Thread Tools
Old Dec 30, 2015, 08:33 PM
Catevari is offline
Find More Posts by Catevari
Registered User
Joined Jun 2012
27 Posts
Discussion
Need some help on SU-47 Lanxiang Kit

Hello all,

Not sure this is the right area to put this, been trying to find one but I may have overlooked, if its the wrong area, I do greatly apologize.

Being said now, I need some help for the aforementioned model; SU-47 Lanxiang Kit

I have a thread in the general section about servos but what I need to also know now is what are good motor brands to get for this thing. I have metal freewing edf cowls and fans, but since I am new I don't know much about the brands of motors out there, the only one I've been able to find for a 70mm EDF running 6s LiPo are Dr. Mad Thrust 2600kv motors. The freewing EDF's are 11 blade metal fans, which I believe it will handle. I just wasn't sure if there is anything better out there for this kit?

Much appreciate any help I can get.

Thanks,
David
Catevari is offline Find More Posts by Catevari
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 30, 2015, 08:40 PM
4stripes is online now
Find More Posts by 4stripes
Registered User
4stripes's Avatar
Canada, ON, Burlington
Joined Jan 2009
6,120 Posts
I'm using Changesun 12 blade fans with cyclone power 2000kv outrunners. They are a package available from Hobby Paradise. They are perfect for a single 6s 5000mah battery.
I've also used them in my LX A10. Very happy with them after dynamically balancing them myself. They were not very well balanced from the factory.
Here is my SU47 thread.
http://www.rccanada.ca/rccforum/showthread.php?t=380866
4stripes is online now Find More Posts by 4stripes
Reply With Quote
Old Dec 30, 2015, 09:09 PM
Catevari is offline
Find More Posts by Catevari
Registered User
Joined Jun 2012
27 Posts
Thanks for the reply 4stripes!

The Freewing EDF cowl and blades I have coming are aluminum and I think I originally said 11 blade, but looking at it says 12. It suggests a 2100-3300kv 28-30mm motor, so will the Cyclone Power 2000kv's work with that or should I get the Dr. Mad Thrust like I originally was looking at?

If you need to look at the Freewing EDF setup, the one I have is listed on ebay here: http://www.ebay.com/itm/321735628074...%3AMEBIDX%3AIT

Also, I bookmarked your build page. Do you really think the hull needs the rods for strengthening? What about the wings?

Alternately, since you pointed me to Hobby-Paradise, I found this motor which is also freewing: http://www.hobby-paradise.com/en/pro...ct_detail.html
Do you think that would be the best choice since it matches the brand of the EDF unit?
Catevari is offline Find More Posts by Catevari
Last edited by Catevari; Dec 30, 2015 at 09:15 PM.
Reply With Quote
Old Dec 30, 2015, 09:16 PM
4stripes is online now
Find More Posts by 4stripes
Registered User
4stripes's Avatar
Canada, ON, Burlington
Joined Jan 2009
6,120 Posts
I think 2000kv is just perfect for 6s in a twin setup. 2600 will create undue stress on the battery,
I'm going to strengthen the wings for sure as I'm cutting out the leading edge flaps to make them operational. The fuse is so easy to strengthen while you build it and will help prevent cracking upon any hard landings. The EPS is pretty thin and brittle, much like the A10.
Those metal fans are more expensive than had you bought the complete fan and motors. Probably heavier too than the plastic but they should be fine with the cyclone power motors which are also available separately.

PS here is my thread on the fan units suggested
http://www.rccanada.ca/rccforum/showthread.php?t=311026
4stripes is online now Find More Posts by 4stripes
Last edited by 4stripes; Dec 30, 2015 at 09:23 PM.
Reply With Quote
Old Dec 30, 2015, 09:26 PM
Catevari is offline
Find More Posts by Catevari
Registered User
Joined Jun 2012
27 Posts
Thank you for the help, I also look forward to how you strengthen the wings.

The reasoning I went with the fans is because the one is counter rotating. I have read a lot of reviews of twin motor jets, including this one in particular, where people said left turns are slower then right, due to the fans rotating in one direction. They sell them as a complete unit for about 190-200$, so I figured what I spent, while slightly above what I've found on websites like Hobby-Paradise (which they do have these there for 100$) will net me something in return through eBay with the eBay bucks thing. Plus it was only 12$ more so not horrible.

