Re: YASim Propeller rpm

Jim Wilson <[email protected]>
Newsgroups gmane.games.flightgear.flightmodel
Message-ID <[email protected]>
> From: Lee Elliott
> 
> Hello all,
> 
> I'm trying to work out the right prop rpm figures for the TU-114 
> - the airliner version of the TU-95 'Bear' - and I've arrived at 
> a figure of around 494 rpm for the cruise setting.  I'm also 
> using a value of 958 for the takeoff-rpm, which I calculated at 
> 150 kts and 0 ft.
> 
> This is based on 3.2m radius props and a cruise speed of 475 kts 
> at around 30000 ft.

Off the top of my head...that'd be about 20m circumference, which at 
1000rpm would be 20km per minute.  Since an airliner does about 15km 
per minute.  I think that'd be a bit over the speed of sound...depending 
on altitude.

> Could someone check my maths and confirm that these figures are 
> about right i.e. the prop tips staying sub-sonic?
> 
> While I can get the config to solve with these rpm values the 
> stand alone YASim solver seems to go into a loop if I include 
> the min-rpm & max-rpm tags.  Is this likely to be due to me 
> trying to use impossible numbers in the config or is this a 
> problem within the solver?
> 

Not sure.  Just make sure if you are using a ratio that you scale everything that needs to be.




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