GB2271190A

GB2271190A - Aviation icing advisor

Info

Publication number: GB2271190A
Application number: GB9220884A
Authority: GB
Inventors: Tristan John Gadsby
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-10-05
Filing date: 1992-10-05
Publication date: 1994-04-06
Anticipated expiration: 2012-10-05
Also published as: GB2271190B; GB9220884D0

Abstract

An aviation icing advisor which senses temperature and humidity, and through processing of these signals gives an output proportional to the risk of ice occurring, eg. for carburettor icing purposes. This analogue output can then be displayed or converted to a digital signal and then displayed on a digital display, or the output can provide a warning or trigger preventative measures when the risk of icing is high. <IMAGE>

Description

AVIATION DICING ADVISOR This invention relates to a device which advises when icing is likely to occur in aviation.

Icing is the cause of many aviation accidents both in general and commercial aviation. Most automated icing prevention systems available only act when ice has formed, and are very expensive. This invention provides an inexpensive solution to advise before icing occurs, so avoiding or preventative action can be taken ahead of time.

The initial application envisaged is for the particularly difficult problem of carburettor icing, which is the cause of a large number of general aviation accidents especially with less experienced pilots.

The present invention provides for the sensing of temperature and humidity, and processes the resulting signals to asses the probability of icing occurring. Calibration of the device is used to ensure accurate prediction in specific applications eg. Carburettor Ice.

The invention will now be described by way of example with reference to the accompanying drawings: Figure 1 shows a block diagram of the basic system.

Figure 2A shows the conditions in which icing occurs which is taken from the CAA "Safety Sense" leaflet on Winter Flying and Carburettor Icing.

The response of the system is designed to meet this graph, using two variables (Temperature and Humidity) to specify any point on the graph.

Figure 2B shows an interpretation of the response graph giving the risk of icing due to temperature.

Figure 2C shows an interpretation of the response graph giving the risk of icing due to humidity.

Figure 3 shows the amplifier complex for the system.

The following is a brief description of the system, and it's operation, with particular reference to the case of carburettor icing.

The system processes signals from the respective transducers of voltage proportional to temperature, and voltage proportional to humidity, with a series of amplifiers shown in figure 3, which the next paragraphs refer to: Section 1 compares the input voltage due to temperature with the voltage given by the transducer when the risk of icing due to temperature is at a peak (shown by figure 2B) and gives a difference between these signals.

Section 2 then converts all negative components of the output signal from section 1 into a positive equivalent.

Section 3 then compares the all positive output of section 2 with a greater voltage having the effect of inverting the characteristics, to give the maximum output when the risk due to temperature is at a peak (the output voltage therefore complies with figure 2H, the peak voltage being at 5 C for the carburettor icing application).

Section 4 which is an inverting summing amplifier adds the output from the temperature processing (sections 1-3) to the signal from the humidity transducer whose response matches that approx. of figure 2C, which produces an increasing voltage as humidity increases, as the higher the humidity the greater the risk of icing. As these signals do not have the same peak values and ranges, the input resistors to section 4 can be varied to proportion the risk due to temperature and humidity components. As the output from section 4 is negative, section 5 inverts this, and also adjusts the peak output signal.

This output gives an increasing output voltage with an increasing risk of ice occurring.

The output can now be sent to an analogue display, or to a comparitor to trigger off preventative measures when the risk of ice climbs above a specified level.

The output can also be converted to a digital signal using an Analogue to Digital Converter, the output of which can be sent to a digital display (giving a percentage chance if the peak output from the amplifiers gives a value of 100 at the output from the Analogue to Digital Converter).

This digital value can then be compared using logic gates to set off a warning, or trigger preventative action when the risk of icing rises above a certain value (eg.70%).

Claims

1. An aviation icing advisor device which senses temperature and humidity conditions and processes them to assesses the possibility of ice occurring.

2. An aviation icing advisor device which uses input temperature and humidity signals, and processes them by way of a circuit as in figure 3, and displaying a measure of the risk of icing on an analogue display.

3. An aviation icing advisor as claimed in claim 2, where the output is digital.

4. An aviation icing advisor as claimed in claim 1 or claim 2 or claim 3, where the output is used as a warning for a pilot.

5. An aviation icing advisor as claimed in claim 1 or claim 2 or claim 3, where the output is used to trigger prevention measures.