Hello. I'm new in this comunity and I'm working on a home made project.
I have read data sheet document for airspeed sensor MPXV7002DP, and its range of temperature operation is from 10ºC to 60ºC.
I will use this sensor in flights with temperature below 10º (perhaps 3, 4 and so on). Then the questions is if I should add something like a pitot heat to elevate the temperature before the air reachs the sensor.
If I should do it, someone have any suggestion about the circuit to do it?
Thanks in advance.
Replies
What are you wishing to use the sensor for? How accurate do you want the pressure reading to be? It is not really the temperature of the air at the pitot that is the issue here. It is the environmental temperature that the sensor experiences that is the problem. The sensor performance is specified by the manufacturer to be within specified tolerance over the indicated temperature. The sensor will still work outside of these temperature, within practical limits ( ie, not at -50deg c, for example) but its output will be out of tolerance. having said that, even within the specified temp range, that sensor will vary by many millibar over that temp range, if no temperature compensation is applied , either electronically, or mathematically, ie, measure the temp of the sensor and provide it with a constant pressure while varying the temp over the desired working range. Apply a 2nd or 3rd order polynomial correction to the data and the output is vastly improved. Unfortunately, it is not perfect, since the curve fit only really applies the best at that pressure or close to it - If you want very good results you need to apply 4 or 5 accurate set pressures, and vary the temp over the working range, and generate a curve fit for all the temp ranges, and then interpolate for the different pressure ranges...
Remember, a 1millibar error is approx 8meters in height.
The air temperature does play a role as well - hot air is less dense, so you should compensate the pressure reading against air temp as well. But the errors from this are dwarfed by the pressure variation errors due to sensor temp change.
Rather get one of the sensors where they have done that for you, and provide you with a calibrated digital output..
Joe
The Nampilot