DeltaDeltaT, like delta T, cant be measured from any absolute point, but is
a degree measurment between points.

We assume that the behavior going from -30 to -20 is the same as from 90 to
100 (assume all degree C).  This is not exactly true but very close.

From: <echristley@nc.rr.com>
Subject: [FlyRotary] Re: Air Density at altitude
> Wouldn't the percentage change in DeltaT (DeltaDeltaT?) have to be
measured from absolute 0?  An 80degree change would then
represent...what?... about 20%?
> From: Ed Anderson <eanderson@carolina.rr.com>
> Subject: [FlyRotary] Re: Air Density at altitude
> >  Heat transfer equation Q =W*DeltaT*Cp, with W = mass flow down
> > by 30%.  So to get rid of the same Q of heat (and since Cp doesn't
> > change that much)  it would appear that means the delta T term
> > would need to increase by 30% for Q quantity to remain the same.
> > But, I don't know exactly how a 79Deg colder incoming air would
> > affect the Delta T term.