Racerstar 8520 8.5x20mm 53500RPM Coreless Motor

ph2t · Jan 7, 2019

Just want to let you all know that the Racerstar 8520 8.5x20mm 53500RPM Coreless Motor is a compatible replacement motor for the tello.

I had a failed motor and replaced it with the racerstar motor, the other three motors remained as originals.

After the replacement was installed the flight test was accurate and tello rock steady whilst hovering.

You can buy a pack of four off eBay for $14AUD. This includes two of clockwise(CW) and two counter clockwise (CCW). Great value and work a treat!

Racerstar motor is at the back of the pic.

Cheers,
ph2t.

bookworm · Jan 7, 2019

Interesting. And does the antenna extension you have fitted help at all ?

shambhu · Jan 7, 2019

ph2t said:
Just want to let you all know that the Racerstar 8520 8.5x20mm 53500RPM Coreless Motor is a compatible replacement motor for the tello.

I had a failed motor and replaced it with the racerstar motor, the other three motors remained as originals.

After the replacement was installed the flight test was accurate and tello rock steady whilst hovering.

You can buy a pack of four off eBay for $14AUD. This includes two of clockwise(CW) and two counter clockwise (CCW). Great value and work a treat!

View attachment 2542

Racerstar motor is at the back of the pic.

Cheers,
ph2t.

it will get hot after few minutes

ph2t · Jan 7, 2019

@shambhu - I have found that it doesn't get hot at all. I've flown two packs through it now and whilst it does get warmer that the stock tello motors, it doesn't overheat. That being said I have now killed a 2nd motor due to a crash into a brick wall in high speed mode so I'll be changing out the other motor later today. Will see how it goes.

@bookworm - I believe it's better than stock from what I've flown at the moment, but not as good as with the wifi repeater. It responds quickly and is better in areas that the stock antenna would have difficulty with. I'm still investigating. I've recently learnt the tello is a dual antenna setup with a patching protocol that switches between which antenna has the better signal. Once I saw that comment made in another thread it does make sense. My walkera F215 racing quad also has dual antennas for the receiver and I believe the concept is the same. currently both antennas are in the same piece of black heat shrink tubing that you see in the pic above, technically they will always have similar signal strength given the lack of diversity (physical separation of the antennas and polarisation (ie: one antenna vertical and the other antenna horizontal). I'm going to work on this more.

cheers,
ph2t.

Mikusan · Jan 8, 2019

****, you have some interesting idea's and mods. Once you got it all figured out, mind making a how-to? Specially the antenna mod. The other topic with the frame and larger battery is also very interesting. Although i wonder if the basic motors can handle the extra weight and if they do, what the outcome of battery duration is.

ph2t · Jan 8, 2019

Thanks mate appreciate the feedback!
I’m working on the antenna mod a bit more, my idea is to have one antenna vertical and maybe the other one horizontal. Vertical antenna mounted on top and horizontal antenna mounted along the bottom of the tello chassis.
Cheers,
ph2t.

ph2t · Jan 9, 2019

OK, all four racerstar motors have been installed and initial tests (VERY initial - no antenna, no case, no camera, just one screw holding the main PCB in place!!) show it to be running really well.

Things left to do:

Run motor wires in place along arms and inside chassis.
Reconnect dual antennas (my own mod - trying out a polarised layout with one vertical and one horizontal).
Reconnect and mount camera.
Assemble chassis covers.

Should be done shortly...

Cheers,
ph2t.

ph2t · Jan 9, 2019

Unfortunately, the rubber feet are really stuck on and I have to use a Stanley knife to cut through.
Some things to note:

The two rear motors house the antennas under the motor, within the plastic holder. It is a small PCB that use an earth and signal area. The little coaxial cable that runs down the rear legs is shielded and only exposes the antenna at the very end. When cutting through the rear motor mounts you will hit this PCB. It gets a bit messy and I see why people cut the original motor cables halfway up the arms and join the motors that way instead. I'll post more on the antenna setup as a learn more in another thread.
The two front motors have nothing in the mount area, cutting through is easy and gets you access to the underside where the cables area.
This is a messy job, I can't use the rubber feet anymore, my tello just lost a bit of standing height. lol..

cheers,

ph2t.

raulvolador · Jan 9, 2019

You are very brave !

It scares me to see the tello open in that way

I'm interested in the antenna mod. Can you post any picture ? Thanks a lot.

raul.

ph2t · Jan 9, 2019

Haha, you may not want to watch this video then

Tello guts I call it.

https://sjcbecatholiceduau-my.share...FMv5oNcNIL7_MBEFVucBGzfvY7RPtmWZmlRQ?e=dkZj2x

shambhu · Jan 9, 2019

ph2t said:
OK, all four racerstar motors have been installed and initial tests (VERY initial - no antenna, no case, no camera, just one screw holding the main PCB in place!!) show it to be running really well.

View attachment 2584

Things left to do:

Run motor wires in place along arms and inside chassis.

Reconnect dual antennas (my own mod - trying out a polarised layout with one vertical and one horizontal).

Reconnect and mount camera.

Assemble chassis covers.

Should be done shortly...

Cheers,
ph2t.

really like your ideas...can you please tell me bare weight of either flight controller or the frame ..i want to reduce the weight to increase flight time... currently i am getting 14 minutes total flight time...how much flight time you are getting...

Ansia · Jan 9, 2019

I crash almost every single time that I fly. I have changed the motors twice now. What I did was cut the wires halfway and just inserted the extra in the little space in the back of the Tello and around the edges, as snug as possible. I suck as precission welding, so will never touch the PCB anytime soon. Good job on your mods. Will look into those motors. Love how they look all in black. Will make the Tello look awesome. Only thing missing is that red top cover that I can't seem to find.

Edit: Just found out they come in red. Screw black!

Ansia · Jan 9, 2019

Just have 2 questions.

How does the motors affect the battery life?
What is the life expectancy of these motors?

ph2t · Jan 9, 2019

@shambhu - sorry mate I don't have any digital scales. I will test flight time on with the racerstar motors and let you know soon.

@Ansia - I can't find any information about the motor's lifetime I'm sorry. As for battery life I would say it is fine. The flight time will give me an idea on how much current they draw. If flight time is considerably shortened then that would indicate a major jump in current drain from the racerstar motors. Without knowing the max discharge rate of the fullymax lipo battery that comes with the tello it is hard to figure out if the motors are taxing the battery or not.

@raulvolador - I have made a new thread about the antenna mod and my reasoning behind it here .

cheers,
ph2t.

ph2t · Jan 9, 2019

OK got some runtime in with these motors. Pretty happy with them as a replacement.
Shot with a gopro on my head, recommend you watch the youtube video in 1080HD-50FPS setting to see the bloody thing!

Cheers,
ph2t.

Ansia · Jan 10, 2019

Can you take off with a fully charged battery and let it hover until autoland and take the time? To determine how much do the motors shorten flight time.

Mikusan · Jan 10, 2019

Do you notice any difference in how it handles outside?

ph2t · Jan 11, 2019

@Mikusan - handles fine outside. Was windy today when I took it for a test run. Had to run in fast mode to battle the wind. The positioning system did its job well.

Runtime so far is good. Flying outside and taking video the whole time to test the feed I found I got 9mins flight time (5.5 minutes normal speed and 3.5 minutes fast speed). I was flying pretty hard and carving it up in the wind.

Cheers,
ph2t.