anderswallin.net

The people at EMC2 Fest (webcam here) made this AVI of 5-axis machining a sphere using some custom g-code and povray.

I’ve been playing around with vpython, so you can expect some CAM-related posts on drop-cutter in Python and associated 3D views or animations in the not too distant future.

A simple pystone benchmark using the python multiprocessing package. Seems to scale quite well - guess how many cores my machine has!

" Simple multiprocessing test.pystones benchmark "
" Anders Wallin 2008Jun15 anders.e.e.wallin (at) gmail.com "
from test import pystone
import processing
import time

STONES_PER_PROCESS= 10*pystone.LOOPS

def f(q):
    t=pystone.pystones(STONES_PER_PROCESS)
    q.put(t,block=True)

if __name__ == '__main__':
    print 'multiprocessing test.pystones() benchmark'
    print 'You have '+str(processing.cpuCount()) + ' CPU(s)'
    print 'Processes\tPystones\tWall time\tpystones/s'

    results = processing.Queue()
    for N in range(1,processing.cpuCount()+3):
        p=[]
        q=processing.Queue()
        results=[]

        for m in range(1,N+1):
            p.append( processing.Process(target=f,args=(q,)) )

        start=time.time()
        for pr in p:
            pr.start()
        for r in p:
            results.append( q.get() )
        stop=time.time()

        cputime = stop-start    

        print str(N)+'\t\t'+str(N*STONES_PER_PROCESS) \
              +'\t\t'+ str(cputime)+'\t'+str( N*STONES_PER_PROCESS / cputime )

I remember a quote from MMI some years back on the IOM “there’s nothing wrong with it another metre wouldn’t put right!”. Well the days of the A-boat and 10-Raters are pretty much gone in most countries, and now there are a number of sub-1-metre boats or kits becoming popular. Some are popular in great numbers, like the Micro Magic (see my post from Feb 2007). Here are two home-built boats/boat-types I’ve been notified of lately:

This one is 750 mm long, comes from NZL, and is called a Racing Sparrow. The website looks exceptionally good with a lot of information, pictures, and downloadable plans. Designer Bryn Heveldt has also written a book, available on Amazon, about building the boat. There’s a YouTube video here.

This is a Strathclyde 70 class (does the class have other ‘homepages’?) boat, also around 700 mm long, planked in balsa by Peter Trimmer (AUS). It’s actually a 70 % scaled down version of the Laerke IOM.

I wonder how these boats sail? I’ve sailed a MicroMagic a couple of times, so if anyone can comment and compare these two to a MicroMagic or an IOM I’d be interested. Do people really want the 1+ metre boats, or is racing just as fun with a smaller cheaper boat?

As before I would predict that any class that aims to be popular needs to have good availability of boats. There are a lot of MicroMagics and RC-Lasers around because you can buy them (more or less cheaply) over the counter at the hobby shop. It’s just a shame that usually the designs and class rules of home-builders and accomplished radio-sailors (you know, the ones who still have their A’s and 10R’s in the basement) seldom meet with the needs/requirements of people who are able to mass-produce a boat. I think currently there is no commercially mass-produced kit or ready-made boat sold that fits in any international class (A, 10R, M, IOM) ? The Windstar probably comes close, but I understand it requires a lot of modifications before it’s competitive with a standard IOM.

I’ve toyed with some ideas around IOM-production, but it’s not likely that 2008 will see major progress (too much else to do…). If anyone has some news or ideas let me know! Now it looks like we will have MicroMagic sailing at both the Helsinki Boatshow (Feb 08) and the Helsinki Model Expo (Apr 08) - and I did sort of promise last year that I would turn up with a boat of my own in 2008…

Update: There’s an article in the latest Model Yachting magazine about Jon Elmaleh’s latest project the Twang IOM. It’s going to be mass produced and will hopefully be available in the summer of 2008. No word on Jon’s site yet…

A fast but unstable way of radio-sailing.

