Re: Prop mass and bsfc figures for YASim

> -----Original Message-----
> From: Lee Elliott <[email protected]>
> Sent: Sunday, 6. Feb 2005 15:54 -0500
> To: Flight dynamics model discussions
<[email protected]>
> Subject: Re: [Flightgear-flightmodel] Prop mass and bsfc figures for
YASim
> 
> On Saturday 05 February 2005 17:02, Jim Wilson wrote:
> > > -----Original Message-----
> > > From: Lee Elliott <[email protected]>
> > > Sent: Saturday, 5. Feb 2005 8:27 -0500
> > > To: [email protected]
> > > Subject: [Flightgear-flightmodel] Prop mass and bsfc figures
> > > for
> >
> > YASim
> >
> > > Hello all,
> > >
> > > I\\\'m looking for some prop mass and turbine engine bsfc
> > > figures for the SR-45 I\\\'ve been working on.
> > >
> > > I\\\'ve got a flying fdm using guesswork values of mass=4000
> > > and moment=50 for the 4-bladed, 2.29 radius props but I have
> > > little confidence in them.  Does anyone have any idea of
> > > what the typical ball-park figures should be?
> > >
> > > I\\\'m also not specifying a value for the turbine bsfc yet
> > > (eng-power=3200) and it looks as though all the fuel is
> > > gulped down in < 1 sec.  Here too, does anyone have any idea
> > > of ball-park figures I could try using?
> > >
> > >
> > >From the comments in p51d.xml:
> >
> > <!-- moment calculated using formula submitted by Donald
> > Simon: MOI = # of Blades * (8.2*(10^-5))*(D^5), slug-ft^2 then
> > converted to kg-m^2 and finally square root to kg-m for torque
> > value
> > -->
> >
> > D is the diameter in feet, to get MOI in slug-ft^2.  My calc
> > is 239 slug-ft^2 for
> > 4 blade, 2.29 radius.  The mass is the weight of the engine
> > plus a whatever you
> > think a prop that big would weight...probably 200+lb.  If you
> > know the make and
> > model of the engine then you could probably find it.
> >
> > Best,
> >
> > Jim
> 
> Ta for that.  I\'ve just found out that a later variant of the 
> Bristol Proteus was used in the Brittania so I might be able to 
> get some usable data by researching that a/c.
> 
> LeeE
> 

You know something does not look right about that "comment".  Here is a

converter link:
http://online.unitconverterpro.com/moment_of_inertia.html

When I use this things do not come out right...or at least the way the
p51d 
is configured.   No where have I been able to find a referece to kg-m
being 
as an moi, but that is what the YASim doc asks for.

Maybe Andy will see this and clarify.

Best,

Jim Wilson




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