* Posts by Steve Hosgood

73 posts • joined 11 Jun 2008


Asteroid miners hunt for platinum, leave all common sense in glovebox

Steve Hosgood

Re: Yet again - science story in bizarre mishmash of units

Hey - foxyshadis: no need to be rude! Obviously I can "grasp" that precious metals *may* be traded in troy ounces (though some markets operate in grams and kg). The point was supposed to be that in an article talking about mining asteroids, and mentioning tonnes of material, it's hard work dealing with prices given in an almost unrelated set of units like troy ounces. Even if those are the units that some markets use, price per tonne or price per kg are the obvious ones to quote in an article like this.

(*) Price per jub might be funnier, but until the International Convention of the Jub have standardised that unit of mass relative to the Planck Constant and Avogadro's number, it's all a bit moot!

Steve Hosgood

Yet again - science story in bizarre mishmash of units

"An increase in supply of as little as 250,000 ounces - seven metric tons - will drive the price down by a quarter."

Look - if you're writing an article about mining, please lay off with the "ounces" eh? Presumably you mean troy ounces anyway? While you're at it (and this may be pedantic), there is no such thing as a "metric ton". Well - maybe in the USA, but not anywhere else. It's called a "tonne" over here.

Later in the same article

"...asked if the markets are large enough to support the mining costs - yes, especially if we are able to bring back so much that the price goes from $1,500/ounce to $15/ounce."

Any chance we can have that in units that make sense please? Like "...price goes from $48000/kg to $480/kg" (assuming you meant troy ounces)?

Or, since it's a mining article that started with tonnes, maybe you ought to stick with that and have "...price goes from $48million/tonne to $480thousand/tonne"?

Is it too much to ask for a poll on extending the policy on metric-only articles to cover everything El. Reg covers (apart from beer)?

World's oldest digital computer successfully reboots

Steve Hosgood

ENIAC was an extremely odd architecture machine - never repeated! It was more like twenty or thirty simple arithmetic machines that could be physically wired so that the '"result" of any machine was the sum/difference/product of any two other machines. Almost like the boxes on a spreadsheet, except that you had to physically wire them together.

Like WITCH, the calculations were in decimal. However, I don't think ENIAC had the concept of "instructions" as such. It could iterate, but couldn't do the equivalent of branch out of a loop when a condition was met: i.e. it wasn't "Turing Complete".

Difficult to claim that ENIAC was a true computer therefore.

BOSS Bang boffins: DARK ENERGY spreading across the Universe

Steve Hosgood

Re: It's the best theory we have so far

Re: Franklin....

>>"You see, you *can* apply Newton's Theorem of Shells to globular clusters, and oh look, no need for dark matter."

>Unfortunately, doing that doesn't fit with OTHER observations, like the orbits of satellites around our planet, or the orbit of our planet around the sun.

Wrong way round, Franklin! Newtonian gravity fits in with all those classic observations you've listed - after all it was *derived* from them. Apparently Newtonian Gravity (with no help from "Dark Matter") explains the rotation of globular clusters too.

"Dark Matter" is deemed necessary to explain the rotation of disk-like galaxies. I call shenanigans on that and can show that Newtonian Gravity will do that job just fine too. All you've got to do is get your sums right!

Steve Hosgood

Re: It's the best theory we have so far

Re: Destroy All Monsters:

> 2) Dark Matter is pretty well established by observation and detailed computer simulation

Dark Matter has SO not been established by observation! That's a serious part of the problem. Even worse is the smoking gun that "Dark Matter" isn't needed to explain the rotation motion of globular clusters. You see, you *can* apply Newton's Theorem of Shells to globular clusters, and oh look, no need for dark matter.

The mistake is to use Theorem of Shells to summarise gravity behaviour in disks.

>> Any schoolboy with a knowledge of ordinary Newtonian gravity theory, a knowledge of computer programming and an ordinary PC can write a physics model and demonstrate the fact.

> I think therein lies the problem. You seem to assume that these simulations take short cuts of the "Computer Recreations" sort. These simulations run on large machine clusters for weeks on end and use code that is well-justified by theory, with tweaks well-justified by observation.

It doesn't matter what the simulations run on! If they've got their sums wrong, the results will be wrong. Large machine clusters for weeks on end or a simple PC for 10 min - it doesn't matter. Rubbish in, rubbish out.

It's your "tweaks well-justified by observation" that worries me....

