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Bill
I could not agree more, John has always been a great resource for me. When he does not have a in house solution for a part or problem, or even if he does, he always gives me other options from his competitors. I probably have talked way to long on the phone with him and yet he is always kind and full of information. I do not want to lose John in this forum, he is too valuable. This is not a forum for personal attacks, and I too will not put up with it!
Chuck
94191
WILLIAM BIGGS <[EMAIL PROTECTED]> wrote:
Bill,
This is a friendly forum. Your personal attacks are unwarranted and
unwelcomed. I am personally offended.
John's makes a living by supporting coupes. His opinoins are different from yours but he does not force them on us. Your comments could adversly effect his business.
Let me formulate my own decision on what is the correct information.
Am I alone in this feeling?
Bill Biggs
From: "Ed Burkhead" <[EMAIL PROTECTED]>
Reply-To: "Ed Burkhead" <[EMAIL PROTECTED]>
To: "Ctech" <[email protected]>
Subject: FW: [COUPERS-TECH] C-85 STC, Performance, Props
Date: Thu, 23 Feb 2006 20:40:49 -0600
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>
>
>
>
>This message was automatically forwarded on behalf of Bill Bayne. Please
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>-----Original Message-----
>From: William R. Bayne [mailto:[EMAIL PROTECTED]
>Sent: Thursday, February 23, 2006 6:18 PM
>To: Ed Burkhead
>Subject: Re: [COUPERS-TECH] C-85 STC, Performance, Props
>
>
>
>rlytech
>
>On Feb 23, 2006, at 10:23, John Cooper wrote:
>
> > At 12:31 AM 2/23/2006, WRB wrote:
> >> The C-90 is a 90 hp engine rated at 95 hp for one minute (take-off).
> >> I
> >> believe the prop would have to be pretty close to a "climb" pitch
> >> for the
> >> engine to turn
necessary rpm to develop 95 hp in a cruise-climb
> >> configuration.
> >
> > It's not that simple. A prop that would allow you to turn 2625 RPM
> > (the rpm at which the 95 hp rating is achieved) would be way beyond
> > extreme cruise
>
>I presume that "cruise" is a typo and that you meant "climb" here
>(which would somewhat agree with what I said, and not appear to
>contradict it), otherwise this sentence is gibberish.
>
> > and would only allow something like 50% power in level cruise before
> > it overspeeded. Such a prop would not meet the static RPM requirements
> > and as such would be an unairworthy combination. To say nothing of
> > the 75mph top cruise speed...
>
> > TCDS A-787 lists 2475 as the RPM limit for the C90 installation.
> > Period, end of statement.
> >
>John, your reference is to
a "real" C-90, as installed in the Forney,
>Alon and M10. When I reference C-90 data, it was to illustrate a
>certain range of rpm or power previously established as safe; and not
>to invoke inapplicable regulatory limits such as you picked out to
>refer. If you read the subject of this thread, it begins "C-85 STC",
>and our engine under discussion remains, officially, a C-85, redlined
>at 2575 rpm.
>
> > On other aircraft using the C90 that do have provisions for the 95 hp
> > takeoff limit, the ONLY prop for which this is allowed (generally-
> > there may be exceptions) is the Beech Roby adjustable prop. That prop
> > is not certified for use on a C90 equipped "ercoupe". Bottom line,
> > without a field approval and the Beech prop, the 95 hp takeoff limit
> > is out of reach.
>
>I see the cup half full, not half
empty. For a C-90, field approval
>and Beech prop, 95 hp takeoff limit is in reach!
> >
> >> ...The two engines are mechanically identical except for the
> >> recommended rpm limits, which Erco
> >> ignored.
> >
> > I don't know where you get that idea from.
>
>I got the "idea" of the engines (C-75 vs C-85) being mechanically
>identical from the Continental parts book, and from extrapolating
>credible early postwar 75 hp Ercoupe performance data.
>
> > The TCDS clearly states "Engine Limits: For all operations, 2275 RPM
> > (75 hp)." Further more, the static RPM limits prohibit use of a prop
> > that would allow operation significantly above 2275 in all
> > circumstances except a dive.
> >
> > What Fred may have done in the privacy of his own home does not in any
> > way overrule the
published limitations.
> >
> > John Cooper, A&P
> > Skyport Services
>
>To use your words, "who flys like that"? This is not the first time
>you have used your considerable experience and training to divert an
>exchange of useful information into a bureaucratic dead end of little
>relevance.
>
>To substantiate my earlier statements, and make absolutely clear how
>your strangely absolute assertions in the last two sentences above
>conflict with the "real world", I quote part of a letter to me from
>Fred Weick dated June 12, 1986 (yes, I have the original on his
>letterhead) in which he responds to (my) earlier questions:
>
> "5. The Continental C-75 vs C-85 engines make a special story.
>They
>were the same engine physically
> except that the 85 had a slightly larger venturi and the next size
>larger jet in
the carburetor. The 75 hp
> was rated at 2275 rpm and the 85 hp at 2550 if I remember correctly.
>
>Being an engineer, I wanted to get
> as much performance from the rated power as I could. At any given
>rpm, the 85 carburetor gave at full
> throttle only about one percent more power than the 75 carburetor.
>I
>used the 75 hp rating but selected a
> prop (metal by that time) that would turn up just about the full
>power
>just under the 2275 red line at the
> max rate of climb. You could then cruise just under the red line
>legitimately. With wide open throttle it
> would turn up to about 2550 rpm which was quite satisfactory
>structurally. Many customers wanted the
> 85 hp engine, however, so we just gave them what was essentially the
>
>same engine with slightly larger
> jet and venturi in the carburetor and an 85
hp name plate. With the
>
>same propeller the top speed wide
> open then occurred at the legitimate 2550 rpm and the climb
>performance was about the same.
> As I remember it the top speed with the steel main gear was
>likely to
>run from about 125 to 127 mph
> with the plane fairly light (just the pilot). When we changed to
>the
>forged aluminum alloy arm which sort
> of wrapped around the wheel so that it would have a small overall
>width for the proposed retractible
> model, the drag was higher and the max speed was 2 or 3 mph lower."
>
>My earlier point, made absolutely clear in Fred's own words, was that
>"standard" wood props fitted to early postwar production 75 hp Ercoupes
>were of a pitch to allow almost 85 hp to be produced at full throttle.
>The portions of TC 718 relevant to C-75 performance are today as they
>were then. I
spoke with reference to REAL Ercoupes, as actually tested
>and duly "CAA certified", as then actually sold and operated by their
>owners.
>
>An A&P or IA who will not use his knowledge and experience to help me
>make my bird meet MY mission safely at minimum cost under the rules is
>a waste of my time and money. I heard once that college teaches you
>the rules, and experience teaches you the exceptions; and that most of
>the money is in the exceptions.
>Who hires a professional to tell them "you can't do that" (maybe the
>FAA). Such a mind set is self-fulfilling.
>
>A TCDS is mere paper (although very expensive paper to the owner)
>churned out by bureaucratic drones purported as infallible and of such
>absolute authority as divine commandments. In actuality, there is
>"wiggle room" there (even between FAA FSDOs). It would be sad
if
>Skyport's tradition of innovation is ended by management that perceives
>only that which can not be done.
>
>Regards,
>
> William R. Bayne
><____|-(o)-|____>
> (Copyright 2004)
>
>
>
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