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Newbie; power system for H9 Funtana X 50?

Old 11-04-2008, 07:15 PM
  #51  
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Old 11-04-2008, 07:37 PM
  #52  
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I bought this one:
http://www.hobbycity.com/hobbycity/s...idProduct=7638

They are rated at 20C, to 80 amps shouldn't be a problem. I'll discharge - recharge them soon and see what they do. I just did two more measurements:
57,07A at 20,28V
70,54A at 19,01V
That doesn't seem too good, does it, for a 20C pack, regardless of it's charge, does it?

Another thing I noticed, I wanted to make a 50 - 55 - 60 - 65 A test, was the fact that the amps skyrocket after 2/3 throttle. I was somewhere at 40 amps 2/3 throttle, another click was 57 and another click was 70. Nothing inbetween. Is there some way I can set my Futaba T7C to a more linear throttle response? (I know, wrong forum, but in case anyone knows...)

Cheers,

Hugo
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Old 11-04-2008, 07:44 PM
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Old 11-05-2008, 09:21 AM
  #54  
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I just set some negative percentage of expo on the throttle, but I think (in retrospect) the power delivery was pretty linear, but with the voltage going down, amps will go up faster to maintain constant power increase. I believe the ESC is revving up a constant RPM/s, linear with the throttle, but the voltage drop together with inefficiency increasing with power delivered, together this made the weird amp-curve relative to the constant throttle movement. The smaller prop would aid in making this problem smaller, too, I think.

BTW, I'm considering charging the lipos outside, under the overhang of the barn roof (out of the rain). It's about 10 degrees C, here (50F?), that's OK, right?
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Old 11-05-2008, 05:46 PM
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Old 11-05-2008, 05:49 PM
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Old 11-05-2008, 07:12 PM
  #57  
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Originally Posted by ministeve2003 View Post
... they'll be fine charging them anywhere inside...

Thanks, but I've seen just too many pics of burnt-out vehicles and hobby-sheds to do it inside. Call me chicken, but I prefer safe over sorry in this case. Discharge is happening as we speak. Charging at 4A means it's done in an hour, right? Good. More info later tonight (it's 19.12h here, now).

Hugo
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Old 11-05-2008, 07:17 PM
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Old 11-05-2008, 09:55 PM
  #59  
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http://www.modelbouwforum.nl/forums/...-uit-nooo.html

Posted a week ago, new LiPo, high quality charger, bad luck...
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Old 11-06-2008, 10:01 PM
  #60  
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Well, fully discharged - recharged a pack today, it took 3972mAh before the charger said it was done. Less then 1% under target. For the price, not too bad. Hopefully the smaller props come in tomorrow, I'll do some load tests with them on this fully charged pack.

And I dailed in some negative expo on the throttle (15%) which makes start-up a little better (I could go 3 clicks on the throttle without the prop starting to turn) and makes a more level amp-increase.

Hugo
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Old 11-06-2008, 10:13 PM
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Old 11-07-2008, 11:51 AM
  #62  
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Originally Posted by ministeve2003 View Post
I can't understand the language on that forum, does it say what brand lipo and charger...
Oy, you're not fluent in Dutch, then? Weird... I am! (probably has something to do with the fact that I'm Dutch.) Brand of LiPo and charger were not mentioned, but it was all brand new stuff and the guy is an experienced electro flyer. Stupid of him to leave the stuff unwatched, I think.

Anyway, I've made a nice metal charging booth that resides under the overhang of the barn roof. Better safe then sorry.

Now let's hope the props come in today! I've taken the afternoon off to do many things at home today, I can probably find the time for a test or two.

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Old 11-07-2008, 05:38 PM
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Old 11-11-2008, 07:18 PM
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Well, today the props arrived. Hooked up to the Watt's Up, I did a 5 second burst with each:

Prop 16x8 Xoar Beechwood
V min 21.27V
I max 84.87A
P max 1818.7W

Prop 15x8 Xoar Beechwood
V min 21.34V
I max 70.08A
P max 1538.1W

Pack was fully charged. I think I'll start out with the smallest, this seems safe and I think power will be sufficient, to say the least. Oh, and the wooden props are 22 grams for the 16" and 27 grams for the 15" lighter then the el cheapo plastic 16x10 I had on there for the first test.

One wing is done, second is in the middle of modification, now I need to focus on fitting the pack in the fuse in some light and force-distributing manner.

Cheers,

Hugo
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Old 02-27-2009, 08:02 AM
  #65  
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Finally, after a lot of different projects in between, it flew! It's a perfect plane, power galore, I love it! Here's 2 bad quality clips (I have to learn how to use my new camera) of the maiden, done my my instructor and Funtana X50 pilot Hans:





Unfortunately, some magnets came loose on the third flight, so the motor will be soaked in actone for a few days and the magnets re-glued with UH Endfest. But, I'm totally happy with the plane. Only one problem; I just bought a second Funtana, a crash/half rebuild project of a EMHW Funtana S. Yep, that will be 2 meters span, 4.5 - 5 kilos! I think I'll take the motor out of our washer/dryer for that...

