Prepared by: Johnathan Nielsen Dept. of Electrical and Computer Engineering Utah State University

1. ECE 5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Topic: Pitot-Static Sensors Prepared by: Johnathan Nielsen Dept. of Electrical and Computer Engineering Utah State University E: johnathan.nielsen@aggiemail.usu.edu 3/11/2010

2. Outline • Reference list • Further Exploration • Major applications • Background • Basic Principles • Types of Pitot Tubes • Typical Configuration • Measurements • Limitations • Advantages • And many more relevant issues in applications (such as, how to choose, cost information, where to buy etc.) ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

3. Real Life Example http://www.computerweekly.com/blogs/tony_collins/2009/06/in-articles-earlier-this-month.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

4. Reference list • Mechatronics: An Integrated Approach, Clarence W. de Silva, 2005 • http://en.wikipedia.org/wiki/Pitot_tube • http://en.wikipedia.org/wiki/Pitot-static_system • http://www.genebenson.com/Training%20Pvt%20-%20Comm/pitot_static_clip/pitot_static_wrapper.htm • Introduction to Avionics Systems, R.P.G. Collinson, 2003 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

5. Further Exploration • Search for Pitot-Static System instead of Pitot tube. • Another good search phrase is Air Data System it will return air speed systems for all kinds of applications ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

6. Major applications • Air Data Systems for aircraft • Fluid flow rate measurements • Can be used in any ducted system where measuring flow would be impossible for an anemometer ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

7. Background • Pitot tube was invented in the 1700’s by a French Engineer, Henri Pitot • In the 1800’s, it was modified by French scientist Henry Darcy. • This modification is the exact form that is still used to day. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

8. Basic Principles • Pitot-Static Systems work on the principle of pressure gradients. • By measuring pressure differences velocity can be determined. • The Static measurement is used for many other calculations. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

9. Types of Pitot Tubes Simple Pitot will measure the total pressure. Static Source gives the ambient pressure. Pitot Static can measure the difference between both. http://en.wikipedia.org/wiki/File:Pitot_tube_types.svg ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

10. Typical Configuration http://en.wikipedia.org/wiki/File:Faa_pitot_static_system.JPG ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

11. Typical Configuration • With the setup in the previous slide there are a number of different measurements that can be obtained, as shown: • Altitude • Vertical Speed • Calibrated Airspeed • Mach Number • Not all of these are necessary for each application ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

12. Measurements • Airspeed Indicator • Uses both Pitot pressure and Static pressure • The difference in pressures will give an indicated airspeed. • The airspeed can be calibrated to give a better representation of actual airspeed. http://en.wikipedia.org/wiki/File:ASI-operation-FAA.png ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

13. Measurements • Altimeter • Uses Static pressure measurement to calculate the altitude of the aircraft. • Altitude is based on standard air pressure at sea level. http://en.wikipedia.org/wiki/File:Faa_altimeter.JPG ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

14. Measurements • Vertical Airspeed • Uses Static pressure changes to determine rate of change. • Faster changing air pressure result http://en.wikipedia.org/wiki/File:Faa_vertical_air_speed.JPG ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

15. Limitations • It is possible for the tubes to get blocked which would either skew the measurements or result in no measurements at all. • Density of the air/fluid can change which would affect the instrumentation. • Compensation for the density change is discussed in the book by R.P.G. Collinson from the reference list. • This type of compensation is used in commercial aircraft ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

16. Limitations • Position Errors • The changing angle of attack of the aircraft can lead to varying readings. • The readings are also sensitive to sudden gust of wind or pressure changes • These would also result in inaccurate readings. These limitations are usually momentary and will not cause significant problems with the system. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

17. Advantages • Very simple to implement • Compact size • Sensors are relatively low cost ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

18. Cost • Pitot-Tube • As low as: $4.00 • Up to $184.95 • Airspeed sensor • As low as: $30.00 • Up to $200.00 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

19. Cheap Reliable Pitot-Static System Differential Pressure Sensor for Airspeed Absolute Pressure Sensor for Altitude www.eagletreesystems.com ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

20. Conclusion • Pitot-Static Systems have been around for a long time. • The are very reliable in measureing fluid flow and are widely used for air data systems in all kinds of aircraft • They are easy to make and also inexpensive to buy and therefore easy to implement. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators