Aluminum VS. Wood Propellers Continued...
The first type of propeller that I will talk about is the aluminum propeller. . The aluminum propeller design was used on the first airplane the Wright brothers flew. Although there airfoils were off which made for a short flight Modern propellers are fabricated from high-strength, heat-treated, aluminum alloy by forging a single bar of aluminum alloy to the required shape. Metal propellers are now extensively used in the construction of propellers for all type of aircraft. The general appearance of the metal propeller is similar to the wood propeller, except that the sections are generally thinner. They are heavier though and more prone to damage by the vibrations.
The wood propeller is still one of the better material choices for a propeller. Wood is the lightest material, even lighter than carbon in some cases depending on the lay-up of the composite propeller and the type of wood used. Wood propellers seem to allow the engine to accelerate at a faster rate than some heavier propeller. Attention to the grain type and uniformity of the grain is important when selecting a wood propeller. Most if not all wood propeller manufacturers use only the best wood, usually hard maple, but a good tight straight grain that is uniform on both blades will help when it comes to balancing. The wood propeller is the most vulnerable to distortion. It likes to bend and twist depending on the grain and built in stresses. A wood propeller can be machined accurate and distort when material is removed from the blank in the machining process. This is why the larger blades are more likely to be laminated for several layers of wood. One of the problems with wood propellers is the variety of different pitches in the same make and model of propeller. So it is possible for one propellers pitch to be more than two inches of another of the same kind. This will cause the greater pitch propeller to accelerate faster. Another difference between different propellers is the airfoil cross sections at the tip. One blade can have a thicker air foiled tip while another is more flat. If the blade is thick enough, some wood can be taken from the face of the blade at the trailing edge to remove some of the pitch. This difference in seemly similar propellers is a downfall to wood propellers. You can crawl into the same two planes with the “same” type of wooden propellers, and they will perform very differently. The difference comes from the fact that you can make your own propellers and have them either not laminated or laminated. But the advantage is that they are generally cheaper.
In my opinion I believe wood propellers are far superior to their aluminum counterparts. Wood propellers have a few advantages when compared to the aluminum variety. Some of these advantages include cost, weight, and fatigue. One of the first advantages of wood propellers deals with vibrations. Your engine and aircraft will produce vibrations during flight. Aluminum propellers will become damaged internally when subjected to these vibrations over time. This will also put a lot more strain on the engine. Wood propellers will simply dampen these vibrations and won't be affected by them. The next advantage of wood propellers is their cost. Aluminum propellers usually cost a lot more because of how they have to be manufactured. They have to be cast, grinded, and polished. Wood propellers are much easier to make since they just have to be carved. Therefore, they will cost less money. These propellers can also be used with more power engines. Another advantage of wood propellers has to do with R.P.M.s. These propellers can be used on engines that can go up to 6,000 revolutions per minute. Aluminum propellers aren't safe to use with engines that go that fast. They would be destroyed by the vibration and probably kill the engine from stress. Therefore, aircraft that use wood propellers can usually go faster than those fitted with aluminum designs. Propellers that are made from aluminum can form cracks and fail due to metal fatigue when being run at high R.P.M.s for long periods of time. It is common for them to suffer from broken hubs or blade tips. Wood propellers aren't as susceptible to fatigue, so they will never fail. The final advantage of wood propellers is weight. Aluminum propellers weigh considerably more than their wooden cousins. A typical propeller made from aluminum with an 80 inch diameter will weight about 90 pounds. Wood propellers that have an 80 inch diameter will only weigh about 60 pounds. These reasons are why I like wood propellers are far better. So for any airplane I think that a wood propeller would be major advantage.
In conclusion, these two propellers, wood and aluminum, are each very different and have their pros and cons. If I were to buy my own plane though I think that I would want to get a wooden propeller on my plane because of all the advantages.
The wood propeller is still one of the better material choices for a propeller. Wood is the lightest material, even lighter than carbon in some cases depending on the lay-up of the composite propeller and the type of wood used. Wood propellers seem to allow the engine to accelerate at a faster rate than some heavier propeller. Attention to the grain type and uniformity of the grain is important when selecting a wood propeller. Most if not all wood propeller manufacturers use only the best wood, usually hard maple, but a good tight straight grain that is uniform on both blades will help when it comes to balancing. The wood propeller is the most vulnerable to distortion. It likes to bend and twist depending on the grain and built in stresses. A wood propeller can be machined accurate and distort when material is removed from the blank in the machining process. This is why the larger blades are more likely to be laminated for several layers of wood. One of the problems with wood propellers is the variety of different pitches in the same make and model of propeller. So it is possible for one propellers pitch to be more than two inches of another of the same kind. This will cause the greater pitch propeller to accelerate faster. Another difference between different propellers is the airfoil cross sections at the tip. One blade can have a thicker air foiled tip while another is more flat. If the blade is thick enough, some wood can be taken from the face of the blade at the trailing edge to remove some of the pitch. This difference in seemly similar propellers is a downfall to wood propellers. You can crawl into the same two planes with the “same” type of wooden propellers, and they will perform very differently. The difference comes from the fact that you can make your own propellers and have them either not laminated or laminated. But the advantage is that they are generally cheaper.
In my opinion I believe wood propellers are far superior to their aluminum counterparts. Wood propellers have a few advantages when compared to the aluminum variety. Some of these advantages include cost, weight, and fatigue. One of the first advantages of wood propellers deals with vibrations. Your engine and aircraft will produce vibrations during flight. Aluminum propellers will become damaged internally when subjected to these vibrations over time. This will also put a lot more strain on the engine. Wood propellers will simply dampen these vibrations and won't be affected by them. The next advantage of wood propellers is their cost. Aluminum propellers usually cost a lot more because of how they have to be manufactured. They have to be cast, grinded, and polished. Wood propellers are much easier to make since they just have to be carved. Therefore, they will cost less money. These propellers can also be used with more power engines. Another advantage of wood propellers has to do with R.P.M.s. These propellers can be used on engines that can go up to 6,000 revolutions per minute. Aluminum propellers aren't safe to use with engines that go that fast. They would be destroyed by the vibration and probably kill the engine from stress. Therefore, aircraft that use wood propellers can usually go faster than those fitted with aluminum designs. Propellers that are made from aluminum can form cracks and fail due to metal fatigue when being run at high R.P.M.s for long periods of time. It is common for them to suffer from broken hubs or blade tips. Wood propellers aren't as susceptible to fatigue, so they will never fail. The final advantage of wood propellers is weight. Aluminum propellers weigh considerably more than their wooden cousins. A typical propeller made from aluminum with an 80 inch diameter will weight about 90 pounds. Wood propellers that have an 80 inch diameter will only weigh about 60 pounds. These reasons are why I like wood propellers are far better. So for any airplane I think that a wood propeller would be major advantage.
In conclusion, these two propellers, wood and aluminum, are each very different and have their pros and cons. If I were to buy my own plane though I think that I would want to get a wooden propeller on my plane because of all the advantages.