PVC Airfoil Experiment

[MacGyverCanada]

I've built a few blades by cutting cardboard shipping tubes, so I know that a simply cut PVC blade will work.  Basic cuts below:

So I think I'm going to skip that step in turbine construction.  However, I just acquired a few lengths of scrapped PVC for my next project, so I'd like to try something.  I'd like to bolt a somewhat stiff material to the pvc, such as a thin laminate wood or a stiff plastic sheet.  Then I would like to cover the resulting structure in a film of some sort.  Fibreglass would be nice, but I'll probably try something different.  Perhaps the stuff used to wrap those big white "marshmallows" made from hay..?  Then I'll put some reinforcement on the leading edge to make it a bit more durable.  The result should look something like an airfoil, at least in theory.  I know Occam's Razor should apply to any practical projects, but I'd like to have some fun and learn a little on a minimal budget.  The sketch is below:

Black: PVC pipe

Brown: Wood..?

Light Grey: Film

Dk Grey: Bolts

Blue: Flashing

Thoughts?

[TheCasualTraveler]

     I don't understand what your going for but I believe with all the various bits it's going to be a bugger to balance. PVC is so simple and rather than reinforce thin walled pipe, I think the thickness should be increased. I built a set using 6" diameter pipe with walls about 1/4" thick and they were plenty sturdy for a 60" diameter prop. I used a belt sander to get the tips shaped into a very nice airfoil, flat one side, curved the other and mounted with about a 5 degree angle at the tip and they spin quite effortlessly.

     If it's for your own learning then fine but I think there are much better and less  time consuming ways to make a nice blade set. Sorry to sound discouraging but blades can be so easy for a small hobby mill.

[MacGyverCanada]

I getcha, but it's for the experiment more than anything.  

Mostly I'd like to know if anyone thinks that this WILL NOT work, either because of the design or because of the materials involved.

[hiker]

SAW this on pbs-this old house-any way if your lacking a saw you can cut

that white pvc with a bit of strong string-just lay it on top and move it back

and forth with a bit of pressure--must be the friction -the string heats up and

cuts right throu..may work on the black pipe as well...... :}

[MacGyverCanada]

Hmm thats neat, I wonder if braided wire would work better?

How much camber should I try and have on the root/tip of this beast?

[ghurd]

Might try a square pail.  Sam's Club puts laundry detergent in them now.

One corner and side would give about the same air foil.

Wouldn't be very big blades.  Would be a lot easier!

G-

[Rover]

Actually I'm more intrigued that you made blades from a cardboard shipping tube. Was iT water proof?

I've been playing around with small cuts from an 8" cardboad concrete tube, seeing if I can saturate them with epoxy. ( I had the tube I had the epoxy I was bored) . If I can (not easy .. using an acetone/epoxy mix now) might be blade making stuff. But If I can get it from absorbing water (I'm doing immersion tests on the attempts) , I might make blades from it... depending on how much epoxy it will take.

[Ungrounded Lightning Rod]

I'd think that painting them REALLY WELL with a good waterproof paint would do the trick.

[MacGyverCanada]

I've decided to forgo the 'skin' of the design...  I don't think that my airfoil will be affected too much with the scale that I'm working on.  I built a one-blade prototype from cardboard to test the blade design; it spun very nicely in just the lightest puff of wind!  I cut the PVC spar sections this morning.  Pics of the prototype and spar cutting will be up soon.  

My next two things to do are to find a suitable material for the actual blade (thinking either fish boxes or vinyl siding) and I still have a pair of Ghurd's controllers to assemble...

[Rover]

I just finished a set of 26" blades using a concrete cardboard tube. Ok I cheated, I laminated 3 layers of fiberglass on each side of each blade sandwitching the carboard.. they have been flying for about 3 weeks, and in heavy rain.. no issues yet.

[MacGyverCanada]

It's coming along slowly...  It should be flying before May!