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Old 10-10-2016, 10:57 AM   #1 (permalink)
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Default 450 with 2s lipo

Upon the suggestion of others I have just started using 2s lipo for my 450. Using TC @ 98 as a start did a brief hover . Tail authority is good. I have upsized tail blades when necessary. Will be experimenting with different TC and slowly increasing flying time to see how she reacts. Thanks to Nikki5 and others for their help.
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Old 10-10-2016, 02:23 PM   #2 (permalink)
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Look forward to how this turn out.... what size blades are you running?
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Old 10-10-2016, 03:32 PM   #3 (permalink)
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The blades are 325's that came with kit. Will see what she can do .
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Old 10-14-2016, 03:41 PM   #4 (permalink)
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First day of multiple hovers using 2s lipo with 450 .
Did 3 - 1 minute hovers today . Full pack read 8.36 at beginning and ended with lipo reading of 7.92. Head speed reading using helitach at beginning was 2117 and 2058 at end. No tail wagging or bobbing. Will start to do continuous flight to see how many seconds I can get past 3 minute mark for TC as it is now and then lower TC and start again.
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Old 10-19-2016, 02:19 PM   #5 (permalink)
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Currently at TC 0, 65,65,65,65. Flew two 1min 30 sec flights hover and ff. Full pack reading 8.36v ended at 8.00v. Motor slightly warm. HS unknown. Could not get reading from helitach. No tail wagging or bobbing.
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Old 10-25-2016, 01:35 PM   #6 (permalink)
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Subscribed. I may have to pick up some 2S packs to try out just for grins. I've been playing with a Blade 180CFX on 2S and it works great. Dropping from 3S to 2S really helps tame that wicked little beast!

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Old 10-25-2016, 01:57 PM   #7 (permalink)
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Interesting. So this is to tame it down instead of just running a lower TC on 3s plus dual rates??

Imagine 2s will tame it way down like a gearing change+lower TC+dual rates???

Interested to see what kind of performance and flight time you get. Tried 3s in my 6s 450 to see if I could get some long low hs flights but it could barely lift off the ground. ..lol

Thought about trying 4s but just ran a low TC since my esc has active freewheeling and learned that I don't like low hs anyway but always find new experiments interesting.

Once in a while you find something everyone says will never work that ends up working great
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Old 10-25-2016, 06:11 PM   #8 (permalink)
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The 180CFX has been a relatively easy 2S conversion for me. On the 450 it may or may not be as easy. I don't know yet. Only dropping the TC using 3S means something has to absorb the heat from running at part throttle all the time and that will be the ESC. Also you'll never find a pinion small enough to be able to run the 3S motor efficiently at 2S RPM using a 3S pack. I've cooked a few ESC's trying this. I always learn the hard way.

I've got a pile of Align and clone 450's that I was going to get rid of. They could now become 2S test mules as I don't care if they crash and I have a mess of parts for them. If it all works out I may convert some of my beloved Beam 450's to 2S. Due to my thumb physical limitations high performance and 3D are the LAST thing I'm concerned about. 2S sounds real good to me.

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Old 10-26-2016, 11:00 AM   #9 (permalink)
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Quote:
Originally Posted by Turbojoe View Post
Only dropping the TC using 3S means something has to absorb the heat from running at part throttle all the time and that will be the ESC. Also you'll never find a pinion small enough to be able to run the 3S motor efficiently at 2S RPM using a 3S pack. I've cooked a few ESC's trying this. I always learn the hard way.
In my experience, it totally depends on the ESC. I routinely run the Oxy+/Eox on 4s at an FBL-governed HS that is equivalent to 40% throttle. I took it down to 35% quite a few times during initial testing. The HW50A (v3 so no AFW) does not even get warm. Absolutely no issues. Flight times are also on par with what folks get with theoretically more efficient set-ups.

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Old 10-26-2016, 12:48 PM   #10 (permalink)
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In my experience, it totally depends on the ESC. I routinely run the Oxy+/Eox on 4s at an FBL-governed HS that is equivalent to 40% throttle. I took it down to 35% quite a few times during initial testing. The HW50A (v3 so no AFW) does not even get warm. Absolutely no issues. Flight times are also on par with what folks get with theoretically more efficient set-ups.

Very interesting information you posted. Wonder if my statement on stopping at 60% TC might be re-evaluated . With my plans not to push helicopter might be able to lower TC . Did 4 minute flight today. Motor slightly warm and nothing significant on ESC.
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Old 10-29-2016, 03:13 AM   #11 (permalink)
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Funny subject I've gotten 7 minutes (before the low voltage took over yes over discharged) on a 6 s setup with low throttle curve and flying smooth 3D but can get 5 minutes easy
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Old 10-29-2016, 03:29 AM   #12 (permalink)
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Funny subject I've gotten 7 minutes (before the low voltage took over yes over discharged) on a 6 s setup with low throttle curve and flying smooth 3D but can get 5 minutes easy
^^Similar to my experience.
Personally I'm sure what the objective of all this low cell count / very low headspeed stuff is? Is the idea just to hover for the maximum time possible?.. Sounds extremely boring if so.

