Power Ratio % Display

[Thomas_Schaad]

Since the EFIS hooked up with the OAT shows Density Altitude and is now connected trough the DSAB to the EMS, I think it would be a great benefit, presenting actual Power Settings in % available.
I think this could make up a smart improvement on the EMS and give at any time a good idea of how much power is available.

Best regards

Thomas

 

[khorton]

Adding a number that claims to be percent power is easy.  The really hard part is making that number accurate.  If you are leaned to mixture for best power (which is almost never the case), the power varies with rpm, MP, altitude, temperature and engine model.  This is workable, except for the fact that there are so many different engine models.  Take a look at the Lycoming O-320 or O-360 Operators Manual, and note the dozens of different power charts.

Most of the time, the mixture is not set for best power.  You need to also consider the fuel flow to get an accurate percent power number, and the calculation is not simple, and it varies with engine model too.

How much error is acceptable? Getting within 10% is probably workable, for a few engine models.  Better accuracy than that requires a lot of work.

Also see http://dynonavionics.com/cgi-bin/yabb2/YaBB.pl?num=1119030796.

 

[Thomas_Schaad]

Hi Kevin,

Talking about the Lycomings you are absolutely right. I was probably a little selfish in thinking, but I generally considered my Rotax 912, although I think, all the FADEC equipped experimental engines would probably give quite accurate indications as well.

I think it still could be a good option for certain engines and configurations. Thanks for giving me the link, I didn't realize it had been discussed before.

Kind regards

Thomas

 

[khorton]

Do you have a power chart for your 912, giving power as a function of rpm, manifold pressure, altitude and temperature?  The last time I looked for one, it didn't look like Rotax had published one.  Hopefully that has changed.