My Sonex Project

[Matt541]

Another short flight in 541, can't wait to start stretching it's legs a bit.
(I do film all of my flights in it, but not everything gets edited and posted. Helps me to learn from.)



541 flies great and that Revmaster engine is purring like a kitten. This time it was my old AveoWare (MGL) flight instrument that let me down. The screen would fade away and come back, not a huge deal, I'd just lose indicated alt and airspeed for a moment. I've learned that she'll let you know when she's slow and I could certainly fly the wing. But why take the risk?

I also learned never to land in the grass on the 19 end at Slatington, boy was that rough! (I'm glad I made the Bob Mika landing gear improvements...) Apparently they used to roll the ground with larger barrels full of concrete to smooth everything out, but it's been a few years since it was done. Plus, after the tornado, I won't be doing any grass work there period for some time.

I ordered a new MGL Blaze ASV-2 gauge and am about 90% of the way into installing it.

[BRS]

Hi Matt,

Just reread all seven pages of your thread and watched many of your videos. I was looking to see if I could get a good picture of the front lower cowl. I've had to cut many holes in order to get the RM oil cooler and carb to clear. Now I have swiss-cheese and will eventually have to hone my fiberglassing skills. Do you use the RM filter and ram air valve?

Today I filled the tank for the first time and mounted the prop. Seems I'll likely run the engine tomorrow.

[Matt541]

Nice! That's a big moment.

I found some old pics inside and out of the cowling I took for another Revmaster owner. I'll be at the hangar today and can get more if needed.

So, yes I do use the RM butterfly valve and tube with a K&N filter. But my filter is much longer than what RM currently shows. This actually causes a bit of an interference issue with the bump out and carb heat lever. I need to try the shorter filter or glass in a new bump out. I really like what Dave Misner did using an RV air scoop though. Plenty of room there.

[WesRagle]

Hi Matt,

Enjoyed the video. I couldn't help but notice that last frame where you're trying to get behind the panel to install the new instrument. Just about every Sonex builder has been there. The older you get the harder it is. Contrast that with the Sonerai. Here is a pic of the Sonerai with the cowling off. Note that the fuel tank is out but removing that is an easy chore.

Somebody needs to talk to John M. about combining his best ideas in a single airplane. I ain't do'in it.



Wes

[BRS]

Nice! That's a big moment.

I found some old pics inside and out of the cowling I took for another Revmaster owner. I'll be at the hangar today and can get more if needed.

Thanks for the pictures. Matches the current holes in my cowl except I don't have a clearance issue under the oil filter that yours seem to have had.

Engine ran fine this morning. Ran it long enough to figure out what was not yet working (ie. EGT reading negative). What rpm does your's like to idle at?

[Matt541]

After some recent incidents involving the canopy opening in flight, I finally broke down and ordered the neat canopy latch being sold by Peter Anson. I've had my eye on it since the Virtual Fly Ins. Figured I'd grab some more goodies while I was at it:



Short vid, but there's some close up shots if you've been thinking about ordering from him as well. Everything was packaged well, no issues, and appears to be of top quality.
Just keep in mind that it can take 2-3 weeks to receive your order.

Now I just have to be able to get to the airport to install them and other things.

[Matt541]

I recently helped Mike prep new Azusa Tri Star wheels for his Waiex, after I had the same problem with mine. If you're noticing some serious wobble in your wheels, this is what you have to do:



It's worth noting that Azusa appears to be sanding the flashing from the bolt holes now before sending them out. However, some of them went a bit too far leaving a gap. I had Mike order at least 3 wheels so I could pick the best ones.

This is one of those videos I filmed during Sonex Rehab 2020, but never put together. Some of you wanted to see how it was done, so I took the opportunity to get some newer better footage as well. Let me know if you have any questions. Enjoy!

[Matt541]

Been a while since I posted an update, big part of that is I simply haven't put anywhere near as much time flying as I'd like to. Life and what not.

One of those reasons was the dreaded Revmaster overcharging issue:



Others have posted about it here, but I think Glenn Bradley has the most experience fighting it. (Most experience flying behind them as well...) The main point is that the RM engine has two permanent magnet alternators that from the factory run all the time. For whatever reason that someone smarter than me can explain, this can cause the system to overcharge and fry components. Anything over 14.6V is too high, but I've even seen 17.6! (briefly) Turning the Master off typically resets the system, but you have to keep an eye on it. Sounds like the voltage regulators aren't able to do their job under that condition, but why? Again, I don't have the answer.

But I can say that at least for now, putting a switch in the system to allow only one charging at a time keeps the voltage in check. I chose to go with a single DPDT switch, but you could put a normal switch for each. (Already have 4 ignition switches, didn't want 2 more for the Alts.) I've heard of others having issues even while running on only one, time will tell. Some have gone to great lengths to redesign the system outside of the stator.

Either way, I can honestly say that the Sonex itself has been great, my primary issues so far have been with the Revmaster's systems. Guess that's all part of being on what Brian Carpenter calls the "Experimental" side of the development bell curve. (Told him he needs to do a video on that!)

In other news, my LSRM class with the Carpenters at Rainbow Aviation was great! And I start as an Apprentice for an FAA repair station Monday. 30ish months, a lot to learn and we'll have one more A&P that isn't afraid of Experimentals...

[Matt541]

Check your panels!
I aborted a takeoff due to the airspeed not coming alive, did some searching and found one of the 4 types of tubing used in my pitot static system had cracked and broken in multiple pieces. There was even a couple chunks present in the clear tubing.
So, if you see any of this green polyurethane tubing, get rid of it.!



I believe it's a combination of age and proximity to the plastic fuel tank. It's worth noting that there's also clear and yellow tubing in the same area without issue. (And now there's only 2 types being used...)

[BRS]

Matt,

Thanks for the latest videos. They are always fun to watch.

As for the RM charging. I installed mine with two SPST switches so that they can be run together or separate. My battery is an EarthX which draws enough current, when discharged, to burn up the RM charge coil windings. So my proceedure is to turn both alternators on while still warming up at idle. This gets the battery up to 14.1 in about 3 minutes then I turn one off. One of my alternators is wound with only 4 coils and the other 5 (normal). So I generally fly with the 4-coil alternator as it produces plenty of current.

Overcharging: Still, like you said, the regulators sometimes get distracted and forget to regulate. I've see 15.5 Volts. Resetting the circuit does fix the problem. I think that the addition of a crow-bar circuit (w/resettable CB) would be a nice addition to our RM charge circuits.