Hugo
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Old 02-27-2009, 02:55 PM
  #66  
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Congrats on the maiden. If you're looking for another motor try a Scorpion 4025-12. Got one for my 2 test prototype 6s planes. Designed to take the heat with high temp windings and magnets. They have a 2 year warranty as well. Have fun and keep 'em flyin'!
http://www.innov8tivedesigns.com/pro...45305c8d6be3f1

Greetz,
Jason
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Old 02-27-2009, 08:23 PM
  #67  
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Thanks. I haven't opened the motor, yet, and I'll give the reglue a try, first. Also I'm going to power-down it a bit. Static I now have 1500W on 2,5 kg, which is 'plenty', but I think it takes the motor out of it's comfort zone. It now runs a 15*8 prop, I have a 13*10 lying here which will go on after the motor repair, just to try. If that can still pull me out of a hover that's enough. And I hardly ever hover anyway. I was just advised at the LHS that 350W/kg is plenty for 3D, so I should aim for 900 Watts in flight power. That would be only 40-ish amps on 6S, meaning a) the pack would last longer and b) the motor is more efficient (it looses efficiency rapidly as the current goes up).

Hugo
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Old 02-28-2009, 02:10 AM
  #68  
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HugoW
As for re-gluing the magnets, you might want to try an old (Very Old) modeling trick with CA. Rough up the "bell" with a thin strip of sand paper, clean it up with pure alcohol, then stick the magnet in place with thin CA. Then after this sets, fill in the space inbetween the magnets with plain old Baking Soda. Be certain to verify that NO baking soda sticks above the surface of the magnets.

Then, place a drop or two of the CA over the baking soda, making certain that all baking soda has been wetted with CA. Don't dump the CA on, just verify that none of the baking soda has been missed.

Now, try to remove this baking soda/CA stuff! Its nearly as hard as concrete, and even better, it resists high temperatures.

Try this stunt on something none-critical before using it on your motor. Once applied, you will find it difficult to remove.

Good Lucik!
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Old 02-28-2009, 02:56 AM
  #69  
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Here's a pro tip from the maker of Grim Reaper Motors:
http://www.rcgroups.com/forums/showt...29375&page=171
Also may not solve the problem if the magnets are hitting the stator from the can flexing too much.

Jason
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Old 02-28-2009, 04:11 AM
  #70  
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EDFRules
Good Point!!!
That's why I like the Hacker A40 and larger series motors (or any similar design motors) The far end of the magnet bell is supported by a large diameter ball bearing. The outside of this bearing is attached to the Inside Diameter of the magnet "bell" with several screws. The ID of this bearing is supported by the stationary stator part of the motor.

It is not possible for the Hacker magnet bells to "flex" and hit the magnets since the large diameter ball bearing absolutely prevents this from happening. The manual for these A40 and larger Hacker motors indicate they have FOUR ball bearings.

Sure, the Hacker and similar motors with this large diameter ball bearing cost more, but then they really work very well. I've got two Hacker A40 series motors, two Hacker A50 series, and one Hacker A30 series motor. The A30 series does not have the large diameter ball bearing. I run the A40 and A50 motors at 50-60 Amps full throttle with zero problems. This current drops to 20-30 Amperes average during flight. Of course I've got these motors VERY well ventilated with a direct blast of air from the front of the model. NO spinners are used, just a machined tapered prop nut made on my lathe.

I ran into the magnets hitting the stator with the GoBrushless motors, with the triple stack windings.
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Old 02-28-2009, 07:55 AM
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Thanks guys for the tips. I've bought UHU Endfest 300 to glue the magnets that came loose. It will be hardened at 50 degrees C in an oven for 3 hours, making it very strong. That glue was recommended by some highly experienced Germans who make their own motors. In the league of Hacker and Strecker. The glue can take up to 200 degrees C before loosing strength, at that point the magnets already have lost their power.

This is the only thing I'll do to the motor, despite the baking soda trick sounding tempting to reduce can-flex. If the fixed motor doesn't survive even after reducing the power it is used at, it will be binned. A long time ago I wrote I bought cheap stuff to try electric flight. Well, now I know I like it and it might be time to upgrade!

Hugo
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Old 02-28-2009, 05:46 PM
  #72  
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HugoW
OK, NOW, its time to take a look at all the threads on the A123 battery packs!

