Spacecraft Designs?

[MAFman]

So, I haven't even bought the game nor will I be able to for quite some time, but I'm already pretty seriously addicted from YouTube videos I've watched (primarily Scott Manley ) Anyway, I am planning a family of launch vehicles for when I do buy KSP, and I need help.

First, I need "light", "medium", "heavy", and "super-heavy" lifters. What would you say would be a typical mass range for each category?

Second, how would I go about designing the ideal rocket for each class? (TWR's are around 1.5 to 2.5)

Third, I am also planning to have a family of upper stages for interplanetary use, also corresponding to the mass classification system outlined above. I need help designing this as well. Each upper stage has a delta-V of about 3 km/s and an acceleration of 1.5g.

Thanks! (And sorry if this was all the biggest n00b question you've ever seen )

[jaredkzr]

Well designing the rocket is half the fun! It might detract from the experience if you got one of us to show you how to do it! If you really just want to dive into the actual flight experience then I'd head over to the Spacecraft Exchange subforum to pick up some craft files.

[MegaFlop10]

These rockets are pretty good, you can take them as example.

There are also Wikipedia pages about launcher weights and such.

Also try putting together your designs with these parts.

If you can send me your designs I might be able to build the rocket and give you tips and all that.

[UmbralRaptor]

Well, a standard approach is to start with the rocket equation, Kepler's laws, and the Vis-viva equation. The first one for rocket performance, and the second and third help to get a handle on various requirements for orbital maneuvers.

For lifter classes, it ultimately depends on what sorts payloads you want and where you want to put them. I'd also argue that for upper stages, 1.5 g is nice to have but far from necessary once you're in orbit. Or even for the last 500-1000 m/s on getting to orbit.

[Chaos_Klaus]

Why don't you check out the demo? :]

I personally design the lifters based on the payload. When Version 1.0 is out in a few weeks, we will all need to reevaluate our lifter designs anyway, as aerodynamics and engine behaviour changes.

[OhioBob]

First, I need "light", "medium", "heavy", and "super-heavy" lifters. What would you say would be a typical mass range for each category?

I generally classify as "light" any launcher made exclusively of 1.25 m parts. As soon as I start adding 2.5 m parts I classify it as "medium". When I start adding 3.75 m parts it becomes "heavy". I consider "super-heavy" to be launchers that start adding additional 3.75 m parts attached radially.

When you say "typical mass" do you mean the total launch mass or the mass of the payload (i.e. lift capacity). Although there are no precise lines of demarcation, my light launch vehicles generally have lift capacities of 5 tonnes or less; my medium launchers lift between 6 and 30 tonnes, my heavy launchers between 30 and 80 tonnes, and my super-heavy launchers >80 tonnes. In regard to total launch mass, light is approximately <40 tonnes, medium 40-200 tonnes, heavy 200-450 tonnes, and super-heavy >450 tonnes.

[Taki117]

Generally I design the rocket for the payload. I need to lift 20t to LKO, no problem. I need to get it to the Mun? That's a bigger rocket. I've only recently started standardizing my rockets, but if I put up a payload with a rocket, I consider that the Maximum Payload Weight for that rocket and anything lighter than that get's the rocket attached, anything heavier gets a new rocket designed.

[Alshain]

In the past I also designed for the payload. I've been thinking about building standard lifters but I want to make sure they are scalable so if I build a 50t and 100t lifter and my payload is 75t, I can remove pieces rather than waste fuel and part cost.

In any case, I'm not going to do that until I know how the ISP and aerodynamic changes affect them in 1.0. There is just no point right now, it would be a waste of time.

[scarybeard]

I played the Demo for like 3 months before purchasing the game. for basic knowledge, its all you need. In fact, I recommend building there for a while with limited parts available so that you get a grasp of basics before being over-burdened with options in the full sandbox mode.

[juanml82]

I generally classify as "light" any launcher made exclusively of 1.25 m parts. As soon as I start adding 2.5 m parts I classify it as "medium". When I start adding 3.75 m parts it becomes "heavy". I consider "super-heavy" to be launchers that start adding additional 3.75 m parts attached radially.

When you say "typical mass" do you mean the total launch mass or the mass of the payload (i.e. lift capacity). Although there are no precise lines of demarcation, my light launch vehicles generally have lift capacities of 5 tonnes or less; my medium launchers lift between 6 and 30 tonnes, my heavy launchers between 30 and 80 tonnes, and my super-heavy launchers >80 tonnes. In regard to total launch mass, light is approximately <40 tonnes, medium 40-200 tonnes, heavy 200-450 tonnes, and super-heavy >450 tonnes.

I call my 60 tons lifters "medium" lifters. Heavy is anything above 100 tons.

As for the OP, as others said, 1.0 should change parts and the way they react to the atmosphere, so it's likely to change.

My interplanetary transfer stages are typically an orange jumbo tank with four nuclear engines (or the MRS quad nuke at the bottom) radially mounted using girders. That, coupled with assorted docking ports, and everything needed to the ship to act on its own (probe cores, power, rcs)

At this point, I usually keep that as a subassembly and I also keep about three lifters as subassemblies. This way, I just design the payload, check it's weight and decide which is the preset I'll use to put it wherever I want to.

My medium to heavy lifters use the 3.5 meters parts, with a KR-L2 or the quad engine at the center (depending on whether the KR-L2 thrust can handle the load) with the double engine which is also a fuel tank around it in an asparagus configuration - the problem with those is placing SRBs below. Typically, that's a girder holding a structural fuselage and the rockets go below it, but that's rather wobbly. I could change the outer rockets to Mainsails, so I just place the S1 rockets below.