Do you prefer direct drive or geared? A WattFlyer.com poll

[zappedalaskan]

Originally Posted by ron_van_sommeren

A belt-geared Torcman 685 'Monster' outrunner in a Klemm 35 built by Franz Schmidt.

Ron,
What does that thing run for batteries? That is a nice set up. Very impressive!
Regards,
Jay

[ron_van_sommeren]

Sorry Jay, I could not find information on (number of) cells used.

[CorsairJock]

Altho I have heard a few geared motors that had a very realistic sound (gearbox noise sounded like full scale internal combustion engine), I prefer the simplicity, low maintenance, and nearly equal efficiency (maybe even equal) of todays modern brushless outrunners.
Cost wise tho, it's a tough choice in some cases. For instance: the HiMaxx 2015 and 2025 series geared combos sell for less considerable less than AXI outrunners with equal power, especially if you factor in the optional (but highly recommended) AXI mounting/ prop adapter kits.

[TeslaWinger]

Just when ya think its all black and white everything fades to shades of grey. It was also my understanding that outrunners didnt need geardrives- - til they started appearing as replacements for brushed motors- Speed 300, 400, 600!

It all depends on the torque/speed balance needed to support a given prop and airframe- and what you are prepared to put up with (10% gear eff loss, weight, expense, bulk, maint) to get it. Simpler is always better. Zero maint is better yet!

Direct drive to go fast with its very high pitchspeed and tiny prop.
Disadvantage-Won't climb a slower, larger glider very well with its small diameter -and disc AREA. At some point the sheer VOLUME of lower speed thrusting air is a bigger factor than a high pitchspeed when the prop's scaled up with gears or a wide motor design.

0r

With the flood of new outrunners find one closest to your needs (or be a man and build your own ) and enjoy the lightweight efficiency but you still won't be able to fit a big 'radial' where an 'inline' needs to squeeze so there are decisions to be made unless you want to explore buried motors and weedwhacker drives for those snarky scale jobs! Good luck with that shaky snake, wingman!

It is the difference between a P-47 Jug and a P-51 Mustang. A Wright Cyclone or a Merlin... Style is everything once the powerplant's hummin- but if ya wanna have a hit- ya gotta make it fit!

Straighten up. Fly right.

TW

Uh oh...

Maybe you need another 20 or so more categories of in/outrunner definitions- the number of winds says more than anything else about how it works- and determines if it will be a candidate for a gearbox or not- or whether it does the job direct with its wide torquey ways and the windings power to haul the mail! Let's not forget N38, N40 or N50 neodymium magnets... each question will require 14 calculations and an engineering staff.

[Rittenflyer]

Outrunners rule! Gearboxes are interesting but the inexpensive ones all sound like they're eating themselves; the grinding sound just grates on me. I don't mind a little noise on electrics, but I find that my outrunners let the prop noise come through, which, although quieter than a gearbox, sounds more realistic.

[crast test dummie]

I voted for outrunners but I like inrunners for Direct Drive high speed applications. I couldn't vote for more than 1 choice other than the I like them all catagory. I havn't been crazy about GB's in the past due to some GB breaking mid flight causing and emergency landing or worse the loss of your plane!! I have been told not to swear them off cause Himax, Cobri and some others make very high quality GB's. I had a Park 400/4200 motor I got for the Mini funtana and after 2 GB's broke on me I took the motor out and there it sat for months. Well I just got a Himax GB for it and I'm giong to give it another chance. We'll see..............

CTD

[Rugar]

Originally Posted by crast test dummie

Well I just got a Himax GB for it and I'm giong to give it another chance. We'll see..............

CTD

If you try pushing much more then 150 watts thru that Himax G/B, you will still have trouble with stripping gears. When you mount the motor to the Max G/B make sure that the sticker on the motor is not facing down. The sticker allows for a sloppier gear mesh which is what causes the gears to strip.
The best G/B is the Cobri. I push 275 watts thru it on my Mini Funtana and have not changed gears in over a hundred flights. Many have ran a Cobri G/B over 300 watts without a problem. The gear mesh on a Cobri is adjustable, the Himax is not.

