Manufacturing Process

The Manufacturing Process of an Propeller

Ever wondered how a high-quality wood propeller such as the P-Prop is made? Well, if you have, here is a step-by-step look at what is involved in this highly specialized process.

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Step 1 – Wood Selection

Wood-Select-01.

The P-Prop is manufactured from first grade hand selected Eucalyptus Saligna timber, purchased direct from the sawmill. The timber is kiln dried for 3 weeks until the moisture content stabilizes at 8%. The timber is then stacked in a specific pattern under complete protective cover to avoid any potential interference by weather elements. This ensures absolute stability against warping, twisting and potential bow bending before the pieces are selected for processing.

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Wood-Select-02.

All wood is inspected for straightness of grain with a slant ratio of 1mm to 30mm or higher. The timber grain used in P PROPELLERS has a typical slant ratio of 2000 to 1!! Timber selected has zero knots, whorls or cross grain. Every piece is meticulously weighed, precisely balanced and sorted by density of grain before the lamination process even begins.

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Wood-Select-03.

The pieces selected for a propeller “blank” are cut and planed and meticulously weighed and balanced once again. The laminates are stacked by a precise and careful method to counter any abnormal weight and density distribution before the carving process begins.

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Step 2 – The Press

 

Step 2-01.

The laminates are stacked by a precise and careful method to counter any abnormal weight and density distribution before the laminating process begins.

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Step 2-02.

The propeller “blank” is glued together in a precision made press. Pressure is maintained at a specific level to prohibit joint starvation as per specification of the adhesive manufacturer.

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Step 2-03.

The combination of intense pressure and the powerful Phenol-Formaldehyde adhesive ensures that the adhesive penetrates the timber grain substrate to a depth of approx 1mm. This guarantees a 100% cohesive protection against delaminating tendencies.

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Step 2-04.

The laminates are kept under pressed for 48-72 hours until the adhesive has reached optimum chemical curing time.

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Step 3 – Curing

 Step-1-3 Curing.

Once optimal cure characteristics are reached the propeller “blanks” are removed from the press and stored in a controlled environment beyond the reach of the elements until retrieved to be carved by CNC.

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Step 4 – Shaping

 

Shaping-01A “blank” is retrieved from the protected storage area and enters a process where 60% to 70% of the mass of the timber is cut away in preparation for the final carving process.

CNC cut templates, generated by a 3d NURBS program, to an accuracy of 0.3mm is used to remove the excess timber from the propeller “blank”.

Once the excess material is removed the block is now processed by the CNC machine to the correct silhouette and thickness to accommodate a pitch and airfoil accuracy of 70% of the length of the propeller.

Various cutting bits are selected to complete the process. The CNC has multiple cutting heads to cut duplicates of propellers at the same time if batches of propellers are ordered.

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Step 5 – Carbon Fibre

 

Carbon Fibre-01.

After the propeller has been carved the pitch angles are meticulously checked by digital instruments to an absolute tolerance of 0.2˚ and then compared to the 3d NURBS theoretical design pitch angles.

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Step 6 – Poly-urethane

  

Step 6-01.

P Prop pioneered the use of elastomer polyurthane as a means of protecting propeller leading edges since 1983. The leading edge consists of a two part elastomer casting material imported from Germany.

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This material is extremely resistant to the elements such as rain, hail, small pebbles, gravel found on runways, grass, small pieces of wire etc.abrasion and so forms the best protection the P-Prop has against objects entering the prop disc.

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Step 6-02.

Depicted is a test propeller which was turned at 3300 rpm. A front end loader (JCB) slowly tipped 500kilograms of river sand (average grain size of 0.2mm up to 4mm) into the arc of the propeller. The end result was that 40% of the propeller was eroded. However only 3% of the urethane leading material was removed.

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Step 7 – Finishing

 

Experimental-Aircraft.

The prop is lightly sanded and finished by 2k paint protection. The paint is exactly the same brand and quality used on the Boeing and Airbus carriers.

 

One more P-Prop is ready to fly… Well… nearly ready…

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Step 8 – Final Check

 

Step 8-01.

The finished propeller has to pass an after manufacturing 7 point inspection equal to or in most cases exceeding the highest standards set by any propeller manufacturer on earth.

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Step 9 – Markings

Last step markings.

Left: Manufacturer PPROP

        Length 60inches

        Pitch    42 inches

Right: Serial number N3565

Materials: FEG6  (Flexi edge Glass fabric)