Guess The Efficiency of Han Dynasty Crossbow
The efficiency of an archery equipment is the percentage of energy that is transferred from the bow to the arrow. As you should know, there is probably no such thing as a 100% efficiency value. But some bows can transfer energy better than the other.
A longbow has a rather good efficiency (90%) and a crossbow is probably worse than that. However, as of recently, I have discovered that the crossbows are not as inefficient as what I used to think. Although still relatively short, a Han Dynasty Crossbow actually have around 23 inches of draw-length, with around 18-19 inches powerstroke. The bolt was also lighter than what I have initially thought; the bolts were around 55 to 60 grams rather than 200 grams. Finally, the Chinese used goose fat to lower the friction.
I need a professional guesstimation of what is the Efficiency Value of the Han Dynasty Crossbow.
I assumed the value of .73 or 73%. This is quite consistent, since the value is lesser than that of the longbow (90%), but not horribly so.
What's the number that you would guess? Just remember that the Chinese crossbows have some advantages that make up for their disadvantages.
A longbow has a rather good efficiency (90%) and a crossbow is probably worse than that. However, as of recently, I have discovered that the crossbows are not as inefficient as what I used to think. Although still relatively short, a Han Dynasty Crossbow actually have around 23 inches of draw-length, with around 18-19 inches powerstroke. The bolt was also lighter than what I have initially thought; the bolts were around 55 to 60 grams rather than 200 grams. Finally, the Chinese used goose fat to lower the friction.
I need a professional guesstimation of what is the Efficiency Value of the Han Dynasty Crossbow.
I assumed the value of .73 or 73%. This is quite consistent, since the value is lesser than that of the longbow (90%), but not horribly so.
What's the number that you would guess? Just remember that the Chinese crossbows have some advantages that make up for their disadvantages.
longbow efficiency 90% ??? in what movie ?
From the design of the crossbows, we can infer that the quarrels were double fletched. From the design of the boxes used to carry quarrels for hunting, we can infer that hunting quarrels were around 6mm in diameter and around 20cm long. We can infer that they were made of wood and the tips were iron at around 5 grams. Since the prods were attached with a slight downward inclination, we can infer that the string was in contact with the top of the wood trough for the whole trajectory of the release. The design of the mechanism shows that the quarrel was placed at the trigger and not knocked off the end of the crossbow like modern Yunnan crossbows.
My guess is that that given the limitations of the heavy bronze mechanism, which absorbs a proportion of the energy of the prod at release, the Han crossbow might not have achieved more than 50% - 70% of the efficiency of a modern sports crossbow.
My guess is that that given the limitations of the heavy bronze mechanism, which absorbs a proportion of the energy of the prod at release, the Han crossbow might not have achieved more than 50% - 70% of the efficiency of a modern sports crossbow.
Then what would be your estimate for the efficiency of the longbow, Osmiu? :wink:osmiu wrote:
longbow efficiency 90% ??? in what movie ?
Also, thank you very much for your estimation Mr. Stephen Selby.
Usually wooden bows store about 85% of the drawweight.
The efficiency of a longbow is about 65 - 75%. A very well done wooden bow has an efficiency of about 85%.
Michael
The efficiency of a longbow is about 65 - 75%. A very well done wooden bow has an efficiency of about 85%.
Michael
my estimation ? 50-60% .TheAzn wrote:
Then what would be your estimate for the efficiency of the longbow, Osmiu?
in my country , we do not have osage orange and yew is protected by law . and it is verry verry rare , anyway . one of the best choice the longbowmakers have is elm . and the skill of the makers is not that great . I've seen that bows . Have a bad efficiency . Some of them are better, some of them are worst . I don't do math for them , but my estimation is about 50-60% eficiency . I don't talk here about flight shooting selfbow that desintegrate therselfse after 10 shoots , but about regular , target shooting , common longbows . selfbows .
ps : I do not talk about X from US who have a osage lonbow made by Y , verry thin etc etc ... I talk about what we have here . so , if someone of this planet have a longbow with , let say 85% efficiency , we cannot say that all longbows have that efficiency . my opinion .
You don?t need osage or yew for to make a high efficient selfbow. Woods like spindlewood, hawthorn, blackthorn........etc. are as well or better like yew or osage.
It?s all a question of a good bow stave, a clever and well thought over design. Add some heat- treating and you?ve got it.
It?s a fairytale that a good wooden flightbow will break down after some shots. There are extremely designed flightbows that are really breaking down after some shots, but these are test- bows for to check out the limits.
I?ve done my first- flightbows this spring, I?ve shot them more than about 300 times, no sign of damage.
I know about bowyers having done wooden flightbows lasting for years.
I know, usually it?s hard to believe for plastic- fibre- and horn- bowyers to be outperformed by selfbows.
Look out for the US- National flights the upcoming weekend.
Michael
It?s all a question of a good bow stave, a clever and well thought over design. Add some heat- treating and you?ve got it.
It?s a fairytale that a good wooden flightbow will break down after some shots. There are extremely designed flightbows that are really breaking down after some shots, but these are test- bows for to check out the limits.
I?ve done my first- flightbows this spring, I?ve shot them more than about 300 times, no sign of damage.
I know about bowyers having done wooden flightbows lasting for years.
I know, usually it?s hard to believe for plastic- fibre- and horn- bowyers to be outperformed by selfbows.
Look out for the US- National flights the upcoming weekend.
Michael
I throwed with overdraw nearly 400 m (tape measured) with a verry cheap plastic bow . a series product , just a target bow (not a flight one) , made in China .
on the other hand , some selfbowmakers in here , bigmouths on the net , with 80m/s in cronograpf (they say !) ... barely reached 150 m on the field .
loooooooooooooool
so ... who outperformed who ?
they started testing again , and again , with their supersonic selfbows (on the paper !) and they still struggle to pass the 200 meter barrier .
so ... I just don't feel like I was outperform by anybody . with my series , plastic , China target bow .
but ... and that is the catch ! they wannna proove . i don't understand exactly what , but desperately they wannna proove .
good luck , Michael . maybe you are the last white hope for our desperate selfbow makers . goodspeed , and bring back life into them . give them hope . because they needed really bad .
on the other hand , some selfbowmakers in here , bigmouths on the net , with 80m/s in cronograpf (they say !) ... barely reached 150 m on the field .
loooooooooooooool
so ... who outperformed who ?
they started testing again , and again , with their supersonic selfbows (on the paper !) and they still struggle to pass the 200 meter barrier .
so ... I just don't feel like I was outperform by anybody . with my series , plastic , China target bow .
but ... and that is the catch ! they wannna proove . i don't understand exactly what , but desperately they wannna proove .
good luck , Michael . maybe you are the last white hope for our desperate selfbow makers . goodspeed , and bring back life into them . give them hope . because they needed really bad .
Arrogant as plastic- fibre archers are usual, look out for the upcoming US National flights. Happy awareness!?
Michael
Michael
looool
me ? what for ? I don't wanna desperately proove anything . anyway , I gave up flight shooting some time ago .
me ? what for ? I don't wanna desperately proove anything . anyway , I gave up flight shooting some time ago .