Electric C/L

[Glenn Kirms]

Wondering if anyone can help me with the problem I'm having. I have a Brodak Super Clown C/L Electric that I just finished up. This is the issue. I start it up and it seems fine until it goes into full power and then the propeller and prop adapter just come flying off the shaft. I have tried it numerous times with the same result. The wires are connected correctly since the prop runs clockwise when looking at it from the back of the plane towards the front and everything is tight. At this point I'm at a loss on what to do to solve this issue. I haven't flown any control line in about 25 years and I thought electric would be a nice alternative to gas because of where I live. Any suggestions would truly be appreciated.

Have since corrected the issue with the help of Motoman.  Easy fix, shaft nut to hold motor in place was never included and being new to electric I didn't realize it. But now, motor runs great and plane flies great. Still needs some adjusting on the speed and on the stabilizer.

Thanks to everyone who replied. 

[Tim Wescott]

It's not tight enough, or the adapter isn't a good fit to the shaft.

[Ken Culbertson]

Wondering if anyone can help me with the problem I'm having. I have a Brodak Super Clown C/L Electric that I just finished up. This is the issue. I start it up and it seems fine until it goes into full power and then the propeller and prop adapter just come flying off the shaft. I have tried it numerous times with the same result. The wires are connected correctly since the prop runs clockwise when looking at it from the back of the plane towards the front and everything is tight. At this point I'm at a loss on what to do to solve this issue. I haven't flown any control line in about 25 years and I thought electric would be a nice alternative to gas because of where I live. Any suggestions would truly be appreciated.

I have an issue with the collet not compressing enough on my Cobra's with a 5mm shaft, but I have never thrown a prop.   Are you using a set screw or compression type?  The flats on the Cobra don't line up with any of the collets I have tried and the compression ones don't grab enough unless I trick them.  This can't be the norm so if any of you old time electric types have a better collet let me know!

I have to pull on the prop to get enough squeeze on the collet for it to really tighten.  Mine came from Horizon Hobby.

Not likely but you might also check the ESC and make sure you are not getting a sudden 100% brake.  You may be overheating or getting a sudden RPM change.  Does the motor keep running after the prop is gone?  Another problem might be the ramp up speed.  Those motors put out a tremendous amount of torque.  I have seen them literally rip the motor mounts off of a ship if the spin up speed was set too fast.  I let mine take about 5 seconds.  Makes for a very realistic take off!

Don't give up.  Once you get the kinks out, electric is wonderful.

Ken

[Dennis Adamisin]

The adapter has three main parts, the collet, which is the center portion that slides over the motor shaft, the thrust cone, which is the part behind the prop which also has the cone that clamps down on the collet, and the prop nut (or spinner nut)  What can happen is when you try to tighten it the pieces start sliding relative to one another - which means you THINK you are tightening it but it only goes so far then its just spinning.

I think your best shot is to try grab the prop and drive thrust cone (behind the prop) and prevent any sliding (easier than it sounds.

Another thing to check:  if you are using a spinner nut it is also possible that the threaded part is bottoming out on the end of the adapter shaft.  This could happen with a very thin prop hub. if this is the case then adding a washer in FRONT of the prop and behind the spinner nut should do the trick.

If neither of the above I suggest you contact Brodak and ask them to send you a different adapter.

[Glenn Kirms]

I have an issue with the collet not compressing enough on my Cobra's with a 5mm shaft, but I have never thrown a prop.   Are you using a set screw or compression type?  The flats on the Cobra don't line up with any of the collets I have tried and the compression ones don't grab enough unless I trick them.  This can't be the norm so if any of you old time electric types have a better collet let me know!

I have to pull on the prop to get enough squeeze on the collet for it to really tighten.  Mine came from Horizon Hobby.

Not likely but you might also check the ESC and make sure you are not getting a sudden 100% brake.  You may be overheating or getting a sudden RPM change.  Does the motor keep running after the prop is gone?  Another problem might be the ramp up speed.  Those motors put out a tremendous amount of torque.  I have seen them literally rip the motor mounts off of a ship if the spin up speed was set too fast.  I let mine take about 5 seconds.  Makes for a very realistic take off!

Don't give up.  Once you get the kinks out, electric is wonderful.

Ken

Without the prop the motor runs fine and there's no issues.  Once I put the prop on and it gets going there's a sudden bang and off the comes the prop but the motor keeps going.  I have turned down the power to its lowest and I tighten up the spinner nut as tight as possible.  With this being my first time using an electric motor I'm out of my element.  I've taken video of the propeller falling off if anyone wants to share an email with me and I will gladly send over the video.  At this point this plane will never see its first flight.

