210-foot freefall

[crwper]

I'm looking at freefalling a 210-foot span. I've made several static line jumps from the object, and would consider myself very current with it. What I would like to do is to gather as much information as I can from a variety of sources, and then do the jump in as informed a way as possible.

What I'm looking for right now is advice on three things:

1) Pilot chute selection
2) Gear preparation
3) Body position and toggle use

The lowest I've freefallen to date was 285 feet, using a v-tec Fox and 48-inch f-111 pilot chute and using a Reactor 4 container. In addition, I've made several jumps in the 300-foot range going stowed with a 40-inch zero-p pilot chute. I was surprised at how little difference the smaller pilot chute size made, and that's spurred some questions in my mind about whether the benefits of a smaller pilot chute might outweigh the disadvantages on a low freefall.

There are objects available to me which are 250 feet and 230 feet, so I can work down to my intended jump.

My first thought was that a 48-inch zero-p pilot chute would be the best thing for a low freefall, but on further reflection I think it's possible that such a big pilot chute will impede the opening of the canopy, even with a multi-equipped Fox. In addition to size, there are considerations of material and design (ie CR's av pilot chutes). I'd like to hear your opinions on pilot chute selection.

As far as gear preparation, it seems obvious that the Velcro should be well-primed, but I'd like to hear any specific suggestions you might have.

As I said, I've made a number of static line jumps from the object, using the full 210 feet and also exiting from lower points. My intention has been to develop my skills with low openings, and also to measure several parameters which I feel might be a factor in the time it takes my canopy to open.

What I've found on static line jumps from 140 feet is that body position and toggle use after opening have a significant impact on the distance I'm able to fly away from the object, which I assume is an indication of the time it took my canopy to open and to reach full flight. So far I've found that a vertical body position with little forward push minimizes the swing resulting from opening shock, which seems to have an impact on opening time. Also, I've found that if I release the toggles but let them up slowly, the canopy is able to achieve full flight sooner than if I had let the toggles up more quickly (which causes the canopy to swing forward). The combination of these two effects can easily half the distance I travel away from the object when jumping from the 140-foot exit point.

What I'm wondering is, do the same body position rules apply to low freefalls? It seems like if I was too vertical, even taking into consideration the design of the shrivel flap, it could increase the force required to peel the Velcro, and therefore increase the length of time the pilot chute is towed behind me. With static line jumps I'm not as concerned about this increase in force, since it is still likely well below the 80-pound break force of the line. (Comments on this?) But with freefall I'm concerned the effect could be much greater. I'd like to hear any experience you've had with this.

Thanks for your help!

Michael

[imported_Tom Aiello]

Hi Michael:

I have several thoughts on low free falls. Some of them are things you've asked for, and some are not. Sadly, I feel the need to subject you to all of them. I have only 20 freefall deployments from 200 feet or less, so remember that these are only my relatively uneducated opinions.

The MOST IMPORTANT thing for low freefall is THE DIRECTION OF PITCH. In my experience, throwing the pilot chute straight up on exit can improve opening altitude by as much as 25'.

>1) Pilot chute selection

I've also wondered if a smaller PC, by opening faster, could improve overall opening altitude. However, I haven't done any research into this, so I'm still using big PC's.

I am leary of using A-V PC's for ultra low freefall, as I fear they may inflate slower. I have no evidence to back this up, but am surmising based on my experience with round parachutes (which open noticeable slower with the apex vent exposed then with the apex vent pinched off).

Generally, I use:

a) ZP pilot chutes: ZP opens much faster than F111. I find F111 unacceptable for low deployment.

b) PC's with no cap or handle: The cap on the top of the PC can cause it to slump sideways on deployment, delaying inflation.

c) PC's with topskin reinforcement: Topskin tapes shape the PC better, helping fight the "non-inflation" problems that can occur when the PC loses shape at the start of inflation.

My preferred PC for ultra-low freefall is a Basic Research 48" PC with no handle or cap. I suspect that a non-vented A-V PC (i.e. shaped, but not vented, with no cap, but with the extra tapes) from CR might be superior.

>2) Gear preparation

I always use pin rigs for low freefall. I just don't want to mess with possible velcro issues. If you are using a velcro rig, I'd recommend heavily priming the velcro. I'd also recommend avoiding the Vision or the Odyssey, which both have burly velcro that might cause a hesitation at zero airspeed (although I generally prefer their velcro for other jumps).

I generally prime my pins, and I replace the closing loops with spectra (more slippery) loops for the low jumps. This often requires a friend at the exit point to keep an eye on my back just prior to exit.