Steve Hosgood

Re: It's the best theory we have so far

I don't know about the universe as a whole, but you don't need exotic matter, Modified Newtonian Dynamics (MOND) or "Scalar-tensor-vector gravity" to explain the observed rotation curves of galaxies. Any schoolboy with a knowledge of ordinary Newtonian gravity theory, a knowledge of computer programming and an ordinary PC can write a physics model and demonstrate the fact.

I realised this myself about a year ago and wrote a physics simulation of my own which panned out as I'd suspected. However, as I started to write up a paper on the subject (and did a better literature-search), I realised that I was by no means the first to spot the mistake: see http://arxiv.org/pdf/astro-ph/0309762.pdf for a paper by Nicholson dating from 2007. Nicholson's computer model deals with the thickness of galactic disks, mine assumed infinitesimal thickness but modelled the disk with a lot more point-masses than Nicholson did.

Regardless - we both get the same results as far as I can see. Huh: I was (at least) five years too late. No Nobel Prize for me :-(

What I can't understand is why the mainstream astrophysics community are still banging on about Dark Matter as an explanation for the "galactic rotation anomaly" when the real explanation is so simple and has been known for so long. They're not going to find any dark matter, y'know...... I strongly suspect that with Dark Matter not required to hold galaxies together, similar mistakes will be found to banish it from its other assumed purposes between galaxies.

You can't apply Newton's Theorem of Shells to disks! Isaac Newton himself knew that his theorem only applied to *spheres* of mass. Nicholson (mentioned above) wasn't even first to spot that error, but his paper is the first (that I've found) that actually reports results from computer modelling.

Snake-fondling blonde nude punts Polish coffins

Steve Hosgood

Re: Beautiful Polish women?

On the other hand, if you want to see what a real beautiful Polish woman can look like, check out Strictly Come Dancing's Ola Jordan. (Sadly, she's been booted out from this year's series already. )

Dark matter pioneer scoops Oz science prize

Steve Hosgood

Forget Dark Matter

Prof Freeman has indeed done some groundbreaking research into galactic structure, but his comments about the need for "Dark Matter" (from the *appendix* to his 1970 paper, not the main body) seem to have taken unfair centre-stage in the science of galactic dynamics.

It's all a mistake. You don't need exotic matter, Modified Newtonian Dynamics (MOND) or "Scalar-tensor-vector gravity" to explain the observed motion of galaxies. Any schoolboy with a knowledge of ordinary Newtonian gravity theory, a knowledge of computer programming and an ordinary PC can write a physics model and demonstrate the fact.

I realised this myself about a year ago and wrote a physics simulation of my own which panned out as I'd suspected. However, as I started to write up a paper on the subject (and did a better literature-search), I realised that I was by no means the first to spot the mistake: see http://arxiv.org/pdf/astro-ph/0309762.pdf for a paper by Nicholson dating from 2007. Nicholson's computer model deals with the thickness of galactic disks, mine assumed infinitesimal thickness but modelled the disk with a lot more point-masses than Nicholson did.

Regardless - we both get the same results as far as I can see. Huh: I was (at least) five years too late. No Nobel Prize for me :-(

What I can't understand is why the mainstream astrophysics community are still banging on about Dark Matter when the real explanation is so simple and has been known for so long. They're not going to find any, y'know......

You can't apply Newton's Theorem of Shells to disks! Isaac Newton himself knew that his theorem only applied to *spheres* of mass. Nicholson (mentioned above) wasn't even first to spot that error, but his paper is the first (that I've found) that actually reports results from computer modelling.

SpaceX Dragon podule back from ISS, successful Pacific splashdown

Steve Hosgood

Re: Remember that readers' poll?

Hot d*mn! "AC" is right, the small print of the poll does indicate Special Projects only.

That's a bummer. May I propose El. Reg consider another poll, with the goal of extending that policy to all articles? I'm heartily fed up with having to wade through articles peppered with units translated into all sorts of other units when simple straightforward S.I. (*) would have done the job the first time.

It must be a right pain for El. Reg hacks to have to do all these translations in the first place. And some of them get to be just plain wrong too....

(*) Notice that round here, the "Olympic Sized Swimming Pool" *is* an S.I. measurement, being 50m x 25m x 2m - i.e. 2500m³ or 2500 tonnes of water. Not sure about Wales....

Steve Hosgood

Remember that readers' poll?

Article should be saying:

"The reusable cargoship dropped into the ocean yesterday evening around 400 km off the coast of Mexico after resupplying the ISS and its crew. The Dragon was ferried to a port near Los Angeles where it will be prepped for its return to SpaceX's test facility in Texas.

