I have a Spirit Gt installed on my Trex 550E.
Everything has been working as it should and quite happy with its performance.
Except the other week.
I bring the heli to altitude and activate Auto Recovery at 25 feet, verified with my Vario meter. As always I test the sytem prior to flight. It is working as it should and as it has in the past.
I was practicing upright hurricanes and lost the heli in the sun. Tried not to move the sticks till it emerged and I regained sight. When I did noticed heli was off to my side, upside down and about 4 feet from the ground. I immediately hit throttle hold. Obviously ended up with damage to my heli. This should not have happened and is the whole reason I have this system is to automatically stop the heli from crashing into the ground.
Can anyone explain why this happened and how to prevent it from happening again?

Finally got all the necessary repairs completed.
Went the the field for some flights.
Auto Recovery is still not working properly.
Switched on auto recovery at 30 feet, while in a hover. Then tested it and seemed to be working. Then it wasn't. Heli was well below the hard deck at about 15 feet. I had to disenage then re engage the auto recovery to save the heli.
Sure would be nice if someone could help explain why it is no longer working as it was or as it should be.

Hey there,

Were you using Spirit Units Altitude Limit or the geolink function? The geolink one is currently not reliable, updated Firmware is expected to be available soon - See viewtopic.php?f=20&t=5325

Also: Were you using the acro stability Mode or normal one? I dont fly 3d, but to my knowledge the "normal" one doesnt Support skids being upside down.

Sorry for your crash, hope it wasnt too expensive to repair.

Cheers

Hello,

if you are flying 3D maneuvers then good altitude for Automatic Rescue is to set to at least 50 feets.
Difference between 25 and 15 feet is very low for some maneuvers. If your model is flying in a knife edge flight or it is flying really fast under angle then there is only very small chance it will trigger the rescue.
When model is flying fast then pressure created by the rotor can be easily very different. And the unit is measuring the altitude from pressure.

So to avoid such problems please set the rescue level as high as possible. Then you can test all possible maneuvers and verify at which altitude the model will react. So then you will know what altitude is suitable as rescue level for you.

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Spirit System developer

Thanks for your condolences. Repairs were main and tail blades, front and rear gear sets, and since its an older heli (550E), the rear gear set didnt fit so had to update the entire rear assembly (gear case, gears, shafts, sliders, hub, grips, whole kit and kabodal). Starts adding up pretty quickly.

Was using auto bailout feature which is within the GT unit itself.

Thanks for the reply and info.
Yes I was practicing upright hurricanes. Guess that can be classed as a 3D maneuver? Heli was on an aggressive side angle attitude with what I would call medium speed.

So if I understand you correctly, the auto bailout feature is uneffective in such aggressive attitude and speed maneuvers? I do have the geolink on this heli as well. Would using lower attitude limit be a better safe guard?

... this is what you have to find out for your heli and some special maneuvers. flight direction, speed and pitch angle can have effects on the air pressure measured by Spirit unit (depending on canopies too). thus height calculation could be off by some meters during fast and/or demanding maneuvers. you can do such tests with checking height telemetry log (or live telemetry) vs. those maneuvers too.

in addition there is mechanical and aerodynamical lag in the reaction too... depending on many factors like downwards speed, headspeed, etc etc etc. so it can take some meters downwards until the heli reacts on already 'fired' rescue. i.e. a rescue from a fast tail slide can take some 3-5 meters easily after being 'fired' until the heli starts climbing with lower headspeeds (can be i.e. checked in the logs when comparing bec amps/voltage that show when rescue is fired, motor amps that show when the rotor disc comes under load and height graph that shows heli reaction). in general it is working great on all of our helis... but there are of course (physical & aerodynamical) limits to be respected.

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cheers
Michael