Builder's Open - Any Thoughts?

Trevor, I strongly urge you to consider a movable ballast ,very narrow fixed keel mono BUT if you absolutely, unequivocally must do a foiler consider one like this:
mfoilerf3_14a.jpg
Address:http://www.microsail.com/images/mfoilerf3_14a.jpg Changed:3:04 PM on Friday, September 29, 2006
Do NOT do a surface piercing foiler though it might be a tad faster in the lighetest of (foiling)wind but this thing generates it's own RM and will smoke anything in over 8 knots of breeze.Except maybe a well sailed monofoiler which I don't even have working perfectly yet and that requires months to learn to sail well-the F3 sails itself! And it lends itself quite easily to retractable foils for 0-5mph and in anything over 5 and it's foiling. Use the Wing Tip Rig -and don't mess with more exotic rigs. Keep the SA/weight at around 200 sq. in. per pound up to 8-10 knots and then have the rig reefable or replaceable.Keep the foil loading(dry) at around .188lb.'s per square inch. Dry foil loading on this type of foiler is the weight of the boat multiplied by .8
divided by the main foil area- one side of both foils only. I use the term "dry" beacause the boat never actually sails at this loading since it uses the foils to develop RM. But it makes a convenient way to size the foils. Keep the SA ( sq.in) divided by the mainfoil area around 5.88 or more. This kind of foiler works better the wider you make it because beam unloads te foils hence earlier takeoff; width DOES NOT slow down tacking. The F3 is 56"LOA and 72" wide. Make the distance between the main foil and rudder foil as large as possible but keep the loading on the main foil at 80% of the total weight. Set the two symetrical main foils at + 2.5° and the rudder at 0° referenced to the nominal staic waterline. I say nominal because I found that the boat took off a little quicker if the whole thing was tilted back a bit from the designed static waterline but only in foiling conditions; in light air such a tilt exacerbated the wetted surface problem with increased drag. There you have it-everything but the altitude control system (wand) which ,if you go ahead, I can help you with.
But I say unto you: do the movable ballast skinny mono......

[frosh]

Doug, I know I promised not to engage with you, but you engaged with me first, after I decided that the presence of one SPAMMER on the forum would not turn me into an idiot, causing me to take offence, and leave forever.
In your latest posting, did the technical information come from a photograph of Rohan Veal foiling on Ronstan (his Moth Foiler). Please forward to me the page number and issue, and name of magazine, so I can do an accurate dimensional check with my Architectural Standard scale ruler.
I understand that you have some serious financial deficencies at the moment, and although I do sympathize with you, I have good reason to believe that scale rulers that are purchased at Wal-Mart come from some backwater factory in China, and are often impressed with graduation lines that are done by a machine costing around 450 yuan (Chinese currency unit) This converts to around US$57 . In my humble opinion no serious NA would design a boat with a scale ruler manufacured by a machine worth only $57.
Therefore neither should you!

[tmark]

Originally Posted by frosh

In your latest posting, did the technical information come from a photograph of Rohan Veal foiling on Ronstan (his Moth Foiler). Please forward to me the page number and issue, and name of magazine, so I can do an accurate dimensional check with my Architectural Standard scale ruler.
I understand that you have some serious financial deficencies at the moment, and although I do sympathize with you, I have good reason to believe that scale rulers that are purchased at Wal-Mart come from some backwater factory in China, and are often impressed with graduation lines that are done by a machine costing around 450 yuan (Chinese currency unit) This converts to around US$57 . In my humble opinion no serious NA would design a boat with a scale ruler manufacured by a machine worth only $57.
Therefore neither should you!

Wrong thread, my friend ... and just a friendly suggestion ... if you want to piss higher than Mr Lord why don't you do it on the race-course ... design build and fly your boat to florida and have a go man to man ... hot air (from whatever its source) dissipates pretty quick at the starting line ...

Trevor

I'd be willing to discuss the details of my previous post with almost anyone to clarify any details that are not understood.

[tmark]

re last post ... Thanks Doug ... whether I take your advice or not, I still appreciate the fact you're willing to take the time to post it ... and I am storing it away.

Given that both sharpie and I are both talking about canting rigs and I've justified it (sort of) I'm curious if anyone would like to critique the idea?

Why not?
Complexity?
Engineering?
Too little gain for too big an effort?
Why do the asymmetrics use them?

Help me out here ...

Regards, T

Builder's Open Update
To bring everyone up to speed here's what's happening so far ... 5 boats are in development, 4 are multi's, 2 builders are proposing canting rigs, at least 2 are proposing foilers, and the 5th has started experimenting with carbon layup ... on top of that 1 builder is talking about a scow with foils that looks kinda like a porpoise, and another is researching Bristol Cutters (not kidding) ...

[Dan S]

Tmark,

you might find this usefull.(canting mast marblehead)

http://www.carbonicboats.com/load.ph...File=Steps.jpg

[tmark]

To those who know ...

Awhile back it was mentioned that a t-foil was the better choice for a model ... what is the relative drawback of a piercing foil? It seems somehow the simpler of the two options. Is there an existing resource that anyone can point to ... ?

