[Clayart] Water

Hank Murrow via Clayart clayart at lists.clayartworld.com
Tue Feb 10 15:12:10 EST 2015


Dear Jim;

Your report is one of the most interesting 'slightly off topic; but not really' I have ever encountered on Clayart! Congratulations & Cheers, Hank in Eugene

BTW, my dad was the aerodynamicist for the Douglas C-47, DC-4, Skystreak & Skyrocket, and the Hughes H1 'Spruce goose'____ quite a portfolio. Having a potter for a first-born was a disappointment, yet I thrived despite it.

On Feb 10, 2015, at 9:34 AM, Jim Brown via Clayart <clayart at lists.clayartworld.com> wrote:

> The Boeing 707's were called "water buffaloes" - they had water injected
> into the engines on takeoff.  At max takeoff weight, the 707's would roll
> and roll and roll on takeoff - especially on hot days or higher elevations
> like Denver.  The engines were brought up to full power, brakes released
> and the water injectors hit - the increase in thrust was substantial and
> lasted until shortly after liftoff.  The only problem being that since
> there was only one tank for the water, the water would run out at the
> engines at slightly different times, meaning the 2 engines on one side of
> the aircraft would run out before the 2 on the other side.  This resulted
> in a very large decrease in power on one side of the aircraft and resulted
> in a marked yaw of the aircraft.
> 
> So you were rolling with a max load on hot/high day and you rolled and
> rolled and rolled and you are wondering, "Well, are we going to make it
> today?".  Just before the end of the runway you lift off and while still
> very close to the ground, the water cuts off on one side, the aircraft
> makes a sudden and marked yaw to one side.  The pilot, of course, puts in a
> lot of rudder to keep the aircraft straight and about that time the water
> runs out on the other side - with the marked yaw in the other direction and
> needing a rudder correction in the other direction.  A good pilot could
> time the rudder inputs and you would hardly notice the yaw but miss-time it
> and it made for an interesting takeoff.




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