[Tim Wescott]

Without the prop the motor runs fine and there's no issues.  Once I put the prop on and it gets going there's a sudden bang and off the comes the prop but the motor keeps going.  I have turned down the power to its lowest and I tighten up the spinner nut as tight as possible.  With this being my first time using an electric motor I'm out of my element.  I've taken video of the propeller falling off if anyone wants to share an email with me and I will gladly send over the video.  At this point this plane will never see its first flight.

Can you post the video to YouTube and share a link?

Give that three people have given you three different valid reasons that you could tighten the nut as hard as possible and still not have the collet tight on the motor shaft -- have you done anything other than trying to spin it up to see if it's tight?  Like, maybe, giving it a tug when you're done?  Not being able to pull it off with your bare hands won't mean that it's tight enough -- but if it slides off with the nut tight, that will definitely narrow down your problem.

[Perry Rose]

I have a Brodak electric set up and the collet is not easy to get on the motor shaft. If yours is easy to slide on the motor shaft it's too big.

[Ken Culbertson]

Without the prop the motor runs fine and there's no issues.  Once I put the prop on and it gets going there's a sudden bang and off the comes the prop but the motor keeps going.  I have turned down the power to its lowest and I tighten up the spinner nut as tight as possible.  With this being my first time using an electric motor I'm out of my element.  I've taken video of the propeller falling off if anyone wants to share an email with me and I will gladly send over the video.  At this point this plane will never see its first flight.

Have you tried another collet?  I was a machinist at one point in my life and all machining processes have "tolerances".  The shaft is 5mm +- something.  The collet is drilled to 5mm+- something as well.  Sometimes luck of the draw gets a motor that is on the "-" end and a collet on the "+" end.   Both passed QC but together they fail.  In a process like mfg. engines, the parts would be matched and fit perfectly.  When you have to mail order from different sources you get what you get.  A trick I used on a rather stubborn one was to widen the slots in the collet slightly which let it tighter better.  It is also possible that the thrust washer is too big (tolerance issue again) and is not putting enough pressure on the collet.

Now this one is a possibility that comes from thinking too much.  I am curious what that "pop" is.  Just out of curiosity, what is the prop size and RPM?  I get a "pop" every now and then in corners.  I think it is cavitation.  The tips are going really fast.

Just out of curiosity, have you tried running the motor up without the prop?  A short run will not damage anything.  It would be interesting to know if it does anything weird when it goes from spin up to full power.  Still my money is on the "Crappy Collet" theory.

Ken

[Glenn Kirms]

The center of the collet comes through the drive washer. If your prop is not relieved to clear this, then you can tighten it all you want but you're not squeezing the collet. Might have to bore the prop hub deeper in the back.

I make my collets out of alloy steel so I can tighten the prop all I want. Had a few of the aluminum ones break.

Motorman

@ Motorman I live in Northfield, NJ so not far away from you. What would be the chances of trying to hook up some weekend and I'll bring the plane with me.  I appreciate everyone's replies but with so little experience under my belt not sure if I'll ever resolve the issue.  Let me know. 

[Glenn Kirms]

Can you post the video to YouTube and share a link?

Give that three people have given you three different valid reasons that you could tighten the nut as hard as possible and still not have the collet tight on the motor shaft -- have you done anything other than trying to spin it up to see if it's tight?  Like, maybe, giving it a tug when you're done?  Not being able to pull it off with your bare hands won't mean that it's tight enough -- but if it slides off with the nut tight, that will definitely narrow down your problem.

Please see attached link for video:  After the watched the video again I noticed when the engine goes to full power the motor actually moves backwards so not sure if this is why the prop is coming off. 

[Dennis Toth]

It sounds like something is rubbing. Does it make the same noise without the prop? Have you tried to run the motor and prop out of the airplane? If you remove the motor from the ship then mount the prop. Grab the motor can and try to twist the prop, it should be solid. If it moves the collet is to big or the thrust cone has spread and is not tightening the collet down, try a different adapter.

If it is tight then you need to look into the motor mount area. See if there is something that could interfere with the free spinning of the adapter/motor can.

Also check the ESP/timer setup  so that something isn't fighting the rpm setting or spin-up function.

Best,    DennisT

[Ken Culbertson]

Please see attached link for video:  After the watched the video again I noticed when the engine goes to full power the motor actually moves backwards so not sure if this is why the prop is coming off. 

