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Why are the vents on vented canopies placed toward the nose of the wing rather than toward the tail? It would seem to me that they do more good there than anywhere else to prevent collapse.

Only because that would fuck up any and all aerodynamic qualities of a ram-air canopy

The point of vents is to promote inflation, not to prevent collapse.

Inflation happens at the nose.
if you were to try to inflate from the tail (if that's even possible), you would loose heading performance and induce lineovers.

here's a pic of a canopy just finishing inflating in a no slider environment

ok, that makes sense. thanks.

Vent location is also different between different models/manufacturers of canopies. The placement of the vents is a design decision made along with a host of other design decisions, all of which can effect one another.

Years ago I saw an idea floated (not even sure if it made it to the prototype phase) for a canopy with airlocks on the nose and two sets of vents, one forward and one near the tail. The idea was that you could fly the canopy backward in a full stall and maintain pressurization. I'm not sure that the standard vent configuration combined with airlocks wouldn't serve just as well, but it's certainly an interesting idea.

Interesting idea, but wont recovery from that stall be pretty difficult? (if possible at all)

Why?

We're talking about one way valves here, not two way vents. I mis-spoke in my earlier post and typed "vents" which would imply a two way airflow.

If the valves themselves are well designed, I don't really see them interfering with the aerodynamics of the wing.

interesting concept. were the tail MDV's on the topskin of the canopy on the trailing edge?

Yes the vents were on the top skin. That way you could even fly it upside down

Bottom skin, if memory serves.

It would also be interesting to somehow design a "sharp" airlock that replaced the tail (but kept the airfoil intact).

So do vented canopies help on wall strikes after all?

it is a very generalized question. different people can define "help" differently.

feel free to review cliff strike videos and come to your own conclusions. (remember, it is your health at risk. make sure you are comfortable with YOUR choices, not someone elses.)

some claim a new design reduces the need for vented parachute.

back to your question as it relates to vid666's statement... if faced with a cliffstrike, do YOU desire a parachute that promotes more rapid inflation?

your call.

i just wondered if anyone has played with topskin tail vents in the sense that in a deep complete stall, flying your canopy backwards, would topskin tail vents allow air into a canopy and prevent a collapse while closing the bottom skin valves...............

topskin is the top surface of the canopy.
bottom skin is the bottom surface of the canopy, the part that you see when you look up.

are you sure you are using correct terms ?

Well, the way i see it, a controlled stall with vents near the tail would look something like this: (the pink circle is the vent placement)


And if you were to release the brakes all the way up, you'd get something like:

which would really make the landing a bit tricky

Then again, I'm no canopy constructor, i just like to theorize

I am loving the drawings as well

It seems like you are illustrating tail flutter, which typically happens when a canopy is flown on risers with the toggles floating free (i.e. not in the jumpers hands).

I don't understand how that changes with the presence/absence of a rearward valve system. Can you explain what you see the valve doing?

With a one way valve, when the canopy is pressurized, the valve is closed. So if the canopy is in flight (which, presumably it is when you are attempting to land), the valve is closed.

I would expect that with an airlocked canopy having rearward valves, the tail would actually stay more rigid and would be less susceptible to tail flutter.