So… Have I finally lost my marbles…?
I got the material for my dream project today.
A full scale replica of the propeller used on the Fokker Dr.I, made famous by the ‘Red Baron’, Manfred Von Richthofen, during WWI.
I have got the drawings from Achim Engels, a gentleman who built several WWI aircraft, from scratch.
The drawings have been redrawn in CAD software and printed in full scale. Each of the seven layers (4 walnut and 3 birch) will be cut according to the profile, thus minimizing the work needed to shape the propeller.
Straight cuts, to facilitate clamping when glueing.
And then I will go easy with hand tools only! Don’t want to risk taking too much off with a power tool.
Wood is wonderful! The delicious scent of the walnut hit me like a sledgehammer when I opened the shrinkwrap plastic, surrounding it. I had a carpenter select the wood and plane it for me, as I don’t have tools for that.
The laminates are 20 mm thick.
The widest part of each laminate is the hub, which is 210 mm in diameter. Standard plank width is 150 mm or 250 mm. The price for dried, knot free 250 mm planks is astronomous. The carpenter suggested using 150 mm planks and glue extensions around the middle. That would save me 30-40% on the cost, including the workmanship of the carpenter.
I asked him how he would go about the glueing of the extensions. Would he plane the planks first, and then glue them, or glue first and then plane…?
Neither, or both. He planed the planks to 22 mm, to facilitate matching of the wood fibers…! He then glued them and planed the last 2 mm.
The outer walnut laminate is single piece. I doubt anyone will be able to spot the extension joints.
The carpenter, whom I bought the material from, suggested glueing extension around the hub, to save money.
Yesterday I learned that they often did this when making real propellers during WWI as well! I had no idea when the carpenter suggested it…
Thinking about it, extensions around the hub makes perfect sense. The rotational forces are relatively small, and the propeller axis hub clamps it together.
YES! Another fun project from Troll! This is epic and will make the ultimate wall décor. All that sanding will keep you warm in the fall. Fall starts next week in Sweden, Yes?
BTW, I will be in Uppsala next week. Where is my jacket?
I guess you call people from Uppsala “snow birds”. That’s what we call Americans from the north who move to Florida. I am looking forward to seeing this prop.
This is a very and most rewarding activity with building wooden propellers-replicas of the early 1900.
I’ve made five British (Sopwith Camel) and German ( mainly Fokker D VII) for decoration and all look marvelous. The real problem is to obtain the original drawings. Since propellers of many dimensions are a commercial item sold via Internet no-one is willing to grant the scaled drawings and the DIY activist. Obtaining the wood planks is another difficulty and the many many clamps necessary for
gluing the planks cost a fortune.
Your work looks wonderful and the photos are so beautiful and most descriptive.Zooming and …scanning on them I have cleared some doubts in mind.
I myself tried to obtain the original drawing through Mr. Achim Engels (Fokker team) but I didn’t success. I wonder if I could ask for the Fokker Axial air-screw drawings. It would be greatly appreciated and viewed with great gratitude. Keep-up this excellent work. Thanks for the hospitality.
Thank you for your interest in this project!
I’m sorry, but I don’t feel comfortable releasing Engels drawings since it’s his copyrighted material.
You can ask him yourself, if you have a facebook account.
I sent him a message via facebook and asked him if I could buy the drawings. He answered me that he doesn’t sell them anymore. But he suggested swapping the drawing for model kits. I agreed, and he sent me the drawing and asked me to send him some kits, equal to my percieved value of the drawing
So I sent four plastic model kits.
I feel I should end this thread with a selfie and proof of the completed project.
I’m sorry I didn’t update it more often, but the blog saw regular updates, at least
That looks great. Dumb question. I see everyone using multiple pieces glued together. Why not just start with one thicker board? Besides getting the really nice layer look, is it necessary?
The original specs of a Axial D262 calls for seven layers of birch and walnut. It’s an early sandwich composite structure where one takes advandtage of the stiffness of the walnut and the flexibility of the birch, while keeping it light.
That said, due to material shortages during the war, there were five layer propellers, some seven layer props with a core layer of oak and even all oak propellers.
Another advantage of the layering technique is that you can make sure there are no imperfections like knots and cracks, in the wood. And as the propeller needs to be both statically and dynamically balanced, you start by checking the balance of each layer, and glue them so every other heavy side is distributed to opposite sides.
When hand carving the propeller, like I did, it’s a lot easier to do when the different layers have the correct shape. It’s «just» a question of removing the steps, so to speak. Some propeller manufacturers, of the time, used copy milling machines. But as far as I know, Axial stuck to hand carving.