I am with Dennis on that one.  W/o the prop an electric makes almost no noise at all.  If it makes that noise w/o the prop you have a bad motor but that doesn't explain the prop coming off.  It makes noise when it arms too - it should just make a whir.  I have a Cobra about the same size that was damaged when I shorted it during installation.  It makes a similar noise but it won't spin up to full speed.  Almost acts like a bent shaft or a grossly out of balance prop.  Does the plane vibrate when it ramps up?  Electric's don't vibrate like an IC unless something is out of balance.

Does your collet bottom out on the shaft?  If it does, just for grins move it up about 1/8"

Ken

I forgot to ask earlier - what is the history for that motor?  Has it been crashed or subjected to some electrical misadventure?
I listened to the video carefully and it sounds like it is making that noise AFTER the prop is gone.  What shut off the motor?  I also noticed that the motor lurched back then forward as the prop comes off.  That tells me that your mounts are flexing.  Not necessarily bad.

Ken Again

Another observation is that sudden rpm shift.  I don't use the same motor or esc but all of my electrics (I have 3 in service) ramp up smoothly.  Yours looks like you shifted from about 3,000 to 9,000 rpm by popped the clutch but that just tears up you mounts, it might cause the prop to slip but it shouldn't throw it - unless - the shaft is bent or the prop is way out of balance!

[Brett Buck]

Please see attached link for video:  After the watched the video again I noticed when the engine goes to full power the motor actually moves backwards so not sure if this is why the prop is coming off. 

  I am no electric expert (at least not electric model propulsion) but something is very wrong with it. As noted by others, something is dragging the armature, the bearings are bad, or the prop is slipping on the shaft. That scraping noise is definitely not normal.

     Brett

[Crist Rigotti]

Check to see if the motor wires are dragging on the case of the rotating part of the motor.

[Ken Culbertson]

Glenn, you can come over anytime, I'm retired. If you live in Northfield near AC it's about an hour drive. If it's a nice day we can fly it in the back yard after we fix it. PM for address.

I also think something is rubbing (maybe a magnet?) so I would take everything apart and look closely for spots.

Or that little washer you couldn't find.  You have to be very careful with the motors on the bench.  They have some pretty strong magnets.
ken

[CircuitFlyer]

Glenn,

On my super clown had to grind down the inside of the motor recess in the fuse to make sure there is clearance to the motor can.  How much end float on your motor shaft?  (Forward and aft play in the shaft). Ideally, there should be very little, maybe .010-.025".  Try a different collet for sure.

Your shaft looks too short (that doesn't sound good).  I use a different motor but I have about a 1/4" of exposed shaft between the front face of the fuse and the back of the collet.

Invest in a servo tester and use it to test run the motor.  It just gives more control while testing out a new system.  Keep the full power runs short and don't overheat anything.

[John Rist]

It's a front mounted motor.  If the mounting screws are too long they can hit something inside the motor.  Probably not the problem but just a thought.  I have never had a good working collet turn loose.  Sounds like you are using a pusher prop.  A sodden  burst in power could loosen the prop nut.  I agree it doesn't sound right.

[John Rist]

What an electric should sound like. 

[TDM]

Here is the deal.
There are metric and inch standard collects for propellers. Sometimes the difference between them is very small. 3mm is .118in which is close to 1/8in .007 is about the thickness of a piece of paper maybe two. s make sure you have a metric or standard shaft and you have the correct adapter for it. Long story short is most motors have metric shafts and when the collet goes on the shaft it should be a nice slip fit with no slop or at most some barely noticeable slop and I mean you almost do not feel it.

[Ken Culbertson]

Here is the deal.
There are metric and inch standard collects for propellers. Sometimes the difference between them is very small. 3mm is .118in which is close to 1/8in .007 is about the thickness of a piece of paper maybe two. s make sure you have a metric or standard shaft and you have the correct adapter for it. Long story short is most motors have metric shafts and when the collet goes on the shaft it should be a nice slip fit with no slop or at most some barely noticeable slop and I mean you almost do not feel it.

I think there are multiple problems at play here.  Listen to that Video - it sounds like somebody put cards in the tire spokes like we did as kids.  W/O a prop my motors make about as much noise as an electric fan.  I do think he has the wrong or a bad collet.  Empathy is in order.  This stuff is quite overwhelming at first, then it gets easier.

Ken

[chris perkins]

Can you mount the motor out of the fuselage on a test mount it would be easier to see what was going on , as has been mentioned before are the securing screws too long ? re.  the prop collet flying off have you tried putting a washer or spacer between the prop and the prop nut to effectively shorten the thread that goes into the nut ?

