Brochocki BKB-1
{{Short description|Single-seat Canadian glider, 1959}}
{{Use dmy dates|date=January 2022}}
{{Use Canadian English|date=January 2022}}
| {{Infobox aircraft begin
| name=BKB-1 | image=Brochocki BKB-1 N2991G.jpg | caption=BKB-1 }}{{Infobox aircraft type | type=Experimental glider | national origin=Canada | manufacturer= | designer=Stefan Brochocki | first flight= | introduced=1959 | retired= | status=Sole example destroyed in 1971 | primary user= | more users= | produced= | number built=one | developed from= | variants with their own articles=Kasper Bekas }} |
The Brochocki BKB-1 was a Canadian mid-wing, single-seat, experimental tailless glider that was designed and constructed by Stefan Brochocki with assistance from Witold Kasper and A. Bodek. The designation indicated the contributions of all three men. The aircraft was intended to study flight above the stall angle.{{Cite web|url = http://www.sailplanedirectory.com/PlaneDetails.cfm?PlaneID=37|title = Bekas 1-A Kasper|accessdate = 6 August 2011|last = Activate Media|authorlink = |year = 2006|url-status=dead|archiveurl = https://web.archive.org/web/20120819215958/http://www.sailplanedirectory.com/PlaneDetails.cfm?PlaneID=37|archivedate = 19 August 2012|df = }}Rogers, Bennett: 1974 Sailplane Directory, Soaring Magazine, page 94. Soaring Society of America, August 1974. USPS 499-920
Design and development
The BKB-1 was constructed in 1959 and built entirely from wood. The {{convert|39|ft|m|1|abbr=on}} wing was swept, had a 9.5:1 aspect ratio and employed a NACA 8-H-12 airfoil. The aircraft had a very high wing area of {{convert|160|sqft|m2|abbr=on}} which resulted in a light wing loading of just 3.81 lb/sq ft (18.6 kg/m2).{{Cite web|url = http://www.ae.illinois.edu/m-selig/ads/aircraft.html|title = The Incomplete Guide to Airfoil Usage|accessdate = 1 July 2011|last = Lednicer|first = David|authorlink = |year = 2010|archive-url = https://web.archive.org/web/20100420012244/http://www.ae.illinois.edu/m-selig/ads/aircraft.html|archive-date = 20 April 2010|url-status=dead}}
The prototype BKB-1 was originally registered in Canada as CF-ZDK-X. Later it was moved to the United States, owned by Kasper and registered as N2991G.{{Cite web|url = http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=2991G|title = Make / Model Inquiry Results N2991G|accessdate = 15 August 2011|last = Federal Aviation Administration|authorlink = |date=August 2011}}
As a testbed the aircraft went through several modification states. The modifications included aerodynamic devices to improve aircraft control above the stalling angle. These reduced the stall speed to {{convert|20|mph|km/h|0|abbr=on}} and resulted in a 200 ft/min (1.0 m/s) rate of descent while stalled. This allowed stalled landings with no ground roll. As a result of these and other design changes the aircraft was designated as the BKB-1A, the "A" indicating aerobatics. The aircraft was intended to be fully aerobatic, including tumbling maneuvers.
Kasper had a plan to produce the aircraft and the developmental derivative Kasper Bekas, which mount different wings to a common fuselage, as a single kit, with the choice of wings, but it seems none was actually produced.
