Hoppi-Copter
{{Short description|Backpack helicopter}}
| {{Infobox aircraft begin
|name=Hoppi-Copter |image=Pentecost Backpack Helicopter.JPG |caption= Pentecost HX-1 Hoppi-Copter on display at Pima Air & Space Museum, in Arizona, U.S. }}{{Infobox aircraft type |type= Backpack helicopter |national origin=United States |manufacturer=Hoppi-Copters Inc. |first flight={{circa|1940}} |introduced= |retired= |status= |primary user= |number built= |developed from= |variants with their own articles= }} |
The Hoppi-Copter was a functional backpack helicopter developed by the American company Hoppi-Copters Inc. founded by Horace T. Pentecost in the 1940s.{{Cite web|url = https://www.flightglobal.com/FlightPDFArchive/1948/1948%20-%201726.PDF|title = The Hoppi-Copter|date = October 14, 1948|access-date = January 7, 2016|publisher = Flight}} The original Hoppi-Copter consisted of two contra-rotating rotors on a pole attached to a motorized backpack.{{Citation|title = US2461347 A, Helicopter adapted to be attached to a pilot|url = https://patents.google.com/patent/US2461347|first=Horace T. | last = Pentecost | date = 17 Oct 1945 | access-date = 2016-01-07}} Although it was capable of flight, it was extremely hard to control.
Later prototypes of the Hoppi-Copter included versions with the pilot in a sitting position, and were in effect miniature one-man helicopters of a more conventional design, though retaining the contra-rotating rotors and thus obviating a tail rotor. Despite interest from the British Ministry of Supply in the 102 and 104 models,{{cite book |last1=Bridgman |first1=Leonard |title=Jane's All the World's Aircraft 1949 |date=1949 |publisher=Samson, Low, Marston and Co. Ltd. |location=London |page=234c}} none were adopted commercially.{{Cite web|title = Pentecost HX-1 (Model 100) Hoppi-Copter|url = http://airandspace.si.edu/collections/artifact.cfm?object=nasm_A19520054000|website = Smithsonian National Air and Space Museum|access-date = 2016-01-07}}
Variants
;Pentecost HX-1 Hoppi-Copter (Hoppi-Copter 100): original back-pack version.
;Hoppi-Copter 101: equipped with a seat and landing gear, proved that more development was necessary.{{cite book |last1=Bridgman |first1=Leonard |title=Jane's All the World's Aircraft 1951 |date=1951 |publisher=Samson, Low, Marston and Co. Ltd. |location=London |page=248c}}
;Hoppi-Copter 102: framed, with seat for pilot.
;Hoppi-Copter 103: as the 102, but lighter with a more powerful engine and slightly greater rotor diameter
;Hoppi-Copter 104: as the 103, with even greater rotor diameter
;Hoppi-Copter Firefly
Specifications (Hoppi-Copter 102)
{{Aircraft specs
|ref=Jane's All the World's Aircraft 1948{{cite book |title= Jane's All the World's Aircraft 1948|last= Bridgman |first= Leonard |year=1948|publisher=Sampson, Low, Marston and Co. Ltd|location= London|page=271c }}
|prime units?=imp
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|crew=One
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|empty weight kg=
|empty weight lb=173
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|gross weight lb=363
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|eng1 number=1
|eng1 name=Unknown
|eng1 type= {{convert|750|cm3|cuin|abbr=on}} two stroke flat twin
|eng1 hp=35
|eng1 note= at 4,500 rpm; 9.1:1 reduction gearing to rotors
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|rot number=2
|rot dia ft=16
|rot area sqft=402
|rot area note=total
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|max speed kmh=
|max speed mph=96
|max speed note=all performance figures estimated
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|endurance=1 hr at cruising speed
|ceiling m=
|ceiling ft=12000
|ceiling note=hover
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|disk loading lb/sqft=1.8
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