Pennyplane Discussion

[builderguy135]

I'm planning to make an LPP this summer (Bill Gowen's Carbon Penny)

In his plan it says to apply 2 layers of CF rods to make the wing tip plates. How would I glue that?
Screenshot:
https://photos.app.goo.gl/iTZoMX22P93MYz489

Also, I don't have any jig to mold my propellers into the right shape. How would I make one (3d printed?)

[bjt4888]

Builder,

Bill Gowen did a sequential step diagram for the wing tip. I’m thinking that it is in Hip Pocket. Sorry, I am not home right now and don’t have the best internet connection (on safari in Africa).

You can make your own propeller mold in a couple hours using the Hobby Shopper method. I “plank” the beveled surface instead of carving/sanding foam as shown though. Also can buy molds from Mike Kirda at propblocks.com

Brian T

[jander14indoor]

INAV Hobby Shopper already mentioned, its in the link I posted already.
You could 3D print a form, but it would limit you to air drying, no tossing it into the oven to accelerate drying. Might want to add drying holes to the surface you form on to increase drying rate.
Air drying isn't much of a constraint if you plan ahead, normally only takes a couple of days at most. Oven drying can speed up to less than an hour, though you risk burning the wood if you don't have a real low minimum temp in your oven.

Jeff Anderson
Livonia, MI

[coachchuckaahs]

We built this model, and the build was simple.

Note that the page you posted above actually has the step-by-step to make this part (tip plates). No shape form is needed, it self fixtures. Build it with one rod, then lay the next rod against it an a dot of thin CA will flow along and join them together. Could use thin duco as well.

On prob block, you can build one with balsa. Or 3-d print from the one Don S posted to Thingyverse. We used that one for our LPP's. We put the blades on it after brief wetting in sink, then heated in microwave at 40% for 3-4 minutes. No melting problems, and they came out nicely dry. We used a 1/16" overlay to protect the blades, and wrapped with "Pet Wrap".

Coach Chuck

[coachchuckaahs]

Actually, looking at the page you posted, I think the curved parts were a single 0.010" rod. Perhaps the vertical was a double? If so, just lay them together, a drop of thin CA will spread along the whole contact area. Or take a 0.020 rod and split it in half with a razor.

Coach Chuck

[builderguy135]

Thank you so much for all of the help! I'll try to update once I'm finished with my propeller. My prop hub is already done but I still have to find the right size shaft and sand/mold the prop blades.

Where can I find the 0.016"-0.018" music wire? I found a few used violin A strings (approx. 0.019") but it's too thick for the pennyplane bearing on Ray Harlan's website. I was thinking about just using the regular SO bearing on his website but it's significantly heavier. Not sure what to do since the right size music wire comes in much larger batches, and it's much more than I need. Any advice?

[bjt4888]

GHS “plain steel” guitar string is excellent shaft wire. If not available in your local store, order from Elderly Instruments online. Cut it to length, debut the ends and then, spin slowly in your fingers to detect slight curvature and remove curvature by bending by stroking the length gently. Several passes of straightening usually is necessary. Only takes a few minutes to straighten.

[jander14indoor]

there is another trick to straighten wire.
BEFORE you cut it. Suspend it vertically with a weight on the end heavy enough to just pull it straight (elastically). Twist until yield. Remove weight and check to see if it hangs straight.
Start with one or two turns, check. If not straight, try three, check. And so on.
Not as effective on already hardened wire, but I think it should work on music wire.
AND, WEAR SAFETY GLASSES IN CASE THE WIRE SNAPS!

Jeff Anderson
Livonia, MI

[builderguy135]

Finished my LPP.

Stab: https://photos.app.goo.gl/u9bRZJGbXr9aZJos8
Propeller: https://photos.app.goo.gl/DVgd3f5Y42apWfWb8

I used 3/32 Tan SS Rubber, 2.62g.

Launched with 1500 winds, dewinded 300.

My flight today (outside!) brought the plane to 15' within less than a minute and it cruised there for about 4 minutes, didn't go any higher. Flight ended after it hit a tree at about 5-6' off the ground. Luckily nothing broke but the final time came to 4 minutes and 31 seconds.

https://photos.app.goo.gl/Lb3RBvzWSDqyVydD7
Video: https://photos.app.goo.gl/4WuBNJt7BR1VXjd5A

Sorry for the terrible video quality.

(Copied from my HPA post, will edit with more info)

[jander14indoor]

Congrats! Though I have to say you are a brave one to fly a Penny Plane outside!

Jeff Anderson
Livonia, MI