richg99

In August I acquired a Parkzone T-28 with the included motor. The motor seems to be similar to a Parkzone 450. It has run just fine so far.

Now, the motor runs up to about half speed and then flattens out. It actually drops off a little bit in RPMs after I go past half way on the throttle setting.
1. I reset my DX6i (thinking that I might have messed up the setting somehow) No luck. No change.
2. I replaced the battery with another fully charged one. No luck..No change. ... 3c 2100 mah Lipo
3. I called Horizon and the guy who I spoke to opined that it might be the ESC, but he was in sales, not service...so I have to call back on Monday.
4. A knowledgeable friend at my club said it might be the ESC.
5. I happened to have a 40 amp brand-new ESC here, so I swapped it out..No luck. No change.

Might it be the motor?? No major crashes, but certainly the prop has been stopped by the ground while taxiing a few times. Our field is very rough and even with larger three inch wheels, a plane can easily get caught up.

Your ideas and opinions are appreciated. thanks Rich

toywizard

It almost sounds like partial bearing seizure once you hit a rpm the bearings dont like.

Anyone else have bearings doing a partial seize? I have had that happen during flights and then it comes out of it.
I end up changing the bearings and all is fine again.

I did have a brand new motor have the bearings fail right off before too.

Matt Kirsch

My Feedback: (21)

Given your troubleshooting, the motor would be the next, and only, logical conclusion at this point.

richg99

thanks, Matt... However, it just puzzles me that the "drop off level" is so consistent. Are there "high-speed" windings and "low speed" windings? If there are, and the "high speed windings" were shorted etc. then it would make sense to me. I know nothing about the windings on a motor. thanks Rich

richg99

Some further data. A friend, who is traveling and can't help directly on this...asked me to advise what amp-draw I am getting as I go through the throttle acceleration of the motor.

This Park 450 style motor is drawing only 2.5 amps at half throttle, and then, as it appears to be slightly slowing down in rpms......draws 3.4 amps at the high end. The motor is obviously not running very fast at all. Does this sound like the symptoms of a partially burned out motor?

If it is the motor, would a 28 36-10 motor ( 79 gram; 1100 kv with 52 oz thrust @ 10x5 prop or 46 ox with 9x 3.8 prop) do the job? I see such a motor is available at Lazertoyz.com for $24.00. I've bought a number of other motors there in the past.
thanks, Rich

Dr Kiwi

If that is the brushless 450 motor, it should be drawing 12A-15A - clearly something is wrong if you are drawing <4A at WOT. [What brand of ESC are you using?]

The 2836 you mention should be more than enough!

richg99

The "new" 40 amp ESC is a no-name brand that I ordered when I was getting some other stuff. I bought two of them and the other one works fine..so I presume that this one works fine, too.

The motor's reaction is exactly the same as its reaction when attached to the 25 amp ( I think that it is a 25 amp..there are no markings that I can see readily) ESC that came with the kit. After talking to Horizon tomorrow, I'll probably just put the original ESC back, unless I have to buy another brand motor. Then the 40 amp will probably stay in.

As far as the amp-draw of the 450 Park. No one seems to actually know EXACTLY what motor Horizon put into this kit. It's suggested replacement is the 450 Park, but that motor is physically different in size according to a picture someone posted when substituting the 450 park..... one has to extend the motor much further forward by beefing up the motor mount area.

Thanks for all of the help, as always... Rich

Matt Kirsch

My Feedback: (21)

Sounds like a burned winding to me. Kinda like a V8 engine only firing on 5 cylinders...

According to Horizon's website, the Kv rating on the motor is 980 RPM/Volt. What you'll be looking for as a replacement is a motor similar in physical size and Kv rating to this existing motor. Horizon should replace it for you under warranty, though.

The 2836-10 from Lazertoyz has an 1100 Kv rating, which means that it will spin a prop at a higher RPM on a given voltage. You'll probably want to reduce the size of the prop to the recommended 9x3.8, or maybe a 9x4.7, to keep from overloading the motor. The stock 9.5x7.5 will definitely be too much for the motor.

richg99

I spoke to Horizon today and they are sending me a new motor. We will see how that works out. thanks, Rich