We ran some performance tests on our finely tuned Johnny Astro using our own power supply as a power source.   In all tests, the space vehicle was equipped with a landing carriage and astronaut however no capsule was used.  The results might surprise you!

Maximum Altitude - 44 inches

A maximum altitude of 44 inches was achieved with the space vehicle directly over the fan.  The measurement was taken at full throttle, measuring from the ground to the middle of the balloon.  In a test using a different Johnny Astro launching station, the space vehicle reached an altitude of only 36 inches.   

The superior performance of our first launching station could be due to a recent tune-up.  The other launching station may improve over time with added use.  Lack of use tends to oxidize much of the electrical parts of old toys, especially DC motors.  This can depreciate the performance or even keep it from working entirely.

Maximum Distance - 55 inches

With full throttle applied, the space vehicle reached a maximum distance of 55 inches.  It did however retract to about 51 inches only seconds after maximum distance was achieved.  With a steady hand, you could lower the altitude to try to gain a bit more distance.  It is interesting to note that the maximum distance was achieved with the "autopilot" in place.  The distance we achieved exceeded the specifications that Topper claims.  In their instructions, a range of 3 to 4 feet is given. The apparent improvement could be attributable to our power supply which closely emulates a new set of alkaline batteries which perform better than carbon batteries.  At the time that Johnny Astro was available, only carbon batteries could be bought.  Our second launching station did not perform as well, reaching a maximum distance of just 44 inches.  The reason is likely the same as we explained in the Altitude test.

Minimum Angle - 24 degrees

We measured the minimum angle that you can fly the space vehicle without loosing control.  In the test, the measurement was taken from the middle of the fan's front face to the middle of the balloon as shown in the "distance" picture above.  We found that the minimum angle is achieved with very little throttle applied.

Current Draw

At full throttle, the DC electric motor will typically draw 500mA.  The range of current draw that we have seen is between 400mA and 850mA at full throttle.  We have found that this large variation is mostly due to how well the motor is lubricated and how worn the motor is.  Excessive wear and a lack of lubrication causes the motor to work harder, thus increasing its current draw.


Johnny Astro was designed to operate from 4 D cells whose series nominal voltage is 6 Volts.  In reality, both carbon and alkaline batteries have a nominal output voltage above 1.5 Volts.  Depending on the age and condition of the battery, the output voltage can be 1.6 Volts or more per battery.  As a result, four D cell batteries in series can have a measured output voltage of as much as 6.5 Volts.  The voltage will be the highest with no load applied.

If you are not getting the same performance that we are, there could be a number of reasons;

Low batteries
Even new batteries can be depreciated due to sitting on the shelf.  Alkaline batteries have the greatest shelf life but still depreciate 3% each year.

Carbon Batteries
Use alkaline batteries instead of carbon batteries.  Carbon batteries have only a fraction of the capacity of alkaline batteries.

Motor Needs Lubricating
The first thing to do with any old battery operated toy is to lubricate the motor bearings.  Never use WD40.  It will gum up the bearings and ultimately seize them.  Use a good quality oil such as those made for inline roller skates.

Motor Needs Brush Cleaning
The motors' internal brushes can become oxidized over time due to non use.  Running the motor cleans the brushes.  Sometimes the motor will appear to be blown because it won't start, runs erratically or runs very hot.  If the motor will not even start, manually spin the motor till it runs on its own.  If it runs slowly or erratically, carefully apply the throttle ensuring the motor does not overheat.  This may be difficult to monitor since the motor in Johnny Astro is encapsulated.  To be safe, only run the motor for 15 seconds at a time until it runs smoothly. If the motor does not appear to overheat and runs smooth,  apply full throttle for 30 seconds at a time.  You will likely hear the motor increase in speed as the brushes clean up.  If you have a collection of battery operated toys, the best way to maintain those toys is by keeping them lubricated and run them once in a while.  If you are still unhappy with the performance, you can purchase an original replacement motor here.

Oxidized Rheostat (Throttle Control)
People often complain of "dead" or "weak" spots.  This is easy to fix.  Click here for details.

Propeller on backwards
This may seem strange but the fan unit will still move air forward even if the propeller is on backwards.  If you find that the balloon will only fly about 10 inches or so, reverse the propeller.  It is better to replace the propeller so that it is as far away from the motor as possible.  This improves the air flow.

Oxidized Battery Contacts
If excessive resistance resides on the battery contacts, the toy may perform poorly.  Take #400 sandpaper and clean off any oxidation.