I plan on using a 6s 5000mAH battery for this once I get to flying it after I gain experience in my others first, so you think the 2600's will still create a excess stress on the battery running through the suggested 2x 50A ESCs?
Catevari is offline Find More Posts by Catevari
Reply With Quote
Old Dec 30, 2015, 09:26 PM
4stripes is online now
Find More Posts by 4stripes
Registered User
4stripes's Avatar
Canada, ON, Burlington
Joined Jan 2009
6,120 Posts
I wouldn't recommend the 2300kv motor in the link you posted either unless you plan to switch to a 5-6 blade fan.

I've built and flown a number of twins without counter rotating fans, and never had any turning issues or noticed any ill effects at all.
Perhaps if you were planning to hover there may be a slight benefit but usually with TV you have plenty of control and wouldn't need any special compensation for two fans running the same direction.
4stripes is online now Find More Posts by 4stripes
Reply With Quote
Old Dec 30, 2015, 09:30 PM
4stripes is online now
Find More Posts by 4stripes
Registered User
4stripes's Avatar
Canada, ON, Burlington
Joined Jan 2009
6,120 Posts
If you run 2600kv it is way too high a KV rating for 6s using 12 blade fans. You might be OK with 5-6 blade fans.
4stripes is online now Find More Posts by 4stripes
Reply With Quote
Old Dec 30, 2015, 09:37 PM
Catevari is offline
Find More Posts by Catevari
Registered User
Joined Jun 2012
27 Posts
Ah, well, like I said, I just read a lot about the SU-47 snap rolling right due to the rotation, maybe because of the wing design? I've also seen youtube videos of it as well, which is why I thought the counter rotating setup would be better. If not, oh well, I'll just have it either way now.

Looks like going with the 2000kv motors you suggested will save me money in the long run too, versus having bought the edf/fans I have as a whole unit with motors.

Now on the wings, how are you figuring on stiffening them? I know you said you intend to do a little more cutting on them to use the edge flaps, I probably won't do that.
Catevari is offline Find More Posts by Catevari
Reply With Quote
Old Dec 30, 2015, 09:48 PM
4stripes is online now
Find More Posts by 4stripes
Registered User
4stripes's Avatar
Canada, ON, Burlington
Joined Jan 2009
6,120 Posts
I will likely use CF strips set into the underside of the wing. Haven't had time yet to do this, but hopefully soon the thread will see some progress.
My A10 has CF spars added and I plan the same idea for the SU47. Not sure yet how to have a carry through spar joining both wings but it will likely be an arrow shaft going right through the ducts. The ducts are so large it won't affect airflow.
A10 build.
http://www.rccanada.ca/rccforum/showthread.php?t=315890
4stripes is online now Find More Posts by 4stripes
Reply With Quote
Old Dec 30, 2015, 10:03 PM
4stripes is online now
Find More Posts by 4stripes
Registered User
4stripes's Avatar
Canada, ON, Burlington
Joined Jan 2009
6,120 Posts
If fan rotation was playing a part in twin engine aircraft, you would also see an effect in a single fan jet. There simply isn't any effect as the stator vanes straighten the airflow considerably before exiting the shroud. The SU47, two different A10's, ME262 and B737 I've built and flown had no unusual specific wing drop or turning tendencies. In stall testing most could be trimmed to stall straight ahead, but in a couple the wing drop was completely random. Half the time left and half right.

I think many people had issues with the SU47 due to the TV and control setup causing mis-trim or over control.
Care must be taken to reduce the TV and control throws to as little as is needed.
4stripes is online now Find More Posts by 4stripes
Reply With Quote
Old Dec 31, 2015, 09:18 AM
Catevari is offline
Find More Posts by Catevari
Registered User
Joined Jun 2012
27 Posts
I think I understand, either way, will look forward to your thread, and much appreciate the help you have given this newbie. As I said, probably will be a while before I am ready to attempt flying it, but trying to gather everything I need up so when it comes time, I can just sit down and work on it without running around or waiting arrivals.
Catevari is offline Find More Posts by Catevari
Reply With Quote


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
For Sale LX SU-47 Kit - NEW KIT ignernt_dweeb Aircraft - Electric - Airplanes (FS/W) 1 Dec 06, 2015 09:20 AM
Discussion Need some help!! PZ P-47 or PZ Mosquito??? SubyDude Electric Warbirds 2 May 20, 2014 08:32 PM
Cool Lanxiang SU-47 Thrust Vectored SMorrisRC Hot Online Deals 4 Apr 14, 2010 09:25 AM
Discussion Power system for Lanxiang SU 47 Mtn_Commando Foamy EDFs 9 Feb 24, 2010 09:51 AM
Discussion Power system for Lanxiang SU 47 Mtn_Commando Power Systems 1 Jan 18, 2010 08:16 AM