What causes a boomerang return?

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In summary: Then why does it precess?The boomerang is not balanced, so there is a torque on it. The aerodynamic force exerted on each blade is not equal, since the blades move through the air with different speeds. (While one blade rotates forward, another rotates backward.)
  • #1
arevolutionist
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What causes a boomerang return?
 
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  • #2
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  • #3
Not only do boomerangs return, but some shapes will fly in a figure 8 pattern, if you don't catch it on the initial return, it will fly by and circle in the opposite direction and return again.
 
  • #4
Yes but what i wonder is whys that the boomerang precess since is a case of balanced gyroscope
 
  • #5
giordano bruno said:
Yes but what i wonder is whys that the boomerang precess since is a case of balanced gyroscope
Because there's a torque on it. The aerodynamic force exerted on each blade is not equal, since the blades move through the air with different speeds. (While one blade rotates forward, another rotates backward.)
 
  • #6
Jeff Reid said:
Not only do boomerangs return, but some shapes will fly in a figure 8 pattern, if you don't catch it on the initial return, it will fly by and circle in the opposite direction and return again.
I though it was actually a cloverleaf i.e. 4 lobes.
 
  • #7
giordano bruno said:
Yes but what i wonder is whys that the boomerang precess since is a case of balanced gyroscope
The point pretty much is that the thing isn't balanced. One arm is longer than the other, so the centre of rotation is offset from the radius of the bend.
 
  • #8
But balanced, four-blade boomerangs work too! When I used to be in the entertainment business (teaching in grad school :cool: ), I would make simple boomerangs out of cardboard and wing them around the auditorium.
 
  • #9
Well... yeah... but you're kinda weird. :tongue:
 
  • #10
Ignoring gravity, it's a natural tendendcy of anything that's moving through a viscous fluid (air, or water, or whatever) to either move in a circle (or a straight line, which is , really, a degenerate circle.)

A boomerang is essentially a wing - something that generates a lot of acceleration while going through the air so that it curves more.
 
  • #11
The Wiki article covers the physics pretty nicely.
 
  • #12
The wiki doenst talk too much on the physics of it

Intuitivile you may consider than when it is spinned around its center of gravity there's more mass on one side of the boomerang than in the other but this is false by definition of center of gravity

On the other hand i had a boomerang which was regular not with wind shape and still worked

So my question is if precession only happens only on unbalance gyros how comes it appears in a boomerang that is a balanced one being the COG and axe in the same point
 
  • #13
giordano bruno said:
So my question is if precession only happens only on unbalance gyros how comes it appears in a boomerang that is a balanced one being the COG and axe in the same point
I answered that in post #5--there's a torque on the boomerang! (By "unbalanced" gyro I assume you mean a gyro with an unbalanced torque acting on it--that's what causes precession.)
 
  • #14
giordano bruno said:
The wiki doenst talk too much on the physics of it

Intuitivile you may consider than when it is spinned around its center of gravity there's more mass on one side of the boomerang than in the other but this is false by definition of center of gravity

On the other hand i had a boomerang which was regular not with wind shape and still worked

So my question is if precession only happens only on unbalance gyros how comes it appears in a boomerang that is a balanced one being the COG and axe in the same point

You have WAY too many things relying on your faulty "intuition" here.

Please read the link given by Danger in this thread. Scroll ALL THE WAY DOWN to the bottom of the page where are is a series of very extensive "intiutive" explanation about the dynamics of a boomerang. If you want a quantitative explanation and derivation, then you either need to sit down and work out the physics of the system, or pick up physics papers/books, and then tell us where you got stuck.

http://pass.maths.org.uk/issue7/features/boomerangs/2pdf/index-gifd.html/op.pdf

Zz.
 
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  • #15
Danger said:
The point pretty much is that the thing isn't balanced. One arm is longer than the other, so the centre of rotation is offset from the radius of the bend.

but that center of rotation will coincide with the center of mass

Any object spinned unless forced to do otherwise will have the center of rotation in the center of mass

Therefore the force of gravity, second force in the couple is exerted exactly on the spinning axe with which there's no arm for the couple

Then why does it precess?

A posible answer would be that the superior wing gets faster air than the bottom one but this doesn't work with a boomerang that has no wing shape like the one i just build of hard paper which works as well
 
  • #16
i think the reason why the boomerang precesses is the tendence of masses to spin on preferred axes

if you spin a hollow ball rimmed with plastiline on the shape of a boomerang and spin it on the short axe it will end up spinning on the long axe, just like a football there the second force for the couple
 
  • #17
The fact that it was designed without any real knowledge of aerodynamics, or mechanics is really quite amazing.
 

1. What is the principle behind a boomerang's return?

The principle behind a boomerang's return is known as the Bernoulli's principle. This principle states that when air flows over a curved surface, there is a difference in air pressure on either side of the curve. This difference in air pressure creates lift, causing the boomerang to curve and return to its starting point.

2. Why do some boomerangs return and others do not?

The shape and design of a boomerang play a crucial role in its ability to return. A boomerang must have a curved airfoil shape, with one side being convex and the other being concave. This shape creates the necessary difference in air pressure for the boomerang to return.

3. What factors affect a boomerang's return?

The shape, size, weight, and aerodynamics of a boomerang can all affect its return. Wind speed and direction also play a significant role. A boomerang may not return if thrown too hard or at the wrong angle, as this can disrupt the airflow and prevent the necessary lift from occurring.

4. Can any object be made into a boomerang?

No, not all objects can be made into a boomerang. As mentioned earlier, a boomerang must have a specific curved airfoil shape to create lift and return. Additionally, the weight and balance of the object must be carefully considered to ensure a successful return.

5. How did ancient civilizations figure out how to make boomerangs return?

It is believed that ancient civilizations observed birds and their ability to fly and return to their starting point. They then experimented with different shapes and designs until they discovered the curved airfoil shape necessary for a boomerang's return.

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