Releases

[Tad Eareckson]

It's .MOV

I may need to get to a different machine and connection before I can watch this.

May we say that 50% is even distributed on pilot and glider only when the upper anchor point is positioned so that the glider tows at trim... and aft this point the distribution change ?

First we need to define what's pilot and what's glider. Let's say that the pilot stops where the suspension exits the pod (over his back) and the glider is everything else.

The distribution will ALWAYS be split evenly in half but as the anchor point moves back on the keel to the hang point and then down the suspension the glider will feel and behave more like one point.

I would like to help pilot to discover AT with their own glider without to test each anchor point.

Go to:

http://www.willswing.com/articles/ArticleList.asp#AerotowRelease

They give trim points for all their gliders.

You should be able to trim comparable gliders (from other manufacturers) at comparable positions on the keel relative to the hang point.

It's a lot safer to be too far back than too far forward and - when in doubt - you can never get in too much trouble going to the hang point or a couple of inches fore.

As I didn't test it for me, what kind of help can we expect by anchoring on the carabiner...

When we first aerotowed in the early/mid Eighties the Cosmos was fast and the gliders were slow and EVERYBODY towed one point - not fun but doable.

When we first towed behind the Dragonfly in 1991 EVERYBODY towed two point and anchored to the carabiner.

You may have some slower gliders and people getting tired of holding the bar back but there's nothing stopping them from releasing (except maybe / probably the Lookout Release), resetting the trim, and giving it another shot.
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2022/03/29 12:00:00 UTC

http://www.willswing.com/aerotow-release-attachment-points-for-wills-wing-gliders/
Aerotow Release Attachment Points for Wills Wing Gliders - Wills Wing

[deltaman]

The distribution will ALWAYS be split evenly in half but as the anchor point moves back on the keel to the hang point and then down the suspension the glider will feel and behave more like one point.

Sorry, I should have missed something:
A one point AT is 100% traction (and power to control) on the pilot
A two point is said as a 50/50, and then for the pilot by weighing half allow him to minimize the consequences of overcontrolling.
If that's correct, what are differences by moving the anchor on that point only (not the trim issue). I don't understand how it could be still 50/50 on the carabiner and feel like one point..

[Tad Eareckson]

A one point AT is 100% traction (and power to control) on the pilot

Yes and no.

WITHIN THE RANGE THE PILOT CAN CONTROL THE PITCH (speed) he will have more control authority because his effective weight is more (as it would be if he had ballasted his harness.

However he has thrown away a lot of the top end of that speed range and speed is A LOT more of an issue in control authority than weight is so - in the big picture - he finishes a distant second (and in at least one instance I know of he finishes dead).

...and then for the pilot by weighing half...

Half of the tow tension more than he would in free flight...

...allow him to minimize the consequences of overcontrolling.

Just because he CAN overcontrol doesn't mean he MUST. This is only going to be an issue for someone before he has acclimated to the glider's responsiveness.

...what are differences by moving the anchor on that point only...

In two point with the anchor point on the keel the pilot "weighs" what he does in free flight plus half the tow force.

Well, that's not really right. He weighs the resultant of the downward force vector exerted by gravity and the forward vector he's feeling as a consequence of the tow tension being routed through him. But let's just keep saying it wrong but easy.

That apparent weight stays the same as the anchor point moves aft on the keel back to the hang point.

Once the anchor point starts moving down the suspension the pilot will be fighting a portion of the tow tension and using it for control authority.

When the anchor point is two inches below the keel the difference will be pretty much undetectable.

When the anchor point is:
- at the carabiner it won't
- two inches over the pilot's back he's towing one point

One thing that helps understand what's going on with two versus one point towing...

Stand alongside the runway and watch somebody coming off the cart towing pilot and carabiner. There's a fairly impressive angle formed at the carabiner between the harness and glider suspension. With the glider flying to the left it looks something like:

/
|
|

(I'll keep my eyes open for a photo.)

Think about that in terms of force distribution and trim position.
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2022/03/29 12:30:00 UTC

http://www.youtube.com/watch?v=1Ui8m0J4do8

27-2215
http://c1.staticflickr.com/1/964/41280641665_fcaf1da360_o.png


And note the bar position.

[Steve Davy]

Unreal! What's wrong with some of these people?

http://www.hanggliding.org/viewtopic.php?t=11497
Aerotow release options?

[Tad Eareckson]

Fetal alcohol syndrome, inbreeding, cult leadership.

[deltaman]

yep, thanks to give us your time.

[deltaman]

tested at 120kg direct load (209kg on the line) required less than 8kg actuation.

[Tad Eareckson]

So the load to actuation ratio is 15 - pretty close to the 16.4 I get for my Remote Barrel primary two point release (leechline lanyard). Excellent.

So, assuming things stay linear which I'd predict they do, for us Yanks a 650 pound towline could be dumped with a 25 pound pull.

Thanks much for the testing and data.

[deltaman]

Tad,
why are your remote barrel (ratio 16.8) less effective than your barrel (20.4) ?

[Tad Eareckson]

That's the Keel Release (two point primary) version of Remote Barrel.

http://www.flickr.com/photos/aerotowrelease/8305996819/


1. The Linkage (which connects to the Screw) has to be routed through the Pulley and thus does not pull straight back - there's an offset. I think that's the big issue.

2. The Screw passes through the leechline Base runs (inside the barrel). The shaft area inside the Barrel is ground smooth but, still, it's not doing anything to improve efficiency.

3. You're pulling in opposition to the Keeper bungee (which holds the mechanism closed until actuation - analogous to the spinnaker shackle's spring loaded latch). (When the conventional shoulder mounted Barrel is loaded the Base is stretched thin and the internal Brake resistance disappears.)

4. The pulley isn't frictionless - although it's probably close enough as to be negligible.