Old Man Mike

I contacted Unitied Hobbies in Korea about the possibility of selling the Feigao 1308441S motor since they sell other Feigao motors. I thought that since they are close to China where the motors are made, they might be able to obtain them quickly. BP Hobbies has a link called "Notify Me When Available" at the bottom of the Motor link. Maybe if everyone clicked on that link (even if you are just a little bit interested), it will get their attention and make things go faster. I have only one spare motor myself and would have ordered more if I had known about the short supply.

I've also taken another look at alternative motors and so far have found nothing that compares to the efficiency of this motor in the 1 to 4 Amp range for the 2300 RPM/V speed:

[link=http://www.peakeff.com/MotorDetails.aspx?MotorID=2330&v=10.5]Feigao 1308441S Motor Data[/link]

(It is amazing to me that any motor can approach 90% efficiency for this size, cost and power. That is why they run so much cooler than the brushed motors even when carrying 3 times the weight.)

In order to use the existing 10 tooth pinion, the motor will need to have a 2mm shaft and be an inrunner type to mount in the existing motor mount. I suppose you could drill the pinion for a 2.3mm shaft if you found a good substitute with that shaft size.

Mike

13BRV3

I spent (wasted is an ugly word) quite a bit more time today looking at the signals on a non-Berg board. I'm quite certain now that the separate throttle signal is not available, but I did find some other interesting things.

The large aux connector on the bottom of the board has the combined RX signal with what appears to be seven channels. This is the same signal that I believe feeds the controller from the old style receiver. It also has the separate pulse for channel 5 (TI) and channel 6 (no function that I know of).

A question for Mike- In the standard DF setup, the hexfets do all the work of changing motor power. In your setup, you also have a throttle input to the ESCs. What would happen if someone with an old board used channel 6 to simulate a throttle signal? They could enable the ESCs via channel 6, then set it to max position. The normal DF throttle would still have full control of the motors via the hexfets wouldn't it? Do you think this would work?

Thanks,
Rusty

VRNowhere

Thank you for the information.

Sky High

Channel six is a regulated 5v output available in that multi-pin connector under the flight board. It can operate servos or just power an accessory. I use it to power my nav lights.

Old Man Mike

Rusty,

It is interesting to hear your thought process since I went down that same road. During the initial development when I used a separate receiver for the throttle pulse, I initially tried using channel 6 which is controlled via the knob on the side of the Futaba transmitter. I did not stay with that approach very long since it was most clumbersome to deal with an extra speed control, especially at low throttle levels. If you keep the duty cycle high to the motor when the main trottle is down, the current will shift from the hexfet over to the small resistor used to keep the voltage from falling below the 4.5 volt level. That will cause a shutdown of the motor and then you have to do a restart. After playing around with it, I finally shifted to using the single throttle control for both and was quite surprised that it worked so well.

Mike

msarid

Hi
What do you think about this motor, KV is little high but I think DF can handle it.

Moti
http://www2.towerhobbies.com/cgi-bin...?&I=LXLWW4&P=M
This is the motor spec.

Motor Diameter: 0.787" (20mm)
Motor Length: 1.18" (30mm)
Shaft Diameter: 0.079" (2mm)
Shaft Length: 0.413" (10.5mm)
kV Rating: 2650 rpm/V
Weight: 1.6oz (45g)
Input Voltage: 7.4-11.1V
Max. Constant Current: 5.5A
Max. Surge Current: 10A
Max. Constant Watts: 61W
No Load Current: 0.4A

Blackdragan

Good news! I just spoke with Dave Peru from BP Hobbies and they have the Feigao 1308441S brushless motor in stock. There was an error in the their previously inventory listing which has now been corrected. They have 30 motors in stock. http://www.bphobbies.com/view.asp?id=V219349

John

13BRV3

Hi Mike,

Yes, interesting indeed. It's also a real convenient having you test all this before I even think of it

Since the motors are back in stock, I ordered mine, as well as everything else. The only out-of-stock item is the adapter mount plate from DFI. I'd bet those can be found other places, though I haven't looked yet. Worst case, I can make my own, but if anyone finds another source, please let me know.

The only unknown for me is how I'll handle the throttle signal for the ESC's. I found some comments online about using a CD4017 decade counter to decode the pulses, so I may give that a try, though I haven't figured out the details to make it behave correctly. I hate having to add another receiver, but at least it's an easy option. It would be even easier if I hadn't dumped all my 72 MHz stuff on Ebay when 2.4 GHz came out [:@]

Cheers,
Rusty (let the waiting begin...)

