Fun with flap actuators

I had only a little time tonight to spend in the shop, but managed to get a lot done.

First, I managed to improve the fit of the flap housing sides – this is the problem I mentioned in my last post.  These things are very thin aluminum and aren’t at all structural, so I enlarged some of the screw holes to allow the part to “float” a bit when all the fasteners are in place…seems to work fine.  Sorry, I didn’t take any pictures of them after reinstallation.

Flap motor temp fitSecond, and more importantly, I temporarily mounted the flap actuator to its housing. There’s one aluminum angle supporting the flap actuator that still needs to be mach-drilled to the forward brace – you can see the angle above and very slightly to the right of the actuator motor (for all you non-RVers, it’s the cylindrical thing with screws on the end).

Flap motor up closeHere’s a closeup of the angle.  One of the cool parts of this process is powering up the actuator with a battery to run out the actuator arm so it can be bolted to the flap arm.  The flap motor hasn’t been run in five years, but it worked fine.

With the whole angle/actuator/brace assembly in place, and with judicious application of a clamp to the angle, I’ll match-drill the angle and brace…but not tonight.  I’m whipped and it’s bedtime.

Collected works

It’s been a couple of weeks since I posted any progress on the fuselage.  Doesn’t mean I haven’t been working, I’ve just been too busy to update the website.  Here’s a quick collection of everything I’ve done recently.

Once I knew I could connect the fuel pump to the fuel selector, I positioned and drilled the forward tunnel cover to the center floor stiffeners.  The plans only call for two fasteners on each side, but I added another to accommodate some reinforcements for the fuel pump support structure (more on that below).

Forward tunnel cover drilled

The’s nothing particularly difficult about drilling these holes, except that the bottom surface of the cover needs to be 15/16″ above the floor.  Some spacers made from scrap 2″x4″ made that relatively easy.  I also used a bit of scrap 1/8″ aluminum angle as a drill jig to make sure the holes were drilled at the right height above the floor..big thanks to Mike Bullock for that idea.  And for me at least, angle drills are hard to position precisely…the drill jig helped with that as well.

Drilling the tunnel cover

Andair publishes a really nice set of plans for a reinforcement structure to support their fuel pump and filter on the forward tunnel.  Problem is, their heavy 1/8″ support angles completely block off area under the tunnel, and make it impossible to run wiring through that area – and they’re complete overkill structurally for a pump that barely weighs a pound.

Plans vs actualAfter doing some research online, I found other builders were using 0.63″ angle and plate to reinforce the pump mounting area.  And since Van’s mounting bracket for the Airflow Performance pump and filter is made from a similar gauge of aluminum, I decided to go with the reinforcement plate and angles.

Pump doubler

Here’s the plate and angles match-drilled to the bottom of the tunnel cover.  I’m very happy with the way this turned out.

Tunnel fitted

Knowing that the pump and filter were in a good location, and with the mounting holes drilled, I opened up a rectangular area ahead of the pump per Andair’s plans, to allow the fuel line to route under the tunnel cover to the firewall.

Pump housing drilledThe only thing left to do in this area was to match-drill the pump cover to the tunnel and fuel valve cover.  Nothing too difficult here, just need to make sure the pump cover flanges are positioned neatly along the tunnel sides.

Oil filter cutout nutplatesThere’s a portion of the tunnel cover that acts as a heater plenum, and it’s attached to the firewall oil filter cutout with #8 screws and platenuts.  I’d forgotten what a pain in the ass it is to drill stainless steel…the screw holes aren’t beautiful, but they’re functional.

The final bit of work to do in the forward fuse was mounting the flap actuator, motor and support structure.

Flap actuator arm mountedI haven’t touched this weldment and supports in a couple of years, when I match-drilled the UHMW supports to the seat back bulkhead.  One less part in the pile…

Flap motor safety wire drilled

Van’s issued a service bulletin several years ago requesting that builders safety-wire the flap motor rod end to make sure it doesn’t unscrew itself, thus making the flaps inoperative.  Per instructions, I drilled a hole for the safety wire.  I was afraid this would turn into an expensive mess, but the center punch and a #50 drill bit made quick work of it.  I know, the picture is fuzzy…sorry.

Julian in the fuseI had a special visitor during the flap marathon this weekend…my nephew Julian stayed with us for the day and came down to the shop.  He’s into trains right now, but we’re working hard to get him hooked on airplanes!

Forward flap housingI didn’t take many pictures while assembling the flap housing.  Here’s the forward, and most structural, flap housing brace where the flap motor attaches.  At the top I clamped into place a small, angled splice plate that’s about to be match-drilled to the seat back and brace.  At the bottom, I’ve already riveted two small angles that connect the brace with holes and nutplates on the floor.

