Notices
Electric Pattern Aircraft Discuss epowered pattern aircraft in this forum

Mystery knocking noise?

Old 04-18-2010, 11:53 AM
  #1  
2Sunny
Thread Starter
 
Join Date: Oct 2005
Location: pound ridge, NY
Posts: 608
Likes: 0
Received 0 Likes on 0 Posts
Default Mystery knocking noise?

I have heard about a "knocking" noise that occassionally appears, and today while practicing I definitely heard it. Its not unlike a car that is experiencing a pre-detonation problem and gets that knocking sound when you accelerate or go up hill. It stopped when I changed the data logging on my Castle HV 80 back to 1 Hz.

Has anyone else experienced this or something like it?

Does anyone know what is actually making the sound?

Could it be harmful to the motor?




In any case, like I said it went away when I changed the sampling rate.


As always, thanks for any input.






Joe
Old 04-18-2010, 03:58 PM
  #2  
iflyrctoo
Senior Member
 
Join Date: Sep 2002
Location: Great Bend, KS
Posts: 136
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Mystery knocking noise?

It sounds like the controller may be missing a few output cycles while it updates the memory cache in the logger. I ran my HV80/Pletty up without a prop and could hear a slight ticking sound.

Just a guess.

Joe Dunnaway
Old 05-12-2010, 09:11 AM
  #3  
Jetdesign
My Feedback: (8)
 
Jetdesign's Avatar
 
Join Date: May 2008
Location: Honolulu, HI
Posts: 7,056
Received 0 Likes on 0 Posts
Default RE: Mystery knocking noise?

I think I may be experiencing the same phenomenon. I noticed a 'tick' or a 'knock' at full throttle climbing vertically. I was mystified as the frequency of the knocking was much slower than anything spinning in the plane, but now that you talk about sampling rate, it may have been occurring at the sampling rate of my data logging ESC.

I guess I'll try changing the sampling rate but would love to hear if anyone has more detail on this issue.
Old 05-12-2010, 09:16 AM
  #4  
Chris Moon
My Feedback: (8)
 
Chris Moon's Avatar
 
Join Date: Dec 2002
Location: Leesburg, VA
Posts: 1,366
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Mystery knocking noise?

I was told by the Castle rep at Toledo that they are aware of this and that reducing the sample rate will minimize it or fix it and turning off the logging if you don't use it will fix it until they have a firmware upgrade for the issue.
Old 05-12-2010, 09:27 AM
  #5  
can773
My Feedback: (1)
 
can773's Avatar
 
Join Date: Jan 2002
Location: Calgary, AB, CANADA
Posts: 2,286
Likes: 0
Received 2 Likes on 2 Posts
Default RE: Mystery knocking noise?


ORIGINAL: iflyrctoo

It sounds like the controller may be missing a few output cycles while it updates the memory cache in the logger. I ran my HV80/Pletty up without a prop and could hear a slight ticking sound.

Just a guess.

Joe Dunnaway
Joe, please do not run a Pletty without a load (prop), it could possibly damage the motor. This is probably true for any motor!
Old 05-12-2010, 09:44 AM
  #6  
Jetdesign
My Feedback: (8)
 
Jetdesign's Avatar
 
Join Date: May 2008
Location: Honolulu, HI
Posts: 7,056
Received 0 Likes on 0 Posts
Default RE: Mystery knocking noise?

Thanks ual.
Old 05-12-2010, 04:29 PM
  #7  
Jason Arnold
 
Jason Arnold's Avatar
 
Join Date: Aug 2005
Location: Sydney, AUSTRALIA
Posts: 1,341
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Mystery knocking noise?

G'day Chad,

I don't understand how running an "electric" motor without a prop could possibly damage it...[&:]
I use AXI and I'm sure they(or Jeti) recommend setting things up i.e. your ESC without the prop fitted for safety reasons.

Current drawn without a load is only a few amps so over current damage is not a factor IMHO.

Looking forward to your explanation.

Cheers
Jason.
Old 05-12-2010, 08:22 PM
  #8  
iflyrctoo
Senior Member
 
Join Date: Sep 2002
Location: Great Bend, KS
Posts: 136
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Mystery knocking noise?

Chad,
I'm wondering what kind of damage this would cause too? I had my watt meter inline and total load was only 350 watts at full throttle.
I work with electric induction motors and frequency drives where I work and it's very common to test the drives and motors uncoupled from the load.

Thanks Chad

Joe
Old 05-12-2010, 08:25 PM
  #9  
can773
My Feedback: (1)
 
can773's Avatar
 
Join Date: Jan 2002
Location: Calgary, AB, CANADA
Posts: 2,286
Likes: 0
Received 2 Likes on 2 Posts
Default RE: Mystery knocking noise?

Overspeed, and it states it in all Plettenberg instructions "do not run with no load".

Whats the point of running without a prop? If its to run with low amps, then simply use a 5s pack rather than 10s, you will only get 1/2 the load. Or better yet 3s, for even less amps!
Old 05-12-2010, 08:42 PM
  #10  
iflyrctoo
Senior Member
 
Join Date: Sep 2002
Location: Great Bend, KS
Posts: 136
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Mystery knocking noise?

Ok, I was setting up my speed controller on the bench and didn't want everything in my shop blown all over the place. This is my first electric and I'm still in the learning phase.

Thanks Chad

Joe
Old 05-12-2010, 08:46 PM
  #11  
Jason Arnold
 
Jason Arnold's Avatar
 
Join Date: Aug 2005
Location: Sydney, AUSTRALIA
Posts: 1,341
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Mystery knocking noise?