Blackdragan

Rusty,

I think you can purchase the motor adapter mount plate here: www.helihobby.com/html/helicopter_brushless.html
You need to scroll towards the bottom of the page to locate it. Please let me know if this is the same one DFI uses.

Thanks,

John

13BRV3

Thanks for the link John. I'd be surprised if it wasn't he same as the one DFI sells, but unfortunately they only have one in stock. Theoretically, I should be hearing from DFI to see how I want them to handle the backorder, and I'm hoping they can give an ETA then. If it's too long, I'll probably drop the item, then either find or make it.

Rusty

LATER NOTE- I just ordered 4 adapter rings from- http://www.maxxprod.com/mpi/mpi-29b.html I have no idea yet if they're in stock, but we'll make it a race between them and DFI I guess

Blackdragan

Rusty,

Thanks for finding this new source. I just spoke with MPI and they have the motor adapters in stock.

Thanks,

John

13BRV3

Hi John,

Thanks for checking on that. Even in the order confirmation, there was no indication of whether they were in stock or not.

Rusty

msarid

Hi all
I need help from you. BP Hobbies do not make international orders so maybe one of you can order it for me. I will paypal the money before making the order.

Have a nice day
Moti

Old Man Mike

Hey guys, excellent work on the motor and adaptor sources! This is just what I had hoped for. Many people working on a project and sharing the info can do a lot better than just one guy.

So here is another challenge:

After see a maximum 2.5 lbs of lift from the converted DF, I wanted to understand why it is not closer to the theoretical 4 lbs. I believe the primary reason is that the DF gear ratio of 5.5 is not optimum for the motor. It we can get the ratio closer to 6.6, then I bet the total lift would move closer to that 4 lbs number. It looks like changing the pinion from 10 tooth to 8 tooth would do the job. I've looked around and could not find an off the shelf part. Maybe someone here is more of an expert in gear design and could help. Here is the base info for the current pinion:

24 pitch
20 degree pressure angle
hole for 2mm motor shaft

I looked at this source:

[link=http://www.stockdriveproducts.com]Stockdriveproducts[/link]

If someone could come up with a set of four that I could obtain, I would love to test it.

Mike

msarid

Hi
Because I can't get the feigao motors I found this two motors in Tower hobby .
please advise me witch motor is the best.

Moti

SPECS: Motor Diameter: 0.787" (20mm)
Motor Length: 1.18" (30mm)
Shaft Diameter: 0.079" (2mm)
Shaft Length: 0.413" (10.5mm)
kV Rating: 2650 rpm/V
Weight: 1.6oz (45g)
Input Voltage: 7.4-11.1V
Max. Constant Current: 5.5A
Max. Surge Current: 10A
Max. Constant Watts: 61W
No Load Current: 0.4A

SPECS: Motor Diameter: 0.787" (20mm)
Motor Length: 1.57" (40mm)
Shaft Diameter: 0.079" (2mm)
Shaft Length: 0.413" (10.5mm)
kV Rating: 2080 rpm/V
Weight: 2.3oz (65g)
Input Voltage: 11.1-14.8V
Max. Constant Current: 7A
Max. Surge Current: 15A
Max. Constant Watts: 104W
No Load Current: 0.5A

Old Man Mike

Moti,

What are the part numbers for those motors?

Also, I am still hoping that United Hobbies will start to offer the Feigao 1308441S since they said they are looking into it.

Mike

msarid

Mike
Towerhobbies P\N are:
1. Ammo 20-30-2650
2. Ammo 20-40-2080

Moti

Old Man Mike

Those are interesting possibilities. I could not find more detailed information on the winding resistance or efficiency vs current curves. The problem I see is that the first motor might be too fast for the 12 inch props with 5.5 gear ratio. The second motor might not draw enough current to allow good efficiency and power. It is hard to say without more data. I might order one of each for testing since both appear to have some potential. I would not recommend ordering four of either one since I do not know how well they would work.

Mike

Dirk Schooner

OK, I'm not an electronics engineer or a physicist, but I might as well stick my oar in here and say what I think based on how this is progressing;

The flight time of 3 mins with 21ozs and 1320 battery is interesting, also would be good to know how high it got and safely descended. A bigger battery should improve this, at the cost of adding more weight, and reducing the payload capacity even further.

