Originally Posted by kaiser_solsay
Im thinking about replacing the standard 400 motors with 2 x 6/20 Typhoon brushless motors powered with a 3c 2600mAh.
Do you think the 6/20's will be up to the job? Are they a good motor?
Kaiser, I don't know much about those motors, and a little Googling turned up only the Kv (rpm/volt), not the motor winding resistance or no-load current.
That said, the information I found says the motors are rated for 12 A continuous current. That means these motors put out the right amount of power to breathe life into a Twinstar II, they are capable of a little more power output than the Esskay 400XT motors I'm using.
The Kv of these little Typhoon 6/20 motors is rather high at 1800 rpm/V, and you will have to use correspondingly smaller props. I suggest an APC Thin Electric 6x4 as a starting point. Using the sophisticated WAG method of guessing at the motor resistance and idle current, that prop should pull around 11 A and put out about 18 oz of thrust and 60 mph pitch speed. Sorry, just noticed you're posting from the UK where you don't have to deal with these inconvenient imperial units, so that's about 510 gm of thrust and 96 kmph.
The pitch speed is on the high side for the Twinstar, sacrificing thrust in exchange for speed, but I don't see a lot of pitch choices for 6" Thin Electric props on the APC product page (though they do make a 6.3x4 combat prop, and a 6.5x2.9 free-flight prop, which might be worth a try - I know nothing about those product lines, unfortunately, but if it works that last prop should produce a better balance of thrust and speed for the TS-II).