Some of the cargo brought back by the capsule is due to be returned to NASA in the next couple of days, including research samples from the station's microgravity environment. The ship delivered 400 kg of gear to the ISS, including scientific research and crew supplies. It returned with nearly twice that mass of stuff."

There - fixed that for you! Notice the "weight" -> "mass" fix in the final line too.

Astroboffins out FREAK 'BI' GALAXY

Steve Hosgood

Re: Excellent unit conversion maths

Indeed - if El.Reg were paying attention to their own poll results, this wouldn't have happened. Having said that, when talking about galactic diameters and intergalactic distances then even km isn't really appropriate any more - lightyears or parsecs are how the astronomers would measure it (and according to Wikipedia, parsecs is preferred).

The parsec is at least a "non-S.I. unit accepted for use with S.I." just as hours and minutes are. So it would seem that use of parsecs in El.Reg stories would at least generally comply with the outcome of the "units of measurement" poll.

GIANT EYEBALL PANIC ends: Oceanic peeper identified

Steve Hosgood

Or, according to the El. Reg readership poll....

"Xiphias gladius seeks out prey species up to 600m down".

Actually, maybe even this revised version needs revision. Can you have "up to X down" in the same sentence? How about:

"Xiphias gladius seeks out prey species down to 600m".

There - fixed that for you!

Skydiver Baumgartner in 128,000ft plunge from brink of space

Steve Hosgood

Re: Not quite there yet

Not sure about standards soviets, but certainly El. Reg's journos can't be reading the results of their own poll from last week which was resoundingly in favour of stories being in S.I only with the possible exception of pints for beer and ft. for aircraft altitude.

I don't think this story would have counted as having anything to do with "aircraft altitude" in the normal sense of the phrase, and it's certainly not about beer. So the readers' poll seem to have requested it be reported in metric only then.

Fine by me - much easier to read that way.

Metric versus imperial: Reg readers weigh in

Steve Hosgood

Metric is not necessarily the same as decimal

One of the poll options was listed as "SI Units only, under punishment of a lick of the cat o' nine tails (imperial), or ten tails (metric)".

Whilst amusing, it is worth noting (because some of the posters here evidently "don't get it") that though the major multiples of the metric system are powers of ten, there's nothing non-metric about 24 hour days, 60 minute hours, eggs by the dozen or any other non-decimal multiples.

The S.I. unit for time is the second. Speeds are therefore in m/s fundamentally, but in practice all over the world, road speeds and speed limits are always given in km/h. Nothing wrong with that, despite the hour having a non power-of-ten number of seconds in it.

The point is that it's the standard everywhere in the world (except for the USA and here). By not using that standard in daily life, we're crippling our country's ability to compete.

Curiosity finds . . . wait for it . . . a ROCK on MARS!

Steve Hosgood

"Curiosity will now rumble forward another 100 yards to the east..."

Nooooooo! Whazza matter with you people? That should have been "Curiosity will now rumble forward the length of about ten London buses to the east..."

or, following the comments on the recent "units" debate:

"Curiosity will now rumble forward another 90 m to the east..."

It’s official: Google shrinks the world!

Steve Hosgood

Re: El. Reg can't even get El. Reg units right!

A quick check on the El. Reg standards converter seems to show that the official "London bus" chosen for the job was the classic Routemaster at 9.2m. Whatever, the new Google shrunken Earth radius is only ⅔ of that.

Steve Hosgood

El. Reg can't even get El. Reg units right!

The old classic Routemaster London bus was about 9m long, the current "BorisBus" Routemasters are more like 11m long. So it's probably fair to say that the El. Reg "a London bus" is 10m ±1m.

If Google's evil criminal masterminds have indeed shrunk the world to 6.365m radius, then that's a good bit smaller than "a London bus".

ISS crew fling out arm, grab SpaceX Dragon capsule

Steve Hosgood

Re: Units

Except that SpaceX works in S.I. units. So (apparently) does NASA these days - see the reports coming off the current Mars rover project. That all seems to be in S.I. too. It's NASA's traditional aerospace partners (Boeing, Northropp, McDonell Douglas etc) who appear to be the U.S.C Luddities.

SpaceX is *not* one of those.

Register SPB hacks mull chopping off feet

Steve Hosgood

Re: Go For It

My Garmin does that too. That's why I run the thing in metric. "In 300 metres, turn left" - yeah, that's at least comprehensible even if the matching roadsign says 330yds.

But of course there almost never is a matching roadsign, so I just go with metres and ignore the Department of Transport's insistence on hanging on to useless old units on their signs.

