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Re: payout

PostPosted: Sun Nov 13, 2016 6:21 am
by SamKellner

That sounds like some good ideas.

Junk Yard Parts?

PostPosted: Sat Dec 09, 2017 3:24 pm
by Bob Kuczewski
I just had a long chat with one of my hang gliding friends, and he described an idea he had for a payout system using a MacPherson strut assembly with the hub, wheel, and brake already assembled and ready to bolt to a truck bed. He also described using a windshield wiper assembly as the "level winder" for retrieval.

Has anyone seen those kinds of components used in towing?

Re: payout

PostPosted: Sat Dec 09, 2017 9:54 pm
by Bill Cummings
No but I would sure like to see a YouTube video with one.

Re: payout

PostPosted: Fri Jan 11, 2019 4:11 pm
by Bill Cummings

Without a doubt there is a left crosswind. (Wind sock at 0:09 showing 35 to 45 degrees.)
On the front truck rack the ribbon is showing left crosswind. (Visible to the right of the carabiner.)
After the glider leaves the truck the keel no longer lines up with the tow road. (Left Crosswind.)
The pilot tries to maintain position behind the truck and over the tow road.
The pilot should have allowed the glider to drift to the right side of the tow road.
The pilot needs to be down wind of the truck not behind it due to the crosswind.
All the crabbing that the pilot did should have always been to the right side/down wind of the road.
The pilot crabs too much and has the glider on the left side/up wind side of the road. (Wrong side.)
As the glider gains altitude above the field the wind speed will be greater.
In this greater wind speed and due to elasticity in the tow line and inertia involved to speed up the payout drum tension will increase momentarily.
This (extra momentary tension.) will narrow the, Sweet Spot, where the pilot should be.
The Sweet Spot will be found down wind of the tow vehicle and not over the road. (And certainly not left/up wind of the tow road.)
With a low tension climb the Sweet Spot will be broad left to right.
With a high tension climb the Sweet Spot will be narrow.
While holding the glider behind the tow truck while towing in a crosswind any increase in line tension will move the lockout boundary to the glider. In this case toward the left wing tip. The glider will then lockout to the left.
On final, note the keel is still aiming left of the corn rows still proving a left crosswind.
Flip-Flops are not the best option for a foot landing.
Tow line recovery parachutes can blossom if tension is lost and the pilot can overtake the chute and get tangled up with it.

Re: payout

PostPosted: Fri Jan 18, 2019 8:15 pm
by Bill Cummings
On the above video there is nothing unsafe about a platform launch with a 40 degree crosswind to the tow road at the wind speed indicated by the wind sock.
Crosswind launches from a platform launch (PL) are much safer than foot launch (FL) with a crosswind.
It has everything to do with the relative wind direction when doing a platform launch.

For example, if there is a 10 mph, 40 degree, left crosswind while doing a platform launch by the time the vehicle is doing 10 mph (On the vehicle's speedometer.) the relative crosswind will be only 20 degrees left crosswind at just a little under 20 miles per hour total airspeed (For the hang glider.)
The good news is, you will be speeding up the vehicle about another 10 miles per hour more to have enough airspeed for a safe launch. This will further decrease the relative angle of the crosswind. The ribbon on the front of the platform vehicle will be indicating hardly any crosswind at all.

When you add to the fact that you will be well above stall speed before you commit to launch (Usually not the case while foot launching.) you should be able to see that when it comes to the two concerns of crosswind and getting above stall speed for launching PL is a lower risk than FL.
If you should stall a tip after lift off from PL you also won't have a cliff face to avoid.
After lift off from PL in a crosswind allow the glider to drift to the downwind side of the tow road. Crab parallel to the road on the downwind side. The only time you want to be straight behind the tow vehicle is when the wind is lined up with the road.

Re: payout

PostPosted: Sat Jan 19, 2019 9:24 pm
by Bill Cummings
Torturing the readers with even more nitpicking concerning crosswind platform launching -- so buckle up and no eye rolling.
Elsewhere, somewhere, I forgot where, I posted this idea at the US Hawks.
Background: I cut the top portion off of my boat's water ski tow post. Then I had a friend modify the top of the tow post so that it would plug back into the top of the water ski tow post and be fastened with a bolt. Now I would be able to use the tow post for water skiing as usual or plug in a "T" bar shaped launching yoke that held the base tube (Control Bar.) of my hang glider.
With time the bolt holes in the tow post took on an oval shape due to the twisting of the glider when the boat would change course (direction).
This allowed the keel tube of the hang glider to swing several degrees left or right of the boat's keel alignment. After we had installed a vertical stabilizer to the keel of the hang glider we then noticed that the glider would weathervane. In other words the glider would nose into the relative wind direction to the extent the worn tow post bolt holes would allow.

What was happening here, in the event the boat wasn't aligned perfectly into the wind, the tail fin on the glider would correct for the boat's misalignment with the wind direction.

It is much easier to align a boat into the prevailing wind than it is to align a land (PL) vehicle on a tow road or airstrip into the prevailing wind.

If I were to build a new Platform Launch on a land vehicle my thinking is that the safest way to do it would be to have the glider sitting on a pivot pole with adjustable limits. Combining this with the use of a tail fin on the keel tube of the hang glider we would be even closer to perfection than is currently in use. (January 2019)

The release near the nose of our glider was hooked to a rope that ran to the bow eye on the boat. When the release was activated by the boat driver, at the command of the pilot, the release and 8 to 9 feet of rope would drop to the floor (deck) of the boat.
This long rope allowed the nose of the glider swing left and right when the tail fin made the glider weathervane.

Having the glider weathervane before launch would eliminate the glider yawing immediately after lift off.

Re: payout

PostPosted: Sun Jan 20, 2019 4:01 pm
by Bob Kuczewski
On Feb 10, 2013, SamKellner wrote:

I just clicked on the video that started this topic and it appears that it's no longer available at YouTube.

I know this is off topic, but I find it disgusting that information - in the "information age" - is being so commonly shredded.

Sorry for the interruption.