To S-Glass or not to S-Glass, that is the question

[rnbraud]

Ok, I have run this around my head enough times to make me dizzy.

 

I am hoping to receive my Canopy plexiglass later this week or early next.

 

I am doing a Front-Hinged Canopy ala Uli Walter's plans.

 

Now, my gut feeling, not scientific nor engineerific, is that a FHC would benefit from a stiffer structure.

 

Of course, the compromise is additional plys adding weight vs stiffness gained.

 

However, we have this wonderful product called S-Glass!

 

I have poured over the archives and other websites and understand the intricacies of fiberglass design/selection.

 

So, I am curious, if conventional wisdom.

 

Is there any benefit to using S-Glass BID and UNI in place of the usual E-Glass BID and UNI?

 

The S-Glass I would possibly use the the BID and UNI available from AS&S and Wicks.

 

Sufficient plys would be used to match the oz/sq yd specs of the usual E-glass.

 

Any and all comments, advice, banishment, encouragement, are welcome.

 

Later.

[brainfart]

I might be totally wrong here, but if you want more stiffness, why not carbon fiber?

[steve]

Ok, I have run this around my head enough times to make me dizzy.

 

I am hoping to receive my Canopy plexiglass later this week or early next.

 

I am doing a Front-Hinged Canopy ala Uli Walter's plans.

 

Now, my gut feeling, not scientific nor engineerific, is that a FHC would benefit from a stiffer structure.

 

Of course, the compromise is additional plys adding weight vs stiffness gained.

 

However, we have this wonderful product called S-Glass!

 

I have poured over the archives and other websites and understand the intricacies of fiberglass design/selection.

 

So, I am curious, if conventional wisdom.

 

Is there any benefit to using S-Glass BID and UNI in place of the usual E-Glass BID and UNI?

 

The S-Glass I would possibly use the the BID and UNI available from AS&S and Wicks.

 

Sufficient plys would be used to match the oz/sq yd specs of the usual E-glass.

 

Any and all comments, advice, banishment, encouragement, are welcome.

 

Later.

i have done the FHC and fixed the issue of rim movement.

the trick is .....don't fix it.

i will elaborate, as the canopy gets cold it gets smaller and there for lifts up on the forward most corners. if there is a hinge at this spot the canopy will still get smaller and will still pull up but not where the hinges are, but evey where else will lift, but in my 30 deg test all i found was the gap at the rear was wider, and that's a good thing. so IMO, if you keep the front stock and do the fhc you'll be in good shape.

[Lynn Erickson]

I might be totally wrong here, but if you want more stiffness, why not carbon fiber?

I used all carbon on my forward hinge canopy frame and have never seen any change in the fit from temperature

[Neverquit]

Hey Stevo! Your cat have an enima on the side of your plane?

 

 

Looks like we're still at the same stage. Strakes look great! Looks like my storage door in the nose.

[rnbraud]

Thanks all for your info.

 

I didn't consider making the canopy all out of CF. Hmmmm.

 

Will probably just stay with Uli's intructions for simplicity.

[brainfart]

Carbon fiber has a weird property: it will not expand when it heats up. Actually its expansion coefficient is not quite zero, it's even slightly negative, so it will contract slightly when the temperature rises. But for all practical purposes you can consider the coefficient of expansion to be zero.

[Jon Matcho]

So... isn't there a problem because the rest is fiberglass? What happens to the canopy in the summer and then in the winter? One of these materials is going to shrink/expand more than desired, no? Won't these cycles eventually break lose any water-tight seals between the canopy and its fiberglass frame? What's the secret to simple and robust here?

[brainfart]

> So... isn't there a problem because the rest is fiberglass?

 

I don't think so. The problem is usually not the little change in size directly caused by the expanding or contracting material, these changes are pretty small and the tolerances big enough. We are talking about fractions of a millimeter here. The problem is when you have laminates made from different components which cause a bi-metallic strip like bending of the laminate, this can cause pretty big distortions.

Imagine for example a sandwich with carbon fiber on one side, then some foam or honeycomb and glass on the other side. It might be perfectly flat at a certain temperature, but when you heat it up or cool it down it will bend considerably, especially if the part is large. If both sides are made from the same material or material combination and have the same number of plies it will remain flat.

 

Sorry, since English is obviously not my native language this is a bit hard to explain, I hope it made sense.

[ZUCZZ]

Mine pulls out of kilter enough without using any fancy materials

[Edge 513]

Uli's canopy surround lay-up schedule for both the inside and the outside is:

from the foam out- 2 BID 'glass + 2 CF BID + 2 UNI lengthwise. Ted built his to this schedule and thinks its the cats pajamas. My take is if you are going to lift that whole long canopy from the very tip on one end- you better use a schedule like that. Now what his does at altitude is a future thing-

I dropped a ply if the CF BID since I am only opening the front end and I ran the UNI sideways in front of the canopy, due to past bowing in the center as had been reported. Mine feels as sturdy as the Bismark... I also used 10 layers of CF UNI on the aft front hoop of the canopy [for a stiff Cee shape] and will have two on top forming the lipp overhang onto the rear canopy[not shown in pic below]. This UNI hoop work is similar to Lynns, and I thank him for it.