Laminated prop in paper

[abufletcher]

It's a real 1/6 scale version of the German Integral propeller used on some (but not most) Albatros CIs with the Benz BzIII engine. I matched the layering on this one directly from a photo in the CI datafile. So at least for this specific prop, this is the correct number of layers and the correct shape and pitch.

[BrianTJohnston]

Regarding your comments about aligning the layers to avoid distortion, this was something that worried me when I was thinking of trying the method. I was originally just going to fix down two straight edges at right angles and put the laminae in that, but when I got out to the workshop the idea grew.

This was the result; basically I started out fixing three pieces of alloy angle to a piece of blockboard to produce a rectangular opening of 100x15mm for a 1:33 prop. However I wasn't happy with the surface of the blockboard for clamping against, so I fixed a piece of brass shim with its edge under the front edge of the long angle and matched that with a narrow strip under its back edge to maintain the vertical face. I then cut a length of lighter angle to use as a pressure plate on the top and found a pair of small clamps as a pressure source. Finally, I made a pair of feet to provide space underneath for the clamp heads. The advantage of this is that it is not necessary to glue the jig sections together; the angles hold everything in alignment. My first attempt can be seen in the picture. All worked well apart from a problem of avoiding Vaseline on the prop parts and getting sufficient glue on them; I have a lot of not very well glued laminea in this first one!

[BrianTJohnston]

What I forgot to say is that while you can't build the whole prop in one go (unless you are lightning fast) you can easily do six layers at a time, thus reducing the time spent watching glue dry!

[Leif Ohlsson]

What a fine toolmaker you are, Brian! It is such a joy, isn't it, tinkering with thingamujigs like these.

Also, it is always nice to watch another laminated prop seeing the light of day. And I agree, you can make a certain number of layers at one go. My measure was when the paper pile started to buckle. Then you would really have to let it dry out under pressure for a while.

Leif

[BrianTJohnston]

I don't think I've ever been accused of being a fine toolmaker before!! Generally I just muddle along. I'm going to try 1:16 version, not that I'm currently building anything to that scale, but just for the fun of it!

The beauty of building jigs as I do is that a visit to your local metal merchant will generally secure a selection of offcuts from their scrap bin for peanuts.

Brian

[southwestforests]

That is some serious modeling.

[Leif Ohlsson]

This photo was taken recently at the Sopwith Miniature Aircraft Works, at a visit by Mr. Claus of nearby Laminated Propellers (LamProps) Ltd. The occasion was introducing the new simplified laminated prop replica, which had just been developed in a prototype version at LamProps.

Mr. Claus – or "Santa" as he is affectionately known in large-scale aircraft modeling circles – had got wind of the production bottleneck at the Sopwith Works caused by the desire to have really fine propellers mounted on their new models, the Pup in the photo among them.

While working on their old model of 36-layered laminated paper props, the skilled workmen on the LamProp factory floor had stumbled on an – in hindsight – obvious feature of all propellers, namely that they are in principle built up of only two surfaces, twisted around each other. While laboriously sanding away on the rough-cut propellers, workmen starting sanding on the front side of one blade found themselves ending up at the rear of the other blade – all the while not lifting their sanding blocks from the prop at all.

From this insight it was but a short step to jot down a sketch for a complete redesign of the propeller-making process and leave it in the company suggestion box. Why not, these workmen wrote, design two pieces, attach them to each otther, twist them roughly 180 degrees, and insert a suitable hub in the middle?

Mr Claus – who is a most progressive thinker although his general manners and apparel may not readily disclose it – soon saw the possiblities and set his chief designer on the task of drawing up such a propeller, which promised to greatly simplify production. In order not to upset more conservative customers, the design specifications included a clause that the pattern of an original laminated propeller was to be painted on the surface of the new version, thus making it virtually indistinguishable from a truly laminated propeller.

If photos can be relied upon, the new propeller looks every bit as good as the old version mounted on the Pup in the photo, and in some respects even better. It remains to be seen, however, whether discriminating customers also will appreciate it. In order to find out whether this is in fact so, "Santa" is offering any miniature aircraft constructor his new propeller in a so-called beta version. It comes in two scales, 1/16 original, and a 1/33 scale version to appeal to the latter large group of manufacturers.

It is to be expected that the final production version will include proper wood textures. This is what the present beta version on offer looks like:



Prospective test-builders of the new prop are requested to direct their orders to Mr. Claus' agent for propeller matters, Leif Ohlsson of Papermodelers.com. Orders may be placed by PM, and shall include a regular email address to enable shipping. The beta version will be delivered as a 2.1 MB pdf-file formatted to suit both A4 and US Letter printing formats in any inkjet printer.

In a personal communication to the present correspondent, Mr. Claus of LamProps ensures all concerned parties that no reindeers will be exposed to danger of any kind in the delivery process.

[Tapcho]

[double post, my bad]

[Tapcho]

This is absolutely ingenious! Thanks Leif, just because of this I now have to consider of building an aircratf. :-)

Tappi

[ARMORMAN]

Leif....I think has been sniffing glue again.....