Wanttaja
Sky Savant
The MOSAIC NPRM specifies a maximum clean stall speed of 54 knots Calibrated Airspeed (CAS). CAS is the indicated airspeed corrected for instrument error and the errors due to installation.
This is all well-and-good in the production aircraft world, since determining those errors are part of the testing process. It's a bit awkward in the homebuilt world, since homebuilders generally don't (or can't) perform the specialized testing to determine those errors.
We generally don't care. We note the position on the gauge where the airplane stalls, and that's good enough for us. My Fly Baby stalls at about 55 MPH indicated....but shows a 110 MPH cruise. Don't care about the former, love the latter (even though I don't believe it).
Unfortunately, the MOSAIC requirement (like the Light Sport definition) specified CAS. AC90-89 does refer to "calibrating" the airspeed using GPS, but this method doesn't work as well when trying to note the stall speed.
What I'm wondering is: HOW do the manufacturers compute the instrument and installation errors in their new aircraft?
I'm thinking it takes one of those specialized pitot booms instead of the standard built-in pitot...what Wikipedia calls and Air Data Boom. I'm thinking they also trail a drogue that gives them an independent data source.
So, what do they do?
Ron
This is all well-and-good in the production aircraft world, since determining those errors are part of the testing process. It's a bit awkward in the homebuilt world, since homebuilders generally don't (or can't) perform the specialized testing to determine those errors.
We generally don't care. We note the position on the gauge where the airplane stalls, and that's good enough for us. My Fly Baby stalls at about 55 MPH indicated....but shows a 110 MPH cruise. Don't care about the former, love the latter (even though I don't believe it).
Unfortunately, the MOSAIC requirement (like the Light Sport definition) specified CAS. AC90-89 does refer to "calibrating" the airspeed using GPS, but this method doesn't work as well when trying to note the stall speed.
What I'm wondering is: HOW do the manufacturers compute the instrument and installation errors in their new aircraft?
I'm thinking it takes one of those specialized pitot booms instead of the standard built-in pitot...what Wikipedia calls and Air Data Boom. I'm thinking they also trail a drogue that gives them an independent data source.
So, what do they do?
Ron
