13BRV3

To my knowledge, the problem has not been resolve, and Spectrolutions is still working on it. "So far", mine is gone, but it's really too soon to tell, and a sample of one unit isn't meaningful anyway.

Rusty


PS- Stand by Mike. I'll answer your questions tomorrow.

flyingdutchie

What about the EPP1045 props that most of the quadcopters are using at this moment?

Old Man Mike

Hi Dutchie,

Now that the DF brushless modification is working so well with the large props and step down gearing, it may be time to see how well direct drive motors/props will work with 10' props. I took a look at the motors and ESCs used with the X-3D quads and was amazed as how much a set of four costs. $540 seems quite high. Compare that to $160 for the motors and ESCs used in this modification. The special ESC and matching motors should not be required for this brushless DF mod so we may be able to find a much more reasonable set of direct drive motors to test.

By the way, I was curious how much it would cost to build a brushless DF from scratch buying just the PWB controller and basic frame from Draganflyer. It looks like the total cost would be around $800 or maybe $850 after postage from the different suppliers. Add to that the battery, charger and transmitter for a complete system. Not too bad.

Mike

13BRV3

Hi Mike,

The test using A123 cells used an old Astro Model 101 "Super Whatt Meter". The full throttle test with the LiPo battery used an Extech 380947 clamp meter. The Extech is a pretty nice meter, and has the ability to save high and low readings, but I presume it normally gives an average reading. Given the nature of the power draw, I suppose it's possible that it's "average" is reading higher than it should. I guess it all depends on how it was programmed to behave, and only Extech knows that. I can see an interesting experiment here, but I'll try to resist.


Nope, I wouldn't expect the fuse to hold for more than a couple seconds. You're almost certainly correct that my meter is giving a misleading reading.


A123 cells are lower voltage than LiPos, so this is completely normal when comparing packs with the same number of cells.


No, I haven't tried timing flights. My hope was to find a more consistent way to measure it, since there are too many potential variables with actual flight. There are also significant differences in battery capacities, perhaps even from one charge to the next on the same battery. I would agree that you could run the test enough times to be confident in the results, but I didn't want to spend that much time on it.

Vacation's over. Back to work [&o]

Rusty

Blackdragan

Mike,

Is there a source to purchase the ("Y" cables or the 4 to 1 cable) which would allow the receiver output from the DF to connect in parallel to each of the four optical isolators http://www.medusaproducts.com/Opto/opto001.htm or would a person have to custom make them?

Thanks,

John

Old Man Mike

John,

You can buy three of these at $3.10 each:

[link=http://www.bphobbies.com/view.asp?id=V834691&pid=T090448]2 Female to 1 Male Y Cable[/link]

and one of these at $1.60 to solder to the DF receiver connector (this should have been on the conversion parts list):

[link=http://www.bphobbies.com/view.asp?id=V834691&pid=T641875]Male Connector for DF Receiver[/link]

(You might want to edit your link to the optical isolators - you've got an extra comma at the end resulting in a dead link)

Mike

Blackdragan

Mike,

Thanks for responding. Here are Jeff's comments from Medusa Research, Inc. regarding the use and wiring of their ESC Opto Isolators http://www.medusaproducts.com/Opto/opto001.htm for the Draganflyer:

Yes our Opto’s should work fine. Use the end with the wire to connect to the throttle. That would mean that all the wires from the Opto’s will be connected together. Yes, we sell Y connectors but an easier approach might be to use a 2x6 (0.1� center) header. The plugs will plug right into the header and all you would have to do is wire up the other side (wire wrap would work good) to common the signals.

Thanks,

John

tend2it

Hi Mike,
The prototype GPS support is discussed here in English with a video at the bottom ... [link]http://forum.xufo.net/bb/viewtopic.php?p=77430&highlight=gps#77430[/link] ... sounds like they did use a compass module with the GPS.

The prototype ACC module is also a cool addition for added stability ... [link]http://forum.xufo.net/bb/babelframe.php?trurl=http://forum.xufo.net%2Fbb%2Fviewtopic.php%3Ft%3D3737[/link]

They also did a autonomous motiontracker experiment here ... too bad the video link is down ... it basically takes off from the center of a square, levels off at a fixed height, moves over to the large square path, and flys nose in around the square w/o anyone at the controls ... really cool ... I asked Jast if he could fix the link. Info on their project here ... [link]https://ras.papercept.net/conferences/scripts/abstract.pl?ConfID=4&Number=1600[/link]

The X-BL X-BLDC controller pak is a little more expensive because it is a custom designed super fast I2C bus interface connection to the X-Base at 1 kHz update rate and the brushless outrunner motors are also custom wound Hacker motors.

