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Old Dec 28, 2012, 09:11 AM
The wheels touch down FIRST??
BJ64's Avatar
Australia, VIC, Melbourne
Joined Jun 2009
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Not an expert on Neu's ... or gearboxes either...

But woth a 14x10 on it, that thing should pull like a Bull in Springtime.

Maybe drop to a 12x6 for reference... or go a 4S.

Even though you've got an Ice 100A in it, before you go 4S, what amps is it actually pulling on that big prop on 3S?

All my testing so far has shown roughly DOUBLE the thrust and around 10-15 amps more going from 3S to 4S - so check what amps it's pulling on 3S before you even think about going 4S on a 14x10. A 14x9 on mine went like stink on 4S, but really yanked some fierce amps through the ESC (and ended up smoking the motor in it at the time - a HK S3).

A 100A Speedie should be able to handle it - hopefully your motor can too. Do you have a WattMeter?

BJ

PS - forgot to mention the KRP is another avid builder/overclocker of these things, NCR
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Old Dec 28, 2012, 10:07 AM
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Evan D's Avatar
Charlotte, NC
Joined Jan 2004
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That motor and gear box on 4S with a 13x13 is awesome, I don't see why the 14x10 wouldn't work well too. Make sure you have a good ESC hooked to it though...

Quote:
Originally Posted by xrx1113 View Post
Im running the neu 1110/1y.6.7:1 gearbox with a 14x10 prop on 3 cells with an ice 100.

It has unlimited vertical but its not very fast does anyone know how to fix this. IE: should I be running a smaller prop or should I go to 4 cells or both?
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Old Dec 28, 2012, 10:15 AM
I'm Addicted Already
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Tim,
Tower Hobbies says that the Ammo you are running maxes out at 592 watts. How are you running over 900?
Man, those Neus are pricey. Decisions, decisions.
At least I know a 40 mm spinner is the correct size and not the 35mm like TH refers to.
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Old Dec 28, 2012, 12:04 PM
Tim Lampe; Hobbico R&D
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Champaign, IL
Joined Dec 2009
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Quote:
Originally Posted by NCRealEstateGuy View Post
Tim,
Tower Hobbies says that the Ammo you are running maxes out at 592 watts. How are you running over 900?
Man, those Neus are pricey. Decisions, decisions.
At least I know a 40 mm spinner is the correct size and not the 35mm like TH refers to.
The ratings for the 28-45-3600 Ammo are 40A constant current, 70A surge current and 592 Watts continuous.

If you look at the in-flight data I posted in my blog you'll see I stated 65A, 950W in-flight at full-throttle. The 65A is below the 70A surge current specified for the motor. I use full-throttle only in brief bursts - like maybe ten seconds, maybe fifteen at most. Then lots of coasting (or floating).

If you look at some recent posts I made in the Siren thread you'll see more duscussion about numbers and such including a graph from data logging:

http://www.rcgroups.com/forums/showp...postcount=1601

I'm not sure why the descrepancy between the 65A I quoted in my blog vs. the 53A in an in-flight data log below. Probably the point-in-time during the flight - battery Voltage was lower?

I'm loving the Ammo/GP gearbox in my Siren, but I run lots of Neu motors in my other stuff - pylon racers. They are dear, but first-class quality that can be run hard. They have quite the good reputation.


Tim
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Old Dec 28, 2012, 02:02 PM
I'm Addicted Already
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Hey Tim,
I read your blog again and it seems like your #s are kind of what I am shooting for. I have never had a gear box before. Is this the one that you use? http://www3.towerhobbies.com/cgi-bin...?&I=LXWVT4&P=7
How does it attach to the motor? Are there any other parts that I need for the complete package?
Am I right that the GB only changes the rpms and not the wattage?
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Old Dec 28, 2012, 06:14 PM
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Charlotte, NC
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It's like the transmission in your car, you still have the same horse power..
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Old Dec 28, 2012, 07:52 PM
I'm Addicted Already
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SO, why am I looking at inrunners and not an outrunner anyways, like I have in every other plane I own?
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Old Dec 28, 2012, 09:06 PM
The wheels touch down FIRST??
BJ64's Avatar
Australia, VIC, Melbourne
Joined Jun 2009
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...because outrunners that generate above 800 or so watts start to get too big in diameter to fit down into the quite tight nose-space in a Siren.

A 35-36mm outrunner will just fit - remember, outrunners usually have the wiring coming out somewhere between the output shaft and the spinning motor can, so you have to get that wiring past the can and back to your ESC. Wires that touch the can when the motor is running don't tend to last all that long (ask me how I know ).

