In re Pappas (185 F.2d 695, 1950)

GARRETT, Chief Judge.

This is an appeal from the decision of the Board of Appeals of the United States Patent Office affirming the rejection by the Primary Examiner, hereinafter referred to simply as the examiner, of the claims embraced in appellants’ application for patent relating, according to the specification, “to airfoils and especially to an airfoil for airplanes characterized by a section or profile which gives greatly increased efficiency at high speeds.” In Webster’s New International Dictionary “airfoil” is defined as “Any surface, fiat or curved, as a wing, aileron, or rudder, designed to obtain reaction upon its surfaces from the air through which it moves.”

No claims were held allowable.

When passed upon by the examiner in his final decision, eight claims-numbered 8 to 14, inclusive, and 19-were involved.. All were rejected by him and all were embrace y that portion of the so-called chord line •OD, extending from O to the perpendicular line CC’ as “extending aft' from the leading edge a distance approximately equalling sixty-five per cent (65%) of the [over-all] length of the chord.” It is thus defined in claims 13, 14, and 19, and was so defined in claim 8.

A feature named in claims 12 and 13 is “a high limiting Mach number.” This is defined in the footnote, supra, as the ratio of the velocity of an airfoil in flight to the speed of sound. In claim 11 “a high limiting Mach number” was specified. It was not present in claims 8 and 9, nor is it found in any other of the claims before us.

Claims 13, 14, and 19 all define a maximum thickness — i. e., a thickness on a line normal to the chord OD (or Ox) of “about eighteen per cent (18%) of the length of the chord.” No percentage factor is designated in claim 10 or 12, nor was any expressed in claim 8, 9, or 11.

Claim 19 embraces all the percentage recitals of claims 12, 13, and 14, and in addition thereto recites that the afterbody [the portion shown between the perpendicular line CC’ to D] extends “over substantially 35% of the chord [OD].”

The board said of the claims now before us that they are more specific to the proportions and dimensions of the profile than claims 9 and 11, and that claim 19 may be taken as illustrative of them.

Omitting, as indicated by asterisks, what the board said of the N.A.C.A. reports, which, as has been stated, we deem merely cumulative, its discussion of claim 19 is as follows:

“* * * This claim specifies that the elliptical forebody of the airfoil section extends approximately 65' per cent of the length of the chord from the leading edge. The patent to Herrick discloses a symmetrical, elliptical body of the basic thickness contour in which the elliptical portion extends aft 100 per cent from the leading edge. Certainly, if a tapering afterbody of the character disclosed in the Mitsubishi and Klemm patents were applied to the Herrick section, the fore-body would extend at least approximately 65 per cent of the length of the chord. However, it is the position of the Primary Examiner that such features as the location of the termination point of the elliptical forebody, the maximum thickness and its location are matters of design and not invention. It is not clear that any surprising results have ensued because of these features.

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“* * * The patent to Taylor clearly directs the movement of the point of maximum thickness aft from the normal position at .35 of the chord in the profile of an airfoil designed for high speeed of the character of that referred to by applicants. It is our view that the prior art suggests every feature of the section defined in the claims and that the claimed section does not depart from the prior art sections to an extent resulting in a difference in kind. The affidavits of record do not establish that the proportions claimed are critical nor that a departure from these proportions has resulted in failure or markedly decreased efficiency of airfoils otherwise constructed in accordance with the claims.”

In previous parts of its decision the board had stated that the patent to Herrick “discloses an airfoil in the form of a wing which has a profile which is derived from a basic thickness distribution contour in the form of an ellipse”; and that the profile section of the wing referred to as “oval” in the Mitsubishi specification may “reasonably be translated as ‘elliptical’.” (It is noted that this is a French patent issued to a Japanese firm, published September 14, 1928.)

The portion alluded to is shown as 2 in Fig. 2 of the patent drawings. To us it seems to be clearly elliptical in shape. We note, however, that the board said: “* * * The patentee does not disclose that the portion 2 is given its form because of any aerodynamic considerations but instead is concerned primarily with the structural features of the wing.”

