Has this test ever been done

[gainer 0]

I've read a lot on the forums that people say that a 170 loaded at 1.0 behaves differently that a 105 at a wingloading of 1.0. My big question is not on whether or not this is true but rather is how do you test this?

Ok here is the idea, take a few pilots all of diiferent body weights. and set up several test, say all on a 1.0 wing loading but on say 5 different canopies, ranging from a 230 to a 105.

The test is simple, do a turn, with a camera and a g-meter, the thing that measure the amount of g-force that is being generated. Do several turns, ex a 90 with a 1/4 brake, measure it, 1/2 brake 90 degree turn. The measurement is how long does it take to do the turn, what g's do you generate and anything else that you will need. You do this test on different wingloadings on different canopies, naturally all on a square/ elliptical/ cross-braced.

Now I know there are propably 50 holes in this test but is this test any good? Also has a test like this ever been done and what were the results. Something like this will hopefully show guys about the dangers of different canopies, particularly the smaller guys who fly 79 velo's at a wingloading of 1.9

Ian, if this post is in the wrong place please move it

[kameraflyr 0]

what are you intending to demonstrate by this test:
Your hypothosis.

[frost 1]

Quote

has a test like this ever been done and what were the results

it's like a theorem and an axiom - first one needs to be proven, the other one doesn't. Why prove or test an axiom, when it's self evident? Basic physics, shorter lines, smaller wing... less distance for any given point on the canopy or the pilot to travel in any given maneuver.

Quote

the dangers of different canopies, particularly the smaller guys who fly 79 velo's at a wingloading of 1.9

why particularly them and why danger of a 79 @1.9?

[kameraflyr 0]

*** why particularly them and why danger of a 79 @1.9?

He wants to prove why I still have your $2.00

[berchtoldaj 0]

I've got $1.50 says shatalov beats you at the farm meet...bark, bark

************
Watch out for planters.

[rhys 0]

Quote

Ok here is the idea, take a few pilots all of diiferent body weights. and set up several test, say all on a 1.0 wing loading but on say 5 different canopies, ranging from a 230 to a 105.

What would be the advantage of the conclusion?

You would know how many G's the canopy gave. At a 1.0 wingloading you would not be finding anything too interesting out, and wouldn't be explaining why a smaller canopy is 'whippier' than a larger canopy of the same wingloading.

It is an intersting topic though, my fiance has just got her new crossfire 89 and at 50kg (110lb's) she has a whopping 1.48 wing loading. if she wanted to compete with usual wing loadings she would need a;

69 square ft to have 1.9

59 sq/ft to have 2.2.

or carry weight on a smaller canopy to achieve that same W/L.

So I guess my question, and assuming the question of the OP is;

What difference in flight characharistics are there between a small pilot on a canopy (no added weight) with a W/L of 2.5 compared to a massive guy on a canopy with the same wingloading.

and if there is a difference (which I am inclined to believe thare is?) why is it so?

"When the power of love overcomes the love of power, then the world will see peace." - 'Jimi' Hendrix

[shropshire 0]

There are too many variables for a real conclusion to be made. What exactly is 1/4 brake? -
How do you ensure that the control input is exactly the same every time on every canopy?
How do you make sure that no weight shift input is used every time on every turn on every canopy?
How do you ensure that the air mass they are flying through is exactly the same?








P.S Oh glad you told me what a G-meter is

(.)Y(.)
Chivalry is not dead; it only sleeps for want of work to do. - Jerome K Jerome

[frost 1]

Quote

I've got $1.50 says shatalov beats you at the farm meet...

I dunno man... there are two things i've dreamed of ever since i was a little girl. One was to be on the centerfold of Parachutist. The other one is to beat Buechler. The first one has proven to be much easier than the second one. At least i still have something to strive for.

Quote

bark, bark

Tell Buddy i miss him.

[gainer 0]

What am I trying to demonstrate?
A 105 loaded at 1.0, like what does it react? a 135 loaded at 1.5, 1.7, etc. The point is I am trying to tell the person who has 200 jumps, who does not read Brian Germain's notes or articles that if he/she is intending to jump his 135 loaded at 1.0, that it would be like jumping a 150 loaded at 1.4, cause it makes more sense as we judge it on poeple who weigh 75 - 85 kg. Now we can get a better idea of a person who weighs 98 kg who jumps a 250 cause on a 230 his wingloading is 1.01 and he can't jump something smaller, and vice versa for the small pilot. My calculations are off.

