Regardless of how much the ama hull submerges CLR doesn’t change; that is a function of the placement of the ama and the 10 to 1 or more higher lift (lateral resistance)provided by the vertical hydrofoil in light air.
The retractable foil system keeps the “high lift” part of the underwater area in exactly the same place in any condition foiling or not.
Doug Lord
–High Technology Sailing/Racing
HI,
<font color=“red”>A PICTURE is worth 10,000 WORDS</font id=“red”>.
Sorry for the misquote!.
John.
Dick
The centre of lateral resistance won’t change if the foils are deployed or raised. What will change is the amount of resistance.
To simplify: if you take a piece of hardwood and push it through the water end on it has a centre of resistance which is at the centre of the end of the board. Now if you turn the piece of wood through 90 degrees and push it again it will still have the centre of resistance in the centre of the board.
The question I would like top ask is why hasn’t the post by Peter been answered yet?
It has the most interesting question and statement in it, but to date no reply.
Thanks StevenA
Didn’t see that post ; don’t know how I missed it.
The VERTICAL foils(FINS) are mounted in a carbon tube that is in turn fitted in another carbon tube with delrin bushings.THE HYDROFOIL IS ATTACHED TO THE BOTTOM OF THE VERTICAL FIN. The Larger carbon tube is fixed to the cross arm in a manner that allows it (and the foil)to be adjusted in angle of incidence.
The “wand” is fitted to the aft end of the same tube the foil(VERTICAL FIN/HYDROFOIL COMBO) is fitted to and rotates up when the foil(VERTICAL FIN/HYDROFOIL COMBO) does.This same tube is connected each side via push rod to the servo.(BY A TWO SIDED GLASS CONTROL HORN)
There are two forces acting on the fin/foil assembly(that concern retractability)-lateral resistance and lift:
1)The lateral resistance being developed by both vertical fins(on each side) neutralize that force in relation to the servo: on stb tack the port foil is being pushed toward the retract position(toward the main hull) but the stb vertical fin is being pushed outboard so there is a net zero of force transmitted to the servo from lateral resistance either during retract or deployment of the foils.
2)The hydrofoils are L shaped with the longest part outboard; the lift on the foils tends to hold them in place. When they are retracted: as the center of lift crosses the pivot point the small remaining lift (less than 20% of max) helps the servo retract them.
In the opposite direction there is virtually no force acting on the servo until the foils AND wand are in position. So either retacting or deploying the force on the servo is extremely small- generally less than a third of that developed by a 3801 servo which is used to move the foils.
The whole assembly moves 90 degrees in less than one second allowing the system to be able to be used to catch and “foil” gusts and to then be retracted.
edt: add text in capitals
edt:sp/(u)
Doug Lord
–High Technology Sailing/Racing
I think people are getting lost in semantics. It would seem highly likely to me that the overall balance and the optimum rig placement of a boat (multihull or monohull) on foils would be different from that of a boat not on foils.
From years of sailing and testing model boats I can say with some high degree of certainty that theory never exactly matches up to the real world.
And to the best of my knowledge no retracting foil r/c multihull has ever been sailed.
Having completed several years of foiler design including many months of two boat testing I can say unequivocaly that the balance of a foiler does not change betwen foiling and not foiling. The only noticeable change besides speed is helm sensitivity; balance is unchanged.
Doug Lord
–High Technology Sailing/Racing
Just to clarify–are you stating that you have built, sailed and tested for “many months” two retracting foil multihulls?
<blockquote id=“quote”><font size=“1” face=“Verdana, Arial, Helvetica” id=“quote”>quote:<hr height=“1” noshade id=“quote”>Originally posted by lorsail
Having completed several years of foiler design including many months of two boat testing <hr height=“1” noshade id=“quote”></blockquote id=“quote”></font id=“quote”>
*** Please see post in the PUB so as not to upset the moderator as I go (slightly) off topic.
I was referring to the F3 specifically in response to the question of whether the balance of a foiler changes from a foiling mode to a non foiling mode.
Since I have already shown that the CLR of the retractable foiler does not move(F&A) during the deploy/retract process the same thing ,of course ,applies to a retractable foiler.
Doug Lord
–High Technology Sailing/Racing
Quote;--------------------------------------------------------------------------------
Just to clarify–are you stating that you have built, sailed and tested for “many months” two retracting foil multihulls?.
The answer to this question is either<font color=“red”>YES or NO</font id=“red”>.
John.
<blockquote id=“quote”><font size=“1” face=“Verdana, Arial, Helvetica” id=“quote”>quote:<hr height=“1” noshade id=“quote”>Originally posted by lorsail
I was referring to the F3 specifically in response to the question of whether the balance of a foiler changes from a foiling mode to a non foiling mode.
