Today busy with deck adjustment with mast step support.
Roof cut-out implemented as well the jib anchoring.
Roof master under preparation in order to make a female mold.
The ‘modern’ roof recovered this morning out of the male mold rather easy but I do not like it very much, for me is too bulky, finally I prefer the original one much more slim and sport like, as per Alfa Romeo maxi yacht.
ClaudioD
PS :
I making a lamination experiment with honeycomb; one glass face at the time. The glass tissue once impregnated, is positioned at the top in order to allow the resin to drop a little along the cells walls.
I am really a great fun of your talent. So far I understood clearly the way you were designing your boats. Now, that I look at pic #9 are you are going to bond the roof fixed? So far I thought the superstructure of your yacht is going to work as a hatch? Correct me if I am wrong.
Thank you Lukasz,
the hatch is part of the Roof as in this previously published picture !
In the present situation, the roof is positioned some 5cm backward from the mast therefore the hatch is moved forward in order to keep access to the servos, battery and Rx, or at least is what I try to do !!!. The hatch is of the same material as the roof.
Cheers
ClaudioD
Today is another “story” : Nomex Honeycomb glass lamination & destructive testing !
Glass lamination is chosen to get better visibility of the cell’s impregnation with the method above described : ‘one side at the time’
Glass adherence rather good, ‘cells edges’ appears to be well impregnated, probably too much . Evidence from the cell’s circled appearance against the original hexagonal form.
Pull test OK, peel off rather difficult and assumed very good.
In spite of that, the relative weight is 8g/dm². The panel is 4dm² and weight 32g
Nomex HC 2g/dm²
Glass 1g/dm²
HC panel surface 4dm²
Normal lamination based on 50/50 would use the same amount of resin as the tissue weight. In this case the resin used is doubled in weight.
Examples
normal expected weight with glass tissue of 100g/m² :
1g x 2 sides x 2 resin amount x 4dm² = 16g
HC 2g x 4dm² = 8g
Total 16g + 8g = 24g
measured weight 32g, therefore :
1g x 2 sides x 3 resin x 4dm² = 24g
HC 2 x 4 = 8
Total : 24g + 8g = 32g (as measured.)
The panel appear rather strong, will see in few days !
My analysis tends to prove that the amount of resin is +50% compared with a normal glass lamination of 50/50 and the weight of 8g/dm² is of course not negligible in spite of the sandwich strength !
Finally I compared two similar supports :
The carbon sample is of 1.2mm thick weighting 5.15g and the honeycomb sample is 3.5mm thick weighting 3.0g.
Torsional and bending resistance slightly better for the carbon panel. Compression resistance the same.
To note that the glass lamination is only 0.25mm thick per side against the 1.2mm of the carbon panel.
Another weight comparison with my retained servo mounting :
Of course to mount two servos I used a plate instead of two beams . (simulation of course )
My impression is that for little supports there is a definite advantage in terms of weight gain, while with the the above example the weight gain is not evident !
Further to increase confidence on the bending strength the carbon tissue will be welcome and the weight will probably be slightly higher.
I stick to my beams !!
After 2 days waxing with mirror glaze 16, the Roof is finally laminated !
Hope will be not too heavy compared with the 20g removed from deck cut out !
ClaudioD
PS:
Roof de-molded ! just 2g heavier, I’m glad. Before deck/roof bonding the weight is still around 82g
CD
It only seems like yesterday that you took the decision to ‘scrap’ the first hull, and to look at what’s been achieved is truly phenomenal. The only point that I keep thinking about is why two winches. Obviously, if you’re keen on experimenting with overlapping genoas then it makes perfect sense - although I feel it’s an added complication which may not be wholly necessary. That being the case, a single winch giving a lighter weight (considering the winch & ancillary components) is surely the way to go. You may then bring the project in below 4000g!!
In the meantime, fantastic progress and I’m looking forward to the future installments. For me, I’m beginning to regret the train set for sons birthday - whenever there’s a problem (usually de-railment) it’s closely followed be a very loud ‘D-A-D-D-Y’, which is fine, but not at 5.15 am! I’ve also found myself roped in to building railway related buildings (loco sheds, signal boxes, bridges - you get the idea) which all takes time…
Hi Row,
I remember similar things of many years ago, my son in now 46, this happen at Christmas. Very enjoyable anyhow !
