[Dave Hederich]

Some people trying to run the EDF-50 motor in IPS gearboxes are reporting that they are only getting a couple of hours of life out of the motors before they expire. Most of these people appear to be running the IPS-A (5.86:1) with 7x6 props. Dave Robelen has reported success with the IPS-E (10.7:1) and 8x6 prop, so it seems to me that 7x6 is too much prop for the much steeper IPS-A gearing. I think the optimum prop for the IPS-A would be much smaller than a 7x6, and that over-propping is the prime cause of the premature motor failures.

The key question for the people running the EDF-50 motor in IPS-D, -E and -F gearboxes is how many hours of life are you getting out of your motors? And, if you are getting more than a couple of hours of motor life, would you agree that those who are trying to swing a 7x6 prop with an EDF-50 in an IPS-A are over-stressing their motors?

[Dave Hederich]

Wow, five days without a response. Guess no one here is running this combo except Dave Robelen. Dave, do you have enough hours on any of yours to make an estimate on life expectancy?

[fly_joy]

Good question. Sorry I don't have the answer.

fyi, I went a different route with the motor. I'm running it as a DD with a 3/2 prop on one lithium ion cell. It's a nice light set up for a small plane. I've used it on my "Acro-Bipe" with success.

btw, I tried it dd on 2 li cells and it pulled too many amps for the cells to handle. I think once you go much over 2 amps you are pushing these motors.



Let us know what you discover.

Larry

[Dave Robelen]

Hi Dave,
Sorry about the slow response. I just got back from vacation. As far as the life expectancy of the EDF-50 motor, it appears to be just about the same as the others in this line with carbon brushes when the curent is similar. I have yet to wear one out (about 30 flights) running 8 ni-cd cells in my Flap Jack. The key is two-fold- short periods of full throttle, and the higher airspeeds which unload the prop. I hope this helps.
Regards, Dave

[fly_joy]

I'm interested in this geared EDF motor set up but I prefer not to screw around with pinion gears and such.

I have an idea. The IPS twin comes in a 4.8V version. I assume that they are EDF motors. How about if I buy one of the 4.8volt twins and remove one of the motors (which I can use for another plane). Does this make sense?

Thanks,

Larry

As an aside, it seems like wings are amost always powered by direct drives. Why? Is it just the geometry of the set up or are there other reasons?

[Dave Robelen]

Hi,
As the discussion is showing, the EDF motor (and probably the others) need to wind up to pretty high RPM to deliver their best power at a reasonable current. My 10.7-1 gearing with a 9-6 prop results in a motor rpm near 25K, and a static current on 8 cells of about 2.8 A. As I mentioned, keeping the periods of full throttle reduced, and unloading the prop in flight reduce the average current and extend the brush life.
As for using a single motor from the twin unit, it's either back to small props, or high gearing to keep the current under control. I would quickly agree that running a 7-6 on an EDF-50 and A gearing would be way overpropping. I would tach the prop RPM and multiply by the gear ratio to get the motor RPM which needs to be over 20K for any life expectancy. The way the EDF motor is wound, it produces best power at high rpm's and lower torque.
Flying wings and DD? The wings I have seen flying such as the Zagi, etc. are clean and fast where the small high RPM props used with DD are at their best. There is a minor mechanical matter with a geared motor and larger prop where the power unit would have to be moved further aft for the prop to clear the wing. Also, unless the prop is a folder, it will get broken a lot more often.
Cheers, Dave

[fly_joy]

Dave,

I wasn't clear. This twin set up is geared 9.7:1.

[URL=www.aeromicro.com/Catalog/gws_ipsd-rlc-ds__9_7_1__4_8_v__1162875.htm]

I am considering is purchasing this and removing one motor. I assume the remaining motor and gear set up would almost equall your set up.

Larry

ps thanks for the wings comment. "Clean and Fast" says it. I assume the light slower wings like an EAM PopFly or your Mr Bones are better off with the geared set; notwithstanding mechanical inhibitors.

thanks

[Dave Robelen]

Hi Larry,
Boy, I wish the GWS folks would post a few scraps of information on all of these various motors! It may well work out that a "2 minus 1" unit at 9.7-1 would come pretty close. There really is only one way to find out, right? Let us know how it goes.
I have never tried the "Bones" on a DD setup. With the EDF-50 geared, and running on 7 cells, it is a real hoot. I suspect that the props small enough to let the motor "get up on step" would be too small for the airframe. The sp400 series motors have a bunch more low end torque, so the DD drive props are not unreasonably small. It would still be interesting to set up a clean wing with a geared drive, the trick would finding a prop with the right pitch/dia. combination, and preferably a folder.
Cheers, Dave

[fly_joy]

Just thought I would share this inofmration.

After doing a little more research I see that GWS does offer the edf motor in geared set ups. The model is LPS-RLC-C and is offered for sale in the US by www.aeromicro.com

Here are the specs http://www.gws.com.tw/english/produc...system/lps.htm

The only problem is that the max gear ratio offered is 6.2 : 1.

Larry

[Dave Hederich]

This is all good information. Thanks, Dave. It's always tough to give a hard number because people have such different flying habits, which greatly affect motor life. But I understand what you mean about getting the gearing and prop loading right, and then exercising a little throttle management. I think in a year or two we may be looking back and laughing at this search for the best cheap can motor and how to make it live more than a few hours. It appears that we are getting close to having some small, relatively inexpensive brushless motors available that will resolve all of this.

But in the meantime, Larry, I think it has been about 99 percent determined by several experimenters that the IPS-Twin 4.8V motors are identical to the EDF-50 motors. That means that you can buy replacement IPS-Twin 4.8V motors with gears already installed (only $10 each), though I've been having a lot of fun lately pulling gears off of motors with the new GWS gear puller and pressing the gears onto other motors with a small vise. I already bought a couple of EDF-50 motors before learning about the IPS-Twin motors, and now have extra D and E gearboxes to experiment with. I'm scratch-building a Mini-IFOish aircraft, which I think will be ideal for trying a geared EDF-50 motor. Also have some of the surplus Ultralife 700mAh Li-poly cells to try on it (1.5 oz. for a 2-cell pack). Should be lots of fun.

[BEC]

A couple of things (which you know already, Dave H....).

Based on information I've gleaned I am one who is convinced that the EDF motor is the same as the 4.8V motor in the IPS-D drives. Using that information I have assembled an A drive using one motor from an IPS-D-4.8V A ratio drive and a regular IPS-A gearbox. I am running a 7X4 APC Slowfly prop on this setup on either 7 300 NiMH cells or two Matsushita (Qualcomm) 830 Li-Ions. Peak draw is about 2.7A. This setup is in a Todd's Models Wing-E (not exactly an indoor flyer, despite the forum name ).

I have 130 minutes of air time on it so far. After even long flights (20 minutes + on QC830s) the motor (which IS heat sinked) is barely above ambient.

Time will tell how long it will really last like this, but so far, so good.

BTW, for those of you on this forum who haven't heard of the airplane, here's mine. All up weight is 4.5 ounces plus battery, so it normally flies at 6.5 ounces. Span is 23 inches. It's laser cut and goes from bag to ready to cover in less than two hours.....