Why different actions when Two canopies out

[Lyud 0]

Why are different actions in solo jump and tandem jump when Two canopies out? 

In SIIM
Stable biplane
Unstow the brakes on the front canopy or leave the brakes stowed and steer by pulling on the rear risers and recover gently to full flight.

In Sigma Manual
...leave the brakes stowed on both canopies and make gentle control inputs by pulling down on either of the left or right rear risers of the front canopy to initiate turns

[pchapman 261]

So the two sources are the same for biplanes, except for the SIM allowing the option of unstowing the brakes on the front canopy and steering with them.

I don't think there is one standard procedure in the world that everyone agrees on because it isn't as if it gets tested a lot.

Nevertheless, I get the feeling that over time, the tendency has become to recommend a more 'conservative' approach, not unstowing the front brakes in a biplane.

From a 2013 post of mine:

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these are my sources, that suggest that leaving toggles stowed and using risers is best:

 

-- Jim Cowan of CPS at PIA 2009

-- John Leblanc of CPS in a 2004 lecture

-- the CSPA manual  (PIM 2 rewritten 2010) [2020 note: although makes use of Jim Cowan's work]

 

These are in contrast to the Dual Square Report presented at the PIA in 1997, which mentions flying the front canopy in a biplane, or the 'dominant' canopy in a side by side, with gentle toggle input.

 

(However, it never explicitly mentions releasing toggles, what to do if certain toggles are released or not, or toggle positions for matching a canopy that has toggles set. Thus my opinion is that the toggles issue might not have been thought out as much at that time as in later publications.)

 

The USPA SIM basically follows the Dual Square Report, but is explicit about releasing toggles in order to steer.

The APF also used toggled stowed -- And it says it is based largely on the PIA report, but with updates based on more recent field tests.

I also have a note about the USPA SIM, although I didn't note the year. Perhaps also 2013 or so?  Has this explanatory text been removed since then?  I haven't checked. Anyway, here's the SIM note:

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While it does mention toggles, it also says:

 

"The landing with both brakes stowed option was added as an option in the SIM based on personal observations by some Board members of uneventful landings with brakes stowed on both canopies, and test jumps performed by Jim Cowan. The test jumps were not as extensive as the PIA dual square, but provided enough information that the Board wanted to include the information as an option."

As you can see, historically much of the input on the subject in the past 20+ years is basically the PIA dual square report, with modification later based on Jim Cowan's tests.

[riggerrob 558]

Yes, electronic Automatic Activation Devices (e.g. Cypres) were introduced circa 1991 and we saw a dramatic increase in two-out malfunctions (biplane or side-by-side).

A few skydivers died after they made too-vigorous control inputs which converted slow two-outs into fast down-planes.

I have only experienced one two-out malfunction and that was because i - stupidly - spiraled below 1,000 feet, fast enough to scare an FXC 12000 AAD. The reserve inflated behind me and formated in a docile biplane. I tried steering the leading/main canopy, but it kept trying to separate into a side-by-side, so I reduced control inputs to the bare minimum. It took me 500 to make my last turn into the wind and I slid out my landing on wet grass (normal landing field). My two-out descended much slower than a Solo 270 student canopy, so there was little risk of injury when sliding the landing.

Lessons-learned: A - only minor control inputs below 1,000 feet.

B- Bare minimum of control inputs when you have two canopies out. As long as you are headed for an open field, that is good enough. Up-wind,down-wing or cross-wind is less important than keeping both canopies overhead.

A few sk

[Lyud 0]

I am interested of emergency procedures with two canopies out for students categories A,B or C. They didn't learn the steearing by rear risers  yet.

What will be safer, for example, with side-by-side canopies?

Leave the brakes stowed and steer by pulling on the rear risers or release the brakes and steer with the toggles?

The student may be in panic and make mistakes.

There was a bad situation with a student recently. The main was 270 sq.ft, the reserve was 255 sq.ft. The student made a mistake, release toggles on the reserve and after stable side-by-side became downplane.

I think so way: teach the students leave the brakes stowed and steer with rear risers when they have biplane or side-by-side canopies. But if the toggles were unstowed earlier then two canopies out, then steer with the toggles.

[riggerrob 558]

WE teach students to steer the front canopy when both inflate. We also teach them to steer very, very gently.

[Lyud 0]

14 hours ago, riggerrob said:

WE teach students to steer the front canopy when both inflate. We also teach them to steer very, very gently.

This is clear. But do you teach the students to steer by pulling the rear risers OR release the brakes and steer with the toggles when both inflate?

[skytribe 16]

The mere fact that CRW jumpers fly biplane configurations all the time and fly with toggles, should be a good indication that flying with toggles is not a bad decision.   Flying gently the front canopy and no big inputs is also a good strategy.   Leaving the rear canopy set in brakes result in a slower canopy with less force being put on the brake lines of the front canopy.   Sometimes canopies just dont like flying together if their performance characteristics are very dissimilar.  

You don't see big inputs from CRW stack pilots when flying formations.  They steer and all the canopies below them follow with no input from the jumpers.  They tend to fly similar canopies though - at least these days even if they may be different sizes they are on similar wing loadings/glide ratio's  (example lightning and 1.3 lbs/sq foot loading)   But that isnt always the case and certainly in the past wasnt.

   As for steering using rear risers - IMHO it creates a different set of problems.   Flying a huge tandem canopy with rear risers is difficult at best and results in very small movements (which may not be a issue). Some small tandem jumpers may have trouble pulling enough to make a 360 sq foot canopy turn.   Flying a Ultra high performance canopy may result in more radical control input with little input.     People are happier flying with toggles and it gives a better degree of control than trying to grip rear risers and provide a precise degree of control.

I think the best advice is to do all you can to avoid the problem in the first place. 

 

[pchapman 261]

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The mere fact that CRW jumpers fly biplane configurations all the time and fly with toggles, should be a good indication that flying with toggles is not a bad decision.   [...]    Sometimes canopies just dont like flying together if their performance characteristics are very dissimilar.  

The 2nd part of that quote is the key caveat to the first part. As you say, in CRW the canopies are well matched.

I think much of the issue is not "does one steer with toggles?", it is whether one releases the toggles in the first place in order to steer!

I don't see as much risk in just steering with toggles if they are already released. Toggles or risers, use whatever works for you.

But releasing them can make things worse if the main and reserve canopies are not well matched.