mini blades from 1.5" 3M blue foam

[pickerol]

Had a lot of fun making some small blades out of 1.5" 3m blue foam; 9"/28 degree root, 1.5"/0 degree tip. Fiberglass and epoxy have made these blades very strong and light. The entire unit including hub is 3lbs...52" from tip to tip. I can actually lift the enitire unit by the tips, hanging the 45lb PMG from the center...any give is barely perceptible. I'm hoping to get 150 watts in a 20 mph wind.






I'm hoping to use this wee mill to top up my future electric bike. They're going to be legal here this spring. The mill should be small enough that I can use it without alerting the building inpector...lol.

[Bruce S]

Pickerol;

Nice set of blades. What kind of wood are those attached to or is that pixel distortion?

E-bike? have you already started? what kind of motor/control do you plan on?

We here at work have a somewhat commercial unit built in the Netherlands.

We've learned alot about batteries, charging and what the real world takes to make an enclosed unit usable year round.

Great of luck

Bruce S

[Bruce S]

oops,

Sorry that meant to say Greatest of Luck!!

Bruce S

[kenl]

 Like the blades!!! How about some info on how you carve them.

[pickerol]

Hi there,
The dowels and hub-plate are both knot-free Oak. The begining of the root is 1.25" marine ply cut to the airfoil shape and drilled through so the dowel extends 4" into each blade...two chopstix extend as well! The dowels are positively connected to the blade skinsuntil they end and adhered to the foam with lots-o-epoxy.



In this case I only used one wood section on the end.
I'm not sure what kind of batteries to use for future e-bike but any suggestions would be appreciated. So far I have a rear hub that free-wheels on both sides in the same direction; regular gear cassette on the right side and a free-wheeling 16 cog on the left. For the motor I have an assortment of pmdc types that may work with 36v...one treadmill motor shows promise. Speed control is from a large senior scooter...other options include a treadmill speed controler and one from a lathe. It's amazing what you can find in certain sections of the dump! At any rate I won't be mounting the thing on my carbon road bike or cyclocross winter bike! Still need to find a decent beater-bike to add my parts. I think I can have a quick release for the motor as well, since it will basicaly sit on the rear rack with the chain decending straight down to the 16 cog. With this arrangement the motor chain only spins when power is applied, rider can choose to add to the motor power by peddaling or coast and let the electric motor do all the work or coast with no drag from iether drive except for the free-wheeling mechanisms. still lot's to consider but hoping to have the entire system (mill + bike) demonstrable this summer.
Appreciate the encouragement
Tom

[pickerol]

Very simple. I shape with a file (rounded/flat) -the kind fiberglass layers use. This sucker takes down large-rolly-bits! I finished with a flat sanding board...the red kind (aluminum oxide?) of sandpaper...yields a very smooth finish yet can still removedlots of material easily. To give you an idea how easy this stuff is to sand...my nose-cone started square and I hand carved/sanded it in about 10 minutes (one smoke and a few mins more))
Just need wind!!!!

[coldspot]

Great blade

Also great

E-bike info, (It's on my dream list)

I"m planning on trying a treadmill motor with

it's own speed controller, (2.5HP, 120 VDC 7100RPM).

A little "Foam Wing" trick I know-

Find some "Plastic BANDING"

It's like the metal banding you see around better built

crates or cardboard box's.

Use this plastic as a spar, (Stuff will coil up but will not bend edge wise)

You only need to slit the foam with razor blade and slip it in running

full length.

When I get that far along,

Making some Foam blades

I"ll also cut a section down, (about a fourth, widthwise)

And slip it into the "Leading Edge".

I once cut a plane in half, when a mid-air collision with

that plane and my wing happened! (RC Combat Days)

My plane was only a Ditch to fly and when I got it down,

My wing was shifted off square but the leading

edge was allmost unmarked, (very lucky to go thru other

plane at a point were it missed rear control linkage and

RC componets).

Anyway

Just my

$0.02

[willib]

nice work !

[pickerol]

Plastic banding...holy smokes...exactly what I used to connect spar to the skin as well as epoxy filled holes. Super strong combination but when/if it explodes it should produce quite a bang! My blades are so wide because I figured a lot of torque would be required in this application (TSR of 9?) still need to see these suckers fly...hope they're not to bulky to get up to the higher rpms...who has seen the wind?

[kenl]

 Thanks for the info. Went to HD yesterday and found the foam pretty affodable. How about the glassing? Do you cover the styro before you do this to avoid meltdown?

[pickerol]

DO NOT USE GLASS! You'll melt the foam no matter how you try to protect it. Epoxy works perfectly. I use the 4 hour kind. Coat the foam well and wait about 30 minutes, apply the fiber material and smooth really well. I resmooth a few more times in the next hour. Next layer of epoxy (next day) is painted on after a light sanding. I used quick setting epoxy to touch up certain areas and build up the edges. I recently painted everything with plastic paint.

[kenl]

 Thanks for the info on your blades. Think I'll try  my hand at it for some PM motors I've picked up over the last few months. Still collecting parts for the axial machine.