There’s a new version of WordPress available, so I’ve upgraded. Unlike brand new buggy closed-source commercial software, I’ve found no problems with 2.3 “Dexter”.

I’ve been browsing through a lot of scientific papers lately, and was struck by just how bad Nature’s doi resolving sometime is. Try this for example: http://dx.doi.org/10.1038/nature04268
You get to a page with the article title, the authors, and the reference. But no sign of a link to the abstract, the HTML article, or the pdf article!?

I’ve also found a discussion on various pdf/paper archiving services. I’d like something that integrates well with EndNote, any ideas?

I reluctantly sold a 20″ 1600×1200 Viewsonic with the desktop machine when I switched to my current T60 laptop (14″ 1400×1050) about a year ago. The screen is not the strongest point of the T60, and that feeling has just been reinforced by looking at some 22″ Samsungs at work. Now prices have plummeted again so I convinced myself that I need a 24″ 1920×1200 Samsung 245B!

I need a smart way of managing my desktop for normal mobile use (1400 pixels wide), working at home with this new toy (1920 wide), and giving talks/lecturing with video-projectors that are usually only 1024 wide. Any ideas?

Last day at model-expo, my first try at using google video!

First the new Futaba 2.4GHz radios. There are two wheel-model radios already on the market, and I was told two stick-radios (a 3-channel and a 6-channel model) will be in stores very shortly. Priced close to the Spektrum offerings at around 200 eur. Then to the pool for some scale-models. A fast electric racing boat after that, followed by some aerobatics, and some car-racing at the end.

(the noise from the fans was not as bad as it sounds in this video…)Then MicroMagic sailing! We had a lot of fun and a fair bit of spectators for each of our sailing shows, about 15-20 minutes every hour. You can see that the two fans we brought with us don’t cover all of the pool, and that the wind speed is quite fast near the fans and lighter downwind. More boats and more fans for next year!

When someone interested came to talk to us it was so easy just to point to the many MicroMagic vendors and say ‘there, that’s where you get it and it costs around 250eur with everything (boat, radio) included.’ This relates to what I wrote earlier, I believe the success of the micromagic largely depends on it being cheap and easily available.

So, for the IOM class to experience continued growth I think it would be a great help if a competitive boat would be mass-produced (in ABS or similar). I know Graham B in the UK and John E in the USA have had some plans… but nothing seems to have materialized yet. Newcomers to our sport don’t want to send 1000 or more euros overseas and then wait 3-6 months for a (hand made) boat, they want their new boat now, cheaply, and from the local hobby store.

Thanks to Jari for lending me his MiniDV camera.

Timo brought along his latest toy, a Micro Magic, to our annual radiosailing winter meeting. This thing really is small compared to a Marblehead or an IOM! It’s an all ‘plastic-fantastic’ ABS moulded boat, but you do have to glue the deck to the hull in this Racing version of the kit. The vitals are LOA=554 mm, Beam=178 mm, Weight=980 g, Height=980 mm.

The fin and rudder are made of ABS plastic, and the bulb is lead. There are different sized bits that can be inserted fore and aft of the fin in the finbox to adjust the position of the fin for different conditions.

An arm-winch controls both sails, the mainsheet on the left side of the boat and the jibsheet on the right. Timo is using a micro-servo for the rudder, but I understand standard sized ones are used too.

There’s one central hatch with a rubber seal, but I doubt it’s watertight enough to be used without tape on top.

The standard carbon mast is 5 mm in diameter, and comes with two sidestays, but Timo has made some more rigs using 6/4 mm carbon tube and intends to use these rigs without sidestays. A bit surprisingly rule-writers around the world have usually not put an upper limit to the number of rigs, so I understand some skippers have made up to 5 or 6 different rigs! (the smaller ones all fit within the biggest one)

In terms of number of boats/skippers the Micro Magic is a definite success with ca 1000 or more boats registered in both Germany and the Netherlands. It makes you think that the traditional international radio sailing classes (IOM, M, 10R, A) have somehow failed since they have not as far as I know attained similar popularity. Marketing wisdom tells us that this must be because of the five Ps: Product, Place, Price, Packaging, Promotion. (I’m leaving ‘Product’ last in my ramblings below, since I have the most doubts about this P)

