Hi Dennis,

This is a good question. I'm sure that others coming into ECL will wonder about this too.

The short answer:

BOTH mounting systems work well! Use the one that is easiest for you.

The longer answer: 

I have the unique (AR? ;-) experience of mounting my AXI 2826/10 motor BOTH ways in the same ECL plane (my ECL P-40). I wanted to see if the cooling would be better if I went from the shaft forward mount to the shaft rearward mount system. It did not make much difference. The shaft forward was only 5 degrees cooler.

I have about 30 flights on the shaft forward and over 70 flights on the shaft rearward mounting with no problems. My highly modified EP Vector has the shaft to the rear mount. If I had to do it again, I would mount it shaft forward on a forward mount, this is how I intend to mount all my future ECL planes. This will allow me to use the rear fan unit that comes standard on my new big Hacker 40 motor. This should help in our warm summers in the SW.
     Please don't misunderstand me about cooling. My present ECL P-40 setup does NOT use a rear fan and my motor temps are only about 35 degrees over ambient. Here at the beach this is fine with motor temps only around 118, but at 105 OAT in LV that gets the motors close to their safe operating limits. I am also trying to do a better job of making my cowls interior airflow more efficient. ... Time will tell?

BTW: Will's Bomber has both of his Hacker motors mounted shaft forward on a forward mount and they have cooling fans in the rear of the motor. They work great with no cooling problems, even in the highest summer heat. I think his setup would still stay cool if Will flew with me in LV.

PROPS: The prop will be mounted differently with each setup. One uses a collet, the other uses a standard threaded shaft. TruTurn makes E-spinner nuts and E-Spinners for both methods, so this should not pose any problems. 

 The fact that almost all the motors come with the shaft comming out of the "bolt it to the front of the plane side" of the motor tells me that this may be the optimal side that the designer wanted to be in the FRONT of the plane. This is also further shown to be the case when using any motor with a cooling fan installed like the excellent Hacker motor that I am using in my next ECL plane, and the ones Will uses in his great ECL Bomber. It requires a forward mount to use the fan.

It is obvious that the E mfg. are trying to accommodate all the IC to EP conversions out there. In my E-RC planes I have planes using both systems. Most of the conversions use the rear mount, and the ones that were EP from the beginning mostly use the forward mounting.

Again, the good news is that they both work well.

Regards, 

Hi Dennis,

Thanks for your kind words. ECL is evolving at a fast pace. As more people in CL transfer the E-RC knowledge over to ECL, the pace will quicken. Will, Mike, Bob&Dean, Linhart, Ron King, Kim, and many others have been a big help to many on this list. I think Will's column in SN has been a great help in spreading the word on ECL.  You are asking a lot of good questions. I am sure others will chime in with more answers for you.

1. Round Motor planes like WWII fighters and bombers are perfect for shaft forward mounting. Also wide cowl planes like the Extra series, Edges, etc. are very good. I modified my ARC Vector by cutting off the fuselage at the wing LE and completely rebuilding it to look a little like my 35% Extra 300L. With the scale paint scheme I think it looks OK, maybe the middle of row 4 in a 4 row contest?      BTW, it would have been a LOT easier just to make a whole new fuselage than do it the hard way like I did. At least I learned a lot about how NOT to do it next time!
     It is very easy to get the E-spinner nut for the shaft. Most hobby stores carry them for RC. Yours is most likely a 5mm shaft. You can also order them form Hobby Lobby, an excellent source for E stuff. I order mine from TruTurn. They make great, light weight E spinners and spinner nuts. The size we use is 5mm x 3/4" or 7/8".

2.  I tried the full spinner for the 1st few flights on the P-40 but it seemed to block too much of the cooling air. As strange as it sounds, a cowled in motor gets much better cooling (if done properly) than a motor hanging out in the breeze on a profile gets. This is true in FS also. I use the 3/4" spinner nut on my P-40 and on the E-ExtraVector. If you do want to use the TRADITIONAL CL full spinner, you will have to have a large intake somewhere to bring in cooling for everything. ..... I'm glad I tried the motor both ways in the same plane, I hope it helps others in their quest for the perfect setup.

3. Pls. see #2

4. I proposed this as a cooling solution several months ago. Dean was kind enough to give a very good reason why it will most likely not work well. His detailed ans. is on this E forum somewhere. In a nut shell: "..... the air in the spinner is swirlling around with such force that it would throw the air out the slots and not get to cool the motor ...." When Dean speaks, I listen, he knows his stuff.

