Fila #89 b-rigg fun and "Narrow" the F5g

While in Premantura i got the chance sail the new Fila with the b rigg.
I am satisfied with the result. Handling or speed aren't revolutionary but hadling is difinately improoved over evolution. Tacking is easier, There is also less nose down(logicaly, both boats have a wide stern, but fila has the hull shape made out of "circles", meaning there is less volume far from the centerline and low down, far from deck. So the rigg can "sink" the stern abit) Upwind, that is aspecially noticeable when bearing away.
I am still not happy with handling while reaching. The boat is forced to sail where it is pointing. Using even a small amount of rudder means loosing loots of speed. The bow is also too low in the water. Usually waves are not exactly perpendicular to the wind direction. Meaning that the boat can fly(go as fast as it can) one way, making that course really fun.
Reaching the other way sucks. Bow keeps digging. It is too low in the water. With all new components the boat will be circa. 150-200g lighter than it is on the photos but that won't solve the issue. It needs some kind of foiler under the bow, since no real lift is obtained from the sails.

Reaching the fun direction, note: bow up :D

When a wave ends(and there is no wave in front to plow into) there is enough downforce from the foil to sink the boat a couple cm.

The boat stays flat. It just sits deeper. Yes it is bad for the speed, but still better than a nosedive.

Downwind is just so much fun whe ne wind is above 15 knots.

Upwind:

The jib is 3 seasons old now. But the shape is still good

Handling upwind is excellet, or maybe just matched to my preferences.

I was too lazy to take blog worthy shots of the boat sailing with the a rigg. So it is going to happen in the next days, here in home waters.
I am just waiting for a day that won't be 35C hot, because that heat kills the morningbreeze, which usually develops into a steady 10knots if the temperature stays below 30.

Meanwhile the bulb for fila 89 is almost finished, next is the carbon keel fin.

Also i am working on a narrow f5g and rg65 with shadows borrowd from the f5g.

The f5g will weight somewhere between 1200 and 1270g, max. beam will be 6cm. The narrowes f5g ever.(exept if this gets finished sonner: http://forum.modelarji.com/viewtopic.php?f=13&t=90474)
It's atribute will be weight and low WSA, it has less than half of the WSA than Evolution!
The construction will be really simple. It will be hot wire cut from a block of stirodur/depron foam, the edges will be sanded to a 10mm radius and it will be glassed with epoxy. Foam will be removed with acetone. Not a revolutionary tehnique but efiicent with time.
The goal of the boat is to set a new standard for sailing in light winds(koseze) and to see how a really slender hull behaves at speed. With help of my foiled rudders i am plannig to sail above hullspeed, for now probalby only downwind.

Evolution clips

One day a small storm came in at Premantura, the wind was Yugo, know as a warm, humid wind creating good waves out in the open.
When the clips were shot the average wind was about 18knots, you can see the wave size for yourself.
The handling downwind was excellent, no drama. The only reason for not flying the a rigg is the inability or the poor ability(even with b rigg) to tack, when sailing upwind.
This is due to the low mass of the boat and the waves.
I don't know if anyone ever sailed an f5g boat in such winds. As the races are usually held on clam ponds.
Whatever, if such conditions arrive at a race i will be out sailing, having fun with my model yacht.

The sea and the salt featuring evolution

At the moment i am in Premantura, Croatia near Pula.
Evolution passed it's first hours sailing in saltwater with no problems.
Today the wind was up at 11am gusting just above 15 knots with about 20cm waves.
Perfect conditions for f5g b-rigg.
I was sailing evolution, with a b-rig borrowed from Fila, and a new slightly bigger rudder with a foil.
The boat is very fast and ready for racing in such conditions.

 

upwind is the usual; hit hullspeed, point high, work the waves..

Here are some pictures:

downwind is a blast, the boat actually starts planing(yes it doubles its hull speed which is offically considered planning)

in hectic conditions the foil keeps the stern planted, so far i haven't ever stalled the rudder or lost control downwind!

picasa is shit software for editing photos..

main sail trimm for downwind is something to improove, the spreader is in the way of the sail, and i have no clue how to solve that problem, yet

this is still happening when bearing away..
no big deal though.

this is the new rudder, it is larger than standard, the foil attached is a hq3.5_10% thickness low renolds airfoil originally for model gliders 

previous experimets showed that an angle of attack of 1-2 deg is enough to keep the stern planted, so this 100x60mm foil is tilted 1.5deg downward.

So far so fun, thw boat is showing some cracks around the mast ram, these will have to be fixed before painting.
I am happy with the boat.
I will keep collecting speed and course measurments with the mobile phone inside the boat for the next week or so and come back with another post with a more numerical approach to the evolution of F5g sailing yachts.

new F5g b-rigg

Above is the new b-rigg to be used with wide F5g class boats, it has 3900cm2 of sail, the man/jib ratio is 60/40.
This is the second generation of b rigg, the jib is borrowed from mk1 b rigg. On later riggs the boom will be replaced with a telescopic one.
The main has a shorter foot(5cm), and is 5 cm higher. The area is the same as mk1.
The shorter foot brings the force resultant closer to the centerline. Meaning that the main doesn't put so much strain on the rudder when running.(better directional stability) The shorter sail also makes the boat more agile(force resultants of main and jib are closer together), making it easier to bareaway, and sail the boat downwind with the waves.
The mainsail is higher, to keep the heel angle and speed up throught the luls.
The 3d printed kicker and the stainless spreader make setting the rigg up easier.
Mast bend, when Fila si supported at hull and held horizontally by the tip of the mast(biggest possible moment) is about 4mm   ~ 0   :)
I am very happy with that.

