Heater flapper install, intake tube mods | 1.31.2021

Finally got around to installing the heater flapper control. Basically needed to mount the control, route it through the canard bulkhead, and connect. Started by fabricating the hardpoints and figuring out the mounting location. The best mounting location I could come up with was on the pilot's left hand side on the fuselage. Since the control would need to be canted out, I made the front mounting point out of 1" (if I'm remembering right?) square aluminum. I then installed a nutplate in this.

The control was then installed to the hardpoints with adel clamps, and the hardpoints were structurally adhered to the fuselage and secured to the fuselage to cure with rivets.

Ready to adhere.

Installed location.

I then routed the cable through an existing hole in the bulkhead. Not the most optimal location, but I wanted to use an existing hole rather than make another. The cable was trimmed to length, and the rest of the hardware was installed per plans.

Works great!

 

I then started working on what is the most "experimental" thing I've done on the plane so far. To sum up the problem: the exhaust doesn't fit with the intake tubes. It interferes with the front (rear? closest to propeller. cyls 1+2.) two intake tubes. I could dent the exhaust and make it work, but that's non-ideal. Additionally, those same intake tubes interfere with the cowling fit. I was going to need to cut and bump the cowling for them to fit anyway, so I was already looking for alternatives.

The alternative options started with looking at cold air intakes. All of these kits feature more "tucked" intake tubes, so they would all work for me. The only issue with all of them is that they all flip the intake around to the "front" of the engine. This works *great* on a plane where the front of the engine faces the front of the plane. You get a bit of ram air into the intake and thus a tiny bit more manifold pressure and more power. The problem is that the Velocity intake solution is hinged on an intake that faces the "rear" of the engine. Additionally, I did some measuring and it looked like I'd need to bump the cowling for the fuel servo if I did that.

I called and talked to at least 4 custom shops about this. All of them had a >2 month lead time, as they were slammed with work. All of them recommended the same thing: nip/tuck the existing intake tubes. After talking with some local friends, I determined that I could cut and tack weld them, and then have one of them complete the welds (I'm a terrible welder).

Section removed

 

I started by cutting about 1" out of each intake tube. The tube was then rotated up, keeping in line/parallel/plumb with the sump intake holes. The inside of the existing curve was then cut 90% of the way through, and the tube was "unfolded" to meet up with the short bit hanging off the cylinder intake port. I then tack welded these in place. The small gaps will need to be filled when they're welded up, but I've been told it's not an issue.

Tacks were placed on both sides to hold the geometry.

 

Once they're welded up, I'll run an appropriately sized flexible flap wheel through the inside of the tubes and then clean/polish them up with a flexible hone.

A few homebuilders friends also stopped by to have a look at the build and look stuff over. Recommended a few changes with some hoses, but said everything is looking great.

That's it for now!
- Jeff