Forums: Skydiving: Gear and Rigging:
Custom pilot chutes???

 


DrFlowers  (C 31800)

Sep 29, 2001, 4:05 PM
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Custom pilot chutes??? Can't Post

Anyone know of a reputable manufacturer that makes custom color pilot chutes?



skymedic  (C 33561)

Sep 29, 2001, 4:26 PM
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Re: Custom pilot chutes??? [In reply to] Can't Post

aerotech products.....My riggers company. and great gear bags too. See terry's web page!!!

Marc
Because I fly, I envy no man on earth


DBTECH  (B 21186)

Sep 29, 2001, 6:31 PM
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Re: Custom pilot chutes??? [In reply to] Can't Post

Jim Cazer makes many OEM pilot chutes.
I do recommend smaller ZP pilot chutes for better openings. (20"-24")
Dave Brownell

jimcazer@aol.com



Aviatrr  (D 27349)

Sep 29, 2001, 8:25 PM
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In reply to:
I do recommend smaller ZP pilot chutes for better openings. (20"-24")
Why is that? I get fine openings with a 28"ZP.. It will depend on the type of canopy, IMO.. Would you recommend a 20-24"ZP for a Manta 290? Granted, even a 20"ZP PC will probably produce 150+lbs of snatch force, but I don't think that smaller PC's are optimum for everybody..

Speaking of PC's, I've been thinking about something lately.. I'm considering rigging up a system so that I can deploy different types of PC's in freefall, attached to something that will measure the pull force, and then be able to cut the PC away(such as a 3 ring release) after getting a good measurement of force exerted by the PC.. So far, it seems that attaching it to the front of the rig, and deploying it while on my back is the best option.. Anybody have any kind of recommendations for scales for such a purpose?

Mike



mountainman  (A License)

Sep 30, 2001, 8:15 AM
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In reply to:
I'm considering rigging up a system so that I can deploy different types of PC's in freefall, attached to something that will measure the pull force, and then be able to cut the PC away(such as a 3 ring release) after getting a good measurement of force exerted by the PC.
Just wondering why you would want to do this, Mike??

--------------
Brandon Wren


riggerrob  (D 14840)

Sep 30, 2001, 8:27 AM
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Re: Custom pilot chutes??? [In reply to] Can't Post

Call Chris Kelly at Adventure Sports Loft in Perris Valley, California. She will sew you a custom pilotchute in any color you want. But her true specialty is custom applique on pilotchutes. Chris will take almost any piece of artwork (hint: keep it simple) and sew it onto a pilotchute. Besides the usual flags or yin/yan, Chris has sewn some truly sick and twisted skulls!
Chris is also a second source for Wind Signs, those banner type thingies that young men with tiny canopies scream between.



mountainman  (A License)

Sep 30, 2001, 9:09 AM
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In reply to:
those banner type thingies that young men with tiny canopies scream between.
hehe.....i like that description!! Smile

--------------
Brandon Wren


DBTECH  (B 21186)

Sep 30, 2001, 10:30 AM
Post #8 of 12 (1025 views)
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I said-> I do recommend smaller ZP pilot chutes for better openings. (20"-24")

Mike said-> Why is that? I get fine openings with a 28"ZP.. It will depend on the type of canopy, IMO.. Would you recommend a 20-24"ZP for a Manta 290?

DB> Of course not, but how many Manta 290's are being jumped by experienced jumpers?!

Mike-> Granted, even a 20"ZP PC will probably produce 150 lbs of snatch force,

DB-> First of all, a pilot has drag, not snatch force.

What is snatch force? Snatch force is defined as the peak and average force that is required to accelerate the slider, canopy, and bag back to the speed of the jumper. Snatch force begins at the point of last line stow release* and lasts only for several milliseconds. Less then eight milliseconds for the slider and more than forty milliseconds for the canopy. Some factors that effect snatch force are the fall rate of the jumper, (air speed) the drag of the pilot chute, (size) the elongation of the suspension lines, risers and harness, the packed height of the canopy and the mass (weight) of the canopy. Peak snatch force can actually exceed 300 pounds in some cases! This, however, lasts only for a few milliseconds before opening forces begin. This is the "jerk" that we feel just before opening shock. (source--an excerpt from the soon to be released article, entitled--

Fast openings/Slow openings--The Real Physics of slider rebound; plus invention revealed.
(Patent Pending) By David B. Brownell

NOTE: A 20" ZP pilot chute has about 50 lbs of drag at 120 MPH IAS.

Mike-> but I don't think that smaller PC's are optimum for everybody..

DB> This issue is covered, in my soon to be released article.

