Ok guys, next project.

I have a Brodak Vector 40 that I built from a kit in 2006.  It has a OSLA40 engine in it and I have never really been ultra happy with this motor.  At first I had problems with run-away, so I tamed it down, but then it seemed under powered and rather inconsistent. The model currently weighs 49oz wet. It flies well and is still in good gondition but has always been let down by inconsistent motor runs, hence it spends a lot of time not being flown.

I am now planning to UPGRADE it to electric power.

I know I will use a Castle ICE LITE 50 and Hubin FM2-R timer. At the moment I am considering which motor I will use. My options are:

Turnigy 3542D-1000kV Eq AXI 2820
Turnigy 3548-900kV Eq AXI 2826
Arrowind 2820-07 (aka Brodak EPS40)
Arrowind 2826-06
Scorpion SII 3020 920kV

The battery will be whatever is required, but I would like some feedback on which motor you all think would be the best for this setup. I'm leaning towards the Turnigy 3542 because I like the way the prop drive is done and cheap at around $20US but I am concerned about it being under powered.

With the Arrowind and the Scorpion, obviously price is a concern and I'm not really a fan of the way their props attach.

Regards,
Warren

Archie,
Are you recommending the ICE 50 or the ICE 50 lite on this one?
John

Ice 50 Lite is all that is required.  As Alan has pointed out before, the Heat Sink is for the BEC that we really don't use enough power on to make any difference.  I bought the Ice 50's with Heat sink as I am using 6S on my CLPA bird and the weight wasn't really an issue to me.  I could have used the lite without issues on it as well.

Archie Adamisin
Muncie, Indiana 

HobbyKing has 2 different 'versions' of some of their motors -

The gold/chrome ones are the "C" versions.

The Black/chrome ones are the "SK" versions - larger shafts (in some models - not the 3542 however), improved bearings and possibly improved magnets.  I have flown a C3548 and an SK3548 in the same plane and would not have known the difference from the flying.  The SK version is slightly heavier and in the 3548 model, very slightly longer.  For some reason, in the 3548 size, their site shows the SK as being colored gold/chrome also, but we've never gotten anything but black ones, and in our club there are at least a dozen of them flying.

(There is a rumor on the HobbyKing forum that "SK" stands for "Scorpion Killer" - a couple of years ago there was a rather heated debate on their forums concerning the quality of Scorpion motors vs. the Turnigy line.  Led to the banning of the US Scorpion dealer from their forums.  Having flown both, I can say that while the Turnigy is good for the price, Scorpion has nothing to worry about.). 

Warren,

For the difference in cost, I prefer the SK series as I feel they are better built.  I have a 35-42-1100 Gold Series and a 35-42-1000 SK. I have run both.  I will be using the gold series in my new Classic bird and the SK in another classic bird that will follow.  Both motors run very closely and from the handle and even with a data logger, I doubt you will see much of a difference.  

The Scorpion motors I have seen are very nicely built and run very good.  Crist, Alan, and Will have been very successful with them.  I prefer Turnigy as I now own stock in them. I have the following:

(1) 28-36-1200Kv (Red & Blue series)
(1) 35-42-1100Kv ("C" series Gold & Chrome)
(1) 35-42-1000Kv SK
(2) 35-42-1250Kv SK
(1) 35-48-1100Kv SK
(1) 42-40-1050Kv (Purple motor)
(1) 42-50-650Kv SK


The (2) 35-42-1250's are for R/C EF-1 Pylon Racers, but the rest are dedicated ECL motors.  The Vector 40 will work well with either 35-42 motor.

Archie Adamisin
Muncie, Indiana  

Thanks guys for the excellent feedback.  I think since one is only $17 and the other is $20 I might be able to afford to buy one of each and try them both!  I might convert another model as well!    