Btw, with your mod, did you notice if the BL motors are sucking more power and battery time? Keep up the great work!

--Eric--

msarid

Hi mike
You checked the GWS notor? or you still fly with the Feigao. I did not order yet any motor so what is your recomedation.
What is opinion of the attached motor http://www.unitedhobbies.com/UNITEDH...idProduct=5230
Moti

Old Man Mike

Moti,

I have not yet received the GWS motor but it was shipped last week. I expect it any day.

The motor you are asking about has the right KV but the max current is too high and resistance is too low. For efficient performance the motor should have a maximum current rating below 10 amps. The resistance should be around 0.37 ohms and the KV between 2200 and 2500. You also want a 2mm shaft and 20mm body. I am fairly certain the Feigo 130s 40T (1308440S) would also work well but I have not tested it and it is probably just as hard for you to find as the one in the parts list.

Mike

Old Man Mike

Eric,

Thanks for that amazing GPS hold video link. That is exactly what I want to be able to do with the DF. The only clue I got out of the links provided was that they were using a 3 axis compass module. I would like to know what compass module they use and how they deal with the magnetic interferrence from the motors.

I attempted to select the BL motors so that there would be a high efficiency with an 8 ounce payload. I am getting better efficiency and longer battery life than with the original DF with that payload. Consider these numbers:

1) For a single 12 x 6 prop, it takes 39 watts to lift 16 ounces. The prop will be rotating just over 3700 rpm.
2) I have flown the 20 oz DF with a 21 ounce payload (total 41 oz flying weight) for 7 mins with a 2100 mAh 11v battery and just under 15 amps current. Assuming the voltage drop was down to 10 volts near the end of flight, the power used to hold that weight in the air was less than 150 watts.
3) A 100% efficient system would require: 41/16 x 39 watts = 100 watts.
4) So this converted DF is running around 67% total efficiency when carrying the maximum payload.

I would be interested in hearing about the efficiency of other quad systems.

Mike

13BRV3

Hi Mike,

I'm officially changing my answer

Yes, in fact I do believe the 15A fuse could hold at 17.3A. I've now tried 3 meters (Astro Whatt Meter, Extech clamp meter, and Eagle Tree data logger), and they all agree that I'm running well over 15A at full throttle.

I was almost ready to believe that the pulsed nature of the current could fool the meter, but just had to try to prove it. I used a freshly charge A123 batteries, and the Eagle tree data logger, then ran the DF at a mid to upper throttle level for about 5 minutes. The data logger said I used 1078 mah in the run. Next, I put the battery and data logger on my power supply to charge it, and got 1189 mah during the charge. Since charging isn't 100% efficient, this seems completely reasonable to me. From this, I conclude that the ammeters are reading correctly.

But how could the fuse stay together? I took my original 10A fuse, and used it with the Eagle Tree logger, and Astro Whatt Meter in series with the battery. I increased the current in steps of about an amp at a time, and the fuse blew at 14.6A. At this point, I was more confused than ever.

The only explanation I could come up with was that the fuses allow a significant overload before blowing. Sure enough, this is true. The following pages give fairly similar data regarding the amount of overload allowed.

http://www.russellind.com/Seneca/fuse.htm
http://www.littelfuse.com/data/en/Data_Sheets/297.pdf

The most conservative specs say that a fuse is allowed to sustain 110% (16.5A) of it's rated value for a minimum of 100 hours, and a maximum of forever. It's allowed to maintain 135% (20.25A) for a minimum of .75 seconds to a maximum of 10 minutes. 200% (30A) must hold between .15 and 5.0 seconds.

From these specs, a 15A fuse could hold 20A for an entire flight, but it's really living on borrowed time above 16.5A. I'll be swapping mine out for a 20A fuse for now, but if I build another one, I'll think hard about running the power directly from the battery, through a fuse to each ESC, as Mike mentioned in the improvement notes.

Cheers,
Rusty (feeling better now)

PS- I also learned that the lower voltage of the A123 pack invokes the auto power-down feature of the DF long before the capacity is used up, so I won't be able to use them. Time to order more LiPo grenades [X(]

PPS- Thanks to Mike for proofreading my post.

Old Man Mike

Rusty,

Excellent work. (you might want to change the couple of "V" to "A" for amps where you are discussing the fuse specs.) It is good to know that those fuses can hold a lot more current than the rated value.

Looking back at your post where you were getting 17.3 A and 160 Watts, I'm surprised we didn't catch the real problem of too low of a voltage from your A123. That current and power equates to 9.25 volts! No wonder you had a different result.

