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CloudyHead

Two canopy out.. to release or not release?

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IJskonijn

***I still wonder why so many sources say "don't flare a biplane". I've seen it done with a very good landing. Anyone with a definitive answer?



Page 4 of the dual square report (found on the PD website: http://www.performancedesigns.com/docs/dualsq.pdf) says:

PD dual square report


Landing a personal biplane proved to be easy with large canopies, small canopies, heavily loaded canopies, and lightly loaded canopies. Flaring the front canopy seemed to be the preferred method of landing. However it must be noted that flaring the front canopy, or both, did not produce a significant effect in the landing. The canopy would pitch in attitude, but it did not plane out or slow in descent rate much if at all. The descent rate on all canopy combinations was very slow, even in full flight.

Recognizing the student and novice jumpers propensity to flare high, combined with the non effectiveness of a dual square flare, leads us to believe that not flaring at all is the best way to land a dual square.

conclusion: If a biplane is present and the jumper has directional control, leave the brakes stowed on the rear canopy and fly the biplane using gentle toggle input on the front canopy. Do not flare either canopy for landing. Be prepared to do a PLF.



The Army's intent was to try to deploy both canopies at exactly the same time to see if they would entangle. They showed video of these jumps and no matter how hard they tried the canopies both fully opened. On one jump the bag of one caught under the slider of the other momentarily. This and the subsequent PD testing and Dual Square report were mainly prompted by the growing acceptance of the Cypres AAD. A.A.D. (Vigil) wasn't around yet. The only scary moment in the Army's videos was when the main in front of a reserve in a biplane was chopped. One of the risers tried to snag the reserve lines as it slide up the front. That was enough to not want to chop a biplane if you didn't have to.

I had a low level PC in tow, dumped the reserve and had both canopies opening above me as I went into the trees. Not fully open but both ended up in the tree separate from each other. What I still haven't explained is the Swift F111 free bag had friction burns through the material but no part of the reserve or the main was damaged. It went up something at high speed, perhaps the main lines or main PC but the canopies still didn't entangle.

Also remember that none of these tests were done with high performance elliptical canopies. All bets are off on what might be stable or not with the high performance little stuff. Any videos of a Velocity spinning around a reserve? Line twist used to not be a malfunction but often requires instant cutaways on the little stuff before they spin too fast.:S And remember that these are dynamic systems. I watched a student side by side on a Manta and Raven IV that was stable for 1500' decide to transition to a downplane at 100' and severely injure the student. No input from student as far as we could tell.
I'm old for my age.
Terry Urban
D-8631
FAA DPRE

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