Instructables

Do bigger rods make better ammo?

Some guys here on Ibles told me that green rods make the best ammo for Knex guns, because they fly faster. Since then I always used green rods above blue or yellow ones. Others said that grey and red rods were way better because they hit harder. Which one is the best and why?

knexsniper15 years ago
this may seem like what osi is saying, but in a way, this is an add on to what he said. see, as osi said, the larger rods require more initial force to propel them from the barrel and to reach maximum velocity it can, which is very hard due to the fact that there are many forces acting against them including: - air resistance - the rods weren't aerodynamically designed to be projected - and gravity the smaller rods don't require as much initial force because of the lower mass, so when you put it into the velocity equation which i dont have right off the top of my head, but it will all be clear to you. now, to put it into a knexgunner's point of view, which i think you are asking from, the larger rods hit way way harder again due to the larger mass. so when an object with a larger mass strikes against another, it is exerting more force onto that object than an object of less mass such as small rods. another thing to take into consideration is that the longer rods are not affected and more than the smaller rods are by gravity, but since they are longer, they bend more. same with a bow and arrow. the arrow travels so fast that you are unable to see it, but it bends in the air. same with the longer rods, when they bend, they are more likel to be affected by air resistance because a larger surface area is in contact with the opposing air that is applying force against it. in other words, the longer rods are not as aerodynamic as the smaller rods. so the smaller rods tend to go farther, yet not pack as much a punch. i really hope this helps. (i'm really good at physics :D ) and i really hope you didn't laugh every time is said the word "rod" cause i know i would have XD sorry this was so long, but i had a lot to say to answer your question.
TigerNod (author)  knexsniper15 years ago
One question: You mentioned that longer rods are likely to bend. What if I would use tan rods?
even so, they will bend. like a real arrow, they are harder to bend than knex rods, yet they bend a lot in the air, i belive that this is because the back part of the arrow is where all the force is being released, and the front part has to keep up with the speed of the back part, so when the back part pulls ahead, the arrow bends, and when the front matches that speed, the arrow starts to straighten out. haven't you noticed how the longer rods shoot, and they get some distance, and suddenly drop towards the ground? well that's why. so to answer your question, the tans rods will get farther than the red ones of the same length but it will still not get as much distance as a yellow rod.
But, if you used stabalising fins or used another way to launch it so that the initial force would be at the front, this wouldn't happen, right?
correct, because if the front is what is leading the bullet, not the back, then the bullet cannot bend in the air, however, this is only possible for slingshots like sr-v1 where the rubberband is latched onto the FRONT of the bullet. stabalizing fins help, but not if the back is where the force is being released. the sr-v1 is a perfect example of what i am trying to say.
or you can have a yellow rod + red connector together but the red connector is towards the end of the barrel, so it pulls not pushes
but in that case, the red connector is not releaseing the force, the force was released into the yellow rod, so that wouldn't work. the back is still controling the bullet.
oh, the post comment button is different!
umm, ok? little confused with what that is supposed to mean... do you mean the colour change?
yes!
umm.... ok then. thanks for pointing that out? :P so anymore questions you would like me to answer for you?
I found out you are more into the community than i first thought
oooooooooookkk? lol :P
ok just stop everyone is laughing by now
TigerNod (author)  lioneatr5 years ago
Please, this was a serious comment.
razzlekunai5 years ago
No. Red rods and oodammo make better ammo.
TigerNod (author)  razzlekunai5 years ago
I mean do rods bigger then green make better ammo. Red is bigger then green. I don't count oodammo with that: this is about rods.
The Jamalam5 years ago
This made me laugh so hard when i saw the title :P
TigerNod (author)  The Jamalam5 years ago
Why? I do not understand. Is it a sexual reference?
Yes it is.
haha! i just got it! man that is totally hilarious!!!!! right now, im trying not to laugh! (not working) hahaha!!!
osi5 years ago
As logic boy stated, a larger rod has more inertia do to its greater mass, however you need more initial acceleration to get it up to its maximum speed. A small rod would require very little initial acceleration but would loose its energy faster do to its lower mass.
TigerNod (author)  osi5 years ago
Ok, I select this as best answer.
The larger rods have a greater mass and therefore more inertia. also they are less affected by wind as they have more mass. green rods may fly faster but they dont hit as hard or fly as far.
TigerNod (author)  Fred the Penguin5 years ago
In theory, a faster rod would be harder to avoid, but with more range, I think grey suits my needs.
exactly why most large weapons like snipers or assault rifles use yellow rods or larger