Onboard Recording / Telemetry Device - Suggestions? - RC Groups
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Apr 04, 2005, 10:26 AM
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LoopZilla's Avatar

Onboard Recording / Telemetry Device - Suggestions?

I am in the market for some onboard data recording devices, possibly with optional telemetry.

My goals are to achieve battery voltage, current, Ah, watth, temperature (3 sensors would be optimal), and optical RPM (magnets are a pain).

The only system I can seem to find is the following:

Eagle Tree Systems Flight Data Recorder
Eagle Tree Systems SeaGull Telemetry

Can anyone offer any experience with this device or others?
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Apr 04, 2005, 10:45 AM
FPV Enthusiast
martinic's Avatar
Found this one too: RCATS R/C Telemety Systems. Seems to be more expensive than the Seagull unit though.
Apr 04, 2005, 10:56 AM
FPV Enthusiast
martinic's Avatar
The reviews of the Seagull unit (including one from RC Groups) are quite informative. Looks great.
Apr 04, 2005, 01:20 PM
Registered User
Here's another
Got one already built - works great.
Data has to be entered into excel though to analyse.
Apr 04, 2005, 02:06 PM
dgoss's Avatar


What class machine are you thinking of putting this on? I have a T-Rex and the datalogger was the one that seemed to be light enough but I wasn't sure about it being so homebrew. Maybe the Eagletree one if it was uncased is not that large. I didn't see a weight for the RCATS but it seems that with the datalogger being a second unit it is too heavy for my needs.

I'm curious, do you have a weight target (yeah, .1g )?

Apr 04, 2005, 02:16 PM
Day by day...
LoopZilla's Avatar
Good question, but one I am open to. I am mainly going to be using the unit to test a heli platform carrying sensors and such, so I would most likely need to ADD weight to get meaningful data (simulating the sensor and equipment weights).

However, I would like to be able to use the unit to optimize my T-Rex and other helicopters, so light is nice too.

I believe the Eagle Tree is 1.5oz (42 grams), so something equivalent or less is optimal. I really wonder what it would weigh without the case and less sensors.

I agree with the datalogger idea, but I just don't have the time to build from a schematic or kit. I need a solution yesterday, and bench testing is just no fun...
Apr 04, 2005, 02:34 PM
dgoss's Avatar
I'm interested in this, I'm glad to see your thread. My feelings too, I wasn't quite sure I was up to the datalogger level of experimenting right now. For someone who needs a custom system it seems like a good base - if they're willing to do the work. I have a feeling the Eagle Tree is a good middle ground, esp if de-cased for the Rex.

Please keep us updated on your project, sounds interesting.

Apr 04, 2005, 05:11 PM
Day by day...
LoopZilla's Avatar
I just spoke to Bill Parry at Eagle Tree Systems about my needs, and I ended up purchasing a Flight Recorder v2. All of his answers were where I needed them to be, or better, and the conversation was very enlightening.

What I do know now is that without the case, the unit with sensors is in the 23 gram range (+/- 5 grams depending on the sensors used). I wouldn't take that weight to the bank, because this was relayed information over the phone, but I imagine it will be really close.

I also found out you can run a 3rd temperature probe if you modify the exhaust temperature sensor. That way we could actually measure motor, battery, and ESC temperatures simultaneously. I will also be able to collect voltages and current. Add RPM to that, and this system will collect everything I need.

For now, I only purchased the Flight Recorder, but plan to add the Seagull Telemetry expansion kit later. Even with the Tx addition to Flight Recorder, the unit will still come in well below 50 grams total weight.

It should arrive Wednesday, so more on the unit then.

Still, if anyone has any other products in mind, please post.
Apr 04, 2005, 05:27 PM
dgoss's Avatar
Nice. Can I ask what you're testing?

