Questions: IVOPROP Medium IFA

[Eric Page]

After entertaining several ideas for alternative engines, and rejecting each of them for a variety of reasons, I believe I've settled on a Rotax 912iS. Once the applause dies down, we can move to choosing a prop.

One of the props I'm considering is the IVOPROP IFA. I've spent several hours reading through many of the threads in this section of the forum, and it seems that most of the folks using an IVOPROP IFA are pretty pleased with the performance/price of the system.

For those of you using an IVOPROP Medium IFA on a Rotax 912 or 914, I have several questions:

Q1: Are you using a 2-blade or 3-blade prop?

Q2: What prop length are you using?

This thread from 2012 seems to indicate that a 3-blade IVOPROP Medium IFA exceeds the 6,000kgcm² maximum limit for mass moment of inertia on a 9-series engine. I'm leery of putting one on a brand new engine and having gearbox problems (followed immediately by warranty problems!).

Q3: For those running 3-blade props, what's been your experience WRT gearbox wear, vibration, jerkiness during start or shutdown, etc.?

Q4: Has anyone independently confirmed the test result in that 2012 thread, or gotten a MMoI value from IVOPROP?

Thinking ahead to engine mods in the future, I'd like to get a prop that's approved for >100 hp but the IVOPROP website contradicts itself on that point. At the bottom of the landing page it says the Medium is good for 150 hp. On the Medium IFA product page it says 100 hp in one place and 150 hp in another. An apparently older version of that page confuses things even further; it says 100 hp and 140 hp.

Q5: Does anyone know the correct maximum horsepower rating for this prop?

Thanks!

[Maverick]

Ivo's web pages are not the best thing about his business. . . I bought IvoProps for both of my Kitfoxes and found them to be very reliable and efficient. It is the prop recommended by Murle Williams and all the Kitfoxes, that I know about in the Phoenix area (and I don't know them all), are using the medium 3-blade IvoProp. The first Kitfox I built had a Continental O-200. The current Kitfox has a 912uls, both rated at 100hp and I used the medium 3-blade prop on both. My first prop was ground adjustable. This time around, I did buy the IFA and had to send the electric motor back to be rebuilt after 32 hours and during these hours it was used very few times so I was disappointed with it. To the point, the ground adjustable prop would suffice for my purposes and if the electric motor dies again, I'll likely just use the ground adjustable mechanism. I was warned about the IFA motor reliability by one of the locals but, I didn't want to have to deal with the multiple adjustments to find the sweet spot with using the ground adjustable mechanism. As far as how much horse power the medium 3-blade will handle, Murle used it on his first KF-5 which had a Rotax 914 on it so I'm thinking it would work safely on the 912Is but you should give Ivo a call and talk with him if you want the most accurate info.

[Eric Page]

Thanks for the replies, gents. If you don't mind, how many hours do each of you have on your IFA pitch motors since they were repaired?

[Slyfox]

I've got the medium inflight prop. I've had multiple problems with my motor like mentioned above. Now not wanting to loose my prop because I love it, I stayed with it. What I came up with is that the rotosport uk ltd has a maintenance manual that goes through some things. not sure if it's in this or not, they might have a bulletin also. but simply put the white grease that IVO puts in these things is crap, simply said. What I did is I took the gears all apart and cleaned them with brake cleaner and put in new grease, there is another mentioned by the rotosport guys but I couldn't find it and put in Super Lube. that stuff is super slick. I also took the worm gear at the prop end and soaked it in light oil, you can't take it apart. than I lubed the screw end with super lube. I will tell you I found a profound difference in the working of the prop. much faster and goes all the way flat now. I think what is going on is the other, old lube is not good and causes things to bind so to speak and takes out the armature, it will also cause the brush connections to loose connection and even loosen up. very happy with my prop now, hope this helps. I also learned not to let the motor stop and blow the circuit breaker, I quit right when the prop stop changing on the rpm's. make sure your little gears have a nice tight fit on the center holes also.

[Maverick]

I only have two hours on mine since rebuild. The comments regarding the lubricant are rather interesting. Something to be considered. Thanks.

[Slyfox]

one more thing to mention. You don't need to take the prop all the way apart to get the motor off, in fact you can also take all the gears out without removing the prop. unbolt the front, tap off the motor and the middle sleeve, than take out the gears. the trick for install is to install all the gears and than put the little gear that's on the motor in the gears with the flat facing up. than set the motor for the flat up. than stick the motor on. Now you have to make sure the little gear will slip on the armature nice and easy. When these things are new, the little gear goes on tight, reason, there is a ridge on the end of the armature from when they made it, so you have the dress it a little with a file until the gear slips on easy, than your set. hope this helps.

[Slyfox]

I probably have 5-6 hours on my prop since replacing the motor. When we pulled to old motor apart what little grease that was inside looked like ear wax. The new motor lube looked about the same.

it's not the grease in the motor, it's the grease in the gears in front of the motor that's the problem.

[dginok]

I just happened upon this discussion about the IVOProp IFA motor. Not long after my first flight in October of 2017, I started to have a string of failures with the prop electric motor armature. After spending way too much money on replacement armatures, I was determined to get to the bottom of the failures, or at least find a cheaper alternative.


I got in touch with John Holmes at Holmes Hobbies in Missouri. He specializes in custom motors for remote control enthusiasts. The 540 type motor used in the IVOProp is among the motors he makes and sells. John was enthusiastic about helping me find the culprit.


