Telemetry reset when using an external taxi tank?
 

I know this question has been asked before, but I cannot find the thread with all the good information.

I need to use a start-up/taxi tank in order to save some fuel from my onboard supply, to have a longer flight. So I will appreciate any suggestions of how I can reset the telemetry (on my 18MZ) after I disconnect the external tank, but before take-off. Or how can I start the telemetry just before I take off?

Cheers,

JanR

Link the timer to the gear up switch.

I was actually asking about a telemetry reset.

Regards,

JanR

What type of sensor are you using? One solution is to use a normally on physical switch to interrupt the sensor. On my Jeti I can set the trigger voltage higher than idle so it will reset only after advancing the throttle.

Mark,

When you say; use a normally ON switch. Do I understand you correctly that you put a switch inbetween the telemetry unit and the Rx (or between the ECU and the telemetry unit - that is normally on) and to switch the signal/power? Then, when switching one of these ways, does that reset/start/switch off the telemetry?

Thanks,

JanR

Hi JanR

With the xicoy telemetry units I use a Turnigy receiver controlled switch where I use the two red leads (switch) between the input side of the telemetry unit on the red ( middle cable). I then control the reset using the sprung trainer switch on my transmitter.
https://cimg2.ibsrv.net/gimg/www.rcu...8b8c9fa54b.png

Neil,

Thanks for that. So you put the switch between the ECU and the telemetry adapter on the positive lead. The sprung switch on your TX is always ON, so when you switch, it switches OFF and when you let go, the spring switches the TX switch back ON. Right?

JanR

That's correct. You can test which side of the sensor to mount the switch by simply unplugging the ECU side or the Rx side. If you are short on channels you can mount a little push button switch on the side of the fuse to accomplish the same thing. Most push button switches can be wired to be normally on or normally off.

How close are you to running out of fuel when you land? Are you running that close to dry that you have to know exactly how much fuel you're using while on the taxi tank? I understand you can be held on the taxiway for a while, but at the end your timer should be the master of your flight times. The fuel count should be secondary check. Seems like the interrupt switch is just over complicated. You're trying to solve when problem (flight time), but creating an entirely new one!

Unless you have an overly large tank a jet is usually close to empty on normal flights with just enough fuel for one or two go-arounds on landing. Therefore actual fuel count is the main gauge and the timer is just a backup. Only two of my jets have overly large tanks and on those I rely more on the timer only because I've had enough by then. At a large rally you may have to wait more than five minutes with your engine running before taking off. Likewise you may not be able to land when you normally would and knowing exactly how much fuel you have left is a god send.

Correct Mark, on all my turbine models the fuel telemetry is the most important information. The timer is just a secondary indication. Back in the day we use to rely on timers, but generally speaking we set them rather conservatively and did not use our onboard fuel in the most optimal fashion. But when one is forced, as I am on this particular model, to optimise weight saving and still get the maximum flight time, then knowing the exact (or very close) amount of fuel remaining, is of critical importance. For what it's worth, I have had many a turbine flight on the same model, where the flight time has varied by 1 to 2 minutes. Mostly because of other traffic, my own variation of throttle use and sometimes due to last moment emergencies or flightline (direction) changes.

....and let's not forget the number one problem with timers - we sometimes forget to activate them!

Cheers,

JanR

I don't think it was mentioned what turbine you are monitoring?
For example on the Jet Central SE turbines, you can reset the fuel gauge by very quickly advancing the throttle from low to high and then back to low, very handy right before take off!

Yes, certainly handy....just don't do that during your flight....LOL

JanR

https://cimg7.ibsrv.net/gimg/www.rcu...28ed4a5dd.jpeg

Neil,

Perfect thanks, exactly as I understood it to be. Just received my Turnigy switch and waiting for an 'always on' TX momentary switch before I put it all in motion.

Appreciate your help - will report back, once I have it all working.

JanR

[QUOTE=Springbok Flyer;12571859

....and let's not forget the number one problem with timers - we sometimes forget to activate them!

Cheers,

JanR[/QUOTE]

Gear up triggers timer ON, simples !!

Works every time ! !

Neil,

I have been trying to get the Turnigy switch to work but no matter what I try it does not switch. Have you or anyone else ever had this happen? To check I have wired a small electric motor with a power source to it, when I add the switch inbetween and have the jumper on always ON it does not run. If I then plug the switch into a working channel on a receiver and operate the relevant channel on my TX the switch still don't work to make the motor run. If I add a servo to the same channel (using a V-cable), the servo work, but the switch does not. If I remove the switch from between the motor and the power source, the motor runs. If I add a manual switch, the motor switches on& off.

The Turnigy switch does not work! I have sent various messages with video's to Hobby King and they don't believe. Any other products out there that may do the same thing? I really like the idea.

JanR

Have you tried the jumper in different configurations?

Yes I have, all 4 the various options. But I have mainly concentrated on the always 'on' option.

I have another to fit later this week or next week, I'll note how I do it and let you know. I do remember needing to reverse the channel on my TX.

I don’t understand...
Surely the whole point of a ground tank is that you push out and start the flight with the tanks full...so the thingy sensor starts from the fuel capacity you have set?? Why do you need to reset when the ground tank capacity is not applicable.

So much complication and more joints added! I would guess there is a greater chance of flame out due to a leak/air bubble than running out of fuel.

Some people don’t get it.....but that’s ok 😄

Yup, let's just keep going - they might catch up...LOL

The thread said reset when using telemetry...you need that to taxi? Bless

I suppose it's possible you have a defective unit (this is hobby king after all) but other than that the Turnigy RC switch works just fine for this purpose when wired correctly. I use one myself and it works fine. I set it up a long time ago but I seem to recall having difficulty getting it to work at first but I can't recall if the unit was defective or there was some peculiarity with the wiring. Items like this that I get hobby king I always but 2 expecting that one may be bad.