5. IMHO: Yes! Cooling Fans were created mainly for the E-Heli flyers. Their motors live in a brutal environment. They draw very high amps with very little air moving over the motor. We in ECL are much closer to Helis than we are to ERC fixed wing planes. We are at high power for 5.5 min. with NO relief for the motor like in E-RC where there is plenty of low TH cooling time during our flights.
    One of the reasons Will and I are going to cooling fans is that our E motors like to run as cool as possible for MAX efficiency. They would really like to be closer to 0C than to the temps we run them at. The other reason I recommend fans is that not everyone has the talent and knowledge of the Bob and Dean team to make a very efficient cooling cowl system to move the air where it always does the most good. A fan makes up for our amateur, "less than perfect", cooling duct systems.

6. Yikes! "400F" .... This may be the temp when the magnets stop being attractive to each other and file for divorce, but it is about 260F higher than the MAX recommended temp for our motors. Most Mfg. recommend a MAX operating temp of around 135F to 140F. If you operate above this level your motors life span will be shortend, the magnets will weaken, and the motor will lose power over time. As we approach 170F to 200F the motors life span will be as low as <50 flights. As we go over 250F we start to run the risk that the glue holding the magnets may begin to weaken and fail.
   I know that the E speed pylon racers cook a lot of E motors(and batteries) by running at very high temps, but they are going all out to win and look at motors like we IC pylon racers look at glow plugs, one or two flights is SOP.

FWIW When I give you my motor temp readings, they are actual in flight readings from my on board Eagle Tree data logger with a temp probe attached directly to the motor, and one probe to the battery. This unit also gives me real time RPMs showing the changes every 1/10 sec during the entire flight and for each maneuver. it also gives me Watts, mAh, av. and mins/maxs for each flight. It's a cool tool. :-)
  
BTW: A good rule of thumb recommended by the motor mfg. is that you should be able to touch your motor right after a flight without any pain. If you can't hold on to your motor, it is too hot. This is also the same rule of thumb for our batteries. ..... Our batteries actually like to be a little warm for MAX efficiency. Somewhere between 95F and 110F is where they are happiest and at max power. but they too are sensitive and should not be run at over 130F, or their life will be shortened. 

7. Your more than welcome, glad I could help. :-)

Regards,    

Rudy: ANOTHER thorough & well constructed post - THANX! 

1. Our experiments (that is the only word that really fits) so far have been with the shaft-forward nose-ring mount, got some new motors that came with shaft-aft firewall mount.  However, we are also looking at new fuselages that are naturals for firewall mount - I'll have to get some prop adapters for the shaft-forward mounting.  I have not tried fitting e-power to a Vector, but I know it has a really snug front end, I can see why a rear mounting would have been the odds-on favorite!

2. Of course your post raised ANOTHER issue that I had not considered - cooling.  We are currently flying without a spinner and with the nose ring plate clearing the cooling openings - its about as good as it can get.  Your forward versus aft mounting experience with the P40 is golden:

3. *Have you been running with a spinner (2"?) all the time?

4. *Has anyone had any success "ventilating" the spinner to allow some flow to the motor?  Seems like a few well place holes should allow some flow directly into the motor.  Done right it might even look REALLY cool!

5. * Do you think we should all plan on using fans routinely?

6. * Just how hot is the limit?  I thought magnets did not start giving up until 400F or so...?

7. As always THANKS for your feedback & advice!

Rudy & Dean:
After I posted I "went diggin" in StuntHanger messages and FOUND the thread on spinners.  Also found info on temperature & magnets (iron magnets will tolerate higher temps than 140 - but we ain't using them!)

Nice rule of "thumb" on motor temperature - if you can touch the motor (with your thumb?) its OK if not its too hot!  Gee this is close to how I measure how my IC engines are cooling!

* I completely concur on cowled engines cooling better than open ones - that is the case in IC engines too.  I have been focussing on ideas for getting air THROUGH the motor, but it occurs to me that I am under-appreciating the importance of cooling the shell.  Possibilities there include:

>> Remove the "blanket" - i.e., the label, and expose the metal to cooling air stream.  May the manufacturers forgive us, or better still, they start inking or etching their labels in place!

>> Sandblasting!  just as we learned with IC engines that a sandblast finish increases the surface area and significantly improves cooling - ought to help on outrunners too!

>> Unlike IC engines, the spinner CAN be an effective heat sink for an electric - so as Dean(?) pointed out, I gotta quit using plastics!

* I like the idea of a "reverse" cooling path especially for a front mounted motor.  Should be easy enough to compartmentalize the motor then pressurize it.  The airflow exit path would be FORWARD through the core and then vent out the spinner openings around the prop!