ORIGINAL: can773

Overspeed, and it states it in all Plettenberg instructions ''do not run with no load''.

Whats the point of running without a prop? If its to run with low amps, then simply use a 5s pack rather than 10s, you will only get 1/2 the load. Or better yet 3s, for even less amps!
Ok, I'm not sure how overspeed would damage the motor unless it goes way over the Kv rating of the motor and or the bearing rating. I would think the KV rating on most motors is done with no load too. I suspect that heat could be a worry if the motor is run for extended periods without a prop/load.

Whats the point of running without a prop? I run my motor without a prop when setting things up. It's safer. In the past, I have run it up in the garage with the prop on and you'd be amazed at how much crap gets blown all over the place. Won't do that again.... lol

Cheers
Jason.
Old 05-12-2010, 09:07 PM
  #12  
Jason Arnold
 
Jason Arnold's Avatar
 
Join Date: Aug 2005
Location: Sydney, AUSTRALIA
Posts: 1,341
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Mystery knocking noise?

Here we go... From the Plettenberg manual.

"The motors may not be used without load; otherwise you can simply cross the max speed of motor and controller."

I must admit that I've never seen the max speed limit on my Jeti. They may simply be covering themselves incase someone hooks up too many cells. This is where a Kv rating can be misleading to some extent.

Cheers
Jason.
Old 05-12-2010, 10:10 PM
  #13  
Jason Arnold
 
Jason Arnold's Avatar
 
Join Date: Aug 2005
Location: Sydney, AUSTRALIA
Posts: 1,341
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Mystery knocking noise?

It looks like the Jeti can have a maximum and minimum RPM setting in Heli mode. Doesn't seem to have that function for fixed wing acro mode.[&:]

Cheers
Jason.
Old 05-12-2010, 10:12 PM
  #14  
can773
My Feedback: (1)
 
can773's Avatar
 
Join Date: Jan 2002
Location: Calgary, AB, CANADA
Posts: 2,286
Likes: 0
Received 2 Likes on 2 Posts
Default RE: Mystery knocking noise?

Don't know what to say guys! I have ran Pletty's in pattern longer than most anyone, and I follow their instructions and don't run them without a prop. I still fly the prototype 30-10 Evo to this day!

I wasn't trying to argue, just offering up some of my experience.
Old 05-12-2010, 10:47 PM
  #15  
iflyrctoo
Senior Member
 
Join Date: Sep 2002
Location: Great Bend, KS
Posts: 136
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Mystery knocking noise?

No argument from me Chad... I was trying to setup the Castle Speed controller and their instructions recommended doing it without a prop. I missed the warning from Plettenberg. Thanks for pointing it out.

Joe
Old 05-12-2010, 11:12 PM
  #16  
Jason Arnold
 
Jason Arnold's Avatar
 
Join Date: Aug 2005
Location: Sydney, AUSTRALIA
Posts: 1,341
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Mystery knocking noise?

Hey Chad,

I think it's about learning something new not arguing... Sorry if it came across that way.

Plettenberg obviously have a valid reason for their warning. My AXI/Jeti has no such warning hence my curiosity was aroused.[&:]

Personally, I find this forum is a good place to bounce ideas and share experience. Arguably, RC would be way behind the eight ball if it wasn't for this forum..

Cheers
Jason.
Old 05-13-2010, 05:53 PM
  #17  
byoung466
My Feedback: (16)
 
Join Date: Jul 2002
Location: tulsa, OK
Posts: 574
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Mystery knocking noise?

With regard to no load operation I wonder if it's a precaution against tossing the windings by overspeeding. Even though you would think the controller would limit speed.
Old 05-13-2010, 06:18 PM
  #18  
Jason Arnold
 
Jason Arnold's Avatar
 
Join Date: Aug 2005
Location: Sydney, AUSTRALIA
Posts: 1,341
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Mystery knocking noise?

Anything is possible I suppose...

I wouldn't think that centrifugal force would be an issue as the windings are static for in-runners and out-runners. However, one must also consider the induced magnetic force on the windings and permanent force generated by the magnets. I'm unsure if the windings in our motors are infused with lacqure or not to stop windings vibrating or singing which would prevent tossing windings. Looking at my motors, I'd say they're not lacqured and only rely on the winding tension to hold them in place.

Cheers
Jason.
Old 05-13-2010, 09:30 PM
  #19  
Jetdesign
My Feedback: (8)
 
Jetdesign's Avatar
 
Join Date: May 2008
Location: Honolulu, HI
Posts: 7,056
Received 0 Likes on 0 Posts
Default RE: Mystery knocking noise?

FWIW, I got off the phone today with Castle Creations and found my motor timing should be 'low' and PWM should be 8kHz. Of course I also changed the sampling rate but had a very smooth running motor with no strange noises.
Old 09-06-2010, 01:50 AM
  #20  
xrboss
Member
 
Join Date: Apr 2005
Location: Qld, , AUSTRALIA
Posts: 70
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Mystery knocking noise?


ORIGINAL: gaRCfield

FWIW, I got off the phone today with Castle Creations and found my motor timing should be 'low' and PWM should be 8kHz. Of course I also changed the sampling rate but had a very smooth running motor with no strange noises.

I get the knocking sound when ever i turn the data logging on, the sample rate of the data logging seemed to not change the sound. I have a CC Pheonix HV 80

If I turn off the data logging no knocking sound.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell or Share My Personal Information -

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.