civilian jet trailing a small object near Wichita ?

[flyer101flyer]

Hi all. On January 5 in the afternoon near Cheney Lake, Kansas I observed a civilian aircraft flying northbound. Two jet (turbine) engines were mounted on the aft fuselage, T-tail configuration, size appeared consistent with a regional airliner or very large business jet. Winglets were canted out at a relatively shallow angle above horizontal, maybe 45 degrees or so.

A small object was following the aircraft at a distance of about 1/2 to 1 fuselage-length behind the tail. For a split second I thought it was a bird but on further observation, through binoculars, it was obvious that some small object was trailing the aircraft at the end of some sort of wire, hose, or line, which appeared to be connected to the aircraft somewhere in the vicinity of the top rear corner of the vertical stab.

What was this object and what was its purpose? What was the aircraft? Was it possibly some sort of flight test out of Bombardier/ Learjet? I didn't see any test probe on the nose of the aircraft but don't recall whether my viewing angle would have permitted such a thing to be seen. I was basically looking at the aircraft from the rear.

The object was not very steady (as an actual "drogue" ought to have been)-- rather, it erratically orbited around the edge of an imaginary cone with an apex angle of 30 degrees or so, with the apex of the cone being at the point where the line or cord attached to the aircraft. So I don't suppose the device was some some sort of camera.

It appeared that the aircraft's flaps may have been partially down for part of the time that I had the aircraft in view, though I couldn't be sure about that.

Thanks for any info

[tdracer]

Sounds like a trailing cone Pamb sensor. Commonly used during flight testing to provide a highly accurate measurement of the ambient pressure (both to calibrate the primary aircraft sensors and to compensate for distortion of the aircraft sensors during unusual aircraft maneuvers (e.g. extremely high angle of attack during stall testing)

[flyer101flyer]

Thank you very much for the reply.

[john_tullamarine]

Plenty of links on the net as, for instance Aviation video - What is this trailing cone used for? - Lifestyle - Aeronewstv (http://www.aeronewstv.com/en/lifestyle/how-it-works/1218-this-strange-shuttlecock-hanging-off-the-tail.html)

[flyer101flyer]

Thanks for the note John. I did in fact spend a fair bit of time searching the web. For example terms such as "drogue trailing bombardier wichita test". Take a look for yourself, it doesn't come up with much of use on the first few pages, except of course now this thread on PPRuNe. But thanks for the link you shared in your post. S

[victorpapa]

http://farm7.staticflickr.com/6128/6004252516_a693952076.jpg

[john_tullamarine]

One of the main uses for the drogue is developing the PEC data for the AFM/POH. Gets rid of the pitch- and yaw-related undesirable effects on the pressure instrument readings so that the aircraft system can be compared to the closest we can get to undisturbed air.

"drogue trailing bombardier wichita test"

One of the problems with Mr Google is that he has to figure out what it might be that you are looking for ... once you get to suitable terms it works better. Same for me .. often I have to search several times, refining the search parameters on the basis of what the previous search produced ...

[MurphyWasRight]

Often less (specific and words) is more for Google:

"object trailing flight test"

Returns a number of relevant hits on first page, pprune is still first.

'flight test' will match most anything to do with aircraft and is likely ranked by Goggle same as if it had been quoted which allows a match on the 2 words only if together.

Google is also smart enough to parse 'object' to match 'cone' or 'string' in articles that otherwise look relevant. The third ranked article does not contain the word 'object' at all.

Adding 'wichata test' triggered lots of irrelevant news about the union testing management etc.