we did it !

[jacquesm]

So, actually did it...

After a few weeks of trials, errors and all kinds of stupid mistakes we finally have our first real full size blade.

The day before yesterday (Friday) and today we finished our last 'shrunk' version (25% length) and decided that it was good enough to go and risk another full size trial. Unlike last time (when things went wrong in all kinds of terrible ways) this time it went absolutely smooth. The first pass took several hours (this blade is the right shape, but it could be cut much faster), the frontside another three or so. All in all a whole days worth of listening to the router.

But, it was definitely worth it !

The trailing edge is paper thin but absolutely straight, the leading edge needed a little bit of touching up with sandpaper. Other than that the blade is absolutely perfect (assuming that this is a workable airfoil , but I'm probably not too objective right now...

I'll let the images speak for themselves... happiness:

Small blank for foreshortened blade:

Backside of finished blade:

Front side of finished blade:

Trueing the blank for the larger blade:

Trueing the other side:

First cuts:

Done with the backside:

Halfway down the front side:

Almost done: (look at the neat separation of the remaining blank and the blade)

Its a blade !

Proud young father RonB holding the blade: (notice the centered taper)

In the following pictures you can see how we got all that twist out of such a thin blank, the twist is centered within the blade, so every 'station' has a unique drop on front and back (there are 800 stations in this blade!)

Leading edge of the blade:

Crossection of Profile of the tip:

Trailing edge:

Twist:

Some more twist:

[LEXX]

Very nice!  How much sanding does it need after it's dore on the router?  Also, when are you going to get those on a genny?

LEXX

[brett]

Amazing. Now that is cool. Good work.

Cheers to the pay-off after all that hard work.

Does that blade profile perform best in certain wind speeds?

brett

[jacquesm]

it takes about 5 minutes of sanding, basically only the fibre that got 'wacked' needs a touch up, so do leading and trailing edges. It's pretty clean right off the machine.

The generator is ready to go, the blades are what is holding us up (and the tail!)

[jacquesm]

That is exactly what I would like some feedback on, we've tried to apply all the knowledge that is available to us, but we don't have access to a windtunnel (or good simulation software), and it's a pretty radical design compared to what I have seen so far...

[richhagen]

Hi, that is an awesome looking blade.  I suspect you will get excellent performance from your airfoil.  My only concern in thinking about this is that because the material is thinner at the root, won't it be more prone to breaking near the root in strong winds or gusts?  The torque on the blade pushing it in the direction toward the back of the machine would be the sum (integral) of the force in that direction at each point multiplied by the distance from the root.  I would think of it as a big lever with the wind like your arm on the tip of the blade pushing it toward the back of the machine.  The forces at the root should be large in a gust or strong wind and the strength of the blade at the root should be to some extent a function of the thickness of the material from front to back even considering the material removed for the twist. I may be (and hope I am) wrong on that, but time will tell.  Anyhow, it is far better than anything I have built to date.  Please keep us posted on how it performs, you have had an fascinating project.  Keep having fun, Rich Hagen

[BruceDownunder]

Well, what else can I say ,,  Congratulations ,well done, very professional .

I'm now waiting for the upgrade on the router --can I see possibly "ganged" multi-routers ,to speed things up ??.

Bruce

[zubbly]

Super job guys!

wish i knew a little more about blade design. looks fantastic to me  

My hat is off to both of you!

zubbly