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My question is: Is the stall independent of the wing loading?

So far from what I have read on Aerodynamics the stall is only affected by the angle of attack.
Increasing the wing loading will increase the speed of the parachute. However, if stall is only affected by angle of attack shouldn’t the wing stall regardless of wing load once this angle of attack is exceeded?

So say I have a jumper with break settings right at the stall. Assuming everything else is the same if this same jumper starts adding weight shouldn’t the parachute still open in a stall regardless of the weight?

The critical angle of attack at wich the wing stalls is independant of the weight. It is dependant on the shape of the wing.

Stall speed increases with the wingloading.

So assuming everything else stays the same, a canopy just over the stall speed will stall if you increase the weight enough.

Adding more weight will increase the stall speed but the critical angle should not change. If the wing is at an angle that does not cause a stall I thought adding more weight will increase the speed of the wing but should not necessarily stall the wing if critical angle does not change. Does adding more weight then changes the angle of attack on a parachute?

Yes, but when you increase the weight, you also increase the speed, so everything else cannot stay the same.

There was a huge discussion about this a while back in another thread. I'd suggest digging it out and reading it.

There was also a lot of discussion about the meaning of the term "stall" and whether we were discussing a wing that was not generating lift at all, a wing that was not generating enough lift to be useful in our context (in the real world) or a wing that was deflated and falling.

I went out and did some testing with a weight vest after that discussion, and my conclusion was that adding weight did not stall the canopy. It can make the canopy sink out a bit at opening (because you're generating less lift per suspended load, maybe?) but it doesn't enter a classic parachutal stall.

I also suspect that the reactions of the wing in these situations will be different for different wing forms.

Basically, I think this isn't an issue where aerodynamic textbooks don't help us much.

The most important thing to do is to get real world experience under your own canopy, especially immediately after opening from a safe object, to determine what it will do.

The angle of attack is the angle between the chord of the wing and the relative wind. The critical angle never changes, but the AOA does change all the time.

More weight means the wing needs more lift to fly, so the stall speed increases.

Being a glider, adding weight to a canopy it increases it's speed.

Tom, I agree with everything you said.

A BASE canopy is much more complicated to understand as it is a glider, the shape of the airfoil can change a lot, and being a very stable wing at or near stall speed, a stall is not as violent as a normal wing and can actually be controllable during the stall, making the definition of stall more difficult.

Thanks for the replies. I was curious also as to what happens when wing loading increases as result of elevation change. Say you have a break setting that slow you down enough and does not stall parachute. You then jump a higher elevation, which will increases your forward speed since equivalent to wing load increase. In this case do you keep adjusting to deeper break settings to slow down the flight? Wouldn't there be a point where you have to up size your canopy as the only way to get to a break setting that slows you down enough and does not stall the canopy?
As Tom said it is best to experiment in a controlled environment as much as possible...but I am just curious as to what has been tried and data gathered...

I'm not sure I understand.

How would field elevation change wing loading?

Sorry Tom. Wing loading does not change since neither the total weight nor the area of the wing changes. What I mean is the wing will fly faster as you increase the altitude (which I was taking as equivalent to an increase in wing loading if altitude does not change). Not sure my analogy applies very well since altitude also changes air density. But either way would the change in speed be so substantial that setting, for example, a deep break that works ok at Twin Falls not work ok at 4000 ft higher. In that case would you keep setting a deeper break setting or would that stall the parachute unless you go to a bigger size?

I'm pretty sure that density altitude doesn't change the stall point of the wing. At least that was the upshot of a conversation I had several years ago with a guy who's forgotten more about parachutes than I'm likely to ever know.

What about the speed the parachute flies at in a deep break setting? Would the parachute fly faster with same deep break setting and wing loading in less dense air? Let's say it does fly faster...would this "faster" mean faster enough that it would make a substantial difference in case of a 180 opening at a higher altitude (assuming the deep break setting was set at sea level). I am pretty sure this is a stupid question I am asking that would not matter much at a practical level and I would not be asking if I had more experience.

The ground speed will go up with altitude, so yes, in relation to the ground, the speed will increase. And yes, this will make a difference in how how much altitude will be lost and distance, in relation to the ground, travelled during turns and flares. It is not the same as increasing wing loading because as far as the parachute is concerned the same amount of air is flowing over the wing, the airspeed is the same, only the ground speed is faster.

For wingloading, the greater the weight, the greater the force of gravity so the faster the wing will fly. The angle that the wing will stall is the same, but the speed goes up with weight. This is because of the speed generated by the increased wingloading lowers the angle of attack necessary to achieve a similar glide angle of lighter wingloadings.
But, because airspeed also pressurizes the wing and creates a rigid wing, as airspeed goes down, the internal pressure is less, and the wing becomes soft, loses shape, and loses performance. The wing also becomes "parachutal" In that it relies more on bottom skin inflation similar to a round parachute, than on lift generated from lift produced by airflow over the topskin. This also depends on the design of the wing, some wings will be stable while other will depressurize enough to collapse.

You sure about that?

Weight is the force of gravity pulling on an object, no? Enlighten us all, Sir Isaac Frey.

Copied and pasted to the CalTech JPL forum just for laughs…no offense.
http://www.rocketryforum.com/...ropulsion-Laboratory

Well basically, yes. Although not stated as clearly as I could have.

http://en.wikipedia.org/wiki/Weight

And I am wrong about airpeed, although if your in a plane the airspeed indicator will indicate the same airspeed. The true airspeed is higher as well as ground speed. Here is a good starter.

http://en.wikipedia.org/wiki/Density_altitude

Going off of that, the internal pressure of a parachute will be less at altitude also...

Yea, I appear to confused about how wing loading effects angle of attack and airspeed. So, speed goes up because of increased weight, but it does not change the angle of attack.

This about paragliders, but very interesting.
http://www.skynomad.com/...les/wing-loading.htm