GoSlash27

http://s52.photobucket.com/user/GoSlash27/slideshow/KSP/KrakBadger Well... you asked haha -Slashy

I had one around here somewhere, but that was for .25. I'm due to make a new table for .90, so I guess that'll give me something to do today. Your most efficient wings are (in order) #1 the strake #2 the structural "D" #3 the old swept wing. I'll put together a new table that compares all the wings. Best, -Slashy

The reason for this is because incorrect models tend to diverge from empirical results the most at low t/w ratios. If it's incorrect at the bottom end, then the slopes will be incorrect at the higher end, and anything inferred from them (such as ideal t/w for a given engine) will yield incorrect answers. This would only hold true for a medium-low Isp engine on the Mun. For a low Isp engine on Tylo the DV efficiency at 1.0 t/w can exceed 75%, while a high Isp engine on Pol might only achieve 32%. Regards, -Slashy

Cyberdragon, You're not "pathetic", you're just losing focus before you get a chance to learn about concepts that are vital to reaching other bodies. Delta-vee is important, and you need to understand it. Transfer windows are important, and you need to understand them. Maneuver nodes and burn directions are important, and (yeah, I know... but still) you need to understand them. Without a basic understanding of these concepts, you're not going to be able to intercept other bodies. Once you understand them, it all gets *much* easier. You should not be learning about how to get to other planets right now, you should be learning about these concepts. I believe Manley also has videos on these concepts, and if they're like his other videos, they should help you tremendously. tl;dr Go back and watch the video again. When he starts talking about something you don't understand, *stop* Go and watch his video on whatever it is you don't understand. Once you've got it, pick it up where you left off. Good luck! -Slashy

I think I mentioned this one somewhere else, but for epic launch/ reentry music I recommend two steps from hell.

No, wings work the same forward or backward. I can't say what will happen after the next update. Cheers, -Slashy

Fire-Dragon, You don't need a bigger spaceplane to get to Laythe, you need a *smaller* one. For the amount of mass you're lifting, you've got way too many turbojets and way too many wings. You need just enough wings to get you above 32km altitude and just enough turbojets to overcome drag through the 25-32km "wall". For the top-end speed portion of the flight, more turbojets don't help you to go faster, they're just dead weight. Same for wings; they help get you over the 25-32km "wall", and after that they're dead weight. You really only need 1 turbojet for each 15 tonnes of aircraft, 4 radial intakes per engine, and enough wings to generate 1.0 lift coefficient per ton of aircraft. If you build to those specs, your spaceplane will easily achieve orbit and be light enough for your LV-R to do it's thing. This plane is designed to shuttle Kerbals to a station in LKO and back to KSC, but you can see how much payload that is. That 12t plus the fuel to feed the LV-909 buys you a lot of DV with an LV-N. For wings, the delta wings are the least efficient choice (somebody said that upstream; good advice). The ideal wings are the strakes. For engines, I don't recommend RAPIERs for any reason other than cool factor. They stop producing thrust 200m/sec earlier than turbojets and it's less thrust. tl;dr Don't think "moar boosters", think "moar efficient". Best, -Slashy

Arugela, The center of lift doesn't have to be perfectly aligned vertically with center of mass to get high- speed stability, but it helps. Getting that is just a matter of adjusting the wing attachment height and how much the wings slope up from the fuselage. From what I'm reading here, it seems to me that your problem isn't one of static balance, but rather drag distribution. Some parts in stock KSP have higher drag than normal. Especially intakes. Other parts can have lower drag than normal, such as wings. Control surfaces can have anywhere from negative drag (infinigliding) to high drag, depending on how they're aligned at the moment. A lot of people don't realize this, and it leads to a lot of frustration with planes that seem to handle fine... and then become completely unflyable at high speeds. So here's what you do: *Intakes go in the back of the plane. Use radial intakes because they're convenient for this. *If you use control surfaces in the back of the plane, also use them in an equal amount in the front. * Don't try to use control surfaces to crutch an unbalanced design. For example, don't build a nose-heavy plane and then slap a canard on it. Your plane will *look* balanced, but it'll try to fly backwards at high speed. *Build the plane without control surfaces and get it balanced, then add control surfaces in such a way that it remains balanced. If you do this, you will have a plane that doesn't flip out at high speed and during reentry. Best, -Slashy

