bobk wrote:Hi Joe,
This is why I'm late today ...
safe_splat1s.gif
I really like this concept BobK, along with another computer image I think you posted of lines running from the rear of the pilots harness to the rear of the keel to arrest foreward swing of the pilot.
I have an idea based on the rear lines to the keel. the primary words there being......rear keel....
I realized this morning that the REar keel offers tremendous potential for a safe splat system that is very simple and I present it here for you guys to pick apart.
The only two positions safe splat is possible I think are the prone position and the suprone because they hang ABOVE the basetube. I can not visualize a safe splat device for a pilot in the supine position.
So, for pilots hanging ABOVE the basetube, lets take a closer look at our totally under utilized rear keel.
What if a singular line was attached from the rear of the pilots harness to a tang about where the rear lower flying wires attach to the the keel.
Now, lets say the rear portion of the keel between the kingpost and the rear wires was designed to slip inside of itself once an impact of a certain poundage was encountered. this could be as simple as an aluminum pop rivet that holds the slip joint together in regular flight but shears and allows, lets say, the smaller rear portion of the keel to slip inside of the larger front portion of the keel.
inside that keel we incorporate an air piston.
As the pilot is swinging foreward with a line attached from the rear of his/her harness to the rear of his/her keel the keel itself has began a foreward journey but is providing resistance much like an airbag does in a car to both slow down the pilots foreward momentum and LIMIT how far foreward the pilots body can ultimately swing.
Problem:
Unfortunately, this is also going to cause the rear flying wire to become slack as the keel slides into itself, allowing the downward pull of the pilots tether to bend the keel downward as it is also pulling the keel foreward....this would eventually cause the keel to fail somewhere around the kingpost/control bar apex area.....not good....so...
instead of a straight tether.....(stay with me)
The tether would run from where the rear flying wires attatch to the rear keel.....down through a pulley in the back of the pilots harness.......then back UP past the keel and past the rear of the sail to attach to the upper rear flying wire around the midway point.....so
as the lower part of the tether is pulling DOWN on the keel....the part of the tether that runs up to the rear flying wire is sucking up all the slack (like the old VG compensator lines did) in the upper rear flying wire and pulling UP on the keel at the same time......
I think this would work to hold the keel in a straight, foreward sliding position....maybe.....I will find out soon.
So I am talking about turning the rear of our keel into an air piston. Kind of like a reverse air bag.
the greatest advantage I see from a crash device like this is it fully utilizes our harnesses as into the restraint system.
Our own harnesses would be our seatbelts so to speak.
this would not add hardly any weight to our gliders.....just an extended sleeve, a couple gaskets, a bit of hydrolic oil inside the air chamber, and a v-bridle.
The air piston coud be made by anyone (whoever comes up with the best, most effective, and reliable design) and sold to hang glider manufacturers to incorporate into any current model of hang glider...
The hook-up would not be complicated either.
Leave the upper part of the v-bridle attatched to the upper rear wire where it is swaged into place.
After the pilot hooks his harness into the glider he/she simply routes the free end of the v-bridle down through the pulley in the back of his/her harness and then clips it into an extra steel tang where the rear flying wires already attach.....done....built in crash protection....go fly....
I see a problem with the prone position however.....
the v-bridle would have to provide enough slack to allow the prone pilot full range of control in the prone position....which is considerable.....it would have to allow the prone pilot to fully stuff the bar and this device might not keep his/her face outa the dirt but it would keep him/her from swinging all the way foreward to the nose of the glider. If this idea was incorporated WITH the swing down anti-whack device pictured above however it would work great for pilots in the prone position.
the pendular load that swings a pilots body up into the keel would shift once the pilots weight engages the v-bridal that runs up to the rear flying wires and runs up to the rear of the keel.
The air piston device could be incorporated to trigger the anti- whack device you illustrated so well in your computor model that swings down from the nose.
Since it is the sudden swinging foreward of the pilots body that shears a small pin that allows the keel to move foreward (about one foot foreward) and engages the air piston...
the same foreward movement of that same keel could release the anti-whack device (also attached to the keel) you have described to swing down into position (spring loaded to swing down then locks into place with small ratchet dogs perhaps)
I think these two ideas are compatable with each other.
For the fun of it I am building a full scale modal I am going to run down a zip line and crash with a couple hundred pounds of sandbags on board.....I am making my air piston from an old bicycle tire hand pump that has the exact same inside/outside specs as the rear keel on an old wills wing super sport frame that is in mothballs in my gargage....this will be fun...
I should have it all done in a couple days and ready to test.
I just need to track down a couple very long ropes for the zip line.....I think I need a rope about 150 feet long and another one about 250 feet long. If anyone has either of those two ropes laying around and wants to mail them to me I would mail them back after the testing.....they need to be strong enough to bear the weight of the sandbags and the hang glider frame I am going to send crashing into the ground at about a 30 degree angle....
I would try to be careful with the ropes but I might be attaching to some trees so I may not be able to keep some pitch from dripping into them somewhere....so....preferably an old, worn out rope you dont care about anymore.
I will video the whole thing and post it here at US hAWKS of course.....cant wait...I just LOVE crashing things into the ground!
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by JoeF » Thu Apr 21, 2016 3:23 pm 