[crast test dummie]

Originally Posted by Rugar

If you try pushing much more then 150 watts thru that Himax G/B, you will still have trouble with stripping gears. When you mount the motor to the Max G/B make sure that the sticker on the motor is not facing down. The sticker allows for a sloppier gear mesh which is what causes the gears to strip.
The best G/B is the Cobri. I push 275 watts thru it on my Mini Funtana and have not changed gears in over a hundred flights. Many have ran a Cobri G/B over 300 watts without a problem. The gear mesh on a Cobri is adjustable, the Himax is not.

Do you mean the sticker on the motor that displays the motor size and KV? I have never herd that before, but that don't mean anything. I have been in this hobby for just over 2 years and I find I learn something new almost everyday.

Thanks,
CTD

[Rugar]

Originally Posted by crast test dummie

Do you mean the sticker on the motor that displays the motor size and KV? I have never herd that before, but that don't mean anything. I have been in this hobby for just over 2 years and I find I learn something new almost everyday.

Thanks,
CTD

Yes that sticker. Its not very think but you need to be able to get as much gear mesh slop out as possible to make the gears live. The Himax motors have a thick sticker that wraps all the way around the motor. I always remove it. I'm only still using one Max Gear Box now and I limit it to my Slow Stick. My other geared setups all use Cobri's. The Cobri's are also much quieter also and have over 70 differant gear ratio choices instead of three like the Max G/B does.
Link to E-Flightline for the Cobri's.
http://e-flightline.com/

[crast test dummie]

Rugar,

Thanks, for the link. I'll have to look at my motor when I get home tonight. I wouldn't have even thought about the thickness of the sticker being an issue.

See, it is true. If you pay attention you will learn something new every day.

CTD

[rclark]

Outrunners ... Love the simplity. Plenty of power. Plenty of motor choices with AXI, Hacker, and Apache (and others) out there. Have a couple of Himax small motors as well....

Inrunners .... The only one I'd buy now is the nice Mega motors 1615/xx series. I like running them DD as a drop in replacement for brushed 400 motors.... Really kick up the performance over brushed 400/480 motors....

I still fly a couple planes geared (have motors on hand) but so far I've never been disappointed with an outrunner.

[Mike Parsons]

While writing a review recently, I had the opportunity to go either with an inrunner or an outrunner. I decided to throw them both on my test stand to see how they performed. Amazingly similiar.

The test subjects were a Park 370 4100 kv geared 6.6:1, swinging a 12X6
and a Park 400 outrunner DD swinging an 11X4.7 APC. I decided to take the test one step further and fly both motors one after the other to see if the extra inch in disk diameter made a difference even though clearly the numbers made them equal. Those results hopefully this weekend.

-Mike

[TeslaWinger]

Originally Posted by Mike Parsons

While writing a review recently, I had the opportunity to go either with an inrunner or an outrunner. I decided to throw them both on my test stand to see how they performed. Amazingly similiar.

The test subjects were a Park 370 4100 kv geared 6.6:1, swinging a 12X6
and a Park 400 outrunner DD swinging an 11X4.7 APC.

Excellent, Mike!

Just the kind of really relevant stuff I need- so we don't have to agonize over bad motor/battery/prop choices that kill all the fun and make new guys quit when they realize its more fun to walk the dog- than to fly one!

CRASH, ya GOT IT, bro! If there was nothing more to learn then most of us would have quit long ago in pursuit of something more interesting... Just ONE new thing a day? It's like drinkin' from a fire hydrant sometimes!

Oh to be a newbie in the Internet age. That sure woulda helped way back when.
Good job.
TW

[Doppelganger]

Direct Drive. Simple.......like me.

Steve

[crast test dummie]

Originally Posted by TeslaWinger

Excellent, Mike!

Just the kind of really relevant stuff I need- so we don't have to agonize over bad motor/battery/prop choices that kill all the fun and make new guys quit when they realize its more fun to walk the dog- than to fly one!

CRASH, ya GOT IT, bro! If there was nothing more to learn then most of us would have quit long ago in pursuit of something more interesting... Just ONE new thing a day? It's like drinkin' from a fire hydrant sometimes!

Oh to be a newbie in the Internet age. That sure woulda helped way back when.
Good job.
TW

Roger that!

CTD

[Unbalanced prop]

Originally Posted by Mike Parsons

While writing a review recently, I had the opportunity to go either with an inrunner or an outrunner. I decided to throw them both on my test stand to see how they performed. Amazingly similiar.

