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Aug 22, 2019, 03:48 PM
Team Hello Kitty
SoaringDude's Avatar
Thread OP
Discussion

Flying F5J without telemetry?


Fairly often I find myself talking with guys who are using older non-telemetry transmitters for F5J. Many of them ask how to set up a mini backup battery system which works best if implemented using voltage telemetry and voice alarms. Full telemetry gives you many other useful alerts and alarms. Having converted from Airtronics to FrSky Taranis two years ago I know how daunting the task of switching to a new TX system can seem. The good news is cost is NOT an issue.

FrSky recently announced a new series of next-gen transmitters. Same low prices but with faster main boards, more memory, new features, etc. Vendors are just starting to sell them. Aloft just listed the new Taranis Plus ACCESS. This is a FULL telemetry TX system with tons of capability and built-in OpenTX software. Cost is $190 for the TX + $15 for a Lipo TX battery. There are also higher end TX units for more $. e.g. the Taranis Plus Special Edition 2019 will go for ~$250 when available (early Sept). There are many FrSky RXs and sensors available and they are also low cost. I use the G-RX8 with a built-in altimeter that comes in very handy for F5J practice. They cost $40.

Maybe this thread can be used to help answer questions for guys that are considering switching to a telemetry system. Now's a great time to consider doing it.

Cheers,
Chris
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Aug 22, 2019, 06:53 PM
Registered User
How much greater is the current draw with those telemetry systems?

Seems to me that battery problems are quite rare if you take care of them.

Yes, I'm a Luddite.
Aug 22, 2019, 09:16 PM
Sagitta Fanboy
Quote:
Originally Posted by lincoln
How much greater is the current draw with those telemetry systems?

Seems to me that battery problems are quite rare if you take care of them.

Yes, I'm a Luddite.
No significant difference on the latest receivers, you're looking at 50-100mA draw from the receiver at most. The receiver draw is only really an issue on DLG's where the RX packs are tiny and servos are too.
Aug 23, 2019, 12:54 AM
Registered User
Tuomo's Avatar
I do not understand the question as telemetry is simply not needed in F5J. Actually use of telemetry is very limited in rules.

The alerts just add confusion to flying. It is best to turn them off. I say this with 10 years of Jeti 2.4 experience. In the beginning Jeti used to give weak signal beeps very often. The warnings just annoyed me at the moment when flying was critical.
Aug 23, 2019, 01:12 AM
Team Hello Kitty
SoaringDude's Avatar
Thread OP
Tuomo, I have exactly the opposite experience with FrSky: for me telemetry has become an indispensable set of tools. Not at all confusing given the FrSky/OpenTX flexibility of how I can configure and receive the telemetry alerts. Maybe a demo of some of this would help others...
Aug 23, 2019, 01:57 AM
Registered User
Sensoar's Avatar
Knowing in real time the voltage of the battery cell > priceless
Aug 23, 2019, 02:57 AM
Registered User
Aaro's Avatar
Hi,
If talking about "F5J-flying" instead of Sunday flying there is really no need for battery voltage telemetry - just change a new battery between 1-3 flights depending on setup and launch intensity. I find any extra wires or components more complicated than creating any real safety or reliability. Keep it as simple as possible, and avoid also systems/setups that require changes when flying in FAI-regulated competition.
Aaro

Quote:
Originally Posted by Sensoar
Knowing in real time the voltage of the battery cell > priceless
Last edited by Aaro; Aug 23, 2019 at 03:39 AM.
Aug 23, 2019, 05:57 AM
Registered User
I think you are more concerned with telemetry (usually for motor batery) and you should be concerned by a reliable power source for the servos . In F5J yoiu sue the motor 10-20-30 seconds ...byt you need to have reliable servos 10-15 minutes.
Not to mention the fact that new 2019 FrSky models have a new radio module ISRM (with variants between models: ISRM-S-X10, ISRM-S-X9, ISRM-P, ISRM-N) but there is no FCC certification for them:
https://fcc.io/XYF
The last certification is for FrSky X-lite last year in May.
In your place before making plans to switch to a new radio system I'd check first if this radio is FCC certified in the first place.
Aug 23, 2019, 07:51 AM
Registered User
Tuomo's Avatar
Quote:
Originally Posted by SoaringDude
Tuomo, I have exactly the opposite experience with FrSky: for me telemetry has become an indispensable set of tools. Not at all confusing given the FrSky/OpenTX flexibility of how I can configure and receive the telemetry alerts. Maybe a demo of some of this would help others...
My experience was general, nothing FrSky-specific. The warnings work about the same in all radio systems.

