| Kickup T foil rudder #106508 05/09/07 06:43 AM 05/09/07 06:43 AM |
Joined: Aug 2002 Posts: 545 Brighton, UK grob OP
addict
|
OP
addict
Joined: Aug 2002
Posts: 545 Brighton, UK | What do people think of this kickup T foil rudder setup? The system is very simple. The T-foil is attached to the bottom of the main rudder blade, and is allowed to pivot freely. Referring to the sectioned plot below, the T-foil is also attached to the rudder box via a line that runs through the rudder blade. When the rudder blade is in the vertical deployed position the line pulls the T-foil tight against the bottom of the rudder blade holding it in a horizontal sailing position. When the rudder blade is released to swing to the horizontal position the T-foil is also automatically released. Although this is currently shown on a Dotan stock (as this is what I use) it can be retrofitted to any existing kickup rudder system. Gareth | | | Re: Kickup T foil rudder
[Re: grob]
#106509 05/09/07 07:34 AM 05/09/07 07:34 AM |
Joined: Jun 2001 Posts: 9,582 North-West Europe Wouter
Carpal Tunnel
|
Carpal Tunnel
Joined: Jun 2001
Posts: 9,582 North-West Europe | Not enough distance difference as a result of the pivoting to pull the T-foil in tight.
The radius from the fullcrum to the point where the line enteres the rudder boards is too short.
Maybe have a pully on the stern and a clear on the rearbeam so the skipper can activate and deactivate the T-foil ? (an idea I had for the F12) But still have the problem of the line stretching resulting is a flapping T-foil possibly damaging the rudder board itself.
Wouter
Last edited by Wouter; 05/09/07 07:37 AM.
Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands
| | | Re: Kickup T foil rudder
[Re: grob]
#106510 05/09/07 07:46 AM 05/09/07 07:46 AM |
Joined: Jun 2001 Posts: 12,310 South Carolina Jake
Carpal Tunnel
|
Carpal Tunnel
Joined: Jun 2001
Posts: 12,310 South Carolina | Interesting thought. I would first be concerned about flutter of the foil if it kicks up while the boat is moving at any decent speed...that is, unless you built in some imbalance stability into the foil - but that would result in undesirable drag during normal attitude. I know first hand that control surface flutter can be violent and result in the death of a model airplane!
The geometry between the pivots and the line seems to be a bit off - but that might actually take care of the potential for flutter if it can be arranged put the foil at a slight bit of a "down plane" attitude when it is released.
Jake Kohl | | | Re: Kickup T foil rudder
[Re: Jake]
#106511 05/09/07 08:04 AM 05/09/07 08:04 AM |
Joined: Jan 2005 Posts: 6,049 Sebring, Florida. Timbo
Carpal Tunnel
|
Carpal Tunnel
Joined: Jan 2005
Posts: 6,049 Sebring, Florida. | Why not just improve the lifting mechanisim on the present casette type T foil rudders? Personaly I like the idea of only having half the rudder, or less, down when coming in to or departing the beach. You will still have a lighter helm than with a kicked up rudder, which can be hard to steer in big wind and waves. And it would seem the casette type system would be lighter, less moving parts to break, etc.
Could someone who uses the present T foil rudders please post a close up picture of the headstock and the rudder in both the up and down possition, and tell us how it works? Thanks.
Last edited by Timbo; 05/09/07 08:07 AM.
Blade F16 #777
| | | Re: Kickup T foil rudder
[Re: grob]
#106515 05/09/07 08:48 AM 05/09/07 08:48 AM |
Joined: Nov 2003 Posts: 99 Chicago, IL Krisu13
journeyman
|
journeyman
Joined: Nov 2003
Posts: 99 Chicago, IL | If you are not going to do any backward sailing - just eliminate the line going through rudder blade.
I20
| | | Re: Kickup T foil rudder
[Re: Special_Treat_P182]
#106516 05/09/07 08:55 AM 05/09/07 08:55 AM |
Joined: Jan 2005 Posts: 6,049 Sebring, Florida. Timbo
Carpal Tunnel
|
Carpal Tunnel
Joined: Jan 2005
Posts: 6,049 Sebring, Florida. | The guys who have them like them, I think the Stealth (F16 type) has them, they say they really smooth out the ride and keep you from nose diving in a windy gibe. The Jurry is still out on wether they are "faster" or not, but swimming is slow.