"it's like a theorem and an axiom - first one needs to be proven, the other one doesn't. Why prove or test an axiom, when it's self evident? Basic physics, shorter lines, smaller wing... less distance for any given point on the canopy or the pilot to travel in any given maneuver. "

Yes I do agree that shorter lines give me ..., tell the pilot who dearly wishes to jump a 79 at a W/L of 2.0 Now because he has 1000 jumps and according to some chart, I think Brian Germain's, when you have 1000 jumps you can jump a canopy at a W/L of 2.0 ... It is these guys who I would like to show what they are doing.

"What would be the advantage of the conclusion?"
Just different data on different canopies, enablling you to cover a wider range

"There are too many variables for a real conclusion to be made. What exactly is 1/4 brake? -
How do you ensure that the control input is exactly the same every time on every canopy?
How do you make sure that no weight shift input is used every time on every turn on every canopy?
How do you ensure that the air mass they are flying through is exactly the same? "

This is where the 50 holes come in. 1/4 brakes is when you pull the brakes 1/4 of the way down, now 1/4 brake is just one toggle, other stuff is just a nother variable and when the test is done try and minimise these variables.

At the end of the day I want people who are on the high weight and lower weight spectrum to know what they are jumping with. I do not have the authority to stop the guy with 1000 jumps to jump a 79, because all the rules and charts say that he is allowed. I want to show that jumping a 79, loaded at 1.9/ 2.0 is the same as jumping a 96 at a wingloading 2.5. Now I think a lot of people will step back and make a better decision when downsizing from a 110 to a 79

[kameraflyr 0]

I want to show that jumping a 79, loaded at 1.9/ 2.0 is the same as jumping a 96 at a wingloading 2.5.

[frost 1]

Quote

Now I think a lot of people will step back and make a better decision when downsizing from a 110 to a 79

Downsizing from a 110 to a 79 is a bad, bad idea, 31 sq ft that's a HUGE drop in canopy sizes, especially when you go sub-100. No matter how many jumps that person has 1000 or 10000, they should follow a gradual downsize pattern, not skip 4 sizes! Someone doing that will have little to learn from the comparison of flight characteristics. They will have their hands full trying to save themselves and not hurt someone else. I personally dont think they will follow basic safety recommendations or listen to your good advice, people that make decisions like that are usually the types that dont listen to the voice of reason or experience.

[kameraflyr 0]

I couldn't agree more. If someone is foolish enough to ignore the advise of the masses and downsize that agressively, it is unlikely that they will listen to any reasoning regardless of how scientific it's basis.

[amir1967 0]

Quote

I've read a lot on the forums that people say that a 170 loaded at 1.0 behaves differently that a 105 at a wingloading of 1.0. My big question is not on whether or not this is true but rather is how do you test this?

Ok here is the idea, take a few pilots all of diiferent body weights. and set up several test, say all on a 1.0 wing loading but on say 5 different canopies, ranging from a 230 to a 105.

The test is simple, do a turn, with a camera and a g-meter, the thing that measure the amount of g-force that is being generated. Do several turns, ex a 90 with a 1/4 brake, measure it, 1/2 brake 90 degree turn. The measurement is how long does it take to do the turn, what g's do you generate and anything else that you will need. You do this test on different wingloadings on different canopies, naturally all on a square/ elliptical/ cross-braced.

Now I know there are propably 50 holes in this test but is this test any good? Also has a test like this ever been done and what were the results.
Ian, if this post is in the wrong place please move it

Good Q that I would like to get answer too.
Let say we go with 2 jumper hi hop flying side by side one on 170@1.0 en second 135@1.0 .what is the speed sink rate do 180 hom much hight is lost and so on.
At one point they are the same or or 170sqf has to put some weight let say @1.2 and test again.
Is that been tested and if where I can read about it.
*** ps*** 8 years in the sport 550 jump alot of blaa,blaa,bla and never answer to simple question
Please

Amir

AM67

[kameraflyr 0]

The full answer to your question is far to lengthy for this forum but the short (over simplified) version is:
Two canopies: Same design, different proportions
longer line lengths = longer pendulum effect, longer recovery. (inverse is also true)
larger canopy= more drag, but also more overall recovery from dive and turn due to increased surface area. (inverse also true)
These two seperate effects of downsizing are inversely exponentional to themselves. (fancy way of saying that the smaller/larger the sizes do not increase or decrease recovery or drag at a linear rate, it increases much more on the ends of extremity)
Using your example 170 vs. 135 (all other things being equal) Both canopies will share the same designed glide slope, the 135 will be faster due to reduced surface area and drag, faster turn rate due to shorter distance betweeen point or rotation and point of anchor, faster recovery to wings level flight due to same effect; but, longer overall recovery to original glide slope to reduced surface area.available.
Others please chime in if you can give a better explaination.