Steve Hosgood

Neither natural nor God-given

This *is* science! The inflation of the early 1970s was nothing to do with Britain switching to decimal currency - that's why everyone else suffered it too. It was mostly caused by the "Oil Crisis".

£sd was a hideous mess consisting of a mutated form of a heathen currency forced upon the oppressed masses by the iron heel of the Roman Empire 2000 years earlier. That it took us all that time to decide to get rid of it should be a matter of national shame.

LSD on the other hand was much more fun......

Steve Hosgood

How many times do we hear this tabloid rubbish being churned out?

It's not French - how many times does it have to be pointed out? Only the Daily Mail thinks it was French, or forced on Europe by Napoleon or various other crap.

Metric as a recognisable concept was first promoted the Royal Society in London in the 1680s. Over a hundred years later French king Louis XVI ruled that it should become the official system of France to replace the ridiculous hodge-podge of systems being used in his kingdom at the time (every town had its own variant).

Steve Hosgood

Metric all the way please

As many others have commented - S.I makes far more sense for a tech-orientated website such as this. Don't bother with silly exceptions either like pints of beer or miles.

And certainly not stones for body weight - I mean, really, is anyone who's actually keeping note of their weight still doing that in stones? Weighing machines in the gyms and leisure centres of the UK have been in kilos for years, likewise the ones in hospitals and doctors' surgeries.

I agree with the poster above who pointed out that we ought to switch to having the line on our beer glasses redrawn at 500mL, but to keep the size of the glassware the same. A proper head on our real ale without being short-measured would be a pleasure. I hear that certain pub chains teach their staff how to game the beer "top up" law so as to try and serve deliberate short measures wherever possible (to the pub chain's profit of course).

But - hey - this is getting off topic since it's not common for El. Reg stories to be about beer anyway.

So I chuck my vote in with the "just do it in S.I metric units" brigade.

Oh, 53 yrs old, 1.72 m tall, 66 kg in case you were wondering.

Whopping supersonic-car rocket rattles idyllic Cornwall

Steve Hosgood

Re: pandering

Re 'FatGerman' above: The units are *utterly* important in an article, and there should only be one set given (S.I in this country). Otherwise, people (our kids even) end up inadvertently memorising something like the melting point of steel (say), only to discover later in life that they'd accidentally memorised the value in Fahrenheit due to some dumb-arse journalist who thought that "the units didn't matter".

And, non sequeteur though it was, no we wouldn't have ourselves or anyone else "going into pubs and asking for a 0.56826125 litre of beer". Since when (outside a university chemistry lab) would you ever expect someone to be able to measure any fluid to the nearest 10nL? What we might expect is to order a nice sensible 500mL, expecting to be served with any random value between about 490 and 510mL (i.e plus or minus a spoonfull or two).

Steve Hosgood

Re: pandering

Except that we live in Britain which has been an officially metric country since the mid 1990s and has in fact been all-metric for science and engineering since the 1970s or early 1980s.

But most of all, assuming the idea is to encourage youngsters into studying STEM subjects, maybe journalists would wake up to the 21st century (or even the 20th) and write articles in the same units as those schoolchildren use - metric ones.

I can at least congratulate El Reg for making less of a Luddite-centric, pro-imperial-units cockup of a story than the BBC just did. (http://www.bbc.co.uk/news/science-environment-19818009)

And stuff France. Apart from the fact that it was their last pre-revolution king who decided that they would become the first nation actually to use the already 100 year old metric system (invented in Britain), neither the French (nor the E.U) have any claim to it.

If you, 'skirmish' don't like it, go like in the USA where they use a system that is not based on mathematics, nor on the number of fingers humans happen to have, nor on any other rational principle.

Dawn probe slips Vesta's grip, heads for icy dwarf planet

Steve Hosgood

Re: Ceres: "our solar system's only dwarf planet"

Get the quote right, and all will be clear: "Ceres, our *inner* solar system's only dwarf planet and its largest asteroid".

The clue is in the word "inner" :-)

LOHAN to brew thermite for hot ignition action

Steve Hosgood

Stratosphere cartwheel worry

I'm concerned about the comment from a poster in the previous thread who pointed out that even if you master the ignition problem (which you will), then you're got the problem that the rocket will blast off into air so rarified that the fins at the rear will offer no useful stability.

