Home building a mast..

For those who are dreaming about building an F16 in a remote corner of the world and have trouble finding masts. This thread in the builders forum could be worth to watch.

http://www.catsailor.com/forums/sho...4&an=0&page=0#Post134804


We are using cut down Tornado masts which we will move the fittings on to suit the F16 sailplan on our boats. But if it is possible to build a wood mast at the same weight as an alu mast, it opens some very interesting opportunities.

Yea, I think we should change the rules to make wood mandatory. Oh, don’t forget the bamboo sails because we can’t leave out that technological leap.

Hey, dont knock wood <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Yeah

Timber - epoxy hulls here mate and still going strong !

Wouter

wood is so 1930s.
Haven't you heard that most big manufacturers use 400lbs of epoxy these days? It is the "new" thing. wood would keep things too light <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Bamboo is being used for flooring, socks, blouses and who knows what else. Why not hulls, sails and masts! <img src="http://www.catsailor.com/forums/images/graemlins/shocked.gif" alt="" />

Talking about masts, the same could be applied to beams I think.
I remember paying about US$300 for two alu beams for a 16 foot cat 7-8 years ago. For that price I could build composite beams instead. Just need some engineering done first, any volunteers <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

Hi Rolf,

have a look at http://shop.ezentrum.de/2461261/sTVeLqG5...amp;artid=71646

It is in German, but it is a CFRP tube for about 150mm diameter and 5m length, or not other crossections with same perimeter. It gives you a nice +-45 basis (which shoud be topped by some UD cloths). It is certainly not the cheapest shop, but it gives you an idea (it is certified for aircraft structures). Correctly done you dont need a dolphin striker = less nasty drilling in CFRP. Regarding engineering: Well I cannot give you full engineering support (but do you relly need it?), but some stress calculations, sizing and so on. But not within the next two weeks. Just let me know.

Cheers,

Klaus

Even better, I know a hippie that can grow some hydroponic bamboo. It will be so strong NASA will be calling you.

Aren't the re-entry shields on the Chinese space capsules made of balsa? Don't knock wood.

Sign me up for that re-entry...NOT!

How do you like your Chinese; rare, medium or well done?

Actually the "re entry" surface "tiles" used by the old USSR on all their personnel carrying orbital vehicles was/is wood. It is only used once then completely replaced and is very effective and cheap (apart from being non reusable). The first shuttle for the USA was for some time before it's completion also going to use wooded tiles until they came up with a much more expensive but reusable "tile" system. It has been said that if NASA had/did use wooden tiles there would be a few astronauts that perished still alive today.
(The tiles are, I believe "cork" so "Corksfloat" is very appropriate?)

<img src="http://www.catsailor.com/forums/images/graemlins/smirk.gif" alt="" />
In real world it is some combination of phenolformaldehyde fibre and resin. No wood hard enough in our forests.

Actually, the use of wood and situations of heat/fire is actually largely misunderstood by the main populace. What else is new here ?

For example, Firefighter prefer buildings with timber trusses over steel ones. The reason being simple. It will take a very long time for a thick timber truss to burn through enough to fail. Steel and aluminium versions can weaken and bend or fail within minutes.

This effect is caused by the fact that wood chars up on the outside isolating the untounched timber on the inside and the fact that timber is largely insensitive to heat and conducts heat very badly.

Basically the core of the thick truss remains largely unaffected for long times of directed heat influx.

Metals conduct heat very well and will soften up quickly when heated up. As soon as they have heated up they will deform, bend and break bringing down the roof or walls.

The fact that Timber trusses need to be much thicker then the steel variants in order to carry the same loads actually increases this difference in behaviour favouring the timber trusses even more from the perspective of maintaining integraty under fire.

Someone said to me several years ago. "If wood was discovered today then it would mean a revolution in material use."

And it is indeed a largely misunderstood material.

Wouter

there you go

if you home build your mast out of over sized section wood , you keep it in your garage over the winter which catches fire , you can be happy in the knowledge it won't bend or melt bopping the fire peeps on their heads <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

I prefer my mast made of carbon from wood compressed over millions of years(or wherever the carbon comes from ) and knitted into a new shiney stick, which I expect would burn like it was going out of fashion (the epoxy that is ) .after the fire reknitt the carbon and remould again .

When I was at JP's place it was amazing to see the rolls of prepreg carbon in his freezer which can quickly be transformed into a lightweight mast ,

anyone want an alluminium saarberg A class mast still like new ! , unfortunately the West Epoxied A class hulls burnt rather well after a hard life !