* The only negative on cooling fans is that if it is working it will absorb power.  Then again, a poorly executed set of scoops & such can add drag and/or rob thrust.  The add-on fan sounds like a good "tool" to have in the arsenal, but I think my primary path effort should be on passive cooling measures...

I think I'm about to go over to the "dark side" and abandon my slimers!

I'm not into electric (yet) but am thinking(?) about things!

I do recall though during several stints working in hobby shops heavy into R/C car racing, there were "clamp on" heat sinks with cooling fins built in. These sort of snapped on the main housing of the motors to assist in the cooling process. Are these not available, or ineffective for brushless motors or what? I even built some e boats that had water cooling tubing wrapped around the cases!

W.

if you really need cooling (poor venting around motor back of the spinner or too hot days or I do not know what) you can have such thing for several motors, or even you can have one with buit in cooling like MVVS:
http://www.mvvs.cz/obrMVVS/elektro/4.jpg

or you can have extra accesory like for axi:
http://www.modelmotors.cz/products/chladic02a.gif
http://www.modelmotors.cz/products/chladic02b.gif

I measure the axi fan, it takes only 1 or 2 Watts of input power so it does not mean any extra higher iddle current on top. (~40mA)

Igor,
   Kim Doherty also praises the fans offered for the Plettenberg motors. He made the same comment as you, they take very little power to turn for a lot of extra free cooling. The fans are plastic, so they weight just a few grams.

   I can't say you will never need a fan, but if you do, your not paying much or any penalty. Just more options to choose from. 

Mike   

I agree with Mike, listen to what Kim says!   


Seriously,

With respect to cooling fans, there are two worlds at work here. One is theoretical and one is practical.

In theory no, you should not need a cooling fan if EVERYTHING is calculated just right and the ambient temperature is not 120 in the shade and you are not testing a new bigger prop............

In reality yes, a cooling fan costs practically nothing in either weight or performance. (If this is the straw that breaks the camels back then you were using the wrong motor/esc/battery/prop combo) We do not always calculate things to run at just below their practical limit.

Perhaps the biggest issue you should consider is that R/C pilots can (and do)throttle their motors up and down. If something is not right, they can simply abort their pattern (or whatever they are flying) and land. When you light the fuse on an electric control line model, you are going to fly ( in my case with F2B) six minutes and twenty seconds without shutting off. Once you release the model there is no turning back and saying Oops that may be more prop than it can handle can I please start over.

Batteries need to be more than warm to operate efficiently. Motors would operate best if the windings were near absolute zero. Electrical and magnetic efficiency deteriorates as temperature climbs. Do you want more or less efficiency?

So you will always see me run a fan. It is simply good practice and will prolong the life of your equipment.

Kim.

OK Kim I'm listening too!     

* Looks like the fan as shown on the AXI would require using a front mount, then require either no spinner (spinner nut) or some kind of open spinner - to allow air in through the front so the centrifugal fan can pull the air through and throw it out the back - right?

* Next step would be a carefull venting of the engine  - uhh, I meant MOTOR - compartment SO the hot air exited through the motor does not then just heat up the motor shell.

* Is the AXI fan plastic?


HEY YOU GUYS USING REAR MOUNTS:
Do you use a solid firewall mount to or do you "ventilate" the firewall to allow the cooling air to pass?

getting in over my head..... 

* Is the AXI fan plastic?

metal

it's good to be simple minded, 'cuse that makes things lighter ...
          Dean P.

HEY I resemble that remark!!    I might be Born to be electricuted  (or something like that) 

"Simplicate & add lightness!"

This has been a VERY helpful thread THANX to all!     

Dean:
I think the first quote was Henny Youngman! 

"Simplicate & add lightness" was attributed to Geoffrey DeHaviland. 

Guys,

The AXI mounts and prop adaptors lend themselves easily to rear mounting. Like Bob and Dean, I carefully cut my plywood mount to match the metal "X" AXI mount. Thus, I had ventilation through three holes in the back (the wires go through the fourth hole). I had no cooling issues with this, even using a full spinner (Tru-Turn - with the ventilated back plate).

For my next electric, I am thinking about a round cowl, like the Hughes Racer. The mistake I made with the first Alouette-E was to make the fuselage too tight. There's not enough room in there to change my mind. 

BTW - I'm baaaaack.    Spent the past year working with some electric UAVs and learned a lot. Hope to incorporate some new ideas in my CLPA electric program soon.

Take care,

Ron