This will result in the rocket cartwheeling uncontrollably and going almost nowhere. There's a reason that Von Braun's A4 (aka V2) rockets had graphite vanes in the path of the exhaust, coupled to gyroscopes in the nosecone. Later, more powerful designs achieve the same control effects by gimballing the entire engines.

LOHAN is sufficiently low-power that graphite vanes would work just fine, but adding all the actuators and gyros will make the whole endeavour far more complex than it is at present. And crank up the costs of course.

But will it even work without such measures?

LOHAN fizzles forlornly in REHAB

Steve Hosgood
Thumb Up

Re: Odd data conflict on your video...

That would tie up fairly well. Thank you for that.

Steve Hosgood

Odd data conflict on your video...

I like the video! Very cool.

The commentator comments that your motor is a "100N" motor which I thought might mean that it can generate 100 Newtons of thrust. If so, it would be able to lift 10 kg at ground level, which I think looks a bit optimistic...

Your kitchen scales bears this scepticism out showing a reading of 1797 grams when the motor lights (notice though that for most of the burn, the reading is more like 1400 g). Please note that thrust shouldn't be measured in grams as claimed at the end of the video. Keep thrusts in Newtons please, or you'll likely be headed for an accident.

The scales are actually measuring force, but "helpfully" converting this to equivalent mass assuming normal earth gravity of 9.81m/s². You ought to convert back. If you get a reading of 1797 g (which is 1.797 kg), then that's 1.797 * 9.81 which is a thrust of about 17.6 N

However, 1.4 * 9.81 - i.e. 13.7 N would be more representative of most of the burn time.

[ Additionally, since the motor was sitting on the scales and firing upwards (thrusting downwards) you needed to subtract the dead weight of the motor from the indicated scales-readings before multiplying by 9.81 to get the generated thrust. ]

This brings me back to the original comment. Why is the motor apparently claiming 100 N thrust. It's not even generating a sixth of that. Is the "100N" just an arbitrary part of the model number, nothing to do with the thrust?? Or what?

Steve Hosgood

Re: A suggestion

Ah - you think you want maintain circa 1 bar pressure inside the motor do you? I was assuming (see post further up) that the pressure plug was just to cause pressure to rise and stop gas being lost as just the first couple of grams of fuel ignited.

If you rely on holding 1 bar pressure in the motor, it might work in REHAB but would be hard to maintain those conditions under a helium balloon that might take an hour to reach launch height.

Steve Hosgood

Re: Plug

Probably all true from Vladimir above, I'm no expert on this but bear in mind that when you fit the plug you'll be doing so under normal atmospheric pressure (close to 1 bar) but you'll be evacuating the chamber to around 20 mbar pretty soon afterwards. You'll want the plug to be loose enough or porous enough that the ambient pressure air inside the motor can be extracted along with the surrounding air.

There is also the question of how the copperhead igniter works... does it try to eject a small amount of burning gas in the general direction of the motor's fuel core? If so, it might be that the burning hot gas dissipates too fast in the 20 mbar environment (and in doing so, cools down too fast).

I'd think that if you laid an elongated horseshoe of manganin resistance wire physically inside the hole that runs through the rocket fuel core, then you could energise that. It would heat up to red or orange heat if you got the sums right, and being in contact with the rocket fuel *ought* to set it off.

LOHAN finally checks into REHAB

Steve Hosgood


I suspect the shiny lump of perspex will land in France about 45 minutes after the test. And it won't be shiny. It will be a lump - but blackened and twisted. The French government will probably call the Spanish ambassador in "for a chat" and he'll summon the conquistadores to head into the hills, round up the El Reg culprits and "deport" them from the country forthwith!

That's "deport" as in minus their heads. The heads will be left on pikes at the roadside to discourage anyone else trying such a thing!

:-) (In case you hadn't guessed)

Steve Hosgood

Lessons from history

"In tests, we were able to draw an indicated vacuum of 27.5 inches – equivalent to a pressure of 60mmHg, or an altitude of 60,000ft (18,290m)."

Then later....

"With the pump fired up and connected to the REHAB chamber, we managed to draw a vacuum of 20mbar – equivalent to around 76,500ft, or 23,300m - pretty well spot on our target of 15mmHg."

Aaaagh! One minute it's vacuum in "inches", then it's pressure in "mmHg" then it's pressure in mbar. Several times the units appear compared on against the other in the same sentence!

It's a recipe for disaster. Please just work in one set of units to give the project a chance of working? People with bigger pockets than yours (like NASA) have trashed billions of dollars of equipment due to conversion errors. Learn from history.

