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Logo 500 › Advice: Gearing and setup for Sport/3D trainer
02-21-2013 04:09 PM  5 years agoPost 1
darkfa8

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Brick, NJ - USA

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I just took ownership of a mostly complete L600 with BennyTRD FBL head. I'm planning to convert it to swing 550 blades, but use a 600 boom with no supports.

I will be using a Scorpion HKIII-4020-890 motor with a 5mm shaft, 6s4100 45C packs, AR7200BX, MKS BLS or HBL servos, Gaui 100-amp ESC or equivalent. I will be running regular throttle curves.

The model currently has a mod 1 main gear, but I think I should change to the mod 7. I'm considering 1500-1750 head speeds.

I need this model to be my trainer for sport/mild 3D. I'm not looking to blow anyone's doors off.

I haven't selected blades yet, but I'm considering Spin asymmetricals.

Any pointers appreciated.

- Dan Goldstein
Team Revolectrix

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02-21-2013 07:28 PM  5 years agoPost 2
dahld

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Bakersfield, CA, USA

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I will assume you meant the Scorp 4020-"890", as they don't make a "990" (-:

You can't get to the low head speeds you're looking at on 6S with the mod 1.0 gears. You are correct in going to the mod .7 gears.

With Mod .7 gears and an 890kv motor on 6S, you'll need to go with possibly a 17 tooth. I haven't run the numbers on a calculator, but experience tells me this might be the case.

With the "classic" kv of 1100 on 6S with Mod .7 gears, the Logo 500 uses usually between 13-15 tooth pinions (depending on desired head speed). So with the lower kv of 890, you'll need larger pinions, say in the 17-19 tooth range.

If you are going to run the low head speeds noted, then a 4100mah capacity battery will give OK flight times. Bump the head speeds up to the more classic 3D speeds on the Logo 500 of say 2100-2300, and your flights will be too short (for most pilots).

Hope this helps,

(-: Dave

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02-21-2013 08:38 PM  5 years agoPost 3
darkfa8

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Brick, NJ - USA

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Dave,

Mr. Mel's head calc is telling me a 13t will give me ~1500 non-governed with the mod.7 main gear and my motor/45c 6s lipos.

- Dan Goldstein
Team Revolectrix

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02-21-2013 10:12 PM  5 years agoPost 4
RyanW

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Edmond, Oklahoma

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I have a Logo 500 with the similar function.

It is a 500SE with the larger 600 diameter tail boom, cut down to the 3D length. I run 523 and 553 blades on it.

The power set up is:

Jive 100+LV

Xera 1100kv (probably going to the Pyro soon, but no issues with the Xera)

Opti-Power 4300mAh 6S pack

17t Pinion w/ Mod 0.7 gears

I have three headspeeds- 1900/2100/2200

It flies absolutely beautifully with this set up! I can crank down the throttle curve to do something around 1600HS, but I don't leave it there. The motor is never as much as warm after a flight.

I am trying out some Rail 556 blades when the weather clears.

-Ryan
Mikado USA, Kontronik, Opti-Power, MKS Servos

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02-22-2013 12:25 AM  5 years agoPost 5
dahld

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Bakersfield, CA, USA

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@ darkfa8,

Well, it's hard to argue with Fredrick ...but here's my "old school" way of figuring things, tried, trued, and proven pretty accurate over time, before we had calculators:

Using an average voltage during flight on a 6S pack of 23V, times the motor's kv of 890, = 20470 motor rpm, divided by the gear ratio of 11.76 (153 tooth Mod.7 main gear and 13T pinion), = 1764 head speed... but you lose about 10% in inefficiency, so take 90% of 1764 = 1587 (full throttle head speed. Maybe this is where you got the ~1500 "non-governed" head speed figure). But, you want the ESC running at no more than about 80% of full throttle (so you have some head room to maintain that head speed under load, even if you are running throttle curves vs. a governor), so take 80% of 1587 = 1269. Too low.

The estimate I gave of using a 17T, when using the above calculation method, ends-up with a head speed of 1637, which is in the middle of the head speed range you wanted.

