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May 20, 2020, 11:31 AM
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Soren wolff's Avatar
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Discussion

GWS versus Brushless


Totally new to electric flight, just getting into it. Iíve been flying foam 650mm to 750mm ws. Have all the hardware and electronics to
Build my own. I purchased some brushless motors. Can anyone tell me Pros and cons of GWS v Brushless. Prefer to go brushless Iíve already invested in some brushless motors.
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May 20, 2020, 12:15 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Do you mean "brushed" versus "brushless" ? There is no advantage to "brushed" motors that I know of .
May 20, 2020, 12:23 PM
An itch?. Scratch build.
eflightray's Avatar
The only advantage to brushed motors is if you already have them and they will do the job you want.

Replacing a brushed set-up with brushless to turn the same prop at the same rpm gives little advantage, other than maybe a little weight saving. But at a price, as a brushless ESC is also needed.

.
May 20, 2020, 02:50 PM
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AntiArf's Avatar
Look at when Pat Tritle used the IPS geared brushed setups for models, and you'll see practical specs. They're used on models like the one you just built, very light. The X-Team 12mm brushless inrunner is available in 4500kv which is reasonable for the GWS gearboxes depending on gearing/prop size, if you want to experiment. May require drilling the pinion gears to fit the motor shaft however. I bought a pinion puller years ago, to do such things.

The big miss with the brushed geared setups was not making a light weight gearbox for the 130/180. They're considerably lighter than 300/370 class brushed, but have better brushes than the IPS, which were the 12mm IPS brushed weak point. With better brushes I'm convinced the IPS motors could handle at least 1-2 amps more. I bashed a GWS IPS gearbox to adapt to a 130. Actually flew a 30" Great Planes foamy Hellcat with it. Not fast, but flyable. It's currently in a Herr Pitts and amply powered, with a 9" prop on 3s, same as the Hellcat. Had a number of flights and hasn't burned up.
May 20, 2020, 03:04 PM
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Soren wolff's Avatar
Thread OP
Forgive my ignorance, brand new to the Hobby. I think I mean in runner verse out runner.
And I guess the in runners Have external gearing? Is there an advantage to this type of external gearing mechanism versus an in runner brushless
May 20, 2020, 04:10 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by Soren wolff
Forgive my ignorance, brand new to the Hobby. I think I mean in runner verse out runner.
And I guess the in runners Have external gearing? Is there an advantage to this type of external gearing mechanism versus an in runner brushless
On an outrunner the outside ( can ) rotates , and the inside remains stationary .

On an inrunner the inside rotates , and the outside ( can ) remains stationary .

Inrunners are usually high kv ( rpm's ) and meant for EDF motors .

Outrunners can be lower kv or higher kv . Lower kv is better suited for slow flying airplanes swinging a bigger prop ( like first gear in a car or motorcycle ) .

Not all inrunners have gearboxes , but some do ..... meant for powered gliders mostly .
May 20, 2020, 07:48 PM
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scirocco's Avatar
Using gearing, whether on an inrunner or outrunner is usually only worthwhile when you have severe space constraints, such as in gliders, or you cannot get Kv low enough in a direct drive motor of acceptable weight to run the prop and voltage combination you want.

That is the strength of the small geared GWS inrunners, which are able to turn a larger prop slowly and develop thrust efficiently from the whole system perspective - not just the inefficient motor.

But with light high capacity LiPos, there is less need to extract every gram thrust per watt. A smaller faster turning prop driven directly by an outrunner will be less efficient, but it does the job effectively and most often unless it's a competition situation, effectiveness is most important.

So for the majority of situations there will be be a simple cheap outrunner solution

Enough background. If you've purchased several motors in the hope they will work for your models, you may find they just aren't suitable.

Post the details of the models and the exact motors you have, with links to detailed specs if possible, and someone here will be able to tell you quickly what will work and how well.

