Sunday January 28, 2007

Throttle Control for your 1/32 Scale Model Race Cars

You may wonder if anyone really knows anything about throttle control for 1/32 scale model slot cars.  We wonder too.  It’s frustrating because there are countless articles and internet discussions on this topic but nothing that really explains the topic thoroughly. There is a lot of information but very little that is actually specific enough to be useful. Of course you can spend a lot of money on expensive equipment but do you really need a $150 power supply and a pair of $100 controllers for your $200 race set? The answer is no and we will show you what is really needed and explain why.

Throttle control is a very important topic. The lack of good throttle control is a common problem with the hobby and it is probably the greatest issue facing people entering the hobby.  Many people may not experience good control and encounter frustration attempting to obtain it, even for long-time enthusiasts it can be a difficult issue to resolve. This is a very complex topic; there are a number of inter-related factors that make this topic very confusing.  Many have figured out their own unique way of dealing with these issues but it may or may not be applicable for other people to use these unique solutions.

This article is intended to illustrate what a novice or returnee to the hobby would need to enjoy racing 1/32 scale model slot cars.  The intention is to show how to provide good throttle control for a home racing track without breaking the bank.  This is NOT intended to determine what may be the absolutely best controller available.  Most racers are accustomed to providing their own controller and they often spare no expense to obtain the very best but we feel that throwing money at the latest equipment is not appropriate for beginners.  Our recommendation is to provide identical controllers for each lane, this way every racer utilizes the same controller. This makes for a level playing field and makes it more attainable for beginners.

The intent of this article is to help someone gain good throttle control of their 1/32 scale slot cars by actually comparing the throttle response of different slot cars with a wide selection of controller resistances.  This way we hope to provide practical information on this topic.  It is NOT intended to be the ultimate for competitive performance, nor is it intended to make any one particular car faster.  Instead, we hope this will help novices achieve good throttle control so that they may enjoy our hobby.

Addressing this topic was an enormous challenge; this was a huge undertaking in terms of time, resources and creativity. But it was worth the effort, as the results of the different interactions between cars, controllers and power supplies are enlightening and occasionally a bit surprising.   We even had to develop a method for evaluating throttle control.  We then performed extensive testing to evaluate various control systems. The Home Racing World recommendations are a result of thorough testing and extensive analysis.

There are a wide variety of controllers available. This comparison is only for traditional resistance type controllers as these are the most affordable type available, also they have been around over forty years and are very durable. There is a lot to this topic and this is just the first part of efforts to clarify what is really needed to enjoy our hobby. There are electronic controllers available but they are not included in this evaluation.  We hope to evaluate some of the electronic controllers at a later date. The power supply is also a critical part of the throttle control equation and we also hope to evaluate at least one variable voltage units in the future.

The importance of good throttle response can not be underestimated. It is throttle control that makes racing scale model cars entertaining and challenging – not speed as many people think.  With good throttle control a novice can enjoy the hobby and it will allow them to experience less crashes and have a lot more fun.
 

Methodology

This evaluation was performed as if we were new enthusiasts entering the hobby.  A new race set was evaluated with the cars and set being run just as they are received.  Most enthusiasts then purchase additional cars so we evaluated the throttle control of various cars.  Then all of these cars were evaluated with various aftermarket hand controllers and finally an aftermarket power supply was utilized.

First we had to develop a method for evaluating throttle control.  

We had to answer the question; “What do we want from a controller?”

Our answer is that we would like to see a controller that provides a constant change in speed of the car for a corresponding change in throttle position throughout the complete range of throttle movement.  Some would call this “linear” response; others talk about wanting the response to be “smooth”. To be more specific we divided this into three characteristics; launch, initial speed and response.  Each of these characteristics are rated good, marginal and poor, the ratings are also color coded with simple “traffic light” labeling; green for good, yellow for marginal and red for poor.  Listed below are each characteristic along with a definition of their ratings.

_______________________________________________________________________________

Launch - With the initial movement of the trigger (or thumb plunger) we want the car to start moving, we do NOT want to apply half throttle to get the car to move.

