That's a good point. Even though theoretically AOA is a better concept than
airspeed, it may be hard to measure it accurately, especially at cruise speeds
and beyond. Nevertheless, I am still not convinced that this is not possible.
A single instrument calibrated in terms of AOA and airspeed does not seem like
a far-fetched idea.
Fred Fillinger <fillinger@ameritech.net> wrote:
Hi, Andrew --
I wasn't aware that any AOA system provided indications for Vno, Vne,
and Va, much less accurate ones (small AOA at those speeds).
As to an FAR, there's none for homebuilts vis-a-vis the ASI. However,
FAR 23.1323(a) requires that an ASI be a pitot pressure instrument by
inference, and while Part 23 does not apply to a homebuilt, the FAA
can pull out any Reg. or Advisory Circular if needed to define what
airworthiness is.
The further problem is that the FAA inspector will very likely
consider the ASI required by Part 91 as being of the usual sort.
Guvmint employees are just like that (I was one, not FAA, but arguably
same genetic defect).
Regards,
Fred F., A063
Andrew Sarangan wrote:
>
> Hello
>
> I know that the FAR requires an airspeed indicator. My question was whether
an
> AOA indicator can be substituted for it. After all, the AOA gives a more
> accurate measurement of critical airspeeds (Vsl, Vso, Vno, Vne and Va) than
> the conventional airspeed indicator. One can also calibrate the AOA in
terms
> of airspeeds and call it an Airspeed+AOA indicator. However, I do not know
> whether the FAA will accept that as a valid substitute. Does the FAR say
that
> the airspeed must be driven by a pitot-static system?
>
> Thanks!
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