Hi

I'm new to this forum so please excuse me if this question has been up before.

I have in the latest month finalized my Topflight Tutor Kit (an old kit) and returned to C/L after a break of about 15 years. I'm satisfied with the plane as it TOW are less than 900g(31,7oz.) and it tracks nice in the pattern.
But I have a minor headache:  I'm just back from the circle with broken ball-bearings on my second engine, and this after less than total of 15 flights.

The first engine was an cheep Turnigy 3536 from China, I had no expectations of quality to this one, it was a quick start to confirm the concept for me and to check what range of rpm/V I needed.
The second engine are a Hyperion ZS3009, to me known as a quality brand. But my bearings didn't stand 3 flights, a €50 engine should take more than that. I get really unpleasant strange sounds of vibration when I pull into the manoeuvres. And when I a grab the shaft is it an significant play in the bearings.

I always use balances props, i have not pushed the engine with high rpms or power.

Does E-stunt require better ball bearings than a common RC-plane or is it just bad luck?

Hi,
Welcome to our forum. I think you will find lots of help here. We are all still learning ourselves and share our failures and successes and ideas. with each outher Please give more info but like Crist said you shouldn't be going through bearings like that I have close to 100 flights on my atlas motor between a banshee and a Arf cardinal at over 50oz for the Cardinal and I still have the original bearings. On the banshee it was rear mounted on the Cardinal its front mounted for the last 80+ flights. I think that most of us here tend to "oversize" our motors when we use them for CL. In looking up the specs on your Hyperon motor it is "right sized" for an RC plane that weighs the same as yours. The 3014 hyperion series would probably be the minimum that I would use on your plane. The 3020 would be my preferred. Exactly which ones would depend on your battery choice. I know others will chime in. I know Dennis A has experience with the Turnigy's. to make things easier for the others here is the link for the hyperion motor specs http://www.hyperion-world.com/products/product/HP-ZS3009-20. Good luck


 

Hi folks

Thanks for your input. I will try to answer your questions about the plane and setup to make the picture clear.

The plane is a TopFlight Tutor which is a 45" plane, it is smaller than a regular .35-.40 plane and slightly bigger than a .25. My Aim for this was just to getting started and try out different combinations of motors, props and batteries. I also like to build as light as possible which explain my choices of motors.



The motors have been front mounted as this makes it easier to change motor without significant changes in position and C.G.


I have so far been doing some testing with different props  (9x4,5, 10x5, 11x5,5, 11x7 and 12x6) and it seams that a combination of pitch and rpm which gives a pitchspeed in the rage of 75-80km/h are good with my 17,5m lines (might be to long?)
Batteries are all 3s Lipol with 2000-2500mAh, they hold about 10-10,5V at a 25A load.
I have initially used an regular reciver with a transmitter on the ground, but the last weeks have a Will Hubin Timer which makes things easier.
The motors I have tested are:
- Turnigy C3536-1300rpm/V: I have run Turnigy for some years in RC and have never before had problem like this.
- Hyperion ZS 3003-1100 rpm/V, this motor are actually a little to low in the rpm/V number. I had to use high pitch props like the 11x7 to get this moving in the right speed.
The rpm has been in the range of 7500-9000 rpm and input power of 250W-280W, again 270W looks like a good number for this plane.

I can not see any problem to run out-runners at the weight of 100-125g with these numbers, I have RC-planes where I stress the motors significant more.
I guess I have to call out for warranty of the Hyperion (one week old) and figure out what to do next. I do have an Turnigy SK 3536-1450rpm/V with bigger bearings, this motor are in the high range of rpm/V, but a 12x4 might be a good choice? 12" are bigger than this plane was designed for, are there an upper limit of diameter or are bigger = better as in RC?

If I get things right are the next step to build a Brodak Vector .40 to build for next year.

Per,

Congrats on trying out EP CL stunt.  You are on the right track with your motor selection.  I have several Turnigy motors and haven't had the bearing trouble your having.  The SK series motors are significantly better than the standard gold series.  The gold series use a soft shaft that is a bit on the small side for the bearings.  The bearings themselves too aren't very good, but they hold up to normal use.  The SK series are solid and very well built motors.  I have a 35-42-1000 & 35-48-1100 SK and they both were used in a EP Q-500 @ over 13,000 rpm and have about 30-40 flights a piece on them.  They were both run at a constant 600-650 watts for 2.5 minutes at a time and both still look like new.  I have some turnigy in-runners that I have in a EDF running at over 50,000 rpm and after 200 flights, the bearings are shot.  But that is a bunch of time at that kind of running.

The 35-36-1450 SK with 3S 3000's and a 10 x 5 APC would be a great set-up for the Tutor.  Current may be high with the 12 x 4 prop, but as long as you are within the limits of the system before takeoff, give it a shot.

For the 10 x 5, I would launch @ around 10,400 to 10,600 rpm.  Shoot for a static current of 33-35 amps.  What type of controler are you using?  Does it have governing or heli mode?  This is very handy in EP CL stunt as it helps to balance the power in the flight and control speed in maneuvers.

As far as mounting, please read through the Resolve 570 thread that Crist Rigotti did.  His profile mount for his Scorpion motor is ideal for how out-runners need to be mounted to balance the bearing load.  Speaking of which, do you know which bearing failed?  I have flown stunters mounted the same as you and haven't had the same problems.

I look forward to hearing about your flights.

Archie Adamisin
Muncie, Indiana 

I think Alan hit the nail on the head. Your motor shaft is too long. You should shorten the shaft and mount the collet so it just clears the front of the motor.

When you cut the shaft take a piece of towelling and pierce the motor shaft through the center of the paper or cloth. Wrap the rest of the motor in the towel and then cut and deburr the shaft. Vacuuming any dust off the towel then unwrap it.

Better motors are better balanced, have better bearings and harder motor shafts.

Kim.