Blade F16 #777
| | | Re: Kickup T foil rudder
[Re: Timbo]
#106517 05/09/07 08:55 AM 05/09/07 08:55 AM |
Joined: Jun 2001 Posts: 12,310 South Carolina Jake
Carpal Tunnel
|
Carpal Tunnel
Joined: Jun 2001
Posts: 12,310 South Carolina | Why not just improve the lifting mechanisim on the present casette type T foil rudders? Personaly I like the idea of only having half the rudder, or less, down when coming in to or departing the beach. You will still have a lighter helm than with a kicked up rudder, which can be hard to steer in big wind and waves. And it would seem the casette type system would be lighter, less moving parts to break, etc.
Could someone who uses the present T foil rudders please post a close up picture of the headstock and the rudder in both the up and down possition, and tell us how it works? Thanks. I hadn't thought of that - boy that would be really nice.
Jake Kohl | | | Re: Kickup T foil rudder
[Re: Jalani]
#106519 05/09/07 09:15 AM 05/09/07 09:15 AM |
Joined: Jan 2005 Posts: 6,049 Sebring, Florida. Timbo
Carpal Tunnel
|
Carpal Tunnel
Joined: Jan 2005
Posts: 6,049 Sebring, Florida. | Thanks for the picture John, now, tell us about the ride with the T foils. (I know this was covered a year or so ago, any updates?)
Blade F16 #777
| | | Re: Kickup T foil rudder
[Re: Timbo]
#106520 05/09/07 09:20 AM 05/09/07 09:20 AM |
Joined: Feb 2005 Posts: 1,382 Essex, UK Jalani
veteran
|
veteran
Joined: Feb 2005
Posts: 1,382 Essex, UK | The ride has been discussed at length, as you say, having sailed with them, I couldn't now imagine sailing without them! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />
Only update is the new Stealth (2006/7) T-foils are a fantastic improvement on the older ones. Small, lighter, stronger and much better engineered. Less drag IMO, but just as effective as the older, larger foils. John_P has done a really good job!
John Alani ___________ Stealth F16s GBR527 and GBR538 | | | Re: Kickup T foil rudder
[Re: Jalani]
#106521 05/09/07 09:35 AM 05/09/07 09:35 AM |
Joined: Jan 2005 Posts: 6,049 Sebring, Florida. Timbo
Carpal Tunnel
|
Carpal Tunnel
Joined: Jan 2005
Posts: 6,049 Sebring, Florida. | If I wanted to buy a pair to put on a US Blade, what would that cost, for the new ones? Rudders, heads, tillers and mounts?
Blade F16 #777
| | | Re: Kickup T foil rudder
[Re: Timbo]
#106522 05/09/07 11:45 AM 05/09/07 11:45 AM |
Joined: Feb 2005 Posts: 1,382 Essex, UK Jalani
veteran
|
veteran
Joined: Feb 2005
Posts: 1,382 Essex, UK | Your best bet Tim would be to cantact John Pierce - either PM him (john p) or through the website: http://www.stealthmarine.co.uk
John Alani ___________ Stealth F16s GBR527 and GBR538 | | | Re: Kickup T foil rudder
[Re: Laruffa]
#106526 05/10/07 07:28 AM 05/10/07 07:28 AM |
Joined: Jun 2001 Posts: 12,310 South Carolina Jake
Carpal Tunnel
|
Carpal Tunnel
Joined: Jun 2001
Posts: 12,310 South Carolina | Hi everyone, Would like to ask you a question, after sailing 49ers I always ask the question why not!! rudders in a box system?? they have some good points 1)when you need to sail into or out of a beach with any seaway they would work well if you could just left them up to miss the bottom and still steer! 2)packing the boat for transport all you need to do is take them out and pack them into a bag like the centre boards! 3) they would never kick up under load or sailing in waters with things like jellyfish! 4)if anything fouled them like seawead you could still steer while lifting them free! 5)in conditions like high winds with flat waters you could lift them to reduce drag?? [color:"red"] [/color] disadvantages? 1)hitting a object or the bottom in shallow waters?? BUT would it be cover by the centre boards???? whats your thoughts!!!! Love allways MarkXX <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" /> I too like the idea of a cassette style rudder. Big jellies are not usually a risk to the structure of the boat but things like stumps or perhaps a rock outcropping might be. However, you could still have some sort of breakaway "fuse" at the gudgeon in the event you really did hit something hard.
