Question on canopy size and loading

[weber 0]

My question is what is the difference between a 210 lb. person flying a 210 square foot canopy or a 135 lb. person flying a 135 square foot canopy of the same make and model. I understand the length of the lines affects the turning speed and reaction time, but is there more to it? I heard once that the size of air molecules stays the same no matter how big or small the canopy is and this is why the 135 lb. person would have a faster decent rate if the two were side by side going straight. Thanks for any input.

[Zennie 0]

I'm no expert by any stretch, but I was having a conversation with my rigger along these lines just the other day.
Basically, to make a long story short, the 135 lb person loaded at 1:1 presents less surface area to the air ... both in terms of his//her body and the smaller canopy. Thus there will less drag on his 1:1 loading than the 210 pound person. The smaller person will therefore experience "hotter" performance even though the loadings are the same.
"Wear the grudge like a crown. Desperate to control. Unable to forgive. And we're sinking deeper."

[jfields 0]

I can't believe anyone beat Skybytch to this post, considering the title. Unbelievable! Justin
My Homepage

[skybytch 273]

rofl! Well if I hadn't had to actually do some work between 9am and noon this morning I mighta been first...

pull and flare,
lisa

[Fab 0]

Hello weber,
Although I'm a newbie I would just like to say the size of air molecules has nothing to do with flights charasteristics of a parachute. A molecule is a collections of certain atoms which forms a substance (oxygen for instance). You can't change it's size (with a parachute)
The bigger the canopy is the more lift you would have. I don't know if the 135 lbs person would descent faster then the 210 lbs person. That depens on the charasterics of the chutes they're using..
You have to see it like this...Gravity pull at a person at a constant force...(Force down= mass of person * 9.81)..that's easy...
However, a chute pulls the person up with a force which will depend off the mass a person, shape of the canopy, size of the canopy, altitude and downwords speed and some other variables i forgot. This could look like Force up = mass of person * square root of down_speed * size parachute to the power of two or whatever..
A leighter person would have a lower down force (so is decending slower) but also a lower up force because he (or she) is flying a smaller canopy (which means the person if descending faster). Which force wins the match...who shall say....Different chute's will have different descent rater..
I one don't agree with me..please ..let me know...I can be wrong because I'm a soooooooo new at this sport :)...

[FallingMarc 0]

Taken from Craig's post over in G&R in response to my asking this same question...
-------------------
Taken from the PD website under the link "Seminars" "Wing Loading and it's Affects"
FYI their use of "proportionally scaled canopies" is as follows:
"jumping a small canopy at your normal exit weight, and then jumping a much larger, scaled
canopy, with enough extra ballast so that the wing loading is the same."
C. Some reasons for differences in performance between large and small
canopies:
1. Turns: In general, the smaller the canopy, the shorter the lines. Its true that
two proportionally scaled canopies may have similar full glide speed at the
same wing loadings, but they turn very differently. The big canopy, with its
long lines, has relatively sluggish reaction to the controls, and the small
canopy has relatively quick reaction to the controls. This is due to the fact
that the large canopy must move the jumper a much greater distance out to
the side, in order to achieve a certain bank angle needed for any given turn
rate. This means that the smaller version of a canopy will feel much more
agile, even if flown at the same wing loading.
2. Flaring: A dynamic flare is one that results in a change in flight direction
from a descending path to one parallel with the ground. This requires a
change in the angle of the canopy, when viewed from the side. (Initially, the
amount of the angle change is about equal to the angular change of the flight
path.) This angle change is accomplished using toggle a movement that
causes the jumper to move out in front of his natural hanging place under the
canopy. The long lines of a big canopy require the jumper to be moved a
greater distance out in front to achieve the same angle. Shorter lines mean
that the jumper doesn’t need to move as great a distance forward to achieve
the same angle. This means the toggle movement must be more aggressive
on the larger canopy, compared to the smaller canopy, even at the same
wing loading.
3. For similar reasons to those above, the smaller canopy will also dive more in
hard turns, when compared to a larger scaled canopy, even when flown at
the same wing loading.
------------
Blue sies,
Marc

[freeflir29 0]

That there shit is purty interestin! Never really put any thought into it. I haven't pondered the differences in velocity of a coconut laden and non-coconut laden African swallow either.......but none the less interesting....."There once was a man named Enis....."-Krusty the Clown
Clay

[FallingMarc 0]

"This is all very interesting... tell me again how a goat's bladder can be employed to prevent earthquakes..."

