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Horizon Hobby Sport Cub S Motor oscillating\pulsating

Hi - I have a Sport Cub S, just purchased. Actually received one from Horizon Hobby last week, but the elevator would not respond and the motor pulsated badly.

They agreed to take it back. But I couldn't wait so I purchased another one yesterday. After about 3-4 minutes in flight, the motor began pulsating and the unit of course lost altitude and landed.

Not big crash, flying only on thick grass.

I tried a fresh battery, (1S3.7v 150mA 25C)also new, but the pulsating continued so I left the field.

After I came home, I tried it again and the motor did not pulsate. You think this is simply the motor getting hot?

I'm kinda new to planes, been into helicopter for the past few years. Also have a HH Champ which flies fine with no problems.

I'm hoping I didn't get another "lemon" unit. This plane has great reviews so just wonder if I'm doing something wrong.

I fly in the beginner mode but when the pulsating occurred, I tried it in all flight modes with the same result.

Appreciate any thoughts you may have.

Thank you.

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Battery issue?
by: David V.

A "pulsating" motor is usually a sign of a nearly depleted battery. Are you confident it is fully charges? Can you measure its voltage? (Ideally above 4V before starting flight.)

Depleted battery
by: Anonymous

Flight time on that battery is around 4 minutes give or take.

Motor Cutting Out
by: George

My Sport Cub S is doing this too. After third flight day.

All flight batteries charged prior to taking the plane to the park.

I notice it most as the plane is flying away from me after hand launching it. At roughly 60' on the up wind run the motor seems to just stop. I fly only on calm days so my throttle is at about 70%. Bringing the plane around and closer to the controller seems to eliminate the cutting out issue.

Not a long term solution in my book. I think I'll call Hobby Zone on Monday and see what they have to say...they have been very helpful to me through the ordering and delivery process.


Motor pulsating
by: Ross

This is the second Cub S that I have owned, just received it yesterday and took it out for its first flight. Batteries were fully charged. At just about full throttle the motor starts pulsing then cuts off completely. I tried multiple batteries thinking maybe it was a low voltage problem but the issue continued. I haven’t tried the transmitter from the first cub I purchased last year thinking it could be a faulty remote control. I really like the plane and it’s flying capabilities but like I said, this is the first time I have never seen this issue and I can’t seem to find anything in the manual about it. Looking online, I see there are a lot of people with the same issue

Motor pulsing (continued)
by: Ross

After my comment yesterday I decided to not give up and pull the plane out again today to see if this problem can be fixed. I have about eight batteries for the cub sport because I love to fly up and want to spend as much time on the field as possible.

However, I noticed a couple batteries don’t connect to the plane immediately and when it does finally connect It’s not fully secured to the power wire. Once I adjusted the two prongs on the inside of the wire where you connect the battery, it’s seemed to fit perfectly and the pulsing issue stopped. Another thing to look for is the connector piece of the battery it’s self.

If you hold it upright and look at it from the side you may see the little white piece bent to an angle which also will make it hard or difficult to connect to the planes wire. Sometimes you may have to jiggle the battery just right to get it to connect properly.

Another tip that may help is if you have the manual for the plane which is located underneath the Styrofoam in the box, on page 17 of troubleshooting it does state a problem of a pulsing motor which in case the it states the battery power is down to the point of receiver ESC and a low-voltage cut off. This again would have to do with the battery.

These batteries are not the best for flying but they do get the job done if you have a proper one. Like I said, I have eight batteries and two of them did not work because it was not connecting properly to the wire.

I believe the plane is letting the flyer know that the battery is not completely secure and is at risk of coming loose during flight.
I hope this helps.

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