Roll 99 for the Duct Tape collection

 

Steve and Sandy K. Are world travelers and here is the list of countries they have visited and worked in. Each time they have worked tirelessly to seek out a roll of Duct Tape to add to the World Duct Tape collection. Each roll has a story and if you want to read about them check out my blog at ducttape2thefuture.blogspot 

This time Steve and Sandy were on a fun educational trip to learn about Mongolia. They flew to South Korea first. This gave Steve the opportunity to seek out a roll for the collection. Then they went on to Mongolia for a two week stay with a group of 10 like minded people to experience life there living in a yert! Getting a roll of duct tape was difficult until they were taken to the “Black Market”. This was sort of a very large area where many vendor gathered to sell and trade just about everything you can think of.

So Steve adds roll number 99 to the collection. Only 101 more rolls to go. I will be working of getting some national attention about the World Duct Tape collection in the near future . Keep watching.

 

The things I discover along the way

 KidWind is where a team of students put their minds and skills together to design, build and test a model wind turbine to see how many Joules of electrical energy it will produce in 30 seconds while running in a 4 m/s (8 mph) wind velocity. This is an example of some of the thinking that goes on during the process. 

Let’Look at the chart above showing the testing data collected.  

Here are some things that change when you adjust the resistance load on a generator.

- As the ohms of load in (black numbers) went up the generator rpm in (gold bars) went up. Why?

    The resistance is placed in parallel with the armature windings. This results in a lower resistance in the circuit. This allows the armature to turn faster in the same wind speed.

- As the generator rpm in (gold bars) went up the voltage on (green line) went up. Why?

    When the armature turns faster the wires cut through the magnetic lines of force of the magnets faster and this causes the voltage to increase.

- As the Ohms in (black numbers) went up the Amps on (red line) went down. Why?

    The Ohm Load is in parallel with the armature wire where the amps are being created. In a parallel circuit the amperage is divided over each resistance. Some going to the Ohm Load and some coming through the armature wire. There is a bit more to this that needs to be explained.  

- Most watts on top (blue line) was produced where the rpm in (gold bars) crossed the Amps on (red line) 

    Why? I am going to call this crossing point the “Goldie Locks Spot” Not to hot. Not to cold. Just right! Not to much resistance for the flow of electricity (electrons) through the generator armature wire turning through a magnetic field at this speed. Which is caused by this much wind velocity. 

So let’s look at what we know:  

Generator - 40 watt 12 volt dc

Generator Resistance - 6 ohm

Number of blades - 16

Blade material - 20 gauge galvanized steel

Blade size - 1.75”  (4.4 cm) root 6” (15.2 cm) tip 17” (43.2 cm) long

Rotor radius - 18” (.45 m )

Wind velocity - 4 m/s (8 mph)

Free spinning rotor RPM - 4500

Generator pulley - 1.75” diameter

Bicycle rim diameter - 17.5”

Belt - 5mm poly material

What happened? Let’s see…

30 ohms of resistance load was placed in parallel with the generators 6 ohms of resistance. The total load result was (R1 X R2) / (R1 + R2) = 5 ohm (Note: actual measured circuit resistance in test was 4.4 ohms) .

The rpm reached with this load was 3180. At this point data was collected for 30 seconds. The median voltage was 22.4 vdc and the median amperage produces was .753 Adc. Calculating watts as V x A this resulted in 16.86 watts times 30 seconds run time  = 506 Joules of electrical energy.

Comments and questions are welcome.

Dick Anderson

Wisconsin KidWind Advisor