HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Jul 19, 2012, 07:38 PM
Registered User
Cypress Texas
Joined Dec 2007
403 Posts
Yet another brush less question

I have read about half the posts and come to the conclusion that the ideal brushless motor for the Minimag is .............Lots of suggestions with no clear favorite!. I do I intend to put floats on later and so was thinking maybe the Turnigy 2217 16turn 1050kv 23A motor on an 8 or 9 inch prop would do the trick with 800-900 grmas thrust on 3s. (preference 8 for clearance) and 2200 3S.

Present build has a Emax 2822 1300 kv on it mounted out front with an 8040 prop not flown yet but the power to weight looks OK with no floats but not sure it has the grunt for floats? Using this I could get away with a 1300 battery as opposed to the 2200 on the larger motor.

Would love to mount inside the nose but the inrunners suggested all run the small props and that is not for me, too buzzy.

Since the motor will in inevitably get a dunking at some time prefer to stay with the budget motors Turnigy, ,Emax etc

Any and all comments appreciated..
CaptPJB is offline Find More Posts by CaptPJB
Last edited by CaptPJB; Jul 19, 2012 at 08:20 PM. Reason: Added Emax KV
Reply With Quote
Sign up now
to remove ads between posts
Old Jul 20, 2012, 01:50 PM
Heli's rule!
dacaur's Avatar
Midvale, Utah, USA
Joined Mar 2005
8,624 Posts
From what I can see about that motor (Emax 2822 1300kv) It will be great on your minimag, even with floats....
dacaur is offline Find More Posts by dacaur
Reply With Quote
Old Jul 20, 2012, 05:44 PM
Registered User
dk31's Avatar
Athens
Joined Oct 2009
727 Posts
Quote:
Originally Posted by dacaur View Post
Yea that motor is a bit heavy, but then, so is the stock brushed motor.... I would want something a bit lighter if I were buying it, but if thats what I had on hand, I would probably use it.... 950kv is bit low IMO, but with a 9x6 or 9x7 on a 3 cell I think the plane would fly fine with plenty of power.... the 1800mah battery should work fine too... I fly mine on a 2000mah 3 cell... my motor is half the weight of yours, but its also mounted out in front of the nose.... I dont think you will have any difficulty balancing it as long as you get the motor inside the nose
Unfortunately, the motor has to be mounted in front of the nose; The motor mount has been custom-restored and the nose is full of wood and epoxy...
Also the plane has custom-made permanent floats and it might be already heavier than average.
Anyway, I will bench test the motor tommorow and report back the figures along with the AUW so you could maybe give an opinion

thanks
dk
dk31 is offline Find More Posts by dk31
Reply With Quote
Old Jul 21, 2012, 02:38 PM
Registered User
dk31's Avatar
Athens
Joined Oct 2009
727 Posts
Tested the motor today. Setup was
-turnigy 2836/9 950kV
-CC Ice 50A ESC
-1800mAh 3S 25C nanotech (new)
-9x6 prop

max outcome was 670gr of thrust at 14Amps/155watts

All up weight is 800grams. Sounds a little heavy for such a small plane ?
dk31 is offline Find More Posts by dk31
Reply With Quote
Old Jul 21, 2012, 03:25 PM
Heli's rule!
dacaur's Avatar
Midvale, Utah, USA
Joined Mar 2005
8,624 Posts
Quote:
Originally Posted by dk31 View Post
Tested the motor today. Setup was
-turnigy 2836/9 950kV
-CC Ice 50A ESC
-1800mAh 3S 25C nanotech (new)
-9x6 prop

max outcome was 670gr of thrust at 14Amps/155watts

All up weight is 800grams. Sounds a little heavy for such a small plane ?
Thats not terrible... My AUW is 629 with the battery, 448 without it. Which is about 1.5 oz over the "stock" weight. (Mine is RET right now, no ailerons)

Compared to mine you have a bigger motor (+30g) bigger ESC (+30g), I assume it has ailerons (+30-40g) And floats, which im sure add a few ounces too. You battery according to the specs I can find is .1oz heavier than mine, probably due to thicker wires.... take out the 3 extra ounces that your motor, ESC and aileron servos/hardware weigh, and its only 3 ounces heavier... not bad for a plane with floats and a nose full of wood and epoxy... mine is painted with krylon shotcuts paint, which Im sure adds a few ounces....
dacaur is offline Find More Posts by dacaur
Reply With Quote
Old Jul 21, 2012, 10:25 PM
Pro Bro # 2398
GassPasser's Avatar
BoonVegas, Indiana
Joined Dec 2005
674 Posts
Quote:
Originally Posted by JCMorgan View Post
I have a RxR minimag NIB I could be talked into letting go of for $60 plus shipping if anyone is interested. Might also consider trades.
i;ll take it please.
GassPasser is offline Find More Posts by GassPasser
Reply With Quote
Old Jul 22, 2012, 01:41 AM
Registered User
dk31's Avatar
Athens
Joined Oct 2009
727 Posts
Quote:
Originally Posted by dacaur View Post
Thats not terrible... My AUW is 629 with the battery, 448 without it. Which is about 1.5 oz over the "stock" weight. (Mine is RET right now, no ailerons)

