Trailing Cones for RVSM Certification and Flight Test

NOTE: SpaceAge Control offers trailing cones (static cones) for use in RVSM (Reduced Vertical Separation Minimum) certification and general flight testing efforts. To be added to our mailing list for trailing cone developments, send an e-mail message with your complete contact details to cone@spaceagecontrol.com.

Trailing cones were first developed and tested in the 1960's. Much of this early testing work conducted by the Royal Aircraft Establishment, Douglas Aircraft, the FAA, and NASA is used as the basis for RVSM certification efforts today.

Trailing cones give an easy way of calibrating the static pressure error of a pitot-static system. It does this by giving an accurate measurement of the ambient atmospheric pressure (static pressure). The trailing cone system consists of a cone that trails at least one fuselage length behind the aircraft via a high-strength pressure tube. Static pressure is measured forward of the cone by static ports. The cone stabilizes and aligns the ports relative to the freestream airflow. This design eliminates the cost and complexity of retraction mechanisms. This design can also be used on aircraft that cannot use more complex systems.

A general RVSM flight test includes not only the trailing cone system but also a task-specific test system that includes pressure transducers, recording devices (PC), and displays.

A trailing cone is a seemingly simple device. It consists primarily of a cone with holes drilled into it, plastic tube, static ports, and other miscellaneous parts. It might seem that such a device could be put together rather quickly with parts obtained from a local hardware store.

However, designing and producing a trailing cone that will operate without leaks and without failures at Mach 0.9 and -65° C requires a dedicated engineering and manufacturing effort. As the leader in flight test air data products, SpaceAge Control has undertaken the task of developing a trailing cone solution for RVSM certification and general flight testing.

Why are trailing cones so popular in RVSM certification work? Primarily because the FAA and JAA specify them as one of several methods that can be used to perform flight calibrations. The trailing cone method is the most cost-effective and easiest of the methods to perform. Below are excerpts from documents referencing the trailing cone method.

Supporting Documents

• General Article on US RVSM - Domestic RVSM: 1,000-foot spacing between FL 290 and FL 410 is coming. Will you be ready?
• FAA RVSM Site - http://www2.faa.gov/ats/ato/rvsm1.htm
• FAA RVSM Guidance Material - Interim Guidance Material on the Approval Of Operators/Aircraft for RVSM Operations 91-RVSM with Change 1 (30 Jun 99) (doc)
• JAA RVSM Guidance Materials - JAA LEAFLET NO 6: Revision 1 - Guidance Material On The Approval Of Aircraft And Operators For Flight In Airspace Above Flight Level 290 Where A 300M (1,000 Ft) Vertical Separation Minimum Is Applied (PDF)