The ones that I have seen use a clear plastic tube made for safety
covers for fluorescent lighting tubes. They are approximately 1.7
inches in diameter and 4 feet long. Light weight and completely clear.

Keep in mind also that the height specification that Todd mentions is
height above the wing.

Larry Goddard
"Zero One"
USA





Todd Pattist wrote:

Flavio Formosa wrote:

I remember having once seen on 'Soaring' an article
about a clever (albeit complicate) ballasting system
designed for an LS6, where water came from the mains
supply, but with a vertical spill pipe of a precise
length inserted between the supply and the glider,
to avoid exceedingly high pressure and wing shell bursting.
Anyone using this system for integral tanks with bottom
filling (LS8 style)? What's the advisable spill pipe
height for a quick but safe fill?

Spill pipe height is determined by the maximum pressure your
wing can withstand. It's usually specified in your manual.
Mine says one meter. It is important, if using a high
pressure source, to absolutely prevent the pressure from
exceeding the maximum value. I've heard the awful crack of
a splitting wing when it gets too high.

If your high pressure source can produce a relatively high
flow rate, you will want a large diameter spill pipe. A
transparent one would be nice to monitor pressure as you
fill.

The spill pipe is often created with a simple T-fitting.
It's a good idea to orient the T so the pressure comes in
the bottom on one side of the straight through leg of the T,
the spill pipe is vertically straight through on the other
side of the straight through leg and the feed for your wing
tank is from the ninety degree leg of the T.

I've also considered buying one of those pressure reducers
sold for motorhomes to keep their internal plastic plumbing
from bursting. They keep pressure below 40 psi, which is
still way too high, but perhaps they could be modified by
changing a spring. I'd still use the spill pipe, but I'd
worry less.

Todd Pattist - "WH" Ventus C
(Remove DONTSPAMME from address to email reply.)