"Questions for the latch designers:
Will the secondary latch engage automatically on closing the canopy?
If not then you're adding to the checklist.
"How far will you have to close the canopy for the secondary latch to engage?
I see limited efficacy if you have to close it farther than the point
People prop open their canopy for ground ventilation.
""Will the secondary latch be operated by the primary lock handle?
This would be ideal.
Can the secondary latch be released from outside the cockpit and will its
Operation be obvious?
In my mind, the answers to these questions are critical. I won't use a
Latch that doesn't allow immediate and obvious ingress in an emergency."
These requirements and more were on the initial requirements list. Working with a small team, John Smith has compiled about 25 different ideas and variants. Most focus on requirements first, then simplicity, then means of attachment. General approach:
- Latch is on top of canopy with simple striker plate on fuselage arch
- It latches while the canopy is still open a bit but latches into place when you release canopy you are holding open with your hand.
- Pilot or copilot applies single upward motion to lift canopy at center with upward facing palm of hand applied to a small forward facing lever that disengages latch when you push up. So getting out is 1) release main latch and 2) reach up, push up on canopy at center which means your palm will push up on the internal lever, and canopy opens.
- A penetration through the arch to the outside engages a flush or nearly flush lever outside on top that can be pulled up from outside. Rescuer approaches plane, side latch is released, canopy can be raised an inch or two, hits secondary latch, but external lever is clearly visible to untrained outsider who can immediately detect what is still holding the canopy from further motion, sees the lever, pulls up on lever, canopy does its final release and swings upward. Think of it as similar to a hood latch that has its release on the top surface of the hood.
Other requirements (must haves) and desires (nice to have) welcome. John is a very busy boy, on the road a lot, so I am providing first response, but he is the leader of the team working this problem in Australia. Current questions focus on attachment methods to canopy and fuselage arch, and have been submitted to Lancair. With some guidance on approved attachment methods and locations, we can narrow the options and present to this group for review.
Fred Moreno