PS - you might want to edit the title of the thread, or even close it and start a new one now you have a clearer idea of what you want
May 20, 2020, 07:56 PM
Aeronautical Research Flyer
Rhea's Avatar
Maybe if you would tell us what you are trying to do it would help.
Is this for a 30" Mr. Mulligan?
What size motor do you anticipate etc?
May 21, 2020, 02:19 AM
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Soren wolff's Avatar
Thread OP
Thanks for reply, Really appreciate the information. Yes, 30” Dumas Mr. Mulligan is on the list,
but I have not Fully committed. I believe I could keep the Mr. Mulligan to about 100 g covered weight without internals. I am up for anything in the 30”+ wingspan. Now looking at the Dare kit 36” Monocoupe . Once I have decided on a kit and have reached a point that I have a sense of finish wait I will reach out for any assistance regarding power plant and electronics.
I also agree with closing this thread.
May 21, 2020, 11:04 AM
B for Bruce
BMatthews's Avatar
Having followed this stuff over the years when we first started seeing a lot of brushless motors taking over from brushed the inrunners were still more powerful by quite a margin than the early outrunners. And even with gearing to allow the inrunners to work with decent size props there is still some advantage to them in some cases. It depends on the combinations.

But we're seeing motors now that are tolerant of some really high power handling even if this is only in bursts. Plus outrunners do not have to live with gear whine. The better boxes certainly don't make much noise at all but they do make some.

The big issue is finding smaller and lighter motors for things like this converted rubber scale model you're doing that will have a low enough Kv value that you can use a decent size prop. In the smaller 15xx to 18xx motor size that means something down around Kv=2200 or so. But when you find them you should be able to use then on a 6 to 7" size prop which should be enough. Plus I suspect that for converted rubber scale designs I think you'll find that outrunner motors in this size range are lighter and simpler to use than inrunners with gear boxes. Especially with all the quad motor options out there.

100 gms for the airframe is more than doable. I recently finished a 35" span model that is built sort of half way as heavy as a rubber scale and sport free flight sort of design. It came out at 140gms total weight including a 2S 300mah Lipo on board. Bare airframe was comfortably below 100 grams covered and trimmed without radio or motor. If I'd used a rubber scale plan it would have been easily another 20 gms lighter overall. This uses one of the little Spektrum board with servos setups.
May 21, 2020, 01:07 PM
Registered User
Soren wolff's Avatar
Thread OP
Bruce,
The spectrum board, did it have the integrated linear servos and ESC? I may have to consider now getting one of those.

Rhea,
Contemplating E-Flite Park 180 or 250 brushless as power plant. But they may have to reassess that decision. I have been reading some unsettling things about these motors. Apparently, depending upon how you mount it, you need to ďreverse the shaftď whatís up with that! As of right now, taking into consideration my limited experience that sounds very Tedious and not particularly good for wear and tear on the motor. Anyone having
Experience with the E-Flite park motors with reversing shaft and mounting, Iím all ears!

On a completely different note. More than happy to keep this thread going, But we seem to be digressing from original topic. Personally, I have no issue with that Iím happy to let the conversation grow organically and take on any direction it likes. If you all would like me to discontinue thread, can someone tell me how to do that
May 21, 2020, 03:03 PM
Aeronautical Research Flyer
Rhea's Avatar
I have used Park 180 and 250 motors on a few different planes.
Currently I have a Park 180 on a little flat foam F-22 and a Park 250 on a little balsa wing.
Both are configured as pushers and they work great.

Don't know anything about reversing shafts but because these are pushers the motor has to be spinning in the correct direction for the prop but that is just a matter of plugging in the wires to make it spin the right way. Actually that's no different than any mounting configuration.

BTW the Park 250 is made to run on 2S LiPos where the Park 180 can take a 3S LiPo.
May 21, 2020, 07:40 PM
Registered User
Soren wolff's Avatar
Thread OP
No it’s not for pusher configuration, it’s for traditional front mount and I’ve been reading a bunch of stuff online about having to reverse the shaft by pushing it through. Repaired you I needed to do this on the 250 and 300 not sure if you had to do it any larger size after that. It doesn’t appear as though you have to do it on the 180.
May 21, 2020, 07:59 PM
Aeronautical Research Flyer
Rhea's Avatar
It's not absolutely necessary but it can be done if you wish to do so.
Last edited by Rhea; May 21, 2020 at 09:47 PM. Reason: Clarified (I think) my thoughts.
May 21, 2020, 11:35 PM
Registered User
Soren wolff's Avatar
Thread OP
I am hoping I donít, knowing me Iíd been the shaft.


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