Hello and Two Questions

[alarmedmutant]

Hello All,

I just purchased Sonex 642, tail number N259WB, which was built by Bill Brown in 2004 in Minnesota. The aircraft is very well-built from my limited knowledge, and it looks great. I hesitated a lot about how to take my first flight, but was reassured that Sonex landings were easier than some cropdusters I had flown, which was true.

I have a few questions I am hoping to get some help with.

1. Has anyone dealt with the Aero Conversions throttle rolling back the RPMs? During the ferry home, I could not get the RPM to stay constant no matter how hard I tightened the friction knob.

2. Any rules of thumb for how much oil cooler to block off? The ground temp was about 40°F, and I flew between 2-5K MSL, and the oil temp was about 125° at 2400 RPM on the Jabiru 3300.

Thanks everyone! I had a bunch of other questions, but the search function answered them. This forum seems like a wealth of knowledge.

-Adam

[dcrabtrey]

Checkout
http://sonex604.com/
AeroVee Modifications/Oil cooler inlet reduction

[GraemeSmith]

Adam,

Second owner like me! Welcome.

Throttle - There is a leather washer between the throttle arm and bracket that might need some attention. Even when set up correctly and appropriately lubed - I have to tighten the nut pretty hard to get it to hold a power setting. Part number 7 on page 4 of the throttle manual found here:

http://www.aeroconversions.com/support/ ... nstall.pdf

Cooler. Tough to give a specific as the cooling slot could be any size. I know I had to double the area of mine from as built for hot summer operations. Which meant I needed to make some removable baffles for winter cold. My New England oil cooler "summer smile" is about 9" wide. In the winter it is baffled down to 2". Mine points to an oil cooler mounted under the engine on an AeroVee.

YMMV

Reason they are EXPERIMENTAL - feel free to fiddle!

[builderflyer]

Hello All,

1. Has anyone dealt with the Aero Conversions throttle rolling back the RPMs? During the ferry home, I could not get the RPM to stay constant no matter how hard I tightened the friction knob.

2. Any rules of thumb for how much oil cooler to block off? The ground temp was about 40°F, and I flew between 2-5K MSL, and the oil temp was about 125° at 2400 RPM on the Jabiru 3300.

-Adam

Hi Adam, congratulations on your new purchase. Hopefully, you'll enjoy it very much. As you are finding out, the 3300 powered Sonex is exhilerating to fly while being a pussycat to land at the same time (at least when the wind is not gusty).

Regarding your first question......since installing the Aeroconversions throttle quadrant, I have experienced the same throttle slippage as you have. I've tried different materials to replace the leather washer with no success. I'm currently flying with a second leather washer on the opposite side of the throttle lever from the original one. This seems to help somewhat but the slippage is still quite annoying. I've thought of roughening the surface of the throttle lever itself between the two leather washers but haven't yet tried that. I suppose it would be necessary to roughen the surfaces of the retainer and bracket as well.

Regarding your second question........the first suggestion I would offer to get your oil temps up a bit would be to cruise at an rpm that is more appropriate for the 3300 engine and that would be at least 2750 rpm or so. That will bring the oil temps up somewhat. I live in California but in the wintertime I block off about half of the oil cooler itself with gorilla tape to get the oil temps up to 190 degrees or so. You'd have to experiment with exactly what amount of blockage it takes in your climate.

Wishing you good success with your new toy,

Art,,,,,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,,Jabiru 3300 #261

[DCASonex]

I am using a Bing with custom dual throttle on my 3300 so no help there, but I have a TOCA (Thermal Oil Cooler Adapter) that only opens flow to oil cooler when temperatures get up near 190°F and found that the air entering the cowl from the standard slot under the prop let too much air flow across the fins on front of the sump of the engine keeping it much too cool most of the year. (New Gen 4 engines do not have fins) So cut a new inlet farther down on the cowl below the sump to feed air to just the oil cooler which lets the TOCA do its thing and keep oil temps up where they belong. In Winter i close off the original slot, but partially open it in Summer.

David A.

[alarmedmutant]

Checkout
http://sonex604.com/
AeroVee Modifications/Oil cooler inlet reduction

Thank you. I should have figured this website covered that topic.

I contacted you a while back about your Barnstormers' ad. Did you get your plane sold?

Adam

[alarmedmutant]

I went and found a new friction knob that has a slightly larger diameter and better knurling (the correct werd?). I also roughed up the surfaces where the leather washer rides. Today, I am going to take my third flight to do some pattern work if the weather holds, and I will see if it works. It is still about 40 degrees F here in Southern MN, so I am going to try to block off part of the oil cooler and I will run the engine faster. I look forward to making my way around the pattern at about 150 MPH. :)

Thank you all for the info and the PM. Again, this forum is great.

Adam

[kmwoody]

Hi Adam,

I had the same throttle problem and ordered a three arm knob to replace the original. Full resistance control after that.
After I bought it online, found out my local hardware store carried them.

Ken W

[kmwoody]

Adam,

For question #2, start with blue painter tape across the whole opening and see what happens to your temps. I ended up making a cover for my "smile" and worked up, by drilling bigger holes, to 3/4" in the center with a 1/2" hole on either side of center for summer use and blue painter tape, over the holes, for winter use.

Ken W