Laminated prop in paper

[shrike]

I might have to try going the other direction. I wonder where I could get enough stock to make a 1.8m diametre version......

[Art Deco]

The tiny 1/72 prop shows how small you can go using this technique!

Okay Leif, what are you going to produce next using your "stacked templates"?

Tires? A pilot?

[Gil]

A nice place for the full size:

Albatros D II / D III news - Page 7 - The Aerodrome Forum

+Gil

[Leif Ohlsson]

Those are indeed wonderful photos, Gil. I think it would be alright to reproduce them here, with a careful note of the source:

The Aerodrome Forum - this post & following

Note that the photos depict two different types of props:

The first is a nine-layered sabre-shaped, like the one I modeled. But the lamination is made with the darker wood at the ends, front & back.

The second is seven-layered straight type, which became more common over time.

I mixed up the order of the photos somewhat. No. 2 is obviously a test-build of the seven-layered straight type, but only one blade. No. 4 is a comparison beween the finished seven-layered straight prop and a started nine-layered sabre-shaped one.

All in all, don't you think the photos (No. 3 in particular!) of the making of the props bear an uncanning likeness to the paper replicas featured here? Makes for a nice feeling when making the models!

Thanks again for this goldmine. The Aerodrome Forum is a most rewarding place to visit!

Leif

[Leif Ohlsson]

Art Deco - first of all apologies if I have mixed you up with Contourcreative on this site. Your handle name made me think that you were working together. Now I see that your are in another part of the world.

Good question about what's next. The thought about a pilot figure was indeed at the top of my mind. Particularly faces & heads need to be worked on when you think about available models. John Griffin's fine pilot figure available as a free download from the Gremir site would greatly benefit from a better head.

Heads, hands, boots, arms, legs, torsos, or a full figure, would be perfect projects for the method. What you need is a good 3D-figure (or head) sliced into ca 0.2 mm thick slices (one layer 160g paper laminated turns out to be 0.22 mm thick on average, I found). This, however, is beyond me, so I can only second your proposition. The idea is free for the taking, and the method works! (I once started working on a 1/87 pilot figure, but never got to the building stage of it. Now I'm sure it would work.)

For my own part, I have been thinking about other sundry details. If & when anything comes out of it, I'll be back. Again, it is a free for all. The three sizes of props should demonstrate that the method is workable and can yield useful results in a wide range of sizes & scales.

Thanks for following the experimenting with such interest!

Leif

[Don Boose]

This is another of your very valuable contributions to the hobby, Leif.

I hope someday to make use of this method. Meanwhile, I have enjoyed reading through the instructions, pouring over the photographs, and admiring your ability to think through these methods, to carry them out, and to describe and illustrate them so beautifully, clearly, and precisely.

I am very glad that you are a member of this forum and that you share your ideas and the results of your research and work with us.

Don

[Art Deco]

Originally Posted by Leif Ohlsson

Art Deco - first of all apologies if I have mixed you up with Contourcreative on this site. Your handle name made me think that you were working together. Now I see that your are in another part of the world.

Please, no apologies! There are many posters here, and besides, to be associated with Contourcreative, even by accident, is a compliment, I'm a big admirer of their models and concept.

Okay, who is going to accept Leif's challenge and design a pilot using this technique?

[Leif Ohlsson]

I realized there was one very common scale missing, namely 1/48. A kit for this scale has now been added to the downloads aviation section on the site.

The kit contains parts for two different props in 1/48 scale, modeling one originally seven-layered, and one originally nine-layered laminated prop. Studying the photos supplied by Gil in previous posts, I realized both variants were made.

After three previous sets of props, I anticipated no problems building the 1/48 version, but you should never become too sure of yourself; there were some new learning experiences, even though I tried to be careful. Here goes:



The nine-layered version (left box) uses scaled-down profiles of the 18-part 1/33 scale prop. For the seven-layered version (right box), I drew new profiles for 14 parts. The nine-layered version thus is slightly thicker. This provides options; judging from photos, thickness of props quite clearly varied.



[Above:] Applying glue through the jellied jig to the prop part below. Be sure to place all jig parts in the same direction top-bottom, and likewise the prop parts in them. You always cut the two halves just a little bit different, and if you turn either the jig or the prop part 180 degrees, errors are introduced. These will follow you through the build.



[Above:] Placing the prop part in the jig. In this kit, small center marks have been added to the jig parts on either side of the hub. This will help to ensure proper alignment without having to stick a pin through the center marks of all parts. I found that greater errors were introduced by trying to hit the center mark exactly with the pin, than letting the jig take care of alignment!



After drying out over night, we are into the fun part of propbuilding. Center holes are preferably drilled now, on the dried-out stack, since you still have a large flat surface to ensure straight drilling.



Cutting off the glued ends of the stack marks the start of the adventure - will the jig parts really separate from the prop?



Peeling is the reward for all your efforts to glue parts straight. The jig parts do come off very easy every time, leaving the prop well glued & unharmed. You can't believe it when you see the compactness of the dried out stack. Petroleum jelly is a great invention.

Fresh out of the mold, the nine-layer prop turned out to be slightly skewed. This is a result of my not glueing the jig parts absolutely straight, or not having cut them absolutely the same. It is much more difficult to glue a stack straight in 1/48 than in 1/16, since the same degree of misplacement, or non-exact cutting, will result in three times larger relative mistake. Also, in a higher stack, errors multiply.



Finished props after a little bit of sanding, one layer of varnish, some more sanding, and a final coat of varnish. Hub parts are printed on grey paper. You must judge for yourself which version is more appropriate for your model, the nine-layered "fat" one, or the seven-layered "thin". (Previous props in this series all are of the "thin" variety.)

Don't be daunted by these notes - they are just some advice to make your build a happy one. These props are actually easy to make; very contemplative when you get into the routine: Jelly, jig, prop, press; jelly, jig, prop, press...

The 1/48 kit is the best of them all so far, with illustrated instructions, and two separate sheets for printing parts on two tones of wood-coloured paper. Even if you don't plan on building a prop in 1/48 scale it might be good to download the kit to have a good one-page set of illustrated instructions handy.

Leif

I attach illustrations of the kit layout. Do not download or save these. The pdf kit for downloading has superior resolution.

[ARMORMAN]

Well done and thank you!

[Leif Ohlsson]

Just to demonstrate how thick, and how curved, a laminated prop really can be, here's an example. It is a Czech Avia BA 122.2, and this aircraft rests at a Czech air museum, not sure which.

I'm counting to 11 layers (with ten fastening bolts instead of the more common eight), and the prop is really thick and really curved, with a very pointed front profile.

The engine, from what I can see, is the ubiquitous Shvetsov M-11 which was used on the Po-2 as well.

Leif