Jake Kohl | | | Re: Kickup T foil rudder
[Re: grob]
#106527 05/10/07 09:08 AM 05/10/07 09:08 AM |
Joined: Jun 2001 Posts: 1,449 phill
veteran
|
veteran
Joined: Jun 2001
Posts: 1,449 | Gareth, Intersting concept. Obviously it would need some work to refine. Got me thinking could even replace the line with thin flat rod down the centre of the rudder. When building the rudder a slot could be made down the centre to accomodate the rod. Now if you can control the rod from the top you would also have the ability to adjust the angle of the T foil while sailing.
Regards, Phill
I know that the voices in my head aint real, but they have some pretty good ideas. There is no such thing as a quick fix and I've never had free lunch!
| | | Re: Kickup T foil rudder
[Re: grob]
#106528 05/10/07 10:57 AM 05/10/07 10:57 AM |
Joined: Nov 2003 Posts: 130 CA Glenn_Brown
member
|
member
Joined: Nov 2003
Posts: 130 CA | What do people think of this kickup T foil rudder setup? Since drag is proportional to lift, the rudders would be prone to kicking up at speed... more so than conventional rudders. Is the foil slapping the water's surface going to interfere with the Dotan stock operation? Wear on the line/rudder entering the channel at an angle is an obvious concern. A steel rod bearing would help. Wouter rightly pointed out geometry problems with the line/channel placement. These could be addressed simply by making the line ride a cam around the top axel, with the cam radius matching the bottom axel-line separation. The "channel" through the rudder need not be parallel to rudder trailing edge. You need some adjustment somewhere to get the line length just right. You probably need a little stretch in line line to so you can get the rudders down with tension on the line. The hinge can only add drag, but kick-up eliminates the problem of cassettes scratching the foil, so you could possibly use a laminar flow foil section for less drag and make up for it. | | | Re: Kickup T foil rudder
[Re: phill]
#106529 05/10/07 11:19 AM 05/10/07 11:19 AM |
Joined: Jan 2005 Posts: 6,049 Sebring, Florida. Timbo
Carpal Tunnel
|
Carpal Tunnel
Joined: Jan 2005
Posts: 6,049 Sebring, Florida. | Gareth, Intersting concept. Obviously it would need some work to refine. Got me thinking could even replace the line with thin flat rod down the centre of the rudder. When building the rudder a slot could be made down the centre to accomodate the rod. Now if you can control the rod from the top you would also have the ability to adjust the angle of the T foil while sailing.
Regards, Phill I think the foiling Moths have a setup like that, where they can adjust the anlge of the rudder foil by tweeking something on the tiller.
Blade F16 #777
| | | Re: Kickup T foil rudder
[Re: Timbo]
#106530 05/10/07 02:22 PM 05/10/07 02:22 PM |
Joined: Jun 2001 Posts: 12,310 South Carolina Jake
Carpal Tunnel
|
Carpal Tunnel
Joined: Jun 2001
Posts: 12,310 South Carolina | Gareth, Intersting concept. Obviously it would need some work to refine. Got me thinking could even replace the line with thin flat rod down the centre of the rudder. When building the rudder a slot could be made down the centre to accomodate the rod. Now if you can control the rod from the top you would also have the ability to adjust the angle of the T foil while sailing.
Regards, Phill I think the foiling Moths have a setup like that, where they can adjust the anlge of the rudder foil by tweeking something on the tiller. They used to twist the tiller to adjust the attitude of the rear foil - however, I believe they've all gone away from that and have found that a fixed rear foil works just fine and is less hassle.
Jake Kohl | | | Re: Kickup T foil rudder
[Re: Jake]
#106532 05/10/07 10:15 PM 05/10/07 10:15 PM |
Joined: Apr 2002 Posts: 805 Gainesville, FL 32607 USA dacarls
old hand
|
old hand
Joined: Apr 2002
Posts: 805 Gainesville, FL 32607 USA | The plain old conventional Hobie 14 castings used on the hydrofoiler rudders in my thumbnail pic worked pretty well and never broke. Neither did the rudders. They are on my boat, the only hydrofoiling Hobie 16 in the world. 8^)
Dacarls: A-class USA 196, USA 21, H18, H16 "Nothing that's any good works by itself. You got to make the damn thing work"- Thomas Edison
| | | Re: Kickup T foil rudder
[Re: Darryl_Barrett]
#106534 05/10/07 11:03 PM 05/10/07 11:03 PM |
Joined: Oct 2005 Posts: 951 Brisbane, Queensland, Australi... ncik
old hand
|
old hand
Joined: Oct 2005
Posts: 951 Brisbane, Queensland, Australi... | Darryl, do they also make it a bit more difficult to lift a hull in marginal conditions because of the down force they generate on the windward hull?