            G   = Good if the car moves before ¼ throttle is reached

M   = Marginal if the car starts moving after ¼ to ¾ throttle

P   = Poor over ¾ throttle (this is the “on/off” switch phenomenon)

Initial Speed - Once moving we would prefer to have a throttle position just off the closed position that allows the car to crawl around the track at a very low (& controllable) speed.

G   = Good; slow controllable speed, will go all the way around track

   without releasing the throttle

M   = Marginal; must let off to go around some corners

P   = Poor; fast, will need to constantly “blip” the throttle to negotiate

               any corners.

Response - We want throttle response to be proportional to position – a crawl or low speed at ¼ throttle, at half throttle we’d like to see a more speed, at three fourths throttles even more velocity is expected and at full throttle we’d like to have a noticeable increase over ¾ throttle position.

G   = Good; continuous change in speed with throttle position

M   = Marginal; flat response, some changes in throttle do not change

   speed

P   = Poor; one part throttle speed, which can be slow or fast, and full

   throttle.

_______________________________________________________________________________

This is a simple and repeatable evaluation.   You should be able to do this yourself on your own track and cars.    Please note that only subjective control was evaluated.   We are not concerned with such items as top speed and we did not measure lap times.   Don’t worry improved control will of course help with lowering lap times but it was not considered in this evaluation.   More importantly improved throttle control will help with lap to lap consistency.   In other words, this is not about making any particular car faster, that might be an indirect result, but it is not the main reason for this testing.    Cars were evaluated one at a time and not under side by side “racing” conditions.

There are also some characteristics that were not rated in our evaluation such as the feel of a controller; the weight, balance, ergonomics and other intangibles were not evaluated.   There are other factors such as long term durability which is way beyond the scope of this evaluation and we could not address.

Examples:

A) A car & controller combination that results in the car shooting away at the smallest movement of the throttle would be rated:

 Initial

Launch           Speed           Response

    G                     P                     P

This car could be driven around but only by giving the trigger short quick jabs of the throttle trigger and letting the car coast through the corners.   This is not really fun.

B) A car that moves before ¼ throttle and will creep along the track such that it will travel all the way around the track but has only a small increase in speed until full throttle is reached would be rated:

 Initial

Launch           Speed           Response

    G                     G                     P

This is the “on/off” switch type of response that many of us have experienced.

C) When your car does not move until half throttle, has enough speed that the throttle needs to be released to negotiate some turns but only has a linear response up to full throttle operation would be rated

Initial

Launch           Speed           Response

   M                     M                     G

This car could be driven around most tracks but would only be mildly satisfying to race with.

D) This car moves immediately with throttle movement and has an initial speed that is low enough to negotiate even the tightest turns, with more throttle movement the speed increases but at full throttle the car has a substantially more speed.

Initial

Launch           Speed          Response

    G                     G                    M

This is another car that can be raced but is not very rewarding because it is difficult to moderate the middle speed range.   This type of response can be good for a younger racer when a stop is installed to keep the trigger from reaching the full throttle position.

Equipment

Track

An Artin four lane race set was utilized for three reasons.  The first we already had a set to begin with and it saved us the expense of buying something.  Second it has a large quantity of high quality track included.  The third and most important; these sets provide the best introduction to the hobby because of the throttle control of the cars which are provided. These sets will allow one to quickly learn what the hobby should be about – having fun racing slot cars.

These sets are great when the Artin cars are utilized but when some of the other brands of cars are run the throttle control deteriorates, especially when cars with strong traction magnets are used.  When the various brand of track and cars are combined the performance may be marginal, this is a common issue of the hobby for all scales not just for 1/32 scale racing.

Cars

Five cars were used for this evaluation.  The cars were picked because we considered them “drivers” cars, cars that are fun to race. These cars are all different and they represent a good cross-section of the performance of 1/32 scale slot cars in use today.

