Real SSTO challenge.

[Pds314]

On 7/27/2021 at 9:01 PM, Exoscientist said:

 Keep in mind the main market would be trans Pacific flights that now take a day to make.
Making the flight to space could do it in 30 minutes.

 

  Robert Clark

Yes, but the rocket will be occupied for far longer even under the most optimistic assumptions. It will take minutes to board and deboard, potentially multiple hours to fuel unless that can be dramatically accelerated, and will need safety checks of at least some sort after every flight to make sure it's still spaceworthy.

These things cannot necessarily happen simultaneously either. Checking a rocket for signs of non-spaceworthiness while it's being fueled is not super easy to do, and having the passengers within a kilometer radius while it's being fueled isn't the safest thing either. If you actually have anything that needs to be maintained between flights, you also need to do that. So there will be a lot of people waiting for some stage of this process to complete while other people are waiting on a half hour boat ride after going through security for half an hour. I think you'd be very, very lucky if the flight took under 3 hours from the passenger's POV and that's if everything is timed perfectly. And from the rocket's POV, which, you know, is the actual investment here so any time it's not in flight is not good for business, I think it could be sitting on the pad for 90% of the time if not more during the smoothest of operations. Compared to maybe 10% for a transonic airliner flying intercontinental or ~25% for a supersonic one.

I don't think it's necessarily impossible but you need a rocket that can deboard almost instantly and reboard almost instantly, as well as needing essentially no regular maintainance between flights and being able to fuel in minutes instead of hours. It needs to be both far safer than hitherto existing designs because people do actually factor safety or lack thereof into their travel plans. There needs to be a way for it to land directly onto the pad it will take off from and there needs to be infrastructure to actually get people to the rocket very fast after it's fueled and such, keeping in mind this is likely to be some very large distance. Like 10+ km minimum because, guess what, spaceports both land and sea make bad neighbors. Bad enough that they might even be built in international waters. Which also "solves" the aforementioned regulation issue at least to some extent. However, it would still be well within the EEZ of the host country so it would still be subject to some regulations and couldn't be set up legally by a foreign power.

So your options to get there are basically:
1. Make a boat. Cheap but very slow to go 20 km or so each way. Passengers might just prefer to take an airliner. Might be faster if it's some kind of really fast boat.
2. Make a train. Problematic on water, especially since not transatlantic but transpacific flights would be pretty much the ideal region from an economic standpoint, and giant earthquakes and giant floating or underwater railways don't mix too well.
3. Make a plane. Well... it's fast. You need a landing strip at sea and I question why you don't just fly the whole way, but I guess you could.
4. Put the spaceport on land, but clear a city-sized area around it and then use a train. Not really an option if you want the rocket to land near inhabited areas unless they're landing in a desert or something. But maybe you can fly Salt Lake City to Tashkent? Well, if you land in Kazakhstan and cross the border anyway. Plus, more ways to dodge regulation since those are no longer part of one country since the 90s.

Edited August 12, 2021 by Pds314

[Vanamonde]

Some posts have been removed. The subject of this thread is SSTOs rather than governmental policy. Please stick to that.