Fire Dragon, It looks to me like you've got too many wings there and the induced drag (even at 35km altitude) is too much for the LV-N to overcome. You really only need 1.0 Cl per ton of aircraft to get you to the jump-off point to orbit. You also wouldn't really need 4 turbojets for this job and are you remembering to close your intakes when transitioning to the LV-N? http://forum.kerbalspaceprogram.com/threads/102182-So-you-want-to-build-a-space-plane Best, -Slashy

http://www.tinyvital.com/Misc/Lawsburo.htm Moore's laws of bureaucracy dictate that goals only get more expensive and difficult to achieve as bureaucracies increase in size (whether government or private sector), so no... a moon- shot would be more expensive and difficult today than it way back in the '60s and will be more difficult and expensive tomorrow than it is today. Best, -Slashy

Don't I know it! *rueful grin*... How did the elapsed time stack up? -Slashy

I ran a new mun test, and this time I was *way* under the model's prediction (which is good). At launch: M=2.43t T=4kN Isp=290s t/w=1.01 alt=2,361m t=30.00 At circularization: M=1.70t Vo=547.5 m/sec alt=10,009 t=52:31 DV expended= 1,017 m/sec efficiency= .538 st= 22:31 According to the contour plot I would've expected 63%, and the terrain wasn't even awful this time. Hmm... -Slashy

And Mun test results are in. At launch: M=2.43t T=4kN Isp=290s t/w=1.01 alt=2,361m t=30.00 At circularization: M=1.70t Vo=547.5 m/sec alt=10,009 t=52:31 DV expended= 1,017 m/sec efficiency= .538 st= 22:31 If I read the chart right, I way *under* performed compared to the chart this time. Best, -Slashy

Eeloo test results are in, and if I read the chart correctly, I didn't outperform the model. At launch: M=2.35t T=4kN Isp=290s T/W= 1.01 alt=1,971m t= 04:00 At circularization: M=1.71t Vo=568.7m/sec alt=20,048m t=31:48 DV expended= 905 m/sec efficiency= .629 et=27:48 On to the mun! -Slashy

direct link http://i52.photobucket.com/albums/g13/GoSlash27/CP2D_zpsdad6f965.jpg Best, -Slashy

Okay, I'll make it mu then. Best, -Slashy

Okay, my Eeloo results are in, and it blows my theory out of the water. Looking at the contour plot, it *precisely* matched what Arkie's model predicts. Initial state: 2.35t launch vehicle with 4kN/ 290s Isp engine. t/w=1.01 alt=1,971m time= 04:00 End state: M=1.71t V=568.7m/sec alt=20,048m time=31.48 DV consumed= 905m/sec efficiency= .629 et= 27:48 If I'm reading the table correctly, arkie's model predicts 63% efficiency, so right down the middle. Whatever the deal is, it doesn't seem to be the sidereal rotation. Best, -Slashy

... but of course then we'd have to define mu as G*M. I don't mind doing it (it's your plot). I can do either, so just let me know. Best, -Slashy

arkie, I can check and see if my original test launcher is still in the same spot. I never recorded that during the first batch of tests. If it's not, no worries. I'm gonna rerun the test. *edit* update: Sorry, the original lander is gone. But as I said, I'm gonna rerun the test. Best, -Slashy

arkie, Not a problem. I'm as interested in seeing where this winds up as anybody Best, -Slashy

Direct link http://i52.photobucket.com/albums/g13/GoSlash27/CP2C_zps4c88655e.jpg

So... Yeah, I could confirm that I didn't go anywhere at first during my tests. I didn't record launch altitude or flight duration previously, so I'll rerun it. I'm going to run 2 launches today to try to pin down how much of the error is altitude (if any) vs. sidereal rotation. I'll do another launch from the Mun (rotation 9 m/sec), and one from Eeloo (68m/sec). Both as close to 1.0 t/w as I can get them. Best, -Slashy - - - Updated - - - Yessir. I'll get on that right away. Best, -Slashy

Sorry, I'll get to your question in a moment. Just wanted to post this for you first. I hope that works for you. Let me know if there are any errors.

Oh, okay! That explains it. So at the moment, I have exceeded the predicted DV and you haven't. And of course LD won't accept my results. I propose a test: 1.0 t/w launch from Eeloo using whatever engine. If my suspicion is correct, I'm thinking everybody's results will exceed the predictions of both models by a wide margin. Best, -Slashy

Actually, I do and I always have (except where I can achieve higher t/w for free) for this very reason. I came to this conclusion but never had hard numbers to go from before. Hopefully I can work with all this data and boil it down to a much simpler set of recommendations; like "for this engine, it's not worth it to add engines beyond such-and-such a t/w". Gonna take me a while to crunch the numbers, tho'. Best, -Slashy