SSTO? 3 stage reusable? 3 stage to 2 orbits? What would you call this

[KerikBalm]

So, in my adventures playing with scaled up systems and the resulting low payload fractions of SSTOs, I started playing with re-usable 2 stage to orbit craft (a suborbital "carrier" and an "orbiter" that reaches orbit fast enough to switch back to the carrier before it falls too deep into the atmosphere.

In such a setting, "go anywhere" craft are a bit out of the question, as you leave a large portion of your craft behind (even if it is reusable). My carrier craft have all the airbreathers, but those air breathers are all rapiers that go into closed cycle to boost the Ap higher and get the orbiter even closer to orbital speed.

So it occurred to me... the unloaded carrier craft may be able to achieve orbit on its own with no orbiter. So, I started working on a new mission profile:

Carrier goes suborbital, orbiter gets to orbit with good fuel reserves. Carrier lands, refuels, and goes back to orbit with basically no fuel left. Orbiter and carrier rendezvous.

In this case, I get the entire craft to orbit (like an SSTO), but its more like 3 stages, and 2 things get to orbit.

When the orbiter is carrying a detachable payload... this can be carried even further. 2 stage to orbit: decouple payload (Staging event?). Land orbiter and carrier.

2 stage to orbit again, Orbiter (with more fuel) redocks with payload, carrier lands and refuels.

Carrier SSTOs, and redocks with orbiter plus payload. If the payload is a fuel tank, this can give the entire setup a substantial dV margin. What would you even 

Perhaps a reusable craft to anywhere can be done in 3x with stock parts? (granted, it won't be coming back from Eve).

 

Has anyone done mission profiles like this? or is it simply too much work to go to orbit, leave as much up there as you can, come back down, refuel, then go up again?

[Streetwind]

I'd say you're conflating flight profile, mission profile, and launch vehicle architecture.

A spacercraft is capable of a single stage to orbit flight profile if it detaches nothing on the way up. Your orbiter does not qualify, as it detaches the carrier. The carrier technically qualifies, but that qualification is pointless, as it carries no useful payload - not even excess fuel. Still, a launch is a launch, I guess...

Therefore, your flight profile is "single stage to orbit" when it's just the carrier, "two stages to orbit" when the orbiter is involved, or even "three stages to orbit" if you detach a payload that inserts into orbit itself. The docked spacecraft in orbit qualifies for none of these, as it was assembled over multiple launches; this is a "low Kerbin orbit rendezvous" mission profile. Meanwhile, your launch vehicle architecture is "fully reusable two-stage vehicle".

EDITed to fix a logical hangup that I only noticed after posting.

 

Edited June 17, 2020 by Streetwind

[theJesuit]

I agree with @Streetwind.

But I like the idea of this setup as i limit the size of rockets by only ever upgrading to tier 2 launchpad and runway.

Howevet the carrier and orbiter together, once the carrier has refueled, returned to orbit and docked... what kind of delta-vee do they have?

Think of a real world scenario...

A Starship and Super Heavy launch.  Starship is reaches orbit.  The Super Heavy lands, refuels, and launches again with no payload, but is able to achieve orbit and redock with the Starship?

[EveMaster]

On 6/17/2020 at 11:42 AM, KerikBalm said:

Perhaps a reusable craft to anywhere can be done in 3x with stock parts? (granted, it won't be coming back from Eve).

 

Has anyone done mission profiles like this? or is it simply too much work to go to orbit, leave as much up there as you can, come back down, refuel, then go up again?

I have done mission profiles like this. I think 'reusable' describes this concept best. I know of no special terms such as SSTO. I also like spacecraft that are completly reusable.

With two stages I managed to do a grand tour while leaving a stage on Eve. In total I used 4 stages on the grand tour mission and 5 stages on the 100 Kerbals to Eve mission getting all stages back to Kerbin even all the Eve stages. The extra stages are because I did not intially plan to recover the grand tour lower stage from Eve and because I had to launch an additional adapter for the 100 Kerbals mission due to a design mistake. But in principle these two missions could be performed with three stages. The trick with Eve was to launch from the highest point and to do a suborbital catching maneuver. Without that it is just barely possible to do an SSTO on Eve.