Now that is what I call forward planning! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />
With all the ridicule, I really hope Gato pulls something good off <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" />

I read here some while ago somebody said he used less epoxy to save the environment. If somebody is caring about the environment then have a look at the process of producing carbon fibre, it’s absolutely eating energy...
http://pslc.ws/macrog/carfsyn.htm
It’s not the same thing that the carbon the blacksmith use in his forge...
<img src="http://www.catsailor.com/forums/images/graemlins/smirk.gif" alt="" />

Unless you have a huge amount of hydroelectric power available. Loss during transfer of electricity is a problem, so runnin a carbon fiber production plant close to a hydroelectric dam makes sense. The same thing is done with aluminium plants here in Norway.
Only problem is that they are building lots of new transfer lines to export electricity now, as the price abroad is so high that it justifies the loss during transfer (which again raises prices for electricity here in Norway, both for the industry and regular people)..

There is a small flaw in your soup Rolf. Even close from a hydroelectrical plant it’s not wise to produce carbon or alu. in execs. The energy could be used for something more useful and the price kept low...

With respect to aluminium this only applied for produce NEW aluminium from its ore (Bauxiet).

Recycled aluminium is MUCH less energy intensive. Interestingly enough recycled aluminium is practically undistinguishable from new aluminium even after having gone through many cycles.

That is why recycling aluminium (soda cans) is such a wide spread activity.

I keep saying it. Aluminium is a pretty wonderful material. Only it low 0.2% yield stress limit is somewhat of a party pooper.

Wouter

I am not certain what you mean by that Gato? The alu is not made for the domestic market but largely shipped abroad. Shipping rates are good compared to other transport methods so it has been quite good business. With the new transfer lines and increased prices abroad we are loosing both jobs and business at home. The only ones who makes money on this change are the people owning the power plants (which use our community resources like water and mountains to produce their electricity [socialist indoctrination shining through]). Was this what you commented on?

I was commenting on producing aluminium, that is in many cases a quite unnecessary thing.
On top aluminium is not a very good material when it comes to some things that has to do with boats.
The main reason why it’s used is the fact that it is a lot cheaper to fabricate things from than many other raw materials but can be sold at the same price or sometimes even higher.
Just as an example, masts, a wooden mast is out ruled by the fact that it is involving too much manual work to produce it, and you can not make a lot of profit selling it. Still I have the feeling that it can mach an alu spar in performance.

Ah, but so heavy, Gato is planning to lose few kg's with his ply/epoxy mast when comparing to wing aluminium section <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />.

I was wondering how long you could resist Valtteri, I know you are really happy about having 5-6 kgs of corrector weight on top of the main beam, even if it’s recycled sodacans...

Not to spoil the "corrector weight" party here, but the measurements supplied to me are in direct conflict with eachother. As a result I'm not convinced that the weight measurement is correct itself.


Now I like wood/timber but their ratios of "strength to density" and "stiffness to density" are lower then those of aluminium ; as such I don't see how a pure wooden mast can be superior in weight when having the same specs regarding strength and stiffness as an aluminium version.

Glass fibres share the same stiffness and density values with aluminium, but have a much higher yield stress limit. So by using that you can make a lighter and more flexible mast that won't break but I'm not sure that that is advantagious. I personally found glass masts to quickly resort to pumping on my landyachts. A combination of glass and wood will not be much differ in this respect unless significant amount of wood is used making the mast heavier.

The only real attractive option is mating timber with carbon fibre and I do expect some good results from any projects in that direction. Especially when thinwalled ply is used here.

Wouter

Did you take the sandwich construction of the wood mast into account in that comparison?

I am a bad guy, there will be carbon involved... <img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" />

Rolf,

Yes

Wouter

Gato,

I'm thrilled to learn you go down that route.

I'm very interested in the results that you obtain that way and I have very high regards for the spirit to just try it.

You there are no other objections then I suspect that putting carbon on both sides (inside and outside) is best when compared to putting the same amount of carbon on only the inside or outside. I say suspect as I haven't done a more thorough analysis in that aspect yet. My expectation is that you can then get away with a significantly thinner ply wall. You be stressing the carbon fibres maximally but it is said that you can do that with carbon without much ill effects.

Best of luck !

