Pictures of Claudios ZED and pictures of the building process:

claudio 27. november 2001  

Here's my preferred lay-up for a light 3.2 mt F3J model, final wing weight is 1.000/1.050  for a 67 dmq surface wing:

Central panel 1.5 mt, weight 580 gr external 50 gr/mq glass from spar to t.e, external 60 gr/dmq kevlar from spar to l.e., they sum on the spar +/- 1cm area both 45 degrees for torsion double the 50 gr glass on flaps clevises area for +-10/15 cm either side

rohacell 51 2mm thick core, always sand lightly before using it, and make sort of pinholes (like the ones you make to monokote) before using it, as rohacell DON'T breathe out eventual bubbles...and don't forget to make angled sanding all around sheet  to reduce periferic thickness to 0....

Internal 50 gr glass spanwise bias after final trimming of rohacell on t.e. , and reducing thickness of rohacell on spar area.

tip panels, 90 cm w.s each 240gr ca
Tip panels are using no kevlar on l.e area, just 50gr glass 45° ext (doubling at clevises areas as for the flaps on central panel) and 50 spanwise internal..

For spars i use 25 mm mm large spars made of unidirectional carbon termowelded rovings (200 gr/mq) laid in the recess of both mouldings, i use 3 layers full span for central panel, with a 4th and 5th shorter to sum up in the centre (tapering spar).
Same 25 mm large unidirectinal in the tip panels, but one layer full span,
double for 60 cm and triple for 30 cm from root .

Shear web is made of 50 kg/mc termanto (many commercial names...) 20 mm block sanded to thickness and wrapped with 50 gr glass at 45°, carbon braid is better, but more heavy (and expensive too) and probably more suited to a more windy-dedicated model, for wich i do modify external layers of both central and tips to 80 gr, more layers of unidirectional carbon on spar (up
to 10 at central, 7 at tip of central panel) and 3 mm balsa vertical grain each side of termanto before wrapping it all with carbon braid.

I do prefer to lay carbon spars on the mould as they are as far away as possible from each other, and no microballons distance is stolen...but depends on how precisely you are able to make spars outside the wing.....

We had, as always is given , earlier or later, the occasion to study a few write-offs of commercial models, this is good practice for you too, you'll discover a lot of useful hints, which, given the non profit activity that is modelling for fun, can be applied to your own models with a more quality-minded  and less time-consuming thinking ....by the way, burning pieces of scraps from write-offs reveals with a bit of knowledge the layers that were used, glassfibre don't melts, kevlar does, compare what you see with tissues you have and you have a full analisys made....

For pictures on moulding processing you can have a look at

http://www.ifrance.com/am44/INDEX2.HTM

For Suppliers of rohacell, it is a trademark of ROHM germany, a search should reveal you if and who is the trader for your country

As you said this is MINE way of doing it, surely not the best, i am very interested in other people's sytems too.

Bye Claudio (Great english writer...ehm, sorry, if you need i am anyway here
to mess....clarify eventually)
Pordenone, Italy

claudio29. november  

we do use carpaint, poliurethanic two-component paint, actually, which allows very thin layers to be sprayed, what we do to favour anchoring of resin on it is, instead of painting one more layer of transparent (second method in your article) is to gently sand it with abrasibe foam...you know the stuff that is on the rough side of scotch-brite dish washing sponge? that one!

It did work for us, of course this is done carefully when the paint has fully dried, which leaves you your option to make decoration when you're artist-minded, and laying when you're fiberglass-minded...leaving in the middle as much time as you like....:-)

we do lay external skin (layers, peel ply or kevlar hinges, carbon seating...etc.) first with core, BUT not the internal layer yet, tear off fabric should be peel-ply and we use it all around it during this first phase, where non-core edges leave external skin only.

At this stage we sand flush, it's a matter of trial and sand practise, the trailing edge chamfer (all trailing and leading edges were chamfered before anyway, but oversize, now you get to really espouse both halves leaving a SMALL gap in the trailing edge area for internal layers and fillers...), the spar beds, AND the rounded escavation where, for example, the upper lip of the flap is placed, result should be that the lip against which the gap seal works is double layer, internal and external skins meeting at that point with the core thickness reduced to zero in there.

Next is the  internal layer, for which we use a nylon breather material used with absorbing  cotton sheets, the nylon we use is quite different from the peel ply stuff, it is actually a sort of very thin mylar with holes going through each 5 mm or so, we call it preforated, and used with absorbing material (or paper) makes the same function of the peel ply, but nice thing is, it does not leaves the thickness of the peel ply resin,and what's more important allows you to proceed as follows:

cut sheets of preforated two cm oversize to your planform

lay them flat on a table protected with some nylon or whatever

lay the clothpatches on it (both last operations are helped by electrostatic adesion when you do them)

pour the resin, and, using a piece of cardboard spread them until all cloth is wetted and excess resin brought outside

trim the glasscloth to the size of the preforated sheet underneath, it helps to have the light blue colored preforated sheet, you can easily see it through the impregnated glass....

take the full sheet out and turn it upside down in the mold waiting (fibreglass to core faced, obvioulsy)

put a layer of absorbing material and vacuum it up

once dry take out all preforated, absorbing will come out with it, and you have it.

only withdraw is that the surface left by preforated is not suited to any gluing, but we do make light sanding in spars places, and anyway, as internal skins are always so thin, and resin so little, they are plenty of microholes through which resin can go anchoring to underneath material....anyway never had anchoring problems...

internal patches for servo mounting and fixing bolts, and any other stuff you want to vaccum on the inside are put after lightly sanding the interested area, during layup of the carbon tows of the mainspar, which we do lay after impregnating them outside the mould and vacuuming in the mould with LOTS of absorbing material over peel ply.

