From: gaynier@elec.uq.oz.au (Ron Gaynier)
Subject: Re: Silver 'C' Duration, Was "What to do on long flights?"
Organization: Prentice Centre, University of Queensland
Date: Thu, 10 Sep 1992 00:08:10 GMT

In <1992Sep9.113524.2610@dsg.cs.tcd.ie> sloubtin@dsg.cs.tcd.ie (Sylvain Louboutin) writes:

"|">In article <gaynier.715824990@s1.elec.uq.oz.au>, gaynier@elec.uq.oz.au 
"|">(Ron Gaynier) writes...
"|">> 
"|">>I had my own long flight yesterday. My 5 hour duration flight for my 
"|">silver 'C'.
"|">lines deleted....
"|">>I flew into 8 knots up. So there I was caught with my pants down, harness 
"|">undone, plastic
"|">>bladder out of a wine box between my legs, trying to center the thermal.

"|"not to forget a kind of portable loo (for male pilots only) which you

stuff deleted.....

"|"it is roughly made of
"|"small bags connected to a sort of modified condoms (it's difficult to
"|"describe but you can get the idea...)   

Our club's new LS7 has a tube that discharges to the outside (peetot?)

"|"some figures (sorry if it look gross,  but it is definitely an
"|"important issue when you fly gliders; disclaimer: I am not a MD,  these
"|"figures come from experience and discussion with MDs;  I'd love to see
"|"some specialists' opinion about this):  a bladder fills up at a rate
"|"which is roughly between 200 cc/hour (when you have drunk a lot of
"|"water) down to 50 cc / hour (but it's definitely not a good idea to
"|"dehydrate yourself to that point);   let's say that 100 to 150 cc/hour
"|"is OK.  The average bladder can hold around 450 cc (it starts to be
"|"really uncomfortable earlier for most people);  some lucky people have
"|"bladders twice this size (born to be glider pilots :-)  so,  if you are
"|"an average person,  drinking a reasonable amount of water,  you can fly
"|"comfortably for about 4 hours (I believe it can be really dangerous to
"|"either dehydrate yourself to try to avoid the problem or to fly with a
"|"full bladder,  which is not good for concentration).  So why is this
"|"problem never mentioned to student pilots who are supposed to
"|"eventually fly their Silver "C" duration (and later long cross country
"|"flights????  Everybody hacks his/her own solution and I very rarely
"|"heard anybody talking about it as if the problem did not exist...

You've neglected perspiration (sensible and insensible) which increases with
altitude (?). Just as a note, I consumed  1 1/2 litres of water during the 6 hours
of my flight (also a granola bar and some kiwi fruit), it wasn't a very hot day 
but is was blue so I wasn't under any clouds. Sorry, I didn't measure the amount 
of fluid that was in the bag so I don't know my personal bladder size. Not that 
its anyone elses business;-)

One of the most experienced glider pilots I know recommends drinking large amounts
of water before and during breakfast (as much as you can stand) and then nothing else 
until during the flight. He carries about 2 litres with him (to drink, I don't know his
bladder size;-). Using this method I have to urinate by the time I'm ready to launch 
which gives me an empty bladder to start, yet I feel fine and assume I'm still adequately 
hydrated from all the water earlier.  Any medical opinions on this method?

Of course, begin drinking BEFORE you begin to feel thirsty.

Ron Gaynier
Newsgroups: rec.aviation