What's the reasoning behind refunds for parts recovery?

[Zeiss Ikon]

I've played RO in 1.4.1 and 1.6.1, been through the sounding rocket era at least a dozen times before starting over (usually due to either bankruptcy or approaching 1970 without yet so much as a Lunar flyby).

I've never understood why, if you're not using Scrapyard and its companion Oh Scrap!, which handle reuse of recovered parts or assemblies, there's still a refund of parts costs when parts are recovered.  As far as I understand it, reflying used parts was never a thing in rocketry before the Shuttle era.  Yes, there were concepts that intended to treat rockets like airplanes, but even today, most rocketry follows the "artillery" model -- launch it and then sweep up the resulting scrap.

One of the reasons SpaceX is able to offer launch services at prices other companies can't match is that they're the only ones recovering and reusing even a significant fraction of their launch vehicle since the Shuttle was retired (and unlike the Shuttle, they can refly a booster in mere weeks, instead of almost a year).

Yet, even without a mod that lets me reuse recovered parts, if I put (correctly configured) parachutes on my sounding rockets, I get most of the cost of the (significantly more expensive and slower to build) rocket back (even for discarded stages, thanks to Stage Recovery).  This makes no sense.  A WAC Corporal engine has a limited burn time, and the technology of its manufacture would make it cheaper to build a new one than to try to refurbish one to original specifications.  Landing under parachute doesn't generally return a ready-to-fly airframe, either -- flight weight tanks and fins are made of the lightest material that will do the job, and once the tank is depressurized, it'll be prone to buckle under high, off-axis end loads (as with a parachute landing), not to mention the crumpling of the skin where it protrudes past the actual tank domes.  Fins, likewise, are prone to take loads from different directions during landing than what they were built to take in flight, and building them to survive that makes them heavier than they'd otherwise need to be -- which is bad.

So, bottom line: sounding rocket era vehicles can't be practically reflown after recovery, other than possibly the instrument packages.  This is very much true of ICBM-derived launchers, as well -- picture trying to reuse an Atlas balloon tank.  Running the engine until the tank is dry results in loss of the internal pressure that's critical to supporting the tank's own weight, never mind whatever it's supposed to carry as payload or upper stages.  Even if you shut down with, say, 1% propellants remaining, to keep the pressure, there is no way this tank is going to take landing shocks without buckling the tank wall -- picture a full can of beer that gets dropped, and what happens to the cylindrical sides of the can.

The entire vehicle, then, has to be designed for reuse before recovery gains you anything other than data about the flight -- and we get that in the form of the rapidly diminishing "access to a vehicle that survived X" science award after recovery (which, IMO, shouldn't drop off nearly as quickly as it does -- NASA was still learning about reentry in the Shuttle era, learned some after each and every Mercury, Gemini, and Apollo mission, and SpaceX is preparing to learn things no one else has ever known with the thermal management system and swinging fins of Starship).  Until the vessel is actually designed and built in a way that allows reflight, we shouldn't get any kind of refund for the parts.

Edited February 16, 2020 by Zeiss Ikon

[DeadJohn]

13 minutes ago, Zeiss Ikon said:

This makes no sense.

KSP is a game, not a historical simulation. Maybe kerbals build all of their parts with reuse in mind. Or maybe it's just a game mechanic that motivates players to try landing near the space center instead of at random places.