Price: the Micro Magic wins hands down over an IOM or any other international radio sailing class. The whole MicroMagic kit with the tall rig, a basic two channel radio, and everything you need to go sailing costs about the same (300 EUR) as three suits of sails for an IOM. By comparison, I estimate a competitive IOM with three rigs and radio from a commercial builder costs about 2000 EUR. Home building a boat to the same standard and performance is not much cheaper.

So does price really matter? Die-hard radio sailors usually say no: travelling to events, staying in hotels, spending all that leisure time racing etc. constitutes a much bigger investment than the price of the boat. For someone who travels internationally every year and to all big events nationally it probably doesn’t matter if the boat costs 500 eur, 1000 eur or 2000 eur. But for the beginner it does matter! I see very few newcomers to competitive IOM racing in Finland - maybe that’s because of the high price tag? To really get into the class you need a competitive, watertight, and fully functional secondhand, or almost completely built new boat, and that’s going to cost you about 2000 eur…

Place: go to the local hobby store, hand them your credit card, and within 1-2 days you will be on the water sailing this boat. Depending on your country, getting an IOM is either a lot harder or just a bit harder. There are no industrial builders (The Robbe Windstar is not really a competitive IOM), so you can’t buy an IOM from a hobby store, and the salesperson in the shop is not likely to even know there exists such a thing as an IOM class. All manufacturers are small, most amateur hobbyists and a handful of professionals, and usually sell boats in kit-form to keep down the cost. In countries where there are no commercial builders the situation is even worse. The seasoned radio-sailors do know the international suppliers, some personally, but a newcomer is quite unlikely to send a big amount of money to an unknown builder in a foreign country (and wait the usual 4-12 weeks delivery time).

Packaging/Promotion: Probably about equal between an IOM and a MicroMagic. Promotion will largely depend on what class your local club sails I guess.

Product: Here’s where my doubts are. When moving from a Marblehead (4-5 kg weight, 1.3 m length) down to an IOM, the boat felt very nervous, unstable, and hard to sail in the beginning. An IOM is also definitely harder to trim for neutral balance. This was a move down in length from 1.3 m to 1 m, and in weight from about 4.5-5 kg to 4 kg. I haven’t sailed a MicroMagic yet, but we must be talking about a completely different behaviour at 55 cm overall length and < 1 kg displacement.

On the other hand, do skippers want a boat that sails and handles gracefully, like a full-scale boat, or are most skippers just looking for a level playing field where they can have fun racing the boats? If the latter is most important, then there must be a bright future for boats like the MicroMagic. In reality very few people have time to design and build their own boat, so I don’t think this argument against industrially produced boats really holds.

All of this seems to indicate smaller and industrially produced is better. But there must also be some kind of scale effect: If I show my IOM to someone on the street I’m sure most people would recognize it as more than a toy, capable of racing in widely varying conditions etc. Show the same people a MicroMagic and they will definitely think ‘toy’.

This is an interesting topic, so I’d love to hear some thougs from my readers:

1. I clearly haven’t done my homework well enough, so could someone fill me in on the numbers of boats in the big countries for the various ‘industrially’ made classes: MicroMagic, RC-Laser, Victoria, etc.
2. How does the MicroMagic sail in different conditions? preferably from people who have a solid background in Marblehead or IOM racing! How does it compare to an RC-Laser?
3. If you have some deep thoughts on how to make a radio sailing class really succeed I’m also interested.

The Finnish radio sailors publish an annual newsletter/magazine called Styyra. This year we have reports from Phocea Cup in France, Nordic Cup in Finland, Sweden, and Denmark + guides for building rigs and rigboxes. There’s also an update on the Noux project and a look at batteries and chargers.
Get it from the Styyra page. In Finnish/Swedish only…