0

## Recommended Posts

The title says it -- in the US, we use lbs/sq.ft, which is, of course, meaningless in metric countries. But since most canopies are manufactured by US companies, and sized in sq. ft., does this mean that it's generalized to the rest of the world?

And if so, does that mean that sizes have a more arbitrary feel to jumpers in metric countries?

Mostly curious, but if it means a more arbitrary feel, maybe it's not the best approach

Wendy P.
There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

##### Share on other sites
As canopies are design and sized in sq ft, i use and got used to sq ft to calculate the wingload and everything else like canopy sizes, etc, etc.
I think everyone uses and understands better in sq ft regardless of being in a "metric country".

##### Share on other sites
That was my thought, too. Just wondering if therefore wing loading is given a little less attention where its calculation isn't a simple matter estimated in about 1/2 second, but instead an arbitrary pain in the ass.

In such a case, "my buddy is using the same canopy and he's not that different a size" sounds a whole lot easier to calculate

Wendy P.
There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

##### Share on other sites

Yes, definitely more arbitrary at least at my level at least at our DZ. An instructor recently asked for my weight "in trunks", then said "ok, 170 would do at your experience", I said "thanks, I weighed myself in gear and my exit weight is 99kgs, which is nearly 218 lbs, so I don't want to rush to near 1.3 wingload", he was like "O_o mkay, you have a point". On the other hand I once heard the S&TA said to a visiting jumper "I cannot allow you to jump a canopy at this wingloading at the DZ". So maybe starting at some level they do pay attention to exact numbers.

Buddies mostly don't know their WL and I often have to remind them that they're flying their 170s at approx the same WL as I fly my 190 so they shouldn't tell me how easy it's to land a 170 and how soon I should be jumping the same

As the sizes of the canopies go, we use sq.ft. everywhere for ram air (yes, rounds that are manufactured in Russia are still in m^2). Won't speak for everyone, but for me yes, 190 is just a number, however now I will convert it and try to remember it in metric system just in case.

##### Share on other sites
doesnt feel that way here in oz, in my case it was well covered off in ground school, we where also given a conversion sheet and the wingload \ downsize guide. Also well covered in canopy courses etc.

I think we are generally ok with the metic \ imperial conversions being taught at school, I assume the teach the reverse in the US ?

##### Share on other sites
The conversion to lbs is easy enough to sort out.
Have you seen my pants?
it"s a rough life, Livin' the dream
>:)

##### Share on other sites
Quote

I think we are generally ok with the metic \ imperial conversions being taught at school, I assume the teach the reverse in the US ?

A meter is like...a yard, who knows what a kilogram is, my soda comes in liters, and why does the bank say it's 23 degrees out?

##### Share on other sites

why the united states system is retarded http://i.imgur.com/huhvM.jpg

Spank the

##### Share on other sites
Quote

Quote

I think we are generally ok with the metic \ imperial conversions being taught at school, I assume the teach the reverse in the US ?

A meter is like...a yard, who knows what a kilogram is, my soda comes in liters, and why does the bank say it's 23 degrees out?

I thought the Rule was 45 degrees.

##### Share on other sites

Wendy P.
There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

##### Share on other sites
Quote

why the united states system is retarded http://i.imgur.com/huhvM.jpg

I take exception to "retarded".
We are NOT retarded....we are sly devils.

The system we use was built to confuse the rest of the world. It works as designed.

My reality and yours are quite different.
I think we're all Bozos on this bus.
Falcon5232, SCS8170, SCSA353, POPS9398, DS239

##### Share on other sites
Quote

An instructor recently asked for my weight "in trunks"

Actually, conversion to trunkified weight (a/k/a trunkification) is quite easy. As shown HERE, 1 trunk equals about 140 kg. So let's say you weigh 170 lbs. That converts to about 77 kg., or 0.55 trunk.

##### Share on other sites
Simple mnemonics for metric weights and measures:

A metre measures three foot three - it's longer than a yard, you see.

Two and a quarter pounds of jam weigh about a kilogram.

A litre of water's a pint and three quarters
Atheism is a Non-Prophet Organisation

##### Share on other sites
It's one of the stupid aspects of skydiving (and aviation in general). Even though we do everything in metric here, skydiving related stuff is still imperial. And yeah, it somewhat works, although I won't be able to tell you the size of my canopy in square meters, nor my wingload in kg/m^2.