I also open the riser covers (just in case), pin flaps, tuck flaps, and everything else I can.

>3) Body position and toggle use

I pitch upward immediately on launch, and am generally in a 25-45 degree forward position (no more than halfway from stand to belly) on extraction and through deployment. I find this minimizes "swing". Generally, I like to feel that I have fallen directly under the deploying parachute (not forward of it).


>I've found that if I release the toggles but let them up slowly, the canopy is able to achieve full flight sooner.

I absolutely agree. Easing the toggles up is critical. This is especially true if you are so close to the ground that popping them into full drive will surge you into the ground. In that case, you need to flare from midway up.

>If I was too vertical, even taking into consideration the design of the shrivel flap, it could increase the force required to peel the Velcro, and therefore increase the length of time the pilot chute is towed behind me.

As I said above, I'm using pin rigs on the low stuff, so I haven't had to worry about this. I do wonder if deploying from a stand might effect the opening by rotating the pack job on the way out of the tray (due to impact with the top flap), but so far 25-45 degrees seems to work fine.

A few more random thoughts...

I consider secondary inlets (Vtec or PAC valves) to be mandatory for any jump under 200 ft. Those early pioneers who jumped that 180 ft cliff on standard Mojos were all quite deranged, in my opinion.

Also, if the object is tolerant of off-headings, I'd prefer a ZP topskin for faster opening. On an object that isn't as tolerant, I still like the composite topskin. Obviously, you may not have these options

Anyone else have anything on this?


--Tom Aiello
tbaiello@ucdavis.edu

[460]

Tom's covered pretty much anything. I did want to add a couple more things:

1) do not using a locking stow at the tailpocket. your tailgate should be sufficient.

2) i personally have observed the factory pack to open quicker than a propack. think about it... the factory pack does not have the "width reduction fold" that the propack does. the overall # of folds is less. however, i wouldn't necessarily recommend this pack job if you don't have someone show how to do it for base.

base jumping really high objects and really low ones are best in my opinion!

Have fun! - Chris

[d-dog]

First off, my lowest freefalls are in the 300 foot range so I am not qualified to address most issues raised.

However, I have been jumping the new CR vented PCs for a month or so. Specifically, I have eight jumps on their 46 inch vented PC. Statistically, this isn't enough for me to be 100% sure on my conclusions.

Still, here's what my gut tells me in using this vented 46. It DOES delay opening in very low airspeed environments. How much? Not alot, but enough for me to notice - or think I notice. Not enough for me to wince when deploying after 2 second delays from 300 feet. But enough for me to wonder how I'd feel going from 220 or so, for sure.

I've seen video of two of these openings from above. Hard to tell if the video backs up my gut feel on slightly slower opening. Also, my non-vented "big" PC is an old, clapped-out 48 so all variables aren't constant here. Once again, this is my gut.

That said, I really like the vented PCs and am switching over for anything under 46. I will keep one vented and one non-vented 46, and only non-vented 48s and of course the 52 Big Bertha from BR.

Again, my gut from my paltry few jumps on the 46 vented PC is that there is less oscillation - obviously not much of a factor go and throw, but I think I can feel the decrease in oscillation after about 2 seconds delay. I've seen video from above of 3 deployments and there is just nil oscillation with the vented PC.

Anyway, that's my low-timer's, statistically-insignificant, gut-check answer to one question in this (useful and interesting) thread.

Peace,

D-d0g
ddog@wrinko.com

[guest]

Hey Michael just a quick heads up on the JOLY GREEN It's 210 from top and 170 from railing in middle. Was playing there 2 dys ago and tried out my new range finder.Have fun !!!!!

[base 587]

Hey Michel;

Jolly Green's in N. Cali...this one's called Sprout.

We also measured the pillars....140 ft...(guess what Mike and I jumped from last trip HEE HEE)

Sounds like since you're using that dicey breakcord:7 you might be up to a 3 way freefall from the deck next Saturday!....Dave L. will be out to photograph the carnage.

BTW... jumped Yam this morning...EZ hike, low wind.. incredible winter conditions!

Spence

[obi]

>2) i personally have observed the factory pack
>to open quicker than a propack. think about
>it... the factory pack does not have the "width
>reduction fold" that the propack does. the
>overall # of folds is less. however, i wouldn't
>necessarily recommend this pack job if you don't
>have someone show how to do it for base.

Hi Chris, never heard of the factory pack. What is it and where can I learn more about it?

Cya, Obi