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Old Oct 16, 2006, 12:39 AM
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Jurgen Heilig's Avatar
53859 Niederkassel, Germany
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Quote:
Originally Posted by resedaguy
...
what is the hi-tec equivilent for multiplex for nanoS and tiny-s?
Nano-S = Hitec HS-55
Tiny-S = Hitec HS-81

The HS-65 is a perfect replacement for the HS-55.

Jürgen
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Old Oct 16, 2006, 12:56 AM
Hold my beer and watch this!
Jeremy Z's Avatar
Northern IL
Joined Oct 2005
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Random thought: I was curious a while ago why Multiplex would recommend the Himax motor over their "local" Hacker. If what Beagle says is true, and that the Himax is more efficient, that would explain it.

Do you have any insight on this, Jürgen?
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Old Oct 16, 2006, 01:24 AM
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Quote:
Originally Posted by Jeremy Z
Random thought: I was curious a while ago why Multiplex would recommend the Himax motor over their "local" Hacker. If what Beagle says is true, and that the Himax is more efficient, that would explain it.

Do you have any insight on this, Jürgen?
Multiplex is a "global player" and they already have Himax motors in their product line. Most likely they just put a package together which works well, and isn't too expensive. If I wanted something better, I would go for a Kontronik JAZZ and a KORA.

Jürgen
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Old Oct 16, 2006, 01:35 AM
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flieslikeabeagle's Avatar
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Quote:
Originally Posted by Vantasstic
I'm going the 'standard' route. Himax 3516-1130, APC 11x5.5E, CC45 ESC with UBEC, (probably) 3S 3200 Impulse LiPo. I haven't totally decided on the servos yet. Most likely HS-81s for the tail feathers. Maybe the same for the ailerons, but other's have talked about the HS-65s.
I'm sure it will be an excellent set-up. From the simulations I've run, Multiplex did their homework on this model. All the numbers I've calculated say the same thing: the recommended power system is an excellent choice. (I'm a bit shocked - Multiplex finally stops trying to power everything with a twenty-cent, ferrite-magnet, brushed, direct-drive, Speed 400 motor and a NiCd battery! )
Quote:
Originally Posted by Vantasstic
I'm not a hard-core 3D'r or pattern guy. I'm just a simple sports flier. I got the plane since it sounded like a good sport plane that can do some good aerobatics too.
IMHO, sports flying is where the most fun lies. Probably the best way to take the fun out of something and make it hard work is to either take it too seriously, or to turn it into a competition!
Quote:
Originally Posted by Vantasstic
I've also got a Multiplex Twin Star I'm working on now with two AXI 2212-26 motors and MTroniks 18amp ESCs.
I'd be interested to see if you end up having to move the CG forward. I re-read the stability chapter in Martin Simons "model aerodynamics" recently, and found out why my TS-II needed the CG more forward than a stock one: it seems that big propellers have the same (yaw) destabilizing effect as lots of front fuselage side area. So those of us using big props with outrunners will likely need to either move the CG forward of Multiplex' recommendation, or make the vertical stab bigger.
Quote:
Originally Posted by Vantasstic
I'm not one of those aforementioned "Multiplex religious people".
I didn't think you had that particular religion, I've never read anything you posted that showed symptoms of it.
Quote:
Originally Posted by Vantasstic
I got my stuff on sale and have an apparent inability to talk myself out of buying more planes that I really need.
Heh, too many of us have that disease, myself included!
Quote:
Originally Posted by Vantasstic
I did have a Micro Jet and didn't care for it due to the (un)launchability without a high power motor system...so not ALL Multiplex stuff is good.
See? You clearly don't have Multiplex religion, you are able to see flaws where they exist.
Quote:
Originally Posted by Vantasstic
There, if that doesn't tell you I just "Can't Say No" then I don't know what will.
. Very nice collection, though!

Events are conspiring to break down any remaining resistance I have to the Acromaster - first, my wife has been encouraging me to go get one.
Second, I realized I already have four 3S, 15C, 1350 mAh lipo packs: I can parallel two of them to make a 15C, 2700 mAh 3S2P pack capable of supplying 40 amps continuous current, just right for the Acromaster, and I'll have two more on hand for a second flight, all without spending a single dollar. That, of course, is presuming I can find a way to fit both packs into the fuse.