Regards and thanks in advance, Trevor Paetkau

Trevor, www.foils.org is good resource for the comparison of these two types of foil on full size boats.
The surface piercing foil is simple because speed controls altitude and it always sails at it's optimum area. The downside on full size boats is sometimes a greater susceptability to foil ventilation which results in a loss of lift. This can be largely prevented by "fences" that stop the ventilation before it can get started.( google l'hydroptere) I discovered ,accidently, that on models ventilation is far less of a problem than on full size boats.
One drawback of a "normal" surface piercing arrangement is that it does not use the foils to develop it's own righting moment. One Australian surface piercing boat- "Spitfire"- used ballast because the designer said "you only have to lift it once" whereas with altitude controlled fully submerged foils the faster the wind blows the greater the load on the foils because the foils keep the boat upright.
On a model ,in my opinion, power to carry sail is most important so in comparing the two systems for use on an RC multihull I'd choose the fully submerged altitude controlled foil system as used on my F3 ( www.microsail.com ). This system is very, very resistant to pitchpole or capsize, and takes off in very light air-5mph-with very high top end speed.
One newer technology being experimented with is a two foil fully submerged system with altitude control-like a Moth-either multihull version or monohull version both of which must use movable ballast. There are serious control problems but it has potential. I wouldn't recommend it now.
A surface piercing system on a model won't have the power to carry sail of the equivalent weight fully submerged system but could be faster in a certain range of wind strength. The altitude controlled fully submerged foiler will likely take off earlier and have greater usable wind range as well as higher top end speed. Both types have serious drawbacks against equivalent weight "normal" RC multihulls in wind under foiling conditions or in waves where the foiler bottoms out. If racing against other RC multihulls a retractable set of main foils would be a good design consideration.
Good Luck! What are you thinkng about?

[Richard Hillsid]

How about a 75 cm long boat with a child sailing it, no price for the rc gear or onboard computer and the added weight would make this interesting, kite hydroplane? or submerged only head above WL.

What the hek its Saturday evening

[tmark]

Thanks Doug ... you asked what I was thinking ...

The attached sketches (not to scale) show the platform ... it's entirely experimental at the moment but should illustrate what I'm thinking.

Should she prove doable, I will test three rigs on her ... a) a wing tip; b) a swivelling, canting rig (rig moves to leeward at the end of a pivoting rod, and at the same forcing a windward cant); and c) a wingmast flying a code 0.

Regards, Trevor

Trevor, cool looking boat but ,as drawn , probably impractical for an RC model. A model foiler needs to have-at a minimum- enough buoyancy to leeward to absorb a 10 knot gust without capsizing the boat. That's a rule of thumb I developed in experiments before the F3 and it works throughout the wind range-the wider the boat the less buoyancy required and the smaler the "ama" or buoyancy pod can be.
Also, in addition to what I said in the previous post: no matter what foil system you use the further apart the forward foils the better because it unloads the foils. For reference: the F3 is 56" LOA and the distance between the center of lift of the main foils is 60". The extra beam DOES NOT reduce tacking ability!
Also be sure that the forward foils take about 80% of the load and keep the distance between the main foils and rudder foil as great as possible.
Good Luck!
----------------------
Notes:
-for earliest takeoff aim for as close to 200 or more square inches SA/lb. of boat weight as possible for the number 1 rig; make it reefable
-aim for 50 square inches SA/per sq.in of mainfoil area or more.
-F3 7.5 lb.; 34 sq.in mainfoil area(2 foils); remember that the F3 uses independent wand type altitude control systems on each main foil so that the loading of the foil is greater at takeoff than what is reflected by the above numbers and just goes up as the boat goes faster.

[tmark]

need for leeward bouancy countered by windward canted rig ... lift cancels heel ... may be possible to build bouancy requirements into the foils (this is exactly the kind of input I need btw ... thx)

as mentioned drawings are not at all to scale ... she can be built as wide as is require to make her work ...

to summarize so far ... gust protection required, widen stance, 80% of load up front

[Jon Howes]

Tmark,

I have been watching some of these discussions for a while but finally feel compelled to comment:

You wrote:

"Sail Rocket / MonoFoil / Jelly Fish Foiler

More experimental. Theoretically faster. These boats, like the Macquairie are asymmetric, one way speed machines. Each uses different methods to achieve the same ends. Essentially they attempt to balance vertical lift against opposing keel/foil force. And, if done right, a gust or shift will not topple these boats."

Monofoil is NOT A ONE TACK BOAT!!!!

That large cross beam that has the foil at one end and the wing at the other swings through 360 degrees, the rig is self feathering to the apparent wind and the boat is absolutely equal on both tacks. Everyone seems to miss this rather key feature and it is getting a little frustrating!

Regards,

Jon Howes,

Designer, Monofoil.

[tmark]

Originally Posted by Jon Howes

Monofoil is NOT A ONE TACK BOAT!!!!

. Everyone seems to miss this rather key feature and it is getting a little frustrating!

Jon Howes,

Designer, Monofoil.

Thanks for the note ... the boat is a remarkable achievement, and the fact that she works on both tacks makes it even more so ... kudos and respect all'round ... !!!

The only thing I might add is that you may wish make her tacking ability more explicit on your site ... I missed it, and it sounds like others are doing the same ...

Regards and best wishes ... Trevor Paetkau