Re: Wings and back plates

[rockport@xxxxxxxxxxxxx (John Grogan)]

On Jan 06, 1998 05:45:45, 'Roy F Parrott <RoyParrott@xxxxxxxxxxxxxx>'
wrote: 
 
 
>>> The un-bungeed wing does not flap about.  Because it is free to move 
>around, it can flow in the slipstream.  Also when inflated, the wing wraps

>around the tanks, thereby providing lift to the immediate source of
weight. 
>If the bag is punctured, lift can still be provided as gas is not forced 
>out.  The wing should be re-enforced inside to help prevent a puncture. 
>Also, second bladders are a big No-No. << 
> 
>I assume that the second bladder is with the shell along with the first
one 
>and is not of the redundant type. 
> 
>So why are second bladders a big no-no?  (in learning mode) 
 
The big problem with the second bladder is that it is in the same space as
the first.  This  means that you cannot fully inflate both together - in
other words you can inflate both to half capacity only as the volume
available is constant.  This shows that extra lift is a misnomer.  Your
100lb wing will still only give 50lb's lift. 
 
The other problem with a second bladder is that it's another hose with
another LP port used on your reg - hence more failure points.  You must
also consider where to stash the hose, is it accesable etc.  In other
words, it creates more problems than it aims to solve. 
 
The redundancy is provided by your drysuit.  Ideally, you should use a
tri-laminate membrane suit.  In the event of a wing failure, your suit can
provide the lift needed.  In normal circumstances, lift should be provided
by the wing and not the suit.  Only put enough air in the suit to relieve
squeeze. 
 
Your choice of equipment is also important here.  For example, if using
stage bottles, ideally they should be aluminium and not steel (less
weight).  If proper equpment is used and you are correctly weighted, then
your suit will provide more than enough lift. 
 
Hope this helps, 
John.