Medium payload with minimal tech?

[RSwordsman]

I've tried solving this issue by myself many times, but so far have been unsuccessful. For starters, I'm about halfway through the tech tree. While I can bring light payloads to the Mun, Minmus, and beyond with fuel to spare, I just can't seem to lift my most recent project into orbit. It's a fuel module made with the second largest Rockomax tank, plus a few bits and bobs so I can adjust attitude and attach it to my 200km station. However, the lifter that has been my workhorse with smaller modules (basically a tri-coupler with double stacked FL-T800s over LV-T45 engines and some large SRBs on the outside to help it) does not come close to cutting it.

First I tried redesigning the lifter to use the same larger fuel tanks. I stacked two Rockomax 32s together to equal an orange tank (not unlocked), then made a cluster of 6 T45s and a T30 in the center underneath. Then I radially coupled a combination of solid and liquid boosters on the outside, but still I couldn't get it to the desired altitude and orbit.

With that, I'm pretty much out of ideas that don't involve ridiculous concentric circles of asparagus-staged boosters. Does anybody have some good ideas that use only the earlier tech levels, yet still have a respectable TWR and fuel capacity to move a sizeable payload?

*I'll also add that I'm not an engineer or physicist, so my scientific method replaces "research" with "trial and error" in the Kerbal fashion .

Edited December 31, 2013 by RSwordsman

[Sauron]

Hrmm. You don't have the skipper, I assume?

In mid career, the following setup works fairly well for me:

Core: 2 Rockomax 32s, 1 Skipper, 1 Large SAS, Payload

2, 4, or 6 identical copies of the core stage. Asparagus staged (IIRC) 4 boosters plus the core will get a Rockomax 32 and change into a decent orbit.

While I use the skipper to save on part count, there's no particular reason you couldn't use a cluster of LV-T30s instead.

[RSwordsman]

Hrmm. You don't have the skipper, I assume?

In mid career, the following setup works fairly well for me:

Core: 2 Rockomax 32s, 1 Skipper, 1 Large SAS, Payload

2, 4, or 6 identical copies of the core stage. Asparagus staged (IIRC) 4 boosters plus the core will get a Rockomax 32 and change into a decent orbit.

While I use the skipper to save on part count, there's no particular reason you couldn't use a cluster of LV-T30s instead.

You're correct in assuming I don't have the skipper. One more unlock!

I'll try that setup. Maybe I'm still thinking too small. Thanks for the recommendation; will update with results.

EDIT: A cluster just as described with 5 stacks total seems to have done the trick. Ran out of electricity on the first launch so I'm trying again with fixed panels But thanks for the nudge in the right direction.

Edited December 31, 2013 by RSwordsman

[SRV Ron]

Career ship, before Skippers, that will reach Eve and Duna easily.

With the booster ring, Jool and its moons when taking advantage of aerobraking to achieve capture to orbit.

There is still room to add more Delta V with an eight ring booster with four part asparagus. With LV-N unlocked, even more range.

[FREEFALL1984]

I know I'm extremely late in posting this, being that this thread is 8 months old, but in case anyone else should stumble upon it this thread, I solved this same issue just recently by creating a Jet module using the smallest FL-T100 tank, with a standard jet engine attached to the bottom and a single radial intake to the "outside" these can then be retrofitted onto the outside of your lifter by using radial couplers and can sit them as high as you need them to help to balance the whole thing. Each one of these jet modules can easily lift 13 tons on top of its own weight and have more than enough fuel in their own tanks to last 4-5 minutes, a typical 300 ton rocket would need about 24-25 of them to get off the ground. The obvious advantage of this is that you can either get your main rocket up to 10000m before you even need to ignite your main engines or you can simply ignite the whole stack and limit your main engines to 50% in order to boost net ISP. Once you hit the 10k mark its the simple matter of throttling back then waiting a few seconds before staging off the jet engines and hopefully not getting blown up by them as they fly off in all different directions, since they take quite a while to stop once you throttle back, For this reason I tend to hold off on starting my gravity turn until about 12km. But using the first method I can now happily get a 15-20 ton payload into orbit with only 1.25m tech and then still have enough dV to get me to any nearby planet.

[merendel]

Once you hit the 10k mark its the simple matter of throttling back then waiting a few seconds before staging off the jet engines and hopefully not getting blown up by them as they fly off in all different directions, since they take quite a while to stop once you throttle back, For this reason I tend to hold off on starting my gravity turn until about 12km.

Try seting up an action group to kill all the jets at once. Not only can you continue burning full throttle on the rockets but it kills the thrust of the jets instiantly instead of haveing to wait out the spool down time. Action group them off and then stage them and they'll drop like any other spent stage. That said releasing them while they are runing is rather entertaining

[Kryxal]

I usually let them go at full throttle ... it's just that the placement of the radial intakes seems to cause them to peel away safely enough, and of course, there's nothing ABOVE them...

Also, around 10k is where I find the jet engines really START to come into their own, if I use this method I'm probably running them clear up to 20k and building a lot of horizontal velocity!

[kotysoft]

Maybe I'm wrong, but most guys always forget the option to refuel in space... You don't have to carry the whole quantity of fuel you want to use in space. Just enought to dock safely to your Kerbin-orbital station (or simple fuel tank with docking port)... I meant, you can launch (almost) empty tanks, then refuel on orbit.

The less mass you want to launch into orbit, less parts/ kNewtons needed.

At my early progress in carreer mode I always emptied my surplus fuel of homecoming missions into spacestation in LKO.

(you can set fuel/oxidizer amount of a tank in VAB by rightclicking it)

Plus, you need the most efficient engines for space maneuvers, and you can set radially attached engines to custom action group for landing TWR...

Edited March 14, 2014 by kotysoft