Wednesday, April 18, 2012

Wooden Propeller: The Plans


Its no secret that Ruedi and I are huge aviation fans. Propellers are an icon for the golden age of flight when airplanes were simple and extraordinary. Ordinary men like the Wright Brothers, Manfred von Richthofen, and Charles Lindbergh were catapulted into stardom- the heros of young boys and grown men alike for generations to come. If you know what I'm talking about then this project is for you- bring a pice of aviation history into your home (or man cave) and try your hand at the lost art of propeller carving.



The National Air and Space Museum in Washington DC (and the one at Dulles) is my favorite museum in the world (the National Museum of the USAF and the Imperial War Museum- Duxford are close seconds). I could spend hours upon hours drifting through the exhibits- and I have. I saw the propellers Orville and Wilbur designed and hand carved in the Smithsonian and I thought, well if they could do it, certainly I can with all the modern amenities afforded to me that they had to figure out without Google. (Did you know the Wright brother's prop was only 5% less efficient than props used today? Woah!)

Close by, this little exhibit showed how props were carved from this:


Into functional aviation art:



I found old blueprints at woodenpropeller.com for a multi layered prop like the one pictured above and traced them into AutoCAD to give me a crisp line drawing to scale the prop as large as I needed it. The prop I'll be building is going to be 72 inches in diameter, but the drawings are scalable so you can make the prop small enough for a model airplane if you really wanted to. It may require some manipulation of the PDFs but it can be done. Typical propellers used during and prior to WWI were 8' or longer. As engine speeds increased, the length of the propeller decreased, so post-war props were typically between 6'-8'.

What you'll need
Tools
  • Planer (or have the sawmill do it)
  • Jigsaw/band saw
  • Clamps- lots of them. 6 good ones at a minimum. 
  • Drill press
  • 2" hole saw
  • 5/8" drill bit
  • Drawknife 
  • Spokeshave
  • Chisels (maybe)
I'm going the hand tool route (minus the initial roughing) to try and capture the essence of how these props were originally made. We'll see how long that lasts.

Materials
  • Full scale print outs of the prop sections. Take the drawings to FedEx Office or a similar print shop and have them printed. Get a few copies while you're at it just in case.
  • Lumber (4) 3/8"x8"x96" planks. Make sure the boards are a minimum of 8 in. wide, not just a nominal 8 in. or the design won't fit on four boards. For a layered look like the prop above, chose wood with different shades. I'm thinking about using locally sourced Red Oak and Ash. In the early days of aviation, Mahogany (most likely a carry over from the furniture industry) and Walnut were the most commonly used materials. Towards the middle of WWI,  the use of Oak took over as it was considered to have better properties. Whatever species you choose, hand pick boards that aren't warped or have knots.
  • Wood glue
  • (8) AN5-34 Drilled Bolts (optional) Another option is to pick up regular 5/8"x3.5" bolts and drill the heads with a 1/16th carbide drill bit (not as easy as it sounds).
  • (8) AN310-5 Castle Nuts (optional)
  • .032 Safety wire (optional)

Finishing
  • Sandpaper 100, 150, 220 grit, and dry/wet 400 grit
  • Orange Shellac from ColorFX to make the wood appear aged (optional)
  • Wood Sealer
  • Wipe-on, Satin Polyurethane 
  • Finishing details- i.e. manufacturer decals, impression stamps, paint for the tips, metal tip reinforcement. I haven't decided how detailed I want to get on this one. 
Gentlemen: without any further adieu, the free plans for your building pleasure:

blueprint.jpg
blueprint2.jpg (with original dimensions- thanks to Pitor for sending this my way)

PDF files are designed to be scaled to ANSI E-size paper 34x44" to yield a prop 72" in diameter.

This project has been one in my docket for the last year or so. Unfortunately, I'm limited to an outdoor workshop that has a limited season of usage due to the unpleasant weather we get here in Texas. But I think I can squeeze it into my schedule. Stay tuned for the build.



You may also like:
The Essential Toolbox List
The ABC's for Special Forces, Fighter Pilots & Manly Men 

4 comments:

  1. Thanks for posting this. I had the plans printed and just finished making templates of each section out of 3/16" plywood. First prop is going to be mahogany and holly. Don

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    Replies
    1. Great! I'm about half way complete with mine but it already looks great. That material combibation will give you some great contrast. Be sure to send us some pictures of your progress and the finished project. Good luck!

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  2. Thanks for those free plans...on my way to build one :)

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  3. Hi
    That is so cute, I would of never thought of that. I am definitely making me one or maybe a few! LolSanta Barbara Green building

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