As to the Klemm patent which the examiner described as being “similar to Mitsubishi,” meaning, we assume, with respect to the elliptical feature, the board said: “* * * [It] discloses an aircraft wing which, when completed, will have a profile consisting of an elliptical fore-body * * * and an afterbody * * tapering aft from the maximum thickness of the contour to a relatively sharp trailing edge. Inspection of the drawing of the Klemm patent does not reveal that the forebody * * * is elliptical and it is described as forming with the member 3 ‘an egg-shaped cross section.’ It is, however, clearly described on page 1, first column, line 21 as ‘elliptical’.”

Continuing the board said: “ * * * If it is found that the Mitsubishi patent or the Klemm patent cannot be reasonably said to disclose an elliptical forebody, we are of the opinion that it would not involve invention to modify the profiles disclosed in these patents to make them truly and mathematically elliptical in view of the Herrick patent. This patent discloses a truly elliptical basic thickness distribution contour * * *, having the chord or major axis * * *„ The airfoil section is derived from this basic distribution contour in exactly the same manner that applicants derive their section from the basic contour, that is, by use of the contour line * * *, which results in the airfoil section shown in full lines on the drawing. This airfoil section is symmetrical in its forward and after portions apparently for the reason that the patentee desired to operate it in either of two opposite directions as in a reversible thrust propeller. It is also apparent that it would involve no invention to provide the airfoil section disclosed in the Herrick patent with the usual sharp trailing edge in view of the Mitsubishi patent, the Klemm patent as well as other references of record.”

Of the feature, “a high limiting Mach number,” named in claims 12 and 13, the board said, in discussing it in connection with its approval of the examiner’s rejection of claim 11: “* * * The quoted phrase might be considered as a functional phrase so that one would expect that an airfoil made with a forward portion and an after portion in accordance with the terms of the claim would, because of these-features, have a high limiting Mach number. If this is the fact, then obviously the airfoil sections disclosed in the prior art patents, such as the patent to Mitsubishi, would also have a high limiting Mach, number. However, the only limitative meaniiig which can be said to be imported into the claim by the quoted phrase is that the airfoil made with the section defined in the claim has a feature which will give it a high limiting Mach number. A Mach number is the quotient of the speed of air and the speed of sound. It is used in compressibility calculations. We have found no definition of the term “limiting Mach number” but the “critical Mach number” is the Mach number at which air attains the speed of sound when flowing past some point on an airplane.”

As we understand the foregoing, it simply means that a high limiting Mach number — “the ratio of the velocity of an airfoil in fight to the speed of sound”— is a result which flows from the arrangement followed in appellants’ structure and that such result would flow from the arrangement of structure in the prior art.

This does not seem to us to be a particularly material limitation in the two claims. We do not understand appellants to contend that it is a critical feature, but, however, this may be, it is not regarded important in view of our conclusion upon the case as a whole.

There are certain affidavits in the record which we have studied with care and found helpful to an understanding of appellants’ device. It is noted that the board said of one of them: “The affidavit of Mulholland is convincing that the design of an airfoil in accordance with the application on appeal, because of the mathematical nature of the outline of its profile, facilitates the calculations involved in developing the airfoil. It may be conceded that calculations of properties of any bodies of the character of airfoils are facilitated if the forms may be defined in mathematical terms but this does not import invention into the claims.”

While we do not rest our conclusion upon the affidavits presented, we have the feeling that they are entitled to more weight in determining the controversy than the tribunals of the Patent Office felt was their due.

In view of our conclusion, based upon the facts found and descriptions recited, we do not deem it necessary to quote, or paraphrase at length, the arguments presented on behalf of appellants.

The claims before us are combination claims in which the individual features that make up the combination are quite distinctly specified. The cited prior art, of course, does not disclose any such combination, nor does it seem to us to suggest such a combination.

So far as individual features are concerned, it is true that Herrick indisputably discloses a perfect geometrical ellipse (it is insisted on appellants’ behalf that his is the only prior art reference “that discloses, describes, or even mentions an ellipse in defining the profile of an airfoil”), but it must be remembered that Herrick’s profile purports to be designed for operation in either direction — that is, for flying either forwardly or backwardly —'(incidentally it is said to be applicable to windmills as well as to airplanes) and has the same thickness of edges. It is not seen how it could be combined with a cusped trailing edge. At any rate, there would seem to be no point in making such a combination, assuming it to be possible.

