How does weight or elevation affects the parachute stall?

[e.a.hernandez 0]

So let’s say I open at 10K, pull on toggles and let them go up as far as the guide rings will let me and then star pull down slowly. Let’s say I mark the break line with a sharpie (next
To the guide ring) at that point where if I pull just a bit more my parachute begins to loose lift i.e. the stall.

Now, let keep everything else the same and only change the weight. What happens with regards to the stall?

Does the stall point not change? In other words would the parachute just stall at a higher speed with increased weight and stall at lower speed with decreased weight with the actual point of the stall (or the mark of the sharpie) not changing at all? Would the same apply with altitude i.e. everything else the same and only changing altitude would the parachute stall at higher speed the higher the elevation and stall at lower speed the lower the elevation but the actual stall point (sharpie mark) being the same?

[Zlew 0]

I'm not sure about the sharpie mark...but I"ve never really believed in an absolute toggle input value as "stall point". I can stall my canopy at a variety of different toggle points depending on angle of attack, airspeed, time at a given input, what happened right before the stall etc. But I get your general idea.

This is conjecture...but, I don't think the sharpie mark will change much, but the true airspeed at which the stall happens will change. At higher altitude your full flight speed will be a higher airspeed (true airspeed...i think..ha), and your stall speeds will also be higher.

With more weight, your indicated airspeed will increase for full flight and for stall.

In the second case, you will probably also find the amount of time for the stall to occur in a deep brake configuration will be shorter than in the lower weight/loading situation.

[RiggerLee 61]

In theory stall speed should change with the square root of the weight and one over the square root of the density. You kind of have to look at an atmospheric model to talk about how density changes with altitude. A lot of it depends on what happens with the temperature and how it changes over altitude. The basic model assumes that the temp changes in certain ways as you go up through different regions. For instance I really need to find some better high altitude data for my model.

The reality is a little different. Talk to some base jumpers. You'll find that weight and wing loading actually do figure into break setting. With the larger canopies and deeper settings on opening we actually do get into the range where this becomes an issue. For instance a heavier guy can get away with a deeper setting on the same canopy then a smaller guy. If you're really interested go to basejumper.com and look for stuff written by Tom Aielo. He has his own bridge and he's had the opportunity to work with people setting up their own gear in his courses. He has compiled more data then any one I know.

Lee

Lee
[email protected]
www.velocitysportswear.com

[chuckakers 370]

e.a.hernandez

So let’s say I open at 10K, pull on toggles and let them go up as far as the guide rings will let me and then star pull down slowly. Let’s say I mark the break line with a sharpie (next
To the guide ring) at that point where if I pull just a bit more my parachute begins to loose lift i.e. the stall.

Now, let keep everything else the same and only change the weight. What happens with regards to the stall?

Does the stall point not change? In other words would the parachute just stall at a higher speed with increased weight and stall at lower speed with decreased weight with the actual point of the stall (or the mark of the sharpie) not changing at all? Would the same apply with altitude i.e. everything else the same and only changing altitude would the parachute stall at higher speed the higher the elevation and stall at lower speed the lower the elevation but the actual stall point (sharpie mark) being the same?

Good question...for John leBlanc.

Chuck Akers
D-10855
Houston, TX

[chuteshack 4]

dont forget to throw air density into the mix as well( ''skinny '''air vs ''Fat''
air)