by jcfremy » Mon Sep 22, 2014 7:11 am
Dear Sonex enthousiasts
Some explanations about my project to install a UL Power UL260i (97 cv) on a Sonex TD
My project was born 3 uears ago from a kind of wreck taking dust and mud at the far end of my hangar
It was a Sonex equiped with a old Jabiru 2200; Felt in love with this design I bought it and had in mind to refurbish completely it and mount a brand new, up to date, engine, I liked the idea of injection, without drive and water coolant design
The UL power mounting match perfectly with the Jabiru engine brackets, so it was very easy to swap them
The Jab was holding a lead weight about 15 lbs for having a correct weight balance, so installing the new heavier engine but without the added weight gave the same W/B
The tasks were to rebuilt the fuel line with the feed back to the tank, to totally redesign the electric circuitry because, the ECU, ignition and Pumps need a perfect power supply , to built a new instrument panel and to do a big maintenance on the frame and commands
AND the main task was to modify the engine cowling that took me almost the same time than the previous listed tasks....the first default or amateur is to be a bit too much optimistic ...
The engine has bigger (by far) head fins than the Jabiru one that insure a goog running temps but also a pain in... to integrate under a cowling that would be nice to observe
I choosen to install a pair of ram air boxes to be sure that, what ever the quality of my cowler, the engine will be constantly cooled
I modified the sonex cowling by sticking the right and left side and cutted it to have acces by the top and having then the possibility to operate a good checking on the tarmac with reasonable efforts to play with cowling parts
I intalled in a first time the oil cooler along the engine left side and was ducted with a Naca with poor efficiency so I moved it to the front of the engine and modified the cowling with a kind of mouth that is much more effincient but less pretty
Actually CHT's are 110 to 120°C, EGT's are 780 to 810°c and oil is 85 -95 °C what ever the external condition (tested close to 30°c on ground) and even in climb
I firstly installed an adjustable two blades (59"x51") carbon propeller that permits to cruise at 135mph@2900-3000 rpm with a top speed at 150mph @3300 rpm (20°c and 1500ft fligh test conditions) the climb rate was about 1000-1100 ft/mn; nevertheless I espected a take off running better than 600ft so I ordered a dedicated wooden two blades (58"x50") with an increase of the climb rate about 1300'/mn and shortened run for take off by 10-15% and small losses in speeds, but am not so enjoyed by this one and the engine doesn't likes too much light propeller
With the first prop I did a country tour in summer with an average fuel flow about 4 to 4.5 g/hour including take off, climbings, cruise and so on
I have (only) 70 logged since new, it starts like a car, run smoothly with a reasonable sound level (my friends said), I fill it with MOGAS 95 or 98 and sometime AVGAS 100LL
The ULPower members are nice and carefull to your questions
The price is not really competitive to Rotax
Until now I am satisfyied by this choice
Have good and safe flights
Jean CLaude