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A third foil |
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x1testpilot
Posting king Joined: 11 Feb 11 Location: Ealing Online Status: Offline Posts: 175 |
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Topic: A third foil Posted: 13 Apr 12 at 2:22pm |
What is the ideal depth for this type of foil? My guess is that rudder mounted ones are about 1/2 way down for largely practical reasons? This one could be placed exactly right and varied?
As I understood it the foil can be thought of as increasing the effective waterline length of the boat, so presumably less steering is required. I'd also guess that over-steering with foils would be increase drag and reduce the desired effect. I doubt the vertical would measyrably affect steering. si |
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G.R.F.
Really should get out more Joined: 10 Aug 08 Location: United Kingdom Online Status: Offline Posts: 4028 |
Post Options Quote Reply Posted: 13 Apr 12 at 4:08pm |
You trying to stop that tippy X1 thing from falling over by any chance Mr Pilot?
Edited by G.R.F. - 13 Apr 12 at 4:08pm |
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x1testpilot
Posting king Joined: 11 Feb 11 Location: Ealing Online Status: Offline Posts: 175 |
Post Options Quote Reply Posted: 13 Apr 12 at 6:28pm |
Amazingly stable the X1, I can't remember the last time we capsized! X0 too.
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Medway Maniac
Really should get out more Joined: 13 May 05 Location: United Kingdom Online Status: Offline Posts: 2788 |
Post Options Quote Reply Posted: 13 Apr 12 at 9:49pm |
No, it was the workhorse 908, Langheck version, a much nicer, more subtle beast! Edited by Medway Maniac - 13 Apr 12 at 9:51pm |
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Medway Maniac
Really should get out more Joined: 13 May 05 Location: United Kingdom Online Status: Offline Posts: 2788 |
Post Options Quote Reply Posted: 13 Apr 12 at 10:02pm |
As I understand it, the higher you can place the T foil without ventilation, the more upward component you get in the incident flow as it leaves the transom, decreasing drag (by swinging the force generated by the foil more forward) and increasing energy recovery. Another case for mounting the T foil further aft on the rudder... I should have thought the vertical strut would have quite a noticeable effect on damping the steering - ask a board sailor or canoeist |
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craiggo
Really should get out more Joined: 01 Apr 04 Location: United Kingdom Online Status: Offline Posts: 1810 |
Post Options Quote Reply Posted: 13 Apr 12 at 11:35pm |
Medway maniac beat me to it.
You are pretty much correct in your statements regarding the vertical positioning, although too close to the transom and you hit slower boundary layer flow, or seperated flow as it leaves the transom, so there is a sweetspot. The ventilation issues are likely to only be a big issue if you allow the boat to heel and the tip of the horizontal foil breaks clear of the surface, otherwise its actually preferable to have it mounted on foil under the boat rather than the rudder. The hulls then acts as an end plate thus making it harder for air to be drawn in. On the rudder this is harder to acheive, hence small fences on the the rudder leading edge. As for the steering damping, its probably only a significant issue at high speeds when the rudder is probably too large and therefore twitchy anyway so the damping probably smoothes out the inputs a bit! Its certainly an interesting concept and it would be good to here the views of the guys using it. Anyone spoken to them? |
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Cameron Winton
Groupie Joined: 08 Nov 11 Location: Prestwick Online Status: Offline Posts: 41 |
Post Options Quote Reply Posted: 15 Apr 12 at 12:24am |
Ahhh... Didnt see the whole car I stand corrected.
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Medway Maniac
Really should get out more Joined: 13 May 05 Location: United Kingdom Online Status: Offline Posts: 2788 |
Post Options Quote Reply Posted: 15 Apr 12 at 10:35am |
They're pretty similar in Langheck bodystyle. Looking again, I'm struck by the fact that people in 2012 think all-black wheels are new and trendy... Perhaps more on-thread, I've just read that the Langheck was very much a low-drag rather than a high downforce design - so much more into energy recovery like a high mounted T-foil. The alternative bodywork 908/3 was much more concerned with downforce and not with drag, and equates more our foils when they're set only to lift. Note the huge rear wing: |
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Rupert
Really should get out more Joined: 11 Aug 04 Location: Whitefriars sc Online Status: Offline Posts: 8956 |
Post Options Quote Reply Posted: 16 Apr 12 at 8:44am |
All black wheels are trendy? I don't ever wash the car, and my wheels are always pretty much black - that must mean I'm on trend?!
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Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686
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Lukepiewalker
Really should get out more Joined: 24 May 06 Location: United Kingdom Online Status: Offline Posts: 1340 |
Post Options Quote Reply Posted: 16 Apr 12 at 8:51am |
The Langhecks were essentially Le Mans specific where the gains made down the Mulsanne straight were massive, basically the design team were focussed on low drag above all else. This had many consequences, from poor handling to increased brake wear. The Kurzheck was designed for shorter courses, and was also somewhat 'interesting' on the handling front until the boys at JWA attacked the rear deck with some plywood and found the downforce.
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