Forums: Skydiving: Gear and Rigging:
Pop tops ?

 


Vlad  (A 38183)

Jul 9, 2001, 4:36 PM
Post #1 of 5 (1168 views)
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Pop tops ? Can't Post

I have heard different opinions about pop-tops. I've heard that they are better because there are less flaps in a way of reserve canopy. Mirage states that poptops are bad, because of their "limitations these designs impose on pilot chute design" . Have there been studies on this topic ?



Premier skybytch  (D License)

Jul 9, 2001, 7:26 PM
Post #2 of 5 (1152 views)
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Re: Pop tops ? [In reply to] Can't Post

The "true" poptop is the two pin Racer. There are other rigs out there with an exposed reserve pilot chute but the manufacturer of the Racer would prefer that you not refer to them as "poptops." I'll call them "exposed"; I kinda like the sound of that.

The exposed reserve pilot chute has been around for a looooonnngggg time - they were first used on belly reserves back when relative work was just starting. Fewer flaps meant less bulk to the reserve container, which in those days translated into faster exits.

Having fewer flaps covering the pilot chute does allow for a bit faster reserve deployment - it's been proven in tests. Hey, what if that extra second was the one you needed?

I can't think of any limitation on pilot chute design the exposed reserve pilot chute would create. Perhaps in container design? Rob? Chime in here.

pull and flare,
lisa
----
I don't think much, therefore I might not be


ramon  (D 26115)

Jul 10, 2001, 8:12 AM
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Re: Pop tops ? [In reply to] Can't Post

Spectre 230 said the spring on a racer is not strong, but it does not need to be. Packed correctly there is nothing keeping the pilot chute from springing off the back.

It is a racer jumpers proud feat to go to his riggers for a re-pack, pull his reserve ripcord and have his poptop shoot across the room.

Talons are not pop tops and have very strong springs if this is necessary or not, I don't know, but it is definitely intended to get the pilot chute away from the flaps.


Reflex's are pop tops also. The c-flex has tiny little flaps designed to keep a line from going under neath it, but still I would perform Crew in a different rig. Fliteline (manufacturer of the Reflex) just went out of buisiness due to law suits. Another company will be taking over their, parts buisiness, so until they come online, if you have a mal, try your best to recover your free bag Laugh. Also I have never had a problem with my reflex (600 jumps on it, 400 mine mostly freeflying). you just have to make sure the pop top is tight, and you want your rigger to do this. If your rigger tightens your poptop really tight, always make sure you check your reserve pin, If it is crimped (sharp bend at the closing loop) ground the gear and tell your rigger this can give you an impossible pull situation. If there is a barely perceptible bend in the pin it is okay. You rigger should be able to hook a scale to your reserve cable and I beleive it should take less than 18 pounds to pull.
Rob correct me If I am wrong .

Racers do not have this problem, becaus they have two pins, so they are very neat and cosmeticaly pleasing when packed right, however some riggers dislike packing them because of the difficulty.

I like my reflex and cheap as it was I have had one riser flap undone on video and it was undone when I left the plane. Mine is very snug and never gives me any problems.

However my next rig will be a Vector III micron. I think they are designed the best (all rigs are pretty damn good these days, if there is a quality program in effect during manufacture, but I believe Vector leads the way)

bloo skies
ramon



riggerrob  (D 14840)

Jul 10, 2001, 5:03 PM
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Re: Pop tops ? [In reply to] Can't Post

History lesson: Dan Poynter designed the first Pop-Top as a chest mounted reserve when he worked for Strong. He assigned the patent to Strong Enterprises who subsequently built chest, back and seat versions. The seat and back Pop-Tops are still in production as pilot emergency parachutes.
In the mid 1970s John Sherman got a license to use the Pop-Top reserve in one of the first piggyback skydiving rigs. Sherman's SST skydiving rig evolved into the SST Racer and eventually the Racer Elite Tandem. Innumerable companies built licensed - and otherwise - Racer copies called: Excaliburs, Sod Shit, Chasers, early Teardrops, etc. All the early Pop-Tops had two pins.
Sherman experimented with one-pin Pop-Tops but was never able to transfer the load from the central loop to the circumference without ridiculous pull forces.
In the 1986 a South African named Snowy Dickinson built a copy of a Vector Tandem with numerous detail changes. The most important of those changes was a single-pin Pop-Top with - what looked like - an aluminum pie plate to distribute the load to the circumference. The secret was the domed cap which distributed the load without requiring ridiculous pull forces. From this point onwards we can no longer legally call them "Pop-Tops", but it is a convenient term.
Dickenson never put his rig into production, but his idea was copied and improved by my German buddy Stefan Ertler. Sorry Stefan, I know the following statement will hurt your feelings, but the truth will ultimately win out. More than two years after I published an article - and photo - about Dickenson's rig, Ertler applied for a German patent on the one-pin Pop-Top.
Ertler subsequently licensed his patent to Thomas Sports Equipment of Britain who built large numbers of single-pin Teardrops with aluminum caps.
Circa 1994, Micky Cottle of California decided to copy the single-pin Teardrop reserve design when he started building Reflex containers. Cottle's biggest modification was to build his caps out of carbon fibre composites.
Personally, I don't believe all the advertising hype about Racer reserves opening significantly faster. That advertising hype conveniently ignores the 12 grommets, plus two Cypres cutters the loops have to clear before the pilotchute can launch. In comparison, a Javelin's loop has to clear 3 grommets before the pilotchute can launch.
As to whether Pop-Tops are easy to pack, it depends upon who you ask. It took me 10 years to get good at packing Racers. Along the way, I scrapped a series of metal bodkins and developed an adjustable temporary loop that is Cypres compatible.



Premier PhreeZone  (D License)
Moderator
Jul 10, 2001, 5:44 PM
Post #5 of 5 (1038 views)
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Re: Pop tops ? [In reply to] Can't Post

Very nice reply Rob!

Whoa... That was cool!



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