Wikipedia:Reference desk/Archives/Science/2015 September 7

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September 7

Noise of trucks

If an average modern car and an average modern truck have their engines idling (and are doing nothing else), the truck is likely to make a lot more noise. Why? -- Hoary (talk) 05:47, 7 September 2015 (UTC)

The truck often has a bigger (and thus noisier) engine; it often has a diesel (and thus noisier) engine; quietness may be less of a design emphasis for a truck than for a passenger car. I assume you are referring to a large goods truck rather than a noncommercial, more car-like pickup truck. Short Brigade Harvester Boris (talk) 05:55, 7 September 2015 (UTC)

All true. I'm thinking neither of car-like pickup trucks/vans, or of huge trucks; rather, of circa 2-tonne trucks: very definitely trucks, but small ones. Diesel would be a factor. But silencers (mufflers) and choice of fuel aside, are there fairly straightforward ways of making internal combustion quieter, and hasn't there been pressure to apply them to truck design as well? -- Hoary (talk) 12:17, 7 September 2015 (UTC)

Motors of most any kind are inherently noisy. Some degree of that noise is regulated, hence the use of mufflers. And the interiors of cars are often packed with noise-deadening material so the occupants won't be overwhelmed by the engine's roar. As for other regulations, that would be driven by a preponderance of public demand, if any. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:56, 7 September 2015 (UTC)

I don't normally pay much attention to cars, but I think that most still have engines in the front, and that the engine has little that obviously (to an ignoramus) muffles its sound either above it or below it. Diesel-engined cars are unusual where I am (Japan), but memory tells me that their engines too are much quieter than are truck engines. I'd guess that part of the difference is that (quite aside from exhaust silencers and other sound insulation outside the engines themselves), car engines are designed to be quiet and truck engines are not; but I've no idea how this is done. (As for the sheer size [displacement] of engines, I presume that a lot of the trucks I'm thinking of have engines that are no bigger than those in some, much quieter, "luxury" sedans.) -- Hoary (talk) 22:39, 7 September 2015 (UTC)

Diesel engines can also be noisy due to Compression-release engine braking (Jake brakes). StuRat (talk) 14:40, 7 September 2015 (UTC)

Less than likely when they're idling, as the OP asked.--Phil Holmes (talk) 17:14, 7 September 2015 (UTC)

Yes, That is not quite right. It is the higher pressure rise compared to the petrol engine that results in more noise. Methane compression -ignition-engines (which were used to generate electric power) had an even higher compression ratio and made a lot more noise. The metal of the cylinder head flexes at these pressures like a loud speaker cone and produces a frequency which matches the multi- cylinder RPM compression stroke.--Aspro (talk) 20:14, 7 September 2015 (UTC)

That's interesting. Although I do know that diesel-engined cars are very unusual where I am (Japan), I don't know what percentage of trucks here run on diesel. Lazily, I hadn't even thought much about this. (There's a fair amount of public worries here about the carcinogenic properties of diesel exhaust, so I'd guess that the use of diesel is decreasing.) -- Hoary (talk) 22:39, 7 September 2015 (UTC)

If you ever look at the ads, the manufacturers seem to view noise as one of their most desirable 'features'. It's not merely their way of trying to say "this is a big engine"; it's more than that. They run ads where people all around are supposed to be running to the window to see who the big shot is who proves his superiority by shaking them out of their beds with his powerful engine. I think the thought process is "I'm the big noise, I'm better than you", not anything technological at all. It could be stopped by regulation, of course, but regulators at least in the U.S. seem absolutely determined to say that noise is purely a local issue, and since trucks aren't built locally, that means you're SOL for imposing any standards unless you want to have the truck-free community in your region. The only regulations they can get behind (virtually instantly) is to make vehicles noisier with back up beepers, noise generators on cars that might be too quiet for someone blind to hear, whatever excuse... Wnt (talk) 18:29, 7 September 2015 (UTC)

What you say depresses me but doesn't surprise me. -- Hoary (talk) 22:39, 7 September 2015 (UTC)

Don't be depressed it is mostly misinformed nonsense. Vehicle noise is regulated in the USA, EU, japan, Australia, and indeed almost every first world country, and many others. Here's medium and heavy truck noise regs for the USA http://nepis.epa.gov/Exe/ZyNET.exe/9100NQJQ.txt?ZyActionD=ZyDocument&Client=EPA&Index=1976%20Thru%201980&Docs=&Query=&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=&QFieldYear=&QFieldMonth=&QFieldDay=&UseQField=&IntQFieldOp=0&ExtQFieldOp=0&XmlQuery=&File=D%3A%5CZYFILES%5CINDEX%20DATA%5C76THRU80%5CTXT%5C00000017%5C9100NQJQ.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=1&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=p%7Cf&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=3 Greglocock (talk) 07:52, 8 September 2015 (UTC)

• Or, more tersely, http://nepis.epa.gov/Exe/ZyNET.exe/9100NQJQ.txt?ZyActionD=ZyDocument&Client=EPA&Index=1976%20Thru%201980&File=D%3A\ZYFILES\INDEX%20DATA\76THRU80\TXT\00000017\9100NQJQ.txt&User=ANONYMOUS&Password=anonymous&ZyEntry=3 —Tamfang (talk) 21:43, 8 September 2015 (UTC)

@Hoary, Greglocock, and Tamfang: The Noise Control Act of 1972, as described at that article, was defunded in 1981, leaving the EPA doing little about it but writing reports and advising local governments. Wnt (talk) 21:39, 11 September 2015 (UTC)

What do orbital space tourists need to learn/train?

