Good points. Next time I go out, I'll have to check the hands off speeds with
different trim configurations. I haven't tried that before except to always
trim the pressure off the yoke. I'll trim for landing, power off and let go of
the controls (at a safe attitude) and see what speed it stabilizes at. Same
with a climb with trim set at take off and land with full power. Should be fun.
Bart
--- In [email protected], William R. Bayne <ercog...@...> wrote:
>
>
> Hi Bart, Ed
>
> In a January 18, 2009, email to Maynard Smith, I stated:
>
> "...with the trim set for "cruise" the trim tab is "high" (although
> neutral) and
> therefore with full "up" elevator there is greater effect from the
> limited
> movement available for flare and speed scrubbing. That would further
> reduce touchdown speed a bit and perhaps offer a worthwhile
> improvement in response of the 415-D (with only 9¼ up elevator
> available).
>
> Since the above is in reference to touchdown after the yoke has been
> moved
> fully rearward, it seems obvious that the effect on "minimum speed"
> would also
> affect the indicated speed at which the stall occurs.
>
> With specific reference to the Ercoupe design, consider flying rule
> #63a:
>
> If the Ercoupe departs controlled flight, cut the throttle to
> approximately
> 1700 RPM and release the controls. In other than significant
> turbulence,
> it should level out (steady itself side to side) trimable to
> approximately a 200
> FPM descent.
>
> The pilot may then climb or descent by adjusting throttle and trim for
> a forward
> speed of around 70 MPH and, if the bird is rigged correctly, know
> (preferably
> from prior VFR verification) that a heading can be selected and
> maintained with
> gentle (one finger) left-right input without risking the dreaded
> "graveyard spiral".
>
> ÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅÅ
>
> The above speeds, etc. are from memory...determine what your indicated
> air speed is
> under stated conditions. Here's some basic checks on if your plane is
> properly rigged:
>
> Per Ercoupe Service Memorandum No. 19 (crank style trim on instrument
> panel thru
> Serial No. 1622 trims entire elevator...no movable trim tab as
> originally manufactured):
>
> Item, 6-7: "Flight check should show a glide speed of 68-70 MPH with
> trim unit
> set at "nose up".
>
> Item 7-3: "Change elevator trailing edge to function as a fixed trim
> tab, to obtain
> proper glide speed."
>
> [see also Ercoupe Service Memorandum No. 35, Item 14]
>
> Per Ercoupe Service Memorandum No. 25 (applicable to lever style trim
> on left inner
> fuselage) on 415-C Serial No. 1623 up, AND "Airliner Quadrant" trim
> mounted at
> center bottom of the instrument panel on all 415-D and 415-CD (as
> manufactured...
> WITHOUT SPLIT ELEVATOR):
>
> "With the trim crank handle full back ["nose up"-WRB]...a glide, power
> off, at 58
> mph and a 55 mph climb with power on." [should result]
>
> [see also Ercoupe Service Memorandum No. 35, Item 14]
>
> Per Ercoupe Service Memorandum No. 35 (applicable to lever style trim
> on left inner
> fuselage) on 415-C Serial No. 1623 up, AND "Airliner Quadrant" trim
> mounted at
> center bottom of the instrument panel on all 415-D and 415-CD (as
> manufactured...
> WITHOUT SPLIT ELEVATOR):
>
> Item 15: "Effective about Ercoupe No. 3882, the elevator trailing
> edge has been
> bent downward 3¼Êon production aircraft. It was found that this
> modification makes
> it easier to bring the airplane within to (sic) the desired glide
> characteristics."
>
> Per Ercoupe Service Memorandum No. 38 (applicable to lever style trim
> on left inner
> fuselage) on 415-C Serial No. 1623 up, AND "Airliner Quadrant" trim
> mounted at
> center bottom of the instrument panel on all 415-D and 415-CD (as
> manufactured...
> WITHOUT SPLIT ELEVATOR):
>
> Item 11.b.(3) Note: "...with the trim crank handle full back ["nose
> up" position], the
> airplane is trimmed for a power-off glide at 65-75 MPH and a full
> power climb of
> 60-70 MPH."
>
> It is presumed that these later values take precedence over those in
> ESM-25.
>
> Per Ercoupe Service Memorandum No. 35A (applicable to "Airliner
> Quadrant" trim
> mounted at center bottom of the instrument panel or to all 415 series
> airframes to which
> a split elevator has been installed:
>
> Item 4a: "Bend the fixed trailing edge of the left panel of the
> elevator down 11-1/2¼".
> [WRB note-this adjustment could cause "right wing drop"
> after
> stall!]
>
> Item 4b: "Power off minimum airspeed" is 60 M.P.H." [when "lower
> speed warning
> cushion spring is encountered...if IAS below, shorten;
> if
> above, lengthen]
>
> Regards,
>
> William R. Bayne
> .____|-(o)-|____.
> (Copyright 2009)
>
> --
>
>
> On Aug 15, 2009, at 10:01, Ed Burkhead wrote:
>
> >
> >
> > Bart accidentally sent this to me, only. (Y'all be sure to send to the
> > forum, ercoupe-tech@ and not ercoupe-tech-owner@)
> >
> > I can see that there could be a slight difference in minimum speed due
> > to
> > trim tab position, Bart, but that's way bigger an effect than I would
> > expect! Has anyone else ever measured this?
> >
> > Bart wrote:
> >>
> >> You can get the stall speed to change depending on where the elevator
> >> trim
> > is set. With
> >> power off and the trim in approximately cruise position, the stall, or
> > "mush" occurs in my
> >> airplane at just below 50 mph. If I trim for landing(nose up trim)the
> > mush occurs at a little
> >> above 50 mph. If I trim full nose down, a stall occurs at a little
> >> below
> > 45 mph with a gentle
> >> stall buffet but no "break". If you roll in some aileron during a
> >> stall
> > in this configuration,
> >> you get the buffet then a slight break with some apparent rotation
> >> which
> > looks like a spin,
> >> but it is not a spin. It's a spiral, and you can stop it by just
> >> rolling
> > wings level and relaxing
> >> back pressure.
> >> Which leads me to overall flying rule #63. If the aircraft departs
> > controlled flight, neutralize
> >> the controls until you see something you recognize, then recover.
> >> Bart
> >>
> >
> >
> >
> >
> >
> > ------------------------------------
> >
> > Yahoo! Groups Links
> >
> >
> >
>
