Airfield Models - Model Aircraft Engines

How to Start and Run a Model Airplane Engine

January 21, 2009



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Airfield Models (http://www.airfieldmodels.com/)Starting a Model Aircraft Engine

It is surprisingly easy to start a model aircraft engine.  Some can be a little stubborn but for the most part any engine not past its prime can be hand-started in a couple flips.

Some engines lose compression when they are hot making them difficult to start immediately after they are shut-down.  In this case allow the engine to cool or use an electric starter.

Caution!  Some propellers have extremely sharp edges.  For your own safety scrape and sand this edge down.  If you try to flip the propeller by hand you will get a nasty razor cut.

Many people use a Chicken Stick to start their engines for safety purposes.  A Chicken Stick is a small, hand-held, rubber coated stick that is used to flip the propeller and keep the fingers out of the propeller arc.

 
 

Hand Starting a Glow Engine

My first recommendation for starting an engine is to attempt hand starting before automatically reaching for an electric starter.  It is faster and easier and not as hard on your engine.  Follow these steps closely and you will be amazed at the success you have starting your engines.

Before you attempt to start your engine ensure that:

  • Spectators are a safe distance away and behind the propeller.

  • There is nothing that can get pulled into the propeller.

  • The glow igniter is not connected.

  • The fuel tank is full.

  • The propeller is securely mounted using a real wrench not a four-way wrench.

If you have never run this engine before or for any reason think the high-speed needle valve is not close to the right setting then close the needle all the way.  Do not crank it closed or you might damage the spray bar.  Just close it until it stops.  Now open it about 2 full turns.  That should give the engine a sloppy rich setting.  You can lean (close) the needle a bit if it is too rich after the engine is running.

To Hand Start (almost) any Engine

1. Move the throttle to idle, hook up the glow igniter and turn over the engine slowly by hand.  If it kicks then skip to step 7.  If you do not feel a slight kick then disconnect the igniter and continue with the next step.
2.

Open the throttle all the way.  Put a finger or thumb over the carburetor to seal it.  Turn over the prop by hand you will see fuel moving up the fuel line toward the carb.  This is called choking.

Continue doing this until you see the fuel enter the carburetor.  After you see the fuel enter the carburetor give it only one more flip.  If you flip it more than once you will probably flood the engine.

3. Remove your finger from the carb and move the throttle to the idle setting.
4. Flip the propeller over sharply a half dozen times to get the fuel distributed throughout the engine.
5. Connect the glow igniter.
6. While holding the propeller, turn (do not flip) the engine over several times until you feel a definite "kick."  The kick means that it is ready to start.  If the engine is flooded then be careful when you flip the prop it may backfire and smack your hand pretty hard giving you a nice cut.
7. Give the propeller a good flip and it should start immediately.  If it does not start continue to flip the prop until it no longer kicks.  If it still does not start then disconnect the glow igniter and go back to step 1.  Once or twice through these steps only does not even take a minute and your engine should start.

Learn Something New Every Day

My Webra Speed .32 engine runs great and starts easily.  However, it has a vicious kick no matter how quickly I flip the prop and move my hand out of the propeller arc.  For that reason I decided to use my starter on this engine instead of trying to hand start it.

I was telling someone about this at the field one day and over walked Mike Phillips who said "Nonsense.  This is a great running engine and can be hand started every time in one or two flips."  As he started to turn over the engine I said, 'I will get out the first aid kit, Mike.'  He smiled, gave the engine a flip and it started right up without removing any of his fingers, dammit.

He did something that I had never even thought of before and I guess a lot of people know about it other than myself.  I normally flip an engine through compression in the direction it is supposed to run.  If the engine starts backwards consistently, then I flip it backward through compression.

Mike did not do either of these things.  He flipped the engine backward so it would "bounce" off compression rather than flipping it through compression.  I have been doing this with the Webra ever since and have not been bitten once.  Mike is right.  It starts in just a couple flips every time.

 
 

Using an Electric Starter

I think flyers abuse their engines with electric starters.  I have one and I use it with my helicopter because there is really no other way to start the engine.  My helicopter requires a starting shaft which replaces the aluminum cone on the front of the starter.

Whatever you do, do not keep cranking your engine with an electric starter if it will not start.  You are just wearing it out (the engine and the starter).  If the engine will not start then disconnect the fuel line and flip it until all the fuel is out of the engine.

If you think the engine is flooded (which it probably is if you've been cranking it with a starter) then you can use your starter to get most of the fuel out of your engine quickly:

  1. Disconnect the fuel line.  If you are using some type of pressurized system (muffler or pump) then plug the line.  It's a good idea to plug the line anyway so fuel doesn't siphon out of the tank.
  2. Remove the glow plug.  Place a rag over the head so raw fuel doesn't spray into your face.
  3. Turn over the engine for a couple seconds to blow the excess raw fuel out.

Sullivan Hi-Tork Electric Starter for Model Airplane, Car, Boat and Helicopter EnginesThat technique doesn't totally un-flood the engine but it gets most of the fuel out.  Put the glow plug back in and then connect the glow igniter.  Be sure the throttle is at idle and flip the engine over until it kicks over.  Reconnect the fuel line and the engine should start right up.

Remember, engines burn fumes, not liquids.  You only need a very small amount of fuel in the engine.  Most starting problems are either a bad fuel feed or a flooded engine.

Electric starters are a good thing, but they are really not necessary to start most engines.  I do recommend them while cautioning you that they can cause unnecessary wear on your engine.  The Sullivan starter sets the standard and is very good.

Sullivan makes several models. This is the standard starter that most modelers use.  Starters are made by other companies as well.  I am sure they all work fine, but I have not used anything but the Sullivan so you may want to ask around your field for other recommendations.

 
 

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Model Airplane Engine Glow Fuel
Setting Model Aircraft Engine Mixture Controls

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Copyright 2003 Paul K. Johnson