Electric Power Basics
By Lohring Miller
NAMBA Safety Chairman
Electric power plants have very
different characteristics from internal
combustion engines. The power from an
internal combustion engine can be
estimated by knowing the displacement,
average cylinder pressure, and rpm. An
electric power plant’s power can be
estimated from only the input voltage
and current. The definition of electric
power in watts is the voltage times the
current and there are 746 watts in one
horsepower. As an example of a 7.5 nitro
replacement power plant, a motor with
6S lipo batteries (22.2 volts nominal)
and 100 amps current draw is putting out
around 2.4 horsepower. That’s 22.2 x
100/746 x .8 (The system is at least
80% efficient in converting input power
to shaft power.) That system will drive a
7.5 size outboard tunnel at least as fast as
a modified 7.5 nitro engine.
Since rpm is not related to power,
how do you know what rpm your electric
motor will turn? That’s related to
another motor parameter called Kv. The
Kv is the no load rpm per input volt.
The above mentioned electric motor had
a Kv of 1100. That means the nominal
motor rpm is 1100 x 22.2 or 22,400 rpm.
PROPWASH
6
October 2011
Laissez Les Bons Temps Rouler
By Carlo Catalanotto
District Five Director
“Laissez les bons temps rouler”
is a phrase that I’ve heard since I
was a child growing up in the New
Orleans area. It was always around
Mardi Gras time that it would
really get mentioned a lot while
people where partying and having a
good time. For a long time it really
never meant much to me other then
just another Mardi Gras tradition. It
just seemed to blend in with the
crazy music, parades, and endless
parties that happen each year, and I
never really gave much thought to
the meaning. In case you have
never heard this phrase it is a French saying that when translated means “let the good
times roll”. Now that I am older and think about things a lot more then I did when I
was younger, that phrase just seemed to fit my thoughts on the races and people that
we have here in District Five. With the year halfway over our district has had quite a
lot of races already, and I can honestly tell you that they just keep getting better and
better. I feel so fortunate to be involved in this very special district where these guys
truly know the meaning of “Laissez les bons temps rouler”.
We have our biggest race of the year coming up in November, the “VooDoo Gas
World Championships” at VooDoo lake in the New Orleans area. This race is known
for having the fastest racers in the country duking it out each year for bragging rights
and the chance to take home a World Championship trophy. This is all done each year
live on the internet for everyone to see thanks to coverage by MeTime Productions.
This is the only race I know of where you can get restaurant style food served at the
race. The Fat Boys catering guys serve food each day at the concession stand that is as
good as most restaurants. They have New Orleans style dishes like fried shrimp,
oysters, Boudin sausage, gumbo, and jambalaya along with the normal hamburger, hot
dog, and french fries style items. The after hours festivities just step it up a notch as
we boil seafood and have a live band under the pavilion while people dance and enjoy
themselves to the music. I have to laugh every time I hear one of the people that have
attended this race say that this is just a huge party where a race breaks out. That just
leads me back to my original thought and theme for our district race in November
“Laissez les bons temps rouler” let the good times roll. See everyone at the races.
There is plenty of room for the cold pits with a
great view of the pond at the Voo Doo races
A beautiful Louisiana sunrise is the back drop before a day of racing at the Voo
Doo pond