Mike-> Speaking of PC's, I've been thinking about something lately.. I'm considering rigging up a system so that I can deploy different types of PC's in freefall, attached to something that will measure the pull force, and then be able to cut the PC away (such as a 3 ring release) after getting a good measurement of force exerted by the PC.. So far, it seems that attaching it to the front of the rig, and deploying it while on my back is the best option.. Anybody have any kind of recommendations for scales for such a purpose?

DB> Forget about trying to do it in freefall. Use a pick-up truck. Install/fasten vertically, a small diameter EIGHT foot pole behind the cab. (3/4" water pipe) (bottom end at bed floor) The top of this pole can be held tightly to the cab top with lines attached to it that extend and fasten to the left and right points of the bumper. This method will eliminate having to install a mount at the cab's rear/roof line. The bottom of the pole will have to be held in place by other methods.

At the top of this pole install a large diameter pulley that will accept 1/4" line. Fasten a piece of said line at/near the bottom area of the pole. Fasten the other end of this line to a fish scale, so that the scale is at the center of the cab's rear window. Fasten a piece of said line to the top of the fish scale--thread the other end of this line through the pulley--the length of this line should be long enough to extend at least three feet beyond the pulley/pole to minimize turbulence from the pole. (allow 6" for knot)

The following "math" should yield fairly accurate results. To be done in no wind conditions--early morning.

At 60 MPH the scale reading is 25% of the drag at 120 MPH (reading X 4, for 120 MPH drag)

At 80 MPH the reading is 44.4% of the drag at 120 MPH (reading X 2.25 for 120 MPH drag)

At 100 MPH the reading is 69.44% of the drag at 120 MPH (reading X 1.44 for 120 MPH drag)

At 110 MPH the reading is 84% of the drag at 120 MPH (reading X 1.2 for 120 MPH drag)

BTW: The higher the truck speed, the greater the accuracy.

Good luck with your project-I would appreciate any numbers.

Skies,

Dave Brownell

Mesa, AZ





(This post was edited by DBTECH on Sep 30, 2001, 2:36 AM)


cobaltdan  (D License)

Sep 30, 2001, 12:13 PM
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hi mike,

when i saw you post i had a bunch of stuff to reply, but
db pretty much covered it !

a while back we were noticing some iniatial high spike opening force during some tests (we have a datalogger connected to 4 riser load links as well as helmet mounted accelerometers). anyway we traced the spike to the pilot chute.

we wound up recording the force vs time curves for 28", 24",22",& 20" pilots that were custom made for us by jim cazer. we did this by throwing them from the back our f150 at 70mph using the datalogger and 1 load link. we then extrapolated the data out to 140 mph.

we recommend 22" for cobalts 135 and smaller, for the 150-170 we typically recommend 24"
both zero p collapsable.

sincerely,

dan
atair aerodynamics
www.extremefly.com



Aviatrr  (D 27349)

Sep 30, 2001, 2:52 PM
Post #10 of 12 (1014 views)
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Re: Custom pilot chutes??? [In reply to] Can't Post

In reply to:
we wound up recording the force vs time curves for 28", 24",22",& 20" pilots that were custom made for us by jim cazer. we did this by throwing them from the back our f150 at 70mph using the datalogger and 1 load link. we then extrapolated the data out to 140 mph.
What kind of numbers did you guys come up with for the different PC's? I've heard everything from 50lbs drag for a 20"ZP, to 300lbs drag for a 28"ZP.. During your tests, what kind of scale did you use? I've heard several people say try a fish scale, but I don't know of any that go up to the kind of weights required.....but then again, I'm not a fisherman, so not really familiar with those things..

Mike



Aviatrr  (D 27349)

Sep 30, 2001, 3:01 PM
Post #11 of 12 (1014 views)
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Re: Custom pilot chutes??? [In reply to] Can't Post

In reply to:
Of course not, but how many Manta 290's are being jumped by experienced jumpers?!
Manta 290 was just an arbitrary canopy choice, but there are many experienced jumpers out there jumping 170's, 190's, 210's, etc..

In reply to:
First of all, a pilot has drag, not snatch force.
Ok, bad terminology on my part...I was referring to drag, just used the wrong words..

In reply to:
Good luck with your project-I would appreciate any numbers.
I'll see what I can rig up with a vehicle, but I think ultimately this will be done by deploying an anchored PC - several of them, actually, on different jumps - in freefall.. Doing that type of test with a truck just wouldn't be as fun, and you know what happens when skydivers get bored..

Mike



cobaltdan  (D License)

Sep 30, 2001, 9:24 PM
Post #12 of 12 (996 views)
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Re: Custom pilot chutes??? [In reply to] Can't Post

we used a load link sensor connected to a digital data acquisition recorder.
tension in increments of ~1.56# is recorded at a rate of 200 times per second.

a fish scale will not give you a force vs. time graph or even peak force for that matter.

from memory our 22" were giving us 50-60# steady state. posting the graph data it is on our list of things to do for our web programmer.

-dan
atair





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