Building a Sonex Aircraft: It's been a while hey!

I had been thinking lately that it's really far overdue that I updated this Blog and describe how the engine conversion all worked out for me. Essentially, the conversion has been the best thing I could have done. The performance is amazing, and the reliability now makes my flying enjoyable. It's as simple as that.

I have had some teething issues along the way. For example, making a few changes to fuel lines, in regard to trying to get the red cube reading a bit more accurately, but that hasn't helped much. I think the pulsations from the fuel pump tend to make it read higher than normal and a bit varied. The fuel flow in real life is essentially the same as every other Rotax out there and I plan on 18x litres/hour. I do generally cruise at a rpm a little less than the standard 5000rpm as the prop is a bit coarse so 4800-4900 rpm just seems to feel better.

Climb rates are not mind blowing compared to some other Rotax powered planes due to the prop I have which is definitely a bit too coarse in pitch. I am not really prepared to change it yet, or at all, as the performance is fine in my opinion. I have been keeping in touch with a few other builders with the Rotax installation and compared figures for this and that, but they all seem to be on a general basis the same, as one would expect really.

I am now doing more away trips since the engine has been fitted, solely to the fact that I feel more confident in the plane's ability to get me home. It really has given me a new freedom that is hard to describe. My biggest regret is that I didn't do this sooner.

The plane has clearly picked up some new characteristics from the change however. I would have liked to move the engine probably another 1/2 inch. I moved the prop hub a full inch forward but the weight and balance is just a little more aft than what it was with the Turbo Aerovee. I am used to it now but in those first few flights, I really noticed the difference. Coming into land also is quite a change. Especially with this prop. The plane tends to want to keep flying even at idle and I really need to pull the nose up to slow it down. The best way to describe it is that it's much like flying a RV9, if you poke the nose down it'll speed up too much on final. I know that is rather a basic (no shit) effect but it is way more pronounced now with the Rotax. I have done about 100 x hours now with the engine and am quite used to it but I'm glad I got to experience both engines and their flight characteristics. The Rotax out performs the Aerovee in every aspect except Aerobatics. I do miss the Rotec TBI that I had on there and the simple oil system the Aerovee had. I really miss doing stalls turns and so on. Spins also tend to throw a bit of oil out of the oil can and it can be seen on the underbelly. I think the Aerovee felt more balanced too when doing Aero's. I am far from an expert on this but it is just my personal opinion from flying both configurations in the same airframe. I also tend to need more rudder on climbs. Also when backing off the throttle, if I do it too quickly, it will really yaw the plane quite distinctly.

Emily did have good intentions to get over her air sickness every time she comes flying but that hasn't been going too well.

This was an older photo but I still love formation flying and we are going to try to do more regular flights this year.

Photo not long after the install of the Rotax.

One of the first flights away from the home airfield. Mullewa airfield and actually the first time I had landed there. There was not much to see but just somewhere to go.

Another formation day.

Annndddd another formation day.

This is a pretty standard cruise setting and may be a bit higher than normal. I tend to mostly cruise around the local area at about 125kts as I'm in no rush to go anywhere so why burn more fuel. Don't pay too much attention to the fuel flow in the pics. It's reading too high, so is the volt meter. Also the Amp meter is backwards.