Compared to mine you have a bigger motor (+30g) bigger ESC (+30g), I assume it has ailerons (+30-40g) And floats, which im sure add a few ounces too. You battery according to the specs I can find is .1oz heavier than mine, probably due to thicker wires.... take out the 3 extra ounces that your motor, ESC and aileron servos/hardware weigh, and its only 3 ounces heavier... not bad for a plane with floats and a nose full of wood and epoxy... mine is painted with krylon shotcuts paint, which Im sure adds a few ounces....
I forgot to say that the CC ice ESC is only for testing - the plane has another ESC (can't see the specs as it has velcro and heatshrink all over, but it's smaller).
Battery is 145gr (5.1oz) and it has ailerons.
Thanks for helping out.
I will give it a try with this setup, and if it proves to be weak, i will then try a 9x7 prop
dk31 is offline Find More Posts by dk31
Reply With Quote
Old Jul 23, 2012, 03:31 PM
Registered User
mike_o's Avatar
Denmark, kbh
Joined Jan 2012
1,393 Posts
Quote:
Originally Posted by dk31 View Post
,,,
All up weight is 800grams. Sounds a little heavy for such a small plane?
Mine is 430gr AUW (without wheels). 90W 2822 outrunner, 4 servos, and a 1300mAh 3S LiPo...
mike_o is offline Find More Posts by mike_o
Reply With Quote
Old Jul 23, 2012, 04:07 PM
Registered User
dk31's Avatar
Athens
Joined Oct 2009
727 Posts
thanks for the info. I guess i d have to split mine in half to reach your AUW
You fly it without weels (hand-launch /belly landing)? Is this your choice or because of lack of airfield or spares?
If mine proves unflyable i could strip the floats and follow your way...
dk31 is offline Find More Posts by dk31
Reply With Quote
Old Jul 25, 2012, 10:19 PM
gravity is strong where I fly
Air Cooled's Avatar
United States, NY, Rochester
Joined Jul 2011
220 Posts
Can someone please tell me what the "velco mod" is that you do to this plane, and why?
Sorry to ask, but 285 pages is a lot of reading
Air Cooled is offline Find More Posts by Air Cooled
Reply With Quote
Old Jul 25, 2012, 11:58 PM
Heli's rule!
dacaur's Avatar
Midvale, Utah, USA
Joined Mar 2005
8,624 Posts
Quote:
Originally Posted by Air Cooled View Post
Can someone please tell me what the "velco mod" is that you do to this plane, and why?
Sorry to ask, but 285 pages is a lot of reading
You get some self adhesive velcro and stick it under the trailing edge of the wing (or non-self adhesive and glue it).
The benefit is twofold in that it lowers the angle of attack of the wing which gets rid of some of the ballooning you experience when you overpower the plane with brushless, and it also makes the wing mount a little more secure....

Search function, try it, you will like it, rather than have to wait for an answer or read 285 pages.....
dacaur is offline Find More Posts by dacaur
Reply With Quote
Old Jul 27, 2012, 02:51 PM
Registered User
United States, TX, Richardson
Joined Oct 2011
301 Posts
Fine-tuning my 2nd MiniMag

I added ailerons to my first MiniMag and everything went downhill from there. It got so squirrely that even a pro flyer could barely handle it. The motor mount area needs some major reconstruction, so I just set it aside for a while.

So I built up a 2nd MiniMag and this one is going to stay as a 3-channel flyer. Here is what I have at this point.
  • Stock except that I bought and installed the Multiplex Power Pack which included a Himax 2815-2000 brushless Inrunner, 5.5 x 4.5 APC Prop and MULTIcont BL-17 ESC.
  • I replaced the stock wheels with DuBro 3 inch Micro Sport wheels which weigh 11 grams each. The stock wheels weigh 2.5 grams each. So I added a net weight of 17 grams. (the 3 inch wheels allow me to ROG off a soccer field whereas there is no way with the stock wheels)
  • Total weight with 2S 1300 Lipo is 586 grams. (yes, that is going to sound like too small a battery to most of you, but at my age 5 min of flight time is just fine. I don't need to keep it flying for 20 min or so)
I tested my MiniMag2 this morning first with a 2S battery then a 3S battery. With the 2S battery it was a bit sluggish on takeoff, but once in the air flew very nicely with plenty of power for what I want to do. With the 3S battery it was SUPER hot and a bit scary to fly. It took off like a bat-outta-hell at only half-throttle, then climbed almost out of sight. I had to cut the throttle completely and let it glide down. (the throttle was very sensitive right near the bottom so it was hard to determine how much power I was giving it) It came down nicely in the glide and landed ok.

