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IJskonijn

Descend rate of baglocked canopy vs freebag

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So.... I lost my canopy this week. Doing CRW, opened into a baglock, chopped it at ~13kft. Luckily there was very little wind. I know my exit point, and my freebag was later brought in (found by a local) and I know where they found it. Searching on the ground between those two points yielded no result, but its partially forest area with heavy undergrowth.

Does anyone have experience with the descend rate of a baglocked canopy with open pilot chute (plus some lines trailing, I only had two stows on it) vs an empty freebag (Vector 2 to be specific)? The canopy was a Lightning 160, of which I do not know the weight (guesstimate ~4kg?). Any and all information that can help me more accurately determine the search area would be much appreciated. Maybe some inquisitive mind did some tests on those descend rates in a big empty field?

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I've chased another jumper's baglocked Lightning before. Even with spiraling until I was making myself sick, it landed when I was at ~4000 feet. For most of its descent I could only see it because it had a white pilotchute that stayed inflated the entire time. If the PC hadn't stayed inflated it would have made it to the ground even faster.

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Pilot chute was about 80cm diameter. Weight of a Lightning 160 is estimated at 3.1kg (my carry-on luggage was 12.9kg when I left and 9.8kg when I got back).

A friend of mine has already tried to make a guesstimate of the descend speed of a baglocked canopy, his result is approximately 18m/s (averaged, since terminal velocity decreases with decreasing altitude/increasing density). But feel free to redo the math, it may yield something useful.

What's the descend rate of a freebag+pilot? I've currently guesstimated it at 1000ft/minute, since that's about the same we have under Lightnings and I've kept level with a freebag a few times in the past quite easily. Using that together with the distance between chop and finding yields an average 1.92m/s winds (true, winds were very light that morning). Coupling that to the 18m/s calculated descend rate of the baglocked canopy yields a wind-drift of 422m from 13kft. Much more than the guesstimated 8x to 12x faster earlier in this thread (that gives me 188m and 125m drift respectively).

I lost the canopy at the Parasummer boogie near Pärnu, so if anyone from Estonia (or Latvia) is willing to go search for it based on my data you'd make me very happy. Otherwise I'll likely go myself for a long weekend in a last all-or-nothing attempt.

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Completely unscientific and anecdotal...

I've only ever seen one bag locked canopy go down, and it was "very fast" compared to a free bag or deployed main. Just throwing some random numbers out there... If I found a free bag 1 mile away from the point of the chop in "moderate wind," I'd start looking for the bag lock about .2 or .3 miles away. Or just to be thorough, start looking at the point of chop and work out to where the free bag was.

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Anachronist

If I found a free bag 1 mile away from the point of the chop in "moderate wind," I'd start looking for the bag lock about .2 or .3 miles away. Or just to be thorough, start looking at the point of chop and work out to where the free bag was.



Bingo!

Take along a small backpack with some water in it, and be prepared to hike for a couple of hours, checking all patches of woods, tall grass, etc.

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Thanks! Those results are very similar to what a friend of mine also came up with. That means they should be rooted in known physics.

The biggest uncertainty in guessing the landing area from those numbers is the winds. My freebag was found about 1.5km downwind of my exit point. If I assume 1000ft/minute for freebag descend, I get winds of 1.92m/s (averaged). That would put your results for my main location at 432 to 509 meters downwind of the exit point, much further than I would get from the 8x to 12x faster descend rate than a freebag guess earlier in this thread.

I've already searched the area indicated by your results (for only 2,5 hours, since I had to go to Tallinn to catch my flight home), so I think I'll put more priority in the further upwind numbers (unsearched area), and revisit the already-searched area if nothing shows up further upwind.

If anyone else has any tips/tricks/info, I'd love to hear it. The better I can determine both the likely location and the realistic error in said location, the more chance I have of finding it again when I (or someone else) go back out there.

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