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Old Feb 20, 2013, 09:50 PM
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LiFePo4 cells are 3.3V nominal. Your 6S LiFePo4 will be a 19.8V pack (nominal). That's the voltage you should be using when figuring head speeds, selecting pinions & motor kVs, etc. I wouldn't match it with a motor spec'd at 18.5V max., others might though.

Guys have used A123 batteries on the Swift, which are LiFePo4 chemistry, but they had to innovate and come up with custom ways to mount them as they are/were (?) larger than 3.7V Lipo cells. The NX may have more mounting options as it has a larger canopy. Not sure what the largest battery size is though ...
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Old Feb 21, 2013, 02:30 PM
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If you can get a hold of justplanechris, he has used a123's in his swift.
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Old Feb 21, 2013, 04:31 PM
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In my experience, it required more A123 cells then Lipo cells for the same power under load. This was also confirmed early on with my Eagle Tree readings.

Under the relatively high loads that result in powering this size of heli, the nominal voltage of a good Lipo pack will stay around 3.7V per cell, and the curent high C packs yield more like 3.8V/cell. On the other hand, the A123 cells would drop down to 2.8 or 2.9V per cell.

So for more realistic comparisons, a modern 5 cell Lipo will easily deliver 19.5 volts (3.8 x 5), the A123 would require more like 7 cells (2.8 x 7 = 19.6). And when you consider the relatively high weight of the 7 cell A123 packs when compared to a 5S Lipo, it did not take long for me and others to stop using them. And now, considering the current costs of decent lipos, relative to back when we tried A123's, I do not think that even the cost savings warrant using them.

The A123 packs do work, but for me, I cannot see any reason to go to them.
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Old Feb 22, 2013, 08:27 PM
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I see Century discontinued the RTF and Plug & Play Swift helis .... and a bunch of motors, and a bunch of ESCs. I hope the NX isn't next ... Are they moving away from large electrics and just focusing on larger gas helis and quads/multi-rotors ?
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Old Feb 23, 2013, 08:39 PM
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Quote:
Originally Posted by FR4-Pilot View Post
I see Century discontinued the RTF and Plug & Play Swift helis .... and a bunch of motors, and a bunch of ESCs. I hope the NX isn't next ... Are they moving away from large electrics and just focusing on larger gas helis and quads/multi-rotors ?
I don't think so as their new Radikal E640 seems to be well received and many of us with one are asking for a 550 version of it now on some forums (e.g the Century forums on HeliFreaks.

I was glad to hear of the discontinuation of the Swift RTF because I think it was a failure on the market, simply because the electronics it came with sucked big time. The heli itself was OK but I found the servos, gyro and TX were POS's.

Now that they have sold out of the Swift 16 RTF, they can nowl consider doing the Swift NX in an RX ready version with some decent servos and a decent gyro. Then they might get more people into it. The biggest reason for Align's success in the 550 market is because they put it on the market in an RX ready package with decent digital servos and a decent gyro.
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Old Feb 24, 2013, 08:54 PM
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It looks like there is very little difference between the Swift 550 carbon and the Swift 620,even the frames look very nearly identical. Is the 600 frame really the same size as the 550's?

What parts are different between the two?
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Old Feb 24, 2013, 09:23 PM
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1300 RPM test flights today. 286 Watts for hovering. 258 Watts for forward flight

This is proving to be quite a versatile setup - I haven't even flown this heli at head speeds over 1600 yet - and all I'll have to do is change the throttle curve. This is great!

Century Swift 16 - Flight #10 - 1300 RPM Hover (5 min 21 sec)


Century Swift 16 - Flight #11 - 1300 RPM Forward Flight (5 min 19 sec)


I've updated post 6791 with the results of today's flights. Awesome day for flying too

-John
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Old Feb 24, 2013, 09:30 PM
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Quote:
Originally Posted by Atomic Skull View Post
It looks like there is very little difference between the Swift 550 carbon and the Swift 620,even the frames look very nearly identical. Is the 600 frame really the same size as the 550's?

What parts are different between the two?
The 620's frame has a larger opening for the gears (among other differences) - this allows a double stack for the main gear if running with a pack larger than 6S (the longer pinion would then be needed). The boom is longer, obviously on the 620, and it uses the metal tail case, which has since been discontinued (makes me sad). The 620 has all metal head and tail, where the 550 carbon is only partially metal.

If you download the manuals for both you can compare and see the details and differences more clearly. Many of the parts are similar however.
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Old Feb 24, 2013, 10:03 PM
If I build it, it will fly
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Wow, on the forward flight you could have gone what? 10min? Impressive.

~psguardian
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Old Feb 24, 2013, 10:11 PM
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The calcs are indicating around 9 minutes - I might just test that and see

Tomorrow my asymmetrical 550mm blades should arrive. I want to see if I really can double my (upright) flight times as advertised by SpinBlades .... or lower the head speed even more ...
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Old Feb 24, 2013, 10:24 PM
If I build it, it will fly
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I would think the advertised increase in flight time would come from lowered headspeed. I'm eagerly awaiting your delivery now LoL.

~psguardian
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Old Feb 24, 2013, 10:31 PM
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It's going to be interesting for sure

From what I've read, the blades create lift at lower angles of attack (even at 0), which means less drag placed on the power system for a given amount of lift, which would require less current, so longer flight (it seems anyway). I may have to adjust my above-mid-stick pitch curve to coincide with blades that have 2x (or whatever) lift. Who knows, maybe a combo of both (lower RPM & increased lift) is possible ?

I have to be careful though, as head speed slows so does the tail rotor, and if I slow it too much, then add blades with extra lift (extra torque) the tail may not be able to keep up since it will be spinning slower. I'll have to put my largest tail blades on if I go down that path ... or get larger ones.
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Old Feb 24, 2013, 11:04 PM
If I build it, it will fly
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Since these blades are suppose to generate lift at 0 pitch you should get light on the skids at mid stick & lift off sooner pitch wise, at your current settings. I would say keep the throttle curve where it is, but reduce the pitch curve above mid stick.

~psguardian
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Old Feb 24, 2013, 11:13 PM
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Sounds like a plan ! I think if I want to go lower on the head speed then it's time to go down a tooth on the pinion - I noticed some bogging of the motor at 1300 (at times), so I'm probably at/near the cutoff for the 12T pinion.

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Old Feb 24, 2013, 11:25 PM
If I build it, it will fly
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Is your rudder at 85% rate? (I think that's what I heard?) I think the only way you could go lower is if you can you bump it up to 100%. If it's already there you could add some negative expo to make it quicker, or bump up the gyro maybe.

~psguardian
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