Wattflyer RC Network: RC Universe :: RCU Magazine :: RCU Forums :: RCU Classifieds :: RCU User Reviews :: RCU YouTube
Home Who's Online Calendar Today's Posts RealTime Post Spy Mark Forums Read
Go Back   WattFlyer RC Electric Flight Forums - Discuss radio control eflight > R/C Electric Power - Batteries, Chargers, ESCs and More > Power Systems
Register Members List Wattflyer Extras Articles Search Today's Posts Mark Forums Read Social Groups

Power Systems Talk about motors, ESC speed controllers, gear drives, propellers, power system simulators and all power system related topics

Thank you for your support (hide ads)
Reply
 
Thread Tools Display Modes
Old 01-10-2012, 07:01 PM   #1
trike_flyer
New Member
 
Join Date: Jan 2012
Location: Leduc, AB, Canada
Posts: 14
Thanked 0 Times in 0 Posts
iTrader: (0)
Friends: (0)
Default Gear drive to brushless direct

Hello all

I am switching from a speed 280 with a 4:1 gear ratio to a direct drive brushless on a new kit I just got. I figured it was better to do the change right away rather than after I got it built so there is no extra holes to fill in the firewall. The plane also is available with a speed 300 and has a claimed weight of 14 oz.

From the charts I have seen, a 1000-1100kv motor is recommended for the swap. I have been looking and have chosen the mystery 2208-17 1100kv and a 30A mystery ecs for it. I chose the motor as it is suppose to draw only 8A full load and the esc at 30A for extra padding in case it draws more than the published amount with the prop I want to use. The kit came with a 3 blade 9 1/4" prop, pitch is unknown, so I was figuring a 9-10" x 5" pitch to try for starters.

The question is did I oversize the esc too much or is it a safe way to go? I can change it to a 20A and still have a safe margin. There are four types of mystery brand esc in the 20A and 30A size, red,blue,yellow cloud and yellow petium. Is there any one better than the other? Has anyone tried this motor with a prop of this size? Is it safe to use the kv rating of the motors as a way to substitute them from maker to maker?


Thanks for the info and help in this matter.

TF
trike_flyer is offline  
  Reply With Quote
Old 01-10-2012, 09:29 PM   #2
pmullen503
Member
 
Join Date: Mar 2011
Posts: 875
Thanked 75 Times in 74 Posts
Awards Showcase

Scratchbuilders Award 
iTrader: (0)
Friends: (3)
Default

Originally Posted by trike_flyer View Post
Hello all

I am switching from a speed 280 with a 4:1 gear ratio to a direct drive brushless on a new kit I just got. I figured it was better to do the change right away rather than after I got it built so there is no extra holes to fill in the firewall. The plane also is available with a speed 300 and has a claimed weight of 14 oz.

From the charts I have seen, a 1000-1100kv motor is recommended for the swap. I have been looking and have chosen the mystery 2208-17 1100kv and a 30A mystery ecs for it. I chose the motor as it is suppose to draw only 8A full load and the esc at 30A for extra padding in case it draws more than the published amount with the prop I want to use. The kit came with a 3 blade 9 1/4" prop, pitch is unknown, so I was figuring a 9-10" x 5" pitch to try for starters.

The question is did I oversize the esc too much or is it a safe way to go? I can change it to a 20A and still have a safe margin. There are four types of mystery brand esc in the 20A and 30A size, red,blue,yellow cloud and yellow petium. Is there any one better than the other? Has anyone tried this motor with a prop of this size? Is it safe to use the kv rating of the motors as a way to substitute them from maker to maker?


Thanks for the info and help in this matter.

TF
KV has to be considered with the voltage of your battery. The motor and prop you've chosen is appropiate for a 3s lipo. For a 2s lipo you would want more like 1500-1800 KV.

Headsup RC has a good guide to selecting a brushless motor

Your 30A ESC is oversized which isn't a problem except that it'll be heavier than you need.

