[reluctantsparrow]

to Any Hawks attending the Otto Meet Tomorrow......make sure and run these ideas past Any Hang gliding manufacturers that show up....who knows? they might turn these ideas into a reality in a very short time or these ideas might spark an idea of their own that is even better.
....sorry I cant make it down for the meet,....RS.

[Bill Cummings]

RS,
My best guess is that the angle arm coming down below the keel tube will put too much of an out of column load on the keel which will bend or kink the keel tube as it restricts the forward movement of the pilot.

I'd guess that a compression shock with a bridle line running from the keel at an angle to the pilot would withstand much more of a load before damaging the keel.

All though it gets too complicated I would think a hinging "T" tube perpendicular to the keel would tend to keep the compression load more in line with the keel.
Think of the T as having a pivot point where the vertical leg meets the horizontal part of the T.
With the --- This explanation is not working --- I can smell your gears grinding from here.
Let me try to attach a picture ---

T pivot. bridle, shock absorber.JPG (31.6 KiB) Viewed 3681 times

[Frank Colver]

I like Chris Price's advice to the assembled members of the Southern California Hang Gliding Association (which later became USHPA): "Always land into the wind standing up". That's simple and straight forward just like: "Buy low, sell high". Why do we always have to complicate things?

Frank

[Bill Cummings]

I like Chris Price's advice to the assembled members of the Southern California Hang Gliding Association (which later became USHPA): "Always land into the wind standing up". That's simple and straight forward just like: "Buy low, sell high". Why do we always have to complicate things?

Frank

Chris had good advice -- but I think I'll leave my wheels on.

[Frank Colver]

Chris had good advice -- but I think I'll leave my wheels on.

Me too!

Example: See my recent Dockweiler video.

Frank

[reluctantsparrow]

RS,
My best guess is that the angle arm coming down below the keel tube will put too much of an out of column load on the keel which will bend or kink the keel tube as it restricts the forward movement of the pilot.
]

Wont know until it is actually tried of course, but you raise a valid area of concern and a potential remedy to address that concern.
However, if the device becomes too complicated....hmmmm.

we need an idea that does not increase drag in regular flight,
We need the device to be an after market bolt on to encourage widespread usage of the device.
We need the device to require no alteration of key structural components of the aircraft.

the rear flying wire/rear landing wire junction is extremely strong and provides a huge amount of columnar support.
the device should attach as close to that junction as possible, to the rear of that junction if it is to remain an aftermarket device.
your drawing fulfills all those parameters except the hinging point on your drawing is farther away from the rear landing wire/rear flying wire junction than I envision and an external shock assembly running to the heartbolt area provides a great deal of drag and complication but your idea has given me another idea.

the downward swing of the stinger could take place with zero or a very small resistance factor beginning when the pilot has pulled in the basetube past the upper abdomen area. the stinger continues to deploy as the pilot continues to pull in (providing no resistance to the pull in) until the basetube is fully stuffed.

so when the glider is fully stuffed there will be a stinger hanging down waiting and ready to provide shock absorption in the event the pilots body swings forward beyond the fully stuffed position but not until then.

this accomplishes two things:
1. the keel is under no pressure as the stinger is lowered into position.
2. At high speed (fully stuffed) the fully deployed, downward angled stinger provides drag and a stabilizing factor in a high speed dive, reducing PIO potential.

[reluctantsparrow]

A stinger that pre-deploys in this manner also accomplishes a third major safety factor.
3. the arm is fully deployed and ready to engage from a position that places the bridle or leash in-line with the keel of the glider before rapid deceleration of the glider takes place, greatly reducing, if not eliminating completely, the pendulam action that swings a pilot up into the keel of the glider.

[Bill Cummings]

A stinger that pre-deploys in this manner also accomplishes a third major safety factor.
3. the arm is fully deployed and ready to engage from a position that places the bridle or leash in-line with the keel of the glider before rapid deceleration of the glider takes place, greatly reducing, if not eliminating completely, the pendulam action that swings a pilot up into the keel of the glider.

Plan B with limitations:
Assuming that pilots that buy topless gliders won't even let a shoulder to shoulder strap pro-tow bridle flap in the wind after releasing from tow;
I see an after market safe splat add on as a much harder sell to pilots in the competition mind set.
If we scrap an idea because it is not universally embraced it will not protect that part of the flying community that flies with king posted gliders.
Plan B is for the segment of the HG pilots flying king posted gliders.