One question about practical decisions about F5J flying. You are flying a competition flight and hear beeb beeb beeb warning: left wing tip is about to explode Just 2 minutes to go, would you try to land? Or continue your flight hoping that everything will be ok? I am 99% sure that you (like everybody) will continue the flight.

I take this example because in the early days of Jeti 2.4 we got low signal warnings very frequently . I was flying F3J then. In the end most competitiors just turned the warnings off (or reduced their sensitivity). Technically signal warnings are based on telemetry link quality, from rx to tx. That signal is much weaker than the actual control link from tx to rx.

From the point of competition flying warnings are theoretically nice features that actually have very little functionality for the point of view of practice.

However, I find telemetry logging sometimes quite useful when analyzing aftermath of a crash. A moth ago I crashed Xplorer from low altitude when searching for a thermal during 30 sec launch window. Initially I just thought that I made some kind of pilot mistake as the weather was windy and very turbulent. However, when checking Altis and ESC loggings I noticed that there was a sudden in flight black out. Mysteriously altitude logging ended at 10m altitude... This lead me to check batteries where the actual problem was.
Aug 23, 2019, 08:08 AM
Barney Fife, Vigilante
tom43004's Avatar
I have landed competition flights early on more than one occasion when I received a telemetry warning from my transmitter. Safety first. This is after all just a hobby.

Guys who risk safety to max a flight are frankly annoying to me. Yes, in a WC environment you may take more risk than Sunday flying, but that accounts for a very small percentage of the flying population, and an even more microscopic percentage of flights.

Use every tool available to learn about your setup, make adjustments, and be safe when you practice. Why use a different setup for competitions when the safety functions of telemetry are legal?
Aug 23, 2019, 09:31 AM
Registered User
Tuomo's Avatar
Quote:
Originally Posted by tom43004
Use every tool available to learn about your setup, make adjustments, and be safe when you practice. Why use a different setup for competitions when the safety functions of telemetry are legal?
We never change settings. Not even for fun flying

I still argue that most telemetry warnings are more like a gimmick. First, they increase complexity, which is always a risk as Aaro mentioned. Second, they are often useless. When that low signal warning kicks in for a reason, pilot anyway notices the situation because of control difficulties. Thirdly, what does the low battery warning help when you are in 300m altitude - 99% sure that the plane will crash anyway.

In competition environment most of the risks come anyway from aspects of the task. For an example, midairs, loosing eye sight of plane or landing out to trees are much more real possibility than equipment failing.

Personally I go to extremes with safety. I check battery before each flight, improve my radio installation if needed, replace suspicious servos etc. No telemetry can replace these preparations
Aug 23, 2019, 10:00 AM
Barney Fife, Vigilante
tom43004's Avatar
Agreed... most of what you list in competition are unavoidable risks.

On telemetry, twice now with DLGs I have found bad servos and replaced them before they showed symptoms because of telemetry showing me much higher than normal current draw or battery consumption. Bench testing later proved the failure. One other time I found a faulty receiver (antenna had a broken solder pad) because the warnings popped on my TX shortly after launch. I didn't know at the time what was wrong, but I knew that airplane didn't squawk about RSSI but on that particular day it did. I switched to a backup and flew, then found the problem when I returned home.

Being a full scale pilot also maybe makes me a little overly cautious. I have lost a couple of friends in "real" sailplanes because of avoidable situations.
Aug 23, 2019, 11:01 AM
Still circling in sink...
Quote:
Technically signal warnings are based on telemetry link quality, from rx to tx. That signal is much weaker than the actual control link from tx to rx.
Tuomo, are you sure this is true? If so, then why, when you do a range check and set the Tx to low power, do you get a reduction in RSSI?

It seems to me that RSSI is only useful if it is the signal strength from the Tx, as received by the Rx. That value is then transmitted back to the Tx by the telemetry function.
Aug 23, 2019, 11:19 AM
Team Hello Kitty
SoaringDude's Avatar
Thread OP
Tom you are correct, RSSI as seen at the TX is the actual received signal strength that the receiver sees. That RSSI value is sent back in a data packet on the telemetry link.
Aug 23, 2019, 12:52 PM
Barney Fife, Vigilante
tom43004's Avatar
RSSI = Received Signal Strength Indicator


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