There are scaling problems with the following anecdote but...I have built and raced model trimarans (mini40) for awhile and have found that T-foils haven't been faster in most conditions. Upwind, the extra drag from them and extra drag from not being able fly the hulls was slow. They made it harder to sail downwind, which was when they were supposed to work, because the boat wouldn't accelerate as fast in a gust, which would load up the rig making it want to nose-dive.
As I said, there are scaling problems with the anecdote but the main problem I see with T-foils on multihulls in general is making sure you can still lift a hull, probably only a problem in marginal conditions. | | | Re: Kickup T foil rudder
[Re: ncik]
#106535 05/10/07 11:55 PM 05/10/07 11:55 PM |
Joined: Jun 2001 Posts: 1,449 phill
veteran
|
veteran
Joined: Jun 2001
Posts: 1,449 | Gero, Interesting that you should mention lifting hulls. Two things to note: I believe John P has mentioned on the forum that the T foils dampened the affect of gusts lifting hulls upwind. So in gusty conditions they made the boat more stable giving greater acceleration from the gusts as well as the additional affects of stabilizing the pitching motion allowing the sails to generate more power.
Someone using Darryl's T foils was telling me at a regatta that he was lifting the windward hull downwind and then moving a little further aft and resting the windward hull back down on the windward foil with the hull remaining clear of the water. This allowed a slight bias in the downward loading of the hull making the boat more stable while still flying the windward hull. So he could keep the hull up in marginal conditions reducing the wetted surface drag as well as being able to drive the boat better with the added stability.
I think we still need to do a bit more experimenting, even so I expect T foils will find a permanent place in all progressive catamaran classes in time.
Now the next step could be independent adjustment of foils to help lift the windward hull in light conditions. Interesting thought that would be fun to play with but unlikely it could be made simple enough to not cost more time through poor adjustment than gained.
But you never know until you give it a go.
Regards, Phill
I know that the voices in my head aint real, but they have some pretty good ideas. There is no such thing as a quick fix and I've never had free lunch!
| | | Re: Kickup T foil rudder
[Re: phill]
#106538 05/11/07 03:06 PM 05/11/07 03:06 PM |
Joined: Aug 2001 Posts: 1,307 Asuncion, Paraguay Luiz
veteran
|
veteran
Joined: Aug 2001
Posts: 1,307 Asuncion, Paraguay | I think we still need to do a bit more experimenting, even so I expect T foils will find a permanent place in all progressive catamaran classes in time. Agreed. And I guess cats would use L foils instead of T foils. They are more efficient. But, as you said, we will only know if we try. Cheers,
Luiz
| | | Re: Kickup T foil rudder
[Re: ncik]
#106539 05/11/07 06:11 PM 05/11/07 06:11 PM |
Joined: Jul 2001 Posts: 183 john p
member
|
member
Joined: Jul 2001
Posts: 183 | Gero
We felt in testing that in gusty conditions the T-foil equipped boat was less 'flighty', in other words it was less prone to violent hull lifting in gusts, this is dificult to measure and was more a feeling, we put it down to the following effect.
When hit by a gust the non t-foil boat would accelorate at the same time as the hull lifted, this extra drive produces a small dip as the bows go down under acceleration.
On the T-foil equipped boat the bows don't dip because the T-foils hold the boat steady, but of course to do this they apply downforce , also as the rudder lifts it is no longer travelling horizontally but is sloping up, these 2 effects produce downforce on the rudder which on the windward one equates to an extra force resisting hull lift.
The net result of this is that it is just as easy to fly a hull and the same wind strength is required to do it either way, it is just that it dampens the effect of gusts, and lulls(because the reverse happens then).
