ferram4

You\'re gonna have to solve this numerically, but I would do this: dx/dt = v(t) dv/dt = (T(t) - ½*m(t)*0.0098*e-x(t)/5000Cd(t)*v2(t) - mu*m(t)/(RK+x(t))2)/m(t) where mu = 3530.35 km3/s2 Then solve it using a standard 4th order Runge-Kutta scheme. It\'ll give you velocity and altitude as functions of time. If you\'re looking for an analytic solution then I think you\'re out of luck. Edit: forgot mass in the gravity force term.

Ydoow, you have my sincerest sympathies. I haven\'t taken O-Chem (and don\'t thank god for being an Aero ), but my friends who have have stated that it is possible to get 20s on tests and still get an A. They described it as painful in ways that I don\'t think can actually be stated here (the forum is family-friendly right?). I\'m gonna bet D for one reason: D\'s get degrees.

@Amram: You are correct in assuming that gravitational forces are only caused by one body currently. However, the main problem with your idea is that it throws time warping out the window. The main reason for the two-body solution rather than solving the N-body problem is the fact that the two-body problem has an exact solution. The worst part of it is solving Kepler\'s equation for true anomaly as a function of time, but once that is done, everything else in the orbit can be calculated exactly at whatever time is desired. The N-body problem would require (for accurate results anyway) that the game never go above 2x warp, or it would ask the processor to do supercomputer feats of calculation for 10,000x warp. Even your simplification would involve this to be calculated for each ship, and would effectively remove time warp from the game or else create huge amounts of lag as the game pauses to compute a few more minutes worth of trajectories. It would also make the game slower on load due to the fact that the trajectory of each ship in orbit would have to be calculated out for run time. Not fun for us or the computer. Oh, and as a side note, we would have to say goodbye to all stable orbits around Kerbin or the Mun. Eventually the other body would perturb all ships into re-entry, an escape trajectory or Mun-splat.

Very nice SasquatchM! That little blimp seems quite efficient! I just completed my latest attempt using this monster: Distance of 2,343,739 m, using C7 basic, hardpoints, experimental and beta gear, Damned Aerospace and MechJeb. Unfortunately my plane suffered an unintentional wing excursion during flight, so I had to set her down.

All the orbits around Kerbin and the Mun would be disrupted by the other body and Kerbol.

50km pitchover is way to high for what you want. Try starting to pitch over very little (~5 degrees) at ~10km, then try and smoothly bring the orientation horizontal by ~50-70km. Definitely use the map view once you start getting above ~20km. Make sure to click the little icon at the bottom of the screen to bring up the navball and give you control in the map view (just remember that you can\'t stage in the map view). And always remember, you can cut the engines and just coast up to apoapsis to circularize the orbit.

A Munar flyby with Periapsis ~2 km. I think their expressions are somewhat appropriate.

Nice job! I\'ve never gotten this ship quite that efficient.

It\'s a celestial body, not a spaceship part. It\'s special.

I personally don\'t like the extra rocket add-ons since the stock parts are crazy-good already, and I really really don\'t like the instant-orbit cheats. On the other hand, C7\'s and Damnyoujapan\'s aerospace parts are wonderful, since it makes exploring Kerbin itself interesting. The space station parts are also nice, since it gives me something to actually put into orbit and rendezvous with. As for autopilots, I happen to like MechJeb for its precision. I like to compare the performance of my rockets, and sometimes two of them are too similar in performance. If I flew manual, human error would be larger than the difference in performance, and I\'d never be able to compare them. It\'s also the best choice if your goal is to use a rocket most efficiently so you can put a massive space station up or to dive the sun using the smallest ship possible. It\'s very good if the goal is to find out what is possible before bashing your skull against the computer trying to do something that just can\'t be done. It\'s also taught me better ascent trajectories (though even MechJeb\'s trajectories need A LOT of work) and as a result allowed me to design smaller, better rockets that are easier to fly--manually or automatically--than the behemoths I used to use. Flying something manual is always the most fun, and I remember landing on the Mun using nothing but a single engine and ASAS for control and trying to land Buck Rodgers style without stranding Bill, Bob and Jeb. The autopilot has its place, but manual is always more satisfying.