Wouter

It wasn't measured with professional scales but even if it would be few percent off it still weights a lot and it doesn't change by using professional scales. I trust my scales more than your math based on these two and another mast that had smaller wall thickness, so there is too much unknown in it to draw any exact conclusions.

IMHO alu is only good to save some money (not even that much) when comparing to a carbon and building your own wooden one does that even better.

But the carbon will not be used for cosmetic purpose, the last time I putted it on the inside...

Phill has made one using 2 mm ply, UB and BX carbon, that the all I got from him no more <img src="http://www.catsailor.com/forums/images/graemlins/frown.gif" alt="" />

Come on !

I also gave you a series of actual aluminium tip weight measurements taken at the time our F16's overhere were all officially measured by a ISAF certified measurer. I also gave you several weights of bare sections we weighted.

If our identically shaped and fully fitted alu masts, incl. halyards, have tipsweights in the range of 7.8 to 8.2 kg then how on earth can your bare alu mast section weight 19 kg and have a tipweight of at least 9.5 kg without any fittings or halyards included at all ?

That is not math, that is common sense saying that something very weird happened somewhere. Now I for one don't believe that the aluminium alloy suddenly increased over 30% in density for your mast alone. We checked compliance in crossectional shape, so that isn't the cause either.

Now I still want to find out what really caused this weight measurement that you are upset about. If anything we can make you happy again and address the situation techically (new mast die ? lay claim at producer ?) if that is required.

The most logical culprit at this time are your scales or your method of weighting.

<img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />Either that or some 8 people in 3 different continents measuring about 10 different masts over a time frame of several years did all make the exact same measuring mistakes to arrive at very similar values. Not to mention the guys in the official engineering literature all making similar typos with respect to aluminium density and the way to calculate the total weight of thinwalled extruded sections. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Nahhh !

Wouter

No cosmetics, but increased resistance of the wall under buckling failure. Very important in masts.

Wouter

The plan for the spar for the mini is to make a “box” with ply on both sides of foam that will go from one side to the other of the mast and some UD carbon on the inside where the box meet the sides.
On the outside UD carbon and BX glass or carbon. There should be no problem as the fibres are not in the same direction.
With the rather small cross section of the F16 spar I don’t think I need to make transversal walls.

Wouter,

You assume that the only difference is 15 % of wall thickness, I guess that with that difference you can have also lot more alloy in some parts of the section. As I said before I didn't do weighting with professional scales but I trust them more than your calculations where there is too many unknown variables. I'm planning to weight it better though when our season starts in few months, so let's continue with carbon alu differences then.

For now I'm disappointed about not getting a carbon mast because clearly there is big performance difference i.e. lot more in weight difference than 4 kg's when comparing carbon to masts that we have here. As a engineer you should understand that dragging those extra kilos high up in the air is not that wise and percentage in weight difference is more than in price <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />.

Come on Wouter,

There is over 15 % difference in mast wall thickness and you assume that the masts are otherwise identical? It's easy to slip 1 kg more alloy for example to reinforcements and sail track if you already slipped 15 % more to the wall <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />.

Let's continue this when I have properly measured the mast when I have access to better scales in few months.

What’s the min tip weight? Just to know if it's of any use to taper. Want to keep the center of gravity as low as possible. <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

We have discussed alu vs. carbon masts under the F16 rule a lot earlier. There is not more to say about that.
It will be interesting to see what you find out about your alu masts. Extrusion or a bad weight.. Myself, I am very interested in finding out how thick the "core" in Gats F16 mast is going to be.

If I recall.. Bethwaite had wing emulating wooden mast on his 1970s world title cherubs. Werent wings but a D shape... Construction methodology may be found in his book or online perhaps in the Cherub webpages.. Suggest the UK one before the Au ones.. I do recall them being stripped so perhaps western red cedar and a white pine?

The issue was they were so stiff for and aft they had to have slots cut into the front to allow them to bend. Worked well but eventually the slotted areas just popped out..

ps one can get aero-grade ply in 1mm!!

Stewart,
I think I used 1.5mm hoop pine ply.
I made it by having a cedar backbone 33x19 tapers into provide the leading edge. A spacer of 1.5mm ply and cedar inside and a cedar trailing edge. Just form the shape around the spacer and made a carbon tube which I routed into the back end to take the sail bolt rope. Just cut a slot with diamond saw. I even had a tricky little sealed grove in the trailing edge of cedar so the halyard come down the inside of the mast and still keeping it sealed.

