What is a simple rocket?

[JackBush]

I keep reading that the best kind of ship to build (at least for a total beginner such as myself) is a simple one. "Keep it simple." I read over and over again. But what constitutes "simple". Would someone mind describing that for me? Thanks so much. (I'm in the demo version.)

Edited August 23, 2015 by JackBush

[Streetwind]

Give me a moment while I look up which parts are available in the demo version.

EDIT:

Okay, urk. Demo rockets are quite tricky. Why? Because 1.) there are no upper stage engines; 2.) there are no engines with thrust vectoring; 3.) there are no control surfaces; and 4.) the one set of guide fins that is present is way oversized for starter rockets.

But nevertheless, I made you a sample rocket. The key design philosophy for simple rockets is "pointy, long, gradual shape; heavy bits at the front, draggy bits at the back". Exactly like an arrow is structured. We're going to skip the fins, though, because the only fins the demo has are way too big and make the rocket all but uncontrollable in the lower atmosphere.

Start with a mk1 pod. Put a parachute on top and a 1.25m headshield below, then a TR-18A decoupler below the heatshield. Then go further downwards:

2x FL-T200 fuel tank

1x Reliant engine (rightclick it and set the thrust limiter to ~30%)

1x TR-18A decoupler

8x FL-T200 fuel tank

1x Reliant engine

This simple rocket, when flown well, gets into orbit with around a quarter of the upper stage's fuel left, which is plenty of margin for practice. It's resistant to flipping out of control due to its long, thin profile. The pod can also safely reenter and land.

Edited August 21, 2015 by Streetwind

[Scarecrow88]

I guess 'simple' means only using what is absolutely necessary to get the job done, whatever the job happens to be. No need to build a 150 parts, 200 ton monster if all you need is a rocket to reach 10,000m altitude, when a 3 part 2 ton craft will suffice.

[GoSlash27]

"Simple" would be a payload, guidance, engine, and fuel tanks (probably some passive fins to keep it stable)

The idea is to get used to the mechanics and math before you start trying to pull off complicated beasts.

Best,

-Slashy

[cantab]

Simple starts at the payload. An extra ton on the payload means an extra ten tons on the launcher, so take only what you need. In the demo you'll probably only be taking a 1-Kerbal pod with a parachute and maybe a couple of Mystery Goos anyway.

It continues with the launcher. Simple generally means a small number of stages - three at most for getting to Kerbin orbit - and little or no use of fuel lines. Simple launchers are also typically "rocket shaped".

My light launchers have tended to follow the following general design:

Payload up top.

Core using a T45 engine, providing most of the delta-V to reach orbit but lacking enough thrust. Small fins on the bottom of the core help stability. In the demo you'll need to use a T30 and maybe add reaction wheels.

Pair of solid boosters on radial decouplers on the core, thrust limited appropriately.

The launch is done at less than full throttle with all engines igniting. After the boosters drop I go to full throttle, and the core has already burned off some fuel so it has enough TWR.

[JackBush]

Thanks folks; appreciate the guidance. Thanks especially Streetwind for the very specific help--exactly what I was hoping for. It's also good to get your readout on what the Demo version "lacks" and, perhaps, why I'm having such great failures. Looking forward to learning from what you've provided me.

[cantab]

Yeah. Expect rockets in the demo to be harder to control and more wobbly than they should be, because of the short fuel tanks and lack of engine options.

[DancesWithSquirrels]

Really simple rocket:

1X Parachute

1X Small inline reaction wheel (since the demo lacks controllable fins, and RCS is more complex)

1X Mk1 pod

1X TR-18 decoupler

9X FL-200

4X AV-T1 winglet

1X Reliant

At about 50 m/s tip ~5 degrees east for the gravity turn, and turn off SAS - you should be ~45 degrees at 10k, and can burn at apoapsis for a 75x75 orbit - leaving more than 50-60 units of fuel to spare, enough to reenter.

Note - once you decouple from the rest of the rocket on reentry you might want to right-click the inline wheel and disable it - with just the pod mass and both pod and reaction wheel running SAS will just oscillate.

Edited August 21, 2015 by DancesWithSquirrels

[Pecan]

Here -> http://forum.kerbalspaceprogram.com/threads/130790-How-can-I-orbit-kerbin-and-the-moon-in-Demo?p=2125733&viewfull=1#post2125733

is a demo version rocket capable of landing on either moon and returning.

For longer, more general, 'start small' designs and missions you might like to look at http://forum.kerbalspaceprogram.com/threads/79658-Exploring-The-System-A-design-tutorial-campaign-0-90-Final

although the ships there are outdated and, in any case, not compatible with the demo version.

As the others have said, the basic idea is not to try too much too soon, and generally try to see how far you can go with the absolute minimum parts, size and mass (not that there's much choice in demo!)

The usual thing people do is keep adding more (everything) to their rockets in an attempt to 'just' reach orbit, when what you really want to be doing is looking at getting rid of bits that aren't really helping.

Set yourself simple goals at first and advance in small steps - get to space (straight up and down again), start working on a gravity turn (and find out why!), reach orbit (it's quite a milestone, which is why 'just' is in inverted commas above), fly-by Mun, orbit Mun, orbit and land on Minmus (the other moon, it's easier although it's further), land on and return from Mun (once you've got this far the hardest part is finding somewhere flat enough to land without tipping over), try rendezcousing and docking with two ships.

[AlextheBodacious]

redstone: chute

MK 1

TR 18A

Long 1.25

reliant