OhioBob

How heavy is "heavy"? Since I prefer small payloads, the biggest thing that I've every launched had a lift capacity of 80 t, which is small by many people's standards. I tend to favor simple 2-stage or 2-stage + SRBs designs. My 80 t lifter was just two stages yet, considering its simple design, it had a fairly impressive 0.175 payload fraction. I would have to consider it my best heavy lifter, though I usually use far smaller rockets. I operate under the premise that miniaturization is key to good spacecraft engineering. If I have to build a behemoth rocket to lift my payload, then I consider that a failure in payload design. Below is my 80 t lifter (shown without payload).

If you want a more accurate answer, the burn time can be calculated using the following equation: t = ( mo * Isp * go / F ) * ( 1 - 1 / EXP[ ÃŽâ€v / ( Isp * go ) ] ) where, t = time (s) mo = initial mass (kg) Isp = specific impulse (s) go = standard gravity (9.81 m/s2) F = thrust (N) ÃŽâ€v = change in velocity (m/s)

Think of it this way. When we first start an ascent the orbit is elliptical and suborbital. It is suborbital because the rocket hasn't yet achieved enough velocity to raise it's periapsis above the surface of the Earth. As the rocket ascends and gains horizontal velocity, the periapsis rises. Once the periapsis has risen high enough above the surface that complete orbits can be made without atmospheric drag bringing the rocket back down again, orbit has been achieved. As the rocket continues to gain speed it will push its apoapsis farther and farther away from the planet. When the rocket reaches exactly the escape velocity, the orbit will be parabolic for an infinitesimally small instant. Just as escape velocity is exceeded the orbit becomes hyperbolic. Suborbital and parabolic have nothing to do with each other - you need disassociate those two terms from each other. You should delete your current definition of a parabolic orbit, move it to between elliptical and hyperbolic, a give it a correct description. Furthermore, a hyperbolic orbit has the shape of a hyperbola, it is not parabola-shaped. Hyperbolas and parabolas are two different conic sections. The conic sections and orbital elements are defined here: http://www.braeunig.us/space/orbmech.htm

A good place to start is the following Wiki article: http://wiki.kerbalspaceprogram.com/wiki/Experience'

That's the semi-major axis of an elliptical orbit. A hyperbolic trajectory also has a semi-major axis, though it is a bit more difficult to visualize and understand. In the diagram below the semi-major axis is the line segment labeled "a", which, for a hyperbola, is a negative number.

Perhaps all you need is a diagram... The above is an illustration of a suborbital orbit. The orbit is an ellipse that intersects Earth's surface. It is suborbital because the body crashes into Earth's surface before it can complete an orbit. The part the we can track above ground is a segment of the ellipse.

I agree. At some point I'll likely remove the 'PhysicsSignificance = 1' on all the parts, along with changing/rebalancing some of the part masses. I'm just waiting for Squad to complete their rebalancing before I consider tweaking it further.

I start turning at about 5 km, which is early then what most people seem to do. The reason is to make it a slow gradual turn and to keep the angle of attack small. (The angle of attack is represented by the angular distance between the level indicator and the prograde indicator on the Navball.) This is more efficient than making sudden sharp turns. Consider the following: In figure A a right-angle turn is made using a single sharp 90-degree turn. In figure B the turn is made using two 45 degree turns. In figure C a steady gradual turn is made. In all cases the total ÃŽâ€V provided is 3000 m/s (black). However, you can see that the resultant velocity vector (red) is greatest with a slow steady turn. By starting the turn early and keeping the angle of attack as small as possible, a more efficient turn is possible.

The following page gives all the details and computes the orbital elements: Apollo 11's Translunar Trajectory

True, but I consider that to be an error. The O-10 is the only stock engine that is massless. It is equivalent to the Rockomax 24-77 in size and thrust, yet the 24-77 has mass like all other engines. I always edit the cfg file to change PhysicsSignificance = 0. I do the same thing for the TR-38-D stack decoupler and the FL-A5 adapter. It makes no sense that those parts should be massless; it goes against the apparent intent. I wish Squad would change them. In the meantime there's no reason you can't exploit it.

