HyperLoopDesign is a resource for Hyperloop engineers, looking at the design challenges and solutions for final designs or sub-systems.

Hyperloop Alpha, August 2013. Elon Musk's original proposed Hyperloop Alpha, which runs in a 2.23m (7ft4") diameter tube, at an absolute pressure of 100 Pa ( 1/1000 atmosphere). It used air bearing skis, with an air compressor to provide air. Acceleration thrust is from linear motors on limited sections of the track. ​

Hyperloop Cheetah Cheetah is a design variation released by Richard Macfarlane in January 2014, with a number of changes to simplify and solve problems. Wheels are used which provide traction. Steam from the cooling system is ejected into the tube, increasing the speed of sound, and reducing aerodynamic drag. The pod is 3 seats wide, and the tube is now 2.6 - 2.8m diameter. The seats are in 3 seating modules which roll out at the station.

Maglev and air bearing skis Hyperloop Alpha originally proposed air ski bearings for levitation. But there may be insufficient airflow in the near-vacuum. See air skis here. The tube in the 2016 Pod Competition has an aluminium plate for maglev, but any plate maglev will suffer high drag. See passive maglev plate here. See Arx Pax here. Maglev using copper coils along the whole route would be the ideal levitation system, except for the extreme expense. See maglev coils here.

Wheels - the simpler and more achieveable option. Elon Musk spoke at the 2016 Pod Competition, and recommended wheels.

Cooling using steam Cooling is very efficient by boiling water, and ejecting the steam into the tube Steam has a higher speed of sound, reducing the Mach no. of the pod, reducing aerodynamic drag and shock waves

Station layouts, airlocks and passenger loading

Hyperloop’s greatest challenge is to provide smooth bump-free travel at high speeds. It is likely that the maximum speed is limited by the achievable accuracy of the tube. A resilient suspension system is important Accuracy of the tube Thermal expansion

The vacuum tube is the heart of Hyperloop. It is by far the biggest expense, and the quality of it affects the experience for the passengers. Variable banking Rails are not the solution

Wheel research and development A considerable budget is available for wheel research, as $billions can be saved in the cost of a simple tube without rails, linear motors etc. R olling road test rig can be used for initial research. Full speed pod testing would need a test track at least 45km long. A CFD study is important to study aerodynamic drag.

Steam in the tube reduces vacuum energy cost Vacuum pumping energy is greatly reduced, because the steam only needs to be pumped to a low-pressure condenser The Natural Steam Vacuum is a very low energy solution for 3kPa pressure Vacuum pumps and initial evacuation. Choosing suitable vacuum pumps, and calculating the energy cost of the initial tube evauation, and airlock pumping

Slow progress so far It is now nearly 6 years since Hyperloop Alpha, and progress has been disappointing. The most important decision has been the choice of levitation:- air skis, maglev or wheels. But designers seem to be attracted to technology which is "new" or "futuristic" rather than a logical and balanced decision of the alternatives. ​ Wheels are the best option for high speeds, metal rims have been used at 1,200 km/h (1997) and pneumatic tires at 1,000 km/h (1970), in speed record cars on unprepared surfaces. In contrast, maglev, with $billions of investment, has only achieved 603 km/h (2015), only slightly faster than a high-speed-rail test train. ​ Hyperloop's initial focus was on air skis, designers taking a year or two to realise that it is impossible to generate enough lift under the skis when the compressor is drawing air from a near-vacuum. ​ Now all the development focus is on maglev. Maglev has been unsuccessful due to the extreme cost of the track, lined with continuous copper coils. After 70 years of research, only one 30km system is in service. A maglev Hyperloop is not likely to be built, due to the high maglev cost added to the cost of the vacuum tube.