Aircraft ice protection control system preheat logic
An ice protection system for controlling icing on an aircraft surface includes an OAT sensor configured to provide a signal indicative of an OAT, a LWC detector configured to provide a signal indicative of a LWC, an electrothermal device located on the aircraft surface, and an electronic control system configured to determine a critical temperature (TC) at or below which an anti-icing system will be used to preheat the aircraft surface, supply an electrical power having a calculated power level to the electrothermal device, and calculate the power level as being: zero if OAT>TC and LWC=0, controlled based on OAT and LWC if OAT>TC and LWC>0, controlled based on OAT and LWC if OAT<TC and LWC>0, and controlled based on OAT if OAT<TC and LWC=0.
1. A method of supplying power from an electronic control system to an electrothermal device on an aircraft surface to control icing on the aircraft surface, the method comprising:
determining a critical temperature (TC) at or below which an anti-icing system will be used to preheat the aircraft surface;
sensing an outside air temperature with an outside air temperature (OAT) sensor;
detecting an outside liquid water content (LWC) with an LWC detector;
calculating a power level using the electronic control system; and
supplying electrical power having the calculated power level to the electrothermal device under control of the electronic control system, the calculated power level being:
zero, if:
OAT>TC; and
LWC=0;
controlled based on OAT and LWC, if:
OAT>TC; and
LWC>0;
controlled based on OAT and LWC, if:
OAT≤TC; and
LWC>0; and
controlled based on OAT, if:
OAT≤TC; and
LWC=0.
2. The method of claim 1 , wherein the power level is controlled by controlling a duty cycle of the supplied electrical power.
3. The method of claim 1 , further comprising:
determining a threshold temperature (TT) above which the anti-icing system will not be used; and
calculating zero power level if OAT>TT.
4. The method of claim 3 , wherein TT is about 1.7° C. (35° F.).
5. The method of claim 1 , wherein TC is determined based on testing performed in a wind tunnel test facility.
6. The method of claim 1 , wherein TC is determined based on an available power budget.
7. The method of claim 1 , wherein the surface is on a rotary blade.
8. The method of claim 1 , wherein:
the OAT sensor is mounted remotely from the electrothermal device; and
the LWC detector is mounted remotely from the electrothermal device.
9. The method of claim 1 , further comprising repeatedly performing the method.
10. The method of claim 9 , further comprising performing the method in response to a stepping signal.
11. An ice protection system for controlling icing on an aircraft surface, comprising:
an outside air temperature (OAT) sensor, configured to provide a signal indicative of an OAT;
a liquid water content (LWC) detector, configured to provide a signal indicative of a LWC;
an electrothermal device, disposed on the aircraft surface;
an electronic control system, configured to:
determine a critical temperature (TC) at or below which an anti-icing system will be used to preheat the aircraft surface; and
supply an electrical power having a calculated power level to the electrothermal device, the calculated power level being:
zero, if:
OAT>TC; and
LWC=0;
controlled based on OAT and LWC, if:
OAT>TC; and
LWC>0;
controlled based on OAT and LWC, if:
OAT≤TC; and
LWC>0; and
controlled based on OAT, if:
OAT≤TC; and
LWC=0.
12. The ice protection system of claim 11 , wherein the power level is controlled by controlling a duty cycle of the supplied electrical power.
13. The ice protection system of claim 11 , wherein the electronic control system is further configured to:
determining a threshold temperature (TT) above which the anti-icing system will not be used; and
calculate zero power level if OAT>TT.
14. The ice protection system of claim 13 , wherein TT is about 1.7° C. (35° F.).
15. The ice protection system of claim 11 , wherein determining TC comprises receiving a value of TC determined from testing performed in a wind tunnel test facility.
16. The ice protection system of claim 11 , wherein TC is determined based on an available power budget.
17. The ice protection system of claim 11 , wherein the surface is on a rotary blade.
18. The ice protection system of claim 11 , wherein:
the OAT sensor is mounted remotely from the electrothermal device; and
the LWC detector is mounted remotely from the electrothermal device.
19. The ice protection system of claim 11 , wherein the electronic control system is configured to repeatedly calculate the power level.
20. The ice protection system of claim 19 , wherein the electronic control system is configured to repeatedly calculate the power level in response to a stepping signal.