Another parts problem

[ksatter26]

Still awaiting my lift strut inserts so I'm rapidly running out of little things to get done.

The port wing is mounted in-place on the fuselage with the flaperon clecoed in place. I have the lift strut attached to the lower mount and tied off (too long) at the forward and rear spar mounts ready for measuring and trimming to install the new inserts so I can get to work on the jury struts. I also installed the BADLANDS butt rib at the fuselage end.

With this done I tried routing the flaperon control cable to get an idea of location and attachment of the flaperon control arm. My original control arms were incorrect (tubing went OVER the flaperon spar) so Chris replaced then with the later design (fits INSIDE the spar). The port fitting is perfect and I'll be able to align the control arm arm and cable when the wing is finally aligned/secured properly. HOWEVER, with little things to do running out and time/weather OK, I took a look at the starboard wing/flaperon ... currently hanging from supports on the hangar door. I found that Chris had sent me TWO PORT flaperon control arms. I fired off an email and he's sending out a replacement. He must me house-bound in the Minnesota winter as the response was super quick.

Still running trials of where/how to mount/modify the nice bubble cowl. Chris says ok to replace the bulky air box/filter with a much smaller motorcycle filter. This will require a much smaller hole/protrusion on the port side of the cowl. On the starboard side, he suggested I put a light-source inside the cowl to mark where the exhaust system may need to extend outside the shape of the cowl ... excellent idea. I'll also have to trim the lower end of the cowl to allow the tip of the exhaust pipe from the muffler to extend below the cowl. Still not looking forward to messing with that nice cowl.

Almost 70 degrees yesterday but typical of North Texas weather, a front is due to pass thru later today ... winds/rain/hail. Gets pretty noisy in the steel hangar shop ... drowns out NPR on the radio.

[LA F2 Flyer]

I'm curious to know if changing the air filter requires a significant change in jetting. I may have to ask Chris the next time I talk to him - long overdue as it's been a while!

And the "adding a light source insode the cowl" to mark the cutting points is brilliant! I love it.

[Badland-F5 Pilot]

I'm curious to know if changing the air filter requires a significant change in jetting. I may have to ask Chris the next time I talk to him - long overdue as it's been a while!

And the "adding a light source insode the cowl" to mark the cutting points is brilliant! I love it.

The answer to the change in jetting should be no change. This is info from way back when I was in auto shop, but here goes – when looking at the air box on the Polini, it's fairly large. This means the vacuum (negative pressure) from the intake is fairly low. Replacing with a smaller filter closer to the intake does not increase or change that negative pressure much at all. The discussion came about when our shop teacher was telling us about the larger and smaller filter boxes on engines. You remember those big round filters on old cars? The volume of air pulled in by the engine is the same so that's a constant. As long as the filter's flow capacity to transfer air is more than the intake on the engine, there's almost no difference at all in negative pressure from the vacuum, so no adjustment should be needed.

And a trick my dad taught me a long time ago when having to deal with something that requires a hole, but you can't really see where the hole needs to be cut is to use snap line chalk. It's messy but sprinkle a little on the part that will touch the inside of the cowl. Put the cowl on carefully and just tap it where it touches the part inside, then pull the cowl off. The chalk will show you where you need to drill through and start cutting.

[LA F2 Flyer]

Interesting. It makes sense about the jetting.

As for the chalk line chalk method, also a good tip! And definitely a better option if your fiberglass is thicker and won't take to shining a light through it. It was always a struggle making that first cut when I was fabricating fiberglass parts for my race bikes. I used a similar method, but with axle grease. The chalk would have been a much cleaner way to go!

[Badland-F5 Pilot]

Interesting. It makes sense about the jetting.

As for the chalk line chalk method, also a good tip! And definitely a better option if your fiberglass is thicker and won't take to shining a light through it. It was always a struggle making that first cut when I was fabricating fiberglass parts for my race bikes. I used a similar method, but with axle grease. The chalk would have been a much cleaner way to go!

I also used the axle grease method, but found that cleaning up was just as you said, a mess and if not all removed would prevent anything else including more fiberglass from sticking to the existing fiberglass. A sort of delaminating would take place, and then it became a do over