I would assume this Viper will be similar to the Skyangel 50mm T45 ... which I have two of.
CoG is of course set xx back from LE of wing ... but when I modified mine to have 5000kv on a 5blade - I put in a 1600 4S pack ... CoG ended up on the LE where it joined fuselage. I thought ... yeh yeh yeh ... this will be a disaster. In fact it hardly changed her at all - but BOY what a flyer !! I tried a smaller 4S in her but flight time was too short ............ Original was 4300kv on a 5 blade ... with factory spec 800 3S ........... total crap !! It flew but an 800 was just gutless. I put in a 1500 3S and it became a hot flyer .... and then the Need for Speed group was running on Wattflyer and along with my Parkjet - it was into 4S .... I pushed the limits of the T45 in the end that I used a bungee to get her in the air ... especially when I put the heli motor on the back end of one with a 4.1 x 4.1 prop ..... INSANE !! AS GBL has found in the Viper - these 50mm EDF's are a very nice size ... fly well ... we just need more !!
I'll fly anything if I can launch it ! Youtube : solentlifeuk