POWERFIN FEATURES:

The following paragraphs will provide details for the features listed below.

PROFESSIONALLY DESIGNED BLADE PLANFORMS

There are a few companies out there trying to make one blade planform work on everything from a 28Hp to a 100Hp engine by trimming the diameter, varying the pitch, or adding blades. Their propellers may be efficient on some applications but cannot be efficient on all of them. Each type of application requires a specific design to maximize efficiency. Powerfin Inc. has commissioned the services of professional aerodynamic engineers in order to produce a number of specific designs. For instance, a powered parachute requires a very specific design to maximize static thrust. The other flight configurations of climb and cruise are basically irrelevant for these types of vehicles. We have a propeller specifically designed for these types of vehicles, which produces 398 pounds of static thrust on a 65Hp engine with a 2.59 reduction ratio. That's about 50 pounds more than the other manufacturers have produced. There won't always be that much difference between the competition's propellers and ours but there is always some difference due to the professional engineering of specific, targeted designs.

FULLY PITCH ADJUSTABLE

The above paragraph highlights the reasons why it is necessary to have a specific design for your application. Even when that is done however, there is usually some imperfection to the design. In other words, if you were to order a fixed pitch wood prop and the person making it was the best in the business, the variables that must be accounted for are so numerous and uncontrollable that rarely can the prop maker make a propeller absolutely perfect for your application. This is especially true in the ultralight category where small two-stroke engines can vary widely in horsepower and torque from engine to engine of the same make and model. The result of these variables is frequently a propeller that loads your engine slightly too much or too little and prevents you from running your engine exactly where you need to in order to use all available horsepower. With a fixed pitch prop you are stuck with what you have. With a fully pitch adjustable prop you can set the blades such that you load your engine to whatever RPM you choose. This also gives you the luxury of choosing whether you'd like to have better cruise or climb performance - something you can't do with a fixed pitch propeller. All Powerfin propellers are fully pitch adjustable.

SIMPLE ASSEMBLY WITH THE APEX SPEED SET HUB

Assembling the Powerfin propeller and setting the pitch is no more difficult than putting the blades in the hub halves, putting the hardware in, selecting a proper feeler thickness (we give you a chart for that), and turning the blade solidly against the feelers. We call this our Speed Set (U.S. patent pending) hub. The objective of our design was to eliminate ANY requirement of finesse or feel when setting the pitch. We did it and we can proudly boast that a ham fisted guy can do this in high winds with his eyes closed - and get it within a half of a degree on the first try! Another feature of the hubs that simplifies it is the fact that it takes only a single wrench to do the job. There is no fumbling or fooling around with backing nuts in this design. One wrench and socket does the whole thing. The final feature worth noting about this hub is that you cannot set the pitch at all if the blades are backwards in the hub. This design precludes the possibility of many errors that could be committed in the course of assembling and mounting a propeller. See pictures of the assembly process here.

NEW 2, 3, 4, &5 BLADE APEX HUB - HIGHEST QUALITY PROPELLER HUB AVAILABLE

The new Apex series, fully ground adjustable hubs are the finest crafted hubs available to the ultralight and experimental market. Made in-house on our new Haas VF4 CNC vertical milling station, these hubs offer features that are unavailable on other hubs. By nature of the fact that we own the machine, we can take the time to pack features into these hubs that we couldn’t afford to buy from an outside vendor. They are highly sculpted solid 6061-T6 aluminum and are made to the finest CNC machining tolerances in the industry. In fact, we specifically designed the machining process to insure a perfectly balanced prop hub. The hubs are anodized to a luxurious black finish you will be proud to display. It takes longer to make Apex hubs, it’s true, but there is no comparison between these hubs and any other offered by our competition.

The multi-blade configurations offered with the new Apex hubs allow us to take advantage of the large reduction ratios offered by Rotax and Hirth in their gearboxes. Also, more horsepower can be loaded into more blades so this may be a solution to some applications that have limited room to turn a propeller. See pictures of the Apex series hubs here.

SUPERIOR COMPOSITE STRUCTURE

The goal of those who design aerospace parts with composite materials is to create a part that approximates metal in strength yet remains very light. In order to accomplish this the optimal fiber to resin ratio of the chosen fiber must be controlled so that the published mechanical properties of that fiber can be relied upon. If this ratio isn’t controlled, the strength, weight, and consistency of the part will be suspect. High-tech aerospace companies normally use pre-preg composite materials to help them do this. Pre-preg means that the fiber manufacturer lays the resin into the fiber mechanically. The fiber to resin ratio is controlled perfectly. It comes to the end user frozen so it will not cure. The end user will cut the pre-preg into specific shapes and lay those shapes into the mold cavity. With pressure and heat the molds are cured to produce wonderfully uniform parts. The result of this level of control is to eliminate the use of more material than is necessary to do the job and therefore, forego useless weight. Fiber placement is perfectly controlled. Fiber to resin ratio is perfectly controlled. Void content is perfectly controlled. Weight and strength is perfectly controlled. Powerfin Inc. is the FIRST and ONLY propeller manufacturer in the USA to make propellers for ultralight and small experimental aircraft using pre-preg materials and pressure in the molding process. All the others use cruder techniques that result in blades that are weaker or heavier.

