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Subject:
360 Horizontal Stabilizer
From:
"C.L.Keller" <clkeller@burgoyne.com>
A couple of questions relating to the 360 H.S. and elevators:
(1) The manual doesn't give any good information about trimming the
inboard end of the elevators. It seems this should be done before
closing the elevators, but Marv's web site pictures make it look like he
closed them with the narrow - perhaps a quarter inch - gap between the
two surfaces. Marv?
(2) The manual suggests an outboard rib at the counterweight
station (pp 7-33, 7-34), but the SFB elevator includes no such thing.
Is this a remnant of the old stabilizer?
(3) In Marv's photos it appears the trim tab extends only to the BL
21 rib although the manual suggests the tab should extend to BL 24. Is
the shorter tab adequate?
(4) The manual gives the elevator deflection limits as +26, -11
degrees on pp 7-22 and 7-53, but in the next chapter (8-20) it calls for
+27, -13 degrees. Is the larger deflection left over from the old stab?
Charles Keller
[Charles, since most of the questions seem to be pointed at me, I'll try
to handle them here for you.
Re: trimming the inboard end of the elevators, it was recommended to
me by Orin to leave any trimming operations until absolutely required..
This goes for the stab skins as well. The i/b end of the elevators can
wait until you hang the rudder to insure that the lines are positioned
correctly. The closeout will happen after trimming.
That outboard rib you mentioned has been deleted in the MKII tail.
There was some confusion about the location of the trim tab due to the
placement of a rib in the elevator. I contacted the factory and spoke to
Doug Weeldryer about it, and he put me on hold and measured the tab on
the MKII factory demo plane. The dimension I used was based on that
measurement, and Doug assured me that there was plenty of authority at
that dimension. Don't forget, you're probably going to want to put a
potentiometer or resistor inline with the trim tab switch to give you
variable speed operation of the tab... normal tab speed at cruise is
reported to be pretty twitchy, that's another part of the reason the
tab is a bit smaller.
I believe that the +27/-13 in chapter 8 relates to the small tail. You must
remember that there are many parts of the manual which haven't been
updated since the MKII tail became standard equipment. I suspect this is
one of them. Perhaps one of our builders/fliers out there with the
original tail will chime in here and let us know if those are the specs
that they used. Given the extra area of the MKII elevators, it makes lots
of sense that the deflection requirements are less..
I hope this helps. <Marv> ]
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