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Advice on an RV-4 canopy latch?

poppadok

Member
I’ve been searching past posts trying to find either plans for building or a place for buying a latch that holds my RV4 flop open canopy open a couple inches for taxiing, but am having no luck. Could someone point me in the right direction please?
 
I’ll try to remember to take a picture of the gizmo I made for this purpose. Very easy to make, and it works. Every RV4 is a little different, so it may not work for you. My first RV4 had a second hole drilled in the instrument panel above the original one that holds the canopy slightly open for ventilation. My current RV4 had a little different geometry and that didn’t work, so I made this gizmo. I’ll take a pic and connect it to this thread.
 
I drilled holes in panel and rear bulkhead about 2" above locked position holes.
Yes, does require locating the tubes inside of instead of in the square canopy frame tubes. (Picture from RV-3 but did same in RV-4). In RV-4 the bracket can be forward of the canopy frame.

Finn
 

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I've been collecting photos and screengrabs of canopy hold-open features for the -4 for years, but have yet to find or devise anything I like.

I keep in a PowerPoint file for easy reference. If you would like a copy, send me a PM with your email address and I will send you the file. If you build one for your canopy, please post pictures!

Good luck,

Dean
 
The nicest solution I have seen is in the two attached pictures. All I have seen are the two pictures but it looks like the way it was designed to work is when the canopy latch handle is in the spring loaded closed position (3/8”canopy latch tubes extended fore and aft) the pin that is part of the stainless steel weldment that replaces the aft canopy latch tube (C-408) engages the stainless latch in the partially open position. The added benefit of this design is that if someone were to allow the canopy to close without rotating the handle against the spring to the open position it would engage the latch before the canopy latch tubes made contact with the fuselage at the forward and aft ends of the canopy. This is something that can happen easily if you don’t properly brief anyone who may attempt to close your canopy and there are many RV-4’s out there with the scars to prove it. I wish I could take credit for this, but I stumbled across these pictures after I had already completed my hold open feature. I will send what I did in a separate post to give you another option that is simpler to fabricate but maybe not as feature rich as this one.
 

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I made mine out of two plates and a piece of angle. The angle is secured by the roll bar left attach bolt and provides a pivot for the two plates. One plate has a “U” shaped saddle (partially hidden in this picture) and the other serves as a latch. The latch and saddle are spring loaded (small steel spring is hidden in this picture) out of the path of the 3/8” canopy latch tube. When I want to engage the latch, I reach around my left shoulder and rotate the latch and saddle into the path of the 3/8” canopy latch tube as I am closing the canopy. The tube lands in the saddle and is secured by the latch. There is a nylon washer between the saddle and latch plates at the pivot to minimize rubbing between the two plates. To release, I reach back and rotate the latch to allow the tube to come out of the saddle. As you can see, I use a few small rubber bands to position the latch relative to the saddle. I have a step in my condition inspection checklist to replace the rubber bands every year so they don’t dry out and I dab a little white lithium grease between the plates to keep everything operating smoothly (not sure what I will do when both my kids are out of braces). Also, there is a short piece of clear shrink wrap on the 3/8” tube to protect the paint. After 4 ½ years of flying I have been pretty satisfied with how it works. I hope this helps. Lot's of improvising in the RV-4 world particularly as it related to the canopy.

Stan Watts
RV-4 SN2900 (N824SW) - Builder/Flyer
 

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Thanks everyone, these ideas are. Very helpful! I’ll peruse the PowerPoint, compare to these, make one up and let you know how it turns out!
 
The nicest solution I have seen is in the two attached pictures. All I have seen are the two pictures but it looks like the way it was designed to work is when the canopy latch handle is in the spring loaded closed position (3/8”canopy latch tubes extended fore and aft) the pin that is part of the stainless steel weldment that replaces the aft canopy latch tube (C-408) engages the stainless latch in the partially open position. The added benefit of this design is that if someone were to allow the canopy to close without rotating the handle against the spring to the open position it would engage the latch before the canopy latch tubes made contact with the fuselage at the forward and aft ends of the canopy. This is something that can happen easily if you don’t properly brief anyone who may attempt to close your canopy and there are many RV-4’s out there with the scars to prove it. I wish I could take credit for this, but I stumbled across these pictures after I had already completed my hold open feature. I will send what I did in a separate post to give you another option that is simpler to fabricate but maybe not as feature rich as this one.

Hi Stan,

Thanks for these photos. I agree - this looks like the best execution I've seen too. I believe I saw this one or something very similar quite a while ago - before I had started to archive the photos. This one looks hard to build as much of the geometry would have to be developed by trial and error. If drawings exist it would be a great head start.

Thanks again,

Dean
 
Went flying today and took a few more pix. I agree Dean, probably a good bit of trial and error went into making that all work right. Some nice looking TIG welding too. Tip of the hat!
 

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Hi Stan,

Thanks for these photos. I agree - this looks like the best execution I've seen too. I believe I saw this one or something very similar quite a while ago - before I had started to archive the photos. This one looks hard to build as much of the geometry would have to be developed by trial and error. If drawings exist it would be a great head start.

Thanks again,

Dean

Following!
 
I made a small bracket to hold my canopy open slightly for ventilation on the ground. It fits into the forward canopy latch tube hole in the instrument panel using a hardware store bolt, washers, and nuts with the threads covered with a couple layers of shrink tubing. The hold open hole on the bracket has an appropriately sized snap bushing in it. Pictures tell the story. Works very well, and obviously easy to make:

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I did something similar to Scott for my RV-3. But it stays in place and pivots out of the way to close.
 
Canopy Hold Open Latch

This not as elegant as some of the other options I have seen posted, but I submit that I prefer the canopy to the secured on the leading edge at least. I worry about the prop blast during run up causing the canopy to flex if only secured in the middle with a single latch. I can see that the canopy is secured without craning my neck to check it. Admittedly, my canopy is not raised than high but there is still adequate airflow. I may be the only one that does my run up with the canopy cracked open however.
 

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Pat Hatch needs to chime in on this..

Pat Hatch (on VAF) , had the nicest hold open I've seen on his -4. One of these days , I will get around to building the same type. It has a pin that articulates into the roll bar, all actuated with the standard locking handle. The unit is attached to the canopy cross member. I dont have post worthy pictures, but perhaps Pat will chime in with some.
 
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