COMMISSIONER'S DECISION
Sec. 2, 28(3): DETERMINATION OF GROSS THRUST
Measuring engine pressures in a static sea level facility and then calculating a
correction factor for use under old operating conditions is statutory. It is an
improved version over the applicants Canadian Patent which was copending at the
lime of filing.
Final Action - Reversed
******************
Patent application 150,685 (Cl. 354-24), was filed on August 31, 1972 for
an invention entitled Determination of Gross Thrust-Related Parameters.
The inventors are George B. McDonald et al. The Examiner in charge of
the application took a Final Action on April 17, 1978 refusing to allow
it to proceed to patent. In reviewing the rejection, the Patent Appeal
Board held a Hearing, at which the Applicant was represented by Mr. A.
Davidson. Also in attendance was one of the inventors, Mr. G.B. Mackintosh.
The application is directed to a thrustmeter for a jet engined aircraft
which provides an output indicating engine performance at various throttle
settings. The idea is to measure engine pressures in a static sea level
facility, and then derive a correction factor for use under all operating
conditions. Figure 2, below, is representative of that arrangement:
In the Final Action the Examiner refused the claims for failure to define
patentable matter under Section 2 and 28(3) of the Patent Act.
At the Hearing Mr. Davidson stated that the applicant was no longer interest-
ed in pursuing claims 1 to 13 on file and wished to replace them with a
single claim which he presented for consideration. It reads as follows:
Apparatus for determining a correction factor for use in testing
a jet engine of known configuration comprising:
a test stand,
means for measuring gross thrust exerted by the engine on the
stand,
first pressure transducer means positioned to measure nozzle
entry static pressure, the reading being subject to error due
to distortions in gas flow,
second pressure transducer means positioned to measure flame
holder static pressure,
third pressure transducer means positioned to measure diffuser
static pressure,
fourth pressure transducer means positioned to measure ambient
static pressure,
means responsive to the gross thrust measurement and said second,
third and fourth transducer means for determining a corrected value
of said nozzle entry static pressure,
means comparing said corrected value and the measured value at
said first pressure transducer to obtain said correction factor.
The question before the Board is whether or not the proposed claim is direct-
ed to subject matter which complies with the requirements of Section 2 and
Section 28(3) of the Patent Act.
The disclosure outlines the disadvantages oœ the prior art systems, describes
the applicants arrangement and promises improved results. We note that the
disclosure refers to the applicant's copending application 126,454 entitled
"Method and Apparatus for Determining the Thrust of A Jet Engine" now issued to
C.P. 998,770.
Page 10 of the disclosure states that the thrustmeter does not require the
use of an immersed total probe in the nozzle region, thereby making it similar
in that respect to the arrangement found in C.P. 998770. It adds "However,
in the prior art, including the aforementioned application Serial No. 126,454,
it was necessary to provide a gross thrust coefficient C f g to account for
some of the difference resulting from the actual gas flow being different
from a one-dimensional model. The calculation of C f g is elaborate and
requires an altitude test cell to produce the desired nozzle pressure ratios."
At the bottom of page 11 it states:
Accordingly the present invention is based on a discovery
that certain internal engine pressures can be used to provide
a corrected nozzle inlet static pressure which when intro-
duced into the appropriate gross thrust equation will provide
an extremely accurate indication of gross thrust for all
throttle settings regardless of flight mach number and
altitude."
As we understand the disclosure this application describes a thrustmeter
which is an improved version of the one described in the above mentioned
application, now CP 998770. We find that the presented claim defines an
apparatus comprising a number of component elements for determining a correct-
ion factor far use in testing a jet engine of known configuration. We have
no objection to this claim with respect to Section 2 and Section 28(3) of
the Patent Act.
We informed the agent by telephone that the proposed claim was clear of the
objections raised in the Final Action. On June 17, 1983 Mr. Davidson sub-
mitted an amendment in which permission was requested to cancel pages
containing claims 1 to 13 and substitute a new page containing the proposed
claim. We recommend entry of that amendment.
The Examiner has not had an opportunity to consider this claim during
normal prosecution. We recommend therefore that the application be
returned to him to assess its allowability with the above claim.
A. McDonough M.G. Brown S.D. Kot
Chairman Assistant Chairman Member
Patent Appeal Board
I have considered the recommendations made by the Patent Appeal Board.
Permission is granted to enter the amendment and the application is returned
to the Examiner for further consideration.
J.H:A. Gariepy
Commissioner of Patents
Dated at Hull, Quebec
this 5th, day of August, 1983
Agent for Applicant
A.E. MacRae &, Co.
Box 806, Station B
Ottawa, Ontario
KIP 5T4