I saved the best for last: I just found out that I got an overtime check in the mail yesterday, for some extra hours I put in at work the last eight weeks. So now I have a couple of hundred bucks that I had forgotten I had coming. The accountants at my workplace work in weird and wonderful ways, and I never know what to expect next. I can't tell if that's general incompetence, or intended to keep us employees confused about what is due to us!

Anyhow, I'll drop by the LHS tomorrow. If they still have the lone Acromaster they had in stock last Friday (the one I checked out in the store), I think I'm gonna buy it.

-Flieslikeabeagle
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Old Oct 16, 2006, 01:50 AM
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flieslikeabeagle's Avatar
Los Angeles
Joined May 2004
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Quote:
Originally Posted by Jeremy Z
Random thought: I was curious a while ago why Multiplex would recommend the Himax motor over their "local" Hacker.
If the published motor constants are correct, the Himax is a tiny bit more efficient than the Hacker. Perhaps more importantly, it's rated to 48 amps max current for 15 seconds (from the Aeromicro website), while the smaller, lighter Hacker is only rated to 33 amps max (also for 15 seconds).

Hacker motors have a (well earned) reputation for handling more power than the published specs, but I expect Multiplex would prefer the extra safety margin provided by the heavier motor with the slightly higher current rating - if someone is abusive with the throttle, the Hacker will probably cook to death sooner than the Himax.

As Mike Mayberry (and others ??) has/have already shown, in the real world the Hacker does a fine job of flying the Acromaster.

I'm curious why Multiplex didn't recommend their own BL-480-4G geared 4.4:1 (with a 13x8 APC E on 3S lipo), which I think is a slightly better choice for the Acromaster than the recommended Himax - provided you don't hate a bit of gearbox noise. Perhaps it is because the Multiplex motor costs more than the Himax, or perhaps those Multiplex motors are now out of production? I still see them for sale at several vendors in the USA.

-Flieslikeabeagle
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Old Oct 16, 2006, 06:34 AM
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punkindrublik's Avatar
United States, CA, North Highlands
Joined Sep 2004
8,950 Posts
Quote:
Originally Posted by flieslikeabeagl
Sorry, Brian. I was trying to be helpful, honest!
No need to apologize, I was sincere when I said I appreciate the info

Thanks

Brian
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Old Oct 16, 2006, 10:58 AM
edible_engine's Avatar
Just south of Cambridge, UK
Joined Oct 2003
982 Posts
A30M is a good motor for it on a 13x6.5, any smaller a prop will be boring. id reccomend the A30L, possibly on 4S, for it, much better! both will mont perfect on the motor mount without adjusting it
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Old Oct 16, 2006, 12:44 PM
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Jurgen Heilig's Avatar
53859 Niederkassel, Germany
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Quote:
Originally Posted by flieslikeabeagl
...
But when I started to measure and calculate the performance of outrunners vs inrunners, I found disturbing results. The most disturbing are that most of the time, the outrunner is considerably heavier, and considerably less efficient than an equally powerful inrunner.
...
As I mentioned, for equal power handling ability, an outrunner motor is usually much heavier than an inrunner.
...
-Flieslikeabeagle
What gave you the idea, that outrunners are considerably heavier? If you take the inrunners from Hacker or Kontronik and compare them with their outrunner counterparts, it is usually quite the opposite (last but not least because of the necessary gearbox).

While inrunners usually have a slight edge on efficiency, the advantage is often gone once you take the gearbox losses into account.

Jürgen
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Old Oct 16, 2006, 12:51 PM
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Quote:
Originally Posted by flieslikeabeagl
I was just looking at motor constants and other data for the Himax, Power 10, and the Multiplex BL-480-4G (inrunner, geared 4.4:1). The results are interesting.
...
The weights of the Himax and Multiplex motors are not too different - with the metal gearbox, the inrunner has only a half-ounce weight advantage.
...
-Flieslikeabeagle
The Himax C3516-1130 weighs 134g, the Multiplex BL-480-4G weighs 165g. Where do you see a half-ounce weight advantage for the geared inrunner?

I see a weight advantage of more than 1oz for the outrunner.

Jürgen
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Old Oct 16, 2006, 01:01 PM
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Quote:
Originally Posted by flieslikeabeagl
...
For those who don't like equations, I have attached plots showing the calculated efficiency curves for the Multiplex BL480-4, the Himax 3516-1130, and the Eflite Power 10.