Forward flap housing againThe seat floor tunnel cover will need a little tweaking to fit next to the forward brace…nothing that can’t be handled by judicious application of a mill file and scotchbrite pad.

Rear flap housingHere’s the back part of the flap housing.  Nothing too sexy here, just a c-channel and piece of angle match-drilled to the rear tunnel cover.  The top is match-drilled to the seat back.  The only slightly tricky part is centering the channel on the seat back; I measured the distance between the prepunched seat back holes, and used that measurement to lay out a couple of reference lines on the channel so they’d be visible through the seat back holes.

Flap housing w sidesHere’s everything all match-drilled and clecoed together.  The side panels are very thin and don’t snug down very well on the forward housing.  I’ll brain out a fix for that later.

Why we didn’t build a tandem RV

I brazenly stole this picture from an online humor site.  In all likelihood it was taken in Wales, in one of a series of deep valleys nicknamed the Mach Loop.  It’s frequently used by RAF and USAF crews practicing low, fast flying.  That, in turn, makes it popular with photographers equipped with telephoto lenses who perch on the valley sides waiting for opportunities like this.

Mach Loop

Obviously the WSO in this RAF Tornado anticipated the photographers…

Small victories

Small victories…gotta take ’em where I can. After a lot of head-scratching and experimentation, I managed to fabricate the fuel line that connects the selector valve and filter/pump assembly.

? line fabricatedI had a lot of help from fellow builder Bruce Swayze who shared a lot of information on how to bend this fuel line in just the right way. Thanks, Bruce!

Beseated

Our seats arrived today from Luke and the folks at Classic Aero Designs…they’re very nice, well worth the investment. My good friend Jim has the same seat model in his RV-7 and one ride in his airplane was enough to convince me that these are the ones we wanted.

Seats!

I’ve been holding my breath on the choice of interior colors, seat leather, and shoulder harnesses. We made our choices two years ago based on leather swatches from Classic Aero, harness material samples from Hooker, and paint chips from Sherwin Williams.  It all looked good in small scale, but there’s no way to tell until everything comes together in the cockpit.

Now that the seats are next to the walls and floor panels we’ve painted with JetFlex, I think we made the right choice…or to be more accurate, Ellen made the right choice.  She did all the color coordination and everything looks great!

Another picture? Sure, why not…

More seats!The only downside is that now we know the interior paint color is correct, I’ve got to buy more of it at $120/quart…yikes.

A lot of time spent and not a lot to show for it

Some days you spend a lot of time in the shop and don’t get much done…a lot of lateral or backward motion, without a lot of forward progress. The last few days were like that.

I mentioned in the last couple of posts that I needed to fabricate an aluminum line that connects the fuel selector to the fuel filter/pump.  Turns out that Van’s ships its RV-7 fuselage kits with 8 feet of 3/8″ diameter aluminum tubing for fabricating all the fuse fuel plumbing, and I used just about all of that trying – and failing – to make one simple damn 8-inch line.

A waste of tubing

You might think from the picture above that I got it just about right, but there’s just not enough space left at the top of the line to attach the same AN coupling that’s on the other end. So I did what any good civil servant does – I threw money at the problem. I ordered some right-angle AN fluid fittings from Aircraft Spruce that I hope will solve the problem. More to follow…

The next item on my punch list was fitting the forward fuel line covers. Before I could do that some clean-up work was necessary – mounting and torquing a couple of corner gussets that take the place of landing gear weldments for the RV-7A main gear.

Corner gussetSorry, this is a crappy pic but you get the idea. I’d actually finished these gussets several months ago, but the left one (pictured here) needed some work with a file to clear one of the skin-to-spar rivets. Once the gussets were in place, I moved on to mounting the forward tunnel covers.

The covers themselves are easy, but support angles on each cover’s outboard end require some sheet metal gymnastics to fit and drill to the heavy F-7101 gussets on each side of the fuse. Fortunately, I used a technique devised by fellow RV builder Mike Bullock, and it worked like a champ. I won’t steal Mike’s glory, so here are the highlights.

Clamped angle

Here’s a piece of scrap angle clamped in place through the fuel line access hole, to provide a fore/aft reference for the actual support angle. It’s adjusted so it’s flat against the cover.

Bracket clampedHere’s the support angle itself, already trimmed and pre-drilled according to plans, clamped to the scrap angle with a piece of 0.020″ scrap in between to simulate the forward cover.

With the support angles clamped in place, I match-drilled them to the F-7101 gussets with a #40 drill bit, which will eventually be upsized to #30.  I used a drill stop to avoid drilling through the outside skins.

Covers match-drilledHere are the covers match-drilled to the support angles; when they’re done the covers will be attached to the angles with #8 screws. All that’s left is to enlarge the holes to final size and debur everything. It took several hours to fit and drill these parts, but everything came out fine.

Thanks for the great instructions, Mike!