So we went over to the pod competition yesterday. I may have some pics later, but some quick observations:
I saw a lot of innovation; as Elon said, of the 27 teams, no two concepts were alike. I was amused that almost everyone had an aeroshell, for a vehicle that’s supposed to operate in vacuum. As I noted to Gwynne (who I just happened to run into for a minute, meeting her husband for the first time), the primary functional purpose of the aeroshells seemed to be to provide real estate for sponsors’ names, like race cars. (I also saw and finally got to meet Sandy Mazza from The Daily Breeze, who has been having fun covering Elon’s antics).
The winners of the race were supposed to be announced at 4:30, but at that point, only the German team had actually run (we heard their pod rattle by behind us as we were eating a hot dog by the tube). Apparently, it took a long time between runs, because they had to evacuate the tunnel after the pod was placed in it, then repressurize to get it out the other end. To pump it down took half an hour. My question (which I didn’t get a chance to ask anyone): Why not have an airlock at each end? Evacuate the tunnel, put the pod in the airlock, evacuate the airlock (which could happen much more quickly, then open the door to the tunnel. Reverse the process at the other end. Seems like it would save a lot of both time and energy.
Finally, as we were walking to the event (we parked at Lowe’s, across the street from SpaceX), we saw a lot of activity in the adjacent SpaceX parking lot. Elon had (as he’s warned on Friday) apparently started digging a hole for his tunnel. As he said in his remarks at the event, they were just getting going, and were going to start trying ideas on better tunneling tech (he thinks it can be improved five or ten fold, in terms of time and cost), but that they didn’t yet “know what they were doing, (which reminds me of an old quote from von Braun, possibly apocryphal, “Research is what I’m doing when I don’t know what I’m doing). Anyway, interesting times in Hawthorne.
At work, I was directed to a photo of the University of Wisconsin-Madison College of Engineering team in the Hyperloop Competition
https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US3707125.pdf
who are making use of the rail guidance system disclosed by V. Milenkovic and G. L. Neidhardt (1972), “Railway Trucks”, U.S. Patent 3,707,125
https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US3707125.pdf
Yes, the Badgers were one of the finalists. In fact, Elon got into their vehicle.
This picture? https://www.engr.wisc.edu/uw-madison-team-hyperloop-competition/
The guy in the back has a rather epic fro.
Are they going to let you have a tour?
C’mon Rand, who cares if they’re traveling in vacuum? You gotta have an aeroshell if you’re going fast.
Unless you’re in space, in which case you need only wings and vacuum inlet ducts.
How else would the engine get enough vacuum energy?
“an aeroshell if you’re going fast”
not even if you’re going fast, even on boats that are ‘performance cruisers’ they’re designed to be sleek but only to 20-25kts!!!
Looks are everything, especially when trying to part people from their money (rich investors for example).
Was the tube transparent or was this more like checking out the boats at a boat show?
It was metal, probably steel. They had cameras inside to track the progress.
Not sure why they’re having this competition, except for engineers to have fun, as I feel the focus is in the wrong area? There’s been maglev for decades; as Rand points out with the aeroshell, it can just be put inside a large soda can shaped vehicle (London Underground train shape-ish) and put into an evacuated tube.
I think the real issues are going to be a) how to maintain such a vacuum in such a large tunnel without expending large amounts of energy, b) what happens when someone puts holes in the tube or vacuum fails (what deceleration forces will be put on people as the train experiences pressure), and c) getting people in/out from vehicle, an airlock type station is needed to be developed unless there’s only one at each end of the tunnel.
How low was the vacuum? As I recall, the initial design involved hovercraft-like levitation with pressures only a couple of orders of magnitude below sea level pressure. Liquid water has a vapor pressure of 4.6 torr at 0 C.
(I suggested in that situation that the residual gas should be mostly water vapor, to reduce the average molecular weight and increase the speed of sound. In that situation, one could flood the tunnel with steam at 1 bar, then cool down with a cold water spray.