the basic mast curve, depending on the conditions it can be trimmed

Yesterday was the first day of testing.
The winds here in north-east Slovenia are fourious, yesterday the average was 17 knot on the airport(500mm away from the industrial lake sailed), gusting to 25knots

the conditions were abit to fierce for b rigg, sadly the c-rigg is still a work in progress

i bent the mast real good, trimming the sails for speed with a really lose luff

upwind is ok,tacking good, speed is ok, angle not so much
Downwind is a blast

Gusts above 20knts were unresistable, submarining was unavoidable

overall i am happy with the rigg, however i know i have to get more days sailing it

the only really disturbing thing was the main boom dragging through water..

2.nd day of testing.
For this day the forecast was 30+knots with gusts up to 40 knots..     ..this is not very likely, because if a 40 knot gust was to hit the city park, half of the old trees would go down..     ..none of the trees in the park went down and the day is past..
..anyway the wind was to strong to go to the industrial lake, the pond in the city park seemed a good alternative.
The foot of the mainsail was cut and the boom was raised for about 4cm = problem solved

conditions were gusty, there was almost no wave, i could trimm the rigg to deafult settings 

speed dropped compared to the day before, but lots of angle was gained, tacking is spotless

downwind is good, catching the boat going into irons is much easier now

Today the mast prooved to be abit to stiff, it doesn't want to bend in a gust, this is desired to loosen the luff and gain the all important speed.
I have to try with less pre-bend in the mast when the rigg is set.
I recon 10 more hours of sailing with the b rigg in b rigg conditions to sort out the little things are needed.
After that the boat is competition ready.

The little things:
-Mast pre-bend
-Match the luff curves perfectlly
-find ideal main foot depth
-fix spreader and wang rings with super glue

Some clips of todays sailing:

Fila is beating upwind, the speed is good(note the flowers and branches) although it is hard to judge as i am walking with the boat.
In the strong gusts leeway increases and speed is lost..    ..this is predicted, and can not be tammed, yet.
Downwind, the main luff is too loose. I have walk quickly or lightly run in order to keep up with the boat.
The bow is pressed into the water. That is horrible for speed as we know. In the future inverse foiled rudders and forward foils should take care of that.
But for now i am confident that if such conditions appear on the race course Fila will be in the foreground if not even dominant.

Here you can see that the strong gusts are barelly survived. It is also obvious that i have to sheet out after a tack to gain speed. Lighter sails should reduce the speed loss after tacks.
Downwind...      ...ehh, ..    

In such conditions i would always choose the b rigg, to the C, just to get through the luls.

C-rigg comming soon.
That's it for now.

Fila, b-rigg

Back in hometown. It is time to get back online after 12 days of sailing in Premantura, Croatia.
With me was my laser and Fila.
There were good 8 days of wind 6of them with b-rigg conditions. Sadly with no comparison i tried differend settings, ending up with a seemingly good setup nevertheless. The boat is pointing high, and sailing superbly balanced, nearly planning downwind, sailing at about 1.5 to 1.8 times of hull speed.
So now i am really ready to sail well in case of more wind on some of our national class races.

But better than the settings are speed measurments i collected putting my phone into fila, i will speak abou those in another post.
Also an idea for the next generation f5g(national class)boat is slowly taking shape.

Upwind, this is the basic setting i found, from here i give the sails more twist if the wind is in the upper range of the rigg

Sailing heeled, near the hullspeed(according to measurements) nothing special happens, with the future canting keel i hope to exceed the hullspeed upwind

The downwind, where much boat speed is to be gained, above just "shaking" the rudder to get the jib to the other side

Surfing the waves downwind

 

And jibing to get back upwind

The shots below show the boat sailing downwind, in upper wind range of the rigg, with a good setting, and lots of tension on the rigg even in waves nosedives were rare, but inbetween the waves the boat lacks lifting force.
It sails sort of low in the water, increasing wave an wetted surface drag like here:

Obviously a jib providing more lift is needed, in the future i will try something like on a footy.

The second thing is a forward t-foil rudder, the third is a canting keel wich will move, not only move side to side, but also tilt backwards.

That's all for now, i am happy with Fila,

the autum races are getting closer, and i am confident to continue the streak of wins on national regattas, and having lots of fun putting this boat into water wherever there is wind.

Footy B-rigg

Yesterday the B-rigg was finished.
It has about 1080 sqcms of sail, and an aspect ratio of 2.1.
at the moment it works fine, the boat points well and gets up to max speed quickly when sailing upwind, tacks are super fast(becouse of the big rudder) but yet controlable. Downwind it was just a matter of reducing sail area. It needs no backstay as the mast is a hobbyking 4mm carbontube, it has  super thin walls, so it bends under gusts depowering the sail.
On this rigg no ballast on the boom is needed and the total weight of the rigg is 33g.

Here are a few pictures from the pond, when i find the time i'll post some better ones