REFLECTOR: Sump Tank Design Change Suggestion

Fri Aug 4 14:17:44 CDT 2006

Hey Jerry,

Directly it doesn't address the radius.  As we all know, the bid tape does
not want to make that sharp corner.

For the lay-up I used the universal, poor mans vacuum bag.  I laid up the
glass, put on the peel ply, and then covered it all with the Reynolds Wrap.
With the plastic wrap on I worked out all the air bubbles.

Now for the indirect...

Because the seam was sealed on the inside, I didn't have to worry about air
migrating from the inside of the sump, through the seam, and under my glass.

The plastic wrap has an airtight barrier on the glass.  Carefully work out
the bubbles.  Air can't get back in the lay-up so you can't get bubbles and
the glass can't lift.  The unruly glass has been conquered and we stand
proudly, and defiantly over the sump tank, masters of our domain.

This technique works well when the epoxy has started to thicken a bit.  I
wet the glass out and let it set for an hour before I apply it.  If you try
when the epoxy is too fresh, then the plastic wrap won't stick.  Wait too
long and it sticks too easy and is hard to work with.  Once cured, it pulls
off with no effort.

It has the added benefit of drawing excess epoxy above the peel ply; just
like the vacuum bag does.

Andy

________________________________

From: Brainard, Jerry [mailto:Jerry.Brainard at anthem.com] 
Sent: Friday, August 04, 2006 2:52 PM
To: amillin at sbcglobal.net; Velocity Aircraft Owners and Builders list
Subject: RE: REFLECTOR: Sump Tank Design Change Suggestion

I see how this improves the seal, but how does it address the lack of radius
for the external BID that Hiroo questioned.

- jerry

________________________________

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Andy Millin
Sent: Friday, August 04, 2006 2:18 PM
To: 'Velocity Aircraft Owners and Builders list'
Subject: Re: REFLECTOR: Sump Tank Design Change Suggestion

Hiroo,

When it came time to make my sump, I was concerned about this very thing.  I
built a flange on the inside of the sump.

Click to Enlarge <http://www.kal-soft.com/velocity/images/pic561l.jpg> 

It gave me plenty of surface area to make the seal on the inside of the
tank.  I wanted the bid tape to be structural only.

Andy

________________________________

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Hiroo Umeno
Sent: Friday, August 04, 2006 2:03 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Sump Tank Design Change Suggestion

I have the similar arrangements.  What I was talking about was not the
mounting of the sump tank but the construction method of the tank itself.
Perhaps the kit design has changed since 1999?

Hiroo

________________________________

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Lawrence J. Epstein,MD
Sent: Friday, August 04, 2006 10:50 AM
To: 'Velocity Aircraft Owners and Builders list'
Subject: Re: REFLECTOR: Sump Tank Design Change Suggestion

What I have done is make 2 hardpoints on the floor of the fuselage under the
forward edge of the Sump tank. I then made "legs" using small mixing cups as
a mold and I am putting a rib on each leg to the sump. I am then securing
the sump legs to the floor. The tank is then supported @ 4 points.

Larry Epstein

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Hiroo Umeno
Sent: Friday, August 04, 2006 1:30 PM
To: reflector at tvbf.org
Subject: REFLECTOR: Sump Tank Design Change Suggestion

After my last "incident" on first engine run related to my shoddy
craftsmanship on the sump tank, I started thinking.

Admittedly, it was mostly due to the crappy job I did in joining the sump
tank tub with the side wall.  However, I am thinking that the original
design also had some contributing factor to it.  My kit came with sump tank
that had two parts: the part that looked like a tub and a flat sheet of
fiberglass plate that was to be the "back wall" that was oversized and
needed to be trimmed to fit.

What this forces the builders to do is to lay the tub over the sheet, mark
the tub outline on the sheet, cut to fit, then lay up the edges to join the
halves.  This layup is a bit tricky since the plate is rather thin and even
after sanding the edges off, it remains a fairly sharp radius.  To make the
matter worse, the tub side wall does not meet the plate at 90 degrees making
the fiberglass tape wrap the approximately 100 degree corner as it join the
pieces.  It is very easy to get delamination or bubbles in the lay up which,
as I leaned the hard way, is a really bad thing for something that contains
fuel.

My suggestion is to change the sump tank design such that two tub halves are
mated flat at the center much like how the nose gear pants are joined left
and right.  This will enable the joining lay up to be done on a relatively
flat side-wall and make it much less problematic for first-time builders
like me.

Hiroo

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