What are the Pros and Cons of Aluminum Propellers?

Lori Kilchermann

Aluminum propellers are lightweight and relatively inexpensive. This makes them good candidates for installation on both aircraft and boats. There are, however, both pros and cons to installing aluminum propellers that should be examined thoroughly prior to committing to a purchase. The weight reduction over both steel and wood allows an engine to come up to speed much faster when using aluminum propellers. The soft composition of the aluminum propellers can, however, make them prone to chipping and bending.

Aluminum propellers are lightweight and generally cheap.
Aluminum propellers are lightweight and generally cheap.

Placing a lighter propeller on an airplane may seem insignificant at first glance. After examining the benefits of aluminum propellers, however, it might seem like a rather wise investment of time and money. By installing aluminum propellers on aircraft they are able to build speed much faster due to the reduction in rotating mass as compared to a wooden propeller. This equates to shorter takeoffs and increased rates of climb.

Aluminum is softer than stainless steel, which puts boaters at a disadvantage.
Aluminum is softer than stainless steel, which puts boaters at a disadvantage.

In a boat, the same principles apply to the lightweight propeller. By having less weight to turn, the boat is able to accelerate much quicker. This allows the boat to come up on plane in a much shorter distance as well as increasing the speed of the boat as measured over a short distance. In case of accidental contact with a rock or submerged object, the soft alloy is often bent and not broken. This allows the propeller to be easily returned to its original shape and pitch at an experienced propeller repair shop.

There are also downsides to using aluminum propellers. In aircraft, the aluminum propeller is prone to becoming lightly pitted by sand and debris. The soft alloy is also prone to corrosion. This all means that extra maintenance will be required as compared to using a wooden or composite propeller. Expense is typically a great concern with most buyers, and the aluminum propellers are more costly than their wooden and composite counterparts.

When comparing boat propellers, aluminum is inferior to stainless steel when all out speed is an issue. The aluminum propellers are thicker than the stainless steel versions and do not have as much cup engineered into the blades. The thinner stainless steel propellers are usually faster at top end speeds and often are better balanced. The soft aluminum is better for slow speed bumps, but typically breaks beyond repair when striking an object at high speed. This can often lead to excessive engine revs and consequential engine damage as well.

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