I have also noticed this. I happen to have two identical planes (Gary wright's Sport-E). One has an AXI 2820-10 outrunner and the other has a Mega 22-20-2 geared at 3.18 - 1 in a MEC gearbox. I fly both models with an 11 x 7 APC-E prop and 3S2P packs. They have very close performance figures on the bench and perform almost identically in the air.
But as mentioned before, the Axi has no maintenance to perform on it while with the MEC, gears must be looked after once in a while. The advantage on the geared setup is the ability to change the prop and gearing to change the performance of the plane.

Doug

[Mike Parsons]

Exactly Doug. With such similar performance it boils down to a decision of do I want maintenance free or flexibility?

[Jason T]

Mike,

Good test. I am amazed that they are so similar.

[jrb]

It’s perceived convenience versus efficiency!

Mike’s numbers above give the nod to the in runner based on efficiency. Note efficiency is not thrust divided by watts; though it shows the trend – thrust raised to a power of 1.5 is closer to the real answer of thrust times velocity divided by watts for propulsion system efficiency.

Too bad the E-Flite numbers are not too good; or the various Calc’s (E, M, P, etc.) would show it in their results too. I say their numbers are bad since they neither give good results (outrunner specifically), and they don't trend as they should -- a hotter motor should have a lower resistance and more no load amps, lower Kv mean more turns of wire.


YMMV, based the happiness of the flight tests; but efficiency comes more into play when the watts go up by an order of magnitude or so!

[tone]

the MEGA 22/20-2 has a kv of 2875 divided by the 3.18 = 904 effective kv.
the AXI 2020/10 has a kv of 1100 direct.

the axi "should" be giving you about 2000 rpm more than the mega (on 3S at about 10 volts under load), but probably isn't by a long shot.
so the theory is that the AXI should be a good bit better, but this shows the efficency losses of direct drive versus geared.
The geared performs as well (subjectively) probably because the outrunner isn't as efficient.

just guessing here...

[Unbalanced prop]

I never really thought about it that way Tone.................but it makes sense to me too. Your "guessing" sounds good to me.

Doug

[philmaur]

Originally Posted by TeslaWinger

. . . .

Maybe you need another 20 or so more categories of in/outrunner definitions- the number of winds says more than anything else about how it works- and determines if it will be a candidate for a gearbox or not. . .

And another 20 categories to define the type of model? Although several contributions have referred to this issue, I don't see how you can have such a poll without including the type of model. I doubt if anyone would consider direct drive in-runner for a helicopter nor would they use a geared outrunner for a pylon model (yes there are already geared outrunners such as the Cyclon).

In the competition scene which invariably flows on to general sport applications, it is all a question of two factors - output power to weight and a match of the prop to the application. In the Pre Outrunner days, the only way to get a high power to weight ratio for the big props needed for fast vertical climbs was to use a gearbox. We even flew geared ferrite 'buggy' motors in pylon for a while to push the input power levels up to 400+ watts

Now, things are changing and the outrunners are beginning to challenge all but the best of the geared in-runners for vertical performance. Give another year or two and they will narrow the gap even more. Then the cost and reliability factors associated with gearboxes will see their demise or diminished use. So IMHO, for the majority of applications the outrunner will reign supreme, with the exception being the fast pylon racers type or similar high speed models

Phil

[FlyWheel]

My EasyStar came with a brushed inrunner, but if I had ever needed to replace it with a brushless I would still use an inrunner because it would fit in the plane better and due to the prop size limitation I think the higher RPM would have worked better. My Miss Stik and my Skimmer however didn't have these limitations so I chose a brushless outrunner for both. I even modified the front of the Skimmers' fuse in order to fit the OR.

My next project is a 1913 Eastbourne in which the plans call for a Speed 400 and a gear box. Obviously I'm going to replace the brushed can motor with brushless, but sinced it is balanced for it I am going to go with an inrunner and keep the gearbox.

So it depends on the plane.

[hayofstacks]

Holy thread revival.

I'd run a lighter brushless outrunner and a bit bigger battery if ballance was an issue.

[FlyWheel]

Sorry about that. Sometimes I do a search on a subject, find something interesting that I want to comment on and forget to read the posting dates.