Canopy Open Switch, Slider

[lrfrey]

I've searched the archives and cannot find a mention of folks putting a switch on the sliding canopy to illuminate a light if the canopy is not locked.
I'm sure I saw one somewhere.

Anyway, that's what I would like to do on my 7A slider, but am having trouble figuring out how to mount a switch at the lock point. Any suggestions appreciated.

Larry

[Rick6a]

Hi Larry,

How timely! I just walked in to take a break after starting a canopy lock warning light installation on the -8. This morning, I visited the local Radio Shack and bought a four pack of NC switches. I am going to use one with a "Legend Light" available at Spruce as part of a 6 light annunciation panel.

http://www.aircraftspruce.com/menus/el/lights.html

The NC switch is mounted on a simple bracket attached to the rollbar/sill with flush Cherry rivets. The switch will open (turning the light off) when the canopy is slid forward and the nylon wheel inside the canopy track comes into contact with the switch. I positioned the bracket so the canopy latch has to be engaged on its mating roll bar nipple before the switch is (de)activated. Anyway...that's the theory.

How you coming along? Haven't seen you since our little road trip to Jeff City a few years ago.

[AlexPeterson]

Originally Posted by lrfrey

I've searched the archives and cannot find a mention of folks putting a switch on the sliding canopy to illuminate a light if the canopy is not locked.
I'm sure I saw one somewhere.

Anyway, that's what I would like to do on my 7A slider, but am having trouble figuring out how to mount a switch at the lock point. Any suggestions appreciated.

Larry

Mine will rattle, move, shake etc. if I even try to do a runup with it not latched. I can't imagine the noise if one went to takeoff power with it unlatched. In my case, no warning light is needed.

I usually latch it before doing runup, but if it is hot, and there is a delay prior to takeoff, I'll often do a runup without latching it (just slide it forward). I've never worried about trying to take off without it latched due to the racket it makes.

What have others found?

[Ironflight]

Originally Posted by AlexPeterson

What have others found?

I think that the -8 maybe different because it is narrower and hence more rigid Alex. I know that early in -8 flying career, I got into the takeoff roll with the canopy unlatched due to other distractions. Yeah, if it was pushed back, you would not have a prayer of missing it - but if it is within an inch (underneath the fiberglass windshield bow), the difference between that and "closed" is not so great. I finally developed a habit of putting my hand on the latch just before opening the throttle, and haven't missed it since.

Paul

[Rick6a]

Originally Posted by AlexPeterson

.....I usually latch it before doing runup, but if it is hot, and there is a delay prior to takeoff, I'll often do a runup without latching it (just slide it forward).......

Alex,

You just described the exact scenario I experienced in my -6A. I found there is not a whole lot of difference in engine noise with the canopy forward but unlatched during takeoff. After leveling off and throttling back, I noticed that things just did not seem right and then discovered the unlatched condition. It was during that early flight that I quickly discovered even during slow flight that you cannot move that canopy one way or another if you wanted to and I tried over and over. In that sense, a canopy lock warning is superflous I suppose, but I still want one.

Yea...right, I'm the first ........I'm sure if others are honest about it and admit to taking off with the canopy unlatched, they will report a similiar experience.

[lrfrey]

Thanks Rick, excellent solution. I was thinking put it up on the rollbar/latch itself, but after hearing from you guys I see no need to. I'll put it where you did an go.

I'm getting there, I was thinking she would fly this fall, but it's starting to look more like spring now as I decided to paint before flying. Drop by one of these days, 3K6, I'm there most days.

Larry

[az_gila]

Originally Posted by Rick6a

......
How timely! I just walked in to take a break after starting a canopy lock warning light installation on the -8. This morning, I visited the local Radio Shack and bought a four pack of NC switches.
......

Rick,
Typically, Radio Shack switches have a pretty low reliability.... ...and probably don't have a DC amp rating...

You might be better of using true Microswitches (made by Honeywell) for this application, similar to the gear switches in certified planes.



This is an unsealed version, but should be OK if it's under the canopy away from any possible water entry. Sealed versions are available. Each switch has both NC and NO contacts.

They are not very expensive, and can be bought at Mouser...

http://www.mouser.com/catalog/631/1346.pdf

This Allied Electronics page give the DC contact rating, at 5 Amps it should be able to drive your lamps.

http://www.alliedelec.com/catalog/pf.asp?FN=969.pdf

If you are going to the effort of putting in a warning system, it should use reasonably high reliability components.... having warning systems operate at the wrong time is very annoying....

I intend to install a similar switch on a -6A tip-up canopy....

gil in Tucson

[thallock]

I think I have a simpler solution to this problem. Put an entry in your checklist that says "Canopy closed and locked". Very simple, relatively reliable, and very little weight.

Rick, I have some of those switches from Radio Shack. Not for use in my airplane, but for experimentation. No offense, but they can best be described as junk. There's nothing wrong with your installation, just get some better switches. You have about as much probability of not getting an indication using those switches as you do of forgetting to close the canopy in the first place.

Tracy.