Cheers

I am surprised, I thought the scorpion has lower resistance ... I think axi has 40mohm, while sc has 30 if I remember numbers well. Also no load current is lower at sc, I think by 0.1A so it should have better efficiency, but you are right, real values are exactly the same, on 6sA123 they have both input power 335W on stand with APC 12x4 at 9100rpm, while AXI 2826/10 (kv=920, ri=28, i0=2.2) needs 370W and AXI 2826/13 needs 330W (kv=680, ri=42, i0=1.4)

however the same axi 2826/10 needs only 340W instead of 370W if used on 4 lipos :-)

 ... I am still somehow confused what parameters to look for to find best efficiency under load at 80-90% PWM

It is also a little tricky relying on motor winding resistance, because in actuality, you need to also consider the ESC. But I was just a "little" surprised that they were so close. If I look at the values on "DriveCalc", where someone (not me) has entered some actual measurements of these two motors under load, the "effective" resistance is a lot closer to each other.

But I suppose the motors are similar because the Scorpion 3020 has a wider diameter stator which must offset at least some of the extra length of the AXI 2826. That's my guess anyway!

Flew the Vector today. Had 3 excellent flights. Awesome. 9500 rpm is what I guessed and it's right on the money, using about 1800mAH of a 2650mAH battery.  I'm going to add a little nose weight though as it's just a tiny bit twitchy.  More flights tomorrow...

Dennis,

I think it's pretty much a given that I am a convert for F2B.  I want all my F2B models to have electric right now!  As for Classic Stunt, well they will stay as glow engines and my Sig Twistang with the Saito 30, it will never change.

I'm going to focus on flying the Vector now for our State Champs in June. The Vector had a OS LA40 which I was never really happy with.  Seemed to run fine here by the water at sea level, but as soon as I took it somewhere inland it would misbehave.

Bruce and I were flying together today and will be again tomorrow... we are the F2B electric trail blazers of Oz lol

I was watching Bruce's model today flying with a APC 13 x4.5 Pusher now... it flies so slow yet powerful, he's doing something like 5.8 second laps now, he had to extend the flight time to finish the pattern. I was standing about 6 feet away from the circle and could feel the prop wash as he turned near me.  So much thrust!

It was so impressive, even the radio control guys were coming over and asking us questions about our electric setup.

Cheers

Warren

Well, I am pretty sure that your motor will run pretty much the same no matter where you fly it - so THAT problem should be solved.  ALso, I re-read the thread and saw where you said you flew it at 49 oz with the LA40.  If your conversion is only 1 oz more than I'd say you did pretty good.

The LA40 is a pretty heavy engine, so I'll bet your CG is aft of where it used to be.  Still Dorin's advice might save you any more extra weight.

My Vector revision got pushed aside by other projects, but I plan on cutting windows into the rear fuse sides, replacing the heavy fin, and sanding some cubes off the stab.  Collectively that should all help, in its first iteration this Vector was a wee bit tail heavy for me.

Hi Guys

I added 1/2 oz in the nose and have moved the leadouts back slightly today an had 3 really good flights with it.  It flew better than yesterday and is doing 5.3 sec laps.  I'll keep playing with it and I'm sure I will get it really good.  In the past with the IC engine I spent all my time trying to get the motor running right. Now I can focus on getting it to fly right as well as improving my flying ability.

Bruce's model is flying really nice too.  Here's a pic showing where we were flying.

Edit: tonight I removed the weights and replaced them with a battery safety Y cable thingo.  One thing I did notice tonight also, that I used more power today. Yesterday I used 1800mah, today I used 2100maH the only things that changed was the 1/2 oz of nose weight and I increased the Governor gain.  What did it? The 1/2oz weight gain, the governor gain change or both?

Cheers

I doubt the 1/2 oz had any effect, more likely the goverrnor gain AND less wind.  No wind conditions tend to turn up the power usage.  Where are you on the gov gain setting?  Did it make a difference flying?

I'm with Dennis 100%!
More ponies where you need it leads to more battery consumption.
Even hitting harder corners leads to more consumption.
Dean P.