You could make it as large as the Mun and still wouldn\'t see it. Parts don\'t render until they\'re about 2.5 km away.

Actually, with v1.8 and the transfer function in the new orbital operations section for MechJeb, it can put you into orbit around the Mun with one click to transfer and another click to circularize. So yes, there is a Mun button.

With the update of MechJeb to v1.8, we now have a built-in delta-V measure for exactly how efficient our ascents are (Yay ascent stats! ). So, let\'s try and do it as efficiently as possible. So using this ship (attached at bottom of post): Insert into a circular 100km orbit using any ascent profile and options you like. You must use MechJeb\'s ascent autopilot to achieve orbit and it must be v1.8 so we have ascent stats, but beyond that, you can do anything else, just post a picture of the ascent stats, the ascent path, the orbital information and tell us what you did, like so: I just put in the shown settings and hit spacebar. Nothing fancy. Minimum delta-V to orbit wins. Happy launching! EDIT: If you decide to take manual control of the ship during ascent, you should say what altitude you took control at and how you piloted it. Videos are preferable, but not mandatory. LEADERBOARD 1. DonLorenzo - 4257 m/s expended 2. grovest4life / UmbralRaptor - 4309 m/s expended 3. togfox - 4313 m/s expended 4. ferram4 - 4322 m/s expended 5. 6. 7. 8. 9. 10.

Is it a Lockheed TriStar? Looks nice.

That\'s actually why I stopped collecting data; no point in collecting obsolete data, though collecting it for the people with the demo might still be helpful if the demo isn\'t retrofitted with the new aerodynamics. I guess we\'ll just have to wait until 0.15 is out and see.

vexx32 is correct, that does help a bit. You may want to try making your landing vehicle wider and squatter to help make it more resistant to tipping in the first place.

The aerodynamic model is currently very primitive and not much has been done. For drag, I would recommend this topic. It is an analysis of the highest altitude with a given rocket launched straight up, and handles drag fairly well. As I recall, the drag formula is: D = 1/2*p*V^2*CD*m, where D is drag p is density (closest I could get to rho ) V is velocity CD is the mass-averaged Maximum Drag of the rocket m is the mass It\'s not the equation for drag in real life, but it\'s what\'s in the game right now. The density equation can be found in the above thread. As for lift, I haven\'t been able to figure out how lift rating scales since I don\'t have the game\'s source code. I do believe that it scales with V^2 like drag, but I don\'t exactly know how. I also know that it scales linearly with the angle of attack (angle between your plane\'s pitch and the direction it\'s going), and found that if you can keep it at about ~25 degrees you get the best lift-to-drag ratio (L/D), and ~20 degrees should get you optimum distance for a plane (trade some efficiency for horizontal velocity). Also, I think the massive wings are the best for L/D, so try using those. If your plane isn\'t gaining altitude and you\'re at an angle of 45 degrees, your plane stalled and you\'ve pitched up way too much and you\'re wasting fuel fighting drag and carrying the weight of the plane (at 45 degrees, half of your thrust is being used to hold up the plane ). Try making your wings larger and get more horizontal velocity. You may want to watch White Owl\'s tutorials. They\'re quite informative. Hope this helps.

Oops. :-[ Close enough for Kerbal Math. Edit: It technically does depend on the radius of the orbit, but that is accounted for in the Vsurface term.

No problem. It also sounds like you do get it, especially if you did have one of those 'Wow, I\'m an idiot' kind of moments (Lovely feeling isn\'t it ). Sorry if I wasn\'t clear earlier, I\'m not very good at explaining math if I don\'t have a notebook to scribble on and show to people.

