're generally useful for situations where you don't want a manned pod. Off the top of my head, it's generally better to send an unmanned craft on your first trip to some place you haven't been before, particularly if you're trying not to kill anybody. Another one (and this one is more useful) is debris cleanup - you put a probe core on the part of your booster that does your orbital insertion and a couple of small battery backs. Minimal RCS maybe. Once it's delivered the payload, you can take control of it, turn it retrograde and burn any remaining fuel in the tank to deorbit it (RCS can also be used for this purpose). Beats leaving a giant hunk of crap in orbit, that's for sure. Last night I sent a probe to Jool (first Jool trip!). Brought along a goo canister; got a fair amount of science from the thing.

Basic tips for rovers - build them wide, build them low, incorporate a reaction wheel somewhere into the design, drive around in docking mode (or remap your keys so that you use translational controls instead of rotational controls - which is what you're doing while in staging mode). Encase the critical hardware (command pod, batteries, etc.) in parts with high impact tolerance (e.g. structural panels and girders). If you need additional downforce, try ion thrusters or RCS (ion thrusters have the advantage that you can leave them on without constantly thrusting and they'll last longer, though the weight of the necessary equipment will be significant). Obligatory, now dated screenshots of the Hellhound on Minmus:

Well, thanks. I did the proof of the backwards Tsiolkovsky equation a couple of weeks ago on a different thread. The idea is that given a "target delta-V", you can use it to figure out exactly how much fuel you need. It assumes that a fuel tank of a given mass when it's dry weighs nine times as much when it's full, which is a true assumption for every liquid fuel tank in KSP except for the Round-8 and Oscar-B. Everything besides the fuel tank is "dead mass", mass that doesn't change over the course of the lifetime of the stage. Now, getting a fuel amount that directly corresponds to a combination of fuel tanks is nearly impossible, so what I do is divide the amount I need by .05625 tonnes, the mass of a full FL-T100 tank (the smallest tank for which the basic 9:1 assumption still holds true), and get "FL-T100 equivalents", from which you can get the other tanks (FL-T200 = 1 FL-T100, FL-T400 = 4 FL-T100, FL-T800/X200-8 = 8 FL-T100, X200-16 = 16 FL-T100, X200-32 = 32 FL-T100, Jumbo64 (Orange Tank) = 64 FL-T100). TWR was probably the equation I was vague on, but I assumed everybody knew that one: TWR = T / Mg, with g ≡ (GMplanet)/R2, T being the amount of thrust available (an LV-N outputs 60 kN of thrust at full throttle, of course), and M being the total mass of the rocket (deadmass + fuel). Incidentally, GMplanet is what's known as the "gravitational parameter"; it's just the gravitational constant of the universe times a planet's mass. According to the wiki, this value for Kerbin is 3.5316*1012 m3/s2. It's planetary radius is 600,000 m, and if you do the math you get surface g = 9.81 m/s2. A 100 km orbit is at a radius of 700,000 m, from which I got that 7.207 m/s2 figure. I'm probably not helping matters here, am I? Same here... And here I was thinking that someone would point out that when you send a twenty tonne lander to Eve, it better damn well not still be twenty tonnes when it comes back up...

http://wiki.kerbalspaceprogram.com/wiki/Drag#Drag The game makes the assumption that cross-section is based on mass, so drag should be decreasing at a rate proportional to the decrease in mass.

We can do that real quick. Let's say we've got a twenty tonne lander that we want to send to Eve. Let's further assume we're a steely-eyed missile man that can get that there and back for the exact amount of delta-V the delta-V map indicates; 1030 to get there, 1310 to get into orbit, 1030 to get back (I guess we'll forego aerobraking), so we need a transfer stage with 3370 m/s. We're starting from 100 km above Kerbin; gravity at that altitude is 7.207 m/s2. Let's say our "default case" is going to be three LV-Ns. So we have twenty tonnes payload, let's say a Clamp-o-Tron Senior (0.2 t), three LV-N's (6.75) attached via BZ-52s (0.12), a long girder segment and a girder adapter (.85) that attached it to the booster for launch, and our fuel. We have 27.92 tonnes deadmass, so it works out as: Md = (y-1)x /(9-y), where y= e^(dv / (Isp * go)) and x is the deadmass (This is Tsiolkovsky backwards, making an assumption of a 9:1 mass ratio for fuel tanks). y= e^(dv / (Isp * go)) = e^(3370 / (800 * 9.81)) = 1.53635 Md = (y-1)x /(9-y) = (1.53635-1)27.92 /(9-1.53635) = 2.00638 M = 9Md = 18.05739 tonnes. So we need 18.05739 tonnes of fuel to get 3370 m/s for the default case. If there's .5625 tonnes in an FL-T100, we need 32-33 FL-T100s; 32 FL-T100s equals one X200-32. Let's just go with that to keep it simple - we have eighteen tonnes of fuel wet, two tonnes fuel dry, 27.92 tonnes deadmass, 800 is the Isp. Tsiolkovsky: dV = ln((27.92+18)/(27.92+2)) * 800 * 9.81 = 3361.88 m/s TWR = 180 / (27.92+18) * 7.207 = 0.544 Okay. Now for an array of values: One Engine (-5.43 tonnes deadmass, -2LV-N, -2 BZ-52, no girder assembly needed): dV = ln((22.49+18)/(22.49+2)) * 800 * 9.81 = 3945.897 m/s, TWR = 60 / (22.49+18) * 7.207 = 0.206 Two Engines (-2.29 tonnes deadmass, -1 LV-N, -1 BZ-52): ln((25.63+18)/(25.63+2)) * 800 * 9.81 = 3585.303 m/s, TWR = 120/(25.63+18) * 7.207 = 0.382 Three Engines (default case): dV = ln((27.92+18)/(27.92+2)) * 800 * 9.81 = 3361.88 m/s, TWR = 180 / (27.92+18) * 7.207 = 0.544 Four Engines (+2.29 tonnes deadmass, +1 LV-N, +1 BZ-52): dV = ln((30.21+18)/(30.21+2)) * 800 * 9.81 = 3165.016 m/s, TWR = 240 / (30.21+18) * 7.207 = 0.691 Six Engines (+6.87 tonnes deadmass, +3 LV-N, +3 BZ-52): dV = ln((34.79+18)/(34.79+2)) * 800 * 9.81 = 2833.879 m/s, TWR = 300 / (34.79+18) * 7.207 = 0.789 You can put those data in a scatterplot and add a trendline. The formula comes out to y = -0.0006x + 2.3861, where y is TWR and X is delta-V. R2 = 0.9791, so that formula would be an accurate way of calculating delta-V given a set TWR or vice versa 97.91% of the time for this particular craft given our set of initial conditions. It doesn't look like it would ever reach a state of "equilibrium"; ultimately as the TWR goes higher and higher, the delta-V will fall below acceptable limits. Of course, that formula isn't accurate - with zero engines, I have zero Isp and therefore zero delta-V (and zero TWR); that formula doesn't take that case into account. But what do you expect at 11 PM local, anyway?

Succesfully orbited a probe around Eve, then turned around and got one around Jool. This is the first time I've successfully reached the green planet. It's an ugly polar orbit, but an orbit nonetheless.