10 Foot Prototype Blade for Molding

[zubbly]

Hello everyone!

Here are a bunch of pictures of a blade i have just completed to hopefully have molded by a company that is willing to produce my blades for me in a carbon fibre/fibre glass composite.

The need has basically arrived by my own needs to be able to sell some generators with the blades also. Even locally where i live, i have been requested to make other people generators, however, what has held me back is the time consuming part of making the blades. Nothing definate, but seems good so far, the final cost in the end product will determine if i go ahead with the produced blades.

I have had much success using Alton Moore's program to make my blades from, and work extremely well with my induction conversions. I also beleive that the blades will be quite adaptable to the dual rotor machines. Very little seems to be available on the market for the more serious homebrew machine in blade availability, and many out there do not want to carve their own blades. I think this blade will be quite adaptable as the hub section will be able to be drilled for various mountings.

The blade i intend to use as a 3 blade prop. The blade is 5 feet long, so will give a 10 foot blade set. TSR is seven, with a tip angle of between 1.5 and 2 degrees, tapering to a root angle of 21.8 degrees at the second last station. The last station was reserved for the mounting hub. The hub section is 3 inches thick by 5 1/2 inches wide,the end is cut at 60 degrees for 3 blade mounting, with the widest part of the blade at 8 1/2 inch tapering to 4 3/4 inch at the tip. The blade thickness at the tip is 3/8 inch thick and the whole curved blade is carved to a usa35b airfoil profile. There has been some special modifications to the design which (with the help of some very knowledgable people on the irc) should prove out to be excellent in performance. As it is now, i know it will work with my conversions very well.

Here are the pics (still not the best camera man around), and i tried most angles to give you the idea of how the blade looks with its profiles.

Almost forgot. I made this blade with laminated pine. The blade has to be painted with a high temp paint for the molding process. I chose to use engine enamel as it is good for 500 degrees.

Hope you enjoyed the post and will let you know how everything goes and if i carry through with having the blades made.

Having fun as usual  

zubbly

[kitno455]

looks well made zub, but i wonder about the noticable change in angle you have at a couple places on your trailing edge, and the skewed tip. seems that those might lead to increased noise over the more oval planforms more often seen.

was wondering what your thinking was with those features?

allan

[Dave B]

Way to go Zubbly ! Keep us posted , I think you will find yourself quite busy if all goes as planned. Great work.   Dave B.

[jorjenzak]

I am real tempted by your generator on Ebay but would like to build my own axial machine as I love to DIY.  But I would be sorely tempted if you had a kit with blades and a gennie too.....

I'll be watching for more info.....keep up the good work!

Jordan

[41south]

And if the guy across the road ever wants to sell his HAM radio tower, I could think of a great use for it  :-)

[wind pirate]

Very Cool Zub

Sign me up when production starts

WindPirate

[monte350c]

That's a good looking blade there Zubbly!

Interesting choice of airfoil. I just plugged it into Profili, looks like a very nice lift/drag curve.

Is the shape for better low wind performance?

Look forward to hearing how the moulding goes and what your prices are going to look like.

Ted.

[veewee77]

Let me (us) know what the cost for these blades will bewhen you get them made.  I am sure there are many (me included) here that may like a set to use on their gennies!

Doug

[rotornuts]

Nicely done. If it goes through info on the moulding process would be much appreciated.

looks like you'll have exellent low wind speed performance.

[ghurd]

Very nice!

[nothing to lose]

Looks good, but kinda odd compared to what I normally see. Maybe it will work better though and that's what counts.

Depending what it costs for them when made I would probably buy a set also. Cost is a major factor though. Lots of times people want something till they see the big price tag.

Heck some of us have trouble getting around to ordering things with not so big of tags too sometimes.

Good luck with them!!

[Victor]

Hi Zubbly,

 The chord looks awfully wide for a TSR of seven. comments?

Victor

[zubbly]

Hi guys, will try to answer most of the questions and concerns here all at once.

Kitno455.   the change in the trailing edge does sort of look "abrupt" in one of pictures. think it is just the way the light shines off the paint. but when you eyeball it from the tip of the blade, it does look rather consistantly trailing. it is a twisted blade. should have included a picture of the leading edge, it is perfectly straight. the tip angle is a little unusual, but speaking with some very experienced prop designers, the skew will serve to make the blade quieter and reduce that turbulance that happens at the tip.

Monte 350c.  not sure what the "Profili" program is, but good to here that the design offers good lift drag curve.

Nothing to loose.  lol, yes the design does look a little odd and different from the normal blade profiles. i am a little odd as well  .  i guess it basically reflects a few different ideas designed into it (good speed coupled with good starting torque). the first set i get up hopefully will bring to light if i am on the right path.

Victor.   yes the chord is wide for a tsr of 7. since most of the work is done on the outer part of the blade, i hope the increase in chord width will add to the overall performance of the blade set. with only a 1.5-2 degree angle on the tip, an increase in chord will add to the starting torque.

Everyone, this blade is a bit of an experiment. the only way we can be sure of getting some good improvements on new ideas is to build and try. i have often seen in some other circumstances (not necessarily gennys and props) that when our design practices seem to tell us that a design is not good, often works quite well simply because we did not make the new design from the old way of designing. very often my "gut" instinct seems to work out i think simply because i have not been trained in the usual set way. this blade will also answer some questions and i hope give the answers for a few people that have spent much time with me looking to improve what we do now.

have fun guys!  

zubbly

[DanB]

That was my thought too... they seem quite wide to me.  

[monte350c]

Hi Zubbly,

Profili is wing management software. Here are the plots for the USA 35B profile, compared with an old standard, the Clark Y. The Reynolds number is 800,000. You can see the lift/drag numbers look good up to around 5 degree angle of attack:

Keep us posted on your new design

Ted.

[rotornuts]

Zubbly, I could be out to lunch here but my feeling is the blade area coupled with the low tip angle should yield decent performance at lower wind speeds if it doesn't stall. I wouldn't bee too concerned with the additional cord width.

[Experimental]

      Really looks good Zub and thinking "outside the box", sometimes produces the best results !!

      The round leading edge, should result in a gentle and smooth stall characteristic , But I too, wonder about the tip width  -- Best test, will be on a gen in high winds !!   Nice work, Bill H......