As already has been indicated herein, an inspection of the Mitsubishi drawing leads us to conclude that its profile, while described as oval is, in fact, an ellipse in the strictly geometrical meaning of that term, but it does not appear in the same structural arrangement, nor is there any satisfactory teaching that its purpose in the patent corresponds to the purpose of the elliptical portion of appellants’ profile.

It seems to be conceded that in order to make the prior art conform to the provision in claim 19 (the only claim in which it appears) of “an afterbody extending over substantially 35% of the chord * * ” material modification of such prior art would be .required.

In nearly all cases where the individual features of combination claims can be met only by modification of individual features found in prior art, difficulty arises in determining whether invention is present. The courts generally have been accustomed to resolve doubt on the question of patentability in favor of applicants. This court has considered that to be a “well established rule.” In re Herchenrider, 117 F.2d 261, 28 C.C.P.A., Patents, 876.

It is our conclusion that the instant case is one in which the rule should be applied, and it is so adjudged.

The appeal is dismissed as to claim 9, and the decision affirming the rejection by the Primary Examiner of claims 10, 12, 13, 14, and 19 is reversed.

Reversed.

The brief on behalf of appellants supplies a list of words used in their application and in the prior art, giving definitions of them “as generally accepted in aerodynamics,” which wo here reproduce as an aid in understanding the claimed invention and the prior art.

Airfoil: is any surface or aircraft component, such as an airplane wing, airleron, rudder, or elevator designed and intended to react with the air through which it moves.

Wing: is a general term applied to an airfoil designed to develop the major part of the lift for the airplane and thereby sustain it in flight.

Profile: is a transverse section through an airfoil and illustrates its configuration, shape or contour.

Leading Edge: is the foremost or forward edge of an airfoil with reference to its direction of movement through the air, i. e., the edge thereof first penetrating and dividing the air for flow over the airfoil surfaces. While a profile literally does not have edges, that portion of the profile coinciding with the leading edge of the airfoil is universally designated as the leading edge.

Trailing Edge: is the rearmost or aft edge of an airfoil with reference to the direction of movement through the air. While an airfoil literally does not have edges, that portion of the profile coinciding with the trailing edge of the airfoil is universally designated the trailing edge.

Chord: is an arbitrary datum line from and by which the ordinates and angles of an airfoil are measured. It is the shortest distance between the leading and trailing edges of the profile and is represented by a straight line between these points.

Camber: is the rise of the curve of the profile of an airfoil from the chord and is usually expressed as the ratio ■of the amount of departure of this curve from the chord of the profile to the length of the chord.

Maximum Thickness: is just what the term implies, viz., the greatest thickness of the profile measured on a line normal to the chord and is usually expressed as a percentage of the chord length.

Thickness Ratio: is primarily the ratio of the maximum thickness of the profile of an airfoil to the length of the chord, and is also used to denote the ratio of the thickness of the profile at any point along the chord to the chord length.

Angle of Attack: is the angle between the chord of the profile of an airfoil and the wind direction relative to the airfoil, or the angle between the chord and the path of movement of the center of gravity of the airplane, both of these angles being the same.

Drag: is the total resistance of the airfoil to the flow of air over its surfaces.

Mach Number: ' is the ratio of the velocity of an airfoil in flight to the speed of sound.

Reynolds Number: is a parameter or constant being a nondimensional coefficient used as a measure of the dynamic similarity of airflows. It is mathematically expressed as:

where RN is Reynolds Number, u (mu) the viscosity of the air, V the velocity of the airfoil through the air, L is the chord length of the profile and p (rho) is the density of the air.

However, once the airfoil and its profile is designed and determined its RN may be calculated. Since all airfoils with the same RN behave similarly with respect -to air flow, a scale model of an airfoil therefore will perform in a wind tunnel the.same as a full size airfoil with the same RN in -flight.