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Old Sep 22, 2003, 09:00 AM
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Zwolle, Netherlands
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Which brushless power system for FVK Optima XXL

Hi there,

As I am very pleased with my FVK Optima XXL I am planning on replacing the power system with a more efficient brushless outfit in due time. Although I already checked several options (AXI, Kontronik) I am very interested in your opinions, as I have no experience with the brushless power.

I now use:
- LRP 550 7-8BB motor
- MPJet 3,8:1 gearbox
- Aeronaut 15x10" Carbon Prop
- Kontronik SUN4001 ESC
- 8x SANYO RC3300HV
which gives it a climb-rate of about 3-4m/s. I'd like just a bit more but I am not interested in hotliner-like performance as the plane is not designed for it. My main reasons for considering brushless are more efficiency and less wear 'n tear.

The Optima XXL is a 2,2m wingspan thermal glider w/ ailerons, flying weight is about 1600g, it has a separate nose-cone with limited space (40mm spinner). See also http://www.fvk.de/Englisch/Optima%20XXL.html for more details.

Thanks,


Martijn
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Old Sep 22, 2003, 01:41 PM
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Jyvaskyla, Finland
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AXI 2820/10 is ok with 7-8cells. Use propellers like 12x8, 13x7-8, 14x8 (max). Graupner 13x7 and 7 cells is slightly less than 30 amps. Torcman 280-20 would be even better. Even economy LRK brushless motors are superior to their conventional counterparts.

Take a look at the new Flyware innenlaufer 650 series. Another good alternative!

BTW How did your Optima XXL balance with 2 servos in tail? I am just finishing mine with AXI in the nose.
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Old Sep 23, 2003, 04:07 AM
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Hi Tuomo,

First of all, welcome at this forum, I guess we're both newbies!!

The AXI 2820-10 seems like a good option, also because I wouldn't like to draw much more than 30A out of the RC330HV's. Why would the Torcman 280-20 be better b.t.w? I'll check out the Flyware innenlaufer 650.

As for the balance: the fuse seems to get rather tail-heavy if the servo's are put in the tail but I preferred the direct linkage. So I put both HS85BB/MG's (22g each) in the tail. With my motor and gearbox (I guess about 225g) the cellpack lies in the fuse with 1/3 sticking out in the nose-cone.

Your AXI has less weight, so you might get in trouble. I am aware I put pretty heavy servo's in the tail to start with, so it might be wise to consider lighter options. I guess it also depends on which and how many cells you use, the cellpack I use is 8 subC's and weighs about 500g, which gives ample weight for trimming.

Congrats with your Optima XXL by the way, it's an outstanding thermal glider!! Did you also get the floater nose-cone with it??


Martijn
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Old Sep 23, 2003, 04:55 AM
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Hi Martijn, if I remember correctly, user 'Kimble Schmitz' (Jos Mouris, http://members.lycos.nl/JosMouris/index.html) lives near Zwolle, he uses Flyware lrk's in his sailplanes. You can search for his posts.

off_topic:
Are you familiar with http://www.modelbouwforum.nl/ ?

Met vriendelijke groet Ron van Sommeren
diy outrunner brushless e-motor discussion.
Electric fly-in & lrk meet, June 27th, 2004, Nijmegen, the Netherlands.
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Old Sep 23, 2003, 05:31 AM
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Thanx Ron, I will do a search on 'Kimble Schmitz's posts.

*****of topic*****
En, ik ken inderdaad modelbouwforum.nl maar ik heb er nooit gepost en ben er al een tijdje niet geweest... Zal ik weer eens doen! Bedankt voor je tips, groeten en vliegze, Martijn
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Old Sep 23, 2003, 07:08 AM
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Quote:
Originally posted by Vinkie
As for the balance: the fuse seems to get rather tail-heavy if the servo's are put in the tail but I preferred the direct linkage. So I put both HS85BB/MG's (22g each) in the tail. With my motor and gearbox (I guess about 225g) the cellpack lies in the fuse with 1/3 sticking out in the nose-cone.

