MK3 Crew carrier

[foamyesque]

12 minutes ago, Jarin said:

Good info post overall, just wanted to comment on this section. Isn't it still better to do your example multistage rather than just stacking a bunch of tanks on a single engine? I've always done my first career orbit with a sold-fuel kicker to get off the pad, then a second LF stage to orbit. Since recovery is still a major pain at the early tech levels, that minimizes your cost to orbit since you're getting more of your dV from the high cost-efficiency solid fuel at the start.

 

The primary reason to build something that's a SSTO that does not return is to return pieces of it, while the rest of the mission stack proceeds somewhere other than LKO. Get to LKO, jettison your liftoff stack and return it, then go interplanetary on a core stage, for example. This allows you to recover what can be very pricey high-thrust LFO engines.

 

Also, there are bodies in the system where dragging a set of wings to them is worth it: Laythe and Eve, maybe Duna depending. They're pure dead mass during your vacuum manouvering, but they more than pay for themselves during reentry, landing, and general exploration.

 

And while it's true that most of the spaceplane designs that are asked for are SSTO, and most SSTOs that are asked for are spaceplanes, it's still important to specify which you're actually after. This thread could entirely be satisfied with a heavy-launch rocket with recovery shenanigans (I'd use wings, but a heatshield-based approach could work).

 

 

[Mikki]

I am sure if we dump kerbals into two large Mk3 cargobays we can send whole west Kerbin in one shot up.
Or do they take harm without a seatbelt?
Going to investigate this issue. 

[Pecan]

33 minutes ago, Jarin said:

Good info post overall, just wanted to comment on this section. Isn't it still better to do your example multistage rather than just stacking a bunch of tanks on a single engine? I've always done my first career orbit with a sold-fuel kicker to get off the pad, then a second LF stage to orbit. Since recovery is still a major pain at the early tech levels, that minimizes your cost to orbit since you're getting more of your dV from the high cost-efficiency solid fuel at the start.

Given the limited part-choice at tech 1 you pretty much need the pod, parachute, decoupler and swivel; only the number of fuel-tanks is in question.  The swivel, let alone the reliant, have enough thrust to SSTO the whole thing, given 11/12 T100 tanks (12 is better but you can just about squeeze it on 11).  I assume mono tweaked out of the pod, 12 tanks plus swivel for the gimballing (3314m/s dV): 17 parts, 9.2t, 5160 funds.

The question then is how many tanks can the hammer SRB replace, and the answer is 3 (maybe 4).  9 tanks, swivel, decoupler and hammer (3425m/s dV): 16 parts, 11.125t, 5510 funds.  even if you replace 4 tanks (3281m/s dV) the SRB option is still more expensive at 5360 funds.  Plus, of course, it's a lot easier if you don't have to think about staging for your first launches ^^.

[Val]

Similar to @Signo's craft, but lighter and less capable?

4x RAPIERs and 4x Nukes.

Takeoff mass is ~93 t
~1000 m/s dV @ 80 km
Includes 8.4 t 2-Kerbal lander with ~2150 m/s dV 

Still not happy with it's performance. Gonna work some more on it.

[Signo]

@Val - I found your design extremely interesting and inspiring (tbh loved it), so I made an attempt too. An easy one - same craft (EVO design) but with 4 rapiers and 1375 oxidizer on board (10750 LF). Slightly heavier, 122+t at take off. 

It was a lot better than the ram/nuke one but still with room for improvement. I saved 2400+ d/v @ 0.57 TWR.

Next I will simply try to load 650 (or more) extra oxidizer, then I will try to reduce the nukes to 6.

 

[Signo]

I pretty much did all of the above (2750 Ox & 6 nukes) and I ended up saving 3000+ m/s @ 0.4 twr - tough choice, 3000 @ 0.4 or 2500 @ 0.6?

Edited September 10, 2016 by Signo

[Jarin]

14 hours ago, Val said:

Similar to @Signo's craft, but lighter and less capable?

4x RAPIERs and 4x Nukes.

Takeoff mass is ~93 t
~1000 m/s dV @ 80 km
Includes 8.4 t 2-Kerbal lander with ~2150 m/s dV 

Still not happy with it's performance. Gonna work some more on it.

Would love to see what you come up with. Do you plan to post the craft file?

[foamyesque]

Eh, I think some of this is overbuilding. The request was for an LKO crew hauler, so:

 

Lifts off by the first hashmarks. Pitch it up to 45 degrees until ~700m/s, then gradually bring it down to ~15 degrees. Hits 200km x 200km with ~300m/s of dV left, which allows for docking & deorbit manouvering. Put it at 40-45 degrees AoA on the reentry, kick it down into a glide path at ~1.3km/s surface velocity.

 

Craft file: https://www.dropbox.com/s/36mg7vhdoopmnjv/Crew Hauler.craft?dl=0

 

 

 

[Val]

6 hours ago, Jarin said:

Would love to see what you come up with. Do you plan to post the craft file?

I haven't had time to work more on it, but here's the pictured version: SSTO H-1 Signature Mk1

The Ascent Profile is identical to the one used on: SSTO L-2 Dunerider (not useable in 1.1.x due to landing gear.)

[Palaceviking]

S.S.T.O.R.S.T.C.R.T.T.R.W.R.O.S.

Single stage to orbit spaceplane that can return to the runway without refuelling or staging.

Just rolls off the tongue.;-) 

[michal.don]

Four Rapiers. Two wings. Two intakes. Simple RCS system. One docking port.

It's not the most efficient design, nor a sophisticated one. But it's a simple one (40 parts, ~100 000 funds) and it does the job just fine - around 500 delta-V left in a 90 x 90 orbit, with a sloppy flight profile and plenty of LF left for landing maneuvers in case the reentry is not very precise. It could be tweaked to perform even better, but it is fine as it is.

Michal.don

[Pecan]

2 hours ago, Palaceviking said:

S.S.T.O.R.S.T.C.R.T.T.R.W.R.O.S.

Single stage to orbit reusable spaceplane that can return to the runway without refuelling or staging.

Just rolls off the tongue.;-) 

FIFY - hey, you messed-up your own perfectly good abbreviation *grin*.  Thank you for playing (I'm happy as long as people are thinking about the terms they use)