[reluctantsparrow]

nice names Bill....remember the ....second chance....ballistic chute?
this could play off the second chance theme.....call it the...last chance....splat arrestor.....
or, in light of the insurance fiasco....it could be the .... mitigation mitigator......or the title could reflect what it actually does by calling it the.... save our underwear line.. (acronym would be s.o.u.l.)......or, the
necksaver, lifesaver(been done), or.....oh, I like this one...

the showstopper

I mean just think about how boring our LZs would become with no more broken neck...

yeah....I like the showstopper, but I bet its a trademarked name.

[Bill Cummings]

Just jumping ahead and tossing around some ideas for finishing touches for the BTR.

I was thinking that I would get some copper split bolts and fasten an eighth inch or 3/16" rapid link (threaded chain link) to each rear flying wire.

I would use a hollow braid type of rope so that I could make a continuous, no-knot loop for the rear restraint.

When hooking in to the main hang loop I would next put the BTR into each rapid link and thread the two nuts shut then do a hang check.

When storing my harness in the harness bag I would tie a simple knot with the slack in the BTR loop to my harness carabiner so as not to forget to rig it next time.

So to always remember the BTR It will never dangle loose from the mains but either be tied to the carabiner or in the two rapid links.
$how$topper

[reluctantsparrow]

Great ideas that really makes a homemade version of this device within reach of any pilot with about 20 dollars in their pocket as long as they only weigh 60 pounds
going to keep testing this method with greater weight but I think we all know those rear wires or rear nicos are going to fail at some point.
But a new set of rear wires built to spec. A fairly low investment of both time and money.
Heavier rear wires are going to dampen the shock absorption aspect a bit and that is a good thing. The rig as is allows a bit too much shock absorption travel. The pilots head travels a wee bit too far forward.
I think heavier rear wires would solve both problems at the same time.
Reduce pilot forward travel as well as handle the weight loads of actual pilots

[Bill Cummings]

Good point Jim.
As Sandy puts on more weight keep an eye on the keel at the front pulley.

[reluctantsparrow]

Good point Jim.
As Sandy puts on more weight keep an eye on the keel at the front pulley.

good point yourself Bill. I think I will rummage around my aluminum bin and go ahead and sleeve it.
The danger of the forward keel breaking is probably a zip line created problem and not a real life problem?
If the keel breaks in real life I am guessing it will most likely be the portion rear of the kingpost.
One other thing that might fail at some point and need beefed up is the landing wire running front to rear along with the lower rear flying wires. That upper front to rear landing wire is probably a source of stretch as well. Wires do stretch....not much of course, but a long wire like the upper landing wire? yeah, there is probably some stretching going on.
I would like to pinpoint WHERE the stretching is coming from.
This last test shows a pilot traveling WAY forward of the fully stuffed position. We need to find out what part of this set up is allowing all that forward travel, then we can begin to control it.
The existing 1/4 inch aircraft bolt at the rear flying wire/rear landing wire junction will most likely survive just fine but we are going to find out.

WOW! we have some really spectacular crashes to look forward to as Sandy puts on a bit of lard.
I am very happy with both the speed and results of the last test.
I am going to continue testing with only 60 pounds but set up the camera from other points of view.
I really want to get a clear video of those rear wires squeezing together to break Sandys forward speed.
I am going to repeat testing with 60 pounds until consistent test results are confirmed but I am not popping the cork until we are bringing a 220 pound Sandman to a gradual stop without damage...

Thanks for all the good input!.....RS

[brianscharp]

Looks like a fun ride.

Also notice how far forward the pilot is allowed to travel past the fully stuffed position.....this is all shock absorption travel allowed by the rear flying wires pulling together.

Part of it may be coming from the main straps being pulled together, which could prove to be uncomfortable. Consider running the line through a tube to act as a spreader-bar at that point.

[Bill Cummings]

Brian posted while I was typing.
Jim,
If the rear of the keel breaks as a BTR related crash (as the 220 lbs is approached) I think it will happen like my Magic III break happened.
I had the tail tied to the back of the boat as the glider was sitting in the platform launching yoke. The difference with my break was that the tie down rope was pulling at about a 70 to 90 degree angle when the keel failed. The tie down rope was up against the back of the rear wire anchor bolt. The break happened ahead of the anchor bolt by several inches. I don't remember if the area was inner or outer sleeved.

As you might remember the Magic keel was made of frightfully, and doubt inspiring, small diameter tubing. It was a weak point in the glider. I broke it so many times that when I finally retired it - it totaled 8 pieces with kink removed spacers, inner and outer sleeves.

I suspect your keel is more robust and the load on it will be at far less of an angle.

My best guess would be that a stock glider will fail before the 220 hang weight is reached while using the current BTR.

But, just ten pounds dropped from two feet onto the top of my head would do serious neck damage.

Not all whacks will even approach 220 lbs. You so far have demonstrated that 60 lbs from two feet could be removed from the equation. That alone could stave off being paralyzed.

As to the stretch of the BTR. The rear wires coming together will move the limit forward.
The harness mains moving together will move the limit forward.
The mains laying backward will move the limit forward.

[ARP]

Hi RS,

You have been busy with all the testing since my last post....

You have gone back to using the rear wires for the arrest line attachments. This will produce far too much slack as it distorts the wires and will put additional rearwards strain on the A frame which is also being pushed rearwards by the ground contact. There will be a good chance when loaded with a full weight pilot that the A frame will collapse backward as the front wires give way. The attachment at the harness is too high with it located at the base of the main suspension point bringing it closer to the keel which is not what you really want.

Not sure how the internal webbing runs within your harness but I guess the main webbing runs from the shoulders down past the chest and then onto the leg straps. With an attachment sewn in at a point close to the pilots balance point below the chest area and then attached to the A frame the forces on the A frame from the pilots weight will counter the rearward force by pulling forward on the A frame against the rear wires which are in line and can take the load in the intended way up to the rear keel.

As I said before the length of the restraint should be sufficient to allow full pitch control but no more. Using the main harness suspension or rear rigging wires adds too much slack when the loads are applied.

Tony

[reluctantsparrow]

I owe this improvement to a friend who spent the night last night. He is an engineer, approved of the device with one suggestion which I incorporated into this embodiment. Best results yet. My friend, with his many years of engineering work, was not convinced the rear wires will fail if I routed the line in the manner this video depicts.....
I have some other projects I have to get back to. This will be my last post concerning safe splat for a few weeks but its been a lot of fun....RS

[reluctantsparrow]

other project was put on hold (again)....going to be back to testing sooner than anticipated,
going to reinforce the keel, and alter the front hang point dramatically,
my alterations ar going to put less stress on the keel and provide a more definite...WHACK action at the same time.........thanks for all the suggestions....
...if everything looks good after re-testing 60 pounds, will start raising the poundage in 60 pound sandbag increments and post results...RS