Kite Strings

http://www.aeros.com.ua/news.php?lang=english&id=252

Aeros wrote:Large deepening in the support will lead to the tail catching the upper points of the support and the glider pitching nose down and crash right after departing from the trolley. We have never discovered this problem because we are using different trolleys where the keel tube of the glider doesn't go deep inside, the deepening for the keel tube is no deeper than the keel tube diameter. Having discovered this potential danger we recommend to pilots that aero towing with tails to use only trolleys where the deepening for the keel tube in the keel support is no bigger than the keel diameter.

http://www.flickr.com/photos/psucvollibre/6257438403/


http://www.flickr.com/photos/psucvollibre/6257964908/


But, I'm quite scared on a bumpy track to see the keel leaving on the side..

1 french tug pilot made that and did'nt test it for yet:

http://www.flickr.com/photos/psucvollibre/6240582010/


Any (good) idea ?

I don't think the keel would come off of the bracket as long as the support is reasonably wide and rigid.

- The basetube is resting in its brackets and as long as it stays there the glider and dolly can't become misaligned.

- If the glider and dolly can't become misaligned the keel can't come off the bracket.

- You have gravity and your grips on the hold downs to keep the basetube in its brackets.

- I've never experienced or heard of a glider becoming misaligned with a dolly during takeoff as long as the wheels aren't castering - and if the wheels are castering you've got big problems anyway.

- The faster you're going the more likely it is that the keel will already have lifted and cleared.

An arrangement like the one in the last photo looks like it would work and could - and SHOULD - be easily tested without hooking a glider to a tug - especially if the tail wing is installed on a scrap of tubing the same diameter as the keel.

P.S. But the shallow wide bracket seems to me like the simpler, cheaper, better solution.

as long as it stays there the glider and dolly can't become misaligned.

?! sometimes it does..

An arrangement like the one in the last photo looks like it would work and could - and SHOULD - be easily tested without hooking a glider to a tug - especially if the tail wing is installed on a scrap of tubing the same diameter as the keel.

http://www.flickr.com/photos/psucvollibre/6240065699/


http://www.flickr.com/photos/psucvollibre/6240065433/

If it does then that bolt on guard is probably the best way to go and I don't have any much better ideas.
A few mediocre thoughts...
Make the:
- basetube brackets as deeply recessed as possible without compromising glider separation
- keel bracket wide and deeper than Aeros recommends but use a guard with it
Set the keel support a little on the low side.
P.S. The costs of any modifications or fixes will be dwarfed if they keep one glider from nosing in because of this issue.

The basetube is resting in its brackets and as long as it stays there the glider and dolly can't become misaligned.

ok thanks, I misunderstood the sentence. I don't know if it can really happen.
I'm ok with you to set the barcket as low as possible with a good manner to take speed on the cart before to leave it.

Consider plywood. MUCH better than particleboard.