Plans Page 2
Click or press the pic for Penny Plane plan
A good Penny Plane prop from Tom. Enlarge to 6" x 2". Make the spar 4" long (tapered 3/32" or 1/8" and slightly flexible to allow the prop to flare under high turns. Set to 23" pitch.
To encourage you...
Here is Derek Richards' natonals winning Penny Plane. You can make the construction easier by hanging the tail on 1" long posts UNDER the boom. Use tissue tubes which are JUST a slide fit on the posts. Careful choice of stiff, LIGHT wood (but not 'cheesy' wood) is essential to get down to just over 3 gm. Use rubber from .087" to .125", depending on weight. The aim is NOT to overpower the model, because it will shoot up to the ceiling (and comes down almost as fast because the turns run out while it is high up). You want to aim for a rubber thickness which leaves you just a few turns when the model touches down. Take particular care to build in the warps as shown on the plan. Build in 2 deg of left thrust on the prop bearing. This will give you a nice climbing left-hand turn which will handle high motor turns well. See the article on easy film covering....
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Very good 12" dia x 23" Pitch Prop used by Tom Tomlinson - has won many competitions including several Gold Awards at The BMFA NW Indoor Gala and a Bronze Award at The BMFA Indoor National Championships.
Make the spar from medium 1/16" square balsa rounded and tapered to the tip.
The wood should be strong enough to stand the occasional bump, but flexible enough to allow the prop to flare slightly under high turns. If the model is down to 3.1g weight (without rubber), Try rubber about .080" to .085" wide, about 650 to 700 turns after breaking in for a .75g motor with .75g ballast (NORWIND rules).