One-Handed cutaways on spinners

[riggerpaul 1]

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Both the reserve pilot chute and the Skyhook pull on the reserve bridle.

Yes, but from which direction?

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How does the Skyhook ensure that the risers are even and parallel when the reserve pilot chute does not?

I'd explain it, but Bill Booth does a much better job. In particular, read the second paragraph of his post. Sure he has a vested interest in the skyhook, but the physics as described do make some sense.

Sorry, I am not sold, Bill's explanation notwithstanding.

Once the risers release, there is no longer any radial acceleration, and you will travel in a straight line.

Yes, you might initially be traveling sideways, but nothing is going to align you any better until you get some tension on the reserve suspension lines.

The Skyhook itself isn't going to straighten you out, since it cannot really exert any significant force on you. The lines are still playing out of the freebag and since the line pouch on the freebag offers virtually no resistance, there is nearly no tension on the lines while they play out of the freebag. Until you reach line stretch, and the bag strips off the canopy, there isn't any force that will align you any different from how you started the deployment. Once the bag strips off the canopy, you aren't connected to the Skyhook anymore, so it isn't going to do anything to you after that. No significant tension can be applied to the lines until the canopy itself, which is firmly attached to the lines, puts some tension on them.

Neither a reserve pilot chute nor a Skyhook can get around that simple fact. The lines get no significant tension until the canopy is pulling on them. That's no different with a Skyhook or a conventional reserve pilot chute.

If you were going to be traveling sideways for a reserve pilot chute deployment, you will be traveling exactly the same for the Skyhook deployment. The Skyhook is a giant reserve pilot chute.

I've been in some pretty spinny CF events, and I never had to lose hundreds of feet aligning with the relative wind.

None of this says that a Skyhook is a bad thing. The Skyhook is a fine thing. Get one if you want it.

I am only saying that some of the "science" doesn't seem convincing to me.

[billvon 2,991]

>Better yet, if you have a Skyhook equipped rig, a single action will be
>sufficient since the Skyhook pulls the the reserve pin and the bridle and
>give you a fast opening with your risers staying even or parallel.

No, it doesn't. It will usually be faster, and that may prevent you from spinning as much, but there's nothing in a Skyhook deployment to keep your risers even.

[pchapman 279]

Summary:

I also think that the Skyhook isn't going to magically make the risers get loaded perfectly evenly.

Yet I think it may do a pretty decent job at avoiding excessively asymmetric deployments, especially compared to some alternatives other than taking a good long delay to get stable after a chop.

Details:

As a spinning mal is chopped, the canopy will do one thing, while the jumper will continue on tangentially to the spiral he was in (as Riggerpaul wrote), and the jumper will be rotating with whatever rotational momentum he's already got during the spiral.

There won't necessarily be a perfect line of symmetry along the jumper's body axis, risers, lines, d-bag, bridle, and chopped main.

HOWEVER, because the Skyhook acts in such a short distance, there won't be a lot of time or distance for a jumper to get into a bad body position relative to his reserve. That's especially true compared to taking a short delay delay before reserve activation (without time to get stable), or perhaps to some degree relative to using an RSL.

(And maybe you are in that spinning mal in the first place with main risers completely uneven. How is Skyhook gonna fix that when you chop?)

One data point is the Skyhook chop (after a simulated spinning mal) seen in UPT's video called "2005_Skyhook_History.mov". Stills from the video are combined in my attachment.

On the video, "in general" the reserve activation is "fairly" inline with the jumpers body initially, and the risers appear fairly evenly loaded. Yet when looking closely, one can see that the jumper has some pitching, yawing, and rolling all going on during the whole reserve activation sequence, changing angles of the body relative to the lines, shoulders not always squared off relative to the risers.

[erdnarob 1]

When doing a cut away, the risers are always symmetrically pulled when using a Skyhook because there is a straight line of forces provided by the cut away main parachute, the Skyhook, the bridle, the freebag (still connected to each other until the free bag is released) and the reserve deploying. You can see that well illustrated especially in case of a spinning malfunction on videos. Risers are pulled symmetrically which is way safer for the reserve deployment. I never realized that until I had a seminar (using videos) with Bill Booth at Skydive Expo at DeLand Florida last March 2010.

Now, when not using a Skyhook, things can be different. You rely on the reserve pilot chute for your reserve extraction. This pilot chute is always going straight up while your body can be sideways in case the main is spinning.

I remember a malfunction I had in the 1990's (no Skyhook). I got a line over then release the brakes. Things went really bad with a fast spinning. I cut away and on purpose, waited 2-3 seconds, before pulling my reserve in order to get flat. It seems that my body was still not flat enough since I saw a white square shape on my right side (I was spinning counter clockwise seen from above). That white square shape was my reserve inside the free bag. In that case, no way to have the risers symmetrically pulled. However nothing wrong happened and I got a nice and soft deployment. It was my first square reserve ride.

Learn from others mistakes, you will never live long enough to make them all.

[diablopilot 2]

I know what the kool aid says, but I assure you it is possible to have asymmetrically loaded risers with a SkyHook System.

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