If all you want to do is hover for ages connect a long wire to the heli and a big old RV battery on the ground... you could hover all day.
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Old 10-29-2016, 01:47 PM   #13 (permalink)
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If it all works out I may convert some of my beloved Beam 450's to 2S. Due to my thumb physical limitations high performance and 3D are the LAST thing I'm concerned about. 2S sounds real good to me.

Joe
I have two Beam 450s, one flybarred and one FBL and they both need to run pretty much flat-out for any aerobatic flying. (both are 3s and I think the headspeed is around 3000 and it just seems to require that kind of hs for them to work properly for me)

When I was flying a Trex 450 I used to get about 8 minutes of gentle circuits just by running a lower throttle curve on 3s.
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Old 02-07-2017, 01:48 PM   #14 (permalink)
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Alright so I'm going to kick this thread in the shins again by posing a question. Somewhere on this forum I read that running a motor/ESC at less than 85% would excessively heat the ESC. The theory was that the ESC has to work harder and heats up more below 85% and above that works less to pass the current to the motor. Not sure I subscribe to that theory. To me, simple physics says more current = more heat both in the ESC and motor. Lower current = less heat. The ESC just regulates the amount of current by the frequency it switches on and off. Am I wrong? I always spec my ESC's at least 25% to 30% more than the max rated motor current anyway.

While I have over 40 RC aircraft and all kinds, last week I flew a heli for the first time. My heli fleet includes a Blade 450 3D, Trex 500, Clone HK 500 and a Compass 7HVU. One of the 500's (probably the clone) is getting an A109 fuselage with Copter-X 4-blade floating head and scale CF blades. Also have an MD500E fuselage but haven't decided what to do with that one yet. My goal with these helis overall is just sport and scale flying. At least for now.

The 450 is my test and training heli. Got it used (abused) and rebuilt the whole thing. Spent some time getting the gyro gain figured out for my Futaba 7C which seems pretty good at 52%. Anything much higher produces tail wag.

The motor is the stock E-flite 420 3800kv, 10T pinion. Battery is 3S and even at 85% the head-speed seems pretty hot. Managed to hover with 30% expo but did set it down a little hard once contacting the tail blades which snapped an arm on the pitch slider. Didn't realize the tail guard had been ground off and was a bit shorter than it should have been. Upgraded to an aluminum slider and some other parts which are about to go on.

The gyroscopic action was pretty strong because of the HS so I'm swapping the motor for an Align 400 2800kv to see where that puts the HS. I'll use a tach to check it before making the changes so there's no guessing as to the results and what throttle % produces what HS. Hopefully I'll end up with a more docile trainer with longer flight time.

A 15T pinion on the Trex raises another question. Since it has 33% more teeth than a 10T does, would that equate to a 33% difference in HS? I read about swapping pinions all the time but don't recall anyone actually applying the math to it.

On the 500's the plan is 4S and a smaller pinion at least with the 4-blade head. A few Compass pilots have been running their 12S helis on 6S with great results. That's my plan with that one as well. Reports are they are very smooth fliers that will still do less intensive aerobatics. Longer flight time is always a bonus in my book.

Last edited by XionUAV; 02-07-2017 at 02:04 PM.. Reason: Updated Info
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Old 02-07-2017, 08:30 PM   #15 (permalink)
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Alright so I'm going to kick this thread in the shins again by posing a question. Somewhere on this forum I read that running a motor/ESC at less than 85% would excessively heat the ESC. The theory was that the ESC has to work harder and heats up more below 85% and above that works less to pass the current to the motor. Not sure I subscribe to that theory. To me, simple physics says more current = more heat both in the ESC and motor. Lower current = less heat. The ESC just regulates the amount of current by the frequency it switches on and off. Am I wrong? I always spec my ESC's at least 25% to 30% more than the max rated motor current anyway.
Yes, you're wrong. The ESC works the least when the throttle is wide open and the most when the throttle is extremely low. Think of it like this, wide open the ESC is just passing current through to the motor. At low speed the ESC is quickly pulsing the power and removing most of it. It's more complex than that, but that's generally the idea. ESC's with active freewheeling are able to run much cooler at lower speeds. I run mine below 50% routinely without overheating it. Having said that, correct gearing and lowered input voltage is a better way to do low head speed if you don't intend to run both low and high head speed in the same flight.

Good luck with your LHS setups.
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Old 02-07-2017, 09:15 PM   #16 (permalink)
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(thinking of something else. where is the delete button?)
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Old 02-07-2017, 09:52 PM   #17 (permalink)
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Sorry, rereading that it sounds pretty harsh.

