User talk:Marsian

The metric unit for weight is kg. The metric unit for thrust is kN. Forget about kgf, it is rarely used anymore. For official examples, see:

http://www.raf.mod.uk/rafwittering/harrier.htm http://www.baesystems.com/facts/programmes/airsystems/eurofighter.htm

Thank you for your information.

Firstly, for weight, I thought "kgf" and "kg" are the same units both discribed in SI as "kg m/s²". You can use whichever you like but I prefer to cralify that "this is not mass but weight". I believe we should use "kgf" for weight. Otherwise, I'd like to use mass.

When I was a high school student, I was so confused by "kg for weight" and later noticed it's better to use "kgf" insead of "kg". This is wiki, so some might rewrite my "kgf" in table to "kg" but I don't think "kgf" is harmful.

So, in my opinion, RAF and BAEsys both use "kgf for weight" but they write it just "kg".

Secondly, for thrust, some still use kgf(or kg) in Japan... See:Mitsubish Heavy Industries Aerospace Headquarters (http://www.mhi.co.jp/aero/english/index.htm) or JASDF fact sheets (http://www.jda.go.jp/jasdf/refs/factsht1e.htm).

Now I think it's better to use SI so I myself prefer "kg for mass" and "kN for thrust". However, especially for thrust, Japanese readers may not like kN... --Marsian 07:24, 2004 Jul 18 (UTC)

Thank you for the reply and the examples. The word 'weight' is ambiguous. That is because it is older than our modern understanding of physics which divides things into mass and force. Thus it is wrong to say weight=force always, or weight=mass always. But the more common usage is weight=mass. There are plenty of references about this. For example, the US organisation in charge of measurement says:

http://physics.nist.gov/Pubs/SP811/sec08.html

In commercial and everyday use, and especially in common parlance, weight is usually used as a synonym for mass. Thus the SI unit of the quantity weight used in this sense is the kilogram (kg) and the verb "to weigh" means "to determine the mass of" or "to have a mass of".

Examples:

"the child's weight is 23 kg"

"the briefcase weighs 6 kg"

"Net wt. 227 g"

The British laboratory for standards says:

http://www.npl.co.uk/force/faqs/forcemassdiffs.html

In the trading of goods, weight is taken to mean the same as mass, and is measured in kilograms ... unfortunately, weight has three meanings [force, mass, calibrated weightpiece] and care should always be taken to appreciate which one is meant in a particular context.

To take each of your points in turn...
1. Quote [I thought "kgf" and "kg" are the same units both discribed in SI as "kg m/s²".].
When Mitsubishi says that the Japanese F1 fighter has a thrust of 3,200 kg, they should have written 3,200 kgf (but better as 31 kN). So you are correct to think it is force.

When Mitsubishi says it has a "Gross weight of 13,000 kg", that is a correct SI reference to the mass of the aircraft. So you are not correct to think it is force.

2. Quote [You can use whichever you like but I prefer to cralify that "this is not mass but weight". I believe we should use "kgf" for weight. Otherwise, I'd like to use mass.]
No. Remember that the word 'weight' is ambiguous. In most cases it is a synonym for mass. So when you see that the weight of an aircraft is 26,000 lb, then you must translate that into kg.

3. Quote [When I was a high school student, I was so confused by "kg for weight" and later noticed it's better to use "kgf" insead of "kg". This is wiki, so some might rewrite my "kgf" in table to "kg" but I don't think "kgf" is harmful.]
It is understandable that you are confused, lots of people are. This topic is widely discussed. Just remember that the word 'weight' is ambiguous but it usually refers to mass. So it is correct to describe the 'weight' of the aircraft as kg.

3. Quote [for thrust, some still use kgf(or kg) in Japan]
You are correct to think that thrust described in terms of kg actually means kgf. It would be better still to calculate the kN value (1 kgf = 9.8 N) and write that.

4. Quote [especially for thrust, Japanese readers may not like kN]
Do not underestimate your readers. I did a quick search of google for Japan and found that kN is sometimes used for thrust. However, if you feel that is the way that you want to do it, then make sure it is kgf (not kg) for thrust and kg (not kgf) for weight.

5. Quote [RAF and BAEsys both use "kgf for weight" but they write it just "kg"]
No. They are using the word 'weight' to mean mass and are using kg correctly. They describe thrust in kN correctly too.

I hope that helps.
Bobblewik 14:19, 18 Jul 2004 (UTC)

Thank you very much. I'm so astonished to know "the more common usage is weight=mass"! I didn't know that!

• Japanese usage is completely different. In Japanese, we never use "Jyuryo(translation of weight maybe) = Shitsuryo(translation of mass)".
• I mean, "Jyuryo" is always [kg m/s²] and "Shitsuryo" is always [kg]. They are definitely not the same.

Now I understand RAF and BAEsys are both using SI, right?

Again, I'm grateful for your help. --Marsian 15:18, 2004 Jul 18 (UTC)

Quote [RAF and BAEsys are both using SI]

In the case of 'weight' in kg and 'thrust' in kN, yes they are both using SI.

Bobblewik 12:07, 21 Jul 2004 (UTC)

RLM aircraft designation system

Hi - although it's quite common to find Ju87, Ju-87, Ju.87 in various sources (including some German ones from the period) "Ju 87" is simply the most correct form, since it's the one that the RLM assigned.

The best sources on this are in print (and in German), but on-line you can find the specification explained here (http://www.historic-battles.com/Articles/Aircraft_Designations_WW2.htm) and here (http://www.hazegray.org/faq/ram5.htm). Hope this helps! --Rlandmann 23:21, 26 Jul 2004 (UTC)

No problem. One thing, though - it seems to me that Ju87, Fw190, Bf109 seem to be the normal way of writing these designations in Japanese publications - I note it seems to be the norm in the various Shiwaku Nohara works and Koku Fan issues that I've seen. Japanese Wikipedia might have to choose between strict accuracy to the German standards and what's going to be familiar to Japanese readers.

In the same way, English Wikipedia has had to choose between the strictly accurate "Type 97 Carrier Attack Bomber" and the more familiar "B5N" designation. --Rlandmann 06:34, 27 Jul 2004 (UTC)

Interwiki order

Regarding the order of interwikis: I still favor putting them on alphabetical order of code, however, the majority once decided for alphabetical order on alphabet, so that's what I programmed the bot to do. If there is a decision to change that, I'd gladly hear it, until then, I will keep to it, and let you do whatever you want. - Andre Engels 16:36, 2 Apr 2005 (UTC)

Really, 'a good model' is too much honour for me. At times I wonder how people here keep standing me with my irrational behaviour and angriness attacks. But I guess I've done so much by now that it compensates even that. - Andre Engels 22:28, 3 Apr 2005 (UTC)