Retro fitting a TEk probe

[B Sharp]

There speak non thermal soaring competitors, Messrs Williams and Cole.
Actually the down going sounds are, if anything, more important that the up going sounds. When the vario starts to grind away it is time for a quick 90 degree change of course and get out of there PDQ. If you can stay clear of sink your flight times will increase significantly, even if you don't find much in the way of lift.
It helps if the vario is de-tuned a bit round centre so that it is not constantly beeping either up or down. If it is tuned for lift that will be worth circling in and sink that is double your gliders normal sink rate then you can make informed choices as to whether you circle or run.
Brian.

[SP250]

Retro fitting is a pain.

3 hours just to firtle the long tube down the fin and through a 1/4" hole in the fin base internal rib which the elevator servo extension lead was already part filling.

Moral - build the damn thing in when the model is under construction.
Only got the Thermik XXXL to do now.........

Question for Bernie or Antonia -
Is there a mimimum height up the fin to fit the tek probe, ie above the rear of the fuselage?

John

[Antonia]

Hi John, there is no hard and fast formular for the position that I am aware of, The idea is to raise the probe above any turbulent air flow, but I would aim for at least 3/4 of the way up. Have look at any images of the full size glider, that's a good starting point, as for the Thermik 3/4 of the fin height looks about right.

Hope this helps,

Responding to Brian's comment, I totally agree, down tones are very important in picking your way through the atmosphere, I don't mind the vario in constant motion, that's how I had it in all the full size gliders I flew, as it was mentioned earlier "eyes outside of the cockpit" let the instrument talk to you and guide you, it becomes second nature.....

Antonia

[SP250]

Thanks Antonia
Although that means more pain fitting it, as the inside of the fin is accessible lower down through the servo hatch, higher up the fin where you suggest it is not.
Will have to go in through the fin post behind the rudder, which has a GF skin hinge and is not removable, to get at it.

Cheers John

[Antonia]

Hi John,

From what you've said I imagine the rudder is removable, with the rudder off, make a circular hole in shear web leaving a flange on the sides against the fin skins opposite the where the probe enters the L/E. The probe normally has a fitting that probe slides into with the silicone tube on the rear. Assemble the silicone tube on to the fitting with fine lock wire with a one wrap two tails and twist to clamp down on the tube. Slide it up to the hole put a guide pin through the L/E rotate it and slide forward into the hole, then you can form a fillet of epoxy resin and cotton flox with long wire spatulas through the shear web hole, push the probe into the fitting and set the correct angles and cure. Then the hole can be closed up with a circular patch of the same weave after abrading the hole edge, if you put a bit of peal ply on the repair it will stiffen the patch to hold the shape as it cures.

Once the rudder is replaced it will invisible, from my own experiences you need to have a small piece of silicone tubing on the probe that rolls over the fin fitting to seal the TEK tube.

Hope this explanation makes sense, this is a miniture version of retro fitting TEK tubes to FS gliders.

[SP250]

Antonia

That is exactly what I was thinking to do in terms of fitting the TEK probe and tube.
However, if you read my previous post again, it says that there is a GF skin hinged rudder which is NOT removable, hence the head scratching.
But I think I may have cracked it with key hole surgery again.
Will let you know if successful.

John

[Stuart Ward]

Are there any drawings out there on how to make a TEK tube or is is best to just buy one.

[Antonia]

Hi Stuart ,

I can't find any drawings out there I made mind scale like for my DG & ASH using 2mm OD brass tubing, here's a link that give a bit of design theory http://soaringlab.blogspot.co.uk/2009/1 ... ed_08.html
Hope this helps a bit.

Antonia

[Barry_Cole]

As I read that, it seems that sizes are very critical, and so the chance of it working at scaled down sizes seems remote..

Just my thoughts.

BC

[spike spencer]

Amen !
It's probably like stripes down the bonnet of a Mini-van - it just makes the driver go faster. Nevertheless, if Bling gives you a psychological advantage that helps you believe that you soar better, nobody will criticise you. It improves Scale fidelity anyway.

If you are a Boffin(*) who understands the Physics and Reynolds Numbers of your mini-probe (and have the means of validating and calibrating your installed system) there remains some possibility of Variometer benefit. Otherwise, be content to know that 'Stick Lift' occurs whenever you pull the stick back !
(* Not me - I don't have a brain the size of a planet; I'm just the bloke who gets airborne to bring the numbers back.)

I wait with interest to hear from those who have had (demonstrable competitive advantage) success with a Total Energy Compensation probe in a miniature unmanned sailplane. Do all the GPS course-flyers use them ?