REFLECTOR: Unexpected door opening

Alex Balic velocity_pilot at verizon.net
Fri Jun 5 21:05:24 CDT 2009


I have some carbon fiber arrow shaft pieces in there for mine- got an arrow
on sale at Wal-Mart for $ 2.99- would make about 6 or 8  tubes I would
think. works great- sort of self lubricating, and no measurable weight.

 

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From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Scott Baker
Sent: Monday, July 20, 2009 7:00 PM
To: Jim Agnew; Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Unexpected door opening

 

I think the liklihood of four (4) areas of failed fiberglass in the receiver
areas is slim to none.

Not engaging the pins into the receiver - likely if the door handle is not
rotated to its fully closed position.  Definately a possibility if there is
no micro switch and warning light to tell the pilot that the pins are not
fully engaged.

Good point on the possible problem of using wooden dowels as a "pin
extension".  If the dowels were to become stuck in the tube and remain in
contact with the micro switch, it would cause a false "door locked"
indication (absence of a door ajar warning); however I would hope that we
would recognize this situation following start and taxi (meaning we want to
verify the door ajar warning should be ON with the door open).

SB

----- Original Message ----- 

From: Jim Agnew <mailto:jim_agnew_2 at yahoo.com>  

To: Velocity Aircraft <mailto:reflector at tvbf.org>  Owners and Builders list 

Sent: Friday, June 05, 2009 5:39 PM

Subject: Re: REFLECTOR: Unexpected door opening

 

Al,

 

There are several failure modes for the door latches.  First the tubes that
accept the latch pins could fail I.E., part from the fiberglass.  Second the
latch pins may not be deep enough into the tubes so the stress is on the
flat portion and not the tapered part that will try to push itself out.
Third the latch pin can unscrew from the push rod (I know one of mine did
even with locktite on the threads, I now use RED Locktite on them).  

 

I have auto locking so closing the latches automatically locks them and you
must pull up on the door lock before you can move the handle.

 

As far as the door warning switches go I only have one in the forward center
pin location with a nylon mushroom button that activates a roller micro
switch.  I know a lot are in the bottom tubes with wood rods that can swell
from water and in the perfect place to collect dirt that can jam them.  

 

Just food for thought.

 

JIm
 

James F. Agnew

Jim_Agnew_2 at Yahoo.Com

Tampa, FL

Velocity 173 Elite Aircraft Completed & Flying

 

 


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From: Al Gietzen <ALVentures at cox.net>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Sent: Friday, June 5, 2009 1:48:33 PM
Subject: Re: REFLECTOR: Unexpected door opening

And for those who at the end of your personal deliberations who would still
opt for the gull wing, would something as simple as a deadbolt (weighing
only a few ounces) serve as a fail-safe back-up to the traditional lock
assembly?  Thanks for your thoughts.

 Robin 

Robin;

 

My thought is that we essentially have 4 'deadbolts' in the current
configuration.  We simply need a 'dead sure' way of knowing they are in
place.

 

My further observation is (added to by my experience flying home with a
temporary door) that net outward forces on the door in flight are relatively
small - at least compared to the strength of the four latches. I think there
is likely some negative (outward) pressure over much of the door, likely
stronger toward the front edge, and some positive (inward) pressure in the
area of the strake extension, and its junction. 

 

I have no idea if there are forces due to small distortion of the fuselage
during flight that may work to move the latch pins out of the tubes, but it
is not impossible.

 

FWIW,

 

Al


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