RV-9A, SoCal

[Jimbot]

Hi Doug,

Wow, everything looks great! And you made the VAF front page!

[rightrudder]

Thanks, Jim! The past few work sessions have been remarkably free of snags and mutilated parts requiring midnight internet orders to Van's. But there's always tomorrow...

Severe thunderstorm warning for tonight. Cool!!

[rightrudder]

Welp, I decided to tackle the fresh air inlets so I can rivet on the top skin, so I can final-attach the cowling mounts, so the cowling halves will line up precisely to finish off the piano hinge down the longitudinal split....you get the picture. It seems sometimes like half the energy expended goes toward thinking through the sequence of assembly.

I glued the inlets in place with ProSeal. I had worries that they might shift a bit as the goop sets up, but they're light and they stick in place pretty well. I secured them mostly from the outside with blue tape.

Another VAFer wanted to see a shot of the heat muff installed, so here's a pic, along with one of the airbox. Detail shot is of the stainless block-off plate for the carb heat outlet. I put a fillet of J-B Weld on the inside just for good measure.

[rightrudder]

Before cinching down the top forward skin, I had to drill holes in the diagonal brace for the roll hoop, so I decided to mount the roll hoop as well. It was a little too wide to get the 7/32" clearance on both sides, so I MacGuyver'd a press out of my workbench, a scissors jack and some spare lumber. I tried bending it first with my full body weight (200 lb.) and while it deflected noticeably, its springback dimension hadn't changed by a mm.

Got the little clamp widgets done. They're made of a very burly alloy...it took twice the pressure and twice the time on the bandsaw to make the angle cuts, but the strength is needed here.

Wore out two Unibits making the attach plates for the lower cowl, but it's final mounted with all the Skybolt fasteners set a half-turn deeper than flush. May have to adjust after paint, and settling from vibration. I really didn't need the floater receptacles, but I didn't have enough of the standard ones. Clearances of exhaust, alternator, etc. are all good. Though it's no substitute for removing the lower cowling, I was very pleased with how much of the induction system, fuel fittings and linkages you can inspect with only the upper cowling removed.

I was going to start riveting the top skin, but I thought it better to mull things over for another day to make sure I haven't missed anything. But to make the inevitable "panel dive" a little more comfortable, I ordered carpeting a couple of days ago. No accidental back surgery via floor stiffeners for me!

[JonJay]

Nice work.

[rightrudder]

Thanks, JonJay! Every day is a new adventure.

The cowling is now fully trimmed and mounted, with piano hinges along the sides. I just need to sand where the cowling butts up against the fuselage in a couple places where there's not enough gap for paint.

I'm super pleased with the size and uniformity of the side gaps, but the nostrils need a bit of work. I cut a little too much off the lower cowling here, but the upper cowling is straight and will be the reference.

With the cowling laced up but off the plane, I taped some waxed aluminum sheet to the upper cowling and applied flox, mixed to roughly an oatmeal consistency. When dry, it creates a perfect slim gap. Then I buzzed it down with a little sanding disc on my die grinder and smoothed it out. I may grind down the inner edge later and back it with some 'glass for strength, although the flox seems pretty stout!

Now for the access plugs for the piano hinges. (Many thanks here to BruceH and the pictures on his website that illustrate the process well.) After cutting out a ton of different shapes on paper templates, I decided on sort of a shield shape...the dimensions just work out to be aesthetically pleasing and have enough height for the nut plates. After taping up the cowling's newly sanded cheek contours and covering with waxed packing tape, I laid up four layers of 9 oz. cloth to make a blank for the "shield" plugs. Originally, I wanted to make them out of aluminum, but I found that I lacked the skills to properly bend them to the curvature. A man's gotta know his limitations... If I really want the aluminum look, I might apply some aluminum foil tape later.

[rightrudder]

I'm in the dreaded "waiting for epoxy to cure" mode. As a picture is worth a thousand words (and better written ), here are a few more.

[rightrudder]

Finished up the covers and installed #6 plate nuts and screws. They're a tight fit, so some edge sanding is in order to create a paint gap.

A bit more to do on the cowling, but I am SO sick of fiberglass that I need to shift gears and create aluminum dust. Bring on the baffling!!

[rightrudder]

The baffling is coming together nicely, after a Diet Pepsi-fueled marathon of deburring. There are a LOT of pieces here, and I'm glad that all the edges are smoothed out now. So much nicer to work with metal that doesn't slice one's hands.

I had the usual clearance issues with the oiler cooler. I wanted to have it far enough inboard that all rows of fins had a shot of cooling air, yet far enough outboard to avoid cooler/engine mount contact. After scalloping the inboard flange, I've got about 1/2" clearance. I wish I had a little more, but it should be OK.

When all the baffle seals are in place, is it really difficult to remove the lower cowling? The instructions show the inlet ramps pretty much flush with the fiberglass inlet edges in profile. Is everyone leaving a gap here of 1/8" or 1/4"? When the lower cowling is in place, do you have to grab the sealing material with needle nose pliers or something to pull it through the gap to get it above the ramps? Or do the ramps flex a bit downward to aid in the process? I've been trying to visualize this and it's really bugging me. I'd appreciate any insight here.

[bruceh]

You can cut back the baffles and leave about 1/4" from the fiberglass of the inlets. There is going to be some rubber baffle seal in there to fill the gap. This is a place where tighter gaps are not beneficial. My lower cowling goes on and off pretty easy and no issues with sealing and cooling.

If you get a chance to come out to the Ramona Fly In this Saturday you can get some up close looks.