Multiple Gear Ratios for KidWind Nacelles

 Did you ever design a set of blades, attach them to your turbine hub, place it in the wind tunnel and not have the blades turn?  Could the resistance in the gear ratio be to high? What to do? Read on...

Here is a picture of my first modification to the original KidWind Nacelle. Drilling holes for two brass tubes through which axles are ran so a two step gear ratio could be built.  This two step ratio allows for ratios of 1:16 and 1:32 using the existing KW 16 T, 32 T, 64 T and 8 T generator pinion. The purpose if this was to increase the rpm to the KW generator and produce more electricity. Mission accomplished!

Then I thought, what if...

I sawed off the bottom section on one side of the Nacelle and mounted a couple of metal guide rods. On these guide rods would slide an Upper and Lower Guide with set screws to lock them in place. The adjustable Upper Guide would hold the axle for the middle set of gears. The adjustable Lower Guide would hold the KW generator.  The first step, green gears  (8 T pinion and 64 T ) would be a 1:8 ratio and always stay this way. The yellow 16 tooth gear would always be stacked on the middle axle shaft but the white top gear would be changed out to get any different gear ration between 1:8 and 1:32. The idea here being that perhaps there would be some value in being able to more finely adjust the gear ratio between the blades and the KW generator and get more electrical output?

So I went to work with my 3D printer and proceeded to make gears with 56,  48 and 40 teeth to fill in some of the ratio gap between the now possible 1:16 and 1:32 ratios using the green KW 64 and 32 tooth gears. 

Note: I also printed off gears with 28, 24, and 20 teeth to fill in the gaps between the now possible 1:8 and 1:16 ratio)

So hear is a picture showing the set up for a 1:32 ratio ( 8:64 x 16:64 reduced to 1:8 x 1:4 then to 8 x 4 = 32 for the final two step ratio 1:32) which is now possible. Note: the Nacelle needs to be modified plus you need the two rods and Upper and Lower Guides. Changing out the top main shaft gear connected to the rotor blades with any of the new gears now gives you 6 new ratios.

Here is the wind tunnel setup for 4 m/s. The shroud for high speed is hinged on the right side and open.

I decided to test out the new adjustable gear ratio design and to see if it would hold up and if changing the ratios would result in more electricity output from the 2 watt KW generator. I would test two different rotors. One with 3 blades and one with 6 blades. The size of the blades (NACA 2024   400 mm long with a 70 mm chord) would be the same for both. The pitch of the blades was set at 15 degrees. The rotors would be tested in wind speeds of 4 m/s and 7 m/s. And electricity output from the 2 watt KW generator would be measured in Joules with a 30 ohm load for 30 seconds.

With the shroud swung shut the wind speed increases to 7 m/s and makes a significant difference in wind speed and force on the blades and gear train. Good test of turbine component strength.

Here is the data that I collected over the tests under these conditions with 9 different gear ratios.

Note: The data in yellow can now be produced in one step with the present Nacelle

The data in pink could be produced now with present KW gears and the New Nacelle with Up Grade Kit.

Conclusion: Changing gears to get multiple gear ratios is made possible and easier with this design change and additional parts. However, the impact to the electrical output with the 2 watt KW generator did not seem of value when compared to the existing 1:8 , 1:16 and 1:32 gear ratios. More testing will follow with longer blades and higher wattage generators.

Comments and feedback is appreciated.

Dick Anderson

 

  

 

Micro Maple Syrup Cooker

Well looks like it has been several months since my last post. Have been enjoying log cabin #6 and the treehouse. Interesting to see the scenery changes from the treehouse as it goes from summer to fall to winter. Also have been learning 3D printing and making some parts for use with KidWind teams.

Although it is a bit early to be thinking about making maple syrup this project has been on my mind for a while to build a smaller version of the sap cooker I have used in the past to make maple syrup.   

You can see what I used in the past. That this unit is about 4' by 4' and made of several parts requiring assembly. For boiling off 400 gallons of sap to make 10 gallons of syrup (requiring 100 gallons of propane) this set up fit the bill. Then you have to consider tapping 25 trees, placing 50 sap bags and collecting 400 gallons of sap over a week or two and it becomes a job. Not worth the time and effort to just make a gallon or two. Where my idea now is just to have some fun and make a little syrup and be done. 

Enter the MMSC (Micro Maple Syrup Cooker) A friend and fellow maple syrup maker got some equipment from me a few years ago to give making syrup a try. When I saw his set up using a turkey cooker I got this idea. Menards had a sale on turkey cookers so I bought one for $100. Here you can see the turkey cooker set up on it's stand. To the right is the sap feeding system connected by a pipe to the cook pot. The sap feeding system is a metal box with a stock tank float in it. The green hose connected to the stock tank float goes up to the sap supply resevoir. The float is set so that the level of sap in the cooking pot will be about two inches deep. Keep in mind that a deep liquid requires a lot of heat an time to boil. The best boiling takes place when the liquid level is about 2 inches deep. To do this manually you would have to stay by the cooker and add a gallon of sap every 15 minutes. My friend can tell you what happens if you let the level get to low and the pan burn. Yeks! With my system as the level of sap boils off and goes down in the cook pot the float sinks, opening the valve allowing sap to flow from the reservoir keeping the level of sap in the cooker at 2" at all times. With a 30 gallon reservoir supply of sap you are good to go for several hours. Just light 'er up and let it boil. But don't let the reservoir run dry!

Here is a picture of the sap feeding system. In the connections between the cooker and feeding system is a shut off gate valve and union fitting 

(behind the green hose). The valve will stop valuable finished maple syrup (it take 40 gallons of sap to make 1 gallon of syrup) from coming out when the union is disconnected so the pot, with the finished maple syrup in it can be lifted up and dumped out for filtering and canning. Right now the system is sitting on a temporary base set up. A better more secure platform with a base will be made in the near future.

A look below the cooking pot shows the heat that is produced. First test run looks like I will be able to boil off about 6" of sap per hour of burn. Will be doing some more testing before the sap run this spring and work up some times and propane usage to share in a post then.

In the meantime I am just going to enjoy some nice home made maple syrup from last season on an egg pancake and think about the spring sap flow to come and using my MMSC to make some.