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Longbow - the arrowstorm revisited

Started by Erpingham, April 21, 2014, 11:33:23 AM

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Imperial Dave

#30
Quote from: Patrick Waterson on April 24, 2014, 11:21:21 AM

Absolutely correct for drawing to the right ear.  I have found that drawing to the right shoulder (really as far as you can go) is different - try sometime.  This is best done with a reversed grip on the string - palm towards you - otherwise the release can be problematic because the fingertips brush whatever you are wearing.  What put me onto this was some depictions of Egyptian chariot archers doing the same.

Interesting, never tried drawing to the shoulder.

As an additonal comment we always used a 2 or 3 fingered draw although I did see some archers using a thumb draw which I didnt like at all
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Patrick Waterson

Interesting to note the accounts of the draw technique in the Wikipedia article Anthony mentioned (and helps to maintain - good work, Anthony).

Quote
A record of how boys and men trained to use the bows with high draw weights survives from the reign of Henry VII.

    [My yeoman father] taught me how to draw, how to lay my body in my bow ... not to draw with strength of arms as divers other nations do ... I had my bows bought me according to my age and strength, as I increased in them, so my bows were made bigger and bigger. For men shall never shoot well unless they be brought up to it.
    —Hugh Latimer.

What Latimer meant when he describes laying his body into the bow was described thus:

    the Englishman did not keep his left hand steady, and draw his bow with his right; but keeping his right at rest upon the nerve, he pressed the whole weight of his body into the horns of his bow. Hence probably arose the phrase "bending the bow," and the French of "drawing" one.
    —W. Gilpin.


This 'chest expander' style of drawing - sorry, bending - seems very similar to the method I fell into more or less by accident.
"Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing had happened." - Winston Churchill

Imperial Dave

Interesting, my taught style was an amalgam of the two.

I was taught to "push out" with my left arm (straightening it as I went) and at the same time raising the bow up to eye level and drawing the left arm back all in one smooth movement
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Chuck the Grey

Having limited knowledge and experience of archery, I have a question for the more knowledgeable members of our society. I was wondering how flat the trajectory of the English warbow was at ranges of 100 yards, 200 yards, 300 yards, etc. A flatter trajectory means a lower angle of departure for the arrow and, as has been previously discussed, that would affect the ability of multiple ranks to fire at once. Consideration of the trajectory at various ranges might help to understand the tactical utilization of the longbow.

Justin Swanton

#34
My own experience is with a 45 pound bow. At 100 yards you are sighting the target directly using a sighting pin with the bow raised a little, giving the arrow a slight curve in its flight. I imagine that at that range, a 100+ pound longbow would shoot an arrow in an almost straight line. At 200 yards there would be a noticeable parabolic curve, but I think you would raise your bow appreciably only at a greater range.

One thing to keep in mind is that the extent to which you raise your bow is in inverse proportion to the extra distance the arrow travels. In other words, raising the bow a little will make the arrow travel much further; raise the bow a little more by the same increment and the distance the arrow travels will increase, but by less. The point is reached where you raise the bow and the distance the arrow travels hardly changes. Raising the bow after that decreases the distance the arrow travels.

This useful when doing overhead shooting at extreme range: if you raise the bow to approximately the right elevation, the arrows will all tend to land in the same place, even if the angle the bow is raised varies slightly between one shot and the next.

Imperial Dave

45 degrees is the optimum angle of elevation for a bow to achieve maximum distance.

Decrease the angle and the arrows travel less distance, increase the angle and they drop shorter but with a much better vertical "dropping" effect

In terms of distance on the flat shot, I have used traditional longbows from 35 to 45lbs in draw-weight and it all depends on the type of arrow you use and the fletching used but I think we have covered this aspect of archery esewhere recently
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Patrick Waterson

Quote from: Holly on May 07, 2014, 08:08:59 AM

Decrease the angle and the arrows travel less distance, increase the angle and they drop shorter but with a much better vertical "dropping" effect


Did anyone count the number of seconds for a maximum range shot to hit the ground or target?

Any thoughts as to the approximate range cut-off point when this approach would cease to be useful?  With 45 degrees giving maximum distance, and flight time being presumably about the same for angles above 45 degrees, one can see this approach working for a number of volleys and coming in (as Dave points out) at a steeper angle each time, which the targets (opponents) may not anticipate.  If the targets are slowed as a result of the first couple of volleys then one can really get to work with subsequent volleys, making the most of the 'killing zone'.
"Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing had happened." - Winston Churchill

Imperial Dave

Quote from: Patrick Waterson on May 07, 2014, 11:16:11 AM
Quote from: Holly on May 07, 2014, 08:08:59 AM

Decrease the angle and the arrows travel less distance, increase the angle and they drop shorter but with a much better vertical "dropping" effect


Did anyone count the number of seconds for a maximum range shot to hit the ground or target?

Any thoughts as to the approximate range cut-off point when this approach would cease to be useful?  With 45 degrees giving maximum distance, and flight time being presumably about the same for angles above 45 degrees, one can see this approach working for a number of volleys and coming in (as Dave points out) at a steeper angle each time, which the targets (opponents) may not anticipate.  If the targets are slowed as a result of the first couple of volleys then one can really get to work with subsequent volleys, making the most of the 'killing zone'.

