So I made an oxidizer-free cargo SSTO..

[AeroGav]

I've always liked to put NERVs on my spaceplanes,  but nonetheless accepted the received wisdom that their weight more than offsets any fuel saving to be made, especially if you're only going to low orbit.    Imagine my surprise when i built these large, mk3 low orbit transports,  and found i get better payload fraction then the pure chemical ones?

The cargo version made 43.7% payload fraction to 100km and feels like it could go further with extra fuel (the engines and wings can deffo lift more).

Obviously payload fraction isn't that big of a deal.    

Ease of use, part count, even time-to-orbit, are more important considerations.  The "Partridge" (43.7%) is probably a couple of minutes slower to orbit than Thor Wortansen's 35% payload fraction entry, and definitely has a higher part count for a lower payload.   I'd dispute it's at any "ease of use" disadvantage,  the huge wing area (necessary to make NERV-powered flight in upper atmosphere viable) makes for a very docile ship that's easy to take off, land and re-enter.

https://kerbalx.com/AeroGav/partridge

The key design parameters for an oxidizer-free SSTO are very different for a RAPIER-only one, less focus on weight reduction and fuel capacity, more on lift/drag.  Once you get a feel for it, it's not that hard.

Just wish i'd come to this realisation sooner..

pax ship -

https://kerbalx.com/AeroGav/Lusitania

[DerekL1963]

20 minutes ago, AeroGav said:

Ease of use, part count, even time-to-orbit, are more important considerations.

You've discovered a real-world truth, design is a complex balancing act between multiple priorities.

[KerikBalm]

I didn't see any payload or starting mass for that... can't verify 43% payload fraction claim. Also I seem to recall that >50% payload fraction designs have been made which used oxidizer.

[Deddly]

Well done, @AeroGav. Quite an accomplishment.

Moved to Spacecraft Exchange since it seems to belong here .