HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Feb 22, 2013, 01:00 PM
Registered User
Centerville, In. USA
Joined Jul 2001
1,965 Posts
Discussion
motor speed wavering

I just about have a little indoor 85 gram trainer type plane done.The problem is when I test run the motor, the servos start jerking around and the motor speed goes up and down on its own. What causes that to happen. Is it the rx, esc, or motor likely causing the fluxuating? RCNutt
rcnutt is offline Find More Posts by rcnutt
Reply With Quote
Sign up now
to remove ads between posts
Old Feb 22, 2013, 02:13 PM
Registered User
Staffs, UK
Joined Nov 2003
10,258 Posts
Quote:
Originally Posted by rcnutt View Post
Is it the rx, esc, or motor likely causing the fluxuating?
Yep probably one of them, or maybe the battery. And if you tell us a little about what rx, esc, and motor you're using we might even be able to guess which one it is .

Steve
slipstick is offline Find More Posts by slipstick
Reply With Quote
Old Feb 22, 2013, 08:16 PM
Registered User
Centerville, In. USA
Joined Jul 2001
1,965 Posts
OK sorry about the time break. I've got a part time job I had to go to. The receiver is a Corona from BP. I found it would not work with my newer computer Tx. It has been working alright with my really old 72 mhz Tx. The battery pack is a 2s lipo 240 mah and It is brand new. The esc is a 6 amp Turnigy from Hobby King also new. The motor is a tiny 3+ gram brushless from Hobby King.The prop vibrates kind of bad and it is a 5-3 from Hobby King. I just now checked the balance of 2 5x3 props from Hobby King and they were way out of balance, so maybe this is the problem. I tried a 4x2.5 prop that I didn't buy from from Hobby King and it seemed to work just fine. Maybe a good quality prop will cure the problem of fluxuating motor speed and and jittery servos. Any thoughts? RCNutt
rcnutt is offline Find More Posts by rcnutt
Reply With Quote
Old Feb 22, 2013, 08:20 PM
The Last Question
United States, UT, West Valley City
Joined Oct 2006
531 Posts
Prop imbalance shouldn't affect other components. A balanced prop is essential but maybe you have a loose connection or short.
Entropy76 is online now Find More Posts by Entropy76
Reply With Quote
Old Feb 22, 2013, 08:31 PM
Registered User
Centerville, In. USA
Joined Jul 2001
1,965 Posts
I guess it is possible that I did not get good solder joints in my 2 cell lipo pack. Some types of tabs on the lipo batteries don't like to be soldered. Maybe I should disassemble my pack and check the connections. Thanx for your thoughts. RCNutt
rcnutt is offline Find More Posts by rcnutt
Reply With Quote
Old Feb 22, 2013, 09:50 PM
Registered User
West of California Speedway, East of LaLa, North of Disneyland
Joined May 2001
2,234 Posts
Quote:
Originally Posted by rcnutt View Post
I ...................Some types of tabs on the lipo batteries don't like to be soldered. ............................. RCNutt
Some LiPo's have solderable tabs on one side (probably nickel plated), and the other side aluminum. Darn near impossible to solder to Al, but with the proper solder, I have done it.
356Jim is offline Find More Posts by 356Jim
Reply With Quote
Old Feb 22, 2013, 10:28 PM
M16 CIII/AR15/FN 2000 and PS90
Denile's Avatar
United States, AR, Waldron
Joined Jan 2005
521 Posts
Which 3gr motor are you using, I cannot imagine an motor in the 3gr range turning a 5-3 prop as most in that weight will be high Kv; high current might be an issue.
Denile is offline Find More Posts by Denile
Reply With Quote
Old Feb 23, 2013, 05:46 AM
Registered User
Centerville, In. USA
Joined Jul 2001
1,965 Posts
Your are right. I must have forgotten. the weight is 6.4 grams which to me is still remarkably small for a commercially availible motor. The max continuous amp draw is where the "3" number came from. It is called a HD1610 3400 KV F3P. I was thinking about connections and may be that it is my battery to esc connector. I used 2/3rds an old servo connector. I have some tiny bullett connectors I will solder on instead of the servo connector. But for sure I will not use the HK 5x3 props. I don't think I could sand off enough material to make them balance. They are bad! RCNutt
rcnutt is offline Find More Posts by rcnutt
Reply With Quote
Old Feb 23, 2013, 05:57 AM
Registered User
CorvetteC5's Avatar
Kokomo, Indiana
Joined Jun 2008
847 Posts
Balancing a prop this size and power is easily done by adding a bit of clear scotch type tape to the light tip.
CorvetteC5 is offline Find More Posts by CorvetteC5
Reply With Quote
Old Feb 23, 2013, 10:51 AM
miataman
miatamama's Avatar
Erie Pa.
Joined Oct 2007
663 Posts
Rc, If the 4x2.5 prop works it tells me the prop is to big or your new batt is a bit weak.
try cutting down a 5x3 and see what happens.
When you get it sorted out let us know what the problem was.

