Sikorsky Firefly

{{Short description|All-electric helicopter built for research purposes}}  {{Infobox aircraft | name = Firefly | logo = | logo_size = | image = Sikorsky Firefly.jpg | alt = | caption = Sikorsky Firefly | long_caption = | other_names = | aircraft_type = Light Experimental [[electric aircraft|electric]] [[helicopter]] | aim = | outcome = | related = | national_origin = | manufacturer = [[Sikorsky Aircraft]] | design_group = | designer = | builder = | issuer = | status = Defunct | owners = | primary_user = | more_users = | service = | major_applications = | proposals = | prototypes = | number_built = | construction_number = | civil_registration = | military_serial = | radio_code = | requirement = | aircraft_carried = | flights = | total_hours = | total_distance = | construction_date = | introduction = | retired = | first_flight = | initiated = | in_service = | last_flight = | expected = | developed_from = [[Sikorsky S-300]] | variants = | developed_into = | preservation = | fate = | predecessors = | successors = | concluded = }}

The '''Sikorsky Firefly''' is an [[Electric aircraft|all-electric helicopter]] built for research purposes by [[Sikorsky Aircraft]]. It has been called the world's "first all-electric helicopter".<ref name="sajb">Burgeson, John, [https://www.ctpost.com/news/article/Sikorsky-rolls-out-first-all-electric-helicopter-590195.php "Sikorsky to debut first all-electric helicopter"] {{Webarchive|url=https://web.archive.org/web/20201020041759/https://www.ctpost.com/news/article/Sikorsky-rolls-out-first-all-electric-helicopter-590195.php|date=2020-10-20}}, ''Connecticut Post'' of Bridgeport, Connecticut, July 25, 2010</ref> The Firefly is a modified [[Sikorsky S-300|Sikorsky S-300C]] helicopter with its engine replaced by an [[electric motor]] and two [[Lithium-ion battery|lithium-ion]] battery packs. The helicopter would hold only the pilot and no passengers. Sikorsky reported an operating time of 12 to 15 minutes and a top speed of {{convert|80|kn|km/h mph|abbr=on}}.<ref name=":0">{{Cite web |title=Sikorsky Firefly (technology demonstrator) (defunct) |url=https://evtol.news/sikorsky-firefly/ |access-date=2024-11-27 |website=evtol.news |language=en}}</ref>

It was expected that the helicopter would make its first flight in late 2010 or early 2011.<ref name="sajb" /> For undisclosed reasons, the helicopter was never flown and the project is now defunct.<ref name=":0" />

== History == Sikorsky announced the aircraft at the [[Farnborough International Air Show]] in the [[United Kingdom]] on July 19, 2010, and displayed it for the first time at the [[Experimental Aircraft Association]]'s AirVenture 2010 convention in [[Oshkosh, Wisconsin]], on July 26. Upon the Firefly's announcement, Sikorsky revealed that they had been working on the project for over two years. The cost of the project was never disclosed.<ref name=":0" />

==Development== The Firefly was created by replacing the engine of the S-300C light helicopter, which began production in 1964 as the [[Hughes 300]].<ref>{{Cite web |title=Hughes Model 269/300 helicopter - development history, photos, technical data |url=http://www.aviastar.org/helicopters_eng/mcdonnel-200.php |access-date=2024-11-27 |website=www.aviastar.org}}</ref> The S-300C's [[Lycoming Engines|Lycoming]] {{convert|190|hp|kW|abbr=on}}, 5.9-liter, 4-cylinder gasoline engine was replaced with an electric motor, a new motor mount, and two battery packs located on each side of the pilot. The rotor control, transmission and other systems were left essentially unchanged.<ref name="sajb"/> The project was inspired by observing electric drag cars.<ref name="gtm">Dickinson, Boonsri, [https://www.greentechmedia.com/articles/read/an-all-electric-helicopter-will-it-fly "An All-Electric Helicopter: How Far Will It Fly? Is Project Firefly at Silkorsky Innovations the start of silent flight?"], ''Greentech Media'', August 20, 2010, retrieved May 1, 2018</ref>

