Weight and Balance

[randylervold]

Bob,

True confession: re-doing all the performance numbers for the Carbon Cub POH is a project currently in the queue for our engineering department and we expect to get to it this summer. The current POH numbers were put together when the plane was brand new and we did not have as much performance data as we should have -- much extrapolating was done, but always on the conservative side. I'm sure you've discovered by now that your plane will blow away the basic performance numbers.

Regarding the "% power" on the Dynon, there's no EFIS out there where the % power is accurate, there are too many variables needed for an accurate computation that the EFIS does not have access to, and really they would need to load the power chart from the manufacturer which is dyno derived in order to be accurate any way, and that of course is not going to happen. In fact Advanced Flight Systems deactivated the % power feature in their boxes for these reasons. Frankly, for % power, the "rule of 48" is fairly accurate and a reasonable proxy. If anyone is unfamiliar with this method of power computation I'd be happy to post info on it here.

All that said, if you've run enough tanks of fuel through it to know that your k-factor is now properly set then of course you can rely on an accurate fuel flow reading. Also, those tachometers are dead accurate so that data can be relied upon as well.

[turbopilot]

Bob,


All that said, if you've run enough tanks of fuel through it to know that your k-factor is now properly set then of course you can rely on an accurate fuel flow reading. Also, those tachometers are dead accurate so that data can be relied upon as well.

Ok, let's leave % power and POH aside for now. Look at the screen shot. RPM is 2150, FF is 6.2 and altitude is 2,300'. I think FF is right after calibration. Speed is pretty good for 26" tires. So it looks like I may be developing around 50%+ power. Why is RPM low, seems like it should be around 2300 or so. The airplane has a cruise prop, can that be the difference?