Anemometer or speedmeter widget ?

[Cortek56]

Hello,

I note that in KSP, the speed is only given in m/s.

But some people are accustomed to data in Miles / h Km / h or knots, and the spatial conquest in parsec or light speed ...

Here's my idea: a small gadget will display and configurable to display in real time the different speeds preselected by the user.

What do you think about?

Kerbaly,

[vexx32]

m/s is the SI unit for all physics and aerospace calculations involving speeds, except in atmospheric-only flight, where it seems knots is the norm. I have heard previously that the devs wanted to keep things simple in that department and were opposed to the idea of adding a plethora of units to use, but that may or may not change in the future. I personally see no real need to add any more than a single measurement unit, especially as regardless of what speed measurement you use, bigger numbers means faster speeds, and that's really all there is to it.

[Dunbaratu]

Three problems:

1 : @Cortek56: The title of the suggestion is wrong. Anemometers are just things that measure airspeed. The fact that our culture tends to measure it in knots is not part of the difference between anemometers and speedometers. Basically we already HAVE an anemometer in the game - it's called "putting the navball in 'surface' mode" which gives you your speed relative to the volume of atmosphere that's 'attached' to the surface, since KSP has no wind.

2: @vexx32: You implied "knots" is an SI term. (Saying m/s is the SI term except in atmospheric flight where it's knots). It isn't. Knots is part of the culture of the air travel industry, where the tendency in the early days to borrow naval terms for airplanes, combined with the need to make an international standard because you cross national borders so readily in an airplane, meant that the naval international standard ended up becoming the airplane international standard, in use even in those countries where the country had been metric for a long time. This is analogous to the fact that anyone who wants to become a pilot or a traffic controller must learn English so that all communication is internationally done in the same language no matter what airport you're at.

3: @vexx32 : While there isn't need for multiple different units, there *is* a need to label the units that do exist, since the claim that all the units are in SI standards in KSP is provably false when you see how the numbers interact with each other There's scaling factors in the game that prove that some measures are 1000 times out of scale from other measures. The interaction between volume, mass, and thrust listed for parts and how the math works out when you try using them proves they can't all be SI units. One possibility that does work is if mass is in megagrams, thrust is in kilonewtons, and volume is in liters. (SI units would be kilograms, newtons, and liters).

[Kasuha]

and volume is in liters. (SI units would be kilograms, newtons, and liters).

kiloNewton is an SI unit. Litre is not an SI unit, SI unit for volume is cubic meter. Litre and tonne are on the same level of "non-SI units accepted for use with SI".

[see also: wikipedia]

Besides, I am not aware of any volume units in KSP. Fuel units are mass equivalents specific to given fuel, there is no reason to assume they mean volume.

Edited March 21, 2014 by Kasuha

[Red Iron Crown]

As I understand it, liters and tonnes are not precisely SI only because they use non-standard names, the equivalent SI units are Mg and dm³.

I kinda wish volume was used in some calculations, would be nice to have realistic buoyancy in the oceans around.

[Dunbaratu]

kiloNewton is an SI unit. Litre is not an SI unit, SI unit for volume is cubic meter. Litre and tonne are on the same level of "non-SI units accepted for use with SI".

What you've done there is confuse "SI" with "Metric". SI is a subset of metric. In metric there's many many terms for force, all related to each other by powers of 10. In SI, the standards pick just one of them and stick with it so that all your figures will be in the same scale - and the one that SI picks is newtons, not kilonewtons. Then, also the international standards groups pick the SI unit as the one for which there will be a physical standard derived from something materially existent, and then all the other metric units will be derived by multiplying that unit or dividing that unit by powers of 10. So for example, the international standards for SI mass has a kilogram bar stored in a lab in France as the basis for all the other mass measures that are derived from it.

Oh, and a litre is very much like a kilonewton. It's not the SI unit but it is a metric unit derivable from the SI units. Specifically it's the volume that, if filled with water, would have a mass of 1 kilogram. Much like a kilonewton is the unit of force you'd get if you took the SI unit and multiplied it by 1000. It's not the SI unit, but is easily derivable from it.

Another way in which metric and SI differ is in where the 'base' unit sits on the powers of 10 scaling. In metric masses, the naming convention is to start from the gram and derive all the other mass units from that, so a kilogram is derived from the gram by multiplying by 1000. This is where the naming conventions come from and why 'gram' is the mass term that has no prefix. But in SI it's the other way around, and despite borrowing the same terminology as in metric, in SI the gram isn't in fact the base measure - it's derived. The kilogram is the base SI unit, and the gram is derived backward from that, by dividing the official kilogram definition by 1000.

