Espritmodel.com Telemetry Radio
Reply
Thread Tools
Old Dec 23, 2013, 03:27 PM
Fly Safe !
Lucke's Avatar
SP, Brazil
Joined Jul 2004
329 Posts
Question
BN-2 Islander plans - new on twins

Hello,

Iīm planning to start this project, so I bought this plans:

http://www.trapletshop.com/gb/p/12033/bn-2b-islander

In the time that the model was build it used a 400 size motor, and now what brushless could be good?

I think on emax 2822 but I donīt know if they are good enought. Some tip?

About the esc, how to use it on twins? Two ESCīs wiht an Y chord on receiver or one ESC?

Thank you in advance!
Lucke is offline Find More Posts by Lucke
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 23, 2013, 04:11 PM
Registered User
Australia, NSW, Harrington Park
Joined Apr 2008
198 Posts
Lucke,
Why not use BRUSHED motors?
Nigel Hawes the columnist in the British RCM&E Special Edition magazine dated Autumn 2013 pages 46 to 49 puts up a good argument for brushed motors particularly in multi-engined park flyers.

The brushed motors are cheap and only need one ESC for twin motors.
Think of the saving when you move up to that four-engined model you possibly plan to build one day!

Regards
Tony

Quote:
Originally Posted by Lucke View Post
Hello,

Iīm planning to start this project, so I bought this plans:

http://www.trapletshop.com/gb/p/12033/bn-2b-islander

In the time that the model was build it used a 400 size motor, and now what brushless could be good?

I think on emax 2822 but I donīt know if they are good enought. Some tip?

About the esc, how to use it on twins? Two ESCīs wiht an Y chord on receiver or one ESC?

Thank you in advance!
aerotony is offline Find More Posts by aerotony
Last edited by aerotony; Dec 24, 2013 at 05:43 AM.
Reply With Quote
Old Dec 23, 2013, 04:44 PM
Balsa Flies Better!
Stamford, CT
Joined Oct 2000
6,704 Posts
Gack-

I wouldn't go to brushed motors any more unless I really needed to- can't get good ESCs.

And yes- you want to use two brushless motors each with its own ESC and a Y-connector.

I'd start with a clean sheet of paper for a power system though- your airplane might come out a lot lighter than the airplane in the article. Being a twin though- the nicad battery may have been needed for noseweight. My last twin wound up needing lead in the snoot for balance using lipoly batteries when it had originally been designed for nicads.

As a guess- if those 2208s are similar to an Axi 2208 and will do around 90-100 watts spinning a 6.5" prop- you'll probably be fine. I've got a thread on a K+A Dinah I'll see if I can link to which should give you some ideas about power systems. http://www.rcgroups.com/forums/showt...n+s+in+kitchen

Sam
Megowcoupe is offline Find More Posts by Megowcoupe
Reply With Quote
Old Dec 23, 2013, 06:34 PM
Fly Safe !
Lucke's Avatar
SP, Brazil
Joined Jul 2004
329 Posts
Thank you!

So I need to use two ESCīs with an Y on battery and channel 3 right?

The motor that Iīm thinking to use is this with an 9" prop.

http://hobbyking.com/hobbyking/store...er_1200kv.html

To ESC, maybe two of this:

http://hobbyking.com/hobbyking/store...hless_ESC.html

Itīs good to use one motor running clockwise and other anticlockwise?
Lucke is offline Find More Posts by Lucke
Last edited by Lucke; Dec 23, 2013 at 06:41 PM.
Reply With Quote
Old Dec 23, 2013, 07:08 PM
Balsa Flies Better!
Stamford, CT
Joined Oct 2000
6,704 Posts
Umm- no. Well-hang on-

Yes to using a Y on the battery to handle both ESCs- although if you're soldering stuff up, you can just put both cables on the plug. I don't know which channel you need- but I've never had a problem with any radio.

In terms of motors though- no. You need something that will turn the prop shown in the plans with about the same amount of watts. This airplane is going to fly a lot faster than a 3D foamie.

Counter rotating props are not necessary- I've flown half a dozen twins and none of them have needed this. Which is good, because it can be really tough to find matching clockwise and counterclockwise props.

