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Inventing Freediving Luge

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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We pee deep. Ew!
Sep 24, 2002
Well, maybe "freediving" is not the right word, but this weekend, we invented a new game. We were grabbing large chunks of slate and using them for variable ballast dives. In one case, one of my buddies (who shall remain nameless, unless he wants to fess up) rocketed down using a rock that had to be about 35 kg. I think that we may post this profile soon.

The cool thing was that you could actually steer the rock and glide using your fins and the shape of the rock slab itself. Although this was really cool, we wanted more (being engineers and such).

So my question, to any aeronautically inclined DB fellow members, is whether it would be hard to build an underwater "luge/glider" that we could use to maximize our fun, and how would we go about designing it. We have access to stainless steel fabricating talent through two of our members, and it is pretty easy to get software that will generate a lot of standard foils if we need to create wings (I was thinking of NACA 0009 for this). We are hoping to make the sled in the 30kg range, so that we can carry it out on the water easily enough and power it up to the surface with a standard lift-bag or BC.

OK, thanks in advance for any replies
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Diving luge.

I was thinking about this thing the other day, and how to build it. I had an idea of making a hollow ss steel type of boogie board, sort of like the one that Jim and Jim were using for the depthfinder. Then mounting two ball valves by the handels, so you could open them both and the luge would fill with water and sink. I think that water is about 8lb per gal, so we would need around 2.5gal,I think. Then using a small Co2 gas cartrige to fill the luge , I'm not sure if this would work, but I wouldn't mind trying it out. At home I have a Co2 bike tube filler, that consist of a small trigger device that when pulled relleases the gas, I don't think I would have any problem adapting this to a ss. steal luge. It would sort of be a pain in the ass carrying a bunch of Co2 canisters around, but you never know.

Pony bottle?

Jim has a pony bottle so we could just use a primary regulator and a low-pressure valve for a BC to displace the water. Could even put 2 regs on the sled and use it as a rescue vehicle if needed. I have some 80cf bottles if we want more air.

Here's a profile with the 35kg rock. Average descent rate was 2 m/S, peak was abut 2.14 (sure seemed a lot faster!)
Somehow the attachment didn't post 1st time ...


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the luge

That poney bottel sounds good, that way we wouldn't have to change littel cartriges all the time. I was thinking that I might want to make the luge so that it is barley boyant in the water, and that it would take just a small amount of water to make it sink. It would a good idea to also add a fin going down the bottom center, so it would be easy to stear and to keep straite.
I'll make up a drawling tonight on paint shop, and send it,and see what you think of it.

Freediving Luge..
Sounds like you have been up to about the same stuff I in Italy.. the water there was cristal clear and I could see the edge in the water where the bottom dropped to about -50m from -2m and I had plenty of big rocks to use.. I did several dives quite deep.. and if you are still asking for advice.. I would say don't put too much weight into your thing.. as you are sinking too fast it is difficult to control, and the wings you were talking about wouldn't help unless they were massive..
So if my experience with rocks counts I would make it V-shape with wings, not too heavy though..

I found that rocks about 5kg were the best for my use as in the very beginning they were slow, but when down to about -20m it was more than enough pull--> hard to control...

Just my 2c

Let us know how your project comes along.. and.....dont dive deeper than you can dive without.. as technique can fail no matter what..
dive safe

Yes, I used mostly small rocks (the profile that I posted wasn't mine). I did dive with a large rock at least once and the water actually ripped it from my hands near the bottom.

The site that we dive is less than 0M, so not much chance of getting too deep to come back up, though I have to admit that a few times I looked up and was shocked how far down I was -- apparently the brain eventually calibrates that x seconds - y meters and in this case x seconds was about 2y meters.

That was a blast Friday with the "SledRock". The ironic part, is that the quarry we dove in could have mined "Bedrock", and now we have this cool new sport using "Sledrock". Dan, I had two other profiles that were 70', but the 75 pound rock landed me only at 61' on the slope. The speed through the water was actually greater than the profile indicated, but I was steering it not exactly straight down. There were sheets of rock debris flaking off and one of them pinned against my head and wouldn't budge free due to the speed, until I turned my head to the side to shake it. What a rush! On the ascent, I couldn't figure out why all of the 2 & 3" sized rock flakes were falling. I thought you guys were throwing stuff in. Then it dawned on me. I must have looked like a comet, with a debris trail.

Mike, I'm a little hesitant to equip the "metal boogie board" with a pony bottle, as it may need to be dropped in the event an ear clogged or something unexpected. Imagine what could happen if the K-valve hit a rock. We've got to figure out some sort of retrieval system.

Can't wait until we fabricate something more permanent, and can try the deeper stuff.

Till next dive,
hope im not too late for ideas...

what about making your wing almost neutral(slightly positive) and leaving room on the wing so that you would strap a rock (you seem to have access to plenty...:D ) to the sled, then when your at the bottom, ditch the rock (im sure you can come up with some nice quick release mechanism for doing so) and your on your way up with a positively boyant wing (you get to luge effect on the way up and on the way down...:t )

the box in the middle of the wing is where you would put the rock(s)

good luck

apparently i dont know how to attach an image...:duh
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Sorry mate, only just noticed this :)

Have you seen the big blue? Something like the NL sled they are using there? Throw me a PM/email (b.drew@adfa.edu.au) and I might be able to help you out.
Sounds great guys! Now all you need is an otto fuel engine and propulsor unit from a mk 48 torpedo, add some some passive sonar gear, maybe on or two spearguns.... :)

Seriously though, have you given any thought to propulsion? I know it kind of goes against the principle of having a luge, but imagine being able to power it back up from the depths. Perhaps a scuba tank with a special venturi could provide enough thrust! They fly pretty far out to sea when people accidentally drop something heavy on them and knock the valves off, (which I have NEVER done) so maybe they might have enough grunt to push you through a loop de loop. :D

Or does that only work in the movies...

Thin's idea is probably much more sensible though. Just make the sled really positive, and have a 20kg or so as a dropweight. Shoot down, shoot back up. Pardon me for getting carried away.:duh

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