REFLECTOR: Sump Tank Design Change Suggestion

[Andy Millin]

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