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Welcome to the world of engineering practicality.
I think they do need the 100m wheel to expose the problems that a 33m miniature wont be able to expose. As you cited in earlier post, the 33m wheel already costed $38 million, I suspect getting the 100m wheel (and projectile to work) will be many times that. Since centripetal force is proportional to V
2, I suspect their problem list will also grown proportional to V
2. Cost for the final system likely would be somewhere between $38
2 to $38
3: $1.4B to $54B.
Then there is the recurring cost... Even the moving part and the force bearing part will suffer from metal/material fatigue, they will have a limited life expectancy = they are consumables. (According to public TV documentaries) USN Carriers landing catch cable is taken out of service after 100 use.
(An F14 Tomcat is about 40,000 kg empty, about 100x the spin-launch launch vehicle loaded. The deceleration for carrier landing is below 100G, Spin Launch is about 11000G, about 100x a carrier landing. So the magnitudes of the force (=ma) is about the same). I would imagine for safety, the wheel and structure's consumable parts will need rebuilding is around 100 use as well. Rebuilding a by-then known solution is not going to be as expensive as the first-built. But, it could be another few ten(s) of million dollars every 100 launch or less.
This is like my bath room's old plumbing, every time I think about it, the cost got higher.
Honestly, I do hope they will succeed. Beyond space technology, it will be a good achievement for technology and engineering in general. Let's hope they don't solve problems the OceanGate way.