Operational history
The sole BKB-1A was destroyed on 6 November 1971 near Arlington, Washington, when a pilot conducted unauthorized aerobatics in the aircraft, subjecting it to an estimated negative 30g during a high-speed inverted descent. The 31-year-old commercial pilot, who had a total of 3000 flying hours and five hours on type, was wearing a parachute, but did not bail out and was killed in the accident. The National Transportation Safety Board cited as cause factors that the pilot misjudged the aircraft's speed and overstressed the airframe to failure.{{Cite web|url = https://www.ntsb.gov/aviationquery/brief.aspx?ev_id=62555&key=0|title = NTSB Identification: SEA72FYE19|accessdate = 6 August 2011|last = National Transportation Safety Board|authorlink = |date=August 2011}}
Variants
Specifications (BKB-1)
{{Aircraft specs
|ref=Soaring The World's Sailplanes:Die Segelflugzeuge der Welt:Les Planeurs du Monde Volume II{{cite book|last=Shenstone|first=B.S.|title=The World's Sailplanes:Die Segelflugzeuge der Welt:Les Planeurs du Monde Volume II|year=1963|publisher=Organisation Scientifique et Technique Internationale du Vol a Voile (OSTIV) and Schweizer Aero-Revue|location=Zurich|pages=34–36|edition=1st|author2=K.G. Wilkinson|language=English, French, German}}
|prime units?=imp
|genhide=
|crew=one
|capacity=
|length m=3
|length ft=
|length in=
|length note=
|span m=
|span ft=39
|span in=
|span note=
|height m=
|height ft=
|height in=
|height note=
|wing area sqm=14.4
|wing area sqft=
|wing area note=
|aspect ratio=10
|airfoil=NACA 8-H-12
|empty weight kg=168
|empty weight lb=
|empty weight note=
|gross weight kg=259
|gross weight lb=
|gross weight note=
|more general=
|perfhide=
|max speed kmh=
|max speed mph=
|max speed kts=
|max speed note=
|cruise speed kmh=
|cruise speed mph=
|cruise speed kts=
|cruise speed note=
|stall speed kmh=56
|stall speed mph=
|stall speed kts=
|stall speed note=
|never exceed speed kmh=162
|never exceed speed mph=
|never exceed speed kts=
|never exceed speed note=
- Rough air speed max: {{convert|162|km/h|mph kn|abbr=on|1}}
- Aerotow speed: {{convert|140|km/h|mph kn|abbr=on|1}}
- Winch launch speed: {{convert|100|km/h|mph kn|abbr=on|1}}
|g limits=+5.33 -2.67 at {{convert|162|km/h|mph kn|abbr=on|1}}
|roll rate=
|glide ratio=30:1 at {{convert|87|km/h|mph kn|abbr=on|1}}
|sink rate ms=0.72
|sink rate ftmin=
|sink rate note= at {{convert|71|km/h|mph kn|abbr=on|1}}
|lift to drag=
|wing loading kg/m2=18
|wing loading lb/sqft=
|wing loading note=
|more performance=
|avionics=
}}
See also
Notes
{{reflist}}
References
{{refbegin}}
- {{cite book|last=Shenstone|first=B.S.|title=The World's Sailplanes:Die Segelflugzeuge der Welt:Les Planeurs du Monde Volume II|year=1963|publisher=Organisation Scientifique et Technique Internationale du Vol a Voile (OSTIV) and Schweizer Aero-Revue|location=Zurich|pages=34–36|edition=1st|author2=K.G. Wilkinson|language=English, French, German}}
- {{Cite web|url = http://www.sailplanedirectory.com/PlaneDetails.cfm?PlaneID=37|title = Bekas 1-A Kasper|accessdate = 6 August 2011|last = Activate Media|authorlink = |year = 2006|url-status=dead|archiveurl = https://web.archive.org/web/20120819215958/http://www.sailplanedirectory.com/PlaneDetails.cfm?PlaneID=37|archivedate = 19 August 2012|df = }}
- {{Cite web|url = http://www.ae.illinois.edu/m-selig/ads/aircraft.html|title = The Incomplete Guide to Airfoil Usage|accessdate = 1 July 2011|last = Lednicer|first = David|authorlink = |year = 2010|archive-url = https://web.archive.org/web/20100420012244/http://www.ae.illinois.edu/m-selig/ads/aircraft.html|archive-date = 20 April 2010|url-status=dead}}
- {{Cite web|url = http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=2991G|title = Make / Model Inquiry Results N2991G|accessdate = 15 August 2011|last = Federal Aviation Administration|authorlink = |date=August 2011}}
- {{Cite web|url = https://www.ntsb.gov/aviationquery/brief.aspx?ev_id=62555&key=0|title = NTSB Identification: SEA72FYE19|accessdate = 6 August 2011|last = National Transportation Safety Board|authorlink = |date=August 2011}}
{{refend}}
Category:1950s Canadian sailplanes