Another aspect to our design is the high compressive strength foam core used in our structure. The only purpose the inside of any bending structure serves is to keep the two outside layers apart under load. Aerospace engineers have found that high compressive strength foam can do that job without adding much weight to the structure. One added benefit to using foam in a high vibration environment is that it is an excellent dampener. Powerfin propellers use high compressive strength foam as a core material. This is one of the reasons Powerfin propellers have such smooth operation and why they have such low weight and inertial mass.

VERY LOW INERTIAL MASS

Few things are as underrated and misunderstood about small aircraft propellers than moment of inertia. Low moment of inertia is critical to the safe, smooth, and long lasting operation of your two-stroke engine and reduction unit. Inertia, by definition, is the reluctance of a mass to accept changes in velocity. When your engine is idling the pulse tries to accelerate the prop and the compression tries to decelerate it. High inertial loads in this situation help compression and hinder the stroke causing many engines to idle poorly. Most people fiddling with timing and fuel mixture trying to solve this problem never suspect high moment of inertia to be the culprit. High moment of inertia in a propeller is also bad because the propeller becomes a more effective gyroscope with a higher tendency to remain fixed in space. This has three effects. 1. It puts more pressure on the bearings in the final stages of your reduction unit as you turn your airplane in flight. 2. It causes more adverse turning tendencies due to gyroscopic precession. 3. It reflects vibration that can be felt by the pilot instead of absorbing and dissipating it. Low moment of inertia in a propeller also means faster access to your available horsepower, reducing spool-up time when you hit the throttle. In the right flying situation a Powerfin propeller can pull you out of a jam faster than a propeller with high inertia.

Rotax has set a limit for how much inertial mass is allowable on the A/B-box and C/E-box. On the A/B-box they want propellers with no more than 3,000 kg/cm2. A 72" – 3-blade Ivoprop ultralight propeller is about 4,500 kg/cm2. The same Warp Drive is over 10,000 kg/cm2. Powerfin propellers are 2,500 kg/cm2 for a big three-blade model and 1,800 kg/cm2 for a two- blade model. Powerfin Inc. is the only U.S. manufacturer to have addressed this issue and met the challenge of designing a very durable, low inertia propeller for the Rotax gearboxes.

BEAUTIFUL HIGH GLOSS FINISH

The blade finish of Powerfin propellers rivals anything this industry has yet produced. There are UV inhibitors mixed into the materials that we use so your propeller will stay shiny for years. We also include instructions for maintaining the finish against deterioration. Every Powerfin blade leaves the factory with urethane leading edge tape applied to it. This is standard equipment and is easily replaceable if it becomes worn. The tapes are available from Powerfin or other aircraft suppliers at a very reasonable cost. See pictures of Powerfin blades here.

TOTALLY INTERCHANGEABLE BLADES

Every aspect of Powerfin propellers exemplifies a precision made product. The use of pre-preg carbon fiber and e-glass results in blades that are all molded to within 5 grams total weight of each other. Due to this extremely tight process, Powerfin can easily match the balance of your broken blade by referencing a number scribed onto each blade. The customer can order replacement blades simply by reference to this number. This eliminates a great deal of hassle for the customer who already has enough to be angry about.

EXCEPTIONAL WARRANTY

We are proud of the product we produce at Powerfin and we have structured our warranty to prove that. If you purchase a Powerfin propeller and are not satisfied with it for ANY reason, please return it in good condition to Powerfin Inc. within 90 days of purchase and we will refund your full payment. We also offer a two-year warranty for free replacement of any part containing a defect. Our goal is to never have a customer who is not happy with his propeller. We can make mistakes at times and recommend the wrong propeller diameter or style but we will never be complacent in the face of a dissatisfied customer. Please let us know when you have any concern with what you have purchased from Powerfin Inc. so we can make it right.

WHEN ORDERING A POWERFIN PROPELLER:

Recreational Power Engineering (a distributor for Powerfin) will accept Visa, Discover and MasterCard. Personal checks, cashier’s checks, and money orders will be accepted for pre-paid orders. Free shipping anywhere within the continental US. When ordering, please have the following information available.

CURRENTLY IN USE ON:

Hirth - Rotax - HKS - MZ - Cayuna - 2si - Verner - Subaru - Kawasaki - BMW - VW - many others