[BenR]

Hi,

Has anyone here done much in the way of telemetry? I am looking at some stuff online (mostly the EagleTree stuff that I would buy from HobbyKing) but I am wondering if anyone here has any experience that they are able to share.

I am interested in what people measure and what they use it for. I was thinking for me while I am still new that having GPS data and altitude for review would help me with clearing up any gaps I have between what I see when I fly and what is actually happening.

Ben.

[smuzz]

I haven't done any of this myself - but Samste-Steve has, if I remember correctly.

I think most of the time the telemetry data is used to fine-tune power train combinations. However for learning, it would be good fun to be able to replay a complete flight in an animation - and to be able to step in and resume control at any point. Too bad Phoenix doesn't have an API that permits that. I'll be the stuff that Claudio has assembled could be made to do it though!

[kizza42]

My FRSky transmitter module has a realtime RSSI (Received signal strength indication) alert which is very useful to let you know if you are flying out of range (Hard to do) or if you are flying in an RF noisy environment (Like PEMAC). There is also support for other sensors like amp draw, gps etc but I've not played with them yet. I know Jason has either the amp or voltage alert setup on his 3d planes.

Live altitude alerts would be handy to get to know where our flying ceiling is at, but GPS would be too slow and a barometer setup would need to be constantly calibrated to work correctly.

I need to look into an airspeed indicator at some point to put into my jet to make sure I wont overspeed the airframe. The turbine I am looking at has 2.5 times more power than the airframe was designed for!

What you will soon be seeing/hearing is audible feedback for live telemetry, I know of a few projects/companies working on text to speech alerts so you can keep your eyes on the prize at all times!

[Raptorfly]

Hi Ben

I have Telemetry on my DX8 you get to see Batt Voltage, Temp.. RX Voltage and with extra sensors more. Involves soldering and setting extra stuff in the plane.
I also have the Quantum Telemetry. Batt Voltage, Amp draw, Temp.
To be honest, I hardly use them. The most I ever used is listen to the beebs of maybe the Voltage drop on the lipo. Very hard to take your eyes off the plane to look at a tiny display. you will need someone to watch for you which defeats the purpose. I find it useful on my first flight with a new plane and Lipo. I someone (Very rare) ask someone to watch the AMP draw and Voltage and then set up the time for next flight and forget the Telemetry.

[gbanger]

I dont think Telemetry is a "must have" item for anyone apart from the guys that do FPV.
You don't need to know how high you are, that just comes with experience.
Where you are in the sky is as you see it, so all the telemetry on the planet wont improve your flying skill, It will help you refine it, but it is more a want than a need item.
Initial flights with new aircraft are predetermined by doing the maths on the ground with static amp tests and the like. (Remember you aircraft draws more current sitting still than it does moving through the air)
You always do a maiden flight with a new aircraft for a shorter period than you would expect from the battery.
Battery testing after each flight helps you determine exactly how long your flight time should be and then you just adjust your time in the sky on battery conditon at the end of the flight.
Drop by the field and we can explain it to you in detail.
But unless you have a shit load of money and like adding unnecessary weight to your planes, to access information that really dosen't make much difference at all, then I suggest you leave it until you really want it.
Gazz

[Claudius]

I'll be the stuff that Claudio has assembled could be made to do it though!

Yeah, it indeedy does. Dumps out kmz files which you can replay in the Google Earth "flight sim" etc.

I was thinking for me while I am still new that having GPS data and altitude for review would help me with clearing up any gaps I have between what I see when I fly and what is actually happening.

Being not so long in this hobby that I've forgotten what it was like to start learning, I'm comfortable stating that if you're thinking about needing a GPS logger then it just won't be as useful as you think (outside of the cool factor )

What could be useful for a beginner in terms of GPS is post-crash forensics... except you'd want the control surface inputs to be recorded as well, which a simple GPS logger won't give you.