John examined more than one of my failed armatures and determined that the failures I was experiencing were due to the armature windings shearing apart. Eventually, we found that the breakage would occur where the windings meet the tabs connecting them to the commutator. This may or may not be the failure everyone else experiences, but it is definitely the failure I was having.


At some point along the way, I balanced the Medium IVOProp using Dorsal's generously-shared prop balancer. I wanted to make sure I minimized excess vibration as a source of motor failures.


During the time I started having these motor failures, I was developing a constant speed controller for the IVOProp. The many activations of the motor during constant speed operation no doubt exacerbated my motor failure situation.


John Holmes attempted to cure the winding breakage with an epoxy he had on hand. He applied this around the top of the armature, hoping that it would prevent the windings from shearing at the tabs. That attempt lasted only a few hours before I had another failure. John's epoxy was relatively soft, so we wondered if a stiffer epoxy might be the answer.


To make things easier on myself, I decided to try to roll my own armature, making a jig to machine the armature shaft so that it would accept the small gear that drives the IVOProp gear box. Once I was able to machine the shaft, I could experiment with readily-available, low cost armatures.


I followed John's lead with the epoxy idea, but used good-ol' Hysol 9460 to encase the top section of the armature windings. I did that with a twelve-dollar, twenty-seven turn armature I bought off of eBay (actually that was the whole motor; I only used its armature). I have not had a failure since -- about 140 hours so far -- even with the abuse the motor takes from the constant speed controller. I do keep a backup armature handy -- I bought one of the Holmes Hobbies hand-wound armatures, modified its shaft and epoxied its windings.

IMG_20190721_184958648.jpg

[Slyfox]

since I cleaned and switched out the lube in the gears in the system (in front of the motor) I have had very good luck with my motor, not to say I won't, I have another motor that I'm going to now open up and look at the armature and glue for future use. I would definitely be cleaning the gears and putting the grease that I stated above along with the glued armature. My prop now changes very fast and will go to each stop where it wouldn't with the lube that IVO put in. I also found the 3 little gears closest to the motor was wallowed out in the center that rides on the pin.

[rc300xs]

I appreciate your input and thank you! I thought I was alone on this.

I might have led myself down the wrong path but I determined it was heat and too many amps. I tried a resistor as well as a lowering the voltage to 7.2 - 8.4 vdc. What do those two voltages remind you of? I opened the housing and found myself reminiscing of my days building RC cars. I was surprised to see a familiar motor. Impressively simple which I’m a huge fan of.

I had issues with the armature showing an open. After replacing three motors and fixing 2 of them I had enough and went back to the ground adjustable. Each time IVO would send me another RC motor the same thing would happen after 10-20 hours. I started pulling the motors apart and found they measured wide open between the armature pads in all combinations, I narrowed it down to the connection between the winding and the tab of the contact pad. I only once found that it was a broken wire, in my case it was the solder that would become detached from the copper wire and leave black soot around the wire, through the solder under the tab and out the other side. (Like a cold solder joint with black soot) I inspected this with a microscope and it looked like it was literally burned open. I heated the solder and bent the tab up out of the way, then carefully cleaned the copper wire to get the soot off it. Next I measured from tail end to end and the entire winding loop was good. Next a little flux and bent the tabs back down over the wire and soldered it good. I now measured around 1.9 ohms between the pads. After using the motor for a few more hours it would quit again. Upon a second inspection I found the exact same thing. It was like the solder wasn’t attached to the wire anymore. Maybe vibration did this? Not sure exactly but I’ve never in my life seen solder break away from copper while it’s encased in it. (Other than maybe a cold solder joint). Maybe that’s what’s happening as well, again I’m not sure. This same failure happened on three motors and again on both of the motors I fixed. One of the motors I fixed however, on one of the tabs, did show a break in the wire right where the wire meets the solder. I believe that break was due to me removing the goop they had to steady the wire from vibration and centrifugal force, so I could work with it.

Finally I went with a whirlwind and parked the IVO for a while. I called IVO and explained the situation and asked what the solution is. They seemed to NOW acknowledge that I wasn’t the only one with this issue but didn’t directly admit it (I got the feeling from them that this is a known issue now, in previous dealings with them they acted surprised). They said they’ve switched manufacturers and are now selling a new and better motor to resolve the issue. I ordered a motor and yes it showed up looking different. The new style is painted black and has the IVO Prop logo on it. For reference the older style motors are chrome. I tested this new motor and it works, but I haven’t tried it on the plane as I’m looking to sell the works. I’ll install and run it if it doesn’t sell as I love this IFA setup when it works. I should add that when it works it works exceptionally!!! Very impressed and a huge thanks to IVO for making such a great system. Not so much when it quits and I’m 3 hours from home stuck on fine pitch doing 85mph compared to the 115mph I normally get. Or I’m in short stuck on coarse pitch. I learned that lesson once and now I always check the prop that it will go fine pitch before landing short strips.

To sum it up, if the winding maintains continuity with the armature I’m sure there’d be hundreds of hours trouble free operation.

I also completely disassembled the planetary, cleaned and lubricated. Turns much easier now.

Pelican PL
912ULS
Murle Williams through hub mod (highly recommend)
IVO 70” medium 2 blade