pappy35

What's the basis of using, or not using, a motor with a gearbox? I imagine a gearbox allows a motor to run at a more efficient speed but then that would have to be balanced against the additional frictional losses in the gearbox itself. I never have been able to find any detailed info to be able to compare an inrunner/gbx vs. a low Kv outrunner.

can773

My Feedback: (1)

I will move my post from the other thread here



Hi Al,

I will try and help you with the motor question.

Basically, the real differences between outrunner and inrunner are maintenance and to a lesser extent efficiency. The outrunners in general need zero to very little maintenance. The only part that needs replacement as maintenance is bearings, which should last for many flights. Inrunners require gearbox greasing about every 50 or so flights. Inrunners are slightly more efficient (5% or so), but are louder in flight compared to an outrunner.

There are many more options for outrunners than inrunners, which gives you some very low cost options. Be cautious of the weight, the low cost outrunners can be very heavy. Typically the top of the line inrunners and outrunners weigh about 560-600g with all the prop adapters/mounts.

Mostly its a matter of preference, and if you are willing to accept a slightly heavier motor with a little less efficiency to avoid any maintenance work.

Hope that helps!

pappy35

That's great. I thought there my be some 'magic' to inrunners I was missing. I'm all for low/no maintenance solutions so I'll start digging around for an outrunner. I'm going to be getting an EF Vanquish (typical 2M/5Kg ship) and I've chosen batteries and ESC, now I'm looking at motor options.

KeithB

My Feedback: (1)

Pappy,

I think Chad's reply implied this, but I think it's worth pointing out that outrunners do pull more amps than inrunners. My observations are they pull 15% to 20% more amps (mid to high 70's for outrunners vs. low to mid 60's for an inrunner). This varies somewhat depending on the winds of the motor, but in matched power the inrunner will pull fewer amps. Considering the expense of batteries I personally like to treat my batteries as gently as possible so I prefer the inrunner.

It's true that the outrunner is less maintenance, but greasing gears is not really tough (not like bearings in a YS) and compared to a YS inrunners are still amazingly quite.

Really both have their pros and cons. One option you might look at is the Neu F3A motor, it's becoming fairly popular as an inrunner solution.

Keith B

pappy35

Batteries aren't expensive anymore:

ZIPPY Flightmax 5000mAh 5S1P 15C 578gr $42.95
ZIPPY Flightmax 5000mAh 5S1P 20C 586gr $55.70
ZIPPY Flightmax 5000mAh 5S1P 25C 628gr $66.08
ZIPPY Flightmax 5000mAh 5S1P 30C 650gr $54.85

Here's the ESC:
[link=http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=4691&Product_Name=TURNIGY_Sentilon100A_HV_5-12S_BESC_(Ver4)]Turnigy 100A ESC[/link] $99.99

I bought bunch of these (same brand different cell counts and capacities) this past spring as a test. I puposely abused them (hot charges, overdischarge, etc.) and so far after about ~25 on each they are holding up great. For, literally, a third the cost of 'name-brand' packs I don't see a downside.

Jeff Boyd 2

Ahhhhhhhh . . you're on the HobbyCity site ??

I would NOT leave Rhino packs out of the equation. Sure . . a little heavier, but damn good packs it seems

Although . . you are correct. The "Name" brands would be SERIOUSLY worried about this

JB

Jon Wold

A german magazine (perhaps it was Aufwind, I don't remember) had a comparison of inrunner to outrunner recently. Efficiency-wise it was rather inconclusive, and out of all the gear types the planetary gear was favoured because it does not offset the shaft and does not reverse the direction. One big reason why we'll still be seeing inrunners is gliders. Outrunners are impractical to fit in thin fuselages and the protruding wiring does not help either. Apart from practicality, the comparison clearly favoured outrunners as they are generally suitable for all but high-performance glider applications. And a heck of a lot cheaper.

