New Sport Turbine

[Walter]

My new Sport Turbine is up and flying. I used 7' Chinese blades but they needed a lot of reshaping. The 35' tipup tower is made of 10' lengths of 1.5" steel pipe welded together. I got them at the  Depot and wish I had used 2" pipe for just a little more money because the tower does a snake dance in winds >20 kts.



I bought a Hamilton Ferris generator long ago to produce power on a sailboat by towing a propeller astern coupled to the gen with a twist line but that project never reached fruition.  The generator measures 4" diameter by 7" long. It is brushed and I think it is probably shunt wound.

But, the output is very low. At 20 kts of air, output into a 1 ohm load is only 5VDC. Open circuit voltage is 10 VDC. I queried H-F and the salesman thought I was not spinning fast enough. He said it needs 400 rpm to charge a 12V battery. I am not set up to measure rotation rate but the blades look like a solid transparent disc when up to speed

I am wondering if a jolt from a 12 V battery would help to get the magnetism going. Its either that or lower the tower, disassemble the head and test the gen on the bench.

Advice is appreciated.

Walter

[DanB]

Yes - if the cutin speed of the alternator is 400 rpm, that's way too fast for 7' blades.  You're blades are likely overspeeding most of the time, which may also prevent proper furling (looks like you have it setup to furl)

I am also worried about the use of 1.5" pipe for the tower with a 7' machine (especially if it's over speeding)

But - overall it looks like a nice effort and thank you for sharing pictures!  I would consider doing a few things differently though based on what  you've shared so far.

[hiker]

gear it up--may burn it out thou with those blades..?

[Walter]

I was not clear. The blade circle is 7' diameter.

[DanB]

right - yes, I gathered that from what you said.  400 rpm cutin is about twice as fast as it should be for blades that large.

[Flux]

Don't follow this  I assumed you had a Chinese turbine but I get the impression from others comments that you have used the Chinese blades on your generator from the hydro turbine.

We are guessing about your generator, the blades and virtually everything else. If your generator does actually cut in at 400 rpm then your blades are quite slow. The Lucas Freelite cut in at just over 400 rpm and had 6ft blades. It produced power in winds above 10 mph and would have been doing quite well at 20kts.

You also worry me when you say that you had 10v oc and it dropped to 5v with 1 ohm. I doubt that this small load would have slowed a 7ft prop significantly in a 20kt wind so I strongly suspect that the little generator was not intended to produce much more than a trickle charge.

You need to do some bench tests on the generator and I think you are likely to find that it is not much use for your job.

Your blades are likely intended for a Chinese PMA with significant drag at start up and are probably are tsr6 or lower. You need an alternator that cuts in at no more than 200rpm to match them properly.

Flux

[Walter]

I don't notice any appreciably blade slow down when I switch the load so I think most of the voltage drop is armature resistance.

[ZooT]

I like the telecaster tail :-D

[Walter]

Tomorrow I'll rework  the head with a v belt drive to give, what, a 2:1 step up from the prop to the generator?