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Old Nov 05, 2012, 02:53 AM
Micro Jet Pilot
Chris T's Avatar
Joined Jul 2005
2,091 Posts
Hi,

after Dan mentioned to me that his experience with the 10mAh battery wasn't that good, I had a closer look at the specs. While it was sold as a 20C cell, the supplier has changed his web page and now it says 8C continous I was expecting to pull 30C peak out of a 20C cell, but I was mistaken. Considering that the motor is pulling 200mA without getting hot, 300-400mA peak would be nice. The servos and the rx are going to pull some current too. I will start testing with the battery now to get a feeling. Luckily I can fit two of these batteries in the fuse. The 20mAh FR lipo won't really fit. Are there any other battery options? What about super caps? There used to be those lengthy 20mAh batteries. Was it kokam? I knew the power supply would be the biggest issue. Where is the latest generation 10mAh battery?

Chris


P.S.: Dave, what's up with that servo?
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Old Nov 05, 2012, 03:22 AM
Flying Dutchman!
robertboxhoorn's Avatar
Nederland, FL, Emmeloord
Joined Sep 2011
368 Posts
Hyperion got an 70mah stick pack maybe if you strip it down you can use it? Its 20-45burst
http://www.microflight.com/Online-Ca...ith-5mm-Bahoma one other Battery if you wanna use 2
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Old Nov 05, 2012, 04:24 AM
Micro Jet Pilot
Chris T's Avatar
Joined Jul 2005
2,091 Posts
Hey Robert, the 70mAh is way too big. A single of the 20mAh you mentioned should do fine. 400mA burst. On the plantraco site it is listed with 11mm width instead of 12 like on oter sites. Maybe I can use a hammer to make it fit

Chris
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Old Nov 05, 2012, 07:01 AM
Fear me, I'm a space-duck.
hanzie's Avatar
Nederland, GE, Wageningen
Joined Nov 2011
288 Posts
Nah, just cut a bit from the side of the pack. I don't see what could possibly go wrong!
I got some small batteries from some old silverlit (I believe) toy airplanes/helis. Not sure if those can deliver enough power for this one though. Also, you probably can't get them seperately...
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Old Nov 05, 2012, 01:02 PM
Registered User
chester2240's Avatar
United States, CO, Westminster
Joined Jul 2011
575 Posts
Maybe you can carry the fuse to the buttom of the jet like the F-16 does so you can fit the 20mah on its side or use 2 of the 10mah on top of each other.
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Old Nov 05, 2012, 02:20 PM
Flying Dutchman!
robertboxhoorn's Avatar
Nederland, FL, Emmeloord
Joined Sep 2011
368 Posts
Or let the the battery fit in the cockpit :-)
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Old Nov 05, 2012, 03:59 PM
Micro Jet Pilot
Chris T's Avatar
Joined Jul 2005
2,091 Posts
Just testing the new batch of controllers
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Old Nov 05, 2012, 10:33 PM
Registered User
Carbondale PA
Joined Aug 2005
552 Posts
Chris,

Your 3" squall is going to be amazing! I can't wait to see her fly.

I have a question on your new controller. I am thinking of shrinking my A-10 down to around 4.5 inches with two 10mm fans. Will your controller run two motors?

Joe.
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Old Nov 06, 2012, 12:45 AM
Micro Jet Pilot
Chris T's Avatar
Joined Jul 2005
2,091 Posts
Hey Joe,

that's a good question. I have been thinking of this too. I guess you will have to try. If it doesn't work, you will have to get a second controller They are small anyway. It might work well with a certain motor arrangement: While testing I figured that when motors are aligned close to each other, they try to turn each other. The one magnet aligns in the magnetic field of the other. If you turn one motor, the other one is rotating in opposite direction. You would have to use this effect to sync the motors I believe. You would also have to ask Dave kindly if he can flip his fan design for a left handed version. How cool would it be to have an A-10 that size with counter rotating fans

I did a lot of testing of the new standalone controller yesterday. I optimized again the code and the blocking while testing with the 10mm fan and the big 20mm setup from the big squall alternatingly. Remember that this controller initially was in the 6'' squall and is capable of pulling up to about 3 Amps dependent on cooling. I figured, that the big motor ( maybe in conjunction with the thin power leads I had attached) would cause dropouts during startup. I had left away the big 220uF cap for the 10mm setup, which was fine but lost the capability of driving the big motors reliably. So for the controllers I send to you guys, I intend to put the big cap on, so the controller does what it is supposed to do under all circumstances. I will finish 6 controllers on the weekend.

The guys who showed interest, please pm me your addresses.


