Units for arrow speed?

[DrRalph]

People often quote feet per second for arrow speed - like CMB50s new bowtech at 322 fps. Meters per second (SI units) don't seem so popular, probably because the numbers are smaller (*0.3048) ie 322fps = 98.1456m/s (BTW you need another 2m/s to break 100m/s!)

I like kilometers per hour (km/h = m/s*3.6). Then CMBs arrows top 353.3 km/h : definitley Grand Prix speeds! :crazyeyes:

So take fps and x 1.09728 gives kph! (add roughly 10% - like GST)

It is easier to relate to, and is an even bigger number than fps! I move everyone change to kph, who's with me ? :) :)

Jim, can accurate sights work in kph?

[James Park]

Jim, can accurate sights work in kph?
All my calculations are done in M/sec. I show ft/sec simply because most archers use it. Could easily do kph.
Similarly, I use grams instead of grains (but I show grains, again for the same reason). Likewise millimeters and inches.
For distances, all the calculations are done using Metres, but I let the users have yards if they wish.
Similarly, you will generally find me talking about "mass" instead of "weight", and "velocity" instead of "speed".
I think we are a confused sport, unit-wise. I suspect even the French would use "ft/sec" for arrow velocity.

[DrRalph]

It is confusing. As and astrophysicist I think in cgs, and have to convert to MKS when talking to physicists, but this archery nonsense, driven by the US *voluntary* metrification failing completely, really ticks me off. Hence the facetious post. Sorry.

Still, when talking to non-archers about the sport, kph does seem to get the message over quite well.

[Rodger]

Hoyt IBO speeds with XT2000s and Cam+1/2 in kph:
ProTec 325
RazorTec 340
SuperTec (Spiral Cam) 362
UltraMag 335
UltraTec 338
ViperTec 329
XTec 340

They sound much faster! :D :o

PS CGS? MKS?? :-?

[James Park]

PS CGS? MKS?? :-?
Astronomers use: centimeters, grams, seconds (cgs)
Engineers use: Metres, kilograms, seconds (MKS)
Americams use: feet, pounds, seconds (imperial)
Archers use:just about all of them all at the same time (confused)
If you always use a given standard set it makes like very much easier to do calculations, and less likely that you will make an error.

[Axilla]

Being involved in civil and structural engineering for many years, I can't remember when we didn't use metric. If the goddamn USA would go completly to metric, this confusion would be mostly eliminated.

Tyres are a prime example of confused systems, width in millimetres, rim size in inches.

We should be thankful that the imperial lengths US use are consistant with other imperial length measures, not so with their volumes.

I vote for metres/sec, give us direct relation of speed to target distances, eg: 90m in roughly one second, etc.

[James Park]

At least the USA is consistent.
The UK seems to be stuck half way in between.
When I do calculations I just about always use MKS, and then do any conversions to other units later (and change units to MKS prior to calculations where necessary). The conversions are easy, it is trying to mix units in the calculations that gets remarkably dangerous.

[Marcus]

I find the swapping in games rather difficult also.
FITA=metres
ABA = metres
IFAA = yards
3DAAA = yards

grateful that 3DAAA is unmarked so I just guess in metres anyway.

for arrow speed I was describing to a bunch of designer customers yesterday that a bow travels around 100m per second. Personally I don't think that 360kph sounds that quick for a projectile weapon.

[Guy]

I was describing to a bunch of designer customers yesterday that a bow travels around 100m

You must have really spat it to throw it that far or did you use a catapult? Or did you mean the arrow? :D

[Marcus]

I forgot my sling :lol: