DCT
6:18-cv-01117
Winglet Technology LLC v. Felker
Key Events
Complaint
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Winglet Technology, LLC (Kansas)
- Defendant: Fort Felker (California)
- Plaintiff’s Counsel: KLENDA AUSTERMAN LLC; ADAMS AND REESE LLP
- Case Identification: 6:18-cv-01117, D. Kan., 04/16/2018
- Venue Allegations: Plaintiff asserts venue is proper in the District of Kansas because a substantial part of the events giving rise to the claim occurred there and Defendant has continuous and systematic contacts with the state, including past business dealings and contractual agreements with the Plaintiff.
- Core Dispute: Plaintiff, a winglet manufacturer, seeks a declaratory judgment that its products do not infringe a patent held by its former business partner and licensor, and that the patent is invalid.
- Technical Context: The lawsuit concerns the specific geometric curvature of aircraft winglets, which are aerodynamic surfaces at the wingtips designed to reduce drag and improve fuel efficiency.
- Key Procedural History: The parties have a complex history, originating with a license agreement for the patent-in-suit, which the Defendant inventor granted to the Plaintiff company he co-founded. A dispute over royalty payments for Plaintiff’s "Sovereign Winglet" product led the Defendant to issue a Notice of Default, prompting this declaratory judgment action. The complaint also notes that the patent’s European counterpart was revoked by the European Patent Office (EPO) Board of Appeal for lacking novelty over prior public use, and highlights specific arguments made during U.S. prosecution to distinguish the invention from prior art.
Case Timeline
| Date | Event |
|---|---|
| 2000-12-11 | ’968 Patent Priority Date |
| 2001-12-05 | European (PCT) Application Filed |
| 2001-12-19 | U.S. Patent Office Action Rejects Claims |
| 2002-04-15 | Inventor Files Response to Office Action |
| 2002-11-26 | ’968 Patent Issued |
| 2003-01-24 | Original Patent License Agreement Executed |
| 2014-09-19 | EPO Board of Appeal Revokes European Patent |
| 2014-10-29 | Defendant Felker Sends Notice of Termination of Original License |
| 2015-11-11 | "Termination Litigation" Filed by Plaintiff |
| 2016-02-15 | Amended Patent License Agreement Executed |
| 2017-10-23 | Defendant Felker Sends Notice of Default Under Amended License |
| 2018-04-16 | Complaint for Declaratory Judgment Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 6,484,968 - Aircraft with Elliptical Winglets
The Invention Explained
- Problem Addressed: The patent addresses "induced drag," a type of drag created by a wing's lifting action that reduces aircraft efficiency ('968 Patent, col. 1:5-8). While aerodynamic theory shows that an elliptical distribution of lift along a flat wing minimizes this drag, applying this principle effectively to three-dimensional winglets presented an ongoing challenge ('968 Patent, col. 1:12-24).
- The Patented Solution: The invention is a winglet that curves continuously upward and outward from the wingtip, with a specific geometry that "at least closely approximates the curvature of a conical section," such as an ellipse, parabola, or hyperbola ('968 Patent, col. 1:8-12). This design purports to create a more ideal, elliptical lift distribution in both the spanwise (horizontal) and vertical directions, thereby minimizing induced drag more effectively than prior art winglets ('968 Patent, col. 3:20-25). The specification describes a preferred embodiment where the curve follows an ellipse whose major axis is perpendicular to the wing and intersects the wing-winglet junction ('968 Patent, Fig. 6; col. 4:51-65).
- Technical Importance: The patent asserts that this continuously curved, conical-section geometry provides a significant performance improvement over prior art winglets, which it characterizes as being "essentially planar" or having only a "brief curved transition section" between the wing and the winglet ('968 Patent, col. 6:49-54).
Key Claims at a Glance
- The complaint identifies independent claims 1 and 5 as central to the dispute (Compl. ¶73).
- Independent Claim 1: The essential elements are:
- An aircraft with a wing and a winglet connected at the wing's outer end.
- The winglet surfaces and edges are continuations of the wing's surfaces and edges.
- The winglet "curves as it extends from its inner end out to its outer end tip."
- The curve has an "increasing radius" as it extends outward.
- The curve is from the group of "a generally elliptical curve, a generally parabolic curve and a generally hyperbolic curve."
- Independent Claim 5: The essential elements are:
- An aircraft with a wing and a winglet connected at the wing's outer end.
- The winglet surfaces and edges are continuations of the wing's surfaces and edges.
- The winglet "follows a generally elliptical curve as it extends from its inner end out to its outer end tip."
- The elliptical curve has a "major axis that extends substantially perpendicular to the wing reference plane" and intersects the wing-winglet junction.
- The complaint seeks a declaratory judgment of non-infringement of all valid claims, implicitly reserving the right to contest dependent claims (Compl. ¶74).
III. The Accused Instrumentality
Product Identification
The complaint names the "Citation X Winglet" and the "Sovereign Winglet" (Compl. ¶45). The present dispute, however, centers on the Sovereign Winglet, which is designed for installation on the Cessna Sovereign Model 680 aircraft (Compl. ¶¶ 45, 47).
Functionality and Market Context
The accused products are winglet designs "optimized to provide superior aerodynamic performance benefits" for specific Cessna jet models (Compl. ¶44). The complaint alleges that Plaintiff has been making royalty payments on the Citation X Winglets since April 2016 and on the Sovereign Winglets since November 2017, the latter under protest (Compl. ¶46, 55). The core of the dispute is Plaintiff's assertion that the Sovereign Winglet's design "does not embody the ’968 Patent," which is the basis for its declaratory judgment action (Compl. ¶48).
