--- Jim Wilson <[EMAIL PROTECTED]> wrote: > Andy Ross <[EMAIL PROTECTED]> said: > > > Jim Wilson wrote: > > > On the other hand it could be lift. A possible > clue: when I'm having > > > trouble the "mach" reading seems to be way too > high as compared to the > > > KAIS reading just above. Examples: > > > > > > @ 19000ft 419KIAS MACH=0.91 > > > @ 23000ft 344KIAS MACH=0.83 > > > > Those numbers look correct to me. As altitude > increases, the speed of > > sound is decreasing due to the drop in temperature > and the absolute > > speed corresponding to "indicated" airspeed is > increasing due to the > > drop in density. At sea level, mach one is about > 700 KIAS. At the > > tropopause, it's only something like 370. > > Yeah but look at the values again...we're getting > close to tropopause value at > 23000ft. Mach should be well over 600knots at > 23000ft, unless it's _really_ warm.
Be careful here. Andy is, I believe, putting out calibrated airspeed as IAS. Soundspeed is usually calculated in terms of true airspeed, which will be considerably higher CAS at high altitudes and/or mach numbers. > > Best, > > Jim > > _______________________________________________ > Flightgear-devel mailing list > [EMAIL PROTECTED] > http://mail.flightgear.org/mailman/listinfo/flightgear-devel > > __________________________________________________ Do You Yahoo!? Yahoo! - Official partner of 2002 FIFA World Cup http://fifaworldcup.yahoo.com _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