That is the velocity of the 'surface' of Kerbin, if it came out to the height of your orbit. Using Maraz\'s analogy, that would be the velocity of the tip of the 200km pole relative to fixed space. Your method of simply subtracting the velocity measured on the surface from the velocity in orbit would have worked if Kerbin were flat (), but we have to account for the fact that the surface of Kerbin is moving at 0.1746 km/s on a circle with a radius of 600 km but your ship is moving at 2.101 km/s on a circle with a radius of 800 km. As for this, I actually came up with a formula that should work for doing that, though I haven\'t tried it myself yet: t = (LKSC-LShip)*RK/Vsurf*180/pi LKSC = Longitude KSC, in degrees LShip = Your Longitude, in degrees RK = Kerbin\'s Radius, 600km Vsurf = Your velocity, using the surface number The 180/pi is to convert degrees into radians. The difference in longitudes multiplied by the radius is the arc length of the planet, and your velocity relative to the surface is how quickly you\'re moving relative to that point on the surface.

semininja: It doesn\'t. Your understanding of it is correct, as far as I understand.

Ydoow: Here\'s what a rotating reference frame is: This is a coordinate system located at the center of Earth: Wish I\'d found an animated pic. In the fixed reference frame (the one used for orbital mechanics) the X and Y axes always point in the same direction relative to the entire universe, but not the planet. In a rotating reference frame the coordinate system rotates along with the planet, so that the X and Y directions rotate about the Z axis at the same rate as the Earth spins so that the X direction always points to the same longitude. The former is good for orbital mechanics, the latter for problems on the planet. If you want to have a good idea of what a rotating reference frame is like, imagine standing on a carousel as it spins. You would measure everything off the carousel as moving because you are rotating with the carousel. When the game uses surface velocity, it\'s like you\'re measuring the velocity of things while you\'re on the carousel; when the game uses orbital velocity, it\'s like you\'re measuring the velocity of things while you\'re off the carousel. Hope that helps.

It has to do with the fact that it\'s calculating your speed in a rotating reference frame, not with respect to Kerbin\'s surface. Let\'s back up a bit. Take your velocity on the surface of 0.1746km/s and divide by Kerbin\'s radius of 600km. This will give you a rotation rate of 2.91*10^-4 1/s. Now multiply your orbital radius (not altitude!) by this and you get 0.2328km/s. If you subtract your orbital velocity of 2.101km/s from your 'surface' velocity of 1.868km/s, you get approximately that number. The surface velocity is your velocity with respect to the surface, but instead your velocity in a reference frame rotating with Kerbin.

That\'s a general problem with excessively tall rockets in this game. A picture of your rocket would probably be helpful in figuring out if you\'re doing anything really wrong. As a suggestion, abandon really tall rockets. The way that aerodynamic drag is calculated in the game gives no bonus to skinny rockets over flat pancake rockets (unlike real life) so you might want to try building your rockets squatter first. Actually, even if you want to build tall rockets, making wider rockets is the first step towards fixing your problem: make the base wider and use struts to connect the wider lower stages to the thinner upper stages. Also, I think 1.75m, 2m, and 3m parts aren\'t actually less prone to wobbling than the 1m ones. I think they all have the same amount of flexibility in the joint between the parts.

You want your ap to be greater than the Mun\'s orbit. Keep in mind that you need to be close to it to go into orbit but if you put your apoapsis at the Mun\'s orbital radius you\'ll get smacked by the Mun as it comes around. Aim for about 12,400,000~14,000,000m. This will give you a nice free-return trajectory to Kerbin if you don\'t do anything, and will make sure you don\'t hit the Mun. Make sure that once you get into the Mun\'s sphere of influence you burn retrograde at periapsis to get a nice orbit. For landing, you want to try and kill all of your horizontal velocity and baby it down. Don\'t worry about getting back the first time, just land. You\'ll get a better feel for it with practice. And if you want to come back, make sure you don\'t use a ship that\'s designed to land on its engine. It\'s very easy to lose the engine on landing.