Theoretical delta-v limit for an SSTO?

[Royale37]

Question: If I were to launch an SSTO from the runway at the KSC, would there be a theoretical limit to how much delta-v it could have? I'm talking completely stock, and on the most efficient flight path.

[Gargamel]

No 

A practical limit, yes.    But since we can’t prove there isn’t a better more efficient design than the best design out there, there is no theoretical limit.   

 

As for that practical limit, I can easily see a small second stage of the SSTO having a 10k+ dv using an ion engine.    Couldn’t carry much beyond itself, and wouldn’t go fast, but it could go everywhere.  

[king of nowhere]

On 8/29/2024 at 7:53 PM, Royale37 said:

Question: If I were to launch an SSTO from the runway at the KSC, would there be a theoretical limit to how much delta-v it could have? I'm talking completely stock, and on the most efficient flight path.

you mean, the plane goes on its own and will not discard stages?

I've seen a record of going to laythe, then land back on kerbin, then again on laythe, then again on kerbin, and a third time without refueling. considering extensive gravity assists were used, that translates to about 17000 m/s. Most of that was using air-breathing engines, though. I don't remember if it included ions.

if you can use stages, potentially there is no limit.

[Royale37]

4 hours ago, king of nowhere said:

you mean, the plane goes on its own and will not discard stages?

Correct, no dropping stages.

[Gargamel]

2 hours ago, Royale37 said:

Correct, no dropping stages.

Well, then specify a Single stage spaceplane.      Spaceplane =/= SSTO.    SSTO = Single Stage to Orbit.   A spaceplane might be a type of SSTO, or not.   A vertical launch rocket can easily be a SSTO.   Any SSTO can also have stages that are deployed after reaching orbit.  

[Royale37]

3 hours ago, Gargamel said:

Well, then specify a Single stage spaceplane.      Spaceplane =/= SSTO.    SSTO = Single Stage to Orbit.   A spaceplane might be a type of SSTO, or not.   A vertical launch rocket can easily be a SSTO.   Any SSTO can also have stages that are deployed after reaching orbit.  

Knowing that, is there a limit?

[king of nowhere]

13 hours ago, Royale37 said:

Knowing that, is there a limit?

I told you in my answer. that example was able to make kerbin-laythe and back 3 times without refueling.

[GluttonyReaper]

See the "Maximum Delta-V" section of this page of the wiki:
https://wiki.kerbalspaceprogram.com/wiki/Cheat_sheet

There are theoretical maximums for a single stage, shown in that table for a variety of engines - as also explained, this makes some assumptions (negligible engine mass, no payload) that mean you'll never actually hit those maximums, but you definitely can't exceed them without staging.

Jet engines/wings are much tricker to account for, but ultimately they can only give you a limited amount of dV due to lowering thrust at high velocities. The fastest you can theoretically get is 2100m/s with the RAPIER engine, again according to the wiki, which puts you ~200m/s shy of orbital velocity.

So in theory, and almost certainly theory alone, the highest amount of dV after achieving Kerbin orbit you can get in a single stage is 56900m/s, using RAPIERs to ascend and then just pushing yourself into orbit with Xenon engines. But again, in practice, you aren't getting anywhere near that.

[JeDoesStuff]

On 8/29/2024 at 1:53 PM, Royale37 said:

Question: If I were to launch an SSTO from the runway at the KSC, would there be a theoretical limit to how much delta-v it could have? I'm talking completely stock, and on the most efficient flight path.

The highest Payload fraction I've ever achieved with a conventional SSTO (Regular wings, everything else in a fairing) is close to 70%. In terms of just mass deposited in orbit, this is 82% of the launch mass in orbit. Assuming everything else is ion engine and fuel, you could easily get upwards of 30km/s of delta V, but your twr will be too low to be useful (asides from Gilly).