[grosbeak]

Thanks John. I'm pleased with my painting restraint... usually I'm impatient and I lay the coats too thick, but not this time.

[grosbeak]

Done and on the plane for a pre-balance photo. Loving the way it looks!



I wish I had thought to weigh the prop before I painted it. I do have another Xoar 18 x 8 so I'll weigh both and post the results here.

Prop balancing is next. I will try to remember to weigh it before and after!

[grosbeak]

Tonight...

I put small Monokote stripes on the wing bottoms to mark the specified CG.




I also had to drill some small holes in the wing root to allow clearance for the upper window screw heads.




Fully assembled and ready for a CG check.






CG check.

+ YouTube Video

Needs 347g (3/4 lb) of ballast on the firewall to balance.



While I was at it I measured the total weight. 7.5 kg (16.5 lb)... a little above the 12-15 lbs specified in the manual.

Just a few things left to do... balance the prop, add the ballast, final radio setup, and...

... add some baffling to cool the cylinder head. That's something I've never done before. Tips?

[Trumpetman]

Can you post some closeup pictures of the engine and cowl. It looks like you already have pretty good airflow to the front of the cylinder head but some close ups would help.

[grosbeak]

Originally Posted by Trumpetman

Can you post some closeup pictures of the engine and cowl. It looks like you already have pretty good airflow to the front of the cylinder head but some close ups would help.

Will do.

[grosbeak]

Here are the inlet and exit photos.

Inlet.




Exit, from front, and...



... below.

[grosbeak]

Baffling - here's the angle that would be needed to redirect airflow to the cylinder head.

Cowl off:




Cowl on:




Is it realistic to expect sufficient cooling airflow at such an angle, or is cutting the cowl the way to go?

[Trumpetman]

I would just open up the bottom of the cowl a bit. You could even fabricate a little scoop to pull the air up into the engine bay. A scoop would be a lot easier than building baffling inside the cowl.

[grosbeak]

While I ponder the airflow issue, here's a little more progress.

I moved the ballast as far forward as it would go - here's the platform.




Weights installed.






Screws secure the platform at the back, zip ties at the front. I have since added zip ties to the back for extra security.

[grosbeak]

Time to compare the propeller weights.




Unpainted - 64.6 g




Painted - 69.6 g. I can live with that.




The painted prop is now balanced. I had to add some clearcoat to the rear of the light blade... we'll see how much it weighs when it's done curing.


You may have noticed the negative camber of the main gear when the airplane is on its wheels.




I removed the gear and bent each of the wheel mounts inward a bit. Original bend at 76º...




New bend - 68º




Back on the plane.




Port wheel...



Starboard wheel.




I broke the #$%@! gear cover when I was removing the #$%@! packing tape that held it on. Hoping epoxy does the trick.




The use of packing tape is too sloppy for my liking. I am going to add some mounts so I can screw the cover in place.