I was in the Mount surf shop and museum yesterday and had my first up close look at a Turbo tunnel fin. . …
guess what ? (haven’t heard anyone mention this here before). . . .
The exit is smaller in diameter than the inlet !. . . . in other words they constrict the water flow !. . . . that’s REALLY stupid (and might explain why Bill keeps mistakenly saying that MY tunnels constrict water flow, which they DON"T !!).
Obviously constricting the water flow creates useless drag, and also reduces the ability of the tunnel to handle high angles of attack. . . it’s just a no brainer !
It seems likely to have that purpose, to enhance hold when noseriding–the annular tunnel being sized such that the lift component would be minimal seems to suggest that its purpose is to enhance hold, and a flow through a smallish decreasing annular with a vorticulationalarized (sorry–what’s the right word there?) low behind the annular would do that in a fairly inoffensive way, wouldn’t it?
Pssh–I dunno. (Was looking at some stuff on denticles and Speedo and the US Navy a minute ago though Roy, but haven’t the energy to post on the other thread–pm me if you want.)
in aero dymnamics the jet engine has a smaller opening on the back to push the air out faster making the airplain flying faster
i am no expert but i think they were going for the same thing with the fin
The thing about jet engines though is the turbine forces air out the back of the fin whereas with the turbo tunnel theres no turbine forcing water through the tunnel. I’m not sure what the science exactly is behind the tunnel, but it definitely seems like it would have greater drag than a regular fin.
I’m no expert on these matters. That being said, maybe speed wasn’t their goal.
Slowing the board down to keep the tail in the pocket would help with nose riding, as well as their jetamajigger whatever (yes, that is a technical term) that supposedly helps too. Not everyone is trying to break the sound barrier Mr Bloke. :0)
I say…when you’re going for an old school style, keep it old school.
There seems (I skimmed) to be no mention of the tunnel taper in Bob Bolen’s patent write-ups (http://www.google.com/…;btnG=Search+Patents) and the drawings don’t show any obvious entrance/exit difference (tough to be certain - Google doesn’t seem to have the drawing manipulation part of there patent search operational yet, and the resolution as displayed is pretty crude). Maybe this is something that was introduced by the manufacturer? I do note that PR claims for the TT cite that the device will not impair speed. If the tunnel does taper, that claim would appear to be dubious. Hey, maybe it’s compressing the water to increase propulsion BTW, I think the Google patent searching is very cool…
You can see it in good size by clicking on the drawing–you can also zoom on it. No taper here. That would be a venturi, right? Giving a low zone at the exhaust? Little drag pocket? WOuld help with tip time, I would think.
You can see it in good size by clicking on the drawing–you can also zoom on it. No taper here. That would be a venturi, right? Giving a low zone at the exhaust? Little drag pocket? WOuld help with tip time, I would think.
Google patents is super-cool.
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Hmmm. Didn’t work in FF 2 for me. I’ll need to go back and see if it’s a browser or operator problem…
Yes, most fins speed the board up, take any of your boards and grind the fins off, the difference will be obvious.
Even vertical flat plane fins offer vertical lift much of the time , and any fin which has horizontal area will provide lift at a better lift/drag ratio than the planing bottom, which is beneficial even if it dosn’t lift the entire hull out.
When I say that the tapered conical section pipe on the turbo tunnel slows the board down, I mean in comparison with a similar fin with a cylindrical pipe.
The turbo tunnel definitely has a tapered tunnel by the way, just checked.
BTW, I think the Google patent searching is very cool…