I've got a number of them, these cells actually get hotter sitting in the sun on a hot day, than they do after a flight! My packs are 6S2P A123 batteries, pulling about 55 Amps full throttle.
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Old 02-28-2009, 06:31 PM
  #73  
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We've been flying MicroDan 2510-3D motors for over a year and Blake and I helped Dan figure out that an additional bearing(total of 3) was needed. Have never run into that problem yet on a MicroDan. Here's a vid of the Exhila being thrashed beyond belief with an MD on it. Don't know if your talking about Scorpions or not but the MicroDans are now Blakeproofed! Just got a Scorpion 2215-18T and haven't had any problems with it so far. Like the extra RPM's, quicker throttle response. I like the Hackers for their stout construction and no nonsense engineering with the front mount and back bearing support. Just wish they'd beef up the Hacker motor mount a little. I'll post some pics of my aluminum bracing I just got to bolster up the new mount I grabbed yesterday to fix the broken one. I'm working on it right now.
[media]http://www.youtube.com/watch?v=Bn36HaVOw24[/media]
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Originally Posted by kyleservicetech View Post
EDFRules
Good Point!!!
That's why I like the Hacker A40 and larger series motors (or any similar design motors) The far end of the magnet bell is supported by a large diameter ball bearing. The outside of this bearing is attached to the Inside Diameter of the magnet "bell" with several screws. The ID of this bearing is supported by the stationary stator part of the motor.

It is not possible for the Hacker magnet bells to "flex" and hit the magnets since the large diameter ball bearing absolutely prevents this from happening. The manual for these A40 and larger Hacker motors indicate they have FOUR ball bearings.

Sure, the Hacker and similar motors with this large diameter ball bearing cost more, but then they really work very well. I've got two Hacker A40 series motors, two Hacker A50 series, and one Hacker A30 series motor. The A30 series does not have the large diameter ball bearing. I run the A40 and A50 motors at 50-60 Amps full throttle with zero problems. This current drops to 20-30 Amperes average during flight. Of course I've got these motors VERY well ventilated with a direct blast of air from the front of the model. NO spinners are used, just a machined tapered prop nut made on my lathe.

I ran into the magnets hitting the stator with the GoBrushless motors, with the triple stack windings.
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Old 02-28-2009, 06:44 PM
  #74  
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You're opening up a painful wound for me! I tried them out on my 87" Extra with disaterous results. Almost burned the airframe to the ground when the capacitor blew out on my Spin 99. Can't take the sine wave generated by A123's. The "ripple effect" of A123's can be devastating to certain ESC's when using larger cell counts. But for smaller applications A123's have their place. Everyones using them for Rx packs now. You can use a 2s1p pack for unregulated servo power. I use them in my Extra and they're great for that just not as a main power pack. Not to mention they are just too heavy for good 3D work. Really dogged the airframe out . Great for sport flying but I wouldn't recommend them for 3D. Folks have kind of found the sweet spot-3DHS 55" Extra 300 SHP with a 6s1p A123 pack. Not too heavy for 3D but beyond that I haven't seen any successful vids/reports flying A123's on a 3D plane(good 3D not just hovering!) Here's my thread/saga on RCG about Giant Scale 3D planes powered by A123's:
http://www.rcgroups.com/forums/showthread.php?t=722914
and here's a thread on Advanced Power Systems for Giant Scale 3D planes:
http://www.rcgroups.com/forums/showthread.php?t=924189

Jason
Originally Posted by kyleservicetech View Post
HugoW
OK, NOW, its time to take a look at all the threads on the A123 battery packs!

I've got a number of them, these cells actually get hotter sitting in the sun on a hot day, than they do after a flight! My packs are 6S2P A123 batteries, pulling about 55 Amps full throttle.
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Old 02-28-2009, 07:21 PM
  #75  
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EDFRules
What brand ESC did you blow up with the A123 battery packs?

Yes, these A123 packs are heavier than the Lipos, but for my use, their much longer life span makes it worth while. I've run 220 Amp Hours through each of my 6S2P packs with zero loss of power to the motor. In fact, after about 70 flights on each model, the motors actually INCREASED in RPM from when the packs were brand new.

I'm running the Castle Creations 60 Amp units on two different 6S2P A123 pack/A50 Hacker motor setups, no problems noted. I'm pulling 55 Amps at full load on them. Don't understand the ripple effect, I've checked my systems with my Tektronis 2236 oscilloscope for this ripple, the ripple was far less than that found on my design brush type speed control I was using before brushless motors came out.

One of my design brush type ESC's was used with an Astroflight 90, with 38 Sanyo 2400 MHr cells. And, yes, I did blow a tantalum capacitor connected across the ESC input completely apart! Had acid all over everything!

The aluminum capacitors used on our brushless ESC's MUST be rated for high ripple currents, or they might FAIL! Never had a problem with CC controls.
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