Main Discussion Area > English Warbow
Warbow FPS?
twisted hickory:
--- Quote from: adb on April 11, 2013, 06:54:06 pm ---I was re-watching the Doc on 'The Weapons That Made Britain - The Longbow' and on episode 2 they were doing some penetration testing. With Mark Stretton shooting a 150# warbow, they indicated 52 meters per second initial velocity (which is about 170 fps), but they didn't say how heavy the arrow was. I'd guess he would probably be shooting at least a 65 gram arrow, but it could be much more. That's decently impressive with a heavy arrow. That would be average for a target weight arrow, but with the increased mass of a heavy arrow, that would give it very good momentum. IMHO, the arrow head they were using for the armour penetration test was rubbish. With a proper heavy head, and a 1/4# arrow, I think the results would have been different.
--- End quote ---
You would get a pass thru on a rhino! :o :o :o :o
mikekeswick:
It's ok testing these bows to see if they shoot through armour but that doesn't really matter. It was the French horse's we were interested in hitting. A knight without a horse is next to useless.
A 'warbow' if made correctly will do the same as a 'normal weight' bow whern everything is scaled in proportion.
CaptainBeaky:
--- Quote from: Thesquirrelslinger on April 07, 2013, 10:42:45 pm ---Big, heavy arrows do not need as much velocity to get the hitting power and KE of a normal (lighter) arrow.
KE= penetration/damage.
--- End quote ---
Momentum = mv (mass x velocity) and is what you need for penetration with a set frontal area - the more mass you have, the higher the resistance to a change in velocity, whether due to air resistance or due to penetration into the target.
Kinetic energy = mv2 (mass x velocity x velocity) and is what causes impact damage to the target (as distinct from penetrating/cutting tissue damage from the sharp edges of a broadhead).
Illustration:
2 arrows - one weighing 300gr travelling at 300 f/s, (carbon out of a compound?), the other weighing 600gr travelling at 150f/s (warbow?)
They both have the same momentum, but the lighter arrow has twice the kinetic energy of the heavier arrow at half the velocity.
If both arrows had the same point profile and cross-section (OK, unrealistic, but bear with me), they would penetrate to the same depth, but the lighter arrow would impart a heavier impact.
Switching back to Planet Reality, where the lighter arrow has a much smaller cross section, the lighter, faster arrow would quite possibly penetrate all the way through, whereat the extra kinetic energy would be less than gainfully employed in making a hole in the scenery. The heavy arrow, on the other hand, would be more likely to stop in the target, passing all it's energy into the target - energy transfer is the key to stopping power.
Your 1/4lb warbow arrow hitting the aforementioned armoured knight downrange at 100f/s, not even penetrating the armour, but passing all it's kinetic energy to the target, would have the same energy of impact as a 12lb sledgehammer swung at 15f/s (try swinging one at this speed - it's hard work!) - more than enough to knock said knight over.
adb:
--- Quote from: CaptainBeaky on April 12, 2013, 06:29:11 am ---
--- Quote from: Thesquirrelslinger on April 07, 2013, 10:42:45 pm ---Big, heavy arrows do not need as much velocity to get the hitting power and KE of a normal (lighter) arrow.
KE= penetration/damage.
--- End quote ---
Momentum = mv (mass x velocity) and is what you need for penetration with a set frontal area - the more mass you have, the higher the resistance to a change in velocity, whether due to air resistance or due to penetration into the target.
Kinetic energy = mv2 (mass x velocity x velocity) and is what causes impact damage to the target (as distinct from penetrating/cutting tissue damage from the sharp edges of a broadhead).
Illustration:
2 arrows - one weighing 300gr travelling at 300 f/s, (carbon out of a compound?), the other weighing 600gr travelling at 150f/s (warbow?)
They both have the same momentum, but the lighter arrow has twice the kinetic energy of the heavier arrow at half the velocity.
If both arrows had the same point profile and cross-section (OK, unrealistic, but bear with me), they would penetrate to the same depth, but the lighter arrow would impart a heavier impact.
Switching back to Planet Reality, where the lighter arrow has a much smaller cross section, the lighter, faster arrow would quite possibly penetrate all the way through, whereat the extra kinetic energy would be less than gainfully employed in making a hole in the scenery. The heavy arrow, on the other hand, would be more likely to stop in the target, passing all it's energy into the target - energy transfer is the key to stopping power.
Your 1/4lb warbow arrow hitting the aforementioned armoured knight downrange at 100f/s, not even penetrating the armour, but passing all it's kinetic energy to the target, would have the same energy of impact as a 12lb sledgehammer swung at 15f/s (try swinging one at this speed - it's hard work!) - more than enough to knock said knight over.
--- End quote ---
I agree with everything you've written. But, it's not KE that kills with an arrow, it's penetration. KE is perhaps significant using a rifle, but not an arrow.
adb:
--- Quote from: mikekeswick on April 12, 2013, 04:24:11 am ---It's ok testing these bows to see if they shoot through armour but that doesn't really matter. It was the French horse's we were interested in hitting. A knight without a horse is next to useless.
A 'warbow' if made correctly will do the same as a 'normal weight' bow whern everything is scaled in proportion.
--- End quote ---
Agreed. I believe the whole armour penetration thing is a bit of a myth. As has been demonstrated, it was only possible at extremely close range (20 yards). The whole point of medieval or Tudor military archery was the same as modern artillery: to soften the enemy from a distance with massed volley. The arrows where much more effective on the soft bits and the horses. Yes, an unhorsed enemy knight is much less effective on foot.
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