Reserve Canopy descent to landing?

[cjsitfly 0]

I know this question has so many variables it is hard to answer, but... Assuming a person deploys a 150sf reserve in light to no wind conditions and utilizes a cautious descent (not to exceed 360 degrees) what would the rate of descent be on average. i.e. 1000 feet per ? (in seconds)?

Thanks, just searching for answers for a friend who cutaway. It took 30 seconds from reserve opening to landing with a slow 360 turn.

Chris

[yarpos 4]

is the person of average weight as well (whatever average means in your country)......if I was making a really rough guess I would say 15 to 20 fps , so 30 secs under canopy would be maybe 450 to 600ft.....he would have been the guy with the big eyes when you picked him up

regards, Steve
the older I get...the better I was

[cjsitfly 0]

Yea, that's what I was thinking. I only cut away once, at 2000 (my basement for emergancy action.....so far anyway) and I remember a much longer flight time to landing. This person is average weight, 180-190 and cutaway at 1500, or so said. Their canopy ride was 29 seconds with a very slow 360 to hit the zone. It appeared really low to me but just wanted to verify before I passed on.

Chris

[JohnRich 4]

The general rule of thumb on canopy descent rate is 1,000 feet per minute. So if he was under canopy only 30 seconds, that would put his opening altitude at around 500 feet.

There are some variables here though, such as maneuvering of the parachute, or small fast canopies, which will make them dive out of the sky faster than others.

[pchapman 262]

I'd guess 1200 fpm is reasonable, for only slightly turning flight with no brakes. Sharper turns are of course much faster, while hanging out in brakes can be quite a bit slower.

(I've flight tested a few main canopies and was getting about 1000 fpm for big student stuff, 1200-1300 fpm for a 160 and 135, older squarish non-ground hungry designs, at say 170 lbs weight.)

Even if I'm off on my numbers, your friend seems to have been a bit on the low side.

[Andy9o8 0]

OK, now that we've settled that, tell us why your friend cut away so low.

[JohnRich 4]

Quote

OK, now that we've settled that, tell us why your friend cut away so low.

Quote:

"This person is average weight, 180-190 and cutaway at 1500, or so said. Their canopy ride was 29 seconds with a very slow 360 to hit the zone."

That's not really all that low.

The rule is you make the decision to cutaway by 1800', so actually getting it done by 1500' isn't that far off.

Then it's surmised he opened about 500', which would mean that he pulled his reserve, or it was deployed for him, at about 700' to 800'.

So the altitude that's unaccounted for is from 1500' down to 800'.

If the cutaway was at terminal velocity, that's only 4 seconds. That's from the time he cutaway, until he deployed his reserve. Not really exceedingly long, but maybe longer than necessary.

If the cutaway was from a partial malfunction, then the time from 1500' down to 800' is about 7 seconds. And that would be too long.

There are unknowns here, such as the type of malfunction, AAD, RSL, etc.

What this demonstrates is just how little time there is to waste when something goes bad. If he had delayed another 4 seconds, he's probably be dead. And 4 seconds ain't very long... About the length of time it took to read this last paragraph.

[Andy9o8 0]

You're right, I didn't read carefully; I should have asked him why his friend's reserve canopy deployed so low. Also good points in your discussion.

We'd still like to hear more from the OP...