Skylight. Bearhawk hump and all.

[Wes Ragle]

Hi Guys,

I ordered the wrong engine mounts (vibration isolaters). I re-ordered but the correct ones haven’t come in yet so I had to find something else to work on this weekend.

I have been fretting for a long time over how to do the skylight. I have looked for, but not found, a skylight plan that accommodated the “Bearhawk hump”.

Since I have never welded anything, and really don’t want to learn on a Bearhawk quick build fuse, I decided that this weekend I would take my best shot at fabricating a skylight that doesn't require removal of the hump.

Here is what I came up with. Maybe not the best, but I have to get moving or I’ll never get finished. First I built a former (or whatever you call it) around the rear spar carry through.

1. I vacuum formed a piece of 025 around a piece of tubing the size of the rear spar carry through.
2. Captured the rear spar carry through with three pieces of square aluminum tubing.
3. Used more square aluminum tubing to make the top of the former.
4. Made angle brackets to support the former from the rear.
5. Applied fasteners as necessary to mate the brackets and provide attachment points for the Lexan along the top of the former.
6. Capped the former. I left some material extending aft past the top of the former to attach the rear fairing to down the line.

The stringers were beefed up in the front by shaping a piece of aluminum bar, tapping it into the end of the stringer, and riveting it in place. Then a #3 bolt was used to attach it to the forward most stringer saddle.

Flanges were applied to the stringers to secure the Lexan. Clips were used on the tubing forward of the last saddle.

Three pieces of Lexan were fitted and faring strips added to the top. The top strips were edge rolled so they would lay down nicely.

I still need to trim, drill holes to final size, and add forward and aft fairings. Hopefully get that done this week in the evenings.

Not very efficient due to the number of parts that had/have to be made, but all and all I think it is a workable solution.

Happy Building,
Wes

[Battson]

Nice work! There has clearly been a lot of thought go into that.

[Wes Ragle]

Thanks Jonathan.

If I had it to do over I would probably add two rows of rivets in the cap and *not* have the cap wrap around to the front of the former. That would make for a more finished look.

BTW, I thought I already replied. So, if another reply shows up, it was lost somewhere in the ether.

Wes

[alaskabearhawk]

Make sure you have clearance between your trim cable and the aileron cable that passes through the cabin. (ref photo 20039)

[Battson]

The parts affecting those clearances are all pre-made in the QB kitset, so I would be surprised if there was a problem.
It looks like Wes hasn't modified any of those parts.

[Wes Ragle]

Thanks for the heads up Paul.

I haven't thought that far ahead.

I did hook up the trim cable (added pic to original post) and it passes pretty much right down the center of the hole in the former. So, if I have a problem now I had a problem to start with ;-)

We'll see,

Wes

[John Bickham]

Thanks too much for sharing. I'm going to use some of those techniques. Any pics of your windshield/skylight interface techniques?? I'm still working on how I want to do that.

[Wes Ragle]

Hi John,

You're welcome :-)

The front edge of the lexan will be secured by a fairing and three #8 screws in each section. The spacing of the screws is such that a screw falls right by each of the fairing strips that run along the seams (to help seal things) . The screws are as far aft as practical on the windshield channel.

Once the windshield is fitted, if I need to, I will reach through the screw holes and prick the windshield with a plexi bit. Then I will do whatever it takes to "big time" clearance the windshield from the screws.

I'll add a couple of pics when I come in from the shop later.

Later ...

OK, added three pics to the original post showing the forward fairing. It is just a strip of 025 with a small bend and a "fold" which tucks slightly back into the windshield channel. One of the pics shows some of the attachment holes from the inside.

This evening was spent trimming the lexan to final size and adding attachment holes along the outside and rear edges. I'll work on the rear fairing tomorrow.

Wes

[Wes Ragle]

​Hi Guys,

Just in from the shop. I made the rear fairing. Attached are four pics which show approximately what the finished product is like from the inside, the front fairing, and the rear fairing.

I added one more that shows that where former cap extends aft past the top of the former and the aft fairing meet there is a gap at the trailing edge but the pic doesn't show it very well. Both pieces are "falling away" from the future fabric at the trailing edge.

I will have someone who has experience with fabric have a look at the setup at the rear before I commit and add nutplates to secure the trailing edge of the fairing to the former cap.

That's about it for the skylight. I'll drill the holes along the windshield channel to final size while fitting the windshield. I'll trim the rear fairing when I fit the wing root fairing. All holes in the fairings will be dimpled. The holes in the lexan will be counter sunk (deeper than normal) and drilled oversize to allow for thermal expansion of the lexan. When the screws are finally put in, they will have elastic stop nuts and will be just snugged, not too tight, again to allow the lexan to move a little.

Oh yea, I almost forgot. This design has obviously not been tested. I think it will work, but it may flutter and fly off during high speed taxi.

On to what's next.

Wes

[Brad Ripp]

Wes,
I am doing mine similar and have a couple questions. Did you buy the u shaped brackets that attach to the bottom of the tubing run or did you make those? I'm planning to use one solid sheet of Lexan instead of 3 panels. I tested and it seems to contour well. Do you think I need a strip of aluminum both above and below the Lexan with the u bracket on the bottom, or just the u bracket on the bottom and one strip of aluminum to cap it off? I may also weld tabs to the tubing to bolt to instead, but it seems like less work to use the u brackets. Do you get any added vibration using the U brackets? Any recommendations in hind sight? Thanks, Brad

[Wes Ragle]

Hi Brad,

Sorry for the late reply. My son got a job offer in Battle Mountain NV. I live in north Texas. He asked Millie and I to help him move. 3000 miles later we are back home.

Yea, I made the "u shaped brackets". Made them 063 thick. Just found a drill ~0.126' larger in diameter than the round stock it captured and drilled and shaped a hole in bar stock. Then found a bit the same diameter as the round stock and pressed the "clips" in a vice.

I don't think you will need the the bottom strip of aluminum if you are able to make a single sheet of lexan work. I used the bottom strip to stabilize the splice.

I could not make a single sheet work with the bearhawk hump. I did buy a thin sheet at the Home Depot and clamped/wiggled it around until I was blue in the face. Would always end up with "slack" along the rear edge.

Sadly, I have not flown the plane yet ;-( Hopefully before too long.

Best of Luck,

Wes

[Sebastian]

I didn't have the pictures I wanted to show you of what I did with my skylights IMG_1890.JPGIMG_1891.JPGIMG_1889.JPGbut here they are. I also didn't take the hump out. IMG_1888.JPG