It's not a contest here to see who's right or wrong. I'm just thinking your figure of 1500 is without taking any "headroom" on the ESC into account.

Hope this helps, at least a little,

(-: Dave

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02-22-2013 01:16 AM  5 years agoPost 6
darkfa8

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Brick, NJ - USA

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Dave,

Thank you for the explanation of your methodolgy. My take based on experience with the ESC's that I was under the impression that keeping the ESC in a state that it is more frequently switching the MOSFETs to the ON position is more efficient that having them dwell in a OFF state for too long to maintain a commanded throttle percentage.

Now this theory originated from my involvement with Castle ESC operation. I presumed this was the case with other ESCs. I stay mindful of headroom and would intend to run a curve in the 90-85-90 range depending on how the head responds during flight. I keep mindful of this in my gearing to insure I'm not hammering the ESC, but am still getting the rough head speed I'm targetting.

I think I will try a few pinions and see what happens, it's just a bit costly given Mikado's parts pricing. I'm just trying to get as close to the right pinion with the math to minimize the quantity of pinion sizes I need to buy to get there.

- Dan Goldstein
Team Revolectrix

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02-22-2013 02:13 AM  5 years agoPost 7
RyanW

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Edmond, Oklahoma

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In the past, a lot of ESCs only did well at near full throttle applications. I personally have shelled a few by running them at low partial throttle (40~50%). That is what can really stress an inferior ESC. The Kontronik have always been very efficient at partial throttle and as Dave mentioned, you want the headroom. I believe Kontronik says to set up your machine so you have the desired head speed an no more than 80% throttle input to allow for the extra headspeed.

Don't take these numbers to use, as they change for every radio, but for example my throttle percentages are something like this:

65% = 2250
55% = 2100
45% = 1950

It runs super smooth and cool all of the time set up like this.

-Ryan

-Ryan
Mikado USA, Kontronik, Opti-Power, MKS Servos

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02-22-2013 02:20 AM  5 years agoPost 8
darkfa8

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Brick, NJ - USA

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Ryan,

That's interesting to know, but anything Kontronik or YGE is out of my budget, even used. I'll be running either a Gaui/Hobbywing 100-amp or Castle Talon 90.

- Dan Goldstein
Team Revolectrix

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02-23-2013 01:45 PM  5 years agoPost 9
v58 fuy

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UK - Kent

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I run a Kontronik so no real issues with using low throttle settings - but please bear in mind using a larger pinion than you really need for the head speed you are running is bad practice.

If you run a pinion which is bigger than you really need, and end up reaching the desired head speed at say 50 or 60%, this you may say sounds good because you have a lot of space for the governor to operate I.e. all the way from 50 or 60 up to 100 - great.

But in reality if you run such low throttle settings for the chosen head speed you have "over geared" your system, and will mean bogging will happen much easier, meaning the governor will work much harder maintaining your head speed.

As DHALD said, you should really aim for a pinion which will give your desired head speed at around 75/80% throttle setting - this will give the governor room, but also reduce the amount of work the system as to do, making things more efficient.

David

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02-24-2013 06:12 PM  5 years agoPost 10
Andy from Sandy

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Bedfordshire, UK

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I emailed Scorpion about the power output of the 4020-890 and was told the figures published are when it is run on 8S.

In this application with a 6S pack use the 4020-1100 as it will be more efficient.

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08-25-2013 03:24 AM  5 years agoPost 11
darkfa8

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Brick, NJ - USA

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An update:

The model flies well for basic aerobatics for 7-8 minutes. I havent tached the headspeed, but I am feeling a switch to the HKIII-4020-1000 would be optimal as othersnhave suggested. I was trying to make the 890 work since I had it on hand.

The truth is I'm trying to replicate the performance and flight times I was getting with my Gaui X5. I was spinning 2400 on the head and getting 6-7 minute flights with nearly no bogging. Granted the AUW on my X5 was a full pound lighter. My custom Logo 550 weightsin at 6lbs with the same electronics.

- Dan Goldstein
Team Revolectrix

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