The mast I made was only 6m long, Carbon inside and out, cost $300AUD. I weighed it and did deflection tests on it and compared it to a 6m long superwing. about the same. But never sailed with it as I made it for a friend.

I'd have used 1mm if I had it.

http://www.boatdesign.net/forums/showthread.php?t=14714

Yes, please.

Again, I really want to find out what happened here as I may well have access to adressing the cause of this issue if indeed it is related to the production of the mast section. It is a serious possibility that a new F16 alu mast design and new die will be made then.

Wouter

Gato

http://www.formula16.org/content/view/13/36/lang,en/

1.4.5 The weight that is measured at the mainsail hoist height of a mast lying perfectly horizontal with its base supported at the bottom edge of the mast section is referred to as the "mast tip weight". The minimum mast tip weight of a fully fitted mast, excluding standing rigging, is set at 6.00 kg for reasons of seaworthiness and to guarantee fair racing.


Standing rigging is defined as sides stays and forestay. All the rest remains on the mast, that includes for example shackles used to secure the stays to the hound fitting.


7.17 Standing rigging

All the stays connected to the mast, excluding the diamond wires.


Just as additional data; ISAF certified measurer has measured 7.8 - 8.2 kg tipweights on alu superwing F16 masts. Carbon masts typically are down to what is minimally allowed 6.0 kg although exceptions to this rule of thumb have been measured.


Taper won't help you much in the weight department, it can help in the way of sail shape control in thetop of hte mainsail however.

Wouter

Not so much in weight no, but if we speek of heelingmoment ther is some multiplication to do

sounds interesting..

I now believe Nicole's mast was western red cedar backbone and balsa aero-front.. Finally found some old pictures of her 76 world championship winning boat..
The bolt rope was routed if I recall into the flat back of the cedar.. But to be honest that could be incorrect and the picture doesn't suggest..

I spoke recently to the last Aussie C wing designer and he suggested he would do a ply wing mast if there is ever a next time.. So maybe your onto the next big trend.. *smiles*

I also can't recall where I last saw the ultrathin aero-grade ply.. Think it was at the local hobby shop.. Used for model gliders and planes..But the issue will be scarfing 1 mm thick ply!! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Wing designer, as in wingmast or as in C-cat full size wings? If the latter, put him to work on documenting everything he knows on the subject! Better put him to work on documenting anyway. What would it take to get him to do it?

That sounds like an ungodly amount of work to do right. When you are all done the you have 1 mast that in all likely hood is not quite what you really want.

Why not build a gypsum/screed mold and lay up a traditional full carbon stick? The process for the mold is very simple to do at home and could be used for several attemps to dial things in. The actual mast build process is fairly straight forward as well. The biggest A class mast builders do not use autoclaves, even though ideally they should produce a slightly better finished product.

Well there are a lot of ways to approach the problem. I guess that if you were rely looking for a super spar in wood/carbon the best thing would be to opt for a technique that in French are called “bois moule” (sorry for my spelling). You take rely thin strips of wood, almost like shavings and cross laminate them at 45 deg to the length axe of the spar (on a male mold) like when you use BX 45 deg carbon. Like that you have the wood fibres orientated in the most favourable way. On both sides of that some carbon UD and eventually some 0/90 deg cabon (This is only guesswork).
But for my purpose this is too much work.

barlow built some awsome ply / epoxy / glass / carbon masts about 20 years ago; they were truly things of utter joy.

Could one of the people who know, Phill, Wouter etc. Please post the moments of inertia for the "superwing" so I don't have to start from scratch if I develop a laminate spec for Gato.

http://www.composites.com.au/

there are some wing mast section properties in their products section...the AC145W is the A-class one (60 x 145 mm, 167 x 37.5 cm^4 (although they have an equivalent aluminium second moment of area value too?)). Weight of 1.29kg/m.

Although not of the same scale, during my model multihull building phase a few years ago, I built some very simple carbon wing masts of up to 1.8m (about an inch of chord length). They were great! Extremely stiff and easy to build, not to mention more durable than the equivalent aluminium ones. They were a similar weight.

It's good to see ppl willing to try building their own carbon masts. I may be convinced to give it a go sometime (just sketching up some ideas now).

A thought just came to mind while designing Gato's mast. When the "tip weight" criteria was added to the mast rule what calculations were done in determining a suitable number? The reason I ask is concentrated point loads can have a big effect on the mast's dynamic behavior.

Don't know, although I think the starting point was a standard taipan mast configuration.