Todd's canopy

[samiam]

Anyone have any experience with a Todd's canopy in the sonex? I haven't been able to find much, but a couple people have said that there is less side-to-side headroom than the standard canopy. I'm not sure how that could be - it looks to be much roomier overall. His customers seem very pleased. Anyone have one on their sonex and care to report?

[vigilant104]

One point: The standard canopy and windscreen uses a Lexan (flat-wrapped) windscreen and an acrylic canopy. The Todd's canopy and windscreen is all acrylic. Because it is "blown" all at once and then cut, the Todd's canopy generally has a nice, continuous "line" when viewed in profile. This is hard (but not impossible) to achieve using the standard construction method.
There's a significant difference in impact tolerance between acrylic and Lexan (polycarbonate). They are both clear and they both look about the same, but they behave very differently when hit. If a bird should ever become very big in your windscreen, this could be important.
-- This thread on the Homebuilt Airplane board gives a great description of how one RV-8 builder modified the "stock" blown acrylic windscreen with a flat-wrapped polycarbonate windscreen. (Subsequent edit: Charlie Radford correctly points out that the RV-8 builder used plexiglas, not Lexan for his new windshield. True, I missed that.) http://www.homebuiltairplanes.com/forums/aircraft-design-aerodynamics-new-technology/11740-rv-8-windshield-mod-2.html. He did this after several birds entered his cockpit and nearly blinded him after coming through the acrylic windscreen. Three quail at about 165 knots--in fairness, that's a lot faster than most of us go. Good photos at the above link of the hole left by the birds.

There are some fairly well-done videos on the web comparing the impact resistance of acrylic to Lexan. Lexan "gives" a lot more, whereas at the same stress levels acrylic will crack/fracture. Here's a video of acrylic and Lexan motorcyle windscreens being subjected to some impacts. It's not scientific, but it is an attention-getter. http://www.youtube.com/watch?feature=player_embedded&v=HlEfJFDWXpM

Many people really like their Todd's canopies and have been flying with them successfully for years. I'm satisfied with my "stock" windscreen and canopy.

[MichaelFarley56]

I agree with Mark 100%. I've had several close calls with large birds and even though I haven't hit one (yet), I like the increased safety factor of the Lexan.

Also, this is completly my own opinion, but I'm not in love with the "bubble" shape of Todd's canopy. I prefer the stock look with a (profile view) straight line from the cowling into the front windshield into the canopy, as opposed to the popped up windscreen.

That being said, there are a lot of people who are very happy with their Todd's Canopy. I know of several RV guys who have one and love it. I can't remember for certain but seem to recall that if you want a custom canopy with a specified shape, Todd's people can custom make you a canopy. Always nice to have that option!

Good luck!

[radfordc]

-- This thread on the Homebuilt Airplane board gives a great description of how one RV-8 builder modified the "stock" blown acrylic windscreen with a flat-wrapped polycarbonate windscreen.

In the article he said he used "plexi"...which I took to mean plexiglas. Plexiglas is also an acrylic sheet.
http://www.plexiglas.com/en/

[daleandee]

*

[vigilant104]

-- This thread on the Homebuilt Airplane board gives a great description of how one RV-8 builder modified the "stock" blown acrylic windscreen with a flat-wrapped polycarbonate windscreen.

In the article he said he used "plexi"...which I took to mean plexiglas. Plexiglas is also an acrylic sheet.
http://www.plexiglas.com/en/

Charlie,
Thanks, good catch. He used plexiglass (acrylic), but increased the thickness. I amended my earlier post.

One other advantage of the Lexan flat-wrap approach compared to an acrylic windshield-and-canopy: If you need a new windshield someday it can be done by itself without needing to replace the canopy, too. That's a consideration if a splash of fuel should ever find it's way from the oh-so-close filler and onto the windscreen. Of course, it's best to avoid that.

[radfordc]

Good point. I'm on my third windshield now. The downside of Lexan is that it scratches relatively easy...but it's cheap and fast to make a replacement.

[Sonex825]

I have todd's canopy and I absolutely love it. The clarity is impeccable and I have abused the hell out of it and not a single crack yet. I cut the canopy to size with an angle grinder with a blade made for cutting plastics. I would highly recommend it. As far as the bird strikes I call BS on that! I have bent a scrap piece in near half trying to break it to put in the trash and had a hard time. I think it comes down to what look you like better and whether you want to roll the dice on breaking a pricey item.

Eric M