FHC: How many latches?

[rnbraud]

Hello all, again,

 

The Front Hinged Canopy build continues. Now that I have a plan for the canopy seal,

I need to plan for the latches.

 

Rock's Thinking: Side Opening Canopy: I understand the need for three latches with the standard Cozy

canopy. We have two somewhat large hinges on one side for keeping the canopy attached, and three

latches on the other side, one up front close to the instrument panel to help keep the front lip down,

one closer to the front seat back to help keep the middle from flexing up, and one towards the rear for,

well keeping the rear in place.

 

Rock's Thinking: Uli's FHC: I am guessing here, but Uli simply duplicated the latch system on both sides

of the canopy to keep things simple or close as possible to the original. I might be wrong here.

 

Rock's NEW Thinking: FHC : Do we really need three latches on both sides? Wouldn't two latches suffice?

Since the front hinges act like a latch in that they keep the front part of the canopy in place and could be

seen to do the work of the "standard Cozy" front latches. Then we/I would just need a latch close to the front

seatback and one towards the rear portion of the canopy?

 

My concern with "Rock's NEW Thinking FHC" is that the distance between the front hinges and the front

seatback latch is about four (4) feet. Is that too long of a distance for the canopy not to be restrained?

 

Do you guys think the canopy would flex/lift off to much in this area or is it stiff enough to maintain it's shape

in this area?

 

Any and all latching idea/advice/ridicule are appreciated.

 

Thanks

[steve]

Hello all, again,

 

The Front Hinged Canopy build continues. Now that I have a plan for the canopy seal,

I need to plan for the latches.

 

Rock's Thinking: Side Opening Canopy: I understand the need for three latches with the standard Cozy

canopy. We have two somewhat large hinges on one side for keeping the canopy attached, and three

latches on the other side, one up front close to the instrument panel to help keep the front lip down,

one closer to the front seat back to help keep the middle from flexing up, and one towards the rear for,

well keeping the rear in place.

 

Rock's Thinking: Uli's FHC: I am guessing here, but Uli simply duplicated the latch system on both sides

of the canopy to keep things simple or close as possible to the original. I might be wrong here.

 

Rock's NEW Thinking: FHC : Do we really need three latches on both sides? Wouldn't two latches suffice?

Since the front hinges act like a latch in that they keep the front part of the canopy in place and could be

seen to do the work of the "standard Cozy" front latches. Then we/I would just need a latch close to the front

seatback and one towards the rear portion of the canopy?

 

My concern with "Rock's NEW Thinking FHC" is that the distance between the front hinges and the front

seatback latch is about four (4) feet. Is that too long of a distance for the canopy not to be restrained?

 

Do you guys think the canopy would flex/lift off to much in this area or is it stiff enough to maintain it's shape

in this area?

 

Any and all latching idea/advice/ridicule are appreciated.

 

Thanks

i had made 4 plans j hooks two in front and two at the rear

the geometry of the close was a thing to see.

but many things had to be reworked and it would end-up being high maintaining

i started over from scratch 3 times and now have only two plans type j hooks and it works good.

[Jack Morrison]

I had an E Racer with a FHC. Had the j hooks with a pull down at the back of the canopy. Held the front and rear of the canopy secure but above 200 kts it would lift in the center. Added two center pull down latches and worked fine except it was just another procedure to do. I had a front cover seperate and put a large scratch in the canopy and took 5 inches off my new prop. Decided to use a Cozy 4 canopy to replace the narrower E racer canopy. What I did was when I was setting the new canopy in place, I put a 1/4 inch block on the longeron on both sides at the rear most position, pulled the center pull down latches as installed. This bowed the glass frame slightly down in the center. After glassing the lens to the frame and let cure the canopy lens and frame had a slightly center down bow to it. After this was complete and flying, I no longer needed the center latches, have never lifted after that no matter what the speed or OT.

Just my 2Cts

 

Jack

E Racer Extreme

[Cozy1200]

Jack,

 

It's sad to here you write about your plane in the past tense.

[rnbraud]

i had made 4 plans j hooks two in front and two at the rear

the geometry of the close was a thing to see.

but many things had to be reworked and it would end-up being high maintaining

i started over from scratch 3 times and now have only two plans type j hooks and it works good.

Hello Steve,

 

If I recall correctly, you have your FCH with only the front most plexi lifting up at the shoulder/seatback location.

 

Just curious, about where did you locate the two j-hook latches?

[rnbraud]

I had an E Racer with a FHC. Had the j hooks with a pull down at the back of the canopy. Held the front and rear of the canopy secure but above 200 kts it would lift in the center. Added two center pull down latches and worked fine except it was just another procedure to do. I had a front cover seperate and put a large scratch in the canopy and took 5 inches off my new prop. Decided to use a Cozy 4 canopy to replace the narrower E racer canopy. What I did was when I was setting the new canopy in place, I put a 1/4 inch block on the longeron on both sides at the rear most position, pulled the center pull down latches as installed. This bowed the glass frame slightly down in the center. After glassing the lens to the frame and let cure the canopy lens and frame had a slightly center down bow to it. After this was complete and flying, I no longer needed the center latches, have never lifted after that no matter what the speed or OT.

Just my 2Cts

 

Jack

E Racer Extreme

Hello Jack,

 

Thanks for the response and sorry to hear bout your plane. Glad your ok.

 

My FHC is a little different in that is full-size just like the standard Cozy canopy, therefore, probably a little longer than yours. But I like your idea of building in a bow for the canopy. If I were to do this and since mine is so long I would probably replace the "center" latch with a pin cause the center binding when latching would probably cause the canopy to spread outward.

 

One of the options I am considering is a normal j-latch near the seatback, a horizontal pin at the rear which goes into the fixed turtleback, ala 80's camaro T-Top, and possibly a vertical pin in the center between the instrument panel and the seatback.

 

It will be a while before I install the latches, but I want to make sure I have the pads in the right places while building the canopy frame now.

 

Thanks again for the advice and good luck on your next build!

[steve]

Hello Steve,

 

If I recall correctly, you have your FCH with only the front most plexi lifting up at the shoulder/seatback location.

 

Just curious, about where did you locate the two j-hook latches?

1" forward of seat back on longerons

trick was with the right side you need to run a bar in the seat and behind the seat over to the left side (see the way the girls did theres).

i had the push car stile and loved them but one time it came open so i figured there would be flex at times and the dumb things mite let go, so in the trash that system went .