Then you're again at the stage where you continue...and all the rest is as before.

claudio 17. marts 2002

Yes the model wings and tails are from moulds....strong....well i wouldn't use it in a 7+ m/s wind but i have also to say that it has already raced in a 11 m/s wind with gusts at 15, and did not break...not even bend on launch, but i have to say we used winches that day, so not the power of two man towing...but manage to break 4 times the treated  1.2 mm lines....anyway using it that day did not proved wise, but as i was the organiser of the race i had no time and willing to set the spare model, also because i sold the spare that same day.....:-)
What i can tell you is it is far more strong than a Pike sl, and that was enough for the purpose we look after. Next, almost ready to get out of th molds is the windy version, i am quite curious about what the weight will be, hope in the 2100 gr range, and will be hopefully strong enough for any legal wind, with ballast tubes (the light one hasn't any) and a more sound structure... The main lesson from the guru? 80 gr glass outside skin, 60 gr kevlar where servos openings and seating area, 2 mm rohacell , 1.6 x 28 mm carbon roving top and bottom, , 50 gr glass lenghtwise inner skin, spars made from 6 mm thick divinycell 75 kg/cubic m with 200 gr carbon diagonal on one side, (sort of a sock spar but without the top and bottom part of the sock...heavy), and very, really VERY LITTLE    filler when closing the moulds, just wood blocks where the fuse fixing screws  go through.
If it is worth going to these weights is anyway still under study, as i already told you, still on testing, when i'll have the heavier one i'll tell you if i will just fill the lighter with a ballast tube and use it always half full or leave as it is....what's sure is that it is much easier to use as a hand lauch glider, but may be this is no interest in competition...:-))) except when you have to scratch those few last seconds at ground level....
It is very easy to get up in a thermal, but it is more nervous in turbulence, slower means it gets nearer to the stall without stalling.....and a few other things i still i have difficulty to get used to, so...advantages and disadvantages....all in all my all-time still preferred one was (is) 2.3 kg on 67 sqdm...fast but very effective in competitions...starting to think mh 32 is not a good profile to slow down with lightweights....we'll see.
About koptokaff: 2.8% camber....looks as it would be needing a good elevator surface or a very long tail moment...:-) 74 sq dm on 3300 means also great cords, or no tapering at all, and as i guess the first is the likely to be your choice, i am quite interested in how such a higher Re working wing woul behave....good choice, definitely should be a good project to take with you along with the Trinitus...or to start in the category.
Ever had the occasion to try cnc cut cores? or there is any reason preventing you from using them (inaccuracy or whatever) there is also a site explaining how to make your own cnc cutting machine, doesn't look difficult, having the time to do it and no other source for the cores (both which not applicable for me, i have never enough time and a friend who is doing the wing cutting as a job...:-)

Claudio 19. marts 2002

Hi Erik

in fact so far looked stiffer than i expected....hope not to have surprises with tow men an 1.4 lines....will try very soon. Yes the measure i gave you is actually in the center, at the end of the center panel is 0.8 x 28 (no tapering in center panel), then the end panels start with 0.8 x 28 and finish 0.2 x 8 (tapering both thickness and width). I do not make the spars outside the wing, the ,method i use is laying the external skin and the cores sand in the core the recesses for the carbon rovings of the spar (i do this only on the central panel, there is no way to sand a tapered recess in the tip panels, so in them i lay the carbon tows on the core lay the carbon rovings and the internal skin glue the vertical part of the spars to one side of the moulds trim them to height by sanding them frequently testing with the other half mould close the moulds filling the small gap that is now on one side only

For the vertical part of the spar i use 6 mm foam (kind of rohacell but much much less expensive) with prefitted 200 gr carbon on one side, i made a plate of it in vacuum and roughly cut it to the height i need, then i glue them to one side of the wing (say to the top) with 5 minutes glue, and then trying and sanding them to height is a matter of minutes once you know which is the thickness required...leaving very little to the void for fliller on one side only. For the carbon tows i use thermowelded rovings, they come as a roll of roving 30 cm large on a protective backing tape you take out when lying them, and the thickness you wish, i use 300 gr/sqm, which means they are 0.3 mm thick, what you do is to cut with a cutter on a table the number of strips you need and you're ready to lay them.

I have to get hold of the portable pc so that i can send you some pics of the various phases, it sure takes longer than what i understand you do, i need an evening to prepare the various parts (possibly the evening of the day i painted the moulds:-) then the following evening i do lay external skin and cores, the next i do lay carbon tows and internal skin, the following i put in spars, trim them and prepare and put cables in, at last if i was quick i can close the moulds, total between 4 and 5 evenings for doing one wing (moving quick), reality goes in the middle so i am lucky if i can do it in a week, usually the two phases wich need more one-go time are laying external skin and core, and then laying carbon and internal skin, all the others can be done using spare time here and then....
Next time i'll try to send you some pics of the tail unit molding, it is anyway almost the same than for the wing except that i do use carbon spars outside the core (so that i lay in the order external skin, carbon spars and core the first evening) and then after tapering t.edges testing with the moulds (i always have my cores already roughly tapered on the contour when i lay them, but oversize on the t.e, wings and tail unit alike. i bring them to exact size with the use of both half moulds and sanding block before lying the internal skin....)then the internal skin, and then gluing to one side the vertical part of the spars, timming them and joining the moulds, as per the wing...

Enough, i go to cut the ailerons and flaps of the new one, and make the wipers....:-)