Increasing lift on helicopter rotor blades and airplane propellers
CA 2075752 C · Owner: Krepak, John C. · Inventors: Krepak, John C.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A rotary airscrew having a central hub with coaxial first and second counter-rotating drive shafts a first, set of a plurality of non-lift blades connected to the first drive shaft for rotation to be rotated for moving air therewith, a second set of a plurality of primary airfoil blades connected to the second drive shaft to be, rotated counter to the rotation direction of the plurality of non-lift blades, and spaced apart from the non-lift blades with a small clearance distance to allow non-contacting counter-rotation, and a ring for supporting the first and second sets of blades with a small clearance distance between the ends as they are rotated.
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed August 12, 1992 and granted October 4, 1994. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended August 12, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by August 12, 2014.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.