Warbow FPS?

[cool_98_555]

Hello Everyone.  Just out of curiosity, I was wondering if anyone ever shot a warbow through a chrono and clocked the fps.  I would be curious as to what the fps would be for a minimum of 100# shooting a true war arrow, and also a more modern carbon arrow with a heavy gpi rating like 10gpi+ and something like a 300 or 250 spine.

Looking forward to the results! 

[adb]

Never done it... and not interested in speed. More concerned with cast. Would be interesting to know fps, however.

[Thesquirrelslinger]

Big, heavy arrows do not need as much velocity to get the hitting power and KE of a normal (lighter) arrow.
KE= penetration/damage.

[adb]

Big, heavy arrows do not have as much velocity, but they have more momentum. Momentum is mass X velocity. And yes, it will have more kinetic energy, which is the energy an object possesses due to its motion. I think that's what you were trying to say?

As an example... would you rather get hit in the head with a golf ball going 50 mph, or a ping pong ball going 100 mph? I'll take the ping pong ball, thank you very much. It's similar with war arrows. They're not travelling nearly as fast as a carbon fiber arrow shot from a static recurve, but they hit much harder (and penetrate more) due to their greater mass. For me (shooting war bows), I could care less what the velocity is. If I get a cast of 200 yards or better with 60+ gram livery arrows, I'm a happy camper. Knowing the velocity would be interesting, however.

There was a TV series a while back... I think it was called "The Weapons That Made Britain" and there was a program on the longbow. They did some testing on penetration and velocity, etc. It was interesting. I think if you google it on you tube, you'll find it. They did some velocity testing with a Doppler radar(?) with Mark Stretton shooting a heavy draw weight war bow.

[adb]

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.

[twisted hickory]

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.

You would get a pass thru on a rhino!

[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]

Big, heavy arrows do not need as much velocity to get the hitting power and KE of a normal (lighter) arrow.
KE= penetration/damage.

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]

Big, heavy arrows do not need as much velocity to get the hitting power and KE of a normal (lighter) arrow.
KE= penetration/damage.

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.

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]

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.

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.

[Thesquirrelslinger]

Well, if I break all your ribs with a big heavy arrow... You are gonna have some fun swinging a sword. Or if I only break 1 or 2 ribs, or break your arm.

-Squirrel

[CaptainBeaky]

...it's not KE that kills with an arrow, it's penetration. KE is perhaps significant using a rifle, but not an arrow.

Quite  - see my point regarding momentum being essential to penetration above - although the example was aimed more at the "could the warbow arrow penetrate armour or not?" argument.

[llkinak]

Late post, I know, but I just got to it and thought I'd address the initial question.
I have a 120# tri-lam.  Maple back, purple heart core, ipe, belly.  It's about 74" nock to nock and 76" overall.
Parallel 3/8 inch birch arrows in the 900 grain range are going 170-175 fps 10 feet from the "muzzle".
A 1/2 inch tapered ash arrow weighing 1296 grains was in the 148.5 fps range, again about 10 feet away.
Chrony Chronograph on an indoor range at the local Sportsman's Warehouse.  I can't vouch for how often they calibrate the machine.  The bow was virtually brand new at the time.
I chronographed them simply out of academic interest.  I agree with those who think it doesn't matter all that much in the end with heavy arrows.  Shape and sharpness of the heads would probably matter a great deal, however, much more so than velocity as far as penetrating through unarmored critters is concerned. 

[Thesquirrelslinger]

Thanks for the data. IMO I would rather stop someone by literally knocking them back with an arrow than killing, b/c the kill is not instant.
I wonder if you could hunt with a warbow? use some big arse broadheads, maybe 2 inches wide or so?

[adb]

You could certainly hunt with a warbow, but I wouldn't. It'd be like killing flies with a hammer... you could do it, but there are much better tools. Accuracy and shot placement are much more important. A pass through is a pass through, regardless of draw weight. Broadheads here can't have barbs, and must be 7/8" wide minimum.

Hunting for me is all about providing a quick clean kill. The animal you're hunting deserves that. Go with the equipment that you can shoot best... consistently. If you can put an arrow in a 6" pie plate at 20 yards every shot with a warbow... go for it.