Plastic blades on a F&P Genny

[nweeks]

This is the plan so far:

Blade Material

Using a 44 gallon plastic chemical drum for blade material for the following reasons:

Thicker at the bottom

chemically inert

UV stabilised

Cutting the Blades

Profile has one near-straight edge for leading edge.

Cut out blade profiles with the blade root

at the bottom of the drum(thicker plastic).

Before cutting, slip the blade template a few degrees off perpendicular

to get a twist in the blade

(tip is slightly further around the drum than the base)

The Hub

Use a hub from an old all-steel radiator fan

(very similar to Gizmo's (http://www.thebackshed.com) hubs

Remove the steel fan blades, and bend the blade mounts to the curve

of the plastic blades

Bracing plates made from 2mm Aluminium similar to Jerry's (http://www.dplusv.com/Photo-03.html)

The F&P

A Slight rewire - divide the windings in half - two star

windings.

Two three-core leads down the pole

Allows you to parallel or serial connect to suit loads

transformer and rectifiers to pull down to 12/24/48v

Decogging

555 timer, Decade counter with reset pin on third output, MJE3055 transistors to shove a cascading 12v back up the line to the genny - simple kick-start to get it rotating.

(Could even be used as a frost-preventative measure (Produces wind) in vineyards, etc...)

Might just round off edges of laminations on stator - a little simpler that electronic kickstart

[domwild]

Great stuff! As I do not have a black belt in electrickery, would it be possible for you to give us the schematic of your kickstart method to get around the cog?

Have wondered if a straight trailing edge is OK as most commercial blades have about 1/3 of the chord on the leading edge and 2/3 on the trailing.

I have a suspicion that a sharp edge on the trailing edge and rounded leading edge will make it more aerodynamic; a pipe profile like that is similar to the doubly- chamfered profiles of early aeroplanes.

What do you think of the Jerry method of using caps and treating each phase separately with rectifiers (if DC is wanted)? Would you use two of three-core cables, i.e. two doubly-insulated cables or six singles? Which is better for allowing a twist?

Too many questions!

Dominic

 

[nweeks]

The circuit is fairly simple.

A square wave generator (555 timer) feeds the clock pin of a 4017 decade counter.

With each pulse, the decade counter moves an output.

Connect the third output to the reset pin, so that the outputs go:

1 2 3(reset) 1 2 3(reset) and so on.

In my files collection is a project that contains all you need to know.

http://www.fieldlines.com/user/nweeks/files

It's an electronic dice project - move the reset line to the third output, and substitute the output transistors for big mothers - 3055's are 10-15 amp on a heatsink - available in flat packs(MJE3055), and TO-3 packs (2n3055)

Better put free-wheeling diodes on the outputs - FP motors make big sparks when you put voltage into them - you don't want the Transistors letting out their smoke..;-)

Two three-core flex cables are planned - cheap as chips, and I need ~240V for driving a pump, as well as 12VDC for the hut.

I like this site! Only been here two days!

Nige.

[commanda]

Decogging

555 timer, Decade counter with reset pin on third output, MJE3055 transistors to shove a cascading 12v back up the line to the genny - simple kick-start to get it rotating.

You'll need a series diode with each transistor, and a parallel flyback diode to protect them once the genny starts making volts. Also, if the F & P is making 240 volts rms, that's 340 volts peak. Exceeds the Vce breakdown voltage of the transistors.......precious smoke will escape.

Also, once you've finished with the kick-start, and the genny is making watts, you want all 3 transistors turned off.

You also don't need the "slow-down" part of the dice circuit you have posted.

I would use the kickstart push-button switch to supply power to the circuit (in series with the +12 volt supply); then all 3 transistors will be off once you release the button.

Amanda

[nweeks]

Woops, wrong terminology: Free-wheeling instead of flyback diode.

Yes, the circuit is only good for the 555, 4017, and some of the output stages - only take the bits you need...

What is the breakdown of an MJE3055/2n3055? It's about 150V isn't it?

That's a bit of rotation before you let the finger up...

I had a bit of a think about this last night - using the hall effect sensors in the FP, and a simple to wind sensor to do all the triggering automatically, with attempts about 30 seconds apart.

Dunno, probably not worth the thinking time - pressing a button is far easier

Nige.

[BT Humble]

Great stuff! As I do not have a black belt in electrickery, would it be possible for you to give us the schematic of your kickstart method to get around the cog?

The curent issue of Renew magazine (http://www.ata.org.au/about_renew.htm) has some details about electronic and manual de-cogging techniques.

The simplest method they mentioned for de-cogging is to use a file to round off the metal ends of the stator poles just a little bit (ie. 1mm or so).  Apparently this reduces the cogging by up to 40%?

I'll scan the diagram and post a picture if you like.

BTH

[commanda]

That's a bit of rotation before you let the finger up...

Yes, but once you let your finger up, aren't the transistors still connected to the windings?

Some specs. 2N3055 TO-3 case Vcb = 100V

           TIP3055  SOT-93 case Vcb = 60V

           MJE3055 TO-220 case Vcb = 70V

Amanda

[nweeks]

Yep, Vcb breakdown will pop them alright...I'll think about that later..

My main question is, has anyone put PVC or Polymer blades on an FP motor?

I like the look of the ones from ecoinn.co.nv too - serious taper down to a thin blade - it'd have to be a strong co-polymer/carbon mix to handle the bending forces...

What's the best for an FP motor:

a profile like Jerry's 'Mike mod' blades, or the tapering ones from ecoinn.co.nz...

(Please don't say wood - I like the idea of plastic soooo much!!)

The electronics can wait, it's the blades I'll be making first...

(Thanks Amanda - you have some serious knowledge there!)

[nweeks]

I've been thinking of how to file down the corners, but the idea of using a hand file makes me cringe.

So, what if I clamp my 'millsaw bastard' file in my electric jigsaw(instead of a cutting blade), set it on a slow speed, and with gentle pressure on the end with my fingers, let it oscillate back and forth over the laminations...

Dunno...

Nige.

[BT Humble]

I've been thinking of how to file down the corners, but the idea of using a hand file makes me cringe.

Why are people so afraid of using hand tools these days?

BTH

(But what would I know, I'm looney enough to spend a weekend excavating 15 tonnes of dirt with a shovel).

[Jerry]

Hi Nige

The blades at ecoinn are the Hornet blades. I own and fly a 6 blade Hornet. The Hornet blade is an exact copy of the SW-403 blade. The only diferance is its slightly larger.

SW uses 3 Hornet uses 6. Id be willing to bet they're cheaper direct from Hornet.

I wish I had a 24/7 web cam pointed at the 13 gennys on the roof of my store (see airheads below). You could see the Hornet not spining much and my plastic blades spinning alot.

The 403 is the last to start spinning next to last is the 6 blade Hornet. All of my plastic blades are spinning well befor ther Hornet and 403.

Read the reviews here on the 403 and also on Hughs page.

If you need some startup tourque that blade won't cut it. Its designed for car alternator type gennys. Thats what a Hornet is and the 403 is very close the same. As such these machines need very high rpm. A blade of any girth will not do the requiered  rpm of these car alts. Without the gith or cord these skiny pencel size blades have very littel reaction with low wind speeds and also have very little tourque.

The F&P needs the tourque and not the 2,000 rpm. I discribe the preformance of these tiny width blades this way. Hold up a pencel in a strong wind, now open an umbrela in a lesser wind, you'd better hang on to the umbrella.

                JK TAS Jerry