Windscreen Fairing 4" from Windshield

Question for the brain trust:

Why do we sand and etch 4" from the base of the windshield on the F-1071 forward fuselage top skin?

The final layup calls for a 3.5" wide piece which covers about 2" or so on the top skin and 1.5" or so on the windshield using the 7" radius piece.

What am I missing and what covers that area?

Thanks
Ethan

ethand said:

Question for the brain trust:

Why do we sand and etch 4" from the base of the windshield on the F-1071 forward fuselage top skin?

The final layup calls for a 3.5" wide piece which covers about 2" or so on the top skin and 1.5" or so on the windshield using the 7" radius piece.

What am I missing and what covers that area?

Thanks
Ethan

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You're going to have filler (micro, for instance) to apply and sand on top of the fiberglass and the area where it transitions to the skin. 4" gives you plenty of margin to fair in the transition.

No plan is perfect

When I have tried to do something to a perfect plan it always goes beyond the prepared area. Having even 1/4" of unprepared surface can create a separation that could allow ice and water and progress to the prepared area. Wouldn't you just hate to find a crack there later?

Truly in the YMMV category.

Consider it extra runway.

it is overkill...

Sand out a couple of inches to where you are doing the glass work...tape so some of the sanded area is covered, 1/4".... let the guys/gals doing the real and final finish sand out further.. that's my suggestion. If you are the final finish guy go for it, but most paint shops DO NOT want builders trying to do the final finish out on fairings etc....it is a waste of your time and they will likely do it much better than you (or at least me!)

WrightsRV7 said:

....most paint shops DO NOT want builders trying to do the final finish out on fairings etc....it is a waste of your time and they will likely do it much better than you

Click to expand...

Fat chance of that. I recommend that you never depend on a paint shop to finish your fiberglass. I've seen too many high-priced paint jobs over rough edges and wavy surfaces, and most of the time the owner has no idea what they put under the new paint to get it finished quick.

Speaking of final finish... I've been elbows deep in fiberglass for seemly forever with the cabin top and doors. Yesterday I did some rough sanding on the fairings and then used some fairly thick micro, tin foil and my 7" radius sanding block and pushed the micro into a rough shape (FYI Tinfoil will stick to fiberglass, at least the shiny side).

Went out this morning and using the actual sanding block spent a good hour working it down into a shape, as well as pulling off bits of tin foil... Then I mixed up some semi wet micro and using a bondo spreader worked it over to fill any pits.

I guess my question is giving the strange shape as it transitions from the radius to the sides is it okay to hand sand this with some 180? Or should I try to block it out and hand sculpt it were I can? Sorry for the thread hijack...

I'm maybe a week behind you

but my guess is that the pro advice you're about to get is not to hand sand anything you can possibly get to with other means: sandpaper over a tube, flexible block, etc.

Fingertips pressing into sandpaper is a no-no except in small, fingertip-sized nooks. At least that's what I've heard around here and believe to be true.

I've decided as of this morning to flatten the rounded convex radius of my door opening and bevel the door edges to match -pretty much per plans. I'd like to modify my hole finder to serve as an edge finder for this purpose: the protruding rivet is going to give a line too far inboard unless I drill a second, re-calibrated hole in the top strap for this purpose, but if successful I see this saving me lots of trim-and-fit iterations on the way to a final result.

Good luck, Justin. Post pics!

That makes sense. I have some flex sander blocks now so I'll work with that. It's the basic shape right now, just need some refinement and to smooth it out before I UV Prime it.

I haven't decided what I'm doing on the door opening bevel yet. Probably just as the factory has it, the 45 degree bit.