Hopup SHOULD not work

Ok I have been thinking about his and the more I do the more I think there is somthing wrong. If you use perfectly round bbs the back spin you put on it would have no effect becuase the wind would not spin around the bb in stead the bb just pass though the air and drop due to gravity. But as we all know when you agust the hopup it works but in theory it should not unless I am missing somthing. I use an bace ball as an example the tread that is around a bace ball is not just for grip but also for it to disrupt the air to cause a high and low pressure zone causeing the ball to go up or down do to the difrent pressures. If the air is not disruped it can't cause a high and low pressure zone for the bb. Now unless the hopup for a dent of the bb and if your using a perfectly round bb it should not curve up. So anyone know why it works?

I can't remember the theory but it was in my pysics class yast year.

Backspin, you see it on tennis occasionally. Basically it spins 'upward' causing the wind to affect the BB on the Bottom, meaning it rises instead of falling. Gravity still affects it, if you tuned your hop up so it went in a straight line on earth, it would rise almost vertically on the moon.

I'm sure someone has a better explanation, but that's the easiest I could explain it. Good thinking though! But you might want to get a spell checker, I see a lot of mistakes in your post. But I know that brain dead thing that you get, and you end up spelling it wrong. I do it all the time.

sticks

See thats my point the backspin should cause nothing nothing becuase a bbs is to round for it to be able to make a change in pressure. On a tennis the ball is fuffy enoff for it to cause a difrence in air pressure.

Aha, but the wind pushes up on the BB, that's what I was trying to say. The backspin causes the air to 'push' the BB upwards. Pressure should have little to do with it, I'm confused where did pressure come into the equation?

Also, when you apply top spin on a tennis ball it goes downward. The air affects the top of the ball more than the bottom. Can you tell I play tennis much .

I'm 90% sure gyroscopic's have something to do with it, but I'm only in high school. That's a college engineering class.

sticks

Yes, gyroscopics prove what I am trying to say(and when you put a spin on a bb it is pulled in all directions not just up or down, example a gyro scope) and your still not getting one fact that a bb is very round and so there should (like a marble) be no friction to cause the air to go to the bottem (the air moving from the top to bottem or vise- versa would cause pessure but a bb is so smoth so the air would not pass, it would just go pass like a knife though butter). So does anyone here have a degree in pysics or aronatical engenering that could explaine this?
also from http://ezinearticles.com/?Hop-Up-in-Airsoft&id=589601
"A main principle that relates to hop-up is Bernoulli’s Principle. Bernoulli’s Principle states that “in an ideal fluid (includes air), with no work being performed on the fluid, an increase in velocity occurs simultaneously with decrease in pressure or a change in the fluid’s gravitational potential energy.” How does this apply to airsoft? Well, if you read the definition, pressure is inversely proportional to velocity, in that lower pressure equals higher velocity. A spinless pellet will have equal pressure all around it, so the only thing determining its distance is the FPS. The next part is quite complicated, but simply, backspin creates a difference in pressure on opposite sides of the BB, and this difference makes the pellet go further. Another interesting thing is the Magnus effect. Pellets have thin layers of non-moving air on top of them, and when spin is applied, the air pushes off the pellet at a downward angle, and by Newton’s law, then pushes the pellet up, giving it lift. In a non-spinning ball, the air would all go off at the same angle, so there would be no difference in trajectory due to that."

This should not happen due to the fact of very little friction.

But it does.... I see what you meant about unequal pressure now, I was thinking about pressure in relation to differentiating forces in a substance(ie, different depths in the ocean). You were talking about pressure as in force exerted on the BB by the air, which is different.

You are still forgetting the unevenness of a BB on a microscopic level, to do what you are talking about there would need to be no imperfections on the BB. Which there is, even if you look at them with a high powered camera lens you can notice alot of imperfections.

Also you didn't account for the comparative lack of mass of a BB to a tennis ball(or baseball). The BB has plenty of imperfections compared to its relative small weight and size to allow plenty of friction.

Maybe I am wrong about this whole thing though. Thanks for starting this topic, up until I hit this I was having a very stupid day(seriously this was the first educated conversation I have had all day).

Keep these threads coming! Someone else can jump in too you know lol.

sticks

Ok, that was the only thing I could think of is micro scopic inpersections. Still though a glass ball does not (we did that in a lab a year back got it going to 20 rpm). And sticks if you were in my scince class there would be more then enoff questions like about. Lazzers, h-bomb, gravity, quamtm gravity, gama rays, and about a ton more (I think Ill atart that in off topic). And thanks for comferming that unless your not sure but were starting to talk on quntum level and there are like 500 quntum engeiners with major degress and if you have a PhD I wonder how your allowed to talk here unless you turned down that big pay check.

Lol I never said I have a PhD, I don't even have a high school diploma. But you do not necessarily need a Masters or a PhD to understand something.

However I do wish I was in your science class, I have biology and a teacher who is so old school he just learned how to use a computer last year. Meaning we stick to overheads and the crappy curriculum that's provided by the city.

If you really want a sciency answer contact your local university, If you want a good answer I can get you the # to OSU's science department. I'm sure they can give you alot of answers. I'm more of a history guys(more recent stuff).

sticks

Sticks your explanation hit is right on target,

By Putting backspin on the BB you increase the Air Resistance and Pressure on the bottom of the BB, at the same time Reducing it on the top of the BB. When the Backspin balances out the carried energy to the air resistance you get a level flying BB, to much backspin an your BB´s rise, to little the sink.

You don´t need a Microscope to see the Imperfections on a BB, a good Magnifying Glass works well, the better Brands of BB´s actually look a lot like little Golf Balls, even after polishing and wax coating.

Nice Topic.

With the phd think I was wondering what the theorm was and I don't think most people just know that off the top of there head.