OhioBob

Kalamazoo

Another mod that I think is essential if you play something like Real Solar System or some of the other scaled up solar systems, Kerbal Joint Reinforcement I tried launching a few rockets in RSS with out it, and they behaved like a wet noodle.

(emphasis mine) That's why I recommend KER as a basic essential. All it does is provide information that should probably already be in the stock game. MechJeb goes to another level beyond the minimum basic essentials. Personally, I haven't try MechJeb yet because I still like piloting my own ships. That's not to say I may someday get tired of it and will welcome automating some maneuvers.

Although I purposely played without any mods for the first several months after buying the game, there are now three mods that I consider must haves: Kerbal Engineer Redux Kerbal Alarm Clock Precise Node All three of these are basic tools that just make playing the game much easier. I really wish all three were stock. Another mod, which I didn't consider a must have only because it's also available as a on-line application, is Transfer Window Planner I've got a few other mods install (SCANsat, Outer Planets Mod, Realistic Atmospheres, Hyperedit, and AeroGUI), but the four listed above are the only ones that I will never again do without.

As long as we're getting really heavy into the math, I might as well add a couple more things to the discussion. First, let me say something about the Isp equation given by Crown, Isp = (F * tb) / (m * go) where tb is the burn time and m is the fuel mass (technically the "propellant mass," which includes both the fuel and the oxidizer). In this case, m is the mass of propellant burned in time tb. In many cases, the variable m is replaced by the mass flow rate, denoted ṁ (pronounced "m dot"), where ṁ is measured in mass units per second. (It is common practice that a dot placed over a variable indicates that it is a rate.) Since ṁ is mass units per 1 second, tb is always equal to 1 s, therefore we can drop tb from the equation. The specific impulse equation is more commonly written as, Isp = F / (ṁ * go) My second point is to elaborate on something I said earlier. I mentioned that Tsiolkovsky’s rocket equation uses effective exhaust gas velocity, so let me explain a little about that. Computing the velocity at which exhaust gases are expelled from a rocket nozzle involves a lot of complex thermodynamics that I don't want to get into. However, the equation used is Ve = SQRT[ (2ϒ/(ϒ-1))*(RTc/M)*(1-(Pe/Pc)(ϒ-1)/ϒ) ] where, Ve = exhaust gas velocity (note, not "effective") ϒ = specific heat ratio R = universal gas constant Tc = combustion chamber temperature M = exhaust gas molecular weight Pe = pressure at nozzle exit Pc = combustion chamber pressure Once we have the exhaust velocity, we compute an engine's thrust from the equation F = ṁVe + (Pe – Pa)*Ae where, F = thrust ṁ = propellant mass flow rate Ve = exhaust gas velocity Pe = pressure at nozzle exit Pa = ambient air pressure Ae = cross-sectional area of nozzle exit As you can see, thrust is broken down into two parts: momentum thrust, ṁVe, and pressure thrust, (Pe–Pa)*Ae. As long as ṁ remains constant, Ve and Pe are also constant. In this case we see that momentum thrust is constant; however, pressure thrust varies as a function of ambient air pressure, Pa. This is why rocket engines have different performance at sea level versus in a vacuum. We can isolate the variable part by writing, F = ṁVe + PeAe – PaAe where we can see that the difference in thrust between vacuum and sea level is simply Ae times the sea level air pressure. The different values for vacuum and sea level Isp are simply computed using the different vacuum and sea level values of F. In Tsiolkovsky’s rocket equation we don't want to use Ve by itself because that would ignore the contribution of pressure thrust. To combine the effects of both momentum and pressure thrust, we define effective exhaust gas velocity, C, where C = Ve + ((Pe – Pa)*Ae) / ṁ This simplifies the thrust equation by reducing it to F = ṁC Substituting ṁC for F in the Isp equation gives Isp = ṁC / (ṁgo) = C/go which we rearrange to give C = Isp*go

Exhaust velocity in the rocket equation is actual the effective exhaust velocity, denoted C, where C = Isp*go In KSP, Isp is obtained from the engine stats visible in the VAB, while go = 9.80665 m/s2.

Well, the instructions in the opening post does say... Back to the game... Altair

I've got an off topic question. How do you post a link to a thread like shown above?

I believe the mod Kopernicus is typically used to make changes like this. Unfortunately I've never used it, so I can explain how to do it. I have no idea now to go about adding an ocean or changing the shorelines, but I can help with the atmospheric changes. I know Kopernicus can do it, but there is also a simpler mod called Bodyloader that can do it. I used Bodyloader in a mod that I developed to changes the planets' atmospheres (Realistic Atmospheres). If it would help, I could easily write a config to use with Bodyloader to change Duna's atmosphere to anything you want.

Last year I wrote essay giving my interpretation of the state of astronomical knowledge that should exist at the start of the game. Kerbal Astronomy 101

Some of us finding engineering stuff fun. That's why some of us are engineers. Let us have our fun the way we want to. Others can have their fun they way they want to.

Yekaterinburg

Edmonton

Arcturus

Overheating on Duna is not a problem. I'd recommend a heat shield to play it safe but, for a typical aerocapture, you won't burn off much ablator. Entry from orbit doesn't need a heat shield at all. I have found that the aerocapture periapsis is pretty sensitive your entry velocity and the ballistic coefficient of your vehicle. If you have a relatively slow intercept with a low ballistic coefficient, you'll probably need a periapsis of about 20 km. If you have a fast intercept with a high ballistic coefficient, you'll probably need a periapsis of about 10 km. If you miss on the periapsis, you may not aerocapture at all or you may not pull out of the atmosphere. I'd recommend at practice run and be prepared to revert/reload if you get it wrong.

Antwerp

Saskatoon

Aldebaron

Aleppo

Eagle Nebula

276 Adelheid

Da Nang

Montgomery

I like a liftoff TWR in the 1.3-1.5 range, but's that's because I like to pack on the fuel tanks and load up an engine with as much weight as it can handle. I believe this gives the best cost per ton of payload. However, I'm sometimes forced into using an engine that delivers a higher TWR than I want because that's all that's available. In that case I launch using the higher TWR (assuming it's not crazy high). I never want to thrust limit or throttle back a liquid fueled engine. There's a big difference between arbitrarily lowering TWR just to hit some number, versus lowering TWR by adding fuel. If you got it, use it. The only time I ever consider throttling back a liquid fueled engine is if I have to for control reasons (for instance, the rocket wants to flip or it won't turn unless I throttle back).

You mentioned a payload of ~60 tons. If that's what you've got, then it's possible to get 5000+ m/s using chemical rockets. A couple days ago I did a test where I slapped together a launcher using three Mammoths (central core + 2 strap-ons) and a Rhino second stage. This could deliver 5300 m/s with a 62t dummy payload. Total launch mass was 606 t. That's one of the biggest rocket that I've ever built and launched. Of course, if the payload is much bigger than that, then I too would consider multiple launches and/or in orbit refueling. The problem with using nukes is that they have a low thrust. If you have a really big payload then you'll either have a very low acceleration, or you'll need a lot of nukes. That's a pretty neat trick considering Minmus' escape velocity is 243 m/s.