Extreme Windshield

Moderator: SheepdogRD

Extreme Windshield

Postby SheepdogRD » Tue Mar 12, 2019 3:00 pm

I figured that a longer, wider windshield would give us improved visibility, particularly over the nose on approach, and out the sides when taxiing and landing. If the windshield went all the way forward to the firewall, a flatter windshield angle might even have a positive aerodynamic effect.

So, about four years ago, I started trying to build a larger windshield. Early attempts just didn't work. I discovered that Lexan is wonderful stuff to work with, and it's pretty forgiving. But it wants to stay flat, so we have to engineer it to the shape we want. There were lots of starts and stops, and an unenviable string of attempts that ended in "Well, that didn't work." But each attempt got me closer.

Not long after I started the project, I met Barkley Smith of AeroSmith Composites. AeroSmith manufactures the fiberglass parts found on Just Aircraft. Barkley is both artist and craftsman, and he's fun to work with. If I toss out an idea, he tosses it back improved in some way. He wanted a bigger windshield, too, so we've worked on this together.

We've taken the windshield to the limits of the space available. Here’s the Extreme Windshield, installed on N570L:

01 Windshield in Place.jpg
Windshield in Place


02 Windshield from the Side.jpg
Windshield from the Side

This windshield provides better visibility overall and a more spacious feel to the cockpit. It extends from the headrack all the way forward to the firewall, and clear across the full width of the cockpit. It The new boot cowl is very short across the front, and the sides are only as high the tabs on the fuselage rails.

If you choose to minimize the height of your panel, or angle the panel sides down (Steve Henry did both on YeeHaw 7), or if you reduce the panel width, this windshield provides a great view out.

The panel on N570L is less than 19" wide; it leaves almost 7" open on each side, and I can see clear to the firewall on the opposite side of the cockpit just by turning my head. Smaller side gaps still provide much better vision out. With Lexan cowl side panels and a narrowed instrument panel, the view is amazing...

05 Windshield from the Pilot Seat.jpg
Windshield from the Pilot Seat

... and it will get better. The sides of the boot cowl in the picture are about 2-1/2" high. They'll be cut shorter -- to less than 2" -- when the installation is complete.

A much larger panel cover is required -- about 21" x 36". But the cover lines up well with the eye, so we'll be looking over it out the windshield, and under it out the side panels. The one on N570L will be .040" Kydex.

The windshield is .090” Lexan sheet that comes with the Just kit. The current system uses the 914-style cowling, meaning it should fit new installations of Rotax, Titan and Yamaha engines, and may fit other planes using the 914-style cowling. We’ll be trying other engine installations.

It may be possible to retrofit the windshield to some existing 914 cowling installations, but we haven’t done that yet. It might even be possible to retrofit 912 cowling installations, but we haven't tried that, either. We'll try.

Installing the Extreme windshield is different from installing the standard cowlings. The windshield and boot cowl are installed first, and then the upper and lower cowling pieces are installed to fit with the boot cowl.

The key to installing this windshield is a fiberglass former seen in the picture above and the one below (although the former appears to slant forward in the picture below, it's actually upright). The former, which is riveted to the firewall, makes it possible to bend the Lexan to the shape we need at the front corners. The installed windshield is sandwiched between the former and the boot cowl.

03 Windshield Former.jpg
Windshield Former

A Work in Progress
We haven't flown this yet, but test flights are on the way.

There's one issue we're still resolving -- fitting the upper cowling to the boot cowl. Here's the issue: various engine and prop spacer installations require different length cowlings. But the Just cowling system is tapered. It gets wider as it goes back from the nose. Measured 7 inches back, where the sides get relatively straight, it’s about 25” wide. At the back end, some 33” from the nose, it’s about 33” wide. The firewall is only 31-1/2” wide. That means there’s only one position where the cowling fits ideally, and any other position requires the builder to bend the cowling system to fit. The cowling can flex a little, so there is a range of acceptable nose lengths.

Most 912 installations on the bed mount use the "912" cowling because it fits better on shorter engine installations. The "914" cowling is the better choice for “ring” mount installations, where the engine is 3” further forward. The 914 cowling is the basis for development of most other cowlings -- Titan, ULPower, etc. We’ve also made it the basis for a new lower cowling that has an opening for the radiator, similar (in size, anyway) to the one in the 912 cowling. It should fit almost all 912 and 914 installations, including those that previously would have used the 912 cowling.

The Titan upper cowling has relatively straight sides because of the cowl cheeks, so it should work well. It looks like Steve's Yamaha installation is right about where my Rotax is, so it should fit without a lot of grunting, too; we’re in that “sweet spot” of cowling length. But other installations, such as 912 engines on the bed mount, are shorter, and that would make the existing 914 upper cowling too narrow because it sits further back.

We've designed a new upper cowling that fits this windshield no matter how long the engine/prop installation may be. It's ready to prototype; if it works as expected, it'll make installation a whole lot easier. To test, we'll install it on my 912 big bore on the "ring" mount, and on Barkley's 912 on the bed mount. I'll post on that when we have results.

There’s more to come...
Richard Holtz
Highlander N570L -- Ms. Tonka -- in gestation

If just enough is really good, then too much ought to be perfect.
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SheepdogRD
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Re: Extreme Windshield

Postby Clark in AZ » Tue Mar 12, 2019 4:22 pm

Very nice! Looks fantastic, I wish you well in your tests.

Clark
Building SuperSTOL Kit 512
Cave Creek, AZ
Clark in AZ
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