My First Turbines Nearly There

[Muiller]

Hi

Just some pictures of my first 2 turbines i am building.Thay are 12' Hugh Piggott designed turbines 12volt 1000watt.

10mm thick steel disc with 16 x 40H 46x30x10mm mags.





The rotor with the resin on it.





The stator wire windings all ready to be cast,25 turns of 1.80mm,12 coils in total.





The first set of blades and tail.





The second set with tail and center,1 blade missing as paint was not dry





The profile of the blade.





The tail arms made from 2 inch angle.





The bearing/Hub from a BMW.





And finally the winder and wire,50lb of wire in total split over 2 rolls.Good fun so far and hopefully it will be the same with the rest of it.

Thanks for looking :-)

[jmk]

 Hello Muller, It looks like you have been having great fun. I like your progress. You are doing good work. I built the 12' machine too. I noticed something wrong with the blade profile. The thickest part of the airfoil should be 1/3 of the way back from the leading edge. It looks like you have it right at the leading edge.  If you use the same planes I did watch out for the error in the way the tail gets mounted or the tail will fly on an angle. I had to modify mine after I had it up once and all welded. I cut it apart and added a piece of steel to the bottom  2" angle to kick it out straight. It will work fine crooked but it looks funny. Also I have found that if your tower isn't rock solid plumb the tail has a hard time furling because it's so heavy, and if the angle in which it's mounted grows steeper when the tower top moves it makes it harder to furl . If you didn't weld the hinge to the end of the tail yet you may want to make it so you can adjust the angle that the tail will have to climb so it can go to a less steeper of an angle. It may be easiest to do it at the tail lug welded to the machine with two different holes to use. I think it's better than making the tail lighter. Hugh's 12' machine is a heavy duty machine made to last a long time. I think making the tail lighter can shorten the life span. His angles are pretty much right on when the air gap is tight without to much line loss. If you have a larger gap and a long line run the blades speed way up to scary speeds when the tail tries to furl otherwise. I want to change the angle on mine I just thought I would give you a heads up. Every machine in it's own environment runs differently too. A different hole to pin the tail at the bottom of the tail would be a nice feature. You may decide to just make it furl early that way. Just my two cents, John.          

[Flux]

Yes something seems to be seriously wrong with the blade profile. Looks as though you have forgotten to reduce it to thickness before working the profile on the back.

You also seem to have a lot of wasted space in the winding but I am not that familiar with the 12ft machine. I would have thought you only have half the copper that I would have expected.

Flux

[Muiller]

Hi there

Thanks for the comments.

The coils are the right size 25 turns of 1.8mm 2 in hand,I think it the way the picture is taken(photography is'nt my strong point.they are pretty tight when cast.

The blades are another matter,I am VERY WORRIED about them,I built then from the dimensions given on Hughs book they are 22mm(Just under 1 inch) thick at the tip and are 50mm(2 inches)at the root.

I took some more pictures that might help.

The wood beside the blade is 50mm(2 inches thick),And is the thickness at the root.

Agian the wood the blade is sitting on is 50mm(2 inches) thick.

DOES THIS LOOK RIGHT NOW??

Or did i Make a mess of things? :-(

Or should i keep away from cameras :-).

Thanks again

Im Very Very Greatful for all the comments GOOD or BAD

[Muiller]

Sorry for posting again.

Forgot to include it in the last post.

This is a Question for John(jmk)

You said that you would take the bottom of the hing in a bit by drilling an extra hole(or 2) to reduce the angle,That sounds like a very good idea an i am going to try it.

What kind of a drop do you think would be good?

I was thinkig as the allthread is 19mm i would drill a hole 25mm for the center on the inside of the original hole which should drop the tail a bit,This would leave 5mm of steel between the 2 holes,Would that be strong enought or should i leave a larger gap

Thanks Again

[Flux]

Looks far too thick at the tips.

Check the instructions again. I don't have any details for the 12ft prop but Hugh normally gives a thickness for the wood behind the leading edge as a parallelogram then you work the shape into that thickness. I would expect no thicker than 3/8 at the tip and probably less than that.

Your flat driving face looks ok, something has gone wrong with the thickness. I wonder if you have measured it from the wrong surface.

Flux

[Flux]

I have found some early information and the thickness was 1/2" at the tip.

5. /8" at 60"
   
3. /4" at 48"
   
7. /8 at 36"
   
1. 1/4" at 24"
   
   

This should be near enough for you to see where you have gone wrong.

Flux

[Muiller]

Thanks Flux

I SEE WHAT I DID WRONG

The brown coloured blades are built correctly,

But the blue ones are not as i was in a rush when i was doing them,And forgot to check the thickness,

This is the way it should be

Root      =  50mm

station 1 =  30mm

" " "   2 =  22mm

" " "   3 =  19mm

" " "   4 =  16mm

Tip     5 =  12mm

Thanks for that

[Flux]

Sorry about the decimal points, that should be 5/8" etc.

Flux

[jmk]

 I don't know the metric system very well so I have to reply in standard. I would go with a smaller bolt about 3/8" in dia, but use a hardened one. You probably wont need much in the angle change to make the tail furl sooner. I would think a hole that leaves 3/8" of steel in between the two would make it so the tail can furl a bit sooner. You will have to make sure your tail hinge parts have enough clearance to swing with the extra. Plus you will need a little bit of play to change the angle. The tail will want to get tighter as it swings with the bolts not lineing up as a straight axis on the lower one.

 I think Flux is right about your coils. I thought the same thing when I viewed it the first time but forgot to mention it. 25 turns is two in hand did you hold two in hand when you wound the coils? The coils will just about be touching together with the right amount of copper. You have lots of room for more copper. I hope you didn't cast them yet.      

[jmk]

 Ok, I see you have two in hand by the picture. It still looks light on copper but maybe it's the way they are laying there? Did it take around seven pounds of copper to make your stator? I bought an eight pound roll and had about a pound left. You can check your resistance two. He gives you wieght per coil and resistance in the plans.

[jmk]

 Looking back at my stator it has more room than I remember. I think it's just the way they are laying in the picture.