Your AXI has less weight, so you might get in trouble...
Thanks for the warning. I think I will put only the elevator servo in tail.

Take a look at this one: http://www.flyware.de/pd546762901.htm?categoryId=13

Flyware LRK motors do not fit in, nor does Torcman 350 series, but the new innenlaufers are only 40mm diameter. The 650 F5 weights 240g -- should help nicely if you have a problem with CG!
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Old Sep 23, 2003, 07:52 AM
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Torcman (Flyware too?) has shaft extension assemblies for narrow noses.

Groeten Ron

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Old Sep 23, 2003, 08:56 AM
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Ron, I tried to fit Torcman 350 with extension shaft to Optima XXL nose. It is a very tight fit. I do not know if it is worth the trouble in a plane of this size? There are more compact motors that will do the job just as well: Torcman 280-20, AXI 2820/10 and Flyware 650 F5 etc.
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Old Sep 23, 2003, 09:19 AM
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Hi again,

Ron: bedankt voor de tip!!

Tuomo: I checked your link and the MAX650-series seems to suit my purposes very well. I figure the MAX650-F5/10x6" prop would be good, I also considered the MAX650-F6/14x9,5" but I am not sure about drawing 34A from Sanyo RC3300HV's. What do you think? Maybe the F6 is a bit overblown for the Optima XXL ?

Regarding the CG-issue: I didn't mean to put you of placing both servo's in the tail, I sure wouldn't trust a bowden link with this size of rudder and the large deflections. As the manual states I'd do some testing with the parts taped where you'd like them, to see if you can get correct CG. Maybe lower weight servo's would help rectify matters, and I guess there's no harm in putting the battery deep in the nose-cone, as long as it doesn't interfere with the motor, right?

If I can help just let me know, Kind regards,

Martijn
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Old Sep 23, 2003, 09:47 AM
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Hi, I think you are a bit on the conservative side. 12x6 would be my choise with the 650 F5. 30A with 7 cells, 36A with 8 cells.

This table is very useful
http://www.flyware.de/download/Antri...elleMAX650.pdf
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Old Sep 23, 2003, 10:02 AM
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Hi Tuomo, I picked my options out of the table you suggested in your previous post, so yes, I must be very conservative However will the RC3300HV's handle 36A? I thought they were only meant to go up to about 30A and they are NiMH's. If they were the NiCad RC2400's I'd wouldn't hesitate to frie the #@%$ out of 'em but in this case I'm not so sure.
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Old Sep 23, 2003, 10:17 AM
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Vinkie, sorry I do not know much about RC3300HVs. Do they get warm at 30A? Perhaps someone will help as with this problem??

It seems that Flyware 650-F5 allows higher amps than AXI 2820/10. AXI's max is about 40 amps -- I would not take more out of it -- but Flyware seems to tolerate 45A even according to manufacturers specs

Here is a link to AXI motor test. It is Swedish but might still be helpful to you:
http://www.mft.nu/elmotortest/
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Old Sep 23, 2003, 10:45 AM
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Tuomo, thanx for the (again) useful link. I know Sweden isn't THAT far from here but I assure you Swedish doesn't even closely resemble Dutch, although my unintelligable remarks to Ron might make you think otherwise. Luckily the Swedish do count in the metric system

I run the cells at about 24A in my current setup, and they don't seem to heat up much in flight. Then again I always manage to stay up for 50 minutes at least so I don't really know. Time to roll out the testbench I guess. Anyone else have experience with RC3300HV's???

Martijn
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Old Sep 23, 2003, 01:57 PM
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My experience with the AXI is that it is a great motor for a sport sailplane up to 50 oz. - if the motor fits in the nose. With 7 cells I have used mine at 40 amps with no problems turning a 16X10 prop ( I fly at over one mile asl). Closer to sea level people are using 14X9.5 props with no problems and approx the same amps being drawn. If one uses Sanyo HR-4/5AUP there is plenty of power with less weight.

Mike
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Old Aug 18, 2004, 06:40 AM
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do you know Io
for Flyware MAX 650 F5
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