By Wayne A. Diercks – 4/27/2015

Intro

Have you ever wondered if flight performance of the SYMA X5C-1 quadcopter could be improved through lubrication?

Since the coreless motors themselves are sealed and the shaft from the propeller to the large main gear is essentially inaccessible, this leaves only the meshing of the two plastic gears to experiment with lubrication.

These plastic or nylon gears already appear to be very efficient. But, I (and others) have always wondered if some form of lubrication could noticeably improve performance. However, for me the number one priority is “do no harm”. That means that only dry lubricants would be considered since wet lubricants attract sand and grit.

String Hover Test Parameters

In a previous article of “Battery Flight Times for SYMA X5C-1 Quadcopter”, I detailed a consistent and scientific method of comparing flight times. In summary, I tied the quadcopter to a brick using wax kite string to just barely hover indoors (garage) about 6 feet off the floor. I was then able to make valid comparisons by timing each flight with a stopwatch. I had two identical quadcopters for these tests that I flew in the “naked” configuration where the prop guards, landing skids, camera and battery door were all removed. Using the same battery in all my tests to insure accuracy, I found that both quadcopters flew for 9 minutes and 50 seconds in the “naked” configuration (no prop guards, landing skids, camera or battery door) before any lubrication was applied. If a method of lubrication worked then flight times should increase significantly.

The Contestants

In my quest to find different types of dry lubricants I narrowed the field down to three graphite-based lubricants and one wax-based lubricant. Before applying them I decided to spray each of them on a similar plastic to that of the gears. I found that my nearly new recycling bin cover matched quite well while providing a good background color to perform a visual test of their properties after application.

It is a good thing that I did since the Lock-Ease Graphite Lock Fluid on the far left never did dry as advertised. It merely had graphite flakes mixed with an evaporating carrier fluid so that it could be sprayed from an aerosol can into a lock or other crevice. This carrier fluid never completely dried as can be evidenced by the runs and by my horizontal finger smudge the next day as shown in the photo. So, this product was eliminated from further testing. Do no harm.

The Powdered Graphite Lubricant in the puff tube differed from the rest as it is applied and remains in powdered form, which has no adherent properties in my opinion and probably falls off almost immediately. I had experience with this product (as did many parents) in preparing Pinewood Derby racecars in Cub Scouts. Applying the graphite to the axles just before each race produced a gray colored racetrack in no time.

The Blaster Graphite Dry Lube can best be described as gray graphite paint. It acted just like paint and dried in just minutes when applied in a thin coat. I found this product at Home Depot while looking for a similar product made by CRC, which I never did find.

The DuPont Dry Film Lubricant on the far right was a whitish, waxy liquid that dried fully after a couple hours. It ran some at first but later retained a dry, waxy coating on everything it contacted.

I decided to apply each lubricant to the gear teeth using an artist paintbrush since spraying from the can would get all over everything, ruining the looks of my white quadcopter. Furthermore, I decided to carefully mask each of the four gear modules and even the face of the main gear to further prevent a messy outcome. This required a great amount of time and painstaking work. Do no harm.

The end result was the entire small pinion gear received lubrication but only the teeth of the main gear did due to the masking. Once again, I did not attempt to lubricate any other components due to difficulty reaching the gear shaft and the sealed motor case.

Test Results

First, I applied the DuPont Dry Film Lubricant to quadcopter number one. This was the product that I was really pulling for to win the competition since it is relatively harmless, being a whitish clear wax and being easy to apply with little mess. Do no harm. After allowing overnight to dry, I performed my string hover test. The result: 9 minutes and 50 seconds. There was no discernable difference although I perceived that the quadcopter ran a bit quieter. Possibly, it was the “placebo effect”.

Then, I applied the Blaster Graphite Dry Lube (gray, graphite paint) to quadcopter number two. This was the product, which I felt had the greatest chance of success. It required a bit more care to prevent discoloration of nearby parts. The result: 9 minutes and 40 seconds. Certainly there was no performance improvement although once again I perceived that the quadcopter ran a bit quieter.

Just to be fair and complete, I then applied the Powdered Graphite Lubricant (again masked and with an artist paintbrush) to quadcopter number one after many flights in between to wear off any remaining wax from an earlier test. I always felt this product had the least chance of success since I believed that it lacked any method of sticking to the plastic gears. Even so, any graphite that clings to other parts of the quadcopter will show a gray discoloration so care of application was needed. Do no harm. The result: 9 minutes and 40 seconds. Again, nothing to write home about. After the flight the gears were less gray than before indicating that most of the powdered graphite had probably fallen off as predicted.

The Winner

So, the winner is: Compressed Air!

Yes, it has been said by someone wiser than me that, “the only lubricant that should be used on plastic gears is compressed air.”

A can of compressed air and a toothbrush for use before the first flight of the day is the best preventative measure to keep sand and grit from clogging the gears. Along with inspection before each flight, they will add longevity to the delicate, coreless motors powering the gears and provide greater enjoyment for years to come.

Conclusion

Sometimes in research we do not get the results we want. I spent the time and effort and believe that I covered the gamut of possibilities to a “solution without a problem.” Still, it is comforting to know that the plastic gears in the SYMA X5C-1 are as good as it gets. You can’t improve on perfection.