I'm not experienced with gears but personally I find it fascinating how big props you can swing with it. I also see that Mega Motor has advertisements for a new geared F3A inrunner in magazines so manufacturers still believe in them.

can773

My Feedback: (1)

You need to be very cautious about comparing online postings of brand X motor is 65A and Brand Y motor is 85A. I see many postings that do not indicate the RPM that the readings were taken. This is the most important aspect of being able to cross compare power systems as it provides an indication of the output of the motor.

Obviously a motor turning 500 RPM more on the same prop would have higher amps, but without that information the reader interprets this as the higher amps being less efficient which may not be the case at all.

From what I have read and learned is that when you compare the best inrunners to the best outrunners in bench and controlled testing is that they are only about 5% different, with the inrunner being more efficient.

In the real world this is not really noticeable, as flying style has so much more to do with used capacity than efficiency.

Scott Smith

My Feedback: (4)

I know of 6 inrunners of various manufactures that did not make it though the 09 season. My C50 comp had to go back after 200 flights for a fan failure. If it were only greasing the gear box I would be happy; but in reality it appears the maintenance (and expense) is much, much higher when compared to an outrunner.

KeithB

My Feedback: (1)

Chad, I agree that there are big variables that can't be ignored such as prop size, RPM, etc. Also, looking at the online numbers is meaningless.

My observations are from looking at the Eagle Tree logs you've posted over the last few years compared to logs that I have running a Hacker C50 14XL. You're logs indicate that you pull higher amps with the outrunners than the C50 14XL inrunner.

I'm not trying to start a war, I don't care what motor anyone uses, just sharing my perspective and what I've observed to be the case.

Regarding the cheaper packs, I REALLY hope the price comes down at equal weight and good cycle life. I'll be watching eagerly to see. Unfortunately 25 flights on a non-pattern application with fewer cells, in my opinion, won't indicate the sutability of packs for pattern. Even if the packs are cheaper, wouldn't you still want to treat them kindly and get the most flights possible?

I'll be watching closely as you guys experiment and I'll be right behind you as soon as I see you're blazing a superior trail.

Keith B

vbortone

My Feedback: (2)

I have been flying a Hacker C50 since 2007 season. Probably around 350-400 flights with zero problems. Just lucky I guess...

Vicente "Vince" Bortone

KeithB

My Feedback: (1)

Scott,

I'm not sure why you're having such poor luck, I have over 450 flights on my current C50 COMP with no problems. I've also seen many others here in the Texas area (with super hot summers) get many hundreds of flights on inrunners. In fact, I've never seen one fail at a contest and only "know of" two or three failures over the last four years, two of those were on the original C50 that's no longer made. Not saying failures don't happen, just don't think it's a reason to choose between inrunner or outrunner.

Keith

Velco

I can not agree more on this one! Everyone is just mentioning power or Amps and nobody is mentioning rpm and/or prop type which really can ONLY tell the whole story! Props of same size but from different brands can give up to 30% difference in readings , not to mention the Voltage batteries give under load, from 3,2 up to 3,8 V/cell.

I have a feeling everyone is running after a "better" (more expensive) motor while at the same time good batteries and prop can have a much higher influence on performance.

can773

My Feedback: (1)

Hi Keith,

No war Unfortunately I have not been able to get my eagle tree RPM sensor (the brushless one) to work reliably, otherwise I would share better data Since Futaba took the tach off the 14mz I get kinda lazy taking my 9z to the field to record rpm now

Ryan Smith

My Feedback: (25)

Dang Chad, Great Planes doesn't have a tach in all of their inventory that they could send you?

My tach fits in my pocket, not easily acheived with a 9Z, though your tach can do way more than mine!

DaveL322

Keith,

Static comparison of amps for the Evo and 14XL will certainly show a pretty big difference in amps - but - the Evo is usually turning several hundred RPM more (as is a Neu F3A). What you will also see on the Eagletree is that the amps drop more in the air with an outrunner - so amps in the air for the same RPM and prop are going to be closer together than what is seen on the ground. I've flown most of the popular motors out there, and what I really like about hte Neu F3A is the super smooth throttle response from idle to full, tons of torque. It really does make it easier to fly constant speed. An advantage I've seen with the geared inrunners is faster throttle response - not a big deal in pattern - but moreso for 3D/freestyle flying.