Sikorsky Innovations director Chris Van Buiten stated that the development of the Firefly was intended to demonstrate the technology required for vertical electric flight.<ref>{{Cite web |last=Patrascu |first=Daniel |date=2011-01-13 |title=Sikorsky Firefly Electric Helo Nearing Test Flight |url=https://www.autoevolution.com/news/sikorsky-firefly-electric-helo-nearing-test-flight-29596.html |access-date=2024-11-28 |website=autoevolution |language=en}}</ref>

==Electric motor and battery== The high-efficiency electric motor is powered by two 45Ah lithium-ion battery packs, each of which weighs {{convert|585|lb|kg}}.<ref name=gtm/> The battery packs, manufactured by Gaia Power Technologies, have a total of 300 cells and produce about 370 volts.<ref name=sajb/> The electric motor is expected to fly with much less noise, emissions and vibration and require shorter maintenance periods over the life of the aircraft.<ref name=sajb/> The electric motor and controller system weighs {{convert|180|lb|kg|abbr=on}}.<ref name="rwds">Smith, Dale, [http://www.rotorandwing.com/2011/01/12/all-electric-sikorsky-firefly-setting-the-curve/ "All-Electric Sikorsky Firefly: Setting the Curve"] {{Webarchive|url=https://web.archive.org/web/20201103090901/https://www.rotorandwing.com/2011/01/12/all-electric-sikorsky-firefly-setting-the-curve/ |date=2020-11-03 }}, January 12, 2011, Rotor and Wing International, retrieved May 1, 2018</ref> Empty weight is close to the {{convert|2,050|lb|kg|adj=on}} MTOW.<ref name="aino">Dubois, Thierry [https://www.ainonline.com/aviation-news/2011-03-06/electric-firefly-will-feel-conventional-s-300c-says-sikorsky "Electric Firefly will feel like a conventional S-300C, says Sikorsky"], March 6, 2011, AIN Online, retrieved May 1, 2018</ref> The batteries, motor and electronic components are air cooled, and the batteries have 15 minute endurance.<ref name="aino"/>

If the aircraft completely loses power, it can [[Autorotation|auto-rotate]] for a safe landing. The pilot would have plenty of warning if the batteries ran down during flight.<ref name="sajb" />

Eagle Aviation Technologies, LLC, installed the new permanent-magnet electric motor and digital controller from U.S. Hybrid, and the batteries.<ref>News release, [https://web.archive.org/web/20131203011019/http://www.sikorsky.com/About+Sikorsky/News/Press+Details?pressvcmid=989b1cb3a2be9210VgnVCM1000004f62529fRCRD "Sikorsky Introduces "Project Firefly" Electric Helicopter Demonstrator"], July 19, 2010, Sikorsky Aircraft, Internet Archive December 3, 2013, retrieved May 1, 2018</ref>

==See also== {{Portal|Aviation}} * [[AgustaWestland Project Zero]] * [[Hughes TH-55 Osage]] * [[Solution F/Chretien Helicopter]]

==References== {{Reflist}}

==External links== {{commons category|Sikorsky Firefly}} *[https://web.archive.org/web/20160304053057/http://www.sikorsky.com/Pages/Innovation/Technologies/FireflyTechnology.aspx Firefly™ Technology Demonstrator] Firefly Sikorsky corporate page (Internet Archive) *[https://www.youtube.com/watch?v=oD8TfjDMYT0 Sikorsky Firefly: An Electric Helicopter] AvWeb report from Oshkosh EAA AirVenture 2010. Interview with Sikorsky Innovations project manager Jonathan Hartman.

[[Category:2010s United States helicopters]] [[Category:Sikorsky aircraft|Firefly]] [[Category:Electric helicopters]] [[Category:2010s United States experimental aircraft]] [[Category:Single-rotor helicopters]] [[Category:Aircraft with skid landing gear]] [[Category:Unflown aircraft]]