Modeling-ABC by Wilfried Eck

 
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Making propeller blades / airscrews

Unlike most kit propellers an actual airscrew has a profile gradually thinning to the tip and also changing incidence to zero at the tip.

Due to production limitations and cost most kit airscrews are simplified. especially in 1/72 and smaller. Too rounded and too thick.

If a kit airscrew is too coarse or even wrong there is no need to bash other kits or jump out of the window in desperation. Make it yourself! - It's easy:

Take a sheet of plastic, somewhat broader then the future blade and slightly thicker than required.
   
Heat evenly over a candle or other suitable heat source until the plastic gets sloppy. Remove from flame, pull ends slowly apart while twisting them in opposite directions (This generates the differing incidence angles).
   
Cut in the middle, save one part for the second prop blade.

Scribe outline of prop blade to one plastic part, take care that it's thickness corresponds to the required thickness of the future prop boss.

   
Cut out prop blade.
   
File/sand the front side of the future prop blade to aerofoil profile (rounded on the side adjacent to the prop boss, flat on the tip, front end thicker than rear end).

Take care when making the second one to get the same profile (thicker front end facing to the same side).

That's all! - Exept painting of course.

   
In case the real prop shows clamps and/or tubes, heat plastic rod over candle, wait a few seconds and pull slowly but evenly apart. Cut off part of fitting diameter, paint it and slide it onto prop blade.
   

 

In case an uncovered hub is needed it is formed by parts of plastic rod (smaller diameter into larger diameter), front end closed by a small part of stretched sprue.
 
To get the prop blades fixed in equal angles a template is very helpful, especially with a shortened pin in the middle to temporarily accept the hub.
 
I found it practical to use a pin as prop axle (pointed tip cut off). It glides easily in a tube of a "Q-tip", this assembly being fixed in the motor (maybe requiring to fill the hole for the kit prop accordingly).
 
Add small parts if necessary.
 
Shove complete airscrew onto axle protuding from the motor. If you like to: Blow airscrew to see it spin rapidly.
 
 

Alternative hub:

       
Fill polyester paste into tube of appropriate diameter. Stick a pin (head removed) into center; let harden.

File/sand to required form.

Bore holes and insert prop blades.

 

Example of model with home built airscrews see Firebrand model