Thorp Air Command - T18.net

So I will post pics but have been working behind the scenes here. Got my new tank built (aluminum) New tank skin, with gas door, drilled and dimpled. The new stainless firewall was bucked last weekend with my sons help. New roll bar drilled and ready for bolts. And new windshield installed. Stripped the paint from the entire fuselage and stripped bare. My canopy is in surprisingly good shape, I dont know the age but suspect several decades. BUT I can not live with the frame. So I dont even have a new set of plans for it. Not that I need it, but obviously am not building the original with the bar overhead down the center. But I really do have a question here for the gang. I see on the plans (as on the old canopy frame) call out for 3/4 OD .035 6061, and then you use the 8-32 nutserts to hold the canopy on. (and heres the question) Has anyone used say .049 or .065 and just taped the frame instead of using nutserts like the windshield??? How much heavier could it be? The way the old one felt never gave me great confidence moving back and forth. Well there it is let the mayhem begin.

My late best friend, Dean Cochran, used heavier tubing for his canopy frame, as did I. I used rivnuts and he just tapped the holes. Either way seems to have been fine... 25 years for me, and probably 35 for Dean's T-18. Sorry that I don't recall the exact wall thickness, but .049" I think.

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John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

Maybe not so dumb question, has anybody used nutserts into the actual windshield? I had some left over material and was playing around with it and have had no issues. Could it be that after time you would get a crack? Reason is the clearance between the fairing screw going through the windshield and then into the dash deck. If I could use nutsert into windshield would have all kinds of room. Cant believe I am the first to ask this. So what do ya think?

Expansion , expansion , expansion ! You need a side space between what ever goes thru the plexiglass . Also I believe you will create a stress on the glass with the nutsert as it expands in the hole and with variations in temperature sooner or later the glass will "crack" IMHO . The thermo dynamic engineers can weigh in on this . I am just a small town pizza lawyer .

RB

According to Jeff Rogers, Airplane Plastic, metal expands with heat and plex expands with moisture. The result is mass movement and wiggle between the two. The RV crowd pop rivets the plex to the frame with varying results. I made some backing strips with nutplates to catch the screws coming through the boot cowl and windshield. The windshield itself is drilled to about 1/2" and floats on rubber strips glued to the boot cowl and the nutplate strip. Seems to work.

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Bob Highley
N711SH
SN 835
KLAL

Don't install nutserts or rivnuts directly into the acrylic windshield, for all the reasons stated and several others. Good advice.

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John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

One other option is to not use screws at all. I bonded my windshield and canopy to the frames using Sikaflex. The only holes in the plexiglas were about four #40 holes for clecos to hold in in position while the material cured. I think there are photos and an article somewhere in the old newsletter archives.
GG

Sika seems to be a popular alternative over on the RV site too.

To hell with the nuts ! I stole this idea from Dan . Only four screws on each side of the fus. to hold the glass . The "clips" did a great job and along with the EPDM WX strip no leaks ! In addition no need for the external trim strip on the lower edge of the wind screen .

RB