235/320/360/Legacy Flush Mount Canopy Latch

[Joel Rogers]

I have redesigned the original canopy latch found in the Legacy's and some 360's to be capable of being installed 100% flush on the exterior of the fuselage. It should be cross compatible with all other models, i am still waiting on more feedback from my post about some specific legacy measurements. Other notable upgrades to the original include:

Weight savings - the version in the photos with every part installed is 7lb 1oz. Version 2 will be roughly 6lb 3 oz & possibly less.

Safety in the event of emergency - all three handles can operate independent of the others. In the latched position someone can still open the canopy from the exterior from either side of the plane.

Improved kinematics - 4 bar linkage now has to overcome 3 separate forces to become unlatched. The original only has force from the over center spring keeping it latched.

There are 4 latches currently being installed, so this post will be the official wait list for the next batch. It will be a few months before I can start on them.
I made almost every part on the originals but will be trying to streamline it some hence the cost. Cost includes choice of Cerakote color from their H-Series line. There is an improved set of install instructions to go with it.

Price with group buy of 4-5 is $1800.

Colors in the pictures are Crushed silver, Stormtrooper White, and USMC Red.

[Paul Miller]

Joel, is your expectation that the Legacy design would not unlock even if the handle were jostled by turbulence or a caught headset wire? I have a mechanical lock primarily because the retractable steps have caused a number of latches to open in turbulence. I would like to solve that issue for the next owner some day. The main goal would be to disconnect the steps from the latching mechanism but that was never designed or tested.

Perhaps the locking mechanism can be latched prior to takeoff and electrically unlatched upon landing? I'm brainstorming here and not saying the lever is moved after landing. I'm saying maybe the safety lock holding the lever is retracted after touchdown so people outside and inside can open the canopy.

I've got the GHA 15 so I know I'm on the ground and airspeed says I've landed (I suppose that works as a signal).

Great work!

[Joel Rogers]

Joel, is your expectation that the Legacy design would not unlock even if the handle were jostled by turbulence or a caught headset wire?

Perhaps the locking mechanism can be latched prior to takeoff and electrically unlatched upon landing? I'm brainstorming here and not saying the lever is moved after landing. I'm saying maybe the safety lock holding the lever is retracted after touchdown so people outside and inside can open the canopy.

Hypothetically yes, this new latch should remain closed even with a fair bit of upset to any of the parts. The way the motion profile of the original latch works (need the measurements to be certain) is the canopy is effectively at its minimum distance to the longerons - i.e. squeezed tight or max compression, at the latch arms maximum travel in the motion path. Any movement front to back results in the latch arms immediately reversing from that maximum. Hence your comment about turbulence & other factors. It would only take about 15-25 degrees before the latch arms are fully disengaged from the strike plate.

The new design puts a cusp in the motion profile allowing the canopy to be latched with an adjustable amount of compression on the canopy seals. In order to become unlatched it now has to further compress the canopy seal before the latch arms are allowed to retract. Think dead bolt on a door where you have to push the door in to get it locked but in reverse. It also uses the seat back as a positive stop in the forward direction preventing any movement, along with 2 additional interior springs for the exterior handles resisting rotation. There is also 35-40 degrees of rotation of the main torque tubes before the latch arms become fully disengaged with the strike plate.

I think it would be fairly straightforward to install a small linear actuator that puts positive pressure on the torque tubes to keep them stationary. It would act in the same way the lock on both new and old designs worked just hooked up to the main panel.

[Shane O'Day]

That looks great!

[Jason Rouault]

Joel, I would love to see some pics and vidoes of the latch once installed.