Occupancy Sensor

[rwanttaja]

I've had two cases on my Fly Baby where I've left the master out and smoked the battery. I've been contemplating adding an "occupancy sensor" to note when the master is on, but the aircraft is unoccupied.

I'm looking for ideas on how to sense when there's nobody in the seat without using a sensor on the seat mount or the seat itself.

I may try to hook a magnetic switch that senses when the stick is aft of the full-down position (gravity moves the elevators down when no one's holding the stick). Might be able to rig a switch to the floorboards, or a light/reflector system that has a beam broken when the legs go into the under-panel area.

Any ideas?

The "Alert" portion of the system is still under contemplation. I changed my shut-down checklist to ensure power's off, but find my close calls recently have been when I've turned the switch on to work on the airplane. So I'm not going to add an obnoxious hooter; more like something that chirps every fifteen seconds. Maybe just a damn bright LED.

Ron Wanttaja

[Sam Buchanan]

My RV-6 has a large red "Turn OFF the Master You Idiot" light that is wired through an oil pressure switch. There is also an audible alarm (which can be turned off for maintenance) on the same circuit. No need to ask why I decided to add this feature.....

[Frank Giger]

I like the idea of a small bright LED right above the switch, tied to the battery master.

That way a quick look either in or out of the aircraft will show its position.

Or you could hook an electric buzzer to it. I don't know the decibel levels on these things, but that's the extreme solution.

Frank "my electric fuel pump is my buzzer" Giger

[DaleB]

Low voltage alarm. Set it to beep/flash if the bus voltage is below 13-something Volts. It will go off any time the master is on and the engine isn't running. For extra credit, a 30-60 second delay makes it less annoying.

[rwanttaja]

Some good suggestions.

I like Dale's suggestion of using the bus voltage as the trigger point. The only (very minor) issue is that my generator-type system doesn't go above 13 volts until the engine's turning up 1800 or so RPM. But that's not an issue if I have a low-key chime-type warning...ain't gonna hear it with the headset on, anyway.

I have contemplated putting a big light to come on with the master. I spent beaucoup bucks for a fancy light-up toggle switch for the avionics bus (well, $2 more, anyway) and that light just doesn't really show up outside on a nice day. But my main worry is with the plane in the hangar, and in any case, I live in the place where the sun doesn't shine (Seattle).

But... I'm actually leaning towards putting the light on the OUTSIDE of the airplane. My thought is a big mondo LED pointed out of the left side of the fuselage. That's where the toolbox, workbench, and FBC (frosty beverage cooler) reside. As I mentioned, my main concern is leaving the main switch on after performing maintenance. So I'd aim the light at the places I'd likely be before departing the hangar.

I'm planning on doing some minor electrical reworking over the next few months, I'll keep folks apprised of what I end up with.

Ron Wanttaja

[Sam Buchanan]

Put a strobe (flashing LED) on the vertical tail. Now you have a "turn off the master" reminder and an anti-collision light.

[Kyle Boatright]

I have a little audible device that is tied to the master. If the master is on, there is a 78 (or is it 72?) dB tone coming from under the panel. The sound is loud enough to notice with the engine off, but the engine drowns it out.

[Bill Berson]

Like Sam said. I just left the stock strobe switch on at all times. I could hear the strobe firing in the cockpit when the engine was off but with the master still on after parking.

[Joda]

Like Sam said. I just left the stock strobe switch on at all times. I could hear the strobe firing in the cockpit when the engine was off but with the master still on after parking.

Yep, this is what I do as well. If the plane has strobes, or even a beacon, just leave that switch on all the time. If you don't notice the flashing lights after you get out of the plane then you've probably got bigger issues than just leaving the master on!! :)

But if the plane doesn't have anti-collision lights, you can just imply wire a small lamp into the mater circuit that is on anytime the master is on. We've done this with several planes around these parts. It seems to have worked very well.

[CarlOrton]

C'mon, Ron, put a bit of a challenge to it! Set up an IR emitter / detector pair on each side of the cockpit. If you get out and the beam completes, then set off an alarm. Small, simple, and relatively cheap. Plus it gives you something to talk about at fly-ins!

[rwanttaja]

C'mon, Ron, put a bit of a challenge to it! Set up an IR emitter / detector pair on each side of the cockpit. If you get out and the beam completes, then set off an alarm. Small, simple, and relatively cheap. Plus it gives you something to talk about at fly-ins!

Actually, this is the way my mind originally turned. Thinking I could put a emitter/detector pair on one side, and a white surface on the other as a reflector. Got a laser LED element floating around here somewhere.....

Have to admit, I have a Rube Goldberg tinge that wants something not completely simple.

The airplane HAS a strobe, but it hasn't been hooked up for about 10 years. Ran out of panel space/enthusiasm for switches/fuses when I re-did the electrical system. Ditto the nav lights. Dates to the building of the aircraft ~40 years ago. Hardware-store wire used; not too fired up sending strobe pulses ~10 feet through it.

The strobe itself is mounted to a big shaped balsa block on the vertical stabilizer...totally ruins the lines of the tail. I've temporarily removed it, in the past, to mount a video camera instead.
http://www.bowersflybaby.com/pix/video_tail.JPG

I tend to cover it in shame, on the ground....
http://www.bowersflybaby.com/hat.jpg
Ron "Good place to keep the formal flying helmet" Wanttaja

[Sam Buchanan]

The airplane HAS a strobe, but it hasn't been hooked up for about 10 years. Ran out of panel space/enthusiasm for switches/fuses when I re-did the electrical system. Ditto the nav lights. Dates to the building of the aircraft ~40 years ago. Hardware-store wire used; not too fired up sending strobe pulses ~10 feet through it.