Looks like the gauge on the latest equipment you've been given works in mbar. Get all the gauges working in mbar, and cross-calibrate them. Think of your goal target-pressures in mbar, and please never mention "inches" or "mmHg" ever again. Give LOHAN a chance to work at least.

Steve Hosgood

50 Megabar? Typo alert!

"AVE head honcho John Licence got in touch to offer us the loan of a shiny and expensive suppressed zero gauge, designed to kick in below 50Mbar and with an accuracy of around 1Mbar."

Methinks that's 50mbar and 1mbar respectively, guys. You wouldn't experience 50Mbar unless you went a long way into Jupiter's atmosphere!

Steve Hosgood

Re: Is there a daft question?

Rocket fuel carries its own oxygen. That's how it is that you can fire rockets in space and they still work! If you think about it for a moment, the amount of ambient oxygen even at a "mere" 25km altitude will be minimal.

Leap second bug cripples Linux servers at airlines, Reddit, LinkedIn

Steve Hosgood

Leap seconds: not a one-off unique event

How did this ever happen anyway? There's a leap second about once every 18 months IIRC, so it's not like Y2K where no-one had ever experienced the event before it happened!

NASA's Curiosity rover will try risky landing near Mount Sharp

Steve Hosgood

Re: 0 out of 10 for arithmetic

asdf writes: "Us oddball Americans always have to do it wrong eh?"

I never said anything about "wrong", but even you "oddball Americans" have to agree that your press seem to habitually report most things in imperial measures only. Even for those things which you'd think everyone would WANT to have in metric measures, like (say) the results of long-jump, triple-jump, high-jump, pole vault (etc) in athletics meetings. Your own athletes must struggle with seeing the results for those events reported in feet and inches, considering that at any international athletics meeting those same things are going to be measured in metres.

Yet it seems that the "oddball American" press do refer to athletics running distances in metres. So Usain Bolt's 9.69sec running record is still in the "100m sprint", not the "109yards 1ft 1 inch dash". Strange.

I note with enthusiasm though that the "oddball American" space agency NASA are evidently doing their science in metric even if the "oddball Americans" press can't cope.

Steve Hosgood

0 out of 10 for arithmetic

El. Reg. claims: "The previous landing target zone for the MSL was around 12 miles (19km) wide and 16 miles (26km) long. The new narrower zone is just four miles wide (6.4km) and 12 miles (19km) long."

If you go look at NASA's (original) version of this you get: "The larger ellipse, 12.4 miles (20 kilometers) by 15.5 miles (25 kilometers) was already smaller than the landing target area for any previous Mars mission, due to this mission's techniques for improved landing precision. Continuing analysis after the Nov. 26, 2011, launch resulted in confidence in landing within an even smaller area, about 12 miles by 4 miles (20 by 7 kilometers)."

Looks like El. Reg. got the story from someone who'd decided that the imperial measurements must have been the "real" ones, then rounded them to the nearest integer, THEN somehow the rounded-off imperial measures got converted back to metric with the assumption that they were still accurate.

What an utter mess.

If you look around NASA's entire 'Curiosity' site, all the scales on maps, onscreen graphics and other stuff is in metric measures only - they've just provided an imperial version in the blurb on the press release page presumably for the benefit of the U.S. press and U.S public who are apparently incapable of dealing with anything else.

Can't we just have the metric measures on their own over here, eh?

Code glitch floored Reg reader altimeter

Steve Hosgood

Please stop beating up Neil Barnes!

Hey folks. Neil Barnes generously donated his altimeter to the project to help further progress. Not nice to slap him around just because the instrument got taken beyond its design goals.

Coding standards like insisting on "long" or "short" in preference to "int" don't guarantee anything (I presume we're talking about C here). Read the C language spec - a C compiler is within its rights to have "short" mean 8 bits, and "long" be 16 bits. Especially for a microcontroller C compiler.

I would suggest to you Neil that if you have to rewrite the mbar->altitude calculation that you do it in metres this time round. You'll have more headroom that way, but you'll still need to work unsigned or you'll be limited to 32.768km. The world height record for a helium balloon is apparently 53km, still well within the range of a 16-bit unsigned.

I can understand why you did altitude in feet for the original application of the instrument, but that was for GA use in Europe for a glider. This is for an unmanned balloon rocketry experiment. No need for mediaeval stuff here.

Steve Hosgood

Re: @Robert E A Harvey

I believe the Zeppelins had such a thing. If the ship rose above 5000m (IIRC) spring-loaded valves on each of the gas-bags in the ship would start venting hydrogen.

