How quickly do tandem reserves open?

[gus 1]

A question inspired by this post where Aubrey says he's using a tandem reserve in his (solo) rig.....

I thought a TM had once told me that tandem reserves were designed to open slowly (ie 1000+ ft). Is that the case? If so and if you're using one presumably your hard deck needs to be significantly higher than if your reserve was designed to open in 300 ft.

Gus

OutpatientsOnline.com

[riggerrob 643]

After 14 rides on Strong Master 425 reserves, I can tell you that they open softly at low airspeeds (i.e. after cutting away a damaged main), but brutally hard at terminal. I was seeing stars at high noon!

[d604 0]

Which terminal Rob, normal or tandem terminal that’s a big variable.
Sean

CSPA ratings C1, C2, IA, IB, QE, RA, and EJR

[riggerrob 643]

I stars at high noon after a tandem terminal reserve opening on a Strong Master 425 reserve!

[Liemberg 0]

AND it seems to have affected your memory too...

"Whoever in discussion adduces authority uses not intellect but memory." - Leonardo da Vinci
A thousand words...

[flipper 0]

agree 100%...they are slow

[skydiverton 0]

They are packed to survive (canopy and jumpers) a tandem terminal (170knt) Thet means these reserves take their time to open after a low speed cutaway. Opening fast at a low speed cutaway would result in a damaged canopy/jumper at tandem-terminal.

This is one of the reasons tandems open higher
Just to prevent

I experienced a couple of tandem cut-aways (vector). The longer opening timesdid not bother me. They were a little quicker than a tandemmain opening

++++++++++++++++++++++++++++++++++++++++++++
Using your droque to gain stability is a bad habit,
Especially when you are jumping a sport rig

[atsaubrey 0]

Then I have a question, if they do indeed open slower. Are they packed to open slower or are they designed that way or is it a combination of both? If it is just packed differently, I am confident my rigger packed it to open fast.

"GOT LEAD?"

[councilman24 37]

Through TSO C23c, all emergency parachutes had to meet the same opening time requirements. With TSO C23d, parachutes with a max operating weight greater than 250 (whether tandem or not) are allowed extra time or distance to be funtionally open. This is calculated by a formula and adds two or three seconds to the opening time allowed. Under the proposed standard for TSO C23e, just finished in January at PIA's meeting in Reno, this adjustment for canopies intended for heavier loads is retained but modified.

So yes, Tandem reserves certified under d and in the future will be ALLOWED to open slower. This can be a function of both design and packing method specified. The test is of the canopy and it's packing method in the manual. A rigger should (must) follow the instructions, so if originally designed (including the packing process) to open slower as allowed under TSO C23d, it will open slower than a reserve designed for a Max weight of under 250 lbs. There is no requirement that the over 250 lbs canopy MUST be designed to open slower, but it MAY be designed to open slower.

Anything TSO'd under TSO C23c had to meet the same opening speed requirements, no matter Tandem or not.

So no, in theory and under law your rigger can't just pack your reserve to open faster or slower. In reality slower might be possible, but most reserves are packed to open as fast as possible (to meet the test requirements) and big ones will be designed to open slower, probably but, not necessarily, with the fastest opening pack job.

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

[billbooth 10]

During the first year of tandem (pre-drogue) we had a rather difficult time keeping our mains in one piece on 170 mph tandem terminal openings. The joke going around at the time was that the real purpose of a tandem main was to slow you down enough so that you didn't blow up your reserve too. We kept playing with line trim, brake setting, slider size and shape, and crossporting, until we got our mains to open "softly", even at tandem terminal (no drogue). After all, you don't have a drogue on your reserve, do you?

The 360 Vector Tandem Reserve we use today is the same canopy as our "perfected" 360 main from 20 years ago, which had about 10,000 jumps put on it as a main, before we went to the drogue. This must make it the most thoroughly tested reserve ever marketed. It is designed to open in stages, slowing you down a little at a time, so that the faster you are going, the longer it takes to open. That is one of the main reasons I set minimum tandem main opening altitude at 4,500 feet, and why tandem AAD's are set to open at about 2,000 feet. I myself have over 250 tandem terminal openings on the canopy as a main, and it never hurt me (well, not very much anyway). I remember doing five, 170 mph openings on the canopy in one day. Try that on your average sport reserve.

The design has worked out very well. In 20+ years I don't think we have ever had one significantly damaged in actual use. By the way, the 360 was was the first tandem reserve the FAA approved, and was TSO'd under a special exemption to TSO c-23 B. The tests I devised for it then, are more stringent than those for a tandem reserve today, under either TSO "D" or the new "E".

[FrogNog 1]

Quote

So no, in theory and under law your rigger can't just pack your reserve to open faster or slower.

Academically speaking, I assume if the manufacturer tested certified two different packing methods, then the rigger could have a choice whether to pack to open faster or slower.

I do agree with your main point that the rigger is supposed to follow the reserve mfgr's instructions, however.

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