"Strobes" are so obsolete. :)

eBay is stocked with all sorts of bright, flashing LEDs that only require low-current 12v power. Much smaller, self-contained, often brighter, and far less power required (no power supply) than the old-school stuff. The present wiring should work just fine. Looks like you could keep the camera, just replace the position light with LEDs. Or better yet....ditch the strobe nacelle and keep the position light housing...that FlyBaby would no doubt be much sleeker and faster! :rollseyes:

[Bill Berson]

Strobes were always obsolete, I think. (don't do much in daylight) (not needed at night) In my opinion.

[Sam Buchanan]

Strobes were always obsolete, I think. (don't do much in daylight) (not needed at night) In my opinion.

I was contrasting xenon-filled glass tubes with fancy new LED-thingies........

[rwanttaja]

I was contrasting xenon-filled glass tubes with fancy new LED-thingies........

Last time I flew was a typical Seattle winter day... about 45 degrees, cloudy. I was following a 172 into the pattern, and remember marveling at how visible the plane's strobes were. One on the tail, one on each wingtip. I'm sure they were the modern LED type...they were blinking, not flashing. Wouldn't mind adding something like that. Just don't like the ugly protuberances on top of a shapely tail.....

Ron Wanttaja

[Bill Berson]

I was contrasting xenon-filled glass tubes with fancy new LED-thingies........
Agree.
The highway patrol has some very bright and dazzling LED in red, blue, yellow and white, I think.

[Frank Giger]

The super Rube Goldberg in me (and my method for building is 1. come up with a plan, 2. Find five elements in it that can be removed, 3. Wait, 4. Go back and remove three more.

So I'm wondering if a pair of garage door sensors and a bit of circuitry from the opener hooked to an LED light wouldn't do the trick?

[DaleB]

The super Rube Goldberg in me (and my method for building is 1. come up with a plan, 2. Find five elements in it that can be removed, 3. Wait, 4. Go back and remove three more.
In that spirit... how about a big sign taped to the wall of the hangar, next to the light switch or door or whatever is the last thing you do, that says:

MASTER OFF?

My wife put one in my hangar to remind me to make sure I leave with my cell phone, glasses and keys. Sucks to lock those up in the hangar.

[planecrazzzy]

How bout re-keying a switch to your "car key"... Can't leave unless you have the key ?
I've re-key'd several locks... Just put the key in an file what sticks out.
I've also moved the little pins... but filing is easier.
.
Simple , but... you'd have to drive the same vehicle to the hanger

OK... Revision... Put the master key on a ring WITH your car key... or hanger key...
Hmmm, now you can't get back in the hanger to shut off the master !!!! HA...

.
Gotta Fly...
JAM

[CarlOrton]

Good thoughts, JAM, but for some, experimentals especially, (like my Sonex) the only keyed device was the padlock on the canopy! And, since I was in a hangar, I never used the padlock.

[cluttonfred]

I like the idea of wiring a low current draw LED strobe directly to the master circuit with no switch, just a fuse you can pull if you want to shut it off while working on the plane, pretty hard to miss, and you can lose the big strobe and the nav lights and the unused wires. These look good, much cheaper than the aircraft type, mounted through a hole with the rubber grommet or on the surface with the flange mount, draw 1.2 amps, about 4 cm diameter and 3 cm high: https://www.superbrightleds.com/moreinfo/strobe-beacons/led-hideaway-strobe-lights-mini-emergency-vehicle-led-warning-lights/1905/

6979

[cub builder]

You could try this new concept developed by the government. They call it a checklist. It has been known to help folks to remember little details like mag switches, master switches, etc. It does require a certain amount of self discipline which I apparently lack. :D

FWIW, On the occasion that I leave my master on and kill the battery, it's almost invariably not after flying, but after doing some kind of maintenance work; typically avionics where I've had things powered up for a while, then forget to shut off the master. Or, I was demo-ing my latest whizz bang avionics toy for someone and failed to turn off the master. Invariably, I don't find it until the next preflight right before I plan to launch. :mad: That's the one time that any of these Rube Goldberg fixes (including checklists) fail as I would invariably get annoyed by the flashing strobes, LEDs, or noise makers during a demo or maintenance and find a way to defeat them while I'm working on the plane or demo-ing a toy for someone.

My personal methodology as a pilot is to ensure all the switches are off and I scribble my tach time onto my clipboard before I release the belts. Once it becomes habit, it works in every plane, no matter what you fly. However, I have never developed a method to reliably remember to shut off the master after maintenance or after reaching into the cockpit to demo some piece of equipment. Man, I hate it when I'm at an Fly In and show something to someone, then come back the next morning to find myself with a dead battery. Yes. I have done that.

-Cub Builder

[rwanttaja]

You could try this new concept developed by the government. They call it a checklist. It has been known to help folks to remember little details like mag switches, master switches, etc. It does require a certain amount of self discipline which I apparently lack.
But just like you, most of my near-misses have been in case where checklists DON'T help... casual, informal, working around the airplane after the flying is done.

My first case was a post-flight failure...and I did change my shutdown procedure to reduce the chance of recurrence. But it doesn't help if one is just fiddling with the plane. I'll admit going a bit OCD since I burned out a second battery in one of these instances. I do tend to check the switch position several times before leaving the hangar, and have driven back to take a last look. Just looking for a set of suspenders to go the belt I've added to my Sansabelt pants.

Ron Wanttaja

[conodeuce]

One possibility that is relevant only if you also use a smart phone (iOS / Android): wire a small RFDuino-based device under your panel. It's a 3-volt, super low current device. Small custom app on your phone communicates over Bluetooth with the RFDuino. Alerts you if the power-down cycle hasn't occurred. I build little apps like that; so, I could walk you through it. I'm based north of Seattle in Anacortes.