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My First Foray into Electric Powered Radio Control Model Airplanes

May 05, 2015



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Airfield Models (http://www.airfieldmodels.com/)My First Foray into Electric Power

I have just converted a glow powered radio control aircraft, Bride of Gonzo, into my first electric power aircraft.  I know very little about e-power, so please do not e-mail me your questions about it.  Frankly, I am not qualified to give you any answers at this point.

There is a video on the page linked above if you would like to see how the plane performs with electric.  Unfortunately, I don't have any video of when the model was glow powered for comparative purposes.  I may convert her back temporarily to do that, however.

The first part of this article discusses my perceptions of electric power vs. glow engine power.  Keep in mind that was when.  My attitudes have changed dramatically in a positive way.  In other words, if you're an advocate of electrics, please don't read the first few paragraphs and assume this is another bashing of electrics.  Keep reading.

I'm sure there are others who have the same impressions.  If you are a die-hard glow engine person, you might find some of my recent experiences enlightening.  My conclusions regarding electrics have surprised me.

 
 

Then

I have never been one to affiliate myself with various factions.  I simply decide at each juncture what will work best for me.  In the case of powering model aircraft I have always flown glow powered aircraft.  Glow has been a better choice for me.

In the mean time, I've kept an eye on what's going on in various aspects of the hobby to include things that I have absolutely no involvement in.  I just like to know what's going on and what I can draw from others that will help me build better models.

One of the things I've been casually paying attention to is electric powered planes.  Until recently they have had no appeal to me for many reasons.

Right or wrong, the following have been my perceptions of electric powered model airplanes based on what I've read and observed.

  • Motors, Batteries and Speed Controllers are expensive.
  • Battery Chargers are really expensive.
  • Extra hatches and cooling needed which add weight while decreasing strength.
  • Performance is far below what the same plane would be with glow power due to battery weight.
  • Significant power drop-off throughout flight.
  • Short flight times.
  • Having to remove hatches to pull batteries out between flights.
  • Waiting for batteries to charge.
  • Each new installation is experimental which often means more equipment is purchased (motor, battery or speed controller) before the airplane performs well.

One of the reasons I never got involved with electrics was comments like, "... and with this state-of-the-art equipment costing only $$$$$, we can now get flight times of nearly 6-8 minutes with nearly half of the flight having near full power available."

Every time I read something like that I laughed because my glow plane can fly as long as there's fuel and have full power available the whole time.

In order for a model to be successful with E-power, it needed to be very lightly loaded or experience short flight times.  The high weight of the batteries severely limited what could built.  Frankly, I haven't been very impressed with electrics.

One argument folks have made in favor of electrics is that they are less expensive over time due to not having to purchase fuel.  On the surface and with no further thought, that makes sense.  However, the airplane I converted went from having a .15 that could run 20-40 minutes on 3 ounces of fuel to a speed 400 with a 3-cell Li-Poly pack.  The Li-Poly pack cost nearly $100.00 - roughly the cost of 5-10 gallons of fuel depending on how much you pay for fuel.  And that still doesn't include the cost of the motor and speed controller.

On the low end of 5 gallons and 20 minute flights, that comes to roughly 64 hours of flying.  The bottom line is that I think the cost benefit thinking of electrics is not only wrong, but a moot point as well.

On a cost and equipment basis, here's what's required:

Glow

  • Engine
  • Engine Mount and Hardware
  • Fuel Tank and Lines
  • Throttle Servo and Linkage
  • Radio Battery
  • Glow Driver
  • Fuel
  • Fuel Pump

Electric

  • Motor
  • Motor Mount and Hardware
  • Speed Controller with BEC
  • Combination Motor/Radio Battery
  • Field Charger and Power Source

Of course there are solutions to a few of the problems associated with electric flight.  You could buy multiple batteries and always have one on charge so that you never have to wait.  There are less expensive chargers available, but if you seriously want to fly electrics than you might as well buy a good charger which can run into hundreds of dollars.

Likewise, you could purchase less expensive motors, batteries and speed controllers, but that only makes a poor system worse.

It's Not All Bad

Electrics have a lot going for them as well.  They are cleaner, quieter, environmentally friendly (at least at our end - who knows what goes on at the factories that make the stuff).  Personally, I really like the not tinkering with engines part as well as the not having oil and gunk all over me and my planes part.

Arguably the most important benefit of electrics is fewer noise complaints made against us.  As our world becomes more and more insanely over-populated, finding and keeping places to fly has become increasingly difficult.  It used to be that I could fly on the sports field of any local school.

Our legal system has created an environment where everyone feels they must protect themselves which means flying at schools or other large privately owned open areas has become a thing of the past.  No one wants to risk a possible lawsuit.

The point being that anything that helps us keep our fields or find new ones is a good thing.

 
 

Now

Ever since I entered this hobby there has been a driving force to develop electric powered model aircraft.  At first it was a grass-roots movement that had little support and required an extremely dedicated person to achieve success.

There has been considerable progress over the years, but the fundamental problem never changed - battery weight.  You simply can not take a plane that would weigh 3-1/2 lbs with a glow engine and put 3 lbs of batteries in it and have the same plane.  So again, we're back to flimsily built models to remove weight where we can or we're flying Telemasters.

But what we couldn't do is get a 12-15 minute flight in an electric Sig Kougar and have the same kind of performance as we had with glow.

The introduction of Lithium batteries has changed that.  When I converted Bride of Gonzo from glow to electric the weight remained roughly the same and I would say the electric motor is actually more powerful.  There is a significant difference in climb now.  Additionally, the 3-cell pack gives me 20-30 minutes of strong power.

Bride of Gonzo weighed 31 ounces ready-to-fly with a glow setup.  In addition to converting the plane to electric, I also added a proper landing gear.  The plane now weighs 34 ounces.  That is a slight increase, but the last time I weighed the model was before a crash so some weight may have been gained in the repair.  The new gear also weighs over an ounce more than the axle assembly previously used.  My best guess is that the electric setup added no more than 2 ounces of weight.  Contrast that with nearly a pound more if using NiCad batteries.

With NiCad's and Nickel-Metal Hydride batteries, there was a power fall-off throughout the flight.  With Lithium's, I'm seeing good power throughout the flight and then a sharp drop-off at the end.  What that means is I can do anything I want for most of the flight rather than doing all the power-hungry maneuvers at the beginning and forgetting about them for the rest of the flight.

My personal opinion is that if you have the money to buy high-end equipment for electrics than you can have planes that are on par with glow right now.  The technology has arrived.  Unfortunately, good equipment is still very expensive, but if it is like other technologies, the price will drop as more people adopt it and more manufacturers produce it.

What I foresee in the future is that electric power will surpass glow on a power to weight basis.  I believe glow power has reached a point where power increases will be very slight.  The technology has peaked.

Electric, on the other hand still has a long way to go.  It can only get better.  I foresee even better and lighter batteries that have higher capacity.  Motors will become more efficient and us guys who show up at the field with glow powered planes will be snickered at for being old-fashioned traditionalists.

 
 

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Copyright 2004 Paul K. Johnson