I'm having a bad time.

[KerBlam]

This is that Scott Manley video, if anyone is interested.

43 minutes ago, swjr-swis said:

Don't let the fact that someone made a game out of it fool you: it really still is actual rocket science! Buncha fancy-pants astronauts can make it seem easy sometimes, but they too had to work to overcome their instinctive surface-locked motion patterns and thinking, to learn to embrace the Dance of the Orbits and sing the Language of Physics. You have seen the Light!

hehe wow.... I am well versed in the orbits already, that part hasn't changed. The new aero had me stumped though. Completely new way of doing things.

No longer having a bad time, KSP can be fun again XD

[KerBlam]

9 hours ago, rakutenshi said:

Also - does anyone else think we should get a :dv: emoticon that displays "Δv"?

8| how did you type that?

 

[MaxL_1023]

I would use the thrust limiter on the SRBs to get your liftoff TWR to about 1.5, with enough fuel on your center stack to have about 1.25 when your SRBs burn out. If you have the OKTO core (not sure) then forget the Mk I pod - just stick one on top of the Kerbcan to save weight. 

If you need the Mk I pod, try this (from the top down)

Mk 16 Parachute

Mk I Cockpit (attach a couple batteries to the back of it)

Kerbcan

1.25m Heatshield with 100/200 Ablator (should be more than enough)

TR-18A

FTL-400

FTL-400 (If TWR is > 1 with it, otherwise use an FTL-200)

LV-909 Terrier

TR-18A

FTL-400

FTL 400

FTL-400

Swivel (Add FTL-400s until your TWR is at about 1 on liftoff)

Add 4 Hammer SRBs to the sides using radial decouplers. Set the thrust limiter to have a liftoff TWR of 1.25 (since solids increase quickly you set it a bit low). Add/remove fuel to your center stack until it shows a 1.25 TWR when your solids burn out. This 1.25 would be halfway between vacuum and sea level, as you are pretty high up by this point.

Stick some fins on the solids facing radially outwards. If your center stack is more than 4 FTL-400s put the fins on the center stack between the boosters. 

Launch, start a gravity turn at 75 m/s, correct to 45 degrees at 350m/s, then burn prograde. Correct to about 15-20 degrees. When your AP reaches ~55km, burn straight horizontal. Even if you hit AP, you are high enough to escape re-entry heating and can just circularize at your AP of ~80km for a pittance. 

 

It is actually easier to control a rocket with lower TWR in the lower atmosphere, as you climb slower and don't go transonic until the air pressure is ~25% of sea level. Once you make it to about 25km you can control almost anything with thrust vectoring alone - the air is too thin to flip you under most conditions.

Edited January 9, 2016 by MaxL_1023
Added more boosters

[Snark]

17 minutes ago, MaxL_1023 said:

If you need the Mk I pod, try this (from the top down)

<recipe with 2 fuel tanks on the Terrier, 3 fuel tanks on the Swivel, and 4 radial Hammers>

That'll work, but it's overbuilt-- you only need about half as much rocket.  Just one fuel tank on the Terrier, two fuel tanks on the Swivel, and two Hammers will do just fine for a payload of Mk1 pod + kerbcan that's LKO-capable with a reasonable amount of surplus.  (It looks like this.)

[MaxL_1023]

I usually like to have enough delta-V to do random things which can come up, or to do a power-assisted descent. I rarely launch anything with less than 5k delta-v, but that is more a function of the cost-capability curve than anything. It costs almost nothing more for a couple solids and tanks compared to he liquid engines.

[KerBlam]

Alright! After much faffing about and numerous tweaks and spectacular failures I finally got a result I was happy with.

After a near perfect gravity turn, I hardly had to touch the controls it just rolled over beautifully, I got to a 90k LKO with my final  rocket stage mostly intact, I think I had around 1300dV to play with. A lot I know, but I really do like having a bit of a buffer so I'm not squeefing too hard if I blow a burn and have to correct,

Rescued both of the Kerbals without incident.. oh no wait there was an incident. Accidentally lent on the shift key while transferring Jeb back into the cockpit and the damn rescue vessel took off into space. Took a while to get Jeb back in, but I got there.

When everyone was safely stowed away, picked a nice shallow re-entry and dropped in pretty much directly on KSC, which is nice.

So yes I am happily back in the swing of KSP now. Thanks for the help everyone best community ever.

[KerBlam]

Almost forgot. Here is the ship I went with eventually.

