Unvented vs. Vented Canopies

[BASE864]

I've posted a small video on skydivingmovies.com. Click here. The video shows my perspective while jumping an unvented canopy vs. a vented canopy on the same object. If any of you want to see the difference given almost identical conditions - here ya go. I jumped the object with my unvented canopy and actually broke my tailbone on the landing. I then had my canopy vented (VTEC vents & covers) and jumped the same object again. This time the landing was much better.

Canopy: FLiK 322
Object: 230' Span
Deployment method: pilot chute assist (PCA) on both jumps
Brakes: set at factory settings on both jumps
Conditions: Drizzle and light to no wind on both jumps

I am much happier with the vented canopy on lower objects. My opinion is that if you are questioning whether to get vents or not, get them, especially if you are jumping low objects. You can see from the video how much faster the vented canopy is flying and how much longer the flight is because of that.

I'd like to see what others think or hear their thoughts.

[QuickDraw]

That's a great comparison for someone like myself with no experience.


I'm assuming these are typical observations for vented verses non-vented,
but with faster openings are you more likely to have a greater degree of an off-heading opening than with a non vented canopy ?


Thanks for sharing btw.

[ManBird]

I posted this somewhere earlier, but I noticed an enormous difference in my unvented Fox 245 and a vented FLiK 245. Same object (170' S), same exit (PCA side floater), and about the same WL. The other jumper had a small lineover, but had time to clear it, then turn and land into the wind. ~10s, I believe. I had a ~4s canopy ride. Huge, huge difference.

[Mac]

that video shows a great difference in the difference.

I myself used to freefall around the 200ft region with a non-vented canopy and was always happy with it, when I started jumping my vented canopy I swore to myself that I would not take my non vented from below 250ft on freefalls..... the difference was so so noticable............ so much so that my confidence in my new vented canopy ended up with me being injured.

I believe the advent of the vented canopy means either a) people are safer in the lower freefall range or b) people take the vented canopies lower.

My downfall was point (b) - because I was happy taking a non vented freefall around 200ft, when I got my vented canopy I got over confident in the gear and over delayed in the 200ft range............ I have now been out of jumping for 7 months and I am probably not going to get back jumping until next summer.....................

Just dont get over confident in those vents! - you end up feeling like a right twat!

[sabre210]

Hello Base864

It is interesting to see this comparison, but i'm not entirely sure how much we can read into it, mainly because these were PCA's which adds a human variable into the equation. If the person releases the pilot chute even a fraction earlier then the results are pretty much void. The person may believe they kept a grip until full line stretch but how can you measure this for sure.

Also I was led to believe that when it comes to PCA or static lining, the vents will make hardly any difference. This seems to be the case anyway, as i've done static lines back to back with other jumpers using vented and valved base canopies and i've had equal if not more canopy time. However this could be down to how we fly our canopies, wing loading and the canopy flight characteristics.

In an old thread, Tom A had some interesting views on how much difference vented and non-vented canopies made when static lined or PCA'd. (Tom would you like to comment as i may have misunderstood you) For sure when it comes to freefall the vents seem to come into their own.

Manbird. 4secs from a PCA at 170ft is far too little time even without vents. I've static lined under this height and had (relatively speaking of course) bags of canopy time. I have no idea what happened to you on that jump but maybe you were given a weak PCA (aka freefall assist). Of course this is just guesswork, but something doesn't add up there if you ask me.

I would be keen to hear from the Base manufacturers or some science boffin on what they believe (or know).

On the whole though, i would get the vents anyway. Makes sense if you're gonna freefall low.

All the best

ian

[ManBird]

Manbird. 4secs from a PCA at 170ft is far too little time even without vents. I've static lined under this height and had (relatively speaking of course) bags of canopy time. I have no idea what happened to you on that jump but maybe you were given a weak PCA (aka freefall assist). Of course this is just guesswork, but something doesn't add up there if you ask me.

There definitely seemed to be a freefall. The nightshot video from the ground made it impossible to tell whether the canopy just stayed in a wad after line stretch, or the PC and bridle were dropped. Definitely had a ground rush and felt/heard some speed before I was under a fully inflated canopy.