IV door latches

[jonstark]

The original door latches at the middle of the forward door post seem secure but leave a bit to be desired. The factory would have to manufacture then powder coat a set of the new style with about a month lead time.

Have any of you imagineered your own door latches?

Jon

[jonstark]

Murle Williams Aviation has just the ticket!

[rv9ralph]

I fabricated door latch for my Model 3 using 2 inch aluminum angle stock. Trimmed to a kind of teardrop shape with one on inside and the other on the outside. Works great. Sorry no pics, plane is 2 states away for the next several months.

Ralph

[Guy Buchanan]

Here's one in the fine tradition of homebuilding; ridiculously expensive, overly complex, but works well and looks good. It starts with a door pillow block from Murle, then replaces all the rest of Murle's latch with a bent aluminum bracket bonded to a turned aluminum flange. Onto that is screwed a stock ball. The bracket is loosely screwed to the pillow block with wave washers to give it some resistance to turning, and the bolt is a hex head accessible from the outside, so you can "lock" it. On the aircraft side is a polished delrin block designed to ramp the door closed and provide a recess into which the aluminum bracket drops with a soft "click".

[Delta Whisky]

This may be something of a hi-jacking experience - but, since you mentioned door latches . . . . .


I can't tell what the Murle Williams Aviation door latches look like and because I'm not convinced the single, center latch is the best way for me to go, I've played around a bit with a concept that worked well on a glider of a past life and prototyped a proof of concept. Because I don't have any experience with the newer versions of a Kitfox I thought I'd ask for your honest opinion, thoughts and recommendation for either improvements or which trashcan to use (I really don't want to spent more time working on an idea that you know has severe limitations.)


This will latch the door frame at front and back and barely protrudes into the person space in the cockpit - two of the design requirements. So, here's the proof of concept in a rough form - your inputs are requested. In the next iteration, if there is one, I'll lower the operating bar 0.2 in and shorten it 1 inch.

[PaulSS]

I have to say that if I were going down the road of rods I wouldn't complicate it as much. I'd have the latch at the front of the door, which would overlap the door frame as they currently do (onto a striker plate) and I would have a single rod on the same latch that would travel within the door frame itself and then engage in a hole at the rear of the door.

Excuse the crappy hotel paper and poor drawing skills, but something like this maybe:

[avidflyer]

Guy, Once again, I wish this site had a like button on the posts. I would like yours. Very nice. This will have to do. JImChuk

[efwd]

The latch that came with my airplane is the same that Stick and Rudder has. I never noticed a thing with regard to the door being insecure.

[Dave S]

Darryl,


We have an early model S7 which came with a double pin latch of a similar principal to you are considering; however, with a slightly different approach.


You can' see the rear pin in the photo due to the seat cushion but it is similar to the front one.



The door lock was my addition, not part of the kit.


I will say the double pin does keep the door gasket firmly in contact with the door - maybe I see that as a good thing in the winter up here.


Certainly a few more parts and some additional work to install.

[PapuaPilot]

Thanks Dave.

I have the same two pin as you do and have never gotten around to installing key locks. You picture is both a reminder and shows a very easy way to do it. :)

[Dave S]

Phil,


What made the locks particularly easy was the fact that the locksmith had these in matching cylinders so both doors use the same key; and, the lock kit came with several arms of different offsets so it was super easy to match the arm with the latch. If I recall, the local locksmith called these "Cabinet drawer locks" and the cost was less than $20 for the pair - of course that was a few years ago:o.

[DesertFox4]

If your door latch looks something like this, you’ve probably over engineered it.
16189

[efwd]

That's Funny! :D

[Delta Whisky]

Thanks for the inputs - especially DesertFox4 - yours keeps the challenge at the forefront.


Dave - I like yours because it adds easy access from the outside and a lock. I'm not sure if the lock component can easily be included in a bubble window door. I'll have to make a phone call and see if any are still available.


If anyone has an approach to a front and aft lock design - pictures would be appreciated.


Thanks again.

[Av8r3400]

Mine are a little more crude, but I wanted to latch in two places...

http://www.avidfoxflyers.com/uploads/monthly_02_2013/post-36-13607294491864.jpg

http://www.avidfoxflyers.com/uploads/monthly_02_2013/post-36-13607294572925.jpg

[avidflyer]

Those who fly when there is snow on the ground want the doors to seal up, don't they Larry. JImChuk

[Clark in AZ]

Has anyone considered rare earth magnets in the corners with a normal center latch?


Clark

[PaulSS]

I think rare earth magnets would magnetise the airframe over time and could cause trouble with the compass and possibly any magnetometer that may have been installed. Of course, you could degauss the aircraft but that sounds, to me, like it's more trouble than it's worth.

[HighWing]

The single latch on the IV has been standard from the beginning with the exception of the "Double Pin Door Latch" that was offered for a while as an option. Unlike the ones pictured in the thread, this one was mid door and was not well received. I think there are significant differences between the IV and the 7 that eliminate the need for the two pin. Primarily due to the following: The flexibility of the tubular aluminum door frame with a fiberglass or Lexan panel on the lower half - If gapping is an issue bowing the lower tube will bring both ends firmly against the exterior. There is no aluminum door seating structure requiring a precision fit and the fiberglass or Lexan covering of the lower door panel overlapping the fabric provides the seal. What Guy Buchannan did is essentially what you will find in almost every Model IV. I had the same type on my first IV - 900 hours over 9 years and on my new IV - not so many hours. Although the basic design is the same, there can be variations in the details. The following pictures are what are in my current airplane. One note: I decided that an external handle for the passenger side was not necessary because that door was seldom opened first. The passenger door only has an internal latch for opening especially for the purpose of emergency egress if necessary. Rather than having a structure that raised the pivot above the door frame, I drilled through it for the pivot - 3/16" and used half steel tubing hysoled in place to beef up the frame there a bit. My lock idea was very similar to Guy's as well.