Elastic ringed spill holes?

[Winston]

Got the idea from a WWII parachute packing video I just watched. Those chutes had elastic ringed spill holes that opened at speed to reduce opening shock and closed at lower speeds to lower descent rate.

 

[Handeman]

Sounds like a good idea.

How was the pattern of the canopy modified to allow the opening and closing? The standard pattern of gores wouldn't allow any opening or closing of the spill hole unless you had very strong elastic and that would affect the whole canopy. The strength of the elastic would also have to be sized to the chute and the loads.

A good idea, but I think it would take a lot of engineering and testing if you can't find all the design info from way back when. Knowing the government, that's probability still classified.

 

[dhbarr]

Make a PDA/toroidal, but for the inner shroud lines use elastic, braided together at the appropriate height then joined to the outer shroud bundle.

Or non-PDA , cut your gores such that a cylinder is formed at the peak instead of a hole. Gather the tip w/ elastic, presto.

 

[Coop]

Interesting, but seems like such a design would not be maintenance-free like most other hobby chutes. Performance would start to degrade as the elastic does. The PDA mentioned, above, would be a particular PITA to replace lines on --but would probably work the best out of 'em all when it was working. Then again, I've had my fill of apex lines for today --just finished a nonelastic version about 30 mins ago-- the main lines are one thing... the PDA lines were giving me fits.


Later!

--Coop

 

[dhbarr]

Make your normal non-PDA w/ ~20% spillhole, but for some portion of some of the seams sew buttonholes or similar.

Small elastic loops or lacing to keep these seams normally closed, but at mid-speed deploy they'd open until your airspeed fell; at hi-speed they'd peel like an orange and you'd have a 40% spillhole

 

[dhbarr]

No spillhole, top triangular flaps able to hinge open. Buttonholes in all gore tips, one single loop of elastic. Should swell out to 20% spillhole under strain, also 'burp' a bit to counteract sway.

 

[Winston]

Here's the video I watched at the point the "puckered vent" is mentioned and shown:

Parachutes: Construction and Types ~ 1942 US Army Training Film; Intro to Parachutes

https://youtu.be/l2AxlUzYb6I?t=3m15s