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Glidingstuff 4 sale

OSRC Stuff 4 sale

This below from Dr Ludek Smolik who makes a range of Total energy probes at very reasonable prices. He explains his yaw free probes. Details and prices are in the chart below. I am getting an order together for New Zealand to save freight and they will arrive in a container about the end of October. So Contact me if you would to get one included.

Hallo Paul,

To your questions according the use of the probes with different varios. I personally have experiences only with the cambridge 302 vario. Here the yaw-free probe works very well. That means you can slip and the reading stays at level which indicates the current change in height. The maximum yaw-angle is approx. +/- 30° . But this is not surprising, nobody will test or use the probe for the sideslip :-). Much more important is the rotatability of the probe for turbulences in the thermal or for the intended yaw in the thermal . But such improvement is hard to meassure due to the lack of direct comparison. So, the argument is the following: if the probe is working perfectly during the slip it will also work in the thermal better then a standard immovable probe. The question whether this is better for the pilot is perhaps a different task and depends on the pilot. I have built something like 10 yaw-free probes and I have received only positive comments about it. Reinhard Schramme will be using it during the Hahnweide Grand Prix.

Some words to the difference between 1-, 2-, and 3 way probes if we are talking about the yaw-free probe.
It turns out that the most sensitive pressure for the yaw is the static pressure. The dynamic pressure is much less sensitive and the TE-pressure as well. If you look at the "negative pressure" behind the the TE-pin as a function of the azimut angle you will find a plateau of aprox. -1,1 x dynamik pressure . This plateau is very significant till +/- 50° around the 180° point (the stagnation point is at 0°) .
The perfect probe should have -1.0 but this coefficint depends on the Reynold number. For soaring velocities and dimensions of typically 1 cm the Re is around 10**5 and the constant is -1.1 In other words the TE-pressure is not very sensitive for yaw. In contrast to this static pressure is very sensitive to yaw, this is clear because each yaw results in a small contribution of dynamic pressure to the static pressure.

Summa summarum , the optimum seems to be the 2-way probe. 1-way is suboptimal .. and 3-way may be to excessive .. or something for real soaring purists :-)) .

Ludek

The Length of each probe is optional up to 1 meter and can be suited to individual requirements. Normal length is 900 mm.

All prices below are in Euros and do not include any freight or local taxes. Contact Dr Ludek Smolik direct at probes@glidingstuff.co.nz with any questions and orders.

Orders should include Length, type of probe and adaptor. Check your Gliders maintenance manual. Newer gliders will have a description like this.

Above is standard on a DG 1000. Optional for a DG 800/808 so check.

A small .jpeg with dimensions would be safe if you are just replacing an existing probe. Especially the multi probes.