[billvon 3,088]

> Basically, to make a long story short, the 135 lb person loaded at 1:1 presents less surface area to the air ... both in terms
> of his//her body and the smaller canopy. Thus there will less drag on his 1:1 loading than the 210 pound person. The smaller person
>will therefore experience "hotter" performance even though the loadings are the same.
If that were true, then freeflyers would all have slower landings than RW teams - floppier suits would mean more drag. In reality, the canopy and its line contributes 95% of the total drag the system sees, so the jumper has only a minor effect. It can help a little (i.e. pulling your legs up and getting your arms in can help your glide a bit) but you won't see a huge difference between a large and a small person.
-bill von

[billvon 3,088]

>You have to see it like this...Gravity pull at a person at a constant force...(Force down= mass of person * 9.81)..that's easy...
> However, a chute pulls the person up with a force which will depend off the mass a person, shape of the canopy, size of the canopy,
> altitude and downwords speed and some other variables i forgot. This could look like Force up = mass of person * square root of
>down_speed * size parachute to the power of two or whatever..
It's easy to figure out how much lift force a parachute system generates. If you survived the landing, then it generated lift equal to your exit weight. If it didn't, you would accelerate either up or down until you either left the atmosphere or hit the ground. A functioning parachute will always seek the speed that allows it to produce enough lift to exactly balance your weight - the definition of stable flight.
The only time lift changes is when you intentionally (and temporarily) change lift and speed with the toggles. This doesn't last long, but can be very useful for temporarily increasing lift for landing, or decreasing it for initiating a steep turn.
-bill von

[Fab 0]

of course...you're right....why didn't i think of that...was pretty late when I posted that i think.
Thanks :)

[wingnut 0]

now another question to ponder for ya.........
if we let little kids skydive what would the smalest chute that they could use be? take for example if my 7 year old cousin started to skydive and had lets say 1000 jumps before he was 10, and a 10 yearold might weigh 70 pounds could he jump a cobalt 40 and get a longer swoop than some of the biger guys cuz he would have les air reisitance but still be loading the canopy at 1.75:1 ????? oh wait this is crazy,, who would let a 7 year old jump......now if we got that ahh,,, veritically chalanged guy jtval met maybe we could do it.......

"up my noooossseee"- wingnut, at first euro dz.com boogie

[billvon 3,088]

>if we let little kids skydive what would the smalest chute that they could use be? >take for example if my 7 year old cousin started to skydive and had lets say
> 1000 jumps before he was 10, and a 10 yearold might weigh 70 pounds could he
> jump a cobalt 40 and get a longer swoop than some of the biger guys cuz he
> would have les air reisitance but still be loading the canopy at 1.75:1?
Things don't scale like that. John LeBlanc gave a talk on this at PIA 2001, and basically you can never make assumptions that equate things in parachute flight (i.e. 1.75 to 1 is _not_ the same when applied to a 70 pound jumper and a 200 pound jumper.)
It has been my experience in general that smaller people get better perceived performance from smaller but equally loaded canopies (due to the shorter lines, I believe) but shorter swoops.
>oh wait this is crazy,, who would let a 7 year old jump......
Two rather well known DZO's come to mind . . .
-bill von

[skymedic 0]

Quote

Two rather well known DZO's come to mind . . .

Well I know one would involve a little kid named Rook but I dont know what the other one would be?
Marc
Because I fly, I envy no man on earth

[wingnut 0]

a 7 year old solo or tandem? there is a BIG differance!!!!!

"up my noooossseee"- wingnut, at first euro dz.com boogie

[Fab 0]

anyone who would let a 7-year old jump solo is mentally disturbed...but I don't think that would happen anywhere

[skymedic 0]

I know wingy....I wouldnt put it against that certain midwest DZ to do something like that...ya know...
Marc
Because I fly, I envy no man on earth

[PhreeZone 20]

The other one runs a DZ, is on the BOD of the USPA, but neither of his DZ's are USPA members...... And he has one kick ass King Air, That should be enough hints for this one......
A rainy day at the DZ is better then a Sunny day at work

[skymedic 0]

I had a feeling that mighta been the other one
Marc
Because I fly, I envy no man on earth