Such an idea might make good sense for the LOHAN project as surely being able to fire the rocket from a stable balloon-supported platform would be good? However, it is one more thing to go wrong....

Steve Hosgood

Re: quick - call him back

True about the rate-of-climb approaching zero, but from what I've seen of helium balloon stratospheric rubber chicken exploits, the balloon usually bursts before it reaches its theoretical maximum height (where rate-of-climb would actually be zero).

At the point the balloon bursts, the rate of climb becomes -9.81m/s²: probably sub-optimal conditions for firing the rocket! I guess the plan is for LOHAN's trigger to go off well below this height.

Steve Hosgood

These are not the bugs you're looking for....

Dear Reg: You claim "What happens after that is up to the software. This time RTFM could be misleading; the MS5534 datasheet says 'All calculations can be performed with signed 16-Bit variables.' Maybe so if you deal only in metres."

Having just taken a look at the datasheet, I agree - it's a typo. They should have said "...can be performed with unsigned 16-bit variables." They contradict their own statement two line further down the page with "This division can be performed by Bit-wise shifting (divisors are to the power of 2). It is ensured that the results of these divisions are less than 65536 (16-Bit)."

However, this isn't the source of your bug. The "calculations" being mentioned only serve to generate the local air pressure (in mbar). Your software problem is probably in the next stage where you convert from mbar to altitude.

And as you said yourselves - if you'd worked in metres as you should be doing (!) then at least you'd have delayed seeing the problem until an altitude of about 32.768km which is seriously high - about the same height achieved when launching rubber chickens attached to helium balloons.

Away with this "feet" and "inches of mercury" mediaeval fixation, folks. The altimeter chip gives you mbar not in.Hg. Luckily with your "convert to feet" bug, you didn't throw a couple of million quid's worth of rocket into the ocean (or into Mars as NASA did last time they went mediaeval).

Bloke with spanners attacks LOHAN's dodgy plumbing

Steve Hosgood

Looming disaster ... take avoiding action now!

Is there any vague chance that the El Reg Space Agency can learn from the past and not repeat NASA's mistake of using a useless rag-bag of mediaeval measuring systems for a science project? I mean, you're continually converting from inches of mercury to pounds per square inch to equivalents in feet of altitude....

You're just BEGGING for trouble. Use sensible measurements from the get-go and be done with it please! Altitudes in metres, pressure in bar(*) (well millibar mostly in this case). Many of the suggestions from readers are coming in using those units - if you keep converting to and from your antiquated ones, sooner or later you'll have a cockup on your hands...

..which, considering the name of the project is probably appropriate! Arf, arf.

I'll get me coat.....

(*) Pressure measurements should be in Pa (Pascals) if you want to be *proper* rocket scientists, but 'bar' is easier to visualise (being pretty close to normal atmospheric pressure).

BTW: 1 bar = 100000 Pa, a.k.a 0.1 MPa.

Pints under attack as Lord Howe demands metric-only UK

Steve Hosgood

"Fail" indeed, Arachnoid.

Industry changed to metric years ago. Doing so *earned* us billions of pounds, since no-one in the world was going to buy our stuff it was all in wacky mediaeval measurements.

Double "Fail" in fact:

What's this "European metric unit" rubbish then? How did Europe magically force Japan, Russia, Australia, New Zealand, China, India, Pakistan, Iran, Iraq, Saudia Arabia, Egypt, all of Africa, all of south America, Canada, and Switzerland to use "their" metric system then?

Answer - because it's nothing to do with bloody Europe. Well, nothing to do with the bloody E.U. anyway. It was designed by philosophers from everywhere during the 1700s to be a better replacement for all the random different systems in use in those days. And if anything, it was kicked off by the Royal Society of London. So it's "ours" :-)

Britain has been "an officially metric country" since the mid 1990s. Trouble is, as Lord Howe says, there are some pointless anomalies that are an embarrassment to the image of the country. Like the road signs. Like the fact that you're not allowed to buy a litre of beer in an Austrian themed bar in Britain.

Ireland saw sense and fixed its roadsigns 15 years ago. Their kids are now just that bit better than British kids at estimating distances in a measuring system that anyone else uses. We can do that too. In a recession, every little you can do to improve your competitiveness is important.

Steve Hosgood

Standard gauge (was Re: Try buying Pipe)

Standard gauge is actually 4' 8½" ? (4 minutes, 8½ seconds of arc??)

Only in the U.S.A.

Everywhere else in the world it's 1435mm (though 4ft 8½in is well within the tolerance allowed).

