Sometimes, pitot tubes in ACFT become unreliable (with corresponding unreliable airspeed values), as was the case for AF447. Would it be possible to deploy the Ram Air Turbine and gauge a rudimentary airspeed (e.g. stalled or flying) by reading how many kW are being generated?
In other words, could the RAT be used as part of a redundant (or emergency backup) system of measuring airspeed?
Apologies if this seems way out in left field.
I make a few assumptions here: That the FMC would require some reading on the power generated by the RAT and; that there would be a value in kW (or some other unit) able to be displayed, with which the airspeed may be reverse calculated using a rough (or otherwise) relationship of kW generated to airspeed.
Gleaming some equations from windpower, there are some moderately complex formulae relating airspeed to power generated. After factoring in the area of the blades, the temperature and air pressure (which for this matter have corresponding values for altitude etc.), curves may be created which relate power to airflow rate.
If pitot data becomes unreliable, (not addressing PFD clutter in an emergency) would it be possible to refer to curves relating airspeed to kW made by the deployed RAT? Perhaps in the FCOM, AFM or the QRH? At the very least, could this help aircrew identify/confirm a stalled condition?
Thankyou for reading this query. Any ideas?
