RE: L-39 engine
Hi,
Mine has a TJT3000 in it, 28.5lbs with 1.2lbs lost in the tailpipe (static so may improve in the air), I fly off tarmac with around 100-120 yards take off run, in the air it's almost spot on as you have to fly it in a scale manner. If you're off grass then would recommend going up a step powerwise.