Saturday, January 10, 2009

Beginning installation of the VP-50 in an RV-7A

There is no documentation, as far as I know, of an install of the Vertical Power 50 in an RV-7A. The VP-50 is the low-end version of the solid-state electrical management system, that eliminates (for the most part) circuit breakers and fuses. This will be the brain of my electrical system and after weeks away from any substantial progress on the RV-7A, I figured it was time to get serious. So I've set up a VP-50 category for folks in the future who want to see how this system fits.

The heart of the system is the control unit, which essentially is the main electrical buss. It takes power from the battery and distributes it to my various electrical goodies. I'll install the battery in a few weeks.

I wasn't sure where to mount the control unit. The instructions recommend some aluminum angle brackets to be installed between the subpanel and the firewall but I didn't like this system for a few reasons. First, if you install it on the right side of the plane, you'll run into problems with the brake lines coming off the reservoir (at least if you have a dual brake system as I do). If you put it in the middle, you'll need to mount it near the center recess in the firewall. Didn't want to do that. And if you mount it on the left side, you're that much farther from the battery and the ground tabs I've already mounted on the firewall. I want short runs.

So I ran a bracket width-wise across the two subpanel ribs. Just cut two pieces of .063 3/4 x 3/4 angle to roughly 19" lengths. Cut the flange on one side at each end and by about 7/8" to allow the other flange to sit under the flange of the subpanel ribs.

I fit one bracket about 1 3/4" forward of the subpanel, drilled two #19 holes for two #8 screws. I elected not to put nutplates in the flange of the subpanel rib and will use screws and nuts instead. I obviously didn't rivet the angle either. Riveting is forever and I'm not entirely sure that something else down the road won't require me to move things, and this gives me the flexibility to do that.

Anyway, I installed one angle and then clamped the other angle to the subpanel ribs and adjusted it so that each bracket was flush with the control box. I marked the location, and removed the control unit. Then I drilled the aluminum angle to the flanges of the subpanel and installed the screws and nuts.

The next step is to install nutplates in the angle to mount the control unit. I elected to use AN-3 bolts (a #12 hole) instead of screws because I thought it would be easier getting the unit off when and if I needed to, using a socket set. This was a mistake. Some small screws on the VP-50 near the mounting holes very nearly interfere with the bolt. You can't get a socket set around it. In fact, you need to be very careful locating the holes on the angle.

With both angles mounted in place, I got underneath the subpanel and decided where I wanted to mount the control unit, holding it in place, and tracing the mounting slots with a Sharpie onto the angle. For a guy with Meniere's Disease (vertigo), this is the least pleasurable part about working on the panel. Whenever I'm on my back looking up, the ear canal sends weird signals to the brain and I might as well be on a roller coaster. It takes me several minutes after doing this, sitting in the cabin, to let the nausea go away. But you don't exactly ever feel good for the rest of the day.

I then removed one angle and installed a nutplate and bolted the control unit on. I checked to be sure my mark for the other bolt hole was correct (it wasn't) and drilled the next bolt hole, installed a nutplate and bolted the control until to the angle. Then I reinstalled the angle (with the control unit attached), got underneath again and traced slot holes on the angle and marked drill points, removed the angle, attached nutplates and reinstalled.


Earlier in the day, I finally removed the fuel boost pump and center cover. I don't know why I installed them a year or so ago. It all has to come out to allow me to run wires down the center, and up some conduit to the subpanel and the VP-50 unit. Of course, I couldn't find the right nuts for the Adel clamp to keep the conduit in place, so I moved on to the VP-50 control unit installation.

After I install the battery and cables, I'll probably start with the flap motor wiring and switch. I've settled on the instrument panel design, so I'll try to find a place to send it to to be professionally cut.

As always, click the image for a bigger size.

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