Improvised physics instruments for a jump

[BlindBrick 0]

I have a science of sport performance class that I'd like to gather some data from a jump for. I figure I can bum a Pro-track or Neptune for distnace and speed data, but I'd really like to get some info on acceleration and G loading. Unfortunatley my college doesn't have any instrumentation that they think might be of use to me. So, i was wondeirng if anybody had some ideas for some improvised gear. It doesn't need to be super-accurate, but I would like to be at least in the ballpark.
Besides being easy to make, ideally it would be relatively easy to read in flight and equally easy to minimize snag points on.


-Blind

"If you end up in an alligator's jaws, naked, you probably did something to deserve it."

[Hazarrd 1]

pm sent. if anyone else needs this info i did an extensive research project on this.

.-.

[diablopilot 2]

http://www.g-labs.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=GSOS&Product_Code=G&Category_Code=


Here you go....might be the ticket you need...

----------------------------------------------
You're not as good as you think you are. Seriously.

[mjosparky 4]

Quote

http://www.g-labs.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=GSOS&Product_Code=G&Category_Code=


Here you go....might be the ticket you need...

JP,

That little thing looks neat. I might have to get one.
Sparky

My idea of a fair fight is clubbing baby seals

[diablopilot 2]

Might have one sitting around you could look at.... next time you're at the DZ let me know and I'll see if it's still at the store....

----------------------------------------------
You're not as good as you think you are. Seriously.

[mjosparky 4]

Thanks!

My idea of a fair fight is clubbing baby seals

[kelpdiver 2]

Quote

http://www.g-labs.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=GSOS&Product_Code=G&Category_Code=


Here you go....might be the ticket you need...

So what's with the one axis bit? Is that hard to use in practice in 3 dimensions?

The price sure is nice.

[darkwing 5]

The G*spot looks like a good option for you, I think you could get away with two of them, but three would be better. They need to be mounted perpendicular to one another. The technical details of the G*spot are important though. What is its time and g resolution?

If you have some electronics experience you could buy a single chip accelerometer and kludge up a recording unit yourself. The chips were inexpensive the last time I checked (which was a long time ago)

Edit to add: In a brief review of its operation it seems that it records max g's, not acceleration as a function of time. It is a much less useful instrument than I originally thought.

-- Jeff
My Skydiving History

[quade 4]

Quote

So what's with the one axis bit?

I'm guessing you don't know a whole lot about G-meters in general. Most G-meters are single axis and for most uses . . . that's just fine. For instance, the G-meters in most aerobatic aircraft are only single axis. Of course, most of the older ones are mechanical (basically a spring scale) and it would really be too complicated/expensive to built mechanical multiple axis meters.

That said, if you're building electronic ones, it's only slightly more complicated to make one using multiple sensors and get software to figure out the vectors, but it -will- cost more -- at least three times more. Even at that, you'd still have to mount the thing carefully for the reading to be reasonably accurate.

The advantage of a single axis unit such as the G-Spot is that you could just wear it on a necklace tucked inside your jumpsuit and it's going to give fairly reasonable readings for opening shock because the unit would sort of automatically align itself along the force axis.

quade -
The World's Most Boring Skydiver

[kelpdiver 2]

Quote

Quote

So what's with the one axis bit?

I'm guessing you don't know a whole lot about G-meters in general. Most G-meters are single axis and for most uses . . . that's just fine. For instance, the G-meters in most aerobatic aircraft are only single axis. Of course, most of the older ones are mechanical (basically a spring scale) and it would really be too complicated/expensive to built mechanical multiple axis meters.

I have non skydiving problems I've thought about solving, but I'm not really a circuit guy. Just trying to imagine how many problems this device is a solution to. GPS receivers would allow more, but the precision, esp in the altitude, is not very good at the speeds I'm concerned with.

[mjosparky 4]

Quote

Quote

Quote

So what's with the one axis bit?

I'm guessing you don't know a whole lot about G-meters in general. Most G-meters are single axis and for most uses . . . that's just fine. For instance, the G-meters in most aerobatic aircraft are only single axis. Of course, most of the older ones are mechanical (basically a spring scale) and it would really be too complicated/expensive to built mechanical multiple axis meters.

I have non skydiving problems I've thought about solving, but I'm not really a circuit guy. Just trying to imagine how many problems this device is a solution to. GPS receivers would allow more, but the precision, esp in the altitude, is not very good at the speeds I'm concerned with.

Does anyone have any idea what he is talking about?

My idea of a fair fight is clubbing baby seals

[quade 4]

Most of the current, even -really inexpensive- hand held GPS units will record a track, so you'd have 3d data plotted against time (well that's 4d really isn't it?). The issue is they usually only sample at 1 second intervals, so the resolution isn't all that great if you wanted to do G force calculations. The complexities of the math mean that you'd end up with data accurate to about 2 seconds, so for sustained accelerations you might be ok, but for something like canopy openings . . . no good for anything other than the most gross average over those two seconds . . . no real opening shock values.

quade -
The World's Most Boring Skydiver