{"id":7732,"date":"2013-05-08T11:57:22","date_gmt":"2013-05-08T18:57:22","guid":{"rendered":"http:\/\/cafe.foundation\/blog\/?p=7732"},"modified":"2013-05-08T11:57:22","modified_gmt":"2013-05-08T18:57:22","slug":"avoiding-propeller-strikes-on-electric-aircraft","status":"publish","type":"post","link":"http:\/\/cafe.foundation\/blog\/avoiding-propeller-strikes-on-electric-aircraft\/","title":{"rendered":"Avoiding Propeller Strikes on Electric Aircraft"},"content":{"rendered":"

At last year\u2019s Electric Aircraft Symposium, Ron Gremban, developer of the Prius plug-in hybrid<\/a>, shared several questions about promoting safety in electric aircraft.\u00a0 One aspect that provoked deep thought was that of safety for those working around an electric airplane, whose propeller could start quietly and possibly strike an unaware bystander.\u00a0 During the Green Flight Challenge, it was noteworthy that unlike their gasoline-powered counterparts which idled while awaiting takeoff, the Pipistrel G4 and e-Genius awaited their turn to launch with propellers at rest, only spinning when commanded \u2013 and very quietly at that.<\/p>\n

The question of avoiding prop strikes found at least one answer at EAS VII.\u00a0 Karl Kaser demonstrated, in model form, his ePropeller Safety Device (eSD), noting \u201cthe risk to people, animals or objects in the propeller disk area and that they can be injured or damaged accidentally during the run-up of the propeller.\u201d\u00a0 He first noted that issue in the case of e-Genius, on which he was \u201ccharged with the production management of the e-Genius, first in the workshop shed of the Institute of Aircraft Design of the University of Stuttgart, then at Grob Aircraft in the city of Mindelheim.\u201d\u00a0 He acted as team member and occasional pilot at the Green Flight Challenge.<\/p>\n

e-Genius presented special considerations, with the propeller located above and well behind the pilot and not readily in the field of view.\u00a0 When the electric airplanes were on the ground at the GFC, they can be switched \u201con\u201d with the propeller not moving.\u00a0 Electric motors can also develop enormous torque at even zero RPM, making them potentially lethal even at low speeds when swinging a propeller.<\/p>\n

He referenced the United States Pedestrian Safety Enhancement Act of 2010 and the European Acoustic Vehicle Alerting System as attempts at addressing the problem for ground EVs.\u00a0 Similar approaches applied to aircraft could involve playing a jingle or sound effects to help ground personnel understand the otherwise silent state of the motor.\u00a0 Such an approach might include flashing lights to alert the hearing impaired.<\/p>\n