What do orbital space tourists need to learn/train?--Jubilujj 2015 (talk) 18:40, 7 September 2015 (UTC)

Basically it is astronaut trainings but they don't need to learn how to perform a specialization (ie. Work in zero G). Space suits, pressure chambers and rocket simulators: Photos reveal singer Sarah Brightman's gruelling training regime to become an astronaut. From what I can gather is, that once one can use the bathroom and be able to say in Russian OK, I finished and it vacant again -your halfway there.--Aspro (talk) 19:34, 7 September 2015 (UTC)

Astronaut training has it explained, at least for professional astronauts. Standards for space tourists are not well-defined according to the same article. They certainly will train them enough for being independent and not being a risk for the mission or themselves, but I suppose they rather prefer that space tourists don't try to do anything by their own.

Anyway, if things go wrong like in an Apollo 13 kind of mission, I'd prefer to be one in a team of three carefully selected and trained professional astronauts, not with an opera singer (or businesswoman, Microsoft software developer, Internet security entrepreneur or what you got). --Yppieyei (talk) 12:32, 8 September 2015 (UTC)

Microsoft software developer? Uhm, can imagine what you men: Huston. We have problem, all computes have crashed. Our space tourist is insisting we have to update to Windows 10... ! Please advise on how Ellen Ripley managed to eject her alien into outer-space – over.— — Beep. --Aspro (talk) 19:25, 8 September 2015 (UTC)

What is a Deodora pine?

A source I used for Fulton-Mock-Blackmer House which, as far as I know, is not online, claimed there were Deodora pines in the yard of the house (and also said "(cedars)"). An earlier source called them cedar trees but when I look at the house I can see several different versions of what might be called a cedar tree. So I didn't know what to do other than link to the disambiguation page. Someone edited Sidney Blackmer, which I split the content from today, to change the Wlink to cedrus. Which does look sort of like a pine.— Vchimpanzee • talk • contributions • 19:27, 7 September 2015 (UTC)

Have a look at Cedrus_deodara, AKA deodar(a) cedar/pine. It is not a Pinus, but Cedrus is in the Pinaceae family, so when considering common names, note that "cedar" and "pine" and even "juniper" can get a bit fouled up with respect to the actual scientific classification of species (though these common names are fairly likely to fall into the order Pinales). Also Thuja sometimes gets tangled up in this, leaving us with e.g. the Western Red Cedar that is not in the Cedrus genus.

Anyway, if you have a print source that says "Deodara Pine" and also "Deodara Cedar" or seems to mix up the names a bit, tree is very likely C. deodara. SemanticMantis (talk) 19:45, 7 September 2015 (UTC)

The spelling is "deodora" but that could be a mistake. Thanks.— Vchimpanzee • talk • contributions • 19:49, 7 September 2015 (UTC)

I should also mention Eastern Red Cedar is in the same yard.— Vchimpanzee • talk • contributions • 22:51, 7 September 2015 (UTC)

My guess was that C. deodara would be seen as an exotic and luxurious plant in NC in the mid 1800s, so people probably talked about it, even if the name got a bit confused. But there's also the chance that C. deodara is not on the grounds, never was, and somehow the name "Deodora pine" still got into the literature. What is this print source you have? Does it happen to be a pamphlet from the house? Have you been to the house? Without seeing any other info, it's hard to say for sure, but I'd recommend trying to contact the estate. SemanticMantis (talk) 13:43, 8 September 2015 (UTC)

I have seen the house and both kinds of cedars are there. I think. There was a magazine article written by a newspaper reporter.— Vchimpanzee • talk • contributions • 14:14, 8 September 2015 (UTC)

Here is a photo with the trees I saw. It's not good enough to make a positive identification.— Vchimpanzee • talk • contributions • 17:37, 8 September 2015 (UTC)

The droopy tips of the branches (especially the very top one) are the key recognition feature of a deodar cedar.

The usual English name (in England anyway) is deodar. We have three species of true cedar over here; the cedar of Lebanon, the blue Atlas cedar and the deodar. They can be easily distinguished by looking at the new growth at the tips of the branches and see whether the shoots turn-up, stick straight-out or turn-down. According to Alan Mitchell, the great guru of British tree-spotters; "ascending - Atlas, level - Lebanon, down - deodar". (A Field Guide to the Trees of Britain and Northern Europe p. 116). User:Vchimpanzee's photo above has droopy tips and the general shape of the tree conforms to the deodar "conic to narrow spire-top" and certainly looks like a deodar to me. The clincher would be if we could see the leading shoot at the very top which should droop downwards. Alansplodge (talk) 17:00, 9 September 2015 (UTC)