JCS
miatamama is offline Find More Posts by miatamama
Reply With Quote
Old Feb 23, 2013, 02:35 PM
Registered User
Centerville, In. USA
Joined Jul 2001
1,965 Posts
I did the tape method to balance the prop. It took 3 full length pieces of scotch tape to balance it. I tried it again and afterthat and I get to about 2/3 throttle when the wavering and jittering starts ! The lipos are new and rated at 240 mah 20 C . I tried to get an amp reading but it is all over the place but it doesn't seem to be more than 3 amps. The battery should handle that OK. I could try to replace the connectors that go to the battery but I kind of doubt that it would make any difference.The 5x3 is the prop of choice according to the guys that have written in on the Hobby King forum reviews and they use just 2 cells.. What might I try next? Any more ideas? RCNutt
rcnutt is offline Find More Posts by rcnutt
Reply With Quote
Old Feb 23, 2013, 03:59 PM
If it flies - I want one!
Petem's Avatar
Werribee, Victoria, Australia
Joined Jul 2008
998 Posts
Try with no prop?

RCNutt,
Try running the system without a prop? If it runs up happily with no load to full throttle, the most likely suspect is excessive prop load. Sneak up on prop size till you hit the sweet spot.
Cheers,
PeteM
Petem is offline Find More Posts by Petem
Reply With Quote
Old Feb 23, 2013, 06:13 PM
Registered User
Centerville, In. USA
Joined Jul 2001
1,965 Posts
I know in the larger sizes of GWS props they offer a slo-fly and a DD type prop. Is that true also of the 5" GWS props or are they all the same type in the 5" size? RCNutt
rcnutt is offline Find More Posts by rcnutt
Reply With Quote
Old Feb 23, 2013, 06:14 PM
Registered User
Centerville, In. USA
Joined Jul 2001
1,965 Posts
I was thinking that when the airplane is in the air it would unload some. I may try the 5-3 prop once anyhow. RCNutt
rcnutt is offline Find More Posts by rcnutt
Reply With Quote
Old Feb 23, 2013, 08:30 PM
M16 CIII/AR15/FN 2000 and PS90
Denile's Avatar
United States, AR, Waldron
Joined Jan 2005
521 Posts
You might want to try an 4-2.5 first or as petem suggested no prop although I would recomend some load. Don't count on prop unloading during flight as the current drop is minor.
Denile is offline Find More Posts by Denile
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
For Sale C20 Pro 2050KV Brushless Motor, 12 Amp Speed Control, 3mm Prop Adapter $25 Shipped solarr Aircraft - Electric - Power Systems (FS/W) 1 Jan 14, 2013 01:04 PM
For Sale New Viper Kit, Motor & Speed Control $60 shipped solarr Aircraft - Electric - Airplanes (FS/W) 0 Jan 09, 2013 12:11 AM
For Sale New PushyCat Canard Kit, Motor & Speed Control $60 shipped solarr Aircraft - Electric - Airplanes (FS/W) 0 Jan 09, 2013 12:08 AM
For Sale New F-86 Kit, Motor & Speed Control $60 shipped solarr Aircraft - Electric - Airplanes (FS/W) 0 Jan 09, 2013 12:05 AM
Discussion What causes motor waver? rcnutt Power Systems 5 Oct 12, 2006 06:30 AM