I think the longest burn that I ever had to do was somewhere in the 5 to 10 minutes range. If longer than that, I do what Red Iron Crown suggested and use more engines. If you have to go with a 60 minute burn, then perhaps you can break it up into a series of shorter burns. Make a maneuver node, burn for 10 minutes and then stop. Create a new maneuver node and burn for another 10 minutes, and so on. You might have to perform your first several burns through successive periapsis passages. Each time you raise your apoapsis higher and higher until the last burn places you on your escape trajectory. It sounds like a real pain to me but it might work. You'd likely have to start the process days before your intended launch window because of the time it will take to cycle through several periapsis passages.

I haven't used MechJeb so I wasn't aware that it does that. Of course computing the ÃŽâ€V of an RCS system is pretty simple to do by hand. Good point. Kerbals do seem to be less concerned with safety than us humans. The Space Shuttle also used bipropellant RCS. I suppose that for large spacecraft like Apollo and the Shuttle, the extra ISP of bipropellant makes it worth the added complexity. Of course these systems used pressure-fed hypergolic propellants, so they were still relatively simple in design. I recall that some of the early plans for Orion called for oxygen/methane RCS, though this was switched to hypergols. The first thing I thought of when I heard that was that it would require some type of igniter. I'm not quite sure how that would have worked for something requiring frequent short pulses like RCS. Presumably the Vernor engine in KSP also requires an igniter.

While what you say is entirely true, compressed gas is sometimes used for RCS. It is usually just referred to as "cold gas". The decomposition of monopropellant is exothermic, meaning that it produces heat. Cold gas is used in applications where the hot gases expelled from a monopropellant thruster could be damaging or dangerous. An obvious example is a manned maneuvering unit. In KSP the Kerbals' EVA packs are said to contain monopropellant, but it's likely that in real life they would use cold gas. Cold gas is far less efficient than monopropellant but it's much safer. The most common and most efficient monopropellant used today is hydrazine, though many early spacecraft used hydrogen peroxide (such as Mercury). In those early days of the space program, engineers hadn't yet found a catalyst that worked with hydrazine without being destroyed during operation. Based on the ISP of monopropellant thrusters in KSP (260 s) it's probably assumed hydrazine. - - - Updated - - - In an application like you show, I often just use point-anywhere RCS ports and angle them aft-ward. They're cheap, massless, and provide plenty of thrust on a small probe. There are three main disadvantages: (1) RCS ports have lower ISP than the O-10 engine [260 vs. 290], (2) you have to hold the H-key down throughout a burn, and (3) you have to calculate the ÃŽâ€V by hand because KER doesn't compute it for RCS.

First time playing career in version 0.90, "Normal" with the standard default settings. When I'm ready to start a new game I'll try something harder.

Probably the smallest launcher that I've used is the following, which completed an "orbit around Minmus" contract. I don't remember ever having a need for anything smaller.

The conical sections are all related to the eccentricity of the orbit. Circular: e = 0 Elliptical: 0 < e < 1 Parabolic: e = 1 Hyberbolic: e > 1 A circular orbit is just a special case of the elliptical orbit. If a spacecraft is traveling at less than escape velocity its orbit will be elliptical. If a spacecraft traveling at exactly escape velocity its orbit is parabolic. And if a spacecraft is traveling faster than escape velocity its orbit is hyperbolic. A suborbital trajectory is actually a elliptical orbit that has its periapsis inside the planet. - - - Updated - - - That's correct, if you assume a gravity vector that is normal to a flat surface, then the trajectory is a parabola. Over short distances this is often a close enough approximation. In the real world, however, the ground is curved and the gravity vector points toward the center of curvature. This makes the trajectory a segment of an ellipse. - - - Updated - - - Thanks for the reference. That's my web page.

I use to call my light, medium and heavy class launch vehicles by the names Dart, Arrow and Javelin. Now I generally just name them LV-XX, where the XX indicates the maximum lift capacity in tonnes to LKO.