Plan B:
1. How about a 3/16" hinge pin located one and one half times the diameter of the keel tube rearward of the rear cables anchor point.
2. Two Aluminum straps, one on each side of the keel-tube.
3. The two Aluminum straps would normally lay along each side of the keel when not deployed.
4. When the pilot swings so far through the control frame the two Aluminum straps will hinge perpendicular to the keel-tube.
5. What keeps the Aluminum straps from rotating beyond the desired limit will be another 3/16" pin, rising up, coming in contact with the rear king-post wire.

[reluctantsparrow]

That is absolutly brilliant Bill! You just opened up LOTs of possibilities !!!!! Your idea as is can be used to predetermine the foreward motion of the pilot.....the resistance is only aplied after the arms swing down into position therefore reducing the upward swing of the pilots body....the upper pin resting against the rear landing wire could be a small bow roller that snuggles the keel when it is not engaged but also provides a nicely curved place for the rear landing wire to snuggle up against as well. the kingpost can now be fitted with a compression device to dial in the amount of resistance and travel allowed.....your idea is an aftermarket bolt on.....plus an after-market shock absorbing kingpost or shock-absorbing device built into the rear landing wire itself....or....it could be built into the front landing wire and the weight of the shock absorbing device would counterbalance the weight of the pivoting device.....the front to rear landing wire would probably need to be beefed up .....a few other details to work out.....but
.... your dual, pivoting arms could be made streamlined to flush up nicely along the keel in regular flight!...the only extra drag would be the leash and a small amount of parasitic drag from the devices.......
And your idea is super simple....Any backyard mechanic could build this in their own garage!!!!! I could mock up a prototype this afternoon this idea is so simple.
I dont like this idea Bill....I LOVE it!!!!

As to WHY we need such a device.....

I like Chris Price's advice to the assembled members of the Southern California Hang Gliding Association (which later became USHPA): "Always land into the wind standing up". That's simple and straight forward just like: "Buy low, sell high". Why do we always have to complicate things?

Frank

We have to complicate things because Chris Prices advice is wishful thinking if such advice is taken to mean we do not need to develope any splat protection. His advice taken to that extreme would not reflect the real world and i doubt his good advice was meant to be taken in this way.
I can produce a body count of personal friends that are now dead or sitting in wheelchairs that resulted from incidents a safe splat device would have prevented.
All the Pilots I am thinking of right now were excellent pilots except one who was never really very good.
some of these crashes were pilot error but most were the result of extreme turbulance coming into an LZ or a last minute wind reversal due to thermal activity nearby....
I need to complicate things because I can not command the wind to not switch on final and I can not flip on a power source to abort my landing if the LZ is a boiling cauldron of turbulance.
Chris Prices advice works perfectly in a world where all factors, including the wind can be perfectly controlled, but I do not live in that world.
A parachute is a complication but we all fly with them.
Wheels are also a complication and Although i do fly without wheels occasionally
I only fly without wheels at the beach where landing conditions are highly consistant....
I do not fly without wheels in turbulant, thermic, cross country conditions.
Wheels, Parachutes, and a safe-splat device are complications I value.
Wheels and Parachutes are also safe splat devices in their own right along with the hang glider itself which is our primary splat prevention device. The hang glider itself is a complication to provide splat protection.

reminds me of the eternal optimist who fell off the empire State building without ANY splat protection devices in place.
Each time he fell past an open window he shouted out....so far so good.....
And he wasnt wrong in saying .....so far so good....because he WAS doing pretty good so far......his body WAS still in one piece.....but he was not being too realistic in my opinion.

[ARP]

RS & Bill,

Although the modification proposed may have some merit I think that the extra weight and complexity would make it impracticable. Having looked at the various devices suggested the simplest would be a line from the pilot harness, chest area, to the centre of the control bar. If it was made so that it took up slack as the pilot moved it should not cause any control restriction or snagging. In the event of a sudden nose in on landing the the line would limit the pilot follow through preventing head contact with the glider nose. An added safety feature of having the line attached to the harness would be if the pilot failed to clip in on the keel he/she would still be clipped to the control bar.

The limit line length only needs to be long enough for the pilot to push fully out when in the flare, I guess about 30 inches? Another safety feature of such a limit line would be for weightless situations or dropping of the top of a bodged loop. The pilot would not fall into the wing which usually collapses the airframe.