Forums: BASE Jumping: BASE Technical:
PC recommended sizes
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AntoineLaporte

Jan 15, 2017, 5:56 AM
Post #1 of 23 (3331 views)
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PC recommended sizes Can't Post

Hey,
I think it's time to rewrite the PC recommended size table by changing the "delay" with the ontrack speed.
With all the different suits we can wear nowadays the usual table does not make so much sense anymore.
A lot of people are flaring before pitching and so they are pitching in lower speed but everybody is continuing to use 36" PCs for wingsuit like it's the right size for everything after 10 seconds.
after 10 seconds in a slick jump we are way faster than after a flare in a medium/big wingsuit.
The second thing is the canopy weight and the big difference between light canopy with light lines and the heavy version.

Be welcome to let you comment here, pros or cons are welcome.

GreenMachine

Jan 15, 2017, 1:30 PM
Post #2 of 23 (3218 views)
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Four Variables [In reply to] Can't Post

Canopy Weight
Jumper Weight
Air Density
Air Speed

AntoineLaporte

Jan 15, 2017, 2:22 PM
Post #3 of 23 (3187 views)
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Re: [GreenMachine] Four Variables [In reply to] Can't Post

Canopy weight and speed I already said I agree.

Pilot weight ? What does it change for the PC ? The container opens, the PC inflates, slows the canopy in the air while the jumper continuing to fall until line stretch. I don't see the pilot's weight influence in this action.

I could agree for the air density but I need some estimation of the change on the PC action. For now I think it's not really relevant until I will change my mind with good numbers.

W_Heisenberg

Jan 15, 2017, 4:47 PM
Post #4 of 23 (3146 views)
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Re: [AntoineLaporte] Four Variables [In reply to] Can't Post

What size PC to you use for a 245 UL canopy with a TS/Onesie?

maretus

Jan 16, 2017, 1:01 AM
Post #5 of 23 (3034 views)
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Re: [W_Heisenberg] Four Variables [In reply to] Can't Post

W_Heisenberg wrote:
What size PC to you use for a 245 UL canopy with a TS/Onesie?

I think this is a very good topic and should be discussed! A lot of pilots dont really think about the speed (vertical / horizontal) when thinking about their PC choice but rather use charts dating back to the ages of slick jumping.

Personally I`ve come up with the following PC use for my terminal jumps:
- 245 UL Troll + PTS -> I use 36. Ive tried out 38 as well and to be honest dont really notice that much difference but as the 36 yields good opening as well Ive gone with that
- 265 normal Troll + PTS -> I use 38. Ive tested the 36 as well but the openings are way too slow and mushy for my taste.

Ive reasoned that this is due to the significant weight difference on my canopies (245 UL vs 265 normal) and the heavier one needs bigger PC for the same setup. For wingsuiting (any canopy) Ive always used a 38 but Ive been retired from that stuff for couple of years so my experience is a bit outdated on that. It will be very interesting to see what PC Ill end up using with a Onesie. Anyone have any expriences on those they could share?

Mikki_ZH

Jan 16, 2017, 1:29 AM
Post #6 of 23 (3021 views)
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Re: [maretus] Four Variables [In reply to] Can't Post

I weight 76 kg (167lb) and when I startetd wingsuit base, (around 10 years ago) I jumped a 32 pc.
After I saw Lutz push up his 32 PC into the legpouch and almost going in for not finding it, I upgraded to 34 PC.
As the pitching speed is reducing all the time because you should flare modern wingsuits, I know upgraded to 36 pc and I think this is the optimal size for the time beeing.
I jump various atair canopies (Trango1, 2, 3, peak, niner), all 245

Lucifer

Jan 16, 2017, 4:40 AM
Post #7 of 23 (2959 views)
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Re: PC recommended sizes [In reply to] Can't Post

here's an updated chart that already has a few years but it's adapted to the modern trends

adjustments to compensate for canopy weight are not taken into account as it's something jumpers start thinking of when already quite experienced - and it's arguably more about comfort than safety (yet definitely a parameter that enters the equation i agree)
Attachments: PCtable.jpg (251 KB)

GreenMachine

Jan 16, 2017, 5:17 AM
Post #8 of 23 (2946 views)
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Re: [AntoineLaporte] Four Variables [In reply to] Can't Post

As most people know, I do not fly in
Sleeping Bags of Death, but I have
jumped in tracking suits and big
ass camera wings, so I follow...