Apr 04, 2005, 06:21 PM
Day by day...
LoopZilla's Avatar
Mainly the 'idea of a T-Rex' as a camera platform. It is becoming so highly modified, I'm not sure what to call it at this point. I have a thread in the works about the RotorWorkz CCPM frame I am using as the foundation airframe.

However, there are so many factors that are different than normal, and different vendor's products I am using. So, I am thinking about starting a new build thread more in line with my real topic - an ultra smooth, stable, extremely easy to fly micro heli sensor platform capable of lifting quite a bit of weight. What would you call that?
Apr 04, 2005, 06:36 PM
dgoss's Avatar
Great project. I'd love to hear more as you go along. I find some of the simple thread titles seem to go well, I always over-name them! Maybe just "Rex lifting platform" - but you've done something catchy with "Blingless functionality!" Love that!

I'm curious to see what you can lift, I've been interested in doing some tests but the key is to do what you are and quantify things a bit.

The Robbe Eolo is interesting as sort of a next-size-up heli too if you find yourself at the Rex's limits. But I bet you can do something interesting in this class.

Are you interested in adding some type of auto piloting or sensor assisted flight (I'm picking up on the "extremely easy to fly")? I'm not sure the Rex would be able to hand the equipment but there are some interesting threads over at RR in the AUV forum.

This is all pretty cool stuff - my actual paying gig is that I do aerial photography for films and commericals, all from the full size helis (mostly the Eurocopter/Aerospatiale A-Star AS350 & Twin Star AS355). We use pretty large gyro-stabilized computerized motion picture cameras that are in 36 inch pods and weigh 200lbs for the pod - closer to 550lbs for the whole rig with mounting bracketry and counterweights.


Like this:
Apr 07, 2005, 11:27 PM
Day by day...
LoopZilla's Avatar
I received the Eagle Tree Flight Recorder yesterday, and am already making the plans to purchase the telemetry unit. I haven't even hooked it up yet, but my brain is going into high gear after just reading the manual! The manual was VERY well written for such a technical document, and after reading it on the couch, I feel like I have NO questions about it's operation. So many ideas!

I didn't know altitude and airspeed were included sensors! The Pitot tube will be slightly challenging to get good readings, but I assume I could mount it underneath the canopy to get it out of main rotor wash somewhat.

I also didn't plan on using the servo recording features, but since I found out it detects glitches, I will give it a shot.

This thing is much smaller than I expected, but I haven't pulled it from the case yet. I'll weigh before and after with all the sensors (before and after trimming them as well).

OK, so on the T-Rex, I plan to monitor:

Main motor temperature
ESC temp
Battery temp
Servo motion and glitching
Battery Current
Battery Voltage
BEC voltage

I hope to get it into the air tomorrow and will post screen shots of the data. I'll also do some simultaneous video, and see if I can overlay the software screen onto the video. Then we can see the data with the visual of where the controls are and what the heli is doing.
Apr 07, 2005, 11:36 PM
dgoss's Avatar
LoopZilla - I'm jealous! Sounds great! I've got to go check out the site again - I don't remember thinking the unit was so well suited for this application but it seems perfect. I'm looking forward to more posts. Please take a few pics of the build or at least of the unit installed and with the sensors in place.

Thanks for the very complete update!

Apr 07, 2005, 11:47 PM
Day by day...
LoopZilla's Avatar
I was complete shocked when looking over the unit. Their website does not do it justice, and the reviews online aren't very informative. I'm not often pleasantly surprised, but this package was MUCH better than I had expected it to be.

Will keep posting...
Apr 08, 2005, 01:05 AM
Registered User
ScotY's Avatar
I've been using the Eagle Tree FDR for some time now...works perfectly. I recently picked up the Seagull downlink but haven't yet had time to try it out. I really haven't felt the need, but was really curious what kind of data I could get out of the T-Rex. My biggest concern was lack of space...I'm not sure how much, if at all, the Seagull transmitter will affect the radio gear and there's not much room to move things around.

Please keep us posted on how that works out.

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