Thought I'd share this one. Recently got an AL360 E3 slalom 190-245 which has a 15cm width tail. My old Fiberspar 220-278 has a 10cm width tail. I tried my F2011 8.6m on the AL360 and found it has as much low-end power as my F2010 9.5m/Fiberspar combo. This is down to the wider tail. So I decided to make a wide tail for the Fiberspar to get extra grunt out of the 9.5m.
MK 1 version was a bit crude and only took one afternoon to make, but its solid as a rock, but Im going to make a second better verion.
I got hold of a 48cm tail end from a smaller old Fiberspar wave boom. I cut of the original tail end of leaving just the carbon tubes.
I cut a narrow slit in each tube large enough to slot in a piece of alu carpet plate. I then secured it to the carbon rods with a couple of self tapper screws.
I the proceeded to wrap plenty of uni directional carbon mat around it and tightly wrapped gaffer tape around it to get a nice tight lay up. Gaffer tape removed once cured.
Just needing sanding to smooth off and pulleys fitting.
MK 2 version is being made with a 58cm tail as I did loose a bit of stiffness on the MK1 due to the tail only being 48cm. This time round, I am using a piece a 16 x 45 x .5cm alu. I was thinking of getting two alu tubes welded on the ends at the correct angle and just slot it over the carbon arms and drilling and bolting it in place. But just repeat the original process with carbon layers, not sure as yet.
My question could be a bit naive but what the tail with to have sail power ?
What is the advantage in wider tail section ?
Hi Mark,
Nice job on the DIY wide tail, good to see you taking the bull by the horns and making your own performance improvements.
Be careful of galvanic corrosion between exposed CF and aluminium. This will weaken the bond over time and the presence of water accelerates the process(even if it looks fully sealed pinholes can exist allowing water entry). If you have only used aluminium as a core to lay the CF over it might not be a problem, as long as you are not relying on the bond. It is best to pre-coat(and allow to cure) any aluminium to create a seperation. Another option is to make a pre-fab CF/foam core panel insteady of the ally...
Ah, I didn't think about corrosion, maybe alloy is'nt the best option. I might use a thin piece of ply or PVC instead. I guess I can pre-cut it into better shape as well. I'll post pic's when its finished:)
Over here Bender has been experimenting with the same thing, he's found there's much more force on the tail piece than you'd think, it has to be a really strong job.
That's very true, don't fancy the boom failing and making a nice big hole in my 9.5m:(
The MK1 version was only used for 5 or 6 3 hour sessions, but it did feel solid as it has a lot of carbon on it, not sure how it would feel after 12-months use though. The pulleys could do with being fitted better. The boom arms had a bit of flex due to the new tail being only 48cm and not 58cm, the MK2 58cm version will sort that out.
I rushed the MK1 but will spend more time on the MK2 as I want it to feel and look good. I have a few ideas on construction and Im still deciding which way to go. Still debating on what to use as a core, alloy (sealed to prevent corrosion), ply wood cause I could shape this or PVC tubing (to look similat to the new NP X9)????
Doesn't galvanic corrosion occur between metals? Carbon fibre is not metal and I have never heard of it causing something else to corrode?
But it is hard to get a permanent bond between ally and epoxy resins as the oxide layer prevents proper bonding. Even if roughing it up well or etching, it can still form oxide later due to water ingress. Not a big deal if it is wrapped with enough fibre/resin (of any sort) to rule the alloy centre as not essential for load bearing, but then the alloy is redundant and may as well be a section of a pencil, banana or garden hose.
But why not just use carbon tube? There are enough broken booms around that you will find a length of tail section. The ideal thing about carbon tube is you can properly bond it to your boom with an adhesive resin like garden variety Araldite and have it bloody strong before wrapping with fibre/resin.
Wiht your centre crosswise section, I'd fill it with epoxy/wood dust mix which makes a ridiculously hard filler. If worried about weight, then just 1cm of each end and the centre where pulley/cleat bolts on.
Then shape the ends to fit (half round concave) so you have a lot of surface area on the ends now, then glue onto boom with araldite.
That alone would almost be strong enough, once wrapped it would be mega strong
Just thought from someone who has chopped off boom heads and tail pieces himself but then found it awkward getting a good neat strong job attaching to the tube again.
A simpler way may be just to cut the tail piece in 2 down the middle. Easy to do with Fibrespar as it has 4 pulleys, 2 each side with no central one. Then add in a 5cm carbon plate fillet in between the 2 halves.
Select to expand quoteMark _australia said...
Doesn't galvanic corrosion occur between metals? Carbon fibre is not metal and I have never heard of it causing something else to corrode?
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/quote]
Do you remember pulling old batteries apart Mark? They had a carbon rod as the anode in the centre.
Yep you definitely get electrolysis between carbon and metals, not sure about all metals, but certainly with ally.
I had a 2nd hand carbon boom that somebody had "repaired" with an ally head, after I'd had it a year or so the ally had virtually disappeared inside the carbon arms.
