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Discussion Starter #1 (Edited)
So, with numerous posts about Apex and Flatline barrels out there (and whatever other backspin barrel might exist), I decided to help people understand how they work and if they would still like to buy a backspin type barrel system.

Bernoulli's Principal and the Coanda Effect are the simple physics that are used in all backspin type barrels.
The Flatline barrel, Apex barrels, and airplane wings all work off of these two principals

Bernoulli's Principle basically states "Faster Fluids Less Pressure"
Air is classified as a fluid because of the way it acts

The Coanda Effect says that a fluid will follow the shape of an object that it passes over.
Place the edge of a cup under a sink and the water doesn't just fall right off the edge, it follows the curve of the cup for a while.

Now that we got a basic understanding of some physics, we can move on to how the Flatline and Apex barrels work and keep paintballs in the air at slower speeds with the help of airplane technology!

Airplanes create life though air pressure on their wings.
An airplane wing is curved on the top and straight on the bottom. Air travels along both the straight side and the curved side thanks to the Coanda Effect.
Since the straight and curved side of the wing both start and end at the same point as the other half, there is more distance for the air to cover on the top of the wing than on the bottom of the wing.
This leads to the air having to travel faster over the top of the wing relative to the bottom of the wing so that the air on the top of the wing can meet the air at the bottom of the wing at the same time.
Bernoulli says that faster fluids creadte less pressure, and that equates to more pressure on the bottom of the wing relative to the pressure on the top of the wing.
Lift is created!

Now for paintballs!

The secret to the Flatline Barrel and the Apex Barrel is backspin!
Backspin creates uneven airflow across the paintball relative to the axis which it is spinning (let's just say the paintball is spinning on a horizontal axis relative to the shooting surface).
The air on the bottom of a paintball spinning backwards will encounter friction (air going one way, paintball spinning in the opposite way), while the air encountering the top of the paintball will encounter less or no friction (air and paintball spinning in the same way.
Air will move faster over the top of the paintball relative to the bottom of the paintball.
Bernoulli says that faster fluids create less pressure, and that equates to more pressure on the bottom of the paintball relative to the pressure on the top of the paintball.
Lift is created!
Now paintballs can have a flatter trajectory for longer at slower speeds!

This is how all types of backspin barrels work!

Now that the paintball has slowed down in flight, outside forces like wind and debris can change the flight pattern of the paintball because the paintball has less inertia.

Inertia is the resistance of mass to a change in its state of motion. The slower a paintball goes, the less inertia it will have.

Now lets say the axis that the paintball spins on is knocked off alignment with true vertical because of a puff of wind or it hitting foliage. You not have a nonvertical pressure on the paintball causing it to swing left and right since there's no need to compensate for as much gravity.

So in conclusion:

Q: Do Back-Spin Barrels let you shoot farther than a normal barrel?
A: Yes, but at the extended range and speed of the paintball, you may not get any breaks on people, which negates the added range

Q: Are they more accurate than a regular barrel?
A: No, they are just as accurate as long as no outside forces act on the paintball while it's in flight (which will almost never happen)

Q: Do they shoot straighter?
A: They do send the paintball on a flatter trajectory pattern, so you won't have to arc your shots as much

Q: Are Back-Spin barrels worth the money?
A: That depends on what you;re looking for and what you want your barrel to do

Q: If I had to get a backspin barrel, which is better, the Flatline Barrel or the Apex Barrel?
A: The Apex, hands down. It's fully adjustable for amount of spin imparted on the paintball and angle of spin it puts o nthe paintball, the Flatline does not have that kind of adjustability

So I hope this will help people make their own informed choice on wether they should get a backspin barrel or not and answer any questions people might have on them!


Retired, proud dad
702 Posts
the real advantage is not to shoot farther, but the paintball fly straighter before the final drop. So you're not forced to shoot with an angle.

However I agree with AZN : if you plan to shoot farther, you'll be disappointed because the extra range is useless exept if you're lucky and get hard touch, like a mask. IMO they are not great investment.
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