[swjr-swis]

13 minutes ago, KerBlam said:

After a near perfect gravity turn, I hardly had to touch the controls it just rolled over beautifully, I got to a 90k LKO with my final  rocket stage mostly intact, I think I had around 1300dV to play with. A lot I know, but I really do like having a bit of a buffer so I'm not squeefing too hard if I blow a burn and have to correct,

Rescued both of the Kerbals without incident.. oh no wait there was an incident. Accidentally lent on the shift key while transferring Jeb back into the cockpit and the damn rescue vessel took off into space. Took a while to get Jeb back in, but I got there.

When everyone was safely stowed away, picked a nice shallow re-entry and dropped in pretty much directly on KSC, which is nice.

So yes I am happily back in the swing of KSP now. Thanks for the help everyone best community ever.

Congratulations, break out the snacks for celebration!

Had to snicker on the rescue vessel taking off accidentally... oh the number of times I touched that Shift at completely the wrong moments.

Awesome and thanks for reporting the success, I enjoyed it.

[Plusck]

Good news! And a nicely aimed return to KSC there too.

 

I hope you don't mind if I mention a couple of related things about staging:

1) Any rocket engine that isn't actually firing is increasing your losses to gravity (as you carry it up, it's just dead weight), and

2) Any rocket engine that isn't at 100% thrust is increasing your losses to gravity (because a lighter rocket would do the job just as well).

Now it obviously isn't possible to respect both rules. Vertically-staged stacks are aero-efficient but break rule 1. And you'd need some sort of script or pages of calculations to get rule 2 right. Also, the obvious exception to rule 1 is where your upper stage has an engine that is inefficient at sea level: you really don't want it to fire until it's reached a decent height.

So with that in mind (and also bearing in mind a sort-of rule 3: the slower your acceleration, the more time you spend fighting gravity) you should really have all available rockets firing at 100% all the way up. With boosters, obviously, this is a problem because they will tend to go too fast in the lower atmosphere, and then they're gone when you need more power later.

The most efficient set-up is therefore to start on maximum throttle on all engines, throttle down as soon as you reach about 200m/s, then throttle back up when you are out of the thickest atmosphere and losing your boosters. I'm currently taking a break from playing so I can't test what KER gives if you move the stages around, but it probably won't be entirely correct since it cannot really determine the order in which you are getting rid of mass (i.e. the boosters) and the fuel that would be left in the main stack at that point.

Edited January 10, 2016 by Plusck

[KerBlam]

11 minutes ago, Plusck said:

1) Any rocket engine that isn't actually firing is increasing your losses to gravity (as you carry it up, it's just dead weight), and

Thanks for the tips. Yeah the staging.. the last stage I always set to not fire instantly when I decouple. Just a personal thing.

Everything is always cranking out 100% Except for the 1st and 2nd stages which thrust output is dialled back to about 85% because SRB's and no throttle control.

[Plusck]

39 minutes ago, KerBlam said:

Thanks for the tips. Yeah the staging.. the last stage I always set to not fire instantly when I decouple. Just a personal thing.

Everything is always cranking out 100% Except for the 1st and 2nd stages which thrust output is dialled back to about 85% because SRB's and no throttle control.

Absolutely, and I agree. I was more suggesting a couple of changes such as firing the LF engine on launch too, then throttling it down, and firing all of the SRBs at launch but dropping the smaller ones as soon as they run out, to tweak even more dv out of the thing. I also tend to dial back SRBs, but I know it is not necessarily a good thing (less SRBs at full thrust should be better in theory, but when they run out the LF engines need to take over earlier and that makes it a difficult balancing act).

Edited January 10, 2016 by Plusck

[Vegetal]

You are finding out the problems of over building, good. For rescue missions I use a rocket that goes to LKO with just 3 flt-400 tanks and no SRBs. Just a single mk1 capsule though, with a probe core. Just to say, you can use very little for good results.

 

[Wemb]

This is a bit late to this conversation, and I wish I had ready access to my #rescue' ship (capable of pulling two lost Kerbals out of LKO) which is built from a two Mk16's on top of each other, and a Stayputnick on the top and some radial parachutes but is still about half the size of your original ship.

One thing I'd add is that if you want to do this slightly more cheaply (and with added thrills for the poor dumb kerbals you're rescuing), try ditching the final decoupler and heat-shield.  If you're in LKO, you should be able to return the Terrier and empty fuel tanks (and kerbals) without needing a heat-shield if you re-entry shallow enough and land sideways onto the water, All that cash does add up in the early game (hence mine designed to return two).

Wemb