Control surface Failsafe settings.

[Terry Plumridge 1]

Hi all.

I am building a basic motor glider from Aeronaut. What would be the correct failsafe rudder and elevator deflections.

 

[Ron Gray]

 

but my control surface settings, for all models, are centre positions. For power, I/C reduced throttle, leccy cut throttle.

[Don Fry]

Motor cuts, the CAA do not want it to climb out of the area we operate in. Otherwise a circle glide, or all to neutral, or if equipped, deploy spoilers/flaps.

A turn has the advantage, it doesn’t get so far away.

[andyh]

I generally use whatever the hands-off trim setting are for failsafe, but if you can set a small amount of rudder to make it circle without spiralling in, you might stand a better chance of getting the plane back if you lose radio!  ?

Edited November 4, 2021 by andyh

[Ron Gray]

3 minutes ago, Don Fry said:

Motor cuts, the CAA do not want it to climb out of the area we operate in.

For I/C if you set motor cut and you regain signal you’ve lost your motor, obvs leccy is different. 

[Jon H]

13 minutes ago, Ron Gray said:

For I/C if you set motor cut and you regain signal you’ve lost your motor, obvs leccy is different. 

 

There is also the argument that a running engine at low power can alert a hapless bystander that a model is about to bash them in the head so they can avoid it. 

[Dad_flyer]

That should be a feature of ESCs for electric: set throttle failsafe at below zero, and then the ESC responds to this out of range signal by giving a continuous beeping, using what it does at startup. 

 

Or we leccy fliers should always fit lost model alarms. Make it scream as it comes down.

[PatMc]

49 minutes ago, Terry Plumridge 1 said:

Hi all.

I am building a basic motor glider from Aeronaut. What would be the correct failsafe rudder and elevator deflections.

 

Full up elevator & enough rudder to hopefully make the model spin but it might just spiral, which would be the second best outcome.  

[Rich Griff]

What do free flighted "set/trim" there's to when the engine cuts ?

 

With electric propulsion, you could "restart" the motor ?

 

Not with IC, so a free flight trim, gentle circling....and glide down.

 

Ailerons same but very very small trim else it would spiral in probably, 2 servo aileron, trim as flaps possibly ?

 

No " helpfull" dihedral...

 

An on board alarm sounds good, with its own dedicated battery ?

 

 

Edited November 4, 2021 by Rich Griff

[jrman]

Just set all surfaces to neutral, motor to idle. Anything else is wishful thinking if the radio goes into failsafe when the model is in a roll, loop or anything other than straight and level.

[john stones 1 - Moderator]

Mines always been, servos to center engine to idle, however I will be changing it to down elevator and engine off, priority is it don't fly away and hurt someone, my model costing me a bob or two shouldn't over ride that, if signal comes back, land it deadstick safest I can.

[Jon H]

7 minutes ago, john stones 1 - Moderator said:

Mines always been, servos to center engine to idle, however I will be changing it to down elevator and engine off, priority is it don't fly away and hurt someone, my model costing me a bob or two shouldn't over ride that, if signal comes back, land it deadstick safest I can.

 

I agree that model rescue is somewhat secondary to preventing injury but my only comment against your proposal is than a model in lawn dart mode can punch through pretty solid objects. Even a relatively small model can punch through a house/barn/workshop roof or car windscreen/roof if its in full pile drive mode. Years ago at my first club a 40 size trainer easily punched through the corrugated steel roof of the local farmers barn. A model in a glide, even a steep one, is far less likely to do serious damage if it hits something. Also the glide may give some reboot time to the radio and either prevent the crash entirely or at least make the arrival a more controlled one. The high speed nature of the model in a dive also gives bystanders less time to react and get out of the way. 

 

My models all have their failsafe set for a smidge of up, idle throttle and everything else flat. 

[john stones 1 - Moderator]

Yep, that's why I would want it down asap, hopefully in the field, where those close know the ropes.

 

[Ron Gray]

Like I said, can of wrigglies.

[Denis Watkins]

That can made me smile Ron.

[Don Fry]

The old ones are always the best.

I particularly love the revolving prop safety device. For the technical, solid state memory, to a speaker with a sound. Stuka dive brakes? That ul shift um. 

[Jon H]

1 hour ago, john stones 1 - Moderator said:

Yep, that's why I would want it down asap, hopefully in the field, where those close know the ropes.