The gearing may help if that is changed, but I think the basic laws of physics would say that "there is no such thing as a free lunch" (is that how Newton put it?).

While you are trying to use motors that best fit the frame (I know there are other reasons too), it may be that larger motors are needed, requiring more power and the circle continues......

As an aside, it was interesting to see how you had teathered the weight, this was an option suggested to me by a an engineer for a camera mount when I started a year ago, much like how real heli carry payload (chinook etc). I never tried it as I was worried about the 'pendulum effect' when flying, have you noticed this effect?

Anyway, i will shut up and let you experts carry on experimenting, it's all great fun to observe, a real voyage of discovery, good luck chaps!

Old Man Mike

Hi Dirk,

The 21 oz payload test was all indoors since I was interested in a maximum stress test without worrying about a crash.

No laws need to be broken to improve the payload performance. These motors have a demonstrated lift capacity of 1 lb each at a current of 3 amps with a 6.63 to 1 gear ratio and a 1260 prop. I am only getting 0.65 lb of lift per motor with the 5.5 to 1 gear ratio and the 12' DF prop so it appears the motor is operating outside of the optimum efficiency area. That is why I would like to try a 8T pinion which will bring the ratio closer to the optimum 6.63 to 1. I'm not sure if the pitch of the DF blades are close to a 1260 prop so that could also be a factor. I'm even experimenting by cutting off 1/2 inch of the prop tips to make a 11" prop just for testing (won't increase payload but will give me a different data point).

A higher mHa battery is certainly worth considering since the higher payload weight can certainly accomodate a heavier battery. I just want to optimize things with the current battery before moving on to bigger batteries.

Those elastic straps I used in the payload test are the same straps I use with the foam camera mount (see that Another Custom Mount thread). The springy pendulum effect is what makes the video and stills come out so well. It isolates DF vibration and movement from the camera.

Mike

Sky High

Mike, have you considered using more efficient rotors? How about doubling the length of the current rotor arms and frame stiffeners to create a larger airframe for more stability? A while back, I asked Jeremy at DFI about using longer rotor arms and he said that the extended length of the power wires couldn't handle the power drawn through them because of the extended length. Maybe it's a different situation with brushless motors though.

Old Man Mike

That might be an interesting expansion. Now that the brushless design is working, it does open up other possibilities like this. I have to smile at Jeremy's response - getting power out to the motors at these current levels is a non issue.

But first I want to make sure that we've got the maximum performance possible out of this brushless design. It really should be able to lift another pound of payload.

Mike

targit

Hi, I've been reading through this, congratulations on your mod It might be worth measuring the current and battery voltage under load, as you are getting pretty close to the 10C discharge rate.

Old Man Mike

Thanks Targit,

Yes, during the 21 ounce payload torture test I was running the 1320 mAh battery at close to 13 amps which is right at the 10C discharge rate. Of course that is three times my normal FX07 camera and foam mount weight of 7 ounces.

Since I have still not located an 8 tooth pinion sustitute for the 10 tooth pinion which would allow the motor to operate even more efficiently, I tried shortening the rotor blades from 12" to 11". I cut off 1/2 inch off of each side of some old folding blades. These were old blades that were quite badly chewed up from my early learning days. Even so, the reduced size allowed the motors to operate with better efficiency. The flying time was increased aproximately 15%.

Today I did some outdoors flying tests with my normal 7 ounce camera & mount. Those of you that have flown the original DF with payloads in the 7 oz range know how difficult it is to manage a good decent. You have to be careful to come down at an angle because it takes too much power to compensate for the loss of lift when decending straight down. With the extra power of the brushless version, this was no problem at all. It was almost like flying with no payload at all. In addition, the DF was easier to hold in a fix position and even less responsive to wind gusts. It was really a pleasure to fly.

Here are the flight times achieved with the 7 ounce payload:

Original DF Brush: 5.5 mins

Brushless with 12" blades: 6.5 mins

Brushless with 11" blades: 7.5 mins

I have run the 11" brushless version twice with different batteries to make sure of the results.

I'm probably going to order a 2100 mAh battery since the additional 1.7 oz weight will no longer be a factor. That should provide more than 12 mins of flying time with my camera system.

(still hoping someone will find a source for an 8 tooth pinion)

Mike

aerohelipilot

Mike
Will any of these toward bottom of page work? they are 2mm bore 8T on long and the other is shorterer with a lip.

http://www.helihobby.com/html/blade_...ARTIP6152-8-20