Duration of arrow shot will depend on the weight of the arrow used along with the power of the bow (and archer!). I think last time I measured speed of shot for our reenactment group was around 100fps for rubber blunt "flu flu" fletched arrows and around 200fps for steel tipped speed fletching from the top of my memory. Therefore if you shoot with said steel tipped, speed fletching "combat" arrows its around 1-2 seconds for a 100yards, 3-4 seconds for 200 yards and 5-6 seconds for 300 yards.

Re the angle of shot, we constantly adjusted our angle of fire when shooting into combat as the opposing infantry advanced to contact with our own infantry. In this kind of instance it was always angled and indirect. If we had chance before the reenactment engagement, we would also pre-determine range of shot taking into account lay of the land, weather/wind direction and our own ability!   
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Erpingham

This information from Saxton Pope may be useful :

A light arrow from a heavy bow, say a sixty-five pound yew bow, travels at an initial velocity of one hundred and fifty feet per second, as determined by a stopwatch.

Shooting at one hundred yards, such an arrow is discharged at an angle of eight degrees, and describes a parabola twelve to fifteen feet high at its crest. Its time in transit is of approximately two and one-fifth seconds.

Shooting straight up, such an arrow goes about three hundred and fifty feet high, and requires eight seconds for the round trip.


There is also a graph in the Great Warbow that shows a 190m. range needs a 30 degree elevation.

As the archers among us have already pointed out, ranges below maximum can be achieved by increasing or decreasing the elevation of the bow.  It would be theoretically possible for the first two or three ranks to continue to flatten their trajectory but subsequent ranks to switch to steeper elevation when shooting a flattening trajectory over their comrades became uncertain.  We can imagine that a target at 100yds might be receiving both flat trajectory and plunging shots at the same time.  However, this is another area we have insufficient evidence on, so how one might co-ordinate such shooting must remain speculative.

Imperial Dave

Quote from: Erpingham on May 07, 2014, 12:10:37 PM
This information from Saxton Pope may be useful :

A light arrow from a heavy bow, say a sixty-five pound yew bow, travels at an initial velocity of one hundred and fifty feet per second, as determined by a stopwatch.

Shooting at one hundred yards, such an arrow is discharged at an angle of eight degrees, and describes a parabola twelve to fifteen feet high at its crest. Its time in transit is of approximately two and one-fifth seconds.


If nothing else I am both pleased with my memory and the corroboration of my own observations with the info above.... pretty close although I didnt specifiy the angle of dangle for the shots!

Re the measurement of velocity there are a few specialist units for doing this accurately such as 

http://www.amazon.com/Sports-Sensors-Inc-ASR362-Arrowspeed/dp/B000BZ1L66

I have a simple tripod mounted version
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Nick Harbud

To answer the questions regarding longbow ballistics, I have programmed all this into a spreadsheet.  Using Hardy & Strickland's Arrow 2 data (96g arrow shot at ~60m/s) you arrive at the following:

100m requires 9 degrees elevation, maximum height reached is 4.5m (~15 ft).
200m requires 22 degrees elevation, maximum height reached is 22m (~70 ft)

Range at 45 degrees is ~270m, approximately the same as the maximum achieved by re-enactors with very powerful longbows.

Note that although both middle and long distance trajectories are pretty flat, the 200m shot is likely to be more affected by wind.

Hope this helps.
Nick Harbud

Patrick Waterson

Thank you, gentlemen.

I find Saxton Pope's figures intriguing:
Quote
Shooting at one hundred yards, such an arrow is discharged at an angle of eight degrees, and describes a parabola twelve to fifteen feet high at its crest. Its time in transit is of approximately two and one-fifth seconds.

Shooting straight up, such an arrow goes about three hundred and fifty feet high, and requires eight seconds for the round trip.


The arrow going straight up decelerates to zero then increases speed according to gravity.  This seems to add about five seconds to the flight time.  If an arrow is shot at, say, 70 degrees or so, am I right in thinking it will decelerate, but not to zero, but rather in much the same way as an arrow following a 45-degree trajectory?
"Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing had happened." - Winston Churchill

Imperial Dave

I am not sure Patrick, there must be a "tipping point" at which the arrow decelerates to zero or near zero but this may not necessarily be just 90degrees to the horizontal

I think that the arrow decelerates at a proportional rate at degrees of angle above 0 to the horizontal till it eventually reaches near zero at a certain angle

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Erpingham

Quote from: Holly on May 07, 2014, 06:53:26 PM
I am not sure Patrick, there must be a "tipping point" at which the arrow decelerates to zero or near zero but this may not necessarily be just 90degrees to the horizontal

falling back on the O level Physics here but I don't think it falls to zero unless you shoot it pretty much straight up.  Assuming a still day, you've got three force vectors; shooting, drag and gravity.  You need to resolve those three to get trajectory, which should be essentially parabollic.  But don't ask me how to do that - they make computer programmes for that :)

Patrick Waterson

This is my thinking, too (and probably the same O-level physics): provided the arrow is still moving forward, even parabolically or hyperbolically, it does not lose time and energy dropping its speed to zero under the effects of gravity.  At angles above 45 degrees the flight time should be about the same as for 45 degrees and the 'total gravity impedance' or net drag from this still-not-really-understood force should thus be about the same until one reaches the very-near-90-degrees mark.

Some day someone will presumably fit a really small accelerometer with an on-board recording chip to an arrow and resolve the question.
"Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing had happened." - Winston Churchill