As for air density, I have free fallen from 100
meters or 328 feet many times. Here in FL
I have done this with a 42, 46, 48 both with
and without vents. They All Worked Fine.

However, in Twin Falls or Moab where the field
elevation is over 4,000 feet Mean Sea Level,
I would NOT personally use a vented 42 PC
but am sure Jesse Hall could do it just fine.

Cold air is denser than Hot air, so if I am
just on the line between two sizes then
the temperature would influence me.

I had a student who was 100 pounds, her
BIG pilot chute was a 46 vented. Where
as a student who weighs 200+ pounds
will have 48 unvented as their BIG pc.

In my experience, bigger people jumper
bigger canopies, which weigh more and
just need more drag to open ideally.

Open a brand new pillow case and then
open a brand new king size bed sheet.
The former takes more time to unfold.
Things do NOT scale perfectly linearly.

TomAiello

Jan 17, 2017, 7:10 AM
Post #9 of 23 (2718 views)
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Re: [AntoineLaporte] PC recommended sizes [In reply to] Can't Post

Honestly, I don't think a "universal" table is possible.

Every jumper should be using their own "table" based on their own gear and jumping style.

I know guys using 40" PCs for wing suit jumps who appear to be making good choices for what they are doing, and guys using 32" PCs for track suits who also seem to be thinking about it. And they are all getting good results.

TomAiello

Jan 17, 2017, 7:12 AM
Post #10 of 23 (2715 views)
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Re: [Lucifer] PC recommended sizes [In reply to] Can't Post

Are you using the same size PC for wing suit as for track suit?

jools

Jan 17, 2017, 8:15 AM
Post #11 of 23 (2674 views)
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Re: [TomAiello] PC recommended sizes [In reply to] Can't Post

I personally think people worry far too much about the PC size and not nearly enough about the construction/type/manufacture.

Not all PC's are created equal and a well constructed 42" PC can generate a lot more pull force than a poorly constructed 48" PC.

I have had much better results with a 42" Toxic than a 46" PC from other manufactures but would be happy jumping either.
I am also happy to jump a 38" Toxic sub 300ft which according to the old charts is black death.


A really simple way to gain confidence in any PC is to throw it out of the window of a car at say 20-30mph and then think about the forces needed to pop your pins and lift the canopy to line stretch.
Alternatively tie it to a load cell or even a spring balance.
Top Tip: Don't tie it to your wrist.


(This post was edited by jools on Jan 17, 2017, 3:36 PM)

TomAiello

Jan 17, 2017, 11:05 AM
Post #12 of 23 (2609 views)
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Re: [jools] PC recommended sizes [In reply to] Can't Post

I definitely agree.

It seems like people think the only variable between pilot chutes is the size, when there are actually a lot more (and more important) things going on than that.

BCSOG

Jan 17, 2017, 8:53 PM
Post #13 of 23 (2486 views)
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Re: [TomAiello] PC recommended sizes [In reply to] Can't Post

Tom, what do you think of the quality in regards to the Snatch.I know alot of people don't like how it's manufactured in Vietnam but I suspect it's more to do with brand loyalty like Ford vs Chevy and so on, after all, I've never heard anyone complain about the quality of ozone, and supposedly squirell's products are manufactured at the same facility.

TomAiello

Jan 18, 2017, 6:08 AM
Post #14 of 23 (2382 views)
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Re: [BCSOG] PC recommended sizes [In reply to] Can't Post

I've never had any issues with construction quality on the Snatch.

My thoughts (in the other thread on the Snatch specifically) relate to design, not construction.

