SportAir Workshop

[Bcone1381]

Any one going to Oshkosh next weekend (Jan 27-28) to attend an EAA SportAir Workshop?

EAA hosts a series of SportAir Workshops every January in Oshkosh. This will be my third year attending. I come home energized after attending this event every year. In 2016 I learned Gas Welding, and felt very comfortable outfitting my shop with a welding set up after I got home. I am still a novice, but having the torch available has been pivotal at doing little simple things even with the kit.

In 2017 I attended the Sheet Metal Basics and feel very comfortable with the metal working the kit requires.

This year I will learn about electrical stuff. Within a week of arriving home from the workshop I hope to start building the foundation of my electrical system.

I will plan to wear my blue Bearhawk T-Shirt and Patrol Hat on Saturday. If you are a Bearhawk Builder and are attending look me up. Its not too late to sign up.

[Chris In Milwaukee]

I’ll be there for composites. See you there!

[Chris In Milwaukee]

Brooks and I are here at Oshkosh, he with electrical systems and myself with composites. If there are any groundbreaking developments, we’ll let you know!

[Bdflies]

Waiting with bated breath!

Bill

[Bcone1381]

I learned tons in the Electronic class today. I had never soldered, or installed a terminal end on a wire before. By the end of class I had success crimping PIDG ring terminal ends and splices on 18GA wire, wired a molex connector, and made a D-SUB connector assembly with a headphone jack and mic jack that we tested on a class room intercom system. When My D-SUB connector/headphone set up was tested, it did not work. We trouble shot it, desoldered some of my connections, still no joy. It turned out that the part Headphone Jack supplied with the kit (new from Spruce) was shorted out. It was very educational to see the trouble shooting that took place and came away with some extra knowledge and skills.

Two Lurkers on this sight found me in my Blue Bearhawk shirt this morning and introduced themselves. Luke and I met last year in the Metal Working class and took ...I think ...fabric covering this year. Luke also flies a PA-18-90, and a Trip Pacer. Austin was here for the first time and he took ....I think....Sheet Metal. We wondered this morning how many Lurkers are out there.

[Chris In Milwaukee]

So you were the troublemaker that Dick Kohler talked about! 😊

Sorry I didn’t stop by earlier. I didn’t know Luke and Austin were with you. Luke said hi to me in passing. Sorry, Luke and Austin! We’ll do it again next year, if not sooner!

In the composites class yesterday, we learned the basic theory of it all, as well as the benefits and drawbacks of certain materials, including carbo fiber and Kevlar. We worked with glass in practice. We built up a core sheet product by using a layer of glass, a layer of foam, and another layer of glass with a peel ply, and vacuum bagged it. First experience with vacuum bagging. It very cool. We also started on our Rutan-style wing cross-section layups with hot wire foam cutting, micro bead slurry to fill the material, and glass on top with peel coat. We did not use unidirectional material for the spar caps as you may have seen it done in the past. Lastly, we built up our own own wing root fairings using a strut mockup, some modeling clay, and glass cut on the bias. If you’ve ever done fabric covering, then think of it like a bias tape, where it will bend around corners and complex curves easily.

Today we’ll be taking our first parts out of the oven from overnight (120* hotbox) to see how they turned out. And we’ll be building other parts out of the sandwich we built yesterday. We’ll be doing a bunch of different techniques on this one piece like T-joints, filleting, strengthening an area for hard points, and a patch from damage, I believe.

For the uninitiated, a peel coat is a piece of Dacron (same stuff we use to cover our airplanes) as a top coat to the surface. It gets squeegeed in just as if it were a layer of glass. Excess resin wicks up into the fibers of the fabric. When it dries, you peel it off (more like rip it off like a bandaid), and the excess dried resin comes off with it, and leaves a smooth but textured surface perfect for priming or for another layer of glass, if that’s what’s required.

I can see everything that I’ve learned so far here being 100% applicable to building any composite part on a Bearhawk. Great fun so far, and still a day to go!

Oh, and the backdrop ain’t too shabby, either.

[svyolo]

Interesting. I have done lots of glass work. I have heard of "peel" coat, but didn't know what it was.
Composites have their place, and I am very comfortable working with them. But I would rather ride in a aluminum or 4130 primary structure as a homebuilt, and use composites to lower the weight of non structural parts. I have heard some of the earlier composite airplanes (Rutan, Glasair, Lancair) don't do a good job of absorbing energy of minor accidents, resulting in a bad outcome for the occupants. That was a politically correct way of describing the outcome for the occupants.

[Chris In Milwaukee]

That’s what I’m here for, the non-structural stuff. Today, while we finished up our wing cross section mockups, we also practiced sandwich materials (good for the other floorboard thread), glass joining and filling techniques, and most importantly for us Bearhawk folks, fairings.

Here’s a family photo of what we completed this weekend.



And a peel ply example:

[svyolo]

Was the strut fairing vacuum bagged?

[svyolo]

For flat panels (floorboards, interior panels, main gear fairings) I will just make flat panels by laminating onto a sheet of glass. Then peel the sheet off. Instant flat female mold. For sandwich panels, I will add the core onto the first panel while the epoxy is wet, and then that to the second ply when it is wet. Probably 1 sheet a day. 10 - 15 minutes.

[Chris In Milwaukee]

Was the strut fairing vacuum bagged?

The strut fairing was not vacuum bagged. It is a hand layout with two layers of cloth cut on the bias. We used modeling clay to make the fillet shape around the strut, and then laid up the glass against it.

Here it is coming off the mold:

[Chris In Milwaukee]

For flat panels (floorboards, interior panels, main gear fairings) I will just make flat panels by laminating onto a sheet of glass. Then peel the sheet off. Instant flat female mold. For sandwich panels, I will add the core onto the first panel while the epoxy is wet, and then that to the second ply when it is wet. Probably 1 sheet a day. 10 - 15 minutes.

That’s pretty much the technique used here. Sheet of aluminum was waxed so it would stick. Wet layup of one glass layer on one side of the core. Flipped it over and laid it on the waxed aluminum. Wet layup on the other side. Layer of peel ply, after that. The only addition was this piece was vacuum bagged. That T~shaped project was made from it.

Wish I had thought to take a picture of the bagging process. It’s pretty cool.

[rodsmith]

Must be great to live close enough to Oshkosh to participate in multiple workshops. Except for welding I have self taught all the other building skills with all the learning mistakes that go with the trial and error process. I took junior college classes in gas and TIG welding that really helped. I really owe my TIG welding skills to a co-worker who was a real master at it and great teacher.

[Chris In Milwaukee]

Must be great to live close enough to Oshkosh to participate in multiple workshops..

I’m certainly a lucky guy!

[Bcone1381]

Chris;

How costly are the "tools and consumables" for vacuum bagging? Things like the bag, the pump, and I don't know what else.

[Chris In Milwaukee]

Chris;

How costly are the "tools and consumables" for vacuum bagging? Things like the bag, the pump, and I don't know what else.

I have a vendor list in my workbook. I’ll work up what I think would be a pretty average cost. The pump, from what I understand, can run from about $160-500 depending on brand. I don’t have a handle yet on some of the stretchy plastics.