Many modelers, including myself, would like to experiment independent adjustment for Main and Jib as on real.
Of course ‘presetting’ the jib boom is what it is done all the time with ‘classic rig’ and also with the ‘swing rig’, is that the real good solution ?
As you say, I give a try, knowing perfectly that the extra 65g could help a lot to stay close to 4000g. This is my Jolly !
BTW the 2 winches are similar in weight with the RMG 280 !
Today busy with Fin Box bonding and mast support bonding including the relative alignments. Bonding on progress !
May be, later in the day, I will bond the new Roof to the Deck, Olympic Games permitting !!
Just my opinion, but I am not happy about the design of the rudder. I think it will cause lots of drag due to turbulence at the tip and the cut away at the hull will allow cross flow as the pressure is able to escape.
I think it would go faster with a (less sexy) simple rectangle shaped rudder with the bottom edge horizontal to the water plane, and the top edge angle fitted close to the hull. Almost all the top IOMs have gone to a simple rectangular rudder.
There is always a good reason for the way you do things. I guess it’s called experience ;). Some elude us more than others! Like, why do you bother yourself with the flat deck while bonding the mast support? Don’t it gets in the way when you glue the thing in place? Using a temporary maker brace of some kind, if you need the location of the hole for placement, seems less troublesome. At least for someone that don’t have its hands on it.
Just a thought, but for independent control of the jib you could always go down the route of a single drum winch (for main & jib) with the jib sheet passing through eyes on a smaller servo arm on its way to the fairlead to allow fine adjustment. Research has shown that it’s quite a common arrangement on the EC12’s.
Hi Row,
now that you refresh my memory, is very true that a small and lighter servo could perform a jib boom trim. Let me see what I can do !
Cheers
ClaudioD
Hi John,
according to my readings about naval architecture, the elliptic shape is the one that offer the best efficiency in the lift/drag
ratio.
Many books report the same shape and they called 1/2 or 1/4 ellipse. I do not know how much Reynold and speed are entering in this choice.
Being the 123 a prototype, I do also have margin for experimenting what book reported. IMO, IOM is not a reference !
Here in the picture the two rudders actually available, both having the same surface. According to theory, the longer should offer the best results.
If I remember, the AC of 2007 used similar shape and much more deeper and not squared ones.
I do not knows if this is true also at the speed of our models. BTW , I believe also that our models are proportionally faster then the real ones.
i.e. a 1mt boat sailing at 1kt should be compared with a real one of 10mt that should sails at 10kt and this is probably not true.
Having justified my choice, only the water tests will be telling if was a correct one. This type of rudder is very common with Class M.
Remember the Hurricane ?
Cheers
ClaudioD
The flat deck has also a precise hole where the mast tube pass trough.
Was easy for me to use the deck as a guide to center the mast support. Not to forget that a pseudo mast tube was equipped with a lead and string in order to help the centering. The deck was a nice tool to obtain the centering.
While using the deck laminate as a guide, the mast support was already prepared with charge epoxy and therefore ready for bonding.
The Deck laminate was then recovered to bond the Roof, see picture made some minutes ago. Tomorrow I will try to do better !
OK, I think I understand now. You didn’t had to do acrobatic moves while applying the epoxy through the deck hole. The expoxy was already there when the deck was put in place, not cured yet, which still allowed fine alingment tuning. Right?
Hi Sylvain,
exactly, the resin was not yet cured when I put the deck onto and made fine alignment observing the lead position along the false mast, while the ‘water level’ was checking the horizontal axis. picture 123-570.
You may notice that the balsa stern has been cut out, it will be replaced ply a more solid material like laminated sheet or 1mm plywood. It was there to keep the hull shape at the rear.
Here the back-stay attachment and water tap shall be integrated too.
Today I will try to take care about the jib anchoring location. Not really easy since I want to keep the anchoring eyelets recessed from the deck/hull sheer line in order to reduce the distance between the deck and jib boom.