AntoineLaporte

Jan 19, 2017, 6:48 AM
Post #15 of 23 (2222 views)
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Re: [jools] PC recommended sizes [In reply to] Can't Post

The table is a base to choose your PC not the truth.
Has it exists a better one might help to have better choices.
I for example never use something under 38. If I slide at the exit I want to be able to pitch before 3 or 4 seconds slider up and have a PC that is doing the job with that kind of delay.
The best way to choose it to put you sacred Gopro filming backward and to see if you bridle is tight or not during extraction.
If it's tight get a size down until it's getting arched. Then go back to the size up to this one.
For once there is a very good use to the Gopro so use it.

edited thanks to the next post


(This post was edited by AntoineLaporte on Jan 19, 2017, 8:32 AM)

REDAKTOR

Jan 19, 2017, 8:25 AM
Post #16 of 23 (2178 views)
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Re: [AntoineLaporte] PC recommended sizes [In reply to] Can't Post

AntoineLaporte wrote:
The table is a base to choose your PC not the truth.
Has it exists a better one might help to have better choices.
I for example never use something under 38. If I slide at the exit I want to be able to pitch before 3 or 4 seconds slider up and have a PC that is doing the job with that kind of delay.
The best way to choose it to put you sacred Gopro filming backward and to see if you bridle is tight or not during extraction.
If it's tight get a size down until it's getting loose. Then go back to the size up to this one.
For once there is a very good use to the Gopro so use it.
Are you sure that's sound advice? Because to me a loose bridle during deployment = burble = pc in tow = well, deathCrazy

AntoineLaporte

Jan 19, 2017, 8:31 AM
Post #17 of 23 (2173 views)
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Re: [REDAKTOR] PC recommended sizes [In reply to] Can't Post

By loose I mean not straight, like arched.
Yes probably wrong words.
Thanks for notice it.

wasatchrider

Jan 19, 2017, 10:32 AM
Post #18 of 23 (2109 views)
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Re: [AntoineLaporte] PC recommended sizes [In reply to] Can't Post

AntoineLaporte wrote:
The table is a base to choose your PC not the truth.
Has it exists a better one might help to have better choices.
I for example never use something under 38. If I slide at the exit I want to be able to pitch before 3 or 4 seconds slider up and have a PC that is doing the job with that kind of delay.
The best way to choose it to put you sacred Gopro filming backward and to see if you bridle is tight or not during extraction.
If it's tight get a size down until it's getting arched. Then go back to the size up to this one.
For once there is a very good use to the Gopro so use it.

edited thanks to the next post

ever done a go and throw with a 36 or even 32? they work pretty good
would not recommend testing this on the side of caution which is why we use such big pilot chutes
ive seen a 1 sec delay with a 36 on a cliff and came out right away, same thing with a 32 out of a balloon

AntoineLaporte

Jan 19, 2017, 10:38 AM
Post #19 of 23 (2105 views)
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Re: [wasatchrider] PC recommended sizes [In reply to] Can't Post

There is a difference between i've done it and it worked and i would recommend it.
Any video ? You think it's the best ?
Where is the point BTW ?

wasatchrider

Jan 19, 2017, 11:09 AM
Post #20 of 23 (2084 views)
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Re: [AntoineLaporte] PC recommended sizes [In reply to] Can't Post

AntoineLaporte wrote:
There is a difference between i've done it and it worked and i would recommend it.
Any video ? You think it's the best ?
Where is the point BTW ?

No point really just 38 is overkill for me but have used it for terminal tracking and wing suit. I use a 36 now down to 4 sec delays anything let I'll use a bigger one.

TomAiello

Jan 19, 2017, 2:01 PM
Post #21 of 23 (2017 views)
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Re: [wasatchrider] PC recommended sizes [In reply to] Can't Post

I tested down to 38" on go and throw many years ago, in an attempt to reduce hesitations.

With the 38, the lower drag force (and resulting slower extraction) were unacceptable for me.

I did a lot of low jumps on a 42 though.

With a lighter PN-9 canopy (which didn't exist back then) you could probably downsize PC's quite a bit.

AntoineLaporte

Feb 13, 2017, 5:18 AM
Post #22 of 23 (1465 views)
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Re: [TomAiello] PC recommended sizes [In reply to] Can't Post

A very good article from the Squirrel team about PCs.
To be read !
http://base-book.com/...action-and-inflation

DropBearBase

Mar 26, 2017, 8:02 AM
Post #23 of 23 (730 views)
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Re: [W_Heisenberg] Four Variables [In reply to] Can't Post

36' no need for the 38. iv tested both with a onesie and sausage with a 245 and the 36' is super efficient. just don't flare hard as you will risk stalling and super low airspeed.


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