Saturday, October 20, 2012

Battery of Confusion

I hear a lot of people making comments about batteries that tells me they are confused over how batteries fit into their electric airplane power system.  I decided to do this blog entry to try to clear up some of this confusion without adding any more to the subject.

I hope to clear things up by relating an electrical system to an internal combustion system.

In a simplified internal combustion system the gas tank stores energy (in the form of gasoline), a carburetor controls the flow of energy to the motor, and the motor converts the energy into mechanical motion.

In our electric airplane power systems, the battery stores the energy (electricity), a speed controller feeds that energy to the electric motor, and the motor converts the energy into mechanical motion.

The battery as two parameters that it is rated by, the voltage and milliamp hours.  The milliamp hours is a rating of its capacity, just like a gas tank capacity might be rated in gallons.  A higher number of gallons does not make a car go any faster, it only allows the car to run longer.  The same is true for batteries.  A larger milliamp hour rating will not make your plane fly any faster, only run longer.  There is another little mix to this in that the milliamp rating (multiplied with the "C" rating) is related to the flow rate.  This is similar to a gas tank with either a low or high capacity fuel pump and line.  If an internal combustion engine requires more fuel than than the fuel pump and line can supply, its power and performance will suffer.  So too, if an electric motor demands more current (milliamps) than the battery can supply, the battery voltage will drop along with the electric motor power and performance.

The voltage rating is a little different and is more closely related to the octane rating of gas.  If I have a high performance car motor and run regular gas in it, I can only expect so much performance.  The fuel mixture is only capable of creating an explosion of so much to push the pistons down.  Now if I put high octane racing fuel in the tank, I can expect much more performance.  This fuel mixture is capable of a much greater explosion to push the pistons down.  A low voltage battery can only give its rated voltage to the electro-magnets that repel the permanent magnets.  A higher voltage rated battery will allow for a larger repelling force.

Now, keep in mind, just as the internal combustion race motor is built to take greater stresses, if a batteries voltage is increased, the speed controller and electric motor must be built to take on the extra stress.

I hope this analogy will help those out there that have been confused about batteries and their voltage and milliamp ratings.

Thanks for stopping by my blog.  Please feel free to post comments, good or bad, and be sure to come back and check for future posts.

Tuesday, October 16, 2012

Wild Hawk Flying Fun

This post will be a double post as this post will serve both my Wild Hawk blog and RC Flying Fun blog.  How you ask?  Well, I found a new place to fly and I flew my Wild Hawk for my first outing at this location.  This is also the first time flying for me in several months.  Wow, a person can sure get rusty!  This new location is on a road stub near an abandoned mall construction site.  This road stub is off of the main road and across from the abandoned mall.  It is also surrounded by farm land used for growing hay.  There is a small group of flyers that get together each Sunday at this location.  One of the best features of this location is that it is only about ten minutes from my house.
why did I pick a place like this instead of a formal club with a real runway and amenities.  Well, I already joined the AMA (I recommend this membership for everyone in this hobby) and money is really tight right now (you folks with kids in college know what I'm talking about).  So funding my hobby and paying club dues and AMA dues is out of the question.  This site fits my budget and still gives me a good group to associate with.
Any way, here are some photos of this location including pictures of my Wild Hawk airplane getting ready to fly.

I did have an accident and crashed hard after failing on an outside loop.

It looked bad but I was up and flying again after some minor repairs and a battery swap.

I flew all three of my batteries this day.  The only unfortunate thing was that on this day there were no other flyers that showed up.  I had a good time anyway and could fly and land anywhere I pleased.

Before publishing this post I got a chance to fly again and made a video from one of my flights.  Enjoy this areal look around.

Thanks for stopping by my blog.  Please feel free to post comments, good or bad, and be sure to come back and check for future posts.