[Kevin Muckleroy]

When the prop fell off did you notice the can of the motor moves backwards? looks like the motor shaft isn't locked down properly

[Glenn Kirms]

When the prop fell off did you notice the can of the motor moves backwards? looks like the motor shaft isn't locked down properly

I noticed that the entire motor moved backwards.  Without the prop motor seems to run fine though.  Appreciate the reply.

[Glenn Kirms]

I think there are multiple problems at play here.  Listen to that Video - it sounds like somebody put cards in the tire spokes like we did as kids.  W/O a prop my motors make about as much noise as an electric fan.  I do think he has the wrong or a bad collet.  Empathy is in order.  This stuff is quite overwhelming at first, then it gets easier.

Ken

@ Ken - Someone here lives nearby so when I get a free day we will hook up and figure out this frustrating problem.  Being new to electric and all that is being thrown at me here, wouldn't even know the next step.  So, I'll wait for now.

[TDM]

After the prop flies away i hear a big noise in the motor. You might have multiple problems that happen simultaneously. For sure there is something bad with the prop adapter. Second there is some sound in the video after the prop+adapter decide to check out and depart. Definitely a knocking sound during the spool up.

[Ken Culbertson]

After the prop flies away i hear a big noise in the motor. You might have multiple problems that happen simultaneously. For sure there is something bad with the prop adapter. Second there is some sound in the video after the prop+adapter decide to check out and depart. Definitely a knocking sound during the spool up.

You know more than I do about these motors but do you think there is anything the motor itself can do to shed the prop if the adapter is on securely?  This has to be multiple problems.  Personally, I would just get another motor & prop adapter and move on.

To Glen:
If you build enough, you need a motor and adapter to use for fitting things.  I hosed a Cobra last year when I forgot to check for crap in the motor and it found that 2/56 nut I had been looking for.  Now it serves me as the companion to the ESC that got fried when I hooked a battery up backwards.  I don't have to be careful now when I test fit stuff - it is already fried!.  Now I know why the guy I got my basic intro from kept evreything in plastic bags - magnets.  Whenever I have a usable motor on my bench for anything other than final installation, it is either in a plastic bag or I have taped the openings.

The point I am making is that we all go through making a lot of stupid mistakes when we switch to electric.  But, we are used to high cost IC components and what we forget is that individually the components are not very expensive and they are rarely fixable at our level.  So just replace them and move on. I have learned with electric to wait for a sale and order 2 of everything.

Collets are particularly weird.  I would get another one then put it in your box as soon as it proves good then get another one to use.  Right now I am running 4 motors.  All are 5mm and my collets don't all work on all of the motors.  Some tighten easily, others require stealth tactics.  Mostly it is the spinners that make them difficult to tighten.  It is not something you can put into words but you do need to learn how to sneak up on them.  Once it grabs a little you can tighten it really tight but if you go for tight from the start you are just going to keep spinning.

You are doing the right thing to get some experienced hands on help.  Please let us know what you find out.  This is how we all learn.

Ken

[phil c]

I think there are multiple problems at play here.  Listen to that Video - it sounds like somebody put cards in the tire spokes like we did as kids.  W/O a prop my motors make about as much noise as an electric fan.  I do think he has the wrong or a bad collet.  Empathy is in order.  This stuff is quite overwhelming at first, then it gets easier.

Ken

Totally agree.  There is something seriously wrong, most likely with the motor.  It should make nothing more than a smooth whirring sound.  If the collet is poorly made it could be grabbing the shaft in one spot, but still have enough clearance to allow the prop to rock and vibrate.  Or the shaft can be bent.

I'd suggest taking the motor out of the plane and mounting it behind a sheet of quarter inch plywood held in a vise.  But first, get several different collets, preferably from another supplier, and a spare shaft or two.  See if you can mount a collet solidly on the correct size shaft.  If that works, then mount the motor, add the collet , and see if you can start it with a very slow ramp speed and a low rpm.  If you know an RC-er see if they can help by using a receiver to directly run the  speed control a get a softer, smoother start.

With a good motor, a good shaft, and a good collet at full speed all, 10,000 rpm or so, you will hear is some slight, high hum from the bearings, a lower pitch hum from the magnets/can, and nothing else.

[Steve Helmick]

While I'm not even an electric enthusiast, I have been around a bunch of them and seen a lot of guys have various problems. Based on these observations, it seems to me that the motor is rubbing on the fuselage or the prop is rubbing on the front of the fuselage, making the noise. When the prop is being tightened, the collet and stuff pulls back toward the nose of the fuselage, which is an unfortunate design flaw (IMO), but something y'all seem stuck with, and something you'll need to learn to deal with. As a retired machinist, I worked with collets for decades, but how they are used is quite different. They can still bite one in the butt.

