Your mission: minimize drag

[frost 1]

Let me see if this will be of any help to you wondering minds:

Any physical body travelling through the air has drag accociated with that motion. Drag is defined as the force that opposes forward motion. Drag must be overcome by thrust in order to achieve forward motion. (of course OUR way to get thrust is the force of gravity)

There are several types of drag in aerodynamics: form, pressure, skin friction, parasite, induced, and wave. We as skydivers should probably worry about only two of them. The drag i was referring to in my previous post is called FORM drag. The skin friction and from drag combined is what's called PARASITE drag.

There is established formula to calculate the parasite drag. It is:

Dp = CDp x S x S r V(square)

Where:
Dp = Parasite Drag
CDp= Coefficient of Parasite Drag
S = Wing area
r = Air density
V = Velocity

From here you can see that it would be pretty easy to substitute the equation variables with real life values. You may have a hard time measuring some of them, but it can be done.

My brain is fried... can anyone do the math? :) I think the Dp of a 220 sq ft canopy will be higher then Dp of a 120 sq ft canopy.

Edited to add links (although they may not be very interesting):
http://142.26.194.131/aerodynamics1/Drag/Page4.html
and for those that want to get really technical about this calculation and scaling of a wing up and down
http://142.26.194.131/aerodynamics1/Drag/Page3.html#Reynolds%20Number

SoFPiDaRF - School of Fast Progress in Downsizing and Radical Flying. Because nobody knows your skills better than you.

[davelepka 4]

Quote

Drag is defined as the force that opposes forward motion. Drag must be overcome by thrust in order to achieve forward motion

Doesn't this reinforce my position?

We know that the WL are equal, so the thrust issue moot. I have shown several ways where the larger canopy and pilot will have a reduced amount of drag in realtion to the smaller canopy. Wouldn't this equal better performance?

I didn't read your links, but from what I know about the Reynolds number, it's an adjustment factor for wind tunnel testing where you can use a very small model of an airfoil to test its properties at
very high airspeeds without needing the tunnel to produce those speeds. My gut reaction to its application toward this argument is that the difference in size and airspeeds between a big and a small canopy are not significant enough to make those principals relevant.

[gus 1]

I'd agree with Tree, you're worrying unnecessarily. The only time you need to start modding your canopy to reduce drag is when your skills are so good that you're exhausting all posibilities to gain that extra few percent of performance. And there are very few people in the world who fall in to that category.

Gus

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