Hi Dave,
I appreciate the "heads up" on the C-85 information in the Model D
Flight Manual. It is there,
as you say (and misleading). I reaffirm that the 415-D was not
produced with the C-85. The
415-E Model was the first Ercoupe produced with the C-85.
My files contain an 8-1/2 x 11 blueline of the ORIGINAL Model D Flight
Manual as signed by
Charles F. Dycer on June 13, 1947. Remind me to show you this when you
visit...my scanner
is not presently functional. Your copy also shows the same signature
and date on page 1!
The reality is that my blueline copy has the "Cockpit Check List" on
page 5, whereas in the
version Univair presently sells (and for some time has sold) the C-85
Operating Limitations
have been added. I would presume this addition was was subsequent to
FAA approval of
the E Model with the C-85 and subsequent to revisions to TCDS 718 and
787 allowing C-85
installation in earlier Ercoupes or conversion of original C-75 engines
to C-85 specification.
It is normally not permitted to make such revisions to a FAA-approved
Flight Manual without
subsequent review and I would have expected to see a different
signature or at least a later
date even if he personally approved such revisions to the original
415-D Flight Manual.
When the manual was "updated", C-85 performance data should have been
added, or at the
very least a note explaining that all performance information therein
was obtained with the
C-75 and props capable of 2050 to 2060 Static RPM.
If one goes to the 415-E and G Flight Manual to compare performance at
1400 lbs. gross with
85 HP and a wood prop turning 1950 RPM, the tables for Distance to
Take-off and Climb 50 ft.
are identical. The Distance to Land and Stop from a Height of 50 ft.
is identical even though
the 451-D approaches at 75 MPH and the 415-E & G with split elevator
approach at 70 MPH.
The latter data appears illogical. All other things being equal, the E
& G Models approaching
at 5 MPH less should stop in a shorter distance.
I find the Climb Data comparison absolutely fascinating, as it clearly
favors the C-75! I also
wonder why ERCO chose to provide no metal prop data for E & G Models
with the C-85.
Beginning at Sea Level and 0ºF, the 75 HP D-Model is climbing at 69 MPH
and 610 FPM. This
decreases with altitude and increasing temperature such that at 6000'
PA and 100ºF the rate of
climb has decreased to 240 FPM.
Beginning at Sea Level and 0ºF, the 85 HP E & G Models climb at 70 MPH
and 585 FPM. This
decreases with altitude and increasing temperature such that at 6000'
PA and 100ºF the rate of
climb has decreased to 215 FPM.
This seems to confirm, in the Ercoupe at least, that the C-85 was all
sizzle and no steak.
Best regards,
William R. Bayne
.____|-(o)-|____.
(Copyright 2009)
--
On Nov 19, 2009, at 22:02, [email protected] wrote:
Bill,
I have an on-line copy of the 415-D Aircraft Flight Manual that has
data for the C-85 on Page 5. C-75 is on page 4. I also have a newer
Univair copy somewhere, but I used the on-line one as my primary
reference. Thanks for the ordering information.
Dave
