Unusual notches on very old boomerang

[Roland_M]

Originally Posted by Battara

Could they be for aerodynamic speed and lift?

I dont think so, because the notches are on the trailing edge, not on the leading edge.

I simply think, the notches are either a kind of simple decoration or (better idea) made for more grip during the throw.


Roland

[chiefheadknocker]

Originally Posted by Roland_M

I dont think so, because the notches are on the trailing edge, not on the leading edge.

I simply think, the notches are either a kind of simple decoration or (better idea) made for more grip during the throw.


Roland

yes I agree , the notches are on the trailing edge

[Ian]

When an object is spinning, I'm not sure one can say that there is a consistent leading and trailing edge.

As a kid growing up in Australia, I played with boomerangs and knew a few aboriginal kids that I would see on summer holidays along the eastern Victorian coast. The manner of throwing a boomerang is with the concave edge forward, at least that is how the aboriginals throw them. The fingers therefore grip one end of the concave side. The notches on this example are on the end of the convex side, and therefore would impinge on the palm of the hand--that could be uncomfortable and would be of no advantage in gripping the boomerang. This manner of throwing the boomerang is used for the ones that return to the thrower. I'm not sure that the same technique was used for hunting boomerang, which could be the opposite. The boomerang shown here is not markedly curved, like the returning examples, and the straighter ones are usually described as "hunting" boomerangs that were often thrown more vertically than the returning type, which are thrown at an angle of about 45 degrees to the ground.

I don't have an answer for what the notches represent, but they probably were not helpful in gripping the boomerang to throw it. Perhaps our resident Aussie, Alan Maisey, may have a better idea what they are for.

Ian.

[Roland_M]

Originally Posted by Ian

When an object is spinning, I'm not sure one can say that there is a consistent leading and trailing edge.

I just compared the boomerang to a one bladed fan with an axial impeller. Now I`m unsure.

From the aerodynamic point of view, the notches will not have any postive effect. The boomerang is spinning and flying too slow, for a measurable result (imho).


On an axial or radial impeller such notches can reduce the turbulences and increase the degree of efficiency of the impeller. No one should laugh about this, I have a patent for notches on impellers.

So the idea of the aerodynamic improvement is really good from the technical point of view (state of the art for fans and compressors)


Roland

[Ian]

Originally Posted by Roland_M

I just compared the boomerang to a one bladed fan with an axial impeller. Now I`m unsure.

...

Roland

Hi Roland:

Yes, I think a rotating projectile is likely different from a stationary fan. Both the axial and linear speeds are probably important, but my college physics is a long time ago.

Ian.

[A. G. Maisey]

Ian, I'm afraid I cannot assist with any specialist knowledge on boomerangs.

I do live in an area that has a very strong Koori presence, and a living Koori culture, I have neighbours who identify as Koori, I have friends who are Koori, many years ago (notably when I still had some influence in public service circles) I was invited to acknowledge my (non-existent) Koori roots.

But I do not have any specialist knowledge of boomerangs. Sorry.

[Ian]

Thanks Alan.