Been thinking about your pinion question. Let's say the main gear has 150teeth and you use a 15t pinion, the gear ratio is 10:1. So if the motor turns 30,000rpm your rotor rpm would be 3000. Changing to a 10t pinion makes the gear ratio 15:1 and the rotor rpm at the same motor speed 2000rpm. So, it would seem that you're correct and the ratio of rotor speed change equals the ratio of pinion teeth change.

Of course, it's been a long time since my last math class...
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Old 02-07-2017, 09:54 PM   #18 (permalink)
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Yep. Seems the switching action of the FET's at lower throttle settings generates more heat than the current going through them when they aren't switching as much at higher throttle settings. Interesting. From a Greg Covey article, just in case someone else is interested-

"One of the paradoxes of brushless motor controllers is that partial throttle operation actually generates more ESC heat than full throttle operation. FETS have a very small resistance when they are fully "on" and current is flowing through them. This generates a relatively small amount of heat but it is not a significant amount. As always, there's more to it. FETs don't just go from an ON to an OFF state, there is a bit of a ramp to the process, a period where the FET is neither open nor closed. Electricity can flow through the FET during these periods, but the resistance in the FET is much higher than when the FET is fully ON. This leakage across a high resistance generates a significant amount of heat. At partial throttle, the FETs are required to cycle much more rapidly than at full throttle, so a great deal more heat is generated at partial throttle than at full throttle. Similarly, more heat is generated in controllers set to run at high switching rates than those set to run at lower switching rates."
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Old 02-08-2017, 11:07 AM   #19 (permalink)
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When playing with tooth counts, just be careful with the numbers! A 15t pinion has 50% more teeth than a 10t, and the same 10t has 33% less than that 15t. You get the correct RPM answer going either way, as long as you use the correct percentage: 2,000 + 50%(2,000) = 3,000 and 3,000 - 33%(3,000) = 2,000.

Also, it really does make a difference which ESC you are using for what application. The HW50A is total overkill for the Oxy, but not too heavy and fits fine. With 4s on 11t and relatively low HS, mine is routinely working at 40%, but it barely gets warm. If I had it in a G380 at 40%, it probably wouldn't like me.
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Old 02-09-2017, 10:56 AM   #20 (permalink)
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Quote:
Originally Posted by XionUAV View Post
Alright so I'm going to kick this thread in the shins again by posing a question. Somewhere on this forum I read that running a motor/ESC at less than 85% would excessively heat the ESC. The theory was that the ESC has to work harder and heats up more below 85% and above that works less to pass the current to the motor. Not sure I subscribe to that theory. To me, simple physics says more current = more heat both in the ESC and motor. Lower current = less heat. The ESC just regulates the amount of current by the frequency it switches on and off. Am I wrong? I always spec my ESC's at least 25% to 30% more than the max rated motor current anyway.

While I have over 40 RC aircraft and all kinds, last week I flew a heli for the first time. My heli fleet includes a Blade 450 3D, Trex 500, Clone HK 500 and a Compass 7HVU. One of the 500's (probably the clone) is getting an A109 fuselage with Copter-X 4-blade floating head and scale CF blades. Also have an MD500E fuselage but haven't decided what to do with that one yet. My goal with these helis overall is just sport and scale flying. At least for now.

The 450 is my test and training heli. Got it used (abused) and rebuilt the whole thing. Spent some time getting the gyro gain figured out for my Futaba 7C which seems pretty good at 52%. Anything much higher produces tail wag.

The motor is the stock E-flite 420 3800kv, 10T pinion. Battery is 3S and even at 85% the head-speed seems pretty hot. Managed to hover with 30% expo but did set it down a little hard once contacting the tail blades which snapped an arm on the pitch slider. Didn't realize the tail guard had been ground off and was a bit shorter than it should have been. Upgraded to an aluminum slider and some other parts which are about to go on.

The gyroscopic action was pretty strong because of the HS so I'm swapping the motor for an Align 400 2800kv to see where that puts the HS. I'll use a tach to check it before making the changes so there's no guessing as to the results and what throttle % produces what HS. Hopefully I'll end up with a more docile trainer with longer flight time.

A 15T pinion on the Trex raises another question. Since it has 33% more teeth than a 10T does, would that equate to a 33% difference in HS? I read about swapping pinions all the time but don't recall anyone actually applying the math to it.

On the 500's the plan is 4S and a smaller pinion at least with the 4-blade head. A few Compass pilots have been running their 12S helis on 6S with great results. That's my plan with that one as well. Reports are they are very smooth fliers that will still do less intensive aerobatics. Longer flight time is always a bonus in my book.
I'm finishing up 500 on 4s with 2-blade head . Looking forward to maiden
in spring.

Good luck with your 500 project.
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