IV. Analysis of Infringement Allegations
The complaint seeks a declaratory judgment of non-infringement, alleging that its products do not meet key limitations of the asserted claims. The primary infringement question revolves around whether the accused Sovereign Winglet possesses the specific geometry claimed in the ’968 Patent. The complaint used a figure from the patent's prosecution history to highlight arguments the inventor previously made about the nature of the claimed curvature. The complaint includes a figure from the patent application, Figure 9, which was used during prosecution to illustrate the claimed continuous curvature of the winglet (solid line) in contrast to the allegedly straight section of a prior art winglet (broken line) (Compl. ¶19).
’968 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| wherein said winglet curves as it extends from its inner end out to its outer end tip and said curve has an increasing radius as it extends from the inner end of the winglet out to the outer end tip of the winglet | The complaint alleges that its winglet designs do not incorporate this limitation, pointing to arguments made during prosecution that distinguished the claimed continuous curvature from prior art. | ¶¶ 19-20, 73 | col. 6:31-36 |
| wherein the curve that is followed by the winglet is from the group of curves consisting of a generally elliptical curve, a generally parabolic curve and a generally hyperbolic curve | The complaint states that the Sovereign Winglet design "does not embody the ‘968 Patent" and denies that it uses the "patented elliptical winglet geometry" as alleged by Defendant. | ¶¶ 48, 51, 54, 73 | col. 6:37-44 |
- Identified Points of Contention:
- Scope Questions: A central issue will be the proper construction of the geometric claim terms, particularly in light of the prosecution history. During prosecution, the inventor distinguished the claimed invention from the Gratzer prior art by arguing Gratzer’s winglet had a straight portion, whereas the invention was continuously curved (Compl. ¶¶ 19-21). This raises the question of whether any deviation from a continuous conical-section curve, or the presence of any straight section, places a design outside the scope of the claims.
- Technical Questions: The case presents a direct factual dispute over the geometry of the accused Sovereign Winglet. What evidence will be presented to establish the actual, mathematical shape of the Sovereign Winglet, and does that shape meet the "increasing radius" and "generally elliptical/parabolic/hyperbolic" limitations of the claims?
V. Key Claim Terms for Construction
The Term: "a generally elliptical curve" (and its "parabolic" and "hyperbolic" alternatives)
Context and Importance: This phrase defines the core inventive concept and is the focal point of the infringement dispute. Defendant alleges the Sovereign Winglet uses a "patented elliptical design" (Compl. ¶49), while Plaintiff denies this (Compl. ¶54). The final construction of this term will likely determine the outcome of the infringement analysis.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The use of the word "generally" suggests the curve need not be a perfect mathematical ellipse, allowing for some deviation ('968 Patent, col. 6:42). The inclusion of parabolic and hyperbolic curves in the same group further suggests the claim covers a class of conical-section shapes, not just a strict ellipse ('968 Patent, col. 6:43-44).
- Evidence for a Narrower Interpretation: The specification repeatedly emphasizes the "ideal elliptical shape" as the preferred form and provides specific definitions tied to geometric axes ('968 Patent, col. 3:22; col. 5:36-39). More significantly, arguments made during prosecution distinguishing the invention's "continuous" curvature from prior art may be used to argue for a narrower scope that excludes winglets with any substantial non-conical or straight sections (Compl. ¶¶ 19-21).
The Term: "inner end"
Context and Importance: Plaintiff expressly challenges the patent's validity under 35 U.S.C. § 112 for indefiniteness, specifically citing the term "inner end" (Compl. ¶65). The location of the "inner end" serves as the starting point for measuring the claimed curvature, so any ambiguity in its definition could render the entire claim indefinite. Practitioners may focus on this term because its alleged ambiguity forms a basis for Plaintiff’s invalidity defense.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The figures depict a smooth, blended transition between the wing and winglet, which could support an argument that the "inner end" refers to a transitional region rather than a mathematically precise line ('968 Patent, Fig. 6).
- Evidence for a Narrower Interpretation: The specification refers to the wing-winglet junction as "intersection 204" and states that the major axis of the preferred elliptical curve "coincide[s] with the intersection 204," suggesting a more definite location ('968 Patent, col. 4:53-56). Plaintiff will likely argue this description is insufficient to inform one of ordinary skill where the wing ends and the winglet's "inner end" begins with reasonable certainty.
VI. Other Allegations
- Indirect Infringement: As part of its request for a declaratory judgment of non-infringement, the complaint makes a blanket denial of all forms of infringement, including direct, indirect, contributory, and by inducement (Compl. ¶72). It does not, however, provide specific facts relating to these allegations.
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of definitional scope and prosecution history estoppel: How broadly can the term "generally elliptical curve" be construed, and to what extent did the inventor's arguments to distinguish prior art during prosecution limit that scope? The case may turn on whether the inventor disclaimed winglet designs with any straight sections, as Plaintiff appears to suggest.
- A key evidentiary question will be one of factual characterization: Beyond legal definitions, the dispute will require a technical, evidence-based comparison. What is the actual, measurable geometry of the accused Sovereign Winglet, and does it functionally and structurally fall within the scope of the claim limitations as construed by the court?
- A third major issue will be validity in light of foreign proceedings: Plaintiff has put the patent’s validity at issue, pointing to the revocation of its European counterpart by the EPO for lacking novelty over prior use. A central question will be whether the evidence and legal reasoning that invalidated the patent in Europe can be successfully adapted to meet the standards for anticipation or obviousness under U.S. patent law.