##### Share on other sites
Quote

Even though we do everything in metric here, skydiving related stuff is still imperial.

Do you measure altitude in ft?

##### Share on other sites
Quote

Quote

Even though we do everything in metric here, skydiving related stuff is still imperial.

Do you measure altitude in ft?

Nope. 4000 meters it is !

##### Share on other sites
That's the point, skydiving is all in imperial measurements.
Everyone thinks and talks in ft, lb, etc !! The conversion from kg to lb is easy enough and concerning altitude, well, i myself prefer to think in ft not meters .....

##### Share on other sites
Quote

That's the point, skydiving is all in imperial measurements.
Everyone thinks and talks in ft, lb, etc !! The conversion from kg to lb is easy enough and concerning altitude, well, i myself prefer to think in ft not meters .....

Exactly. I can jump at 14000ft, or 4000m. Why would I cheat myself out of all that extra freefall time?
You are playing chicken with a planet - you can't dodge and planets don't blink. Act accordingly.

##### Share on other sites
I live in Sweden. We skydive using meters for altitude, while our neighbors in Norway use feet for some reason. It may be that they don't have their own association but are part of Luftsportforbundet (Air Sport Association) and have inherited more from other flying sports than we have in Sweden. Or I may be wrong.
In any case, in both countries we use ft^2 for canopy sizes. In both countries we have a table (one in Sweden, another in Norway) showing the minimum allowed and recommended size (in ft^2) of canopy, with regard to exit weight (in kg) and number of jumps. Because this table exists and is part of our basic rules, wing loading in actual numbers (lbs/ft^2, or kg/m^2 or combinations of the above) are not often calculated or discussed.

##### Share on other sites
IJskonijn

It's one of the stupid aspects of skydiving (and aviation in general). Even though we do everything in metric here, skydiving related stuff is still imperial. And yeah, it somewhat works, although I won't be able to tell you the size of my canopy in square meters, nor my wingload in kg/m^2.

Exactly ... i also cannot tell whats my wingload in kg/mt ...

##### Share on other sites
Wendy,

Most canopies are in sqfeet. So, it is my weight, plus other weight, x2.2...... The rest is the same.

Not so much of a pain, and we follow wingloading quite well as a rule of thumb.
You have the right to your opinion, and I have the right to tell you how Fu***** stupid it is.
Davelepka - "This isn't an x-box, or a Chevy truck forum"
Whatever you do, don't listen to ChrisD.

##### Share on other sites
A quick bit of maths tells me that if you divide your WL in kg/sqm by 5, you'll get near enough your WL in lb/sqft (to within 3%)

##### Share on other sites
Jalien

A quick bit of maths tells me that if you divide your WL in kg/sqm by 5, you'll get near enough your WL in lb/sqft (to within 3%)

... but you don't know your canopy in sqm, do you?

##### Share on other sites
In the UK everyone's essentially bi-lingual when it comes to measurements as metrification wasn't that long ago, is far from complete and still ongoing on a rolling basis.

The weights and measures we use in everyday life are a complete hodge-podge. We buy petrol in litres but cover distance in miles and then work out our petrol consumption in MPG. Engine sizes are measured in ltrs but power output is in BPH. Milk and beer is still in pints but coke comes in ltrs. We tend to weigh ourselves in stones but bake in lb. and oz. though we buy the ingredients in kgs. We state our height in ft and inches but everything else is measured in metric, except distance in miles and the size of land in acres. Strawberries come by punnet. Ale can be bought by the yard. A pound of gold weighs less than a pound of lead while an ounce of lead weighs less than an ounce of gold. We like to fuck with people.

This means most people are pretty happy converting between two, even switching from one measurement to another on the same task. I might buy 2x4 lumber specifying its length in meters for example.

For wing loading you either know your weight in pounds or convert from stones by multiplying by 14. The size of the canopy in sq ft is happily understood even though we'll pack on a tarp bought in meters squared.

Our botch job of a system (which will probably be fully metric in another 50 years) is probably even more confusing to outsiders than the seemingly random US system. It does mean though that we can use virtually any measurement interchangeably and either convert at will or just mix and match and overlook any incongruity.

##### Share on other sites
SA is a metric country but when it comes to skydiving everything is in feet and lbs

Plus 10000ft sounds more impressive than 3000m to a whuffo

Only time it is an issue is when working out WL i have to think more than I would like to get from kg to lbs

## Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.