Steve Hosgood

Re: Consistency

Just use litres per 100km. It's by far the best way because (assuming you know how far your journey will be) then you can easily work out (in your head) how much fuel to buy.

It's just the same as making any other change to your thinking. A bit of a misery for a couple of months and then you never think the old way again. My car drinks 8.5L per 100km. If I want to drive to London (about 350km) I'll need 3.5 times 8.5 litres of fuel. Call it 4 times 9 to make it easier on the brain and to have a bit left for a safety margin - that'll be 36 litres then.

Simples! <<eek>>

I run my GPS in metric because it's a Garmin, and when run in "Statute" units, it announces everything in miles and feet! I'll have the kilometres please, that makes it possible the get used to journey distances in km (despite what the archaic roadsigns claim) and which I need to know so as to estimate how much fuel to buy (see above).

Steve Hosgood

It's amazing...

Amazing to find *any* readers of El Reg. who actually want to keep some outmoded trash (like the vestiges of the imperial system) when there is NO WAY any of them would be seen dead with an outmoded trash mobile phone the size of a brick with an aerial sticking out of the top!

El. Reg. readers are famed for being right on the ball regarding where to get the utterly utterly latest new shiny Android XYZ phone running IceCream TripleSandwichWithExtraMayo (and all the latest apps) at a good price. Why would any of them admit to supporting a creaking weights and measures system dumped on us nearly a thousand years ago by Norman French invaders?

No - come on guys. We want the LATEST toys. Imperial measures are the equivalent of being the size of a brick with an aerial sticking out the top. Or maybe the equivalent of MSDOS running on a 12MHz 286.

And about as useful.

Steve Hosgood

Re: Keep it just as it is

It doesn't keep our minds more agile - it just means that most British people can't use the system we need if we're to be meaningful in the world any more.

Inches don't work better than centimetres (or millimetres). That's just you.

People are not weighed in stones - go to the gym for a workout, you'll weigh yourself or be weighed in kg. Go to the doctor's - you'll be weighed in kg. And if you're not familiar with your weight in kg, and your doctor makes a mistake, how are you to point out "hang on, I'm 72kg, not 82kg". Such a mistake could kill you.

You're obviously trolling with the fathoms bit, I'll pass on that!

But no - it's not about "just using SI for science". We all need to use it for everything. That way, when we use it for something serious and make a mistake, we'll notice that the answer is absurd *before* building the doomed bridge (or whatever we were doing).

Steve Hosgood

The reason....

The reason for anyone wanting to finish off the (mostly done) job of getting rid of the last vestiges of the old measurement system is that for Britain to be Great again, we need to be designing, engineering and making stuff to trade with the rest of the world. For that we need a workforce inherently able to work in the same units as our customers will want. Which is metric.

( Forget the anomaly that the U.S. still works in U.S.C; as a trading partner they are well down the list in terms of volume of trade. )

The thing is that while our street signs insist on forcing miles and MPH down our throats, most British people struggle to reckon longer distances in those units that we need for our prosperity. Even those units we need for our own purposes 99% of the time.

Changing the roadsigns need not be expensive. It's not as if you actually have to *replace* the existing signs. Councils use sticky retro-reflective plastic patches all the time to correct spelling mistakes and other minor stuff on signs. All you have to do is change the rules to require new signs to be put up with km distances, and permit old miles signs to be patched to km as part of a rolling refurbishment program. You could also expect central govt. to pony up a bit of cash to allow councils to train up a few extra blokes with "working at height" qualifications just to go and patch the ludicrous signs claiming "junction in XXXm" where "m" means "miles". Which crack-smoking bureaucrat ever allowed that abuse of international conventions I have no idea.

Yes - it will be inconvenient for us drivers for about a month. Just as the conversion from £sd to £p was an inconvenience for a month or two in 1971. I was there. I remember it (just about). But now we reap the rewards of that month or two of inconvenience back then. Same with the roadsigns.

And our children will thank us for it.

Steve Hosgood

Lord Howe is right. It's a mess, and I'm surprised so many El Reg readers are in favour of carrying on with the mess.

Notice that your "pint down the local" isn't a pint unless you drink what that pub has on draught. If you like Guinness but they don't have it on draught, you'll be served with a 500ml tin tipped into a pint glass.

Same with Grolsch, and any other favourite of your that isn't on tap.

It's been like that for years, and I assume no-one's noticed or cared. Certainly you'd still *call* it "going for a pint" even if (under this strange arrangement) you've been drinking half-litres all along.....


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