<hr height=“1” noshade id=“quote”></blockquote id=“quote”></font id=“quote”>
Ummmm Doug - no one was talking about the F3 at all. The entire post was regarding the retractible foiler.
Do we need to start over again?
b: [/b]If the boat goes from foiling to non-foiling when foils are retracted, wouldn’t the rig need to shift aft since it appears to be a non-foiling boat?
b: [/b]But if the foil area is reduced when you rotate them, and the hull ama area underwater is increased, wouldn’t CLR move aft?
That is pretty much a recap of the topic - INCLUDING your post of “many months of two boat testing …”
… and when questioned, “<u>SUDDENLY</u>” we are talking about the F-3! Can’t you stay with a topic without going back to the F3? We were discussing <u>RETRACTABLE</u> foils - so explain how an F3 testing has anything to do with retractable foils and their ability to NOT change CLR when underwater lateral surface area changes - both in size and in location?
I would also ask the same questions Roy and Jay Dee did … <u>“Are ANY X3 multihulls sailing and being tested against each other?”</u> If they aren’t, then nothing (as yet) has been proven - Still only your theory!
The answer to the question asked by me and then again by StevenA is B.S.
If you read it slowly and fully it’s saying that this boat won’t work, so retractable foils are a theory only, brain explosion.
Without having rods, and arms etc going all over the place, what he is trying to say is impossible.
Explainations for this comment could follow, but they really aren’t worth airing as it just takes up space.
Peter
B.S.? Are you really sure ,Peter?
Doug Lord
–High Technology Sailing/Racing
Yes Doug i think he is really sure.
just answer the stupid question, or stop posting about stuff and then not backing it up.
Doug
If this thing can really work draw a picture and post it. Better still build the thing and show it actually working.
This vertical fin must be a fin not just a tube otherwise there is no lateral resistance.
The push rod that is attached to it is attached where(by your post)I’m guessing the top somewhere. If this is so the force from the servo isn’t going to move anything. If it’s attached to the bottom of the fin then there is the length of rod problem, it will only move so far before the rod will want to either break or come away.
Then there is the problem of the movement available from the servo is far less than what is required to do what you say it will.
Then we look at angles etc etc the problems with this proposal are endless. Or is it going to be a case that I 'm totally wrong?
If this is the case and I am wrong. I ask again post a picture of your plan so that I can see for myself what your imagining.
Peter
Hey people like I said in a previous post, Doug must like to sit and look at his designs and not make thwm available to the general public.
It may be that or it’s they are still in his head and unlike most of the world’s designers he talks about them like they are real.
I am always thinking about what to make next and what new idea might work, but if I’m not going to build it I don’t talk about it.
Thanks StevenA
Doug Lord,
Just to clarify–are you stating that you have built, sailed and tested for “many months” two retracting foil multihulls?.
This question was asked of you,you have failed to reply, are we to conclude from your silence that the answer is <font size=“6”><font color=“red”> NO?</font id=“red”></font id=“size6”>.
John.
I reread what I wrote and I used foils interchangeably for the vertical fin and hydrofoil. Sorry for the confusion; if you re-read it now it will make more sense.
The critical point is that the vertical fin is mounted permanently in the smaller carbon tube. That tube fits into the larger carbon tube with delrin bushings with stops affixed each end to prevent fore and aft movement.
The pushrod is connected to the smaller tube via a short epoxy glass arm permanently added to the small tube after assembly.
Send me a stamped self addressed envelope and I will send you a sketch or send your e-mail and will attempt to have my secretary scan it and send it though the drawing is probably too big to be done that way.
Doug Lord
–High Technology Sailing/Racing
(Mr. Jay Dee) My original response was to Mr. Langbord’s comment where he said that in his experience with many rc sailboats that he would conclude that the balance (and rig position)would be different between a boat on foils as opposed to a boat off foils. I said that in several years of testing and sailing foilers including many months of two boat testing that that was not the case.
The two boat testing was primarily with two F3’s for several months and the F3 and Flyer?.I have sailed two prototype rc foilers in addition to the F3 and in no case does the balance change between being on and off foils.
No two boat testing of the X3
yet. As stated in Foiler Design 1&2 the X3 has not been test sailed as of today but EVERY system used on it has been tested and test sailing will begin in a while. And two boat testing ,just as I’ve done with every boat I’ve built, will begin shortly after that.
Doug Lord
–High Technology Sailing/Racing
Doug,
I for one can not bring myself to believe
you, you have again hidden your answer in a load of ABCDs and numbers, designed to confuse.
Your original post will be subject to one of your sly Edits, no doubt in the near future.
As I said in an earlier post - -and I broke my Word - -this WILL be the last time I will converse with you on ANY subject, I promise you I will NOT lower myself by answering any more of your stupid posts.
Goodbye Doug Lord, I would like to say it has been nice knowing you,BUT, I dont tell lies!.
John Dowd.