The collet itself also seems to be a problem. Not really up on collet sizes, but I could see there being a 5mm and a 5.5mm collet available for different sizes of motors and it would be easy enough for a 5.5mm collet to be mixed up with a bunch of 5mm collets and our OP just got "lucky" and won the wrong collet. The extra .5mm would be close to .020" oversize and certainly enough to make it fail to tighten and grip adequately.    Steve

[Stuntflyn]

Lot's of good suggestions already.

Collets are funny and hard to deal with. A tip I use when tightening a collet is to shove my finger into the motor compartment and wedge it between the fuselage side and the outer case of the motor (on an outrunner). Just turn the motor until your finger gets wedged in there a bit. This will hold the outer case of the motor while you tighten the collet. In my experience, it really does not take much pressure to tighten the collet. Your wedged finger will move as you tighten, so once you have snugged the collet up to the shaft, it really can't go much further before it is plenty tight - it's already touching the motor shaft. Do too much and you WILL over tighten the collet and then you are hosed (ask me how I know .

In your case, the outer case of the motor is right there, just grab a hold of it with your thumb and finger and tighten the spinner and collet until you can't pull the collet and prop off. This is plenty tight. If they still come flying off when you run the motor, you have other issues. Better yet, take the motor out and try this same technique. Holding the outer case, slowly tighten the prop and collet until you cannot pull them off the shaft. This will show you how little tightening is required once the collet is snug to the shaft. If you can still pull the prop and collet off, make sure your prop is not keeping the collet from properly tightening as Dennis mentioned. Collets are made to "bottom out" - in other words, the collet should extend as far as possible onto the shaft. A small amount of "not bottoming out" (maybe for needed prop clearance), generally won't hurt you, but if you are not close enough to bottoming out, you can set up a wicked vibration.

The second item I would check are the mounting screws coming through your firewall. While your motor is out, measure very exactly the thickness of your mounting firewall (in case you were a bit overzealous sanding it). Carefully run the mounting screws into the motor case to see how far they extend into the case. Deduct for the thickness of your firewall. If the screws are too long, they can hit/rub the armature and lot's of bad things can happen from there. Could have a rub which induces a lot of vibration. Vibration is not your friend The screws can be flush on the inside of the motor case, but you really don't want them extending into the armature area.

Your motor appears to be a 400 size of the Chinese variety, so it would not be totally unheard of to just have a lemon. I order some of these directly from China for our "First Flight Training" aircraft. I get the motor, mount and speed control for $6.38. Try another motor and collet if nothing else works.

If you have already over tightened the collet the first time you put it on, it could be hosed - don't be afraid to get another collet.

Sounds like you made sure the motor and prop are not rubbing the aircraft, but do as others have said, double check for possible foreign parts and make sure none of your wiring is touching the motor once it starts up.

We have faith - you'll get it figured out.

[Ken Culbertson]

Your motor appears to be a 400 size of the Chinese variety, so it would not be totally unheard of to just have a lemon. I order some of these directly from China for our "First Flight Training" aircraft. I get the motor, mount and speed control for $6.38.

I was a machinist in my youth (Steve - sometimes I wish I had stayed one) but you are right on.  I always order 2 of anything machined.  You never know when someone fat fingered the mic.   He may very well have an undersized shaft or an oversized hole in the collet or the wrong angle on the hub or maybe even all three.  To think that parts that do not pass QC (assuming they have QC) get out the door in China is pure fantasy.

Where do you order these motors for that price?  I have a couple of kids about ready to give it a try and I need something disposable.  Is there a source for cheap timers as well?  We fly by a large soccer facility and it is not unusual to get a bunch of kids wandering over to watch us.  I would love to have a "first timer" in the back of the car "just in case".

Ken

[Tim Wescott]

Where do you order these motors for that price?  I have a couple of kids about ready to give it a try and I need something disposable.  Is there a source for cheap timers as well?  We fly by a large soccer facility and it is not unusual to get a bunch of kids wandering over to watch us.  I would love to have a "first timer" in the back of the car "just in case".

Ken

HobbyKing, HobbyPartz, MaxxProd -- more or less in order of price.

FirstTimer for the first timer?  Igor Burger makes them -- you might want to ask him.  I could design you one, but my life is not currently arranged to make them up.  Brodak has a bunch of Hubin timers for about $25, which is a fair price for the volumes that sell -- basically, if you could sell 10000 of 'em, you could cost-reduce a Hubin (or KR) timer to about $5 or $10 -- but that's not going to happen.