I guess the only things a beginner could immediately gain from telemetry-wise is battery voltage and receiver fades/holds, but there's other techniques you want to learn first before getting a telemetry crutch - I'm in 100% agreement with Gazz's post above on this.

Now, if you'd asked about telemetry outside the context of learning to fly, then the sky's the limit (no pun intended). I've been using the ArduPilot Mega in my UAVs, which can log just about anything you could want - acceleration and gyro data, barometric altitude, dynamic airspeed, signal strength, magnetic heading, gps position (and altitude, and error, and number of satellites, and...), radio inputs, servo outputs, ... and so on.

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Live altitude alerts would be handy to get to know where our flying ceiling is at, but GPS would be too slow and a barometer setup would need to be constantly calibrated to work correctly.

Baro is surprisingly good - better than I expected before using it - even with a cheapie sensor! Normalise the initial readings to 0, and treat the rest as AGL offets. The pressure won't shift too much during a short flight to throw off the values. Some systems will also remove this error by using GPS altitude for long-term, and baro for short term.

What you will soon be seeing/hearing is audible feedback for live telemetry, I know of a few projects/companies working on text to speech alerts so you can keep your eyes on the prize at all times!

Cool! The APM groundstation software does this, and it's surprisingly handy.

The DX-18 can use the data from a Spektrum Air Telemetry module to trigger alarm conditions, and wondered why they hadn't added voice output so you don't have to take your eyes off the screen. (wasn't the Hitech Aurora 9 supposed to do this? Vaguely recall something about this from a podcast)

[secant0give]

You don't need Telemetry to learn to fly RC just as Gazz and Claudio have pointed out.
When your learning to fly you need all the head space you can muster untill things become reflexive and telemetry can unnecesserily add, to an allready heavy work load.

FPV is another matter and the telemetry in my systems is overlayed on the video display handily there is no seperate TX for that as it all comes over the AV link and is recorded on the HDDVR in real time.

Having said that I use telemetry on all my bigger non FPV models. As Kieran mentioned I use the FRsky system and I like it. It's cheap reliable and simple, the alarms I use are all audible, Tho' it can be set up to log all sorts of data on the ground or even plug it in to you lap top, I think there may be a Phone app for it as well.

Why do I use it you might ask ?
1) I monitor RSSI which stands for recieved signal strength Indicator. (this alarm has never gone off) But it's handy to have there and adds confidence basically it monitors the performance of your RC link. Something that must work 100%

2) I monitor the voltage of the powersupply that goes to my RC link and servos. This is a seperate alarm also audible

3) I monitor the voltage of my flight packs, this has a two stage alarm.

The latter is the most usefull. It lets you use a number of different lipo packs with confidence that you won't run out of juice.
Also it enables you to run very close to the money as far as getting the maximum power to weight out of your system.

How you might ask ?

Well when you set up your system with a motor, ESC, prop and battery that is all right on the limit, you can only run it at maximum power for a short burst. You'll see this on motor, battery and esc ratings, something like, so many amps continious and so many amps for 10 seconds. Some very wise people set up their models so that no matter what they wont burn them out by matching there power system components so they can't exceed the continious rating.

However I like to use the burst rating, all of it, why not lets face it it's there to use isn't it, but not for too long other wise the smoke will get out.....right? A 5 second vertical rolling climb at max power looks and sounds great !!...........and it's fun too.

When you draw heaps of current from a lipo pack, enough to put it in that 10 second burst mode, the voltage begins to fall steeply. This doesn't mean that your lipo pack is discharged, just that it's right on the limit and cant give any more. The internal resistance of the pack is limiting the power it can put out and you'll see this in the voltage drop across the battery. As soon as you start drawing less current the voltage rises again and we fly around happily in continious mode.

What I do is monitor the lipo packs voltage and set the telemetry to make an audable alarm when it drops below that voltage threshhold. The FRsky allows two alarm tones one more urgent than the other so there are two voltage threshholds to use for giving the pilot an idea of how the hard system is being pushed and what's left in the pack. I still use a timer for all my flights.