|Mar 25, 2012, 01:20 AM|
UMX Sbach on 3s
Warning: The AR6400NBL brick is not designed for 3s. Some bricks handle it, many don't. Try at your own risk.
Experimenting with running a Hyperion 3s 180 mAh 'Babbelbatt' on a stock Sbach with a 5030 prop. Per RC's recommendation, I'm only charging the packs to 12V to prevent damaging the brick from too much voltage.
For the first flight, I mounted the pack all the way aft. I soon found that the plane was far too tail-heavy for high-speed flying, so I landed & moved the pack forward a bit. Much better. The plane is ridiculously fast. This thing goes faster straight up than an Sbach on 2s can go straight down! With the aileron pushrods in the second from the outermost holes, it can effortlessly do 'the drill-bit maneuver' vertically! The motor & pack were just barely warm after a 4.5 minute flight. Put 108 mAh back in, starting from a 12V charge.
On the second flight, I moved the CG further forward for better high-speed tracking, and set up dual-rates. Much, much better! No more darty behavior at high speed. She tracked straight & true even @ WOT. Again, the motor & pack were barely warm after the flight.
The plane is a blast to fly on 3s! I've never seen a plane with such a wide flight envelope before. Slow to a crawl or sport-fly at 10-20% throttle, perform pattern aerobatics at 25-30% throttle, perform any unlimited aerobatic maneuver you can possibly think of without ever going past 40% throttle - and you still have 60% throttle for headroom! Balls-to-the-wall, she can easily keep up with many 40-60-size glow-powered ships! Absolutely amazing! I really, really like low-rates when flying at high throttle settings. I rarely use low rates - but this an exception.
I did not detect even a hint of flutter. She seems to be perfectly happy flying at nearly twice her design-speed.
Since I had no trouble getting the CG back far enough to make her very tail-heavy, I decided to go up for one more flight with a Hyp 320 2s pack. Surprisingly, the CG was about right for general aerobatics with the pack all the way back. Vertical wasn't as good as it is with a Hyp 240, but the plane should fly for ages with that pack. A good choice when flying in windy conditions, where a bit of extra weight can be a good thing.
One thing that would make it even better would be AS3X. I will definitely be installing the programmable AS3X brick as soon as they are available.
|Jun 13, 2012, 10:59 PM|
Joined Apr 2012
So your brick is one of the lucky ones!!! I'm surprised u haven't fried it. My sbach is pretty fast already. So i can only imagine it at almost 2x the speed for just a battery upgrade. Must be a sweet flying rocket!!
|Jun 14, 2012, 08:02 AM|
Yes, it looks like I won the 'brick lottery' when I picked up my Sbach. I have a second Sbach that's optimized for indoor flying, and I will not be trying 3s on it!
A few of us started experimenting with 3s & it went from there. I am now running fully-charged 3s packs with no problems, as are a few others. However, I think that considerably more than half of those on the thread who have tried 3s on the AR6400NBL brick have fried it, and some were using short-charged packs. It's definitely a voltage issue, as the bricks usually pop immediately upon connecting the pack. In contrast, the Beast 3D brick seems to handle 3s quite well.
She's definitely a rocket on 3s! We're talking over 300W per pound! Despite her 50+ MPH top speed on 3s, she can still slow down to a crawl - just like she does on 2s. However, she becomes very sensitive at high speeds. A gentle touch on the sticks is required when flying at such high speeds.
Many of us are running 3s in the Beast 3D without any problems. So far, we have not seen any reports of B3D brick failure on 3s. AS3X dramatically improves high-speed handling & makes flying on 3s a lot more fun, as AS3X planes fly similarly to IMAC ships, rather than twitchy little foamies. In fact, a number of us are putting the new user-programmable AS6410NBL AS3X brick into our Sbachs as soon as they're in stock. I hope it is as tolerant of 3s as the EFLU4864 AS3X brick that's used in the Beast 3D, Gee Bee, and Carbon Cub.
See the regular Sbach thread for lots of info on prop & motor combos, packs, handling improvements, and AS3X conversions.
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