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Aug 30, 2007, 02:01 PM
Vertical Unlimited
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Nuclear e-Brio

I built an E-Flite Brio 10 a few months ago, and was a little disappointed by the power train's performance (not a fault with the aircraft). The Hacker A30-16M motor was OK, but I ended up wringing every last watt out of it and even then I found myself reaching for more power (e.g. following a vertical snap sequence). Everything about my flying craves unlimited vertical, and not just chugging slowly, but a spirited zoom to altitude. The Hacker just couldn't deliver this, even at 36A / 360W. Don't get me wrong - it was good, and the vertical was unlimited, but it was slow and didn't look convincing. My ST90 [over]powered Extra 300 was much more convincing. I suspect that flying in 100+F temps didn't help - low air density, and additional major heat load for the electronics.

I've read about Brios being powered by E-Flite's Park 450 motor in a lightweight set-up, which I'm sure many would advocate, but I went the other way. An E-Flite Power 10 outrunner would have been a good start, but I thought "let's not do this by halves". I set about specifying a system that would deliver serious watts when called, which is exactly how I like to set-up my planes. I selected the Hextronic 35-42C 1000kV motor, which is rated to 600W, a Hobby-Wing Pentium 60 ESC, and a Hextronic 4S2P 2600mAh Lipo. I could have used a 4S1P battery, but the 2P option allowed me to assemble a pack that would fit the plane better (4S1P packs tend to be very long). I also installed a Corona Rx (dual conversion) in place of my Futaba FF7 PCM Rx, to save nearly 2oz of weight. All items from United Hobbies, who've supported me very well.

The battery and ESC were rated to 1000W+, so the limit would be the motor. This degree of over-specification is essential in the heat I have to fly in, to ensure items are not operating at their limit. I retained the APC-e 12x6 prop from the Hacker as a starting point. Initial ground testing nearly blew my house down... 740W !!! Not bad for a plane that some people fly with less than 250W. Before you think "what a crazy man" remember that the key to this sort of flying is THROTTLE MANAGEMENT. I don't drive my car with the accelerator all the way down, so why should I fly that way? I only call for the power when I need it. Total weight gain from the old set-up was just 4oz.

I was a bit nervous just before the test flight, figuring "better not use too much throttle or the wings will be left behind!". The take-off was spirited, at just under 1/2 throttle! I flew a few circuits to confirm everything was OK (especially the radio - I had a lot of glitching problems with the original set-up - check out my "glitching" thread). Everything was working perfectly, so the aerobatics began. Chopper flying has taught me automatic throttle management, so it was no trouble to keep things under control. A plumb-vertical climb revealed circuit speed could be maintained at about 60% throttle - NOT BAD! The true test would come with the vertical snaps - which traditionally rob speed. A double-snap required a kick with the throttle, but it was good to have the power in reserve for exactly this purpose. The vertical line continued smoothly afterwards.

The flight revealed I got just what I wanted. A good cruising speed can be maintained in any attitude, giving the plane a convincing performance with a lot of presence. Finally I'm getting the performance from this plane that I craved. Ultimate max power loading is just under 300W/lb, although I haven't needed all of it. My only concern was the landing, but it was no drama - it still settles down for a slow, nose-high greaser. A great design, now supported by a great power train. Flight times will be 8+ minutes, depending on manoeuvres. So how fast is it? I don't fly it any faster than I did before, so forget it - this isn't a drag-racer.

The United Hobbies gear (power train and Rx) has proved to be very reliable and I'm very happy with the quality of the components - the motor is a work of art, and has happily absorbed the short bursts of 800W input power. I was a bit concerned that the ESC heat-sink was concealed inside the heat-shrink cover, so the heat-shrink was cut to get some air to this component. I ended up installing a bigger heat-sink and also a mini cooling fan - you wouldn't believe the heat I fly in! The 4S2P battery also worked well.

Straight Up, unlimited vertical Brio. Next stop, the Moon.
Last edited by Straight Up; Aug 30, 2007 at 02:21 PM.
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