Patent US4370097A successfully refreshed from Google Patents.
US4370097A
Expired / Lapsed
US
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Noise reduction means for prop-fan
Assignee: RTX Corp
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Filing: 1979-07-16
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Granted: 1983-01-25
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Expires: 1999-07-16
Abstract
Abstract A prop-fan of the type having a high solidity factor (1 or greater) near the root fairing to a lower solidity factor (less than 1) near the tip and operable over a critical Mach No. range is designed for sound suppression by contouring the tip so that its sweep and sweep distribution of the leading and trailing edge bears a judicious relationship with the Mach surface. This feature is obtainable by designing the planform from a prescribed linearized or non-linearized acoustic theory and tailoring in the sweep so that the leading and trailing edges fall behind the Mach surface.
Inventors
- 👤 Donald B. Hanson
- 👤 Frederick B. Metzger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 22:44
CPC Classifications
B; B64; B64C; B64C11/00; B64C11/16; Y; Y02; Y02T; Y02T50/00; Y02T50/60
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
103 words
A prop-fan having a plurality of rotatable blades supported in a hub for pitch change movement, the airfoil section having a solidity factor of 1 or greater adjacent the root and less than 1 adjacent the tip and operable at a speed where the Mach No. is critical or above critical and the tip speed is transonic or supersonic, said blade having a preascertained sweep distribution which for a given Mach surface for both the trailing and leading edge at a given operating condition said trailing edge is behind the trailing Mach surface and said leading edge is behind said leading Mach surface.
Claim 2
Dependent Claim
103 words
A prop-fan having a plurality of rotatable blades supported in a hub for pitch change movement, the airfoil section having a solidity factor of 1 or greater adjacent the root and less than 1 adjacent the tip and operable at a speed where the Mach No. is critical or above critical and the tip speed is transonic or supersonic, said blade having a preascertained sweep distribution which for a given Mach surface for both the trailing and leading edge at a given operating condition said trailing edge is behind the trailing Mach surface and said leading edge is behind said leading Mach surface.
Claim 3
Dependent Claim
95 words
A prop fan as in claim 1 when said Mach surfaces are obtained from the equation: ##EQU1## where: p T =acoustic pressure r=position where pressure is measured (vector quantity) t=time ∂/∂t=partial derivative with respect to time ∫=integral in the calculus ρ=air density U=blade section relative speed R=is distance between a point on blade and the vector r π=3.14159 . . . h'=slope of thickness distribution of airfoil section γ=chordwise coordinate of blade section M r =section relative Mach number r o =radial coordinate on blade d=differential quantity in the calculus r T =propeller tip radius.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-01-24 | 1986-07-26 | 1987-01-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-01-24 | 1990-07-26 | 1991-01-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-01-24 | 1994-07-26 | 1995-01-25 | $7700.00 | Window Closed / Lapsed |