Telemetry

[EAS]

I expect the only way to get any telemetry, is to have a Transmitter that has that capability? Is that right? I've seen nothing in my Futaba 6J that indicates it can.

I'm most interested in motor RPMs, compared to throttle position. Even if it's a "bench" only hardwired setup.

Anybody know of one?
Thanks.

 

[LitterBug]

Have not played with modern Futaba gear and Can't speak to that brand. In general, both the transmitter and reciever must have telemetry. I see nothing in the 6J manual to indicate it supports telemetry. The Sbus / S.Port protocols Futaba uses are what most of the "open" radios are built on. If you have s.port on your RX, it should be telemetry capable.

I Have a handful of Spektrum BNFs that have Basic Battery and RSSI telemetry. Spektrum has been very late to the telemetry game and are just now adding telemetry protocols/ports that FCs may incorporate in the future.

The majority of my "Open" radio birds with flight controllers have full s.port telemetry. Planes, drones, ground vehicles, etc.

 

[Merv]

.... Even if it's a "bench" only hardwired setup...

Would a hand held tachometer work? Like this one.

https://www.amazon.com/dp/B004Q8L894/?tag=lstir-20

 

[LitterBug]

Would a hand held tachometer work? Like this one.

https://www.amazon.com/dp/B004Q8L894/?tag=lstir-20

Similar to that, there are phone tachometer apps that use the microphone to show RPM.

 

[EAS]

Would a hand held tachometer work? Like this one.

https://www.amazon.com/dp/B004Q8L894/?tag=lstir-20

I wouldn't be willing to put a reflective mark on my motors....

 

[LitterBug]

I wouldn't be willing to put a reflective mark on my motors....

Many don't need it. they bounce IR off the prop.

 

[EAS]

Many don't need it. they bounce IR off the prop.

That's what it says in the details of the page...done using a reflective mark (included). I was really thinking something hard wired, but I appreciate the suggestion.

 

[EAS]

Have not played with modern Futaba gear and Can't speak to that brand. In general, both the transmitter and reciever must have telemetry. I see nothing in the 6J manual to indicate it supports telemetry. The Sbus / S.Port protocols Futaba uses are what most of the "open" radios are built on. If you have s.port on your RX, it should be telemetry capable.

I Have a handful of Spektrum PNPs that have Basic Battery and RSSI telemetry. Spektrum has been very late to the telemetry game and are just now adding telemetry protocols/ports that FCs may incorporate in the future.

The majority of my "Open" radio birds with flight controllers have full s.port telemetry. Planes, drones, ground vehicles, etc.

I think my 6J may have an S-Port function, but I need to verify that.

 

[LitterBug]

That's what it says in the details of the page...done using a reflective mark (included). I was really thinking something hard wired, but I appreciate the suggestion.

Hardwired to what? Is this a gas, glow, or brushless motor?

 

[EAS]

Hardwired to what? Is this a gas, glow, or brushless motor?

In between the battery and esc....or even between the ESC and motor.

 

[EAS]

A bit like an automotive timing light. Connected to positive and negative ...and then a sensor on one of the motor wires.

 

[Merv]

I wouldn't be willing to put a reflective mark on my motors....

What about this one. I believe it’s old school, purely optical. Don’t use it in artificial light, the flickering of ac lights will mess up the reading. Use it outside in natural light. The upside, hold it up to a light bulb, if it gives the right answer for the Hz in your country, it calibrated correctly.

https://www.horizonhobby.com/produc...7-TNNxcxTGphLbntjL3MHaxoSE9nxeDBoCQukQAvD_BwE

 

[LitterBug]

In between the battery and esc....or even between the ESC and motor.

Futaba has the SBS-01RB (ESC) sensor that would connect to two of the three motor wires at one end, and the S.Bus2 port of the RX to send the data back to the TX. See manual here: https://futabausa.com/wp-content/uploads/2018/09/SBS-01RB.pdf

Again, your RX and TX both must support telemetry for this to work.

 

[Tench745]

I'm pretty sure most telemetry tachometers use some kind of magnetic pickup that senses the magnets in the brushless motor bell, or an optical sensor. The problem with anything using motor pulses or magnets, you'll have to figure out just how many pulses or magnets there are per revolution.
A hand-held tach seems like a much easier solution to me. And there are some that can read without using reflective tape.

 

[LitterBug]

I'm pretty sure most telemetry tachometers use some kind of magnetic pickup that senses the magnets in the brushless motor bell, or an optical sensor. The problem with anything using motor pulses or magnets, you'll have to figure out just how many pulses or magnets there are per revolution.
A hand-held tach seems like a much easier solution to me. And there are some that can read without using reflective tape.

You are correct. The Flight controllers that read the ESC telemetry directly have to know how many poles per revolution just like the Futaba SBS-01RB has to know how many poles.
Audio, optical, and magnetic tachometers likewise must know how many pulses to expect per revolution. Optical sensors bouncing off props need to know how many blades are on the prop.

@EAS , What is the purpose that you are trying to determine RPM for? Curiosity, debugging a problem, testing max RPM with different props?

 

[EAS]

You are correct. The Flight controllers that read the ESC telemetry directly have to know how many poles per revolution just like the Futaba SBS-01RB has to know how many poles.
Audio, optical, and magnetic tachometers likewise must know how many pulses to expect per revolution. Optical sensors bouncing off props need to know how many blades are on the prop.

@EAS , What is the purpose that you are trying to determine RPM for? Curiosity, debugging a problem, testing max RPM with different props?

JP Hobby 70mn EDFs... curiosity I guess, but I also would like to know how well they compare to the manufacturer's specs....and a coulpe other interests just for my testing info.

I'll also look at the other links above.

 

[EAS]

Futaba has the SBS-01RB (ESC) sensor that would connect to two of the three motor wires at one end, and the S.Bus2 port of the RX to send the data back to the TX. See manual here: https://futabausa.com/wp-content/uploads/2018/09/SBS-01RB.pdf

Again, your RX and TX both must support telemetry for this to work.

I don't think my RX supports it, but I'll try and find it's specs.

 

[EAS]

.....there are some that can read without using reflective tape.

I might be interested in something like this, but I know the accuracy of many of these isn't to good. I don't want a permanent install, just bench testing. JP Hobby says these EDFs are tested to 80,000 rpms and recommend not to go over 76k. I expect they're testing with a quality DC power supply...so I'm not expecting 76k, but I'd like to know how high they're going.

 

[EAS]

What about this one. I believe it’s old school, purely optical. Don’t use it in artificial light, the flickering of ac lights will mess up the reading. Use it outside in natural light. The upside, hold it up to a light bulb, if it gives the right answer for the Hz in your country, it calibrated correctly.

https://www.horizonhobby.com/produc...7-TNNxcxTGphLbntjL3MHaxoSE9nxeDBoCQukQAvD_BwE

This one at $35 might be worth trying.

Updated; it only works with 2, 3 or 4 blade propellers. Oh, well.

 

[LitterBug]

might have a look at this
https://fanjetsusa.com/product/gt-power-tachometer/
Generally speaking, static thrust and RPM on a stand will be lower than can be expected in flight.