The cars evaluated are:

• Artin Stocker – this affordable car has a motor with modest power and a chassis that provides good balance and traction even with a relatively weak traction magnet.  It is very fun to hang the tail out in a power slide & “drift” around corners.
• Ninco “Classic” Ferrari Testa Rosa – this car does not have a traction magnet, the NC-1 motor is responsive and with narrow tires it is very entertaining to drive vigorously around any track, it is a slightly faster version on an Artin car. 
• Carrera Ford Talladega – this is fast car with strong traction magnets which makes it like many current slot cars, but it is a big car that has a high center of gravity an with narrow tires must be driven with precision.
• FLY Viper – this is a very fast car with a very strong traction magnet which gives it tremendous road-holding capabilities.   Even with the strong traction magnet the throttle must be applied judiciously or the tail will swing wide when driven too aggressively.
• Vintage Monogram Ferrari 250 GTO – equipped with a classic 16D motor this car has plenty of power, the low slung brass chassis means a low center of gravity but with no magnet and narrow tires it is fun and challenging to drive quickly.

Power supply

Stock Artin power supply – 13.6 volts/ 0.3 amps

Samlex 1203 13.8 volts with 3.0 amps

Controllers

This testing covers the traditional type of controllers that utilize a variable resistor to modulate the velocity and acceleration of your slot car.

The following traditional controllers were evaluated:

• Stock Artin Controller (note: no brake feature)
• Parma Economy controllers with 7, 15, 25, 35, 45 & 60 Ohm resistance. The Parma controllers were evaluated with the brakes functioning; a short explanation of this dynamic braking feature is included at the end of this feature.

Installing these Parma controllers and the after market power supplies on the Artin race set was a “Do It Yourself” type of installation process.   We cut-off the plugs of the Artin controllers and power supply and used these plugs to connect to the Artin power base.  Some additional wiring was done to attach the brake wire from the Parma controllers to the power base.  This was not difficult and this information can be found elsewhere on Home Racing World.  Additionally some of the on-line slot car vendors can provide this as an extra cost service.

Results

We found that when all of the control characteristics are rated “good” (green) then racing slot cars is a lot of fun, even when alone.  Having the ability to precisely control the speed of a car through a tight turn or power sliding through long curves was challenging and fun.  We just didn’t want to stop when all three characteristics were rated green.  Not only was it more fun with all three characteristics green but we also noticed that crashes and de-slots were greatly reduced too.  We would reel off a number of laps when we were all “green”.

Stock Artin Power Supply & Controller

The stock Artin power supply and controller functioned very well with the Artin cars.  We found that we had good control of the speed of the Artin car and we could complete a lot of laps at a rapid pace without the car coming out of the slot.   It was very fun!   From experience we know it is easy to have side by side by side racing with these cars even with beginners.

Then we evaluated the other cars with the power supply and controller that was supplied with the set.  The NINCO Ferrari TR was very similar to the Artin car; it had good control and had just a bit more top speed, it was a great deal of fun.

The other three cars did not have the throttle response we would like to have.  The Carrera, FLY and Monogram cars all started moving with just the slightest throttle trigger movement with an initial speed that was very low and controllable.  But the throttle response left just a bit to be desired.  The slow and medium speeds control was adequate but the mid-range and up control was lacking.  The speed variation from ¼ to ¾ throttle positions did not quite have the change in speed we desired and then at full throttle the speed increased dramatically.  The cars could be driven around the track with decent control but it just a bit tricky to drive these three cars fast through long sweeping turns.  We rated this throttle response “marginal”.  These three cars were not as much fun as the Artin and NINCO cars.

There was a very noticeable difference in the top speed of each car. The FLY Viper was extremely fast. The top speed of the Carrera car seemed very fast too but it was not as fast as the FLY Viper.  The NINCO and Artin cars seemed to have a little lower top speed than the Carrera but were pretty even with the NINCO seeming to be just a bit quicker than the Artin car. The top speed of the vintage Monogram car seemed to be in about the middle of this group.

The cornering of each car was also vastly different.  The FLY Viper could take turns at a fantastic rate of speed without de-slotting or crashing, when over-driven the tail would swing wide but not de-slot.  The Carrera car was very different and needed a different driving style, it needed to be slowed down well before a turn, only then the throttle could be used to power it through a turn.  The Artin, NINCO and vintage Monogram cars had somewhat similar characteristics; as they could be driven in long power slides even on slow turns.

Our five cars drove quite different from each other.  What would it take to have a good level of control for all of the cars?  Or is this even possible?  So we tried a number of Parma controllers with a wide variation in resistance.  

