Correcting My Rocket - KW Rocketry Installed

[CaptLobster]

Hi everyone. I know (generally speaking) how to fly rockets, and how to build them. However, I don't have a very good imagination (it's pathetic, really) and sometimes I can't decide on which is better; stats on paper or theoretical stats. That might sound confusing to some of you, so let me give an example I frequently have a problem with. I understand that getting into orbit (Kerbin) has "stages." Staying at 150mp/s below 3km, then 300mp/s until 20km, then full throttle. That's the "on paper" stats talking there. However, in my mind, I think igniting your SRB(s) at 100% and your liquid engines (in this case, anyway) at 1/3 thrust sends you very quickly through the atmosphere. Yes, I am fighting the atmosphere going faster than 300mp/s, however I'm also getting out of the atmosphere more quickly allowing myself to be in a vacuum, allowing higher isp for my liquid engines. Anyhow, to the main point.

I built this rocket and would like help on designing it more efficiently. I used it to land on Duna,(had minor changes) and now plan to land on Eve with it. All help is appreciated, so thank you in advance

Here's the rocket file. Was assuming this is how others can see it. Correct me if I'm supposed to do something else, like pictures.

http://s000.tinyupload.com/?file_id=00006957629436093308

[FancyMouse]

Probably fix the ascent profile first? As air is getting less soupy you probably want to do gravity turn fast and build horizontal speed early. 300m/s (if you really mean that) @ 20km sounds you're having too much gravity loss.

[Harry Rhodan]

I understand that getting into orbit (Kerbin) has "stages." Staying at 150mp/s below 3km, then 300mp/s until 20km, then full throttle.

No, that was the old system. Now the terminal velocity is much higher. The rule of thumb is to have a TWR of about 1.5 - 1.7 at launch.

Yes, I am fighting the atmosphere going faster than 300mp/s, however I'm also getting out of the atmosphere more quickly allowing myself to be in a vacuum, allowing higher isp for my liquid engines.

Your gravity losses will always outnumber your atmospheric losses but you still want to get as much horizontal speed as low as possible to make the most of the Oberth effect.

[CaptLobster]

Ah okay. Seems like I had been reading some outdated info lol

I usually never followed that list of steps anyhow, just because to me it always seemed inefficient but it was always in the back of my head. I usually just start my gravity turn at 10km altitude, or higher if my SRBs are still burning.

[Harry Rhodan]

I usually just start my gravity turn at 10km altitude, or higher if my SRBs are still burning.

That is also outdated info. You should start your turn between 50-100m/s. At 10km you should already have turned to around 30° to 45°.

[Streetwind]

Below 300m/s until 20km? Wherever did you learn that kind of thing? That's too slow even with the old aerodynamics, where you actually followed terminal velocity (160m/s at 5km, 250m/s at 10km, 600+m/s at 20km etc). Now in 1.0.4, you can go much faster at lower altitudes without touching terminal velocity. In fact, rockets accelerating with 2.0 to 2.5 G will see terminal velocity running away from them, unable to ever reach it, even though they get reentry effects going up. Which by the way only happens because Squad had to set reentry effects occuring at unrealistically low speeds, or you would never get any from returning from tiny Kerbin's tiny orbit. It is not an indicator for going too fast. The real indicator for going too fast is that you don't tilt over sideways fast enough.

So first things first: go faster. Start with 1.5 TWR off the pad, pitch gently to the side almost immediately, turn off SAS and let gravity pull you into the turn. Reaching 45° somewhere between 10km and 15km is good, but achieving it depends strongly on the TWRs of your launch stage and the timing and intensity of your pitchover, so it may take practice. The first time you stage after passing 20km, you can turn SAS back on and steer manually.

EDIT: Ninjas launched faster than me!

Edited July 6, 2015 by Streetwind

[tomf]

Ive seen staying below 300m/s as a solution to rocket flipping. Staying in the subsonic region until you are out of most of the atmosphere.

[FancyMouse]

Ive seen staying below 300m/s as a solution to rocket flipping. Staying in the subsonic region until you are out of most of the atmosphere.

which IMO isn't a solution at all, at best a workaround - it "solves" the problem by paying too much cost (fuel/dV), where you could have just design the rocket better to really handle supersonic situation.

[CaptLobster]

Read that from a bunch of guides, guess I never checked the date lol...

I've always just started the turn at 8-10km and then kill engines when my apoapsis is at 72km, wait till t-50s then burn (don't know how to give dimensions or coords for navball) east (if i'm saying it wrong, press d lol...) and stay on/behind my apoapsis until my speed raises my periapsis to the same altitude.