## [DM15] Aeronautical Calculations

Contributed software for the DM10, DM11, DM12, DM15 and DM16 goes here.

Please prefix the subject of your post with the model of the calculator that your program is for.
Walter
Posts: 1472
Joined: Tue May 02, 2017 9:13 am
Location: Close to FRA, Germany

### Re: [DM15] Aeronautical Calculations

grsbanks wrote:
Wed May 20, 2020 3:17 pm
France adopted the metric system in 1795, so that's 225 years ago.

Germany, however, did so in 1872 according to Wikipedia, so that is only 148 years ago... Looks like Walter's clock has a drift of 52/148 years, so that's just over 350000 ppm.
That's just one year after it was united - pretty hard to do it much faster.

France created the metric system AFAIK. But the metric system and the USA, this is an old and really sad story, be it for 225 or 200 or whatever years. Especially since the USA officially declared to join the worldwide standard in the Seventies of last century...
Until they reliably do what they solemnly declare, we've to devote a significant part of calculator functionality to conversions of units being obsolete for 95% of mankind.
DM42 SN: 00041 Beta
WP 43S running on this device

HP-35, HP-45, ..., HP-50, WP 34S, WP 31S, DM16L

AlanW
Posts: 12
Joined: Sat Mar 07, 2020 5:35 pm
Location: UK

### Re: [DM15] Aeronautical Calculations

Guenter wrote:
Wed May 20, 2020 7:24 pm
AlanW wrote:
Tue May 19, 2020 9:18 pm
Conversion between True Airspeed, (TAS), Computed Airspeed (CAS) and Mach Number (M) for a given Altitude in ....
Although CAS is a computed airspeed, CAS denotes "Calibrated Airspeed". BTW TAS is a computed airspeed also.

Günter
I agree and will change 'Computed' to 'Calibrated'

'Computed Air Speed' corrects for position error, which is the error in static pressure measurement due to the shape of the aircraft body causing a pressure change over the static pressure sensor. 'Calibrated Air Speed' additionally takes the non-linearities of the pressure sensors into account. It is 'Calibrated Air Speed' that is displayed to the pilot. BS2G199:1984 is a theoretical calculation and assumes zero position error and zero sensor non-linearity errors, so states the equations in terms of 'Calibrated Air Speed' . I will update the documentation with this and the other two corrections later today (I have to start work in a few minutes).

Many thanks, Alan

AlanW
Posts: 12
Joined: Sat Mar 07, 2020 5:35 pm
Location: UK

### Re: [DM15] Aeronautical Calculations

All errors identified to date have now been corrected in the original post (including the description in the hp15c simulator save file)

Alan