Jump to content

Tug Tow release


Recommended Posts

I use this on my Wot-4 XL. 

Homemade from some 6mm ply and a spare U/C saddle clamp. 

The tow line is attached to the keyring. 

The assembly is held in place by the wing bolts. 

 

It's simple, it's tried and tested and it works. 

It would only be needed if the glider gets into difficulties. You don't want the tug to  be dragged down with the glider so a flick of the switch and you're free.... large.IMG_20220205_130625.jpg.f1e0b451869422be4137d50dd20b70ff.jpg

Edited by Brian Cooper
Link to comment
Share on other sites

Does it work under load with the small servo? In the full size world, several tug pilots were unable - or found it extremely difficult - to operate a release under load - a kiting glider can exert a lot of force.  In one case at my club, the rope broke at literally the last moment and the Chipmunk was severely damaged as it pancaked but happily the tug pilot survived virtually unscathed.  It's quite likely not all were so lucky.

 

Releases were redesigned with over-centre locks to make release easier in an emergency - coupled with weak links, safety was certainly improved.

Link to comment
Share on other sites

34 minutes ago, Martin Harris - Moderator said:

Does it work under load with the small servo? In the full size world, several tug pilots were unable - or found it extremely difficult - to operate a release under load - a kiting glider can exert a lot of force.  In one case at my club, the rope broke at literally the last moment and the Chipmunk was severely damaged as it pancaked but happily the tug pilot survived virtually unscathed.  It's quite likely not all were so lucky.

 

Releases were redesigned with over-centre locks to make release easier in an emergency - coupled with weak links, safety was certainly improved.

 

It was tested by towing and releasing a glider which weighed about 10 pounds. It worked every time. 

It would be easy to fit a bigger servo for greater peace of mind. 

Edited by Brian Cooper
Link to comment
Share on other sites

Sounds good. The sort of situation I was thinking of was with the glider way out of position pulling very hard on the release bar.

 

It was a very serious situation on full size as the attachment point was below the rudder and a glider could easily overpower the tug’s elevator if it got too high - especially with a belly hook, putting the tug into the ground very quickly.  I lost a good friend to this. 

  • Like 1
Link to comment
Share on other sites

The other area the tow release needs to work is on take off, I've been at a couple of aerotows were a glider has got hung up on take off, i.e. caught a wing tip in and swung round, the glider pilot hasn't been quick enough with his release and the tug pilot has had to rely on his release to allow the tug to get safely away

 

While there's not much load on the release under normal operation where you throttle back before releasing to take the tension off, it has to work under the extreme conditions when you really need it.

  • Like 1
Link to comment
Share on other sites

Normal aeroplane - you need the best quality and torque servo on elevator.

A tug needs the highest torque servo on the tow release and same or next best on elevator. 

The rudder on a tug may also need a grunty servo if the tow line can pull against it but you still need the rudder to work against the side load of a glider on tow.

Applies to the glider as well.  ( strongest servo on aerotow release).

Oh, and don't be tempted to use a retract servo - they are too slow to release after you have flicked the switch - don't ask how I know that!

  • Like 1
Link to comment
Share on other sites

This quickly knocked up diagrammatic representation of the sort of thing I was thinking of would remove all holding load from a servo, while allowing release under any amount of tension with minimal servo torque required:

 

Capture.JPG.9da0f1644b4bd8b457014daf6a15f0ae.JPG

Moving components shown in green for towing positions and red after emergency release operation.

First pivot from servo allowed to sit slightly over centre in towing position.  Floating pivots shown in black.

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...