PPRuNe Forums - Question about CRJ700

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Question about CRJ700

Hi all,

I fly (as a passenger) between LYS and MUC quite often with Lufthansa. Typically the AC is either a CRJ700 or CRJ900. I have noticed something rather strange on the 700.

On the tips of the wings where they stick up, there are some kind of probes (I assume they are probes anyway) on the trailing edge of both wing tips. On the port wing, the top probe starts to oscillate in a circular fashion close to and at cruising speed/altitude.

On the starboard wing this does not occur even though similar probes are present.

On the CRJ900 this doesn't happen.

What are these probes for? (if they are indeed probes)
and why would one of them vibrate like this - wouldn't this affect any measurements coming from it?

Sorry if this is a stupid question, but I have no idea who to ask about this...

Thanks all

Rich

If there was some sort of loose fixture here it may start to oscilate in a circular fashion due to the tip vortices generated by a wing. Why it is there and if it is important I do not know!

Quote:

On the tips of the wings where they stick up, there are some kind of probes

These are known as "Static Whips". They are [almost] the equivilent of a Lightning Conductor. As for the occilations, probably due to local airflow/vorticies.
watp,iktch

Ah yes - the "static whip" sounds like a good description - I hadn't thought of that. I guess oscillations of this kind would not affect their purpose.

What is interesting is that this oscilates on every CRJ700 I have been on (assuming that it's not the same one every time....) and only on the left wing.

Nothing abnormal there then?

Thanks for explanation :)

I thought that they were static WICKS not WHIPS.