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The Start of The SAB KR84 Design and Build.

Wildthing

Legendary member
Went to the field yesterday and the first thing I saw sitting on the bench was the guy's Sab KR-84 and there was his bungee launcher all setup, dang it I wish I would have known mind you I hadn't set them up yet in the new Jumper T16 tx so today I made sure both of mine are in it so I am ready to roll next time he sets up. :)
 

Wildthing

Legendary member
Well both SAB KR84's got their maiden flight in and both came home in one piece. 4S version (black) did really good but I was heating up the motor pretty good towards the end, it actually started to fluctuate in rpm. Going to prop it down slightly and maybe redo the cowl and see if I can get a little more air to it . The 6S version (orange) got some issues going on with the big cheap Red Brick 200A esc, at half throttle you could hear it stutter, at full it would go away but really only once did it hit a decent rpm so we will disect out that esc and I think I will prop it down a bit also. Launches on both went super cool .


 

Wildthing

Legendary member
Well the dud 200A esc is out of the 6S version, next to find and wire up a new esc that doesn't stutter. The 4S guy instead of propping it down I am going to a slightly less kv motor, it had the NTM 2836 3000kv , 80A esc and 6X3 TGS prop. Because I had smucked up the T50 and it had the 2700kv motor in it and there it was sitting looking at me it is going in and will be spinning the same prop. I am printing out a new nozzle which will hopefully allow some more airflow by the motor.

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bracesport

Legendary member
Well you can not complain about that effort - are they easy to spot in the flesh than on the video!?! :ROFLMAO:

Well both SAB KR84's got their maiden flight in and both came home in one piece. 4S version (black) did really good but I was heating up the motor pretty good towards the end, it actually started to fluctuate in rpm. Going to prop it down slightly and maybe redo the cowl and see if I can get a little more air to it . The 6S version (orange) got some issues going on with the big cheap Red Brick 200A esc, at half throttle you could hear it stutter, at full it would go away but really only once did it hit a decent rpm so we will disect out that esc and I think I will prop it down a bit also. Launches on both went super cool .


 

Wildthing

Legendary member
Well both boy's are back together and ready for test #2 . The 4S version went from a 3000kv NTM 2836 down to a 2700kv motor so that should help with the heat and still give the same thrust. The 6S has a 80A esc instead of that Red Brick 200A esc , no stutter anymore all the way through to full throttle. To be somewhat forgiving I propped it down slightly to, went from a 7X6 to a 7X4 , if things go good and there is no magic smoke or flames I will bump up the prop. On both I also increased airflow to the motors.

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Timmy

Legendary member
Well both boy's are back together and ready for test #2 . The 4S version went from a 3000kv NTM 2836 down to a 2700kv motor so that should help with the heat and still give the same thrust. The 6S has a 80A esc instead of that Red Brick 200A esc , no stutter anymore all the way through to full throttle. To be somewhat forgiving I propped it down slightly to, went from a 7X6 to a 7X4 , if things go good and there is no magic smoke or flames I will bump up the prop. On both I also increased airflow to the motors.

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How is it so clean over there!??!?!
 

Wildthing

Legendary member
Almost a year ago when I last flew these guys. esc change (smaller but the largest I had on hand 80A ) for the 6S version so it also got proped down and the 4S one got the motor changed to a slightly lower kv, one of my old trusted NTM motors, not the new Prop Drive V2. Well they went up again today, 4S is fast but the 6S was disappointing but with the 6S when landing I glided in smooth but I think the bunjie chord hook caught something and it dug the nose in hard, it is officially in the trash now :D . It was funny launching it and a very good thing my friend has a very long and very strong bungy chord because I forgot to turn off the kill switch and I was launching with the wind but flipped that switch just in time.