> Andy Ross replied 

> Vivian Meazza wrote:
> > wastegate-mp="18.32"
> > [...]
> > mp-osi = 26.050 - does the "wastegate" work? - is this psi?
> 
> The units are absolute pressure in inches of mercury (I 
> honestly don't know what the "-osi" suffix means).  The 
> wastegate should indeed work. However, it is an overpressure 
> release valve.  It cannot suck a vacuum in the manifold if 
> ambient pressure is already higher than its setting. :)
> 
> Typical values for the wastegate are going to be 
> significantly higher than one atmosphere (== ~28" Hg), but 
> I'm sure that varies with supercharger design.  Probably some 
> aircraft don't have them at all.
> 
> > The model does not fly, failing to accelerate (insufficient prop 
> > thrust), with the following output data when throttle = 1:
> 
> Outside the wastegate setting (which is a noop in this case) 
> nothing looks clearly incorrect.  Can you post the whole file 
> so I can try it?
> 
> > I've tried increasing pitch, to no avail. I've tried 
> > <takeoff-power="1100" takeoff-rpm="1360" - then YASim crashes
> 
> That's clearly a bug; no configuration should be causing 
> crashes*. Can you be more specific about how to reproduce it?
> 
> Andy
> 
> * Well, not quite: you can crash YASim by mapping a property to an
>   incorrect object -- THROTTLE on a wing, for example.  It should
>   check for validity at parse time, but doesn't.
 
Osi - ounces per sq in :-) more likely a typo for psi. I'm just going to try
the wastegate (or, more strictly, boost control valve)  using absolute
pressure. Slightly odd, that, manifold pressures are usually referred to as
overpressure.

YASim crashes, or perhaps, fails to converge, just by attempting to run with
<takeoff-power="1100" takeoff-rpm="1360">

Thanks for the quick response.

Vivian Meazza



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