SonexBuilders.net

I flew in 80 degree weather for the first time yesterday, and the side vents seem to be doing their job well. Highest CHT on climbout was around 325F. Angle of attach doesn't seem to matter.

I also have my carbon monoxide issue under control. As it turns out there were some leaks in the lower bottom corners of the firewall that light didn't reveal. I ended up buying a theater fogger and set it on my seat, pointing towards the firewall. I then put my shop vac in the blow configuration, and pressurized the fuselage slightly by blowing air into the access port in the tail. I was able to see the fog coming out of every place I hadn't got a tight seal. The CO level is now less than 10ppm when in cruise with no exhaust smell (perhaps less than some other Sonexes). With the cowl off on the ground, the CO level doesn't go above 2ppm. I've considered putting a lip in front of the side vents to help lower the cowl pressure, but everything is working so well now, as far as cooling, I don't want to change anything.

Hi Paul,

You said that the highest CHT on climbout was 325 degrees. Is that right? Seems very low. The AeroVee manual states that CHTs during cruise should be around 350-375. What type of equipment are you using to measure temperatures?

-- Michael
OneX N169XE

I think the Jabiru max continuous cruise temp is 356F. In cruise I lean to around 1300F EGT, and my hottest CHT is around 315F.

I'm using a GRT EIS 6000 engine monitor.

Now that my rough time with CO has been mostly resolved, I'm really enjoying flying the Sonex. It's going to be even nicer now that I just got insurance. $2200 for full coverage is a little steep, but I was expecting it to be for a 160hr pilot in a plane with about 18hrs. I'll definitely shop around again next year, as I hope to have much more time by then.

My brakes haven't worked too good since the beginning, but were starting to get better until I got grease on the right disk last week. I think initially I had gotten the silicone based brake fluid on them, but is was starting to wear off. The challenge will be cleaning the disk and pucks without getting brake cleaner on the tire.

I have a Prince 54x60 P-tip prop, and the performance feels great, but I'm only getting arout 2900RPM on takeoff, and approx 3100RPM strait and level at WOT. I've heard that people are getting 3300RPM during climbout with other types of props, so I'm going to investigate this a little more. Perhaps cold air induction has too much restriction?

Anyway, I'm gaining more confidence in my Sonex, and having more fun every flight. Hopefully today the weather will cooperate.

Just an update on the cowl side cooling vents.

They continue to work excellent for cooling the engine. However, on the ground I had still been getting 30 - 50PPM carbon monoxide. This isn't a safety issue, but I wondered if I could do better. I recently taped a 1/2 inch aluminum "lip" bent at 45 degrees to the front edge of the cooling exits. This made a dramatic difference; now the highest carbon monoxide level I see on the ground is around 12 PPM, and most of the time it's around 9 PPM. During flight it's in the 6 to 9 PPM range. I'm very happy with this result.

I may cut the aluminum lip down to 1/4 inch, and if that works, replace it with a permanent fiberglass lip.

EAA announced that they would partially reimburse chapters for approved tool purchases. My chapter jumped at the offer and bought a dynamic prop balancer.

To my surprise, my first reading was almost 1.00 IPS. (Inches per second of vibration acceleration).

I contacted Lonnie Prince to get his thoughts, and sent him the following picture that shows my counter balance solution. He seemed to like the solution.

With this counterweight, I was able to zero out my imbalance, and the engine runs much smoother, and produces a little more RPM at full throttle.

https://1drv.ms/u/s!AKvegj5EiW7apio


https://1drv.ms/u/s!AKvegj5EiW7apis



The weight is approx 48 grams, which is quite a bit. Two other chapter members had to add 20 too 30 grams to their planes.

Paul,

What are you using to post photos ? Sometimes folks photos show up directly on the forum digest, other times have to go into the website, but cannot find yours at all.

David A.

Hi David,

I was using iCloud, and then also tried OneDrive. Neither one of them is giving me a link with a ".jpg" extension. I edited the post, and copied the shared OneDrive line above each image, so it should take you to the public shared picture location.

Paul,
Does the weight shift around since it appears to only be attached in the center. I would think it might move / spin around the center attachment prop bolt

Paul,

Thanks, those links work fine.

David A.