low bridge

[guest]

115 foot over very soft ground. 5 jumps so far by 3 different jumpers. All PCA.

4 good openings with very short canopy rides and rear-riser landings.

1 bottom skin only inflation and sink into the mud.

Is this the sort of thing to expect regularly when jumping low objects like this?

Is a tailgate pointless at this height and just slowing things down? - 2 jumps have used tailgate so far and 1 was the nasty one.

Other than good life insurance do people have any suggestions?

[guest]

find a bigger bridge?

[guest]

Do you guys jump bare foot so your shoes don't get dirty in that mud? Just a suggestion.

[imported_Tom Aiello]

>Is this the sort of thing to expect regularly
>when jumping low objects like this?

Yes. You are approaching the point where the natural variability of the complex parachute system (that's a long way of saying "Black Death") will begin to govern your altitude equation. In other words, at 115 feet, Black Death might just rise up and strike you down. You are taking your life into your own hands.

>Is a tailgate pointless at this height and just
>slowing things down? - 2 jumps have used
>tailgate so far and 1 was the nasty one.

No! This is a major misconception. Appropriate reefing will actually encourage a faster inflation, not a slower one. The tailgate generally discourages line overs by promoting nose first inflation. Nose first inflation actually provides a faster route from line stretch to full flight than un-reefed (tail first) inflation. In a tail first inflation, the expanding tail can have a collapsing effect on the nose, pinching it off momentarily and slowing inflation.

Also, imagine dealing with a line over from 115 feet. If you manage to react in time (pitching your toggle to avoid being spun in sideways), your canopy will still be diving to recover when you impact. Either way, your going to be lucky to walk away.

On the limited information given, I might hypothesize that your tailgate was closed too tightly for a zero airspeed deployment. I know of three cases in which this occured on PCA deployments, two of which were low enough (like yours) to result in a jumper pounding in under a partially inflated canopy.

On a zero airspeed deployment, when closing the tailgate, my advice is to (a) use no more than two wraps with a standard rubber band, (b) do not use the black BR tailgate rubber bands, (c) do not girth hitch (larkshead) the rubber band to the tailgate. In my opinion, any of these three (or especially all three in combination) could lead to a tailgate hangup. Even if it cleared itself quickly, you would find inflation inhibited enough to create problems at your altitude. Disclaimer: All three of these pieces of advice are in direct contradiction to the manufacturers (BR) instructions for tail gate use. In this case I disagree quite vigorously with the BR instructions ( I believe that CR's technique is much closer to the one I use, though--so I'm not totally alone in recommending this).

>Other than good life insurance do people have
>any suggestions?

At that altitude, you are a grown up taking your life into your own hands. Go forth, and follow your own path. Just make sure your family knows that you made the decision on your own, so they don't try to sue, prosecute or otherwise harass your jumping partners in the event of an accident.

Have fun!

--Tom Aiello
tbaiello@mac.com

[crwper]

The comments below are based on my limited experience on low static line jumps. Take it for what it's worth.

How experienced is the person holding the pilot chute? The skill of this individual could make a very big difference at that altitude. We usually static line these things for consistency. For anything below 100 feet, I'll go to a d-bag. I believe it has all the benefits of a skillfull PCA (Tom can maybe comment better on skillful PCA's), but I believe it's more consistent.

What canopy are you using?

We've been static-lining a 111-footer over solid ground. Ground elevation about 3500 feet ASL. 5 jumps by 2 different jumpers, all v-tec Fox canopies, all using the tailgate in a standard configuration.

2 jumps with a slight headwind caused problems because (as you know) there isn't a lot of forward speed at that altitude. The headwind was enough to drop us straight down, which makes it hard to PLF at the bottom.

The launch seems to be really important on low static line jumps. If you push out, you'll induce a canopy oscillation which can affect your opening and also eats up altitude in a hurry. Try to drop straight off the object.

Also, with the rear riser thing, it's very easy to get on the rear risers too soon, and impede your canopy's inflation. On one of the first jumps from our 111-footer, one jumper basically trashed his canopy and came in moving backward slightly. He was just way too aggressive with the risers.

That's my 2 cents worth...

Michael

[guest]

Both Tom and Michael have given you what I consider to be very sound, solid advice. (nice post Tom!)

My experience in ultra-low jumps is somewhat limited. My lowest freefall was 190ft. 8 static-lines from 170ft. 1 static-line from 140ft. And 2 static-line jumps from 122ft.

Here are my personal preferences:

Like Michael, I prefer static-line because I believe it is more consistent than a human, no matter how skilled they are. If a person releases early from these ridiculously low altitudes, it's curtains.

I always drop straight down (as much as I possibly can given the object).

With my Black Jack, I had plenty of time on the 140ft jump to release my brakes and fly to a nice flared stand-up landing.

On my first jump from 122ft, I used the rear-risers and had an easy, PLF landing.

On my second jump at 122ft, I released the brakes went to half brakes and flared from there and had a pleasant stand-up landing. (The Black Jack is incredible) I do not recommend this from these altitudes because if done incorrectly, you may surge into the ground.

And even more importantly, these are very, very dangerous jumps and I wouldn't recommend them to anyone. I have my own reasons for doing them and it is very much a personal decision.

[Slim]

I want to meet the guy who free falls it!

Luv SLIM

[guest]

thanks for the advice, very useful.

For the record, the canopies were
Mojo - almost brand new
Mojo - old
Decelerator - old
Fox with retrofitted VTEC - newish
Dagger - newish

The dagger had the nasty opening.

[imported_Tom Aiello]

>For the record, the canopies were
>Mojo - almost brand new
>Mojo - old
>Decelerator - old
>Fox with retrofitted VTEC - newish
>Dagger - newish

If you're really worried about it, buy, beg or borrow your friends Vtec FOX, and use that canopy. At 115 feet, the bottom skin inlets are going to help quite a bit.

>The dagger had the nasty opening.

I'm tempted to make some remark about how the Dagger is unsuited for low deployment due to it's shallow angle of attack (which gives it great glide). But, really, one opening is a statistically irrelevant sample. Plus, you guys are jumping a Decelerator (!?), and if I was going to diss one of your canopies, it'd be that one.

--Tom Aiello
tbaiello@mac.com

[crwper]

As Tom remarked... I think if you're serious about jumping objects in low 100's, you should consider using only canopies with bottom skin vents.

A vented canopy will start producing lift faster, and more reliably, than a non-vented canopy.

Also, something I realized on the really low ones, is that a vented canopy makes a way better decelerator. Even if it's not producing lift, the pressure generated throught the bottom skin vents can add a few extra square feet of fabric over your head, instead of an oscillating mess.

Michael

[base587]

You probably won't have to go far Slim, he'll probably be from Australia!

Spence
&-) &-) &-)