Hi,

It states very clearly in manual not to use more powerfull turbines than 16kg class unless you have modified it. We at Skymaster has tested with all kinds of turbines. A 12kg thrust turbine can do all the aerobatics at 5000ft including smoke on board. So a 16kg should be more than enough...

Please be carefull when powering the Viper with 20kg+ thrust going flat out!!!

Regards

Morne