Chris
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Old Nov 06, 2012, 01:09 AM
Registered User
Carbondale PA
Joined Aug 2005
552 Posts
Chris,

I would love to give it a try! Maybe on my new 1/72 scale A-10 first. I am actually using counter rotating fans on the model now.

Joe.
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Old Nov 06, 2012, 11:15 PM
Registered User
Carbondale PA
Joined Aug 2005
552 Posts
Hi Chris,

The 4.5 inch wingspan A-10 would be really cool with counter rotating fans. I am now thinking that I will have to work on the super micro A-10 next. However, I have a few more questions. DT has a Rx46-2 receiver that weighs only 0.16g. It can drive two motors for twin steering mix. http://www.deltang.co.uk/ Will the receiver work with your new controller? I would have to use two controllers for this set up.

My second thought was to try and use one controller, and make the model 3 channel like my 1/72 scale version. That would be really cool!

However, the twin steer A-10 would be very light weight. I would use the Full river 8mAh or 10mAh cell. I think It would be less than 2 grams RTF.

I was also wondering the weight of you new controller.

Joe.
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Old Nov 07, 2012, 02:35 AM
Micro Jet Pilot
Chris T's Avatar
Joined Jul 2005
2,091 Posts
Joe,

yes the controller is supposed to work with the DT rx. While I was always working with a ppm signal, which DT also seems to put out (very interesting), I modified the code for you guys to read a standard throttle signal (active high). I am testing with the AR6300 and they all should be compatible. Twin steering sounds like a cool idea. I am actually feeling much more comfortable with the thought of using two controllers, cause I am starting to doubt that you can run two motors reliably from one controller, especially at startup. Give it a try, it would be interesting, but rather assume you need two. You think one 8 or 10 mAh bat would be enough for two motors? In this case, you could probably use 2 of the shrinked controllers, which uses the A3903 as H-bridge. I have completed that one last week too, but at 200mAh+ motor current, I could see a difference in rpm compared to the current version. There are soo many options. Weight of the current version must be around 100mg. I will post pics on the weekend.

That rx you mentioned is very interesting. Supply current is good too. I am starting to wonder if I should keep on fooling around with the 915MHz stuff. The SI4320 will not longer be sold. I have 20 left over. The new chip is the SI4355, very interesting. Only 3x3mm. But there's a need for an LDO cause these chips don't handle the 4.2V. The next problem is that the uC needs to run on battery voltage to drive the bridge and read motor voltage, but also has to drive the rx chip to program it. I am thinking of using only the pull up resistor of the atmel to drive a 1, so the esd diode in the rx can limit the voltage during programming. There are really small LDOs though I think it's time for another digikey order.

Chris
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Old Nov 07, 2012, 12:30 PM
Registered User
ITALY
Joined Sep 2004
928 Posts
ism rx

Chris you can consider microchip MRF49XA transceiver for replace si4320,is pin to pin compatible,only some change in code.I have ordered some for replace it on my plantraco compatible rx.But the code change on my rx don't work again.
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Old Nov 07, 2012, 10:42 PM
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Carbondale PA
Joined Aug 2005
552 Posts
Hi Chris,

I think that the 10 mAh LiPo will work, but it may only last a few flights as we would be pushing it very hard. The 20 cell may also be an option, but I would like to keep the model as light as possible.

I did some rough calculations on the 4.5 inch wingspan A-10 using the DT twin steer receiver.

Airframe - .5g
LiPo with connector-.49g
Rec-.160g
Controllers-.2g
Motors .25x2=.5g
Fans?

1.85 Grams + the weight units.

2 grams as an all up RTF weight is possible. I am thinking that we need around 1-1.2 grams of static thrust out of the two 10mm fan units. Do you think that this is possible?

I built up a few motors to test when building my 1/72 scale A10. I made a 2 magnet 4.4 ohm motor using two of the 4x5mm magnets that ran well, but only produced 2 grams of thrust. I am sure this was because of the limitations of the A1442 chip that I was using. I ended up using the two 6mm motors as they had the best static thrust.

The 3 channel version using the standard DT receiver would also be around the same weight if one controller will run two motors! The 3 coils would only add around .9g to the models weight.

Not sure which is the best way to go. I think that the first step is to see what performance we can get from two 10mm fan units and the 10 LiPo cell.

I will start a build thread on the 4.5 inch wingspan A-10, so we can keep this discussion separate from your amazing 3 inch wingspan Nano Squall!

Joe.
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Old Nov 08, 2012, 01:04 AM
Team30 Micro EDF
NitroCharged's Avatar
Adelaide, Australia
Joined Apr 2004
11,245 Posts
Joe, did you ever post about your little A10, that you flew at JR, anywhere?
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