Here's my thinking, and my question. For THIS version of MiniMag, 3-chan, I just want a lazy, slow flying plane, so I've decided to go with a 2S battery. As I said a bit earlier, once in the air it flies just fine with the 2S battery. But I would like a little more thrust for take off on a grassy soccer field.

Question: Can I get the additional thrust by changing my current 5.5 x 4.5 prop to a 6 x 4, 6 x 5.5e, 7 x 4, or a 7 x 5 prop? A poster earlier in this forum stated that his favorite combo for the Himax 2815-2000 was a 7 x 5 prop. But that combo would draw 20.5 amps, considerably over the upgrade 17 amp max ESC.

I'm thinking of replacing the ESC with a 25A unit, then going with the 7 x 5 prop. (I like the 7 inch prop because it looks better too - smile) Would that be a wise choice, and if not what do YOU recommend? TIA

Gus, in sunny Dallas where it is currently 102 degrees F, 39.1 C in the shade!
fotoflyer is offline Find More Posts by fotoflyer
Reply With Quote
Old Jul 27, 2012, 03:27 PM
Registered User
United States
Joined Apr 2012
1,081 Posts
Quote:
Originally Posted by dacaur View Post
You get some self adhesive Velcro and stick it under the trailing edge of the wing (or non-self adhesive and glue it).
The benefit is twofold in that it lowers the angle of attack of the wing which gets rid of some of the ballooning you experience when you overpower the plane with brushless, and it also makes the wing mount a little more secure....
.
I found this did nothing but curl up the edge a bit if it's too close to the edge of the wing. I ended up moving the Velcro (used 2 pieces) as far in under the wing on the frame as I could go with it where the foam of the wing is a bit thicker. This finally lifted the wing. The single screw on the wing design is weak. May add another to make the wing a bit more secure. The brushless motor puts a little more stress on things then they were designed to handle.
JCMorgan is offline Find More Posts by JCMorgan
Reply With Quote
Old Jul 27, 2012, 03:44 PM
Heli's rule!
dacaur's Avatar
Midvale, Utah, USA
Joined Mar 2005
8,624 Posts
Quote:
Originally Posted by fotoflyer View Post
Here's my thinking, and my question. For THIS version of MiniMag, 3-chan, I just want a lazy, slow flying plane, so I've decided to go with a 2S battery. As I said a bit earlier, once in the air it flies just fine with the 2S battery. But I would like a little more thrust for take off on a grassy soccer field.

Question: Can I get the additional thrust by changing my current 5.5 x 4.5 prop to a 6 x 4, 6 x 5.5e, 7 x 4, or a 7 x 5 prop? A poster earlier in this forum stated that his favorite combo for the Himax 2815-2000 was a 7 x 5 prop. But that combo would draw 20.5 amps, considerably over the upgrade 17 amp max ESC.

I'm thinking of replacing the ESC with a 25A unit, then going with the 7 x 5 prop. (I like the 7 inch prop because it looks better too - smile) Would that be a wise choice, and if not what do YOU recommend? TIA

Gus, in sunny Dallas where it is currently 102 degrees F, 39.1 C in the shade!
Any changes are going to affect amp draw. If you go to a bigger diameter and higher pitch speed prop, you are going to affect amp draw twice. If the top speed is higher than you need, then you can get additional thrust for takeoff without significantly affecting amp draw by increasing diameter and lowering pitch speed. A 6x4 might be just the ticket. Amps might go up a bit, but not a huge amount. You are basicaly just trading top speed for thrust. You might also try a 7x4, which is going to trade a bit more top speed for a bit more thrust, but will also increase amp draw, but not as much as the 7x5 so you might be able to use your current ESC.
dacaur is offline Find More Posts by dacaur
Reply With Quote
Old Jul 27, 2012, 08:53 PM
Registered User
United States, TX, Richardson
Joined Oct 2011
301 Posts
Thank you, dacaur. That makes sense to me. I'm not interested in top speed on this MiniMag so dropping the speed a bit to get more thrust is exactly what I want. I'll get a 6 x 4 prop and see how it works.

How do you guys measure the amp draw? Do you use a special cable hooked up between the battery and the ESC? The red wire in this "amp read" cable would be open with two test points to connect an ammeter in series with the battery-to-ESC cable.
fotoflyer is offline Find More Posts by fotoflyer
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Skycat from Multiplex RArch Foamies (Kits) 143 Nov 20, 2002 06:01 PM
White Shark from Multiplex Jurgen Heilig Foamies (Kits) 19 May 14, 2002 02:36 PM
Not Just New Pictures, but New TJs from MULTIPLEX James Frolik Foamies (Kits) 0 Feb 02, 2002 03:50 PM
Warning: check postage rates when ordering from Multiplex!! crazythumbs Vendor Talk 5 Jul 13, 2001 11:31 PM
Warning: check postage rates when ordering from Multiplex!! crazythumbs Foamies (Kits) 1 Jul 09, 2001 08:52 PM