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type 16 war arrow

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SimonUK:

--- Quote ---The thought goes like this. Drag is mostly produced by surface area of an object which is defined by radius squared. Mass is produced by volume which is defined by radius cubed. In some aquatic animals, for example, this produces a selection bias towards increased size because the extra volume you get contains a lot of muscle which is acquired for not that big an increase in surface area, and therefore drag. The result is that big aquatic animals are fast, and the blue whale, for example was only hunted from the 1930's onward for that reason.
--- End quote ---

A minor point, but I think this is wrong. The surface area is a function of the radius, not radius squared (surface area = length.2.pi.r). Volume is a function of the cross section area (length.pi.(r squared)).

I think the radius cubed is all to do with spheres.

Lloyd:
1st question, are you an engineer or a scientist? :D :D :D


"I have to say though that bitching about how good things were in the past is a peculiarly British pastime..."

couldn't disagree more. It's an element of human nature. As universal as the fact that we all breathe air and drink water

"I've been wondering about something for a while which was restimulated by your post. What if they didn't put the heaviest heads on, but the lightest possible ones?"

I think you always use the lightest heads available within the class of head you are using at the moment. If I'm shooting light horse I want to use type 7s which are probably a lot lighter than a 9a for example. But I still want the lightest type 9a on my arrows when I'm shooting at heavy horse. There is definitely it seems a "bigger is better" attitude in the development of heads. It would be very interesting to see a detailed analysis of the ballistic properties of all the different head types.

"Now, to my mind, for a galling arrow, the head doesn't need to be heavy, just strong enough to withstand the impact and hard enough to concentrate all the force at a point without deforming so that it has a chance to go through"

Absolutely. Galling arrows are to keep the other guys heads down and piss them off more than anything else. Probably good for irritating the horses too.

"Ascham said that ash was the material of choice because it gives a hell of a whallop (fierce heavy stripe is how I think he put it), which to me indicates that the job of providing weight to the arrow belonged, perhaps predominantly, to the shaft."

See my previous comments about the bigger or heavier is better syndrome. Since Ascham doesn't really talk about heads that much I'm not sure we can draw any conclusions from him on this particular subject.

"We also have an indication that fletches were 'long and low', from a welsh poem..."

I like low cut feathers for my arrows. Usually 1/2 to 5/8 high at the back and at least 8" long. I've done some swallow tails with 9.5" feathers.

"Where all this is going is that the trick might not be to add a heavy arrowhead- it'd be to use heavy wood and control the attitude of the thing in the air so it presents as little as possible of itself for as long as possible, as big aquatic animals do. What about taking the heaviest shaft you can find, put a bodkin head on which is strong enough to do withstand the impact without deforming, but no more, and experiment with 8.5inch fletches in terms both of height and position on the shaft? It'd still weigh in at over 1000grains and might travel a long way."

Interesting experiment, I'd be interested to see it in action. But, if it would have worked I think they would have figured it out, wouldn't they? And aren't you really restating your definition of a galling arrow?
I think there are things about war bows and war arrows that we have forgotten about and some of them probably can't be rediscovered until we let 500 guys with war bows kill a bunch of knights and horses. As I've said before I'll bet my life if it didn't work they wouldn't have done it. I think a universal principle of archery is that you want the lightest arrow that will do the job. How light is heavy enough for the particular job is the real question.

"I'd be surprised if this hasn't been done - its just that I haven't heard about it and I'm curious."
Me too. Good conversation!

ChrisD:
No Simon, it isn't wrong. I'll send the reference if you want - in a fascinating book on form and function in nature.

The reason we got taught about spheres in school is that its easier to start that way because there is only one variable to think about - the radius.

In the case of a cylinder, there are two variables - radius and height.The surface area is the area of the two ends (pi x r squared x 2) + the area of the shaft (2x pi x r x h). It still depends on r squared.

Hope that helps. ;D

C

SimonUK:
Yes Chris you're right, if you count the surface area of the ends of the cylinder you have to use r squared. Is that what you were saying? I thought you were talking about the surface area of the whole arrow, in which case the ends become negligible compared to the sides.

Volume is still not a function of r cubed.

ChrisD:
Simon, I think where you are getting hung up is by thinking of only one dimension as a radius. Ellipses have two radii, for example and in a cylinder, the traditional radius is regarded as one while height can be regarded as another (well diameter really).

Surface areas always get calculated on an a x b basis therefore the order of magnitude  called a square.
Volumes always get calculated on an a x b x c basis therefore the order of magnitude is called a cube.
 ;) ;) ;)
What you actually call the dimensions doesn't really matter - its simply a fact that discussing spheres is the easiest way to illustrate the point that surface area increases proportionately less than volume when you make things bigger - I was only trying to add an empirical perspective to the discussion which I haven't seen before because it is one way of seeing how arrows might get really heavy without necessarily looking so much bigger to the naked eye, especially with these super dense woods that Lloyd mentioned.

LLoyd I guess I'm neither scientist nor engineer - just a simple unsplicer of human tissue - which I endeavour to resplice when I'm done. I would say that my training has been heavily science based but I did spend a year doing tissue engineering work in a materials science lab and I still have a bit to do with those guys so I've got a nodding familiarity with some aspects of engineering and general aspects of biological systems at a cellular level. What it means is that I can get access to some interesting gew gaws if necessary - MR scanners, Instron machines and the like.

On the arrow shapes, my thoughts were driven on the basis that the narrowing in the distal part of the MR shafts, for example might have been designed according to the weight of the head in order to keep the thing as neutral as possible, with a dinky wee pointy head attached. What else can I say? An experiment to give a whirl and keep me out from under the nose of erindoors.

I have to say that I agree completely with the pragmatic principles which you have espoused on arrow manufacture and I'm sure that the ancient arrowsmiths would equally have used what worked best, even if they mightn't have been able to say precisely why.

C :)

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