0.18.3 (Demo) - Manned orbit of Kerbin; manned orbit of Mun; manned landing on Mun (crashed but survived, no return). 0.23.5 - Purchased July 2014. 0.23.5 - Unmanned landing on Mun; manned landing/return from Mun; unmanned/manned orbit of Minmus; manned landing/return from Minmus; rendezvous/docking; launched/inhabited orbital space station; constructed/inhabited Mun base; operated Mun rover; unmanned landings on Duna & Eve; unmanned landing/return from Duna; unmanned orbit of Jool w/ atmospheric probe. 0.25 - Unmanned orbit of Moho (planned as landing but didn't have enough fuel); launched manned mission to Duna (aborted due to unexplained explosion); launched unmanned probes/landers to Dres, Jool/Bop, and Eeloo (to be completed under 0.90); captured asteroid and placed in Kerbin orbit; performed first aerocapture. 0.90 - Unmanned landings on Dres, Bop & Eeloo (launched under 0.25); rescued crew stranded in solar orbit (from aborted Duna mission); manned landing/return from Duna; unmanned landings on Ike & Gilly.

Why not try unmanned missions first to worked through all the problems before risking your kerbals?

It happened to me once. I don't remember if it was 0.25 or 0.90. It was a situation similar to yours and I have no idea what caused it. It hasn't happened since.

The only thing I've changed so far has been the "PhysicsSignificance" settings on a few parts. There were parts that were massless that I thought should have mass, and some that had mass that I though should be massless. I definitely see some other things that I'd like to rebalance, but I figured I might as well wait for Squad to finish doing their thing before I put too much of my own effort into it. If there are still some things I don't like after version 1.0 is released, then I'll likely start making some additional changes and cloning some new parts.

Squad claims they are interested in making the new system backward compatible such that most old designs will still fly. It's uncertain at this juncture just how that will work.

Also not all depictions of the Frankenstein monster show him with green skin. I believe Mary Shelley's novel described him as having yellowish skin. (ETA) It looks like somebody already beat me to that.

How did you get that number? I've used two methods to calculate the speed of sound and, unfortunately, they yield inconsistent results. The first method uses the given sea level values of density, pressure and temperature. à= 1.2230948554874 kg/m2 P = 101325 Pa T = 293.15 K From ideal gas law the average molecular weight is M = ÃÂRT/P = 1.2230948554874 * 8314.4621 * 293.15 / 101325 = 29.422 kg/kmol where R is the universal gas constant. Given this molecular weight the atmosphere is almost certainly nitrogen-oxygen, giving us a specific heat ratio of 1.40. Therefore the speed of sound is C = (γRT/M)1/2 = (1.40 * 8314.4621 * 293.15 / 29.422)1/2 = 340.56 m/s The second method uses the scale height of the atmosphere, which for Kerbin is 5000 m. Scale height is given by the equation H = RT/(Mg) Therefore, by substitution we get C = (γHg)1/2 Again assuming γ = 1.40, we obtain a speed of sound at sea level of C = (1.40 * 5000 * 9.81)1/2 = 262.05 m/s Clearly the numbers we are given are inconsistent and could not exist together in real life. If we are to believe the sea level values of P, T and ÃÂ, then Kerbin's sea level scale height would have to be 8445 meters. The incompatibility of the numbers we see in KSP makes this really impossible to determine. If we use C = (γRT/M)1/2 and assume a homogenous atmosphere, i.e. M = constant, then we'd expect speed of sound to vary with temperature (as it does on Earth). However, if we use C = (γHg)1/2, and knowing that KSP assumes a constant scale height, then we'd expect the speed of sound to vary with gravity. In the real world everything is internally consistent and these two equations yield the same answer, in KSP, however, they do not.

Based on Kerbin's sea level temperature, pressure and density, and assuming a specific ratio ratio of 1.40, the speed of sound is 340.56 m/s. Since the atmospheric model assumes a constant scale height, the speed of sound is also constant. (I can show the math if anyone is interested.)