For my Sbach 342 I decided to use a NTM Prop Drive 50-60 series motor. The NTM Prop Drive motors from HobbyKing tend to be pretty good motors. HobbyKing doesn’t tend to market them as their top end motor so when compare it to their “nice” motors it’s a good deal. When compared to even nicer motors like Scorpions or Hackers it’s a steal!
The NTM Prop Drive 50-60 360kv motor can swing a pretty big prop. According to HobbyKing’s numbers a 17×8 prop will pull 1900 watts. A 17×10 will pull over 2100 watts, 86 amps. This seemed pretty impressive.
When I mounted the motor on my Sbach 342 I used a Xoar 17×8 prop. This prop seemed to give me a great vertical pull. The prop was a little big for the plane and when I landed a little off it struck the tip and which caused the wooden prop to explode. I needed to find a better setup.
I started looking for a better prop setup. A 3-blade prop would probably be best.
I decided to use an APC 15.75×13 3-blade prop. Ideally, a 3-blade 16×10 would make close to the maximum 2100 watts. For an inexpensive solution this was the easiest prop for me to try. As you can see in the above picture it makes the Sbach 342 look pretty menacing!
My NTP Prop Drive motor seemed pretty stout. It’s pretty hefty and definitely has a bit of presence on the plane. As I mentioned earlier, when I put the plane through its maiden flight it pulled pretty well. The one thing I did note and I wasn’t too happy about was a weird noise at and above 80% of throttle. At first I thought it may be the prop. I went to HobbyKing’s page on the motor to see what the wattage numbers were. The stats that I listed above made it seem like I wasn’t pushing the envelope.
The first flight ended with me hitting the wonderful beechwood Xoar prop on the asphalt and destroying it. My immediate reaction was that the prop was too big in diameter. I decided to look into a different diameter prop to see if I could prevent that from being an issue in the future.
I looked around the internet for a 16″ or 15″ 3-blade prop that I thought would fit the plane. I ended up finding the 15.75×13 APC prop shown above. I decided to give it a whirl. The first flight I knew that it had power, but something seemed even more odd with the motor noise at the high end of the throttle. The pull was good and the motor wasn’t very hot when I got it back down. The big inlet on the front of the Sbach probably helps keep the motor pretty cool during flight.
Finally, I got my hands on a 16×10 2-blade. I did a bit of peeking around the internet and it seemed like this would be a good match for the motor. I took five batteries out to the field in order to test it out. On my cheaper Zippy Compact 4000mAh I was able to get around 4 minutes of mixed flight time. This same battery would basically be over in 3 minutes on the 3-blade prop. With my nicer 40c Zippy Compact 4000mAh I was getting close to 5 minutes and the nice Pulse lipo 5000mAh 45C I made it over 5 minutes. I think this is the prop to run!
I may end up going back to the 17×8 in the future. After testing out the differences between the 3-blade and the 16×10 I think this motor does pretty darn well on that 17×8. All three setups have plenty of power. Now I’m trying to figure out which one gives the best vertical performance when compared to the battery drain.
So after I put the first flight with the 17×8 and a couple flights with the 15.75×13 3-blade I noticed that the motor had a grinding noise to it. It sounded almost like it had sand in it. I decided that I better pull it apart to see what was making the noise.
Before taking the outer “can” off the motor I noticed a little piece of metal between the back-plate and the “can”. I poked at it with a pick and noticed that it moved freely. Moving it around seemed to change the sound from a “grinding of sand” to silent. It seemed like this was the culprit. I pulled the motor apart. Warning: This thing has some very, very strong magnets. I suggest having an extra set of hands. Be careful! As you can see above this ring just sat there. It had a “spline” like setup that fit between each of the magnets.
I took some thick CA and glued it down to the magnets. My hope is that it was supposed to be glued in when the motor left the factory. On the next flights it seemed like the noise wasn’t bad. This is leaving me wondering how long this motor will last.
For the price it is hard to beat any offering by HobbyKing. Their prices and shipping tend to make it a fairly easy decision to purchase from one of their US warehouses. Since I started writing this article I’ve put a total of 10 flights on the Sbach. After each flight I’d put my fingers on the outer casing of the motor to see how hot it was. No matter what the prop combination the temperature never was at a point where I couldn’t leave my fingers on it for an indefinite amount of time. Most of the time the motor was cool to the touch.
Early reports from users of this motor had concerns over the magnets coming loose. Do to the noise mine was making I got a chance to inspect the innards. It looks like pretty much every other motor I’ve ordered from HobbyKing. I’ll continue running this one until it give me a reason to doubt it. As for now I think it was a good purchase can recommend it for a replacement for a 60 sized nitro motor.
Head over to Hobby King and check out the NTM Prop Drive 50-60 motor!