One of the disadvantages of deleting the message (or part of the
message) responded to is unavailability of applicable context. Here
is the information from my earlier post (pertaining to the earlier,
non-aerodynamic trim system installed in Ercoupes Serials 213 thru
1622):
"Don's trim system is discussed at length in Ercoupe Service
Memorandum No. 19 of 4/26/46 (date from ESM No. 38). It says:
"...the natural trim speed in a glide with the controls and trim
device disconnected is now approximately 70 mph, a speed at which the
airplane can be maneuvered to a satisfactory landing by throttle alone".
Was it this ERCO information or some other information where you
believe I pointed "...out that this should be something controllable"?
WRB
--
----- Original Message -----
From: Ed Burkhead
To: [email protected]
Sent: Monday, August 30, 2010 1:13 PM
Subject: Re: [ercoupe-tech] trim tab requirements
On 2010-08-30 6:04 AM, John Cooper wrote:
OK, then why did Erco require the trim tab when installing the C-85 if
it is not necessary? For that matter, why did they introduce it at
all?
That was the time period when the FAA (and the industry) were
realizing it was a darn good idea to have a backup system for all
essential controls.
The rudders act as a backup system to the ailerons. On most
aircraft, the ailerons can do their job without the rudders (though
sloppily).
If the elevator cable(s) break, the spring trim system provides no
backup at all. You are dependent on the plane's natural pitch
stability and trim with a loose elevator. Bill points out that this
should be something controllable. Me, I don't know.
However, with the aerodynamic trim tab, the plane should remain
controllable in pitch and airspeed sufficient to make a walk-away
landing. With a skilled pilot, the aerodynamic trim should let you
get down undamaged.
Ed
