Closed nose canopies vs airlocks

[RichM 0]

The current discussion on airlocks led me to wonder just how effective as an airlock mechanism are the closed nose designs seen on high performance canopies such as the Velocity, Xaos, etc?

Rich M

[amir1967 0]

I may have it wrong, but after the canopy has inflated no more air can go in so closed nose air-locks or open should not make much of a different
(is like driving in a car with only one window open, not too much wind come in, almost like it was closed.
Now if the nose is sharper (not as thick as the rest of the canopy maybe that will make grater difference in performance ? )
Amir

AM67

[VectorBoy 0]

I guess you can include the crossfire into that group also. It has a semi closed nose to. Any other non-crossbraced canopys with semi closed noses out there?

[SkymonkeyONE 4]

There are plenty. The Flight Concepts Rage looks a LOT like a Crossfire 2. Also included are the Competition Cobalt and the Fandango.

[johnny1488 1]

besides the closed nose design Icarus builds every canopy with a constant cell aspect ratio to better keep the cell pressurazation constant across the airfoil. I think that would have more to do with stability. I think the formed nose is there to control the openings and keep distortion of the nose to a minimum like x braces do for the entire wing.

Johnny
--"This ain't no book club, we're all gonna die!"
Mike Rome

[kallend 2,131]

Quote

besides the closed nose design Icarus builds every canopy with a constant cell aspect ratio to better keep the cell pressurazation constant across the airfoil. I think that would have more to do with stability. I think the formed nose is there to control the openings and keep distortion of the nose to a minimum like x braces do for the entire wing.

It's not immediately obvious to me how cell aspect ratio relates to pressurization. Can you elaborate?

...

The only sure way to survive a canopy collision is not to have one.

[johnny1488 1]

From what I understand, (Im not a physicist nor a canopy designer) when you taper the leading and or trailing edges of a canopy, you affect the cell pressurization. The shorter cells moving at the same speed as the rest of the canopy is going to have a greater air pressure. Icarus scales the height and width of the cells in proportion with the change in chord to keep the aspect ratio constant across the planform. One example that stands out in my mind was a video of someone on a stilleto finding the stall point. It seemed that the center of the canopy started colapsing long before the end cells lost their shape. I have flown my Icarus canopies in turbulence in which other canopies were doing the old "accordian" as jumpers came in to land. I've seen video of my canopies that showed little or no sign of this practice under the same conditions. I believe this also lends itself to Icarus canopies having a longer control range and toggle stroke than many other canopies.

Johnny
--"This ain't no book club, we're all gonna die!"
Mike Rome