It's never too late to have a happy childhood.
pmullen503 is offline  
  Reply With Quote
Old 01-10-2012, 10:48 PM   #3
Dr Kiwi
Super Contributor
 
Join Date: Aug 2005
Posts: 1,726
Thanked 180 Times in 174 Posts
Awards Showcase

Outstanding Contributor Award 
iTrader: (0)
Friends: (3)
Default

That 2208-17 is probably the same as the Suppo 2208-17 I tested some time ago... on 3s an 8x4 GWS HD will draw <8A yet get you >17oz thrust @ 37mph... plenty for a 14oz plane. A 12A-15A ESC would do you well enough... but a 20A Pentium would be fine too.

On 2s you could use 9x5 GWS HD or 10x6 GWS HD (draws almost the same as the 10x5 APC E I tested it with).


Attached Thumbnails
Click image for larger version

Name:	Todds-Suppo-Welgard A2208.17 (1100Kv).jpg
Views:	145
Size:	292.0 KB
ID:	156267  
Dr Kiwi is offline  
  Reply With Quote
Old 01-11-2012, 12:23 AM   #4
trike_flyer
New Member
 
Join Date: Jan 2012
Location: Leduc, AB, Canada
Posts: 14
Thanked 0 Times in 0 Posts
iTrader: (0)
Friends: (0)
Default

Thanks for the reply guys.

I chose a 30A esc because I can get one for less than the 20A where I was planning to buy and the 3g weight differance is not worth concern to me. The bec on the 30A is an amp higher if I need it and it leaves room for a motor upsize if need. As a newer flyer I expect to crash it and will have parts for the next model that will be good for a larger model.

From what I gather the blue or yellow pentium are both good. The blue and from looking around the black, that makes 5 types they sell out there, are the newer ones they make. I am leaning toward the blue one because it allows you to switch between 8 and 16 khz. I am getting the impression from other flyers that running on 16khz is better for the motors.

Thanks for confirming the motor choice.

TF
trike_flyer is offline  
  Reply With Quote
Old 01-13-2012, 12:39 AM   #5
trike_flyer
New Member
 
Join Date: Jan 2012
Location: Leduc, AB, Canada
Posts: 14
Thanked 0 Times in 0 Posts
iTrader: (0)
Friends: (0)
Default Thrust between the two

Hello all

Found a site that said the gear drive 280 will only give me about 6-9 oz of thrust. From the chart dr kiwi supplied, the motor I chose can beat that hands down with the 8" prop. Since I plan to go lipo for the battery I should get a lighter plane overall with more thrust.

Talking about the chart, What happens to the amps when the plane moves. The chart is after all a static motor test, bolted to the bench. So when the plane moves the prop loading is lower. Will I get more rpm or lower amps or both?

Thanks guys

TF
trike_flyer is offline  
  Reply With Quote
Old 01-13-2012, 10:00 PM   #6
pmullen503
Member
 
Join Date: Mar 2011
Posts: 875
Thanked 75 Times in 74 Posts
Awards Showcase

Scratchbuilders Award 
iTrader: (0)
Friends: (3)
Default

Originally Posted by trike_flyer View Post
Hello all

Found a site that said the gear drive 280 will only give me about 6-9 oz of thrust. From the chart dr kiwi supplied, the motor I chose can beat that hands down with the 8" prop. Since I plan to go lipo for the battery I should get a lighter plane overall with more thrust.

Talking about the chart, What happens to the amps when the plane moves. The chart is after all a static motor test, bolted to the bench. So when the plane moves the prop loading is lower. Will I get more rpm or lower amps or both?

Thanks guys

TF
Amps will drop. Because you will get a small increase in battery voltage at lower amp draw, the RPM will slightly increase as well. Unlike IC engines, RPM is determined by voltage and KV, not airspeed or load.