John Pierce
[email]stealthmarine@btinternet.com /email] | | | Re: Kickup T foil rudder
[Re: Rolf_Nilsen]
#106541 05/12/07 12:52 AM 05/12/07 12:52 AM |
Joined: Jun 2004 Posts: 1,479 Thailand Buccaneer
veteran
|
veteran
Joined: Jun 2004
Posts: 1,479 Thailand | I like them, and think kick-up rudders are a leftover from the rotating centerboard days. Today the daggerboard (unless you have skegs) will hit the ground before the rudders, so you will ruin your day anyway. The rudders normally come up after and go down before the boards so they are of course more susceptible but with the kick up function that is not an issue. For example I pull the boards up and surf in until I’m in about knee deep water. If I misjudge the tide then once in a blue moon I hit a rock and a rudder kicks up. No big deal. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> Maybe better to build a cassette with a simple kick-up function (not unlike top cat) as insurance against ripping the stocks off on the reef? <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" />
"House prices have risen by nearly 25 percent over the past two years. Although speculative activity has increased in some areas, at a national level these price increases largely reflect strong economic fundamentals." – Ben Bernanke – 2005
| | | Re: Kickup T foil rudder
[Re: Buccaneer]
#106542 05/12/07 04:56 AM 05/12/07 04:56 AM |
Joined: Jun 2001 Posts: 9,582 North-West Europe Wouter
Carpal Tunnel
|
Carpal Tunnel
Joined: Jun 2001
Posts: 9,582 North-West Europe | Bob,
Darryl tested his T-foil rudders as plain kick-up rudders. Meaning you use the exact same stock as you are using now but not with rudderboards with the little foils attached to the their ends.
He reported that there is no issue hitting the bottom, the T-foil rudders will kick up just the same as the normal rudders do. The T-foils won't break as they need to be strong enough to withstand the normal operating forces anyway. and maybe apart from some extra drag that slows the boat down nothing else happens. This may all not be a bad thing when landing.
The only issue left is leaving the beach with the rudders kicked up. I don't fancy working my way through the surf like that, but experimentation might proof otherwise. Afterall the T-foil rudders aren't that large in area. Also if you don't have to launch through the surf but can walk the boat in to sufficiently deep water and put the rudders down then there is no issue left at all. Then you can just have T-foils added to your current rudderboard design and use all the old kick-up hardware.
Again Darryl sailed the F14's like that for a long time now and everything is still fine. I think they even didn't modify the rudder pintle setup from what the quick snap on system they had on there. Apparently the forces generated on these part are relatively small and it is the large leverage they have there in the back of the boat that does the major part of the work.
I have no experimentation money left otherwise I would order a test rudderboard like that and just fit is to my current ruddersystem and find out what really is a problem and what isn't. The Taipan is one of the hull designs that could really benefit from the T-foils.
I was very impressed by them when I sailed the Stealth a few times.
Ohh, and there is another principle that is of interest here. John Alani expressed a while back how he approaches a landing site with the cassette rudderstocks.
When he approaches shallow water he pulls out the retaining pin, now the rudderboard can slide up and down through the cassette depending on the vertical forces produced by the T-foils. In effect he can lower the rudderboards by moving his weight forward and putting the hull in a small bow down angle. And he can raise his rudderboards by moving his weight back and putting the hull in a bow up angle. He uses this phenomenon to lower and raise his boards when leaving the beach or landing. Just before the rudders are about to hit bottom he apparently moves his weight back and thus have them lift themselfs clear. This way he covers the last stretch of water and then steps off.
This phenomenon may even be an advantage of the cassette tape rudderstocks, because you can always get as much rudderboard in the water as you need/can without having the large tiller loads or having to use your hands or go to the back of the boat ! Your hands are now free to hold the sheet and tiller. Once through the surf you can head up into the wind and fit the retaining pins and go sailing.
I think there is some excellent development to be had with the T-foil rudders and I truly believe that we will see them fitted to beach cats more and more. Especially in the range where hull length are relatively short. Personally I'm planning on using them on the F12 design and I would love to have them on my F16.
Wouter
Last edited by Wouter; 05/12/07 05:07 AM.
Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands
| | | Re: Kickup T foil rudder
[Re: Wouter]
#106543 05/13/07 07:54 PM 05/13/07 07:54 PM |
Joined: Feb 2004 Posts: 1,012 South Australia Darryl_Barrett
old hand
|
old hand
Joined: Feb 2004
Posts: 1,012 South Australia | There is the old adage for any design, K.I.S. (keep it simple) and there is a lot to be said for the absolute simplicity of the cassette system. No cams, no pivoting points, virtually no wear points, never any necessity for fore and aft adjustment for tuning, etc, and their sheer simplicity overcomes a lot of potential (and real) problems that are inherent in all other rudder systems. I was initially doubtful about using the cassette system, considering it “old fashioned” but after extensive testing and use now, I actually prefer them to a “kick up” system | | |
|
0 registered members (),
181
guests, and 102
spiders. | Key: Admin,
Global Mod,
Mod | | Forums26 Topics22,405 Posts267,057 Members8,150 | Most Online2,167 Dec 19th, 2022 | | |