Note that in real life, both the ESC and the battery itself have some internal resistance, which should be added to Rm to get the real-world efficiency curve. The attached graphs do not include these effects, and therefore allow you to compare all three motors without being confused by the effects of different speed controls or batteries.

-Flieslikeabeagle
Your calculated curve for the BL-480-4G shows an efficiency of up to 87%.

Please note, that Multiplex claims a maximum efficiency of 83% for the motor, and Maxon (the manufacturer of the gearbox) claims a maximum efficiency of 84% for their planetary 22mm gearbox. Combined, you only get 70% under ideal conditions.

http://www.maxonmotor.com/ch/en/gear.asp

Jürgen
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Old Oct 16, 2006, 01:10 PM
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Quote:
Originally Posted by flieslikeabeagl
...
I'm curious why Multiplex didn't recommend their own BL-480-4G geared 4.4:1 (with a 13x8 APC E on 3S lipo), which I think is a slightly better choice for the Acromaster than the recommended Himax - provided you don't hate a bit of gearbox noise.
...
-Flieslikeabeagle
I think I have answered the question in my previous posts, but lets summarize:

1. The Himax weighs less than the BL-480-4G.
2. The Himax has a 5mm shaft, which is much stronger than a 4mm shaft.
3. In case of a mishap, you can easily change the shaft of an outrunner.
4. The Maxon gearbox was never designed to take the gyroscopic loads of a fixed prop doing 3D aerobatics.
4. The Himax is more efficient, runs cooler, and a lot quieter.
5. A direct drive is more dynamic than a geared drive (it has a much wider speed range).
6. The MPX list price of the Himax is less than half of the BL-480-4G.

Jürgen
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Old Oct 16, 2006, 01:19 PM
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Quote:
Originally Posted by edible_engine
A30M is a good motor for it on a 13x6.5, any smaller a prop will be boring.
A 13x6.5 on the A30-16M will push it far over its maximum specified current. I would not recommend this.
Quote:
Originally Posted by edible_engine
id reccomend the A30L, possibly on 4S, for it, much better!
The A30-12L will only spin about an 8" or 9" prop on 4S lipo. The small prop will be very inefficient.

Tdab (post #715) listed some impressive numbers for the Hacker A30-16M: nearly 400 watts power from a (very good, low resistance) 3S lipo pack with the 11x5.5 APC E prop. That really should be plenty of power for a 1kg plane, for all but the most hardcore power junkies.

As far as I can see, only the largest of the Hacker 30 series motors, the A30-12XL, has a Kv low enough to be run on a 4S lipo pack with a reasonably large prop. This motor will handle a 13" prop on a 3S lipo pack (some people abuse it with a 14x7), and probably a 11" or 12" prop on a 4S lipo pack. However, this is a considerably heavier motor (about 45 grams heavier, I estimate).

The Multiplex BL-480-4G (with the 4.4:1 gearbox) also has a low enough Kv to be run on a 4S lipo pack.

-Flieslikeabeagle
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Old Oct 16, 2006, 01:28 PM
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Quote:
Originally Posted by flieslikeabeagl
...
The Multiplex BL-480-4G (with the 4.4:1 gearbox) also has a low enough Kv to be run on a 4S lipo pack.

-Flieslikeabeagle
Running a 3250kV motor on approx. 14V = 45.500 (motor)rpm

Have a look at the homepage of the gearbox manufacturer: Recommended input rpm is <8000 rpm.

Have you ever used a planetary gearbox on a high power motor? While it is Ok do run such a unit in a glider for short bursts of a couple of seconds, it heats up rapidly, when used in a sports/aerobatic model.

The Acro-Lift from Simprop is a typical example of such a model, and the motor needs additional heat sinks.

Jürgen
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Old Oct 16, 2006, 02:01 PM
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servo extension size?

I need to buy servo extensions. The book does not say what size? 6inch? 12in?
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Old Oct 16, 2006, 02:14 PM
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Quote:
Originally Posted by resedaguy
I need to buy servo extensions. The book does not say what size? 6inch? 12in?
Most guys probably just cut the servo cables and extend them as required by soldering an extension in between.

Jürgen
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