Hi, how can one devise an in flight regenerative braking system for a Jumbo Jet ? How much energy can be recovered and stored when the Jet descends from a cruising velocity of 555 mph at 40,000 feet and comes to rest on the ground at sea level ? Assume the empty weight is 178 tons, its human cargo weighs 45 tons and it carries 50 tons of fuel during the descent.This is a part of my assignment and I'am having difficulty doing it. All I can find on the internet is regenerative braking for auto-mobiles. I would really appreciate if someone could help me with this.Thanks a lot in advance! :)
Presumably, you could recover all the potential energy 200+ tons at 40,000 ft, plus the kinetic energy of the same mass moving at 555 mph. 178+95 = 273 tons 273 x 40,000 = 10.9 million ton-feet.
Probably not practical. The very high peak powers involved would require a lot of heavy generators, inverters, batteries. These would be used only for a minute or two when landing. And the heavy equipment has to be carried for the entire flight, with resulting extra fuel used, plus reduced capacity, which means a few less passengers. The few dollars of electricity recovered would be far outweighed by the (my guess) hundreds if not thousands of dollars lost in fuel costs or passenger revenue. And you would still need the regular brakes as a backup. The above assumes just regenerative braking on the ground. If you want to use some kind of regenerative braking in the air, you would need to replace the flaps with something equivalent that has small propellers running generators. I don't know how practical this is, how you would extend them into the slipstream and retract them when not needed, where they would be stored, and most important, how they affect the aerodynamics of the aircraft. Plus their reliability. Flaps are reliable and have never failed that I know of. .
