Building a Prop

[Bill Wightman]

Dan,

Real nice work! Cool duplicator machine.

I'd like to know what airfoil(s) you chose.

[DanH]

Bill,
From the software documentation:

Prop Optimizer PRO uses the classical Goldstein-Theodorsen vortex theory to calculate propeller aerodynamics.

The program uses the NACA 16xxx series airfoil. It is based on a uniform loading mean camber line. This provides the maximum lift with the least camber which helps raise the Mach number for drag divergence and reduce shock noise. The thickness profile provided has a 60% aft minimum press location to help reduce profile drag. This is ideal for a propeller airfoil but not suitable for wings due to the high pitching moment caused by the more aft loading.

I'm not savvy enough in aerodynamics to offer worthwhile personal comment.

[szicree]

Dan,

How in the world do you clamp such an enormous glue-up??

[David_Nelson]

Dan,

What you've created is simply amazing! Unfortunately, there isn't a 'jaw dropping' icon here. I guess this is the closest one:

Thank you for showing your talents and sharing your knowledge and expertise with the group.

/\/elson

[Geico266]

One question Dan, do you make bird houses too?

That is amazing. Is that duplicator machine thingy homemade?

[DanH]

Steve,
<<How in the world do you clamp such an enormous glue-up??>>

For the master half-blade, I picked up some nice boards outside Atlanta at a specialty millworks supply and Raymond clamped them with a simple fixture. No big deal, just a flat 2 x 10, a bunch of crossbars, and a lot of threaded rod.

I priced maple too, and was planning on the same thing (just longer) for the prop blanks. Then I got thinking about a prop I'd seen at S&F made from 1/16" maple veneer. Very pretty! So I made a few calls and found out most of the prop vendors just order laminated veneer blanks pre-glued.

I ordered two from a company in Michigan recommended by a prop guy I trust, at $450 each. The millworks said no problem, made them, and shipped them to me. When I cut into them I found some open glue joints. Uh oh!

It was simple enough to track down. The veneers are fed through a glue spreading machine. As they come out, the workers stack them on the clamp table. The catch was the thickness of these blanks, and the fact that they made them in July. I needed 104 laminations, and the glue machine only runs at one speed. It wasn't running fast enough to kick out 104 layers before the glue started setting in the July heat. They had never tried to lay up a veneer prop blank this thick in the summertime; not many crazies building props with 6.375" hubs.

The millworks owner was square about it, and I agreed to drop the veneer order and let them plane 1/4" laminations instead. "Only" needed 26 of those, so no more problem with glue machine speed. They replaced the bad blanks, no charge.

As I didn't wind up with the sexy veneer blanks, they probably cost us a bit more than just laminating boards myself. What the heck, it's only money <g>

[rgbewley]

Hey there #1. You are the quintessential man. Really proud of you. Say hi to Miss Patti for me.

Rhonda

[DanH]

Larry,
<<Is that duplicator machine thingy homemade?>>

Yes...a little welding and machining. Anybody want to buy it? I'm probably going to put it on Ebay.

[panhandler1956]

I'm speechless. I love this kind of thing!

I really appreciate that some of this 'lost art' stuff isn't lost in the modern CNC kit-builder world. This kind of 'problem solving' is inspirational.
I'll remember this post when I am frustrated about how to solve a particular challenge on my -8 construction.

Patience (no shortcuts and pay attention to the details), patience, and more patience.

Kudos to you Dan for keepin' it real!

[Lars]

When people learn that I'm building an airplane, I tend to correct them and point out that I feel like I'm an airplane builder in the same way that someone who buys their furniture at IKEA is a furniture builder.

The breadth and depth of your knowledge and talents is amazing. Thanks for sharing!