Externet Posted January 12, 2015 Share Posted January 12, 2015 Hi. Creating this thread to not distort one related to a baseball and an arm... A crossbow of a given fixed force. An arrow reaches say 100 metres. A lighter arrow of same dimensions/aerodynamics will reach farther ? A heavier arrow of same dimensions/aerodynamics will reach farther ? (not about lethality/penetration on impact) For sure, an untralight arrow made of paper will not reach farther. For sure, a heavy arrow made of lead will not reach farther. How is its weight 'tuned' fox maximum flight distance ? Link to comment Share on other sites More sharing options...
Delta1212 Posted January 15, 2015 Share Posted January 15, 2015 It comes down to air resistance. The lighter it is, the greater the acceleration from your fixed force, but the greater the effect of air resistance will be over the distance of the flight. Your paper arrow actually would fly much farther if you shot it in a vacuum. So you need to calculate the air resistance felt by your projectile and 'tune' the mass against that value so that your fixed force provides the maximum distance. Link to comment Share on other sites More sharing options...
imatfaal Posted January 15, 2015 Share Posted January 15, 2015 Externet - it is exactly the same equations as I gave in the baseball thread. The crosssectional area of an arrow is a disc (unless it is a bladed head) - so this is identical to a sphere. But you don't specify your arrows for maximal length - you want penetration at the sort of distance that an average archer can hit something. 50 yards or so would be ideal. The pull on the bow string would be around 100 pounds. You would need to get one of the engineers (studiot! bignose! strange! ) on the site to get you an idea of what you need to maximise in order to get penetration. You could have a heavy arrow with low energy or a lighter arrow with high energy - both with same momentum. Alternative view - you could have two arrows with same energy but different momenta. Your bow has a force over a distance sort of arrow delivery system - which is work - ie energy change so like the baseball you might be best to model basis 50-100 joules added energy. Link to comment Share on other sites More sharing options...
Externet Posted January 15, 2015 Author Share Posted January 15, 2015 Thanks. Yes, the equations apply the same; I believe the 'fixed' force of a crossbow is different than an arm. The arm will not transfer maximum nor constant force to the ball for different ball weights, specially the paper/lead extremes. ('Impedance mismatching') Link to comment Share on other sites More sharing options...
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