But at any rate, this is all parenthetical to the point I made originally, which is that the claim that the units in the game don't need to be specified because they're metric is a false claim. They do need to be specified. You can't work out your TWR when mass, thrust, and gravity, are all unitless numbers, unless you know they are in the same exact scale from each other (and they aren't). When the gravioli detector tells you the gravity is 9.8, and you start to assume that means standard SI units, you'll be wrong when you come to the thrust and assume it's standard SI units (newtons) when it isn't.

The only reason I worked out that thrust was in kilonewtons was that I saw that mass was in tons, that gravity was 9.8 "thingies", assumed that 9.8 was m/s^2, and experimentally made several rockets until I got one that hovered in place at max thrust, knowing that would be a TWR of 1.0, then working backward from that to find out that the thrust was given in kilonewtons.

That's a silly amount of extra work to ask the user to do when you could just put a label on the unit in the display instead.

Edited March 22, 2014 by Steven Mading

[vexx32]

2: @vexx32: You implied "knots" is an SI term. (Saying m/s is the SI term except in atmospheric flight where it's knots). It isn't. Knots is part of the culture of the air travel industry, where the tendency in the early days to borrow naval terms for airplanes, combined with the need to make an international standard because you cross national borders so readily in an airplane, meant that the naval international standard ended up becoming the airplane international standard, in use even in those countries where the country had been metric for a long time. This is analogous to the fact that anyone who wants to become a pilot or a traffic controller must learn English so that all communication is internationally done in the same language no matter what airport you're

3: @vexx32 : While there isn't need for multiple different units, there *is* a need to label the units that do exist, since the claim that all the units are in SI standards in KSP is provably false when you see how the numbers interact with each other There's scaling factors in the game that prove that some measures are 1000 times out of scale from other measures. The interaction between volume, mass, and thrust listed for parts and how the math works out when you try using them proves they can't all be SI units. One possibility that does work is if mass is in megagrams, thrust is in kilonewtons, and volume is in liters. (SI units would be kilograms, newtons, and liters).

Ah, yeah, that first was an unintentional implication, sorry. I am fully aware knots is a non-standard measurement and so forth. I've done basic aerospace studies.

You are quite correct in that, yes. Many of KSP's units do need standardising (AFAIK, several units in KSP are ridiculously arbitrary at present), which is an additional reason why I'm against introducing alternate or further additional units as options to KSP. It's just going to confuse everyone even further, I think. Standardisation first, then we can talk about possible minor alterations first, I think.

[Kasuha]

What you've done there is confuse "SI" with "Metric". SI is a subset of metric.

The metric system is an internationally agreed decimal system of measurement that was originally based on the mètre des Archives and the kilogramme des Archives introduced by France in 1799. Over the years, the definitions of the metre and kilogram have been refined and the metric system has been extended to incorporate many more units. Although a number of variants of the metric system emerged in the late nineteenth and early twentieth centuries, the term is now often used as a synonym for "SI" or the "International System of Units"â€â€the official system of measurement in almost every country in the world.

A metric prefix or SI prefix is a unit prefix that precedes a basic unit of measure to indicate a decadic multiple or fraction of the unit.

...

Decimal multiplicative prefixes have been a feature of all forms of the metric system with many dating back to the system's introduction in the 1790s. Metric prefixes have even been pre-pended to non-metric units. Today the prefixes are standardized for use in the International System of Units (SI) by the International Bureau of Weights and Measures (BIPM) in resolutions dating from 1960 to 1991.

SI unit with SI prefix is still an SI unit, you know.

The only reason I worked out that thrust was in kilonewtons was that I saw that mass was in tons, that gravity was 9.8 "thingies", assumed that 9.8 was m/s^2, and experimentally made several rockets until I got one that hovered in place at max thrust, knowing that would be a TWR of 1.0, then working backward from that to find out that the thrust was given in kilonewtons.

That's a silly amount of extra work to ask the user to do when you could just put a label on the unit in the display instead.

It can be found it on Wiki. But I agree the game should definitely provide reasonable units in part descriptions.

Edited March 22, 2014 by Kasuha

[Sirrobert]

Besides, orbital speeds are in Km/second.

It'd become stupidly big numbers if you did that in km/hour

[Cortek56]

Thanks for that

[Murph]

m/s is the SI unit for all physics and aerospace calculations involving speeds, except in atmospheric-only flight, where it seems knots is the norm.

Knots are used because of their fundamental relationship to latitude. 1nm is 1 minute of latitude, which makes pencil and chart navigation easy, particularly with dead reckoning.

As for the original topic. I don't think there's any real benefit to having other speed units available for the space aspect of the game, although it wouldn't be particularly harmful either. It might be worthwhile to have knots and mach number for atmospheric flight, but I don't see that as a strong need.