 

 

I fly over an active farm field and you can guarantee any model programmed to dive into the earth when the radio fails will do so over someone's head. Stuffing a model through the top of a tractor is not a nice idea. Its like midair collisions only ever happening when there are 2 models up, its just the way it will go.

 

A better choice would be full elevator and rudder to put it in a spin as the rate of descent would be far slower and it would still fall more or less vertically. 

Edited November 4, 2021 by Jon - Laser Engines

[john stones 1 - Moderator]

No guarantees Jon, you make your choice and hope for the best. If car wasn't off road I'd take Rons worms n go fishing tomorrow.

[Martin Dance 1]

I think everyone accepts that the primary reason for the use of fail safe on our models is to prevent models entering controlled air space. So setting engine to idle or cut will ensure that happens. It's the next bit that is open to discussion, what then. I would suggest a slow descent is best. So as Jon suggests a smidge of up elevator is probably the least worst option. Assuming the model enters fail safe in a more or less upright and level attitude it will slow down a bit and should it encounter something on the ground either your land lords Roller or some other soft machine with luck the damage will cost less than six figures to fix. I would suggest that trying to induce a spin is probably the worst thing to do. Many models if placed into a spin which is allowed to develop beyond 3 or 4 turns tend to drop their noses and the rate of descent increases dramatically. Also consider what will happen should the model enter fail safe whilst in a steeply banked turn or inverted . A little up elevator in those situations is almost certainly the best option.

[dave windymiller]

I had a model that briefly went into failsafe due to distance and having the transmitter aerial pointing towards the model.  The engine went to idle but i thought it had cut. As i leaned on the sticks to glide it back i realised nothing was happening.  The motor then sprang back to life and the control surface jumped to the ever increasing stick movements.  This caused it to flip and it went in at full throttle.  I now go for engine cut for failsafe. 

[Don Fry]

7 hours ago, Ron Gray said:

 

but my control surface settings, for all models, are centre positions. For power, I/C reduced throttle, leccy cut throttle.

Bump.

[PatMc]

The OP specifically asked for the rudder & elevator failsafe settings he didn't mention the motor. From the image in his post the model is clearly an electric powered motor glider.

A near vertically descending model is much less likely to hit a person or structure than one descending at a glide angle. It's also less likely to enter the airspace of any man carrying aircraft.

[Jon H]

2 hours ago, john stones 1 - Moderator said:

No guarantees Jon, you make your choice and hope for the best. If car wasn't off road I'd take Rons worms n go fishing tomorrow.

 

Nothing is certain that is for sure. Im just of the firm belief that time is a critical component in an emergency situation. If you can slow things down there are often more avenues to explore. Also i tend to fly a long way off, up to 400m or so either side of myself and i have no way of knowing who or what i am flying over. The longer the model is in the air the more chance there is to rescue it and while rescuing the model is not a priority on the one hand, it is a priority if that rescue prevents the crash in the first place. If i can get the model back under control and back to the runway or navigate it to a safe place to ditch it, that to me is a much safer option than having the model bury itself at the first sign of trouble. If you fly close to a busy road then perhaps its a different story, and most of my models are heavy metal scale stuff so they wont go far on idle throttle anyway so a glider or something might need another approach. But generally i would always seek to give myself as much time as possible to rectify the situation and prevent a crash if at all possible. 

 

 

 

 

[Jon H]

13 minutes ago, PatMc said:

 

A near vertically descending model is much less likely to hit a person or structure than one descending at a glide angle. It's also less likely to enter the airspace of any man carrying aircraft.

 

It might be less likely, but its more likely to do substantial damage to what i does hit. 

 

As for the full size airspace issue, is that really likely? Everyone is in general agreement that power to the model would be cut, and most models will come down quite rapidly in that instance and most clubs are by their nature a long way from full size activity. Major roads would be more of a concern than full size traffic as models should be operating well away from them anyway

[Frank Skilbeck]

6 hours ago, jrman said:

Just set all surfaces to neutral, motor to idle. Anything else is wishful thinking if the radio goes into failsafe when the model is in a roll, loop or anything other than straight and level.

Not on a lightweight electric glider I wouldn't otherwise you might never see it again. Friend had a free flight chuck glider at our club site set to do a gentle circle, last we saw if it was 3 fields away still going up in a big thermal. I also managed to bungee launch my Easy Glider without switching the Rx on, it took ages to come down, just as well it didn't catch a thermal.

 

But I can count the number of fail safes I've had on 2.4 on the fingers of one foot ?

Edited November 4, 2021 by Frank Skilbeck