Inrunners, on the other hand, usually have the wiring coming out the back of the motor - so you can basically bung in an inrunner of bigger diameter (use up the space that the wiring had to have free when running out outrunner). And bigger diam/longer inrunners tend to mean more available power.

I have a couple of really nice, cheap-ish outrunners that would haul ass in my Siren - but they just won't fit. Or, if they do fit, I won't be able to keep the wiring far enough away from the motor can without feeding them outside the nose - which would look pretty bloody ugly.

My 2c...

BJ
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Old Dec 29, 2012, 05:43 AM
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Australia, QLD, Beaudesert
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Hi guys,
I test fitted all into the fuse today, and some other work.
Anyway if I fit threes as far up the snout as it goes I get a c of g at 77mm if I put the fours in It I end up at 78mm, Whats the go, should I add a bit of lead up front and go for 70mm?
Neal
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Last edited by neale; Dec 29, 2012 at 07:11 AM.
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Old Dec 29, 2012, 09:50 AM
Tim Lampe; Hobbico R&D
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Champaign, IL
Joined Dec 2009
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Quote:
Originally Posted by NCRealEstateGuy View Post
Hey Tim,
I read your blog again and it seems like your #s are kind of what I am shooting for. I have never had a gear box before. Is this the one that you use? http://www3.towerhobbies.com/cgi-bin...?&I=LXWVT4&P=7
How does it attach to the motor? Are there any other parts that I need for the complete package?
Am I right that the GB only changes the rpms and not the wattage?
Yes, the gear box in your link is the one I use - Great Planes 4.3:1.

It consists of basically three parts (not including the gears and shaft). The base unscrews from the center "can" (the black part in the image). The base attaches to the front of your motor with four screws (either included with the motor or inlcuded with the gear box). Once the base is attached to the motor, you then press the pinion gear onto the motor. Then, you screw on the main can to the base with a dab of threadlocker and you're good-to-go. It's all in the instructions that come with the gear box, but the instructions aren't posted on-line. Maybe I should do a little write up of my own with some images.

Tim
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Old Dec 29, 2012, 05:52 PM
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Australia, QLD, Beaudesert
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Hi Tim, hows it going?
I would, if you don't mind like your thoughts on c of g start point, I have spent a fair bit of time reading and looking thru threads for info on it.
I have read that people are running between 66 mm rite thru to 90 mm from L/E.
However 70 to 75mm seems to be the consensus, with towards 70mm being preferred.
With the gear I have used I am at 78mm whether I use a fours or threes 2200.
As I am very new to this I would like to be conservative to start with.
I am going to pick up some weights during the week, adding it to the nose and head for 70mm to 72mm. Is this a fair start point, or would a little further forward be the go.
I know different people different strokes, but just looking for a safe start point
Neal
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Old Dec 29, 2012, 09:24 PM
I'm Addicted Already
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From what I am finding out, I will probably maiden with a 70mm CG.
Neale, Are your motor and batts so light that even a 4 cell gets your CG at 78mm?
Thanks Tim for the GB breakdown. That makes sense. Now that I have your attention again, I have another question... even though your motor is rated fior much less Watts than what you fly at, is it not burining up because you only use short bursts of full throttle?
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Old Dec 29, 2012, 11:42 PM
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United States, FL, Lehigh Acres
Joined Aug 2011
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You were right I went down to a 12x9.5 from a 15x7 and then went up to 4 cells. Now it moves! And I still have unlimited verticle. I think it getting 80 mph or close ot it . Thanks guys.
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Old Dec 30, 2012, 08:30 AM
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Australia, QLD, Beaudesert
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NCRealaestateGuy.
The motor and box are light, and the 3s go rite up behind the box and motor, and I am comming out at 78mm.With 4s the batt will not sit as far forward and I am comming out at about 77mm, so I will need to add a little weight up front, though I dont think the extra weight is going to bother me all that much, the motor and box I am running is lite, if I was running a heavier motor it would not be an issue, so I spose it is a trade off! The esc I have is fairly chunky so that does not help, but at the end of the day the plane has come out lite, so a bit extra wont worry me. Some one else can correct me if I am wrong but, yes the motor can be run at much higher watts and survive IF it is not run flat out till it cooks it self, yes short run time = happy motor!
Neal.
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Old Dec 30, 2012, 09:04 AM
I'm Addicted Already
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Joined Feb 2011
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Neale,
Refresh us with the motor that you are running. Do you know the weight? I want to compare it to the Ammo 28 that I am leaning towards. If it weighs same as yours, then I might go up to a heavier motor. Why not just go up to a bigger motor and not add dead weight?
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