I've only used Castle Creations ESCs on twins. These ESCs eliminate the problem of having to disconnect the BEC feature on one because the BEC circuits don't interfere. Other ESCs will probably require you to disconnect the BEC on one (pull the red wire). This to me eliminates an important redundancy feature on a twin- you really want the radio to keep working no matter what.....

Sam
Megowcoupe is offline Find More Posts by Megowcoupe
Reply With Quote
Old Dec 23, 2013, 07:24 PM
Fly Safe !
Lucke's Avatar
SP, Brazil
Joined Jul 2004
329 Posts
This is the problem Sam, the plans donīt talk about the size of props , only that is 400 size motor... other thing that I found on plans, the motors donīt show any angle to right/left or down. Twins donīt have angles on motors?
Lucke is offline Find More Posts by Lucke
Reply With Quote
Old Dec 23, 2013, 08:14 PM
Balsa Flies Better!
Stamford, CT
Joined Oct 2000
6,704 Posts
OK- then I'll stand by my guess- look for around 100-125 watts on a 6-7" prop. I suspect that 125 watts on a 7" prop would have plenty of power on a 1.1 kg airplane. This will have much more performance than the original setup by the way. You wouldn't be doing badly with a 6" prop with 100 watts either.

In terms of thrust lines- twins don't need side thrust- so straight ahead works fine. However- since if you've got a flat bottom airfoil or something similar- twins often need a bunch of downthrust- they don't have much moment arm. I'd guess at 3 degrees. If you've got a semi-symmetrical airfoil- I'd go with about half that-but again I'm guessing.

Sam
Megowcoupe is offline Find More Posts by Megowcoupe
Reply With Quote
Old Dec 24, 2013, 07:47 AM
Fly Safe !
Lucke's Avatar
SP, Brazil
Joined Jul 2004
329 Posts
Thank you Sam,

What about this motors?

http://hobbyking.com/hobbyking/store...tor_100w_.html

Or this:

http://hobbyking.com/hobbyking/store...er_1200kv.html

About the thrust line, is flat bottom airfoil. thanks for the informations.

On ESC I can sold the battery conector and on one of each I have to cut the red wire to disabe tle BEC, . tks
Lucke is offline Find More Posts by Lucke
Reply With Quote
Old Dec 24, 2013, 08:11 AM
Balsa Flies Better!
Stamford, CT
Joined Oct 2000
6,704 Posts
Sorry- but I can't stand Hobby Royalty (hobby king)- I don't trust their specs and in the case of the motor you posted- can't find them. Bear in mind that for a twin- you MUST have reliable motors and ESCs that throttle up identically- otherwise when you're slow and hit the throttle- you'll have an instant snap roll. If you want to use HK stuff, you better get help from somebody else.

Sam
Megowcoupe is offline Find More Posts by Megowcoupe
Reply With Quote
Old Dec 24, 2013, 08:24 AM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
12,783 Posts
Now I love 'cheap', so Hobby King are fine by me and my multies
eflightray is online now Find More Posts by eflightray
Reply With Quote
Old Dec 24, 2013, 08:53 AM
Fly Safe !
Lucke's Avatar
SP, Brazil
Joined Jul 2004
329 Posts
No problem Sam, thank you anyway.

As it is my first trying on twins, Iīm not planning to spend too much, Iīll run better stuff on my second project.
Lucke is offline Find More Posts by Lucke
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion BN-2 Islander - Scratch from Plans.. some questions Lucke Scale Kit/Scratch Built 3 Dec 29, 2009 01:40 PM
New to BN-2 Islander; prop type LareeRudee GWS (Grand Wing Servo) 10 May 29, 2005 11:50 PM
FS- New in box GWS BN-2 Islander, C-20 esc, 2s Etec 1200 lipo, and 2 cell charger. Etonic Aircraft - Electric - Airplanes (FS/W) 2 May 10, 2004 07:33 PM
GWS BN-2 Islander with twin 280 or EDF50! GWS4CEO GWS (Grand Wing Servo) 26 Jul 01, 2003 09:17 AM