Parma Controllers with Artin Power Supply

Overall the 60 ohm controller had response very similar to the Artin controller and we would surmise that the Artin is pretty close to a 60 ohm controller.   The Parma 60 ohm controller was good with the Artin and NINCO cars.  The response with the Carrera, FLY and vintage Monogram were rated marginal.  

The 45 Ohm controller was good for all of the cars.  All of the cars would start moving with very little throttle input and the initial speed was controllable.  The throttle response was good throughout the travel of the trigger.  The cars could be driven rather vigorously through the turns, some cars in power slides on the larger turns.  This is the throttle control we wanted to achieve.  It was fun to reel off a lot of laps with all five of the cars.

The 35 ohm controllers also provided good control for all cars tested.  The cars started moving almost immediately with the initial trigger movement and could be driven around the track with a lot of control at all speeds.  The response from ¼ to full throttle saw a linear change in speed with the movement of the trigger.  It was addicting to run any of the cars with this controller.

Both the 35 and 45 ohm controllers have ratings that are all “green”.  Are there differences between the 35 and 45 ohm controllers?  If we really looked for differences, yes, we could find some slight differences but they really were not significant enough to affect the ratings.  Both the 35 and the 45 ohm controllers are good choices.

With the 25 ohm controller we found that the initial speed of both the Artin and NINCO cars was a bit too fast to negotiate most turns. We found ourselves blipping the throttle to get through some of the turns with these two cars; therefore we rated the initial speed “marginal”. The vintage Monogram was really good with this controller and the Carrera and FLY cars are rated good for all three characteristics.  

With the 15 ohm controller we rated the throttle response of the Carrera and FLY cars “marginal” because it seemed like full throttle speed was reached just past ½ throttle position. The Artin and NINCO cars again exhibited high initial speed. The vintage Monogram seems to like this controller and was a lot of fun.

The 7 Ohm controller performed unacceptably for all cars in all three control categories; launch, initial speed and throttle response.   All of the cars seemed to receive full power as soon as the trigger was moved. They could only be driven around the track by giving the trigger short stabs.

Generally as the resistance of the controller is lowered the affect on our three characteristics were as follows:

• Launch is sooner, it will take less throttle travel for the car to start moving.
• The initial speed is usually higher.
• The throttle response was mixed as the resistance is lowered, it may or may not be improved, and it’s apparently one of those things that “it just depends”.

Note - The ‘brake’ feature was utilized for this testing (see the appendix for a brief discussion on brakes).  This did not affect the control that we were measuring but it was noticeable.  We found we could hold full throttle longer, in effect drive “harder” into the turns.  For more detail on this feature see the additional comments section at the end of this article.

After-Market Power Supply with Artin & Parma Controllers

The results were very similar to the Artin Power supply but this is deceiving.  The cars were not noticeably faster with this power supply, the voltage measured was almost identical to the Artin power supply.  The reason you would want this power supply is for the additional amperage.   In simple terms the Samlex has identical voltage to the stock Artin power supply but it has more amperage.  The higher amperage will maintain the voltage at a constant level.  The results were identical to the Artin power supply.  The evaluations summarized here are of cars being run individually.   The difference between the two power supplies is the amount of amperage that can be provided.  When the power supply can not provide the amperage demanded the voltage drops thus affecting the speed and control of the car.  This is not noticeable when racing the stock Artin cars but it is when using other cars with strong traction magnets (cars which need more amperage).  The insufficient amperage also means the electrical draw of one car can affect the car(s) in other lanes.  The cars are drawing more current (amperage) than the power supply is capable of supplying.  One car on the track runs fine but when a second one is added you may notice the cars slow down or are not responsive to throttle changes.  This can have a dramatic effect when one car stops or comes off of the track, then the car remaining on the track gets more power and ends up flying off the track too.

This is noticeable when racing the Carrera vintage stock cars on an Artin track with the stock power supply.  This issue can be resolved by increasing the amperage available.  Many people purchase two Artin race sets and the second stock Artin power supply can be utilized to resolve this condition.  We know because we tried it. Also, the additional amperage of the Samlex  power supplies also correct this condition.