It's never too late to have a happy childhood.
pmullen503 is offline  
  Reply With Quote
Old 01-14-2012, 01:49 AM   #7
Dr Kiwi
Super Contributor
 
Join Date: Aug 2005
Posts: 1,726
Thanked 180 Times in 174 Posts
Awards Showcase

Outstanding Contributor Award 
iTrader: (0)
Friends: (3)
Default

Unlike IC engines, RPM is determined by voltage and KV, not airspeed or load.

I can't agree with that.....increasing the load (= prop size) will obviously decrease RPM.. especially if your motor is too small.....RPM as a % of Kv x V diminishes as the motor becomes loaded (or over-loaded)... load it up with a monster prop.. it will bog down and eventually stall... RPM = 0.

If you had said "no-load RPM is determined by voltage and KV"... then I would tend to agree.... but even then, for each particular motor, there will be modifying factors, such as mechanical friction, wire resistance, magnet strength....

Airspeed does factor in too... certain props "unload" in flight more than others.
Dr Kiwi is offline  
  Reply With Quote
Old 03-26-2012, 04:02 PM   #8
trike_flyer
New Member
 
Join Date: Jan 2012
Location: Leduc, AB, Canada
Posts: 14
Thanked 0 Times in 0 Posts
iTrader: (0)
Friends: (0)
Default Got the parts

Hello all

Well I finally got all the parts I needed to do the switch to a brushless. Have been doing bench tests on the setup. The motors I got are RC timer, fellow flyer was selling box of five so I grabbed them. Got the mystery blue esc in 30a as I wanted and a nano tech 2200mah battery in 3s. The prop so far is a 8X4.3 that I am using.

On the bench I have got about 17.5-19 oz of thrust from the set up. For some reason the motors are not exactly the same. Could be from the way they are wound. Found out that the oversize esc gives you the benafit of a lower resistance, which increases your current flow. Same for battery size and type. Larger battery = lower resistance. Seems the nano tech battery has a lower resistance than a normal Lipo since my current is higher than what ecalc said it should be. Should drop while flying and I do not plan to fly wot all the time. Half throttle is about 9-10 oz of thrust, which will fly the model around easily I think and has a nice low current draw. Think it was about 4 amps, wot is 8.5A on the bench. I put all the parts that need to go in the model inside it and put it on the scale. It came out at about 17 oz, which tells me I can hang it on the prop I got. I switched the esc to 16khz pwm and it made the motor run quieter and the amp draw went down 0.25 amps.

One question that comes up is did I oversize the battery?

Ecalc said at wot I will get a 15 min run time. I won't be at wot for more than take off for most flights. Does anyone have an idea of what to expect for flight times? Or do I have to fly it till the battery is out to get an idea? I was told 15 min is about the most you want to fly a model. Something to do with if you fly longer it gets harder to keep it in control.

Thanks for the help.

TF
trike_flyer is offline  
  Reply With Quote
Reply

  WattFlyer RC Electric Flight Forums - Discuss radio control eflight > R/C Electric Power - Batteries, Chargers, ESCs and More > Power Systems

« Previous Thread | Next Thread »

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

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 On

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Everything You Wanted To Know About Electric Powered Flight AEAJR Beginners 154 10-20-2014 03:46 PM
Everything You Wanted To Know About Electric Powered Flight AEAJR General Electric Discussions 269 06-27-2014 02:06 PM
The New GWS SLOW STICK tallflyer ParkFlyers 615 01-18-2013 05:20 AM
MSR carbon rod reinforced landing gear + permanent 250mAh Li-Po holder Thewyzardofdogz E-Flite Helicopters 1 03-19-2011 07:52 AM
For Sale Brand NEW ElectriFly T-400GD ESC Motor System with Gear Drive with ESC bah7566 Motors and Speed Controllers for sale & WTB 3 02-27-2011 01:07 PM


All times are GMT +1. The time now is 12:22 PM.


Powered by: vBulletin
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright 2005 WattfFlyer.com
RCU Eflight HQ

Charities we support Select: Yorkie Rescue  ::  Crohn's & Colitis Foundation



Page generated in 0.24853 seconds with 36 queries