What grade aluminium are laser masts?

"It can't be done", "It has been done", "Move along", "Use the search". What kind of answers are these to someone posting an honest straightforward question on this forum?

Come on guys. Let's not be smart asses. I know a lot about Lasers and I read this forum a lot, but I don't know the answer to the question. If you know, then please tell us. If the answer can be found in a simple search then please give us the URL for the search. I may be dumb, but I can't find the answer by searching.

It's this kind of one-line, flippant, brush-off replies that will drive folk away from the forum.

I am not Merrily. I am not a Mommie. I am not an official administrator. My opinion has no weight.
 
I know, so much outrage here of late Old Geezer. I get outraged just thinking about it.
Wonder what touchandpass wanted?

Did they want to know how to find non laser materials for a cheap alternative?

Did they want to know what kind of rivets to match to the spars?

Were they making a massive pipe bomb and needed to know the estimated burn/melt time of the alloy?

I guess we'll never know.
 
probably wanted to make cheap knockoffs and sell them to poor inner city children lol
 
Im doing an aerodynamic analysis of a laser using a wind tunnel for a university project, which requires a 1/3 scale laser rig and sail and to scale the mast correctly i either need to test one experimently, or just look up the properties of the grade of aluminimum, and this seemed like a good place to start to find the grade. i guess not, anyway ill just get off my ass and do the experiments.
i did try the search function but didnt find anything useful, maybe i didnt look hard enough.
 
Your aero analysis of the Laser sounds really interesting. Have you access to Aero-hydronamics of sailing by C J Marchaj and High Performance Sailing by Frank Bethwaite? It would be great to be able to compare the aero data in those books with your research. I am guessing you are trying to come up with a 1/3 flexible rig hence the need to understand the flexibility of the mast. You will find that the Youngs modulus for Aluminium does not vary significantly with Aluminium grade. If you measure your mast section diameters and wall thicknesses you can calculate your moments of inertia, multiply by Aluminium's modulus and you have the EI you need. You can then compare your test data to your calculated data.

P.S. I searched for Al grade also and didn't come up with anything either.
 
Clive, yup trying to come up with a 1/3 rig, we did some testing of a mast and found the young's modulus we were getting was a bit lower then the 69GPa that i think is about standard, so thought they may have been something other then standard, however our testing methods werent hugely accuarate. Then used the dimensions to get the second moment of area and hence EI as you said above. Cheers for your help, may see if the librarys got those books tomorrow.
 
Seems the discussion arrived at 6061-T6. See this thread below:

http://www.laserforum.org/showthread.php?t=1422&highlight=alloy+mast


Thanks for your replies!

I want to make a mast because I'm cheap! A lower mast costs about $225. I think I can get a bare piece of aluminum for about $50.

There are lots of aluminum alloys but only a few that are appropriate for extrusion and even fewer that are typically used in sailboat spars. I'm guessing that 6061-T6 is the one but 6063-T5 is a possibility, too. Anyone know for sure? I won't be racing this boat so I don't care if it is legal or even optimal. It would be nice if it didn't break, though!

The dimensions of the lower mast are pretty standard: 2.5" diameter,1/8" wall thickness, 112.125" length. This is a standard extrusion so I'm gonig to guess that they used a standard alloy, too - 6061-T6 is ubiquitous. (BTW: The radial rig is not standard: 2.4" diameter, 1/16" (!) wall thickness, 88 11/16" length - my guess it that this is a Vanguard custom extrusion.)

I'm pretty sure that tempering is a steel thing so I don't need to worry about that. Anodization only affects corrosion resistance. Since I will be sailing in fresh water I'll just put on some wax and forget about it.

Anyone have any other advice before I try this?

Thanks,
--Tim
Click to expand...

Try Private messaging “timhall”

http://www.laserforum.org/member.php?u=1234

he may have cracked it by now.

Literally. LOL

or ring up boatbits (Nelson or Takapuna) also online. They may have some trade in stuff. Also Fosters in Auckland CBD have spar blanks. Also online.
 
Honestly,

If you want to get some interesting data, you may better try a different kind of boat, such as the Tornado whose rig is the most efficient by a large margin, and your data may lead to improvement. Laser level class status wouldn't allow that.

Laser rig/sail is notorious inefficient, it is a basic design from the early 70s after all. Technically speaking Lasers are quite weak, their forte lies in the strong, even fleet.

Just my two cents.

Pd. If you are interested in looking to the Tornados, I can put you in contact with John Lovell (the american top sailor), or mostly, with the world champion Fernando Echavarri.

They may be interested indeed.
 
Hi 'touchandpass',
Here is a reply with an idea to describe the flexibility of the upper mast-section. It is only a model and not the reality (I already have discussed it with Clive, thanks to him). But, you may get ideas to do handle your question.
http://www.laserforum.org/showpost.php?p=7258&postcount=18

Some additional aspects you have to think about:
The full mast of the Laser has 2 pieces. So, there are 2 "J" (one for the upper and one for the lower section and more exact: another one at the area where the mast sections join) and the bending at the point where the 2 parts of the mast join has a kink.

The Laser-mast joins the mast step in a loose way. This means, here is to describe the angle to the side and the angle to the back (or forward at downwind courses) or with other words: the mast fall.

The mast of the Laser gets a "pre-tension" (cunningham{-> momentia of Euler!}, vang, mainsheet ) and also the outhaul has influence to the bending of the mast.

The influence of temperature to the flexibility is an aspect to think about. And also interesting: the influence (a force extra) of the gooseneck to the mast.

Perhaps you do some statistics (testing a hypothesis one-side- / two-side-tests). Contact the local university institute that tests material (f.e. at the institute for architecture, civil-engineering or engineering of machines)


Another idea (not a serious one but I like that model :) ): here is a link to a small model of the Laser; perhaps you are able to get one of those:
http://www.team1newport.com/prodinfo.asp?number=CMILAS

And,
I just remember: "Monty" of "loftsails" in the past made some sail testings in a wind channel. I remember, he had a photo (I can't find it there now), where a model of a Laser Standard stood in that wind channel, during the King of Spain (a big fan of sailing at all) did visited the wind channel of "loftsails". Perhaps, for more information's to that, you better contact Monty direct via his Forum at this website. http://www.loftsails.com/


Ciao
LooserLu
 
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