The fans that power the air through the system are based on a unique hollow core concept with annular fan blades. (Proof of the fan theory and configuration is needed.) Fans would be spaced as necessary to maintain the specified air speed and pressure using reasonably sized motors.

 

50 HP fans could accelerate a pod in the entry ramp plus power up to 60 pods in 1500ft of level tube. A 2 degree up-grade would require 150 HP for 1500ft including 37 pods spaced at 40 feet. That is 4 HP per pod.

 

Redundancy should be provided by having enough spare capacity in each fan unit such that if any one fan unit fails, the remaining units can maintain the minimum system air performance. Failure of an entry-ramp fan would cause the loss of that ramp. References: Propulsion Fan, and Intersection Fan.

 

The fan intake cowling section slices off about 25 % of the upstream air and directs it to the annular fan section. The amount of air drawn in would be equal to the annular space between the 7 feet tube wall and the hollow fan core of 6 feet, or 31,400 CFM.

Fan units that draw air from a second intersecting tube or entry ramp would need to move an additional 120,000 CFM through the intake cowling and fan.

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Outside air inlet vents may also be provided under certain conditions to maintain system air flow and pressure and to provide fresh and cooled air into the tube.

The fan blades are located around this 6 feet diameter annular zone. The fan pressurizes the 31,400 CFM and re-injects the air through the fan outlet duct. The fan flow remains constant with the pressure varying as needed to overcome friction losses and move the pods. The remaining 87,100 CFM of air in the upstream tube is forced through the hollow fan core via momentum along with the pods.

Until system air momentum can be established at start-up, the fan outlets may need to have an annular nozzle to increase the air speed as it is directionally re-injected into the main tube. This will reduce the pressure in the fan core via the venturi effect and induce the upstream air through the fan core and prevent the air from short-circuiting through the fan core. The nozzle could be mechanically operated to open once system momentum is established.

The fan design will need to provide uniform air speed through the main tube and the fan zone to minimize pod turbulence. Under all configurations where the fan must supply or exhaust a second tube or exchange fresh air, the core fan zone must maintain a constant flow.

Excess air from entry ramps and other intersecting tubes are also vented to atmosphere in the fan exhaust cowling to maintain the system air speed and pressure. When the fan supplies an additional 120,000 CFM for an intersecting tube, this added air is injected further down-stream via an extended cowling right into the throat of the intersecting tube. The best configuration for the fan blades and injection nozzle need to be determined to assure forward air momentum is maintained along with the necessary pressure. References: Propulsion Fan, and Intersection Fan.