REFLECTOR: Elevator attachment hinges and alignment

Tue Jan 31 19:21:03 CST 2006

Hi All,

I have a small piece to add to this thread, especially since I have just
today epoxied in my elevator hinge arms.  

First I agree a lot with you, Pat, that the elevator attach method
spelled out in the manual is not very precise.  It says basically line
up the under surface of the elevator with the undersurface of the
canard, but the canard surface is curved.  Malcolm Collier and Hangar 18
let me use a jig he has that any future builder could make.  Take a
piece of plywood about 18 long and about 4 inches tall.   (Make 6 of
these.) Curve the first 12 inches or so to cradle the bottom face of the
canard to include both a little bit of the leading edge and the aft
curving edge of the canard.  With a jig saw, follow that aft contour of
the carnard.  There is a one inch or so space between the end of carnard
and beginning of the elevator that will accommodate you doing this.
Then make the remaining 6 inches or so flat to mate with the elevator
surface. Then shim the elevator half of the jig until you are happy with
the relative allignment.   

5 min epoxy the whole mess making sure you have the .05 gap (or whatever
call out) for the gap between canard and elv.  File down a stir stick to
a mic'd .05; chop it up into 5 or 6 pcs and scotch tape them down to get
a good consistent span-wise .05 gap so as to hopefully get the maximum
designed elevator movement.  Then flip it over (carefully) to attach the
hinge arms.    Be sure to pick jig attach points where the hinges will
not be in the way!  

I don't know about the rest of y'all, but I also found it very very
difficult to taper evenly the aft edge of the carnard front body down to
030.  This measurement too is a clearance issue that affects elevator
throw limits, and shaping/holding a sanding tool here is next to
impossible.  I've got no tricks for this one.  Several times I got too
sharp and had to loose overall for'd/aft length because of it... and my
taper sucks.  I hope to fix it after my hinge arms cure.     

I have another elevator attach discovery to share.  I have an XL-5.  I
have two construction manuals to reference (1996 & 2003).  If you
haven't attached your elevator to your canard yet, look at your hinge
bracket and see which side of the hinge bracket has the spacer collar
that is a machined portion of the inserted brass bushing.  In the 1996
construction book, the drawings show that the hinge arm should lay over
the top of the hinge bracket with the collar located between them. In my
2003 book (and 2005 kit) that brass insert in the hinge bracket is put
in the opposite way (backwards?) and the book was revised to show that
you attach the hinge arm "next to" and not "over the top of" the footing
of the hinge bracket.  Not a big deal maybe, but it is no big deal
either to press out that bushing and install it so the bracket and arm
assembly will be more closely alligned with the stress/load transfer
between the two surfaces.  Also the inboard-most hinge arm attach screw
gets in the way of the torque tube insertion if you leave them as is.

I've got pics of that jig if anyone wants it.  I can't take credit for
the above, but I will take all the blame for passing anything along
that's not correct.  Nothing here is intended to be official, or
correct, or better, nor do I encourage deviation from written
documentation.  When in doubt call the factory.  ...just MY two cents
(not from H-18) and it is in thanks to people who have helped me along
the way who I can't pay back in kind.  

Still sewing seat covers, and learning about paint chemistry in my spare
hours,  
Terry     

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Alex Balic
Sent: Tuesday, January 31, 2006 9:58 AM
To: 'Velocity Aircraft Owners and Builders list'
Subject: RE: REFLECTOR: Elevator Trim Spring

I definitely agree with you there Pat- although I remember over the
years several discussions where folks would comment that the position of
their elevator in cruise was abnormally deflected up- just thought that
would be the first place to check- you can of course fly that way by
adjusting the spring position (which I agree should be more accurately
indicated in the
plans) but flying with the elevator reflexed more than a few degrees in
cruise is an indication of an out of rig aircraft. As for the incidence
gauges- mine were pretty basic, and the one for the wing was slightly
warped, (although I corrected that) so if all errors went in the same
direction, the canard incidence on any one aircraft could vary by a few
degrees, and on that stubby little airfoil, that would create a big
change in lift. Of course if the actual position of the elevator in
cruise is fine, and you are just out of trim, then of course, they would
need to adjust the spring position.

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Pat Shea
Sent: Tuesday, January 31, 2006 12:37 AM
To: Velocity Aircraft Owners and Builders list
Subject: RE: REFLECTOR: Elevator Trim Spring

Alex,

The relationship between the wing and canard is
relatively accurately set by the incidence gauges. On
the other hand, the neutral position of the elevator
trim system is very roughly set by the TLAR method
(That Looks About Right). If I recall correctly, the
directions read something like "Remember, you'll need
more up trim (elevator trailing edge down) than down
trim." Consequently, I suspect most builders end up w/
too much up trim and run out of down trim at high
speeds. This is by no means any indication that the
wing to canard configuration isn't correct.

It's been my experience that the standard elevator
trim system has enough throw to cover both the high
and low speed ends of the envelope - you just need to
fine tune the neutral position.

Pat XLRG

--- Alex Balic <alex157 at pwhome.com> wrote:

> I was under the impression that the starship used
> variable sweep on the
> canard, not variable incidence- this increased the
> lift authority at slow
> speed (extended)  and reduced drag at high speed
> (swept) I agree that there
> is a fundamental design feature to keep the canard
> stalling before the main
> wing, but the particular aircraft that we are
> discussing might need an
> adjustment of canard incidence to correct the pitch
> authority problem
> without going so far as to allow the wing to stall
> before the canard-
> really, a close and precise gauge of the incidences
> relative to each other
> will determine if adjustment is needed..

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