ORIGINAL: Strykaas
What about the counter-rotating mechanism ? Is it custom made ? Or can we buy it somewhere ?
Nothing that complex - it is as easy as it gets: AXi makes a beautiful twin 5330 for bigger aerobatic and pattern models, where both shafts are coupled. Inside the MC-72, the two shafts are completely free to rotate: by accurately programming each ESC (you need two ESC, 90A-size), he made the front motor turn clockwise, while the rear motor turns counterclockwise. Propellers have been custom made for this beauty by a friend of the builder/pilot. Each motor is powered by its own 9S lipo pack, they are Polyquest XP 3700 mAh cells. If I remember correctly, ESC are two Jeti opto 90.
The engine is sold wherever AXi's are sold: it is called (helpfully) "AXi Twin" or "Double 5330"; according to
www.hepf.at there are 3 sizes.
[link=http://www.modelmotors.cz/index.php?page=61&product=5330D&serie=20&line=GOLD]Link to Model Motors' Website[/link] with specs and data.
Builder/pilot Martin Biller of Markdorf (Germany) once told me that he would write a report on a german magazine: I hope it will be soon!
The Pegna PC-7 is a plane that I like a lot: now with electrics it shouldn't be impossible to do: it has been done with IC engines... Will need some plans and data, but will definitely look into it in the future!
Regards,
-Fabrizio