I wouldn't consider using the 2 together in any circumstance!
If you really need to laminate carbon over aluminium.
You need to etch the aluminium with sandpaper after you have smeared it with an epoxy adhesive made for metal/composite bonds (typically a rubber toughened adhesive) SP/Gurit spabond 345 or ATL Composites H15/R15. This way no oxygen gets to the metal surface. Next wrap metal with a light layer of glass (This insulates the carbon from the aluminium) then laminate carbon.
Decided how Im going to do this. I'm going to use perforated alloy sheet to bridging the two arms together.
Basically, I'll use a piece alloy perforated sheet 160m x 40mm x 1.2mm and wrap it tightly around both arms to form a bridge. Then I'll seal it has Brad1 describes.
This is NOT going to have just a few layers of carbon on it, its going to have LOADS of layers as I really do not want this to snap. If it snaps, it will kill the boom. Will upload stage pictures over the next week or so.
I'm fairly confident that this will work (I hope). But this time tomorrow, I might have decided to do it another way:))
Galvanic series given below - combining the elements with most separation will give most galvanic corrosion:
^^^ Yeah agreed (after my fk up lol)
And if you dont want to buy pultruded carbon sheet / rod / bar, just laminate carbon cloth x3, thin balsa, then carbon x3 again about 4 or 5 times and stick something heavy on it. Voila - 10mm thick sheet that is stiff as blazes.
PS explains why my carbon / Ti creations were OK
mmmm, now I'm doubting using any alloy. I only have one spare Fiberspar tail so I'm going to play it safe and use a 2mm thick carbon sheet to bridge the gap between the two arms.
Will cut it with a slight curve to increase the clew length and to give it a bit more of a professional finish.
Will use plenty of carbon layers wrapped around the arms and the bridge section to unsure its strong and stiff.
I just need one bit of advice, attaching pulleys. Will be best using regular steel bolts to attach them?
Spoke to MB Fins, they make custom wide tails and it would cost about £350 uk with taxes, duty etc, and I would have had to post my Fiberspar tail to them:(
Here's were Im up to so far. Decided to make the tail-end on carbon tubes so I can slot the unit onto the two carbon tubes. This way, I don't have to cut off the existing tail-end until I am 100% happy with the new tail-end.
I used the arms of an old broken carbon boom for the two tubes, cut to 5cm long. The tubes are a very tight fit on the Fiberspar tubes. The gap between the two 5cm tubes was bridged with a 50mm x 160mm x 2mm piece of rigid carbon plate.
Iv'e mounted the tail-end onto white alloy tubing to keep things lined up. Once completed, the tail-end will slide of the alloy tubing, then I just need to fit it onto the fiberspar tubes. Pictures tell the story better than me:)
So far, I have used 5 layers of uni directional carbon. Will continue to build these layers until it is around 1cm thick. OTT, but feel happier with this.
Oh, forgot to mention, when its completed, I might make a mould for it so it'll be easier if I decide to make any more. But that another story I guess:)
Nearly completed. Not looking pretty at the moment, but after a serious sanding session tomorrow it will start to take shape (thank fook for power tools), then one layer of carbon applied very neatly to make it look pretty:) It feels very strong, and I'll be very suprised if it snaps/breaks.
I'd bog it before sanding, then the final neat layer. But it's looking really good.
Any body thought of making the front wider as well?
I'm thinking of a 12% thickness to chord ratio speed sail, but none of my booms will handle anything this deep, even with the back widened.
i sort of widened the front of my carbom boom. it snapped one day right on the front next to the clamp so i used a bunch of different sized carbon tube i had hanging around to make a solid carbon rod that fitted right through the whole front of the boom at this point i thought that i would make it a little wider than it was originally so i glued the rod in and made it a length that made the front a bit wider (not much about 20mm but same method could go bigger) then after the glue dried i bogged the gap and once dry sanded alot of the boom on and around the area of the join so i could put a thick layer of fresh carbon wraps over the join and still fit my boom clamp over
i have somewhere between 5 and 10 sessions on it will a few good crashes in epic conditions and it hasn't moved so i'm happy with it and my confidence in it is growing
Ahh Bog, that magic stuff.
I'm surprised this is an Australian-ism, thought it was a universal term.
Guess it started in the panel beating industry, some sort of putty to fill gaps/holes, and very sandable.
I add something like "q cell" to resin to make a light, thick, spreadable mixture. It's then easy to sand that back smooth without removing any carbon.
Job done:) Any ideas on the best type of glue to use to attach it to the carbon tubes. I'm guessing that regular resin could slip and cause the tubes to twist. The original tail end was glued by fiberspar and it was rock solid. Would love to know what they use?
Any quality epoxy adhesive resin. (Your laminating resin is not the best as an adhesive). I would be using 24hr stuff though, not 5 min araldite.
If there is more than about 0.5mm gap all round, I'd use JB Weld as it is a bloody good bond but will also fill a lot (quite thick)
Given the taper it is not taking a lot of load?