I've logged lots of flights of high kv and low kv inrunners and outrunners in the same plane(s), and I can't find anything in my data to support anymore than 5% increase in efficiency (looking at mah used for equal flights) with the geared inrunners for pattern applications.

Regards,

Dave

Rhilluk

where can you buy the neu motor? Look interesting

DaveL322

Foof,

Ordering for Neu motors in the US is done through Castle Creations -
http://www.castlecreations.com/produ...motors/nm.html

Part number is NEU-F3A-1.

I am not certain if this would be the cheapest way to obtain a single motor for Europeans.

Regards,

Dave

Jetdesign

My Feedback: (8)

There are some EU vendors:
http://www.neumotors.com/Site/Where_to_buy.html


Does a low kV, direct-driven inrunner have the same maintenance issues as a geared inrunner (besides gear maintenance obviously)?

DaveL322

Joe,

Direct drive of any kind should have close to zero maintenance needs - bearings are really the only thing that could wear without breaking. Inrunner or outrunner, low or high KV, should not make a difference.

Regards,

Dave



[/quote]

There are some EU vendors:
http://www.neumotors.com/Site/Where_to_buy.html


Does a low kV, direct-driven inrunner have the same maintenance issues as a geared inrunner (besides gear maintenance obviously)?
[/quote]

EHFAI

Chad / Dave / Keith have lots of experience and provide good info. A couple of additional points are that it's a bit easier to cool inrunners and the planetary gearboxes are very durable (kinda popular in automatic trasmissions also).

The cooling thing was a big concern when I chose the inrunner, I fly a lot in temps at +90F and have had excellent service from both the Hacker Comp & Neu motors. I will point out that the Hacker Comp fans were no problem until an "improvement" was made to improve efficiency by adding a phenolic disc to the fan. These discs do fail and can tear up other stuff - I don't use them. (Simple to remove.)

I originally had concerns about gearbox strength, but not to worry. A 30 min lube job every 100 to 150 flights with a good polyurea grease and all is good.

So it gets down to occasional bearing replacement, in either type motor, after lots of use. Isn't E power great!

pappy35

I was abusing them only to get a feel for how sensitive they were to...eh...less than optimal treatment. I think anyone could get a boatload of cycles with almost any pack if treated them like a cupful of nitroglycerin. My poor test specimens were flown in a 48" EF Extra EXP with lots of wide open, hard, 3D as well as practicing IMAC sequences. I also used them in a small e-jet. The point being that after over 100 flights (on 4 packs) I saw no degradation in capacity.

Not a scientific trial but just a simple torture test to get a quick feel if going electric would be worth it. Now that I'm a believer (or blasphemer depending on the size of your wallet), the next set of packs I get will be treated more rationally (thought those 4 are still running great).

If I had to pay $500 a pack for large applications (700-sized heli's, e-IMAC, 2M pattern) I absolutely would never do it out of fear of ruining said packs accidentally. There are many who drop $500 like I would drop a dollar, but the VAST majority of modelers out there can't or won't. Hobby City lipos make moving to electric, at last, something that's affordable - that old 'nitro vs. electric equation' simply doesn't exist when the packs are in this price range.

Jeff Boyd 2

Hi Keith . .

I personally know of four guys using Rhino and Zippy packs in F3A, and they are holding up strong after 40+ cycles. They are powering Plettenberg EVO, Hacker C50's COMP, and a Hyperion outrunner.

It appears the Rhinos have a slight edge, but they are a little heavier.

JB

pappy35

Keep something in-mind when comparing H-C packs to the 'name brands': Even if they only last, say 50-75~ before showing a capacity drop-off, they are only 30% the cost. That means you're at break-even after only 30 or so ~. Anything beyond that is gravy. Or, it means that you can keep more packs 'in-stock' just in case.

Jeff Boyd 2

Yep . . it's "in-mind"

More packs for me please . . no charging at the field

JB