Funny that I had convinced myself that the problem was with the measuring tool, especially when I looked up the Watts-Up watt meter and found that it measures the peak current during the first 3 seconds. I now see that your watt meter appears to be a true averaging meter. I also knew that I was running closer to 15 amps, especially after flying 41 ounces for 7 mins with the 2100 mAh battery. (15 amp discharge rate for 7 mins would be around 87% of the 2100 mAh which is what you would expect for that rate).

This whole discussion proves how easy it is to get fooled without someone else checking the data. That is the great thing about these forums.

By the way, I've ordered a digital scale that will handle up to 11 lbs which should allow me to do the same thrust measurements as you are doing. Since you've used several different watt meters and loggers, can you give some pros and cons of each? I would especially like a data logger that stores current, voltage and power to memory which could be retrieved via USB after the flight.

Mike

13BRV3

Hi Mike,

Thanks for the proofreading service. I think I corrected all the offending letters, but let me know if I still have something screwed up.

From now on, I'll stick to LiPos for any testing, so as not to confuse the issues. Also, they just aren't suited for smaller models anyway. I'll have to recheck it, but I'm pretty sure I saw a peak of about 20A with the fresh LiPo, though it fell to the 18A range in just 20 seconds or so. The only way I have to measure it is the clamp meter at the moment, because of the difference in the plugs. I need to just break down and change those silly DF plugs out for Deans and be done with it, then all the toys will work and play well together.

Glad to see you're getting some new scales. With the way you're testing motors, are you sure 11 lbs will be enough I admit that I have mixed hopes for your new motor test. On one hand, it would be nice if it's better than the Feigaos, but if it's much better, I'd feel compelled to order a set

As for meters and dataloggers, I REALLY love my Eagle Tree Micro Logger! http://www.eagletreesystems.com/MicroPower/micro.htm I bought it quite a while back, and I've got all the extra modules they came out with later. So far, I haven't tried the extra modules, but I'll get around to it. I was hoping to post a graph of the LiPo at full throttle, but I just don't have all the connectors I need to put it all together right now. There are probably other dataloggers available now, but I haven't looked at any of them, so it might pay to do some research before you buy. I don't think you could be unhappy with the Eagle Tree though.

Cheers,
Rusty (tinkers more than he flies)

PS- CF rod on order to make a larger DF [X(]

Old Man Mike

Wow! Thanks for that Eagle Tree link. I'm going to order that Seagull Pro Wireless Dashboard System with the GPS module. You get real time GPS plotted on Google Earth maps, audio tones for rate of decent and ascent, current, voltage, RPM and temperatures! This should allow much higher flying with that real time audio. Plus if it gets out of range and comes down out of sight, the last GPS position will tell you were to find it.

Mike

13BRV3

Hi Mike,

I've been seriously tempted by the Seagull Pro, but so far have resisted the urge to buy one. Do me a favor, and don't tell me how much you like it

Rusty

Old Man Mike

I was finally able to test the GWS motor. Although it flew about the same as the Fiego motor, there were several things I did not like. First the motor shaft is too short so the pinion is only about half on the shaft. The motor has a little more power but draws a little more current and weights more. It does not have a collar to center in the adaptor plate and the body is longer in length. Also the motor does not have a smooth rotation when turning the shaft by finger and it does not start running as smooth as the Fiego.

Bottom line, I have spent about $100 testing alternate motors and have yet to find one that beats the Fiego motor. I will talk to the owner at RC World of Planes Monday to see if he can also stock the Fiego motor for foreign shipment.

Mike

msarid

Mike
Thank you for your effort.I send an email to BP ask him to ship motors to my friend APO address.so until now i still looking for the motors.[&o]
Have a nice weekend
Moti

kokomiko

Hi

Thanks Mike ...you are genius ..and thanks to all the others contributing to this project.
While I am waiting to receive all the parts I made a bigger frame for the DF - 64cm axis to axis = 30cm arm lenght.
Today I tested the new frame with Ti enabled and HD motors.
It works great without any problems at all and is very stable. So no issues here with power/cable lenght or else to make it bigger. And you can see it much better when you are flying high of course.
I belive with the brushless upgrade it will be a great and stable flyer for AP.
And it realy looks BIG.....

Some video from the first test flight
http://video.google.com/videoplay?do...13515726284587

13BRV3

Sounds like great minds think alike, but yours seems to work faster

Mine has 333mm arms, only because it divides evenly into the 1 meter CF rods I bought. I'll finish up the motor wiring today, and give it a go, but it's good to hear that it will work fine. I haven't decided if I'll order a second set of BL parts, or just move the existing BL setup over to the BIG DF.

Cheers,
Rusty

Sky High

Finally, a supersized DF! I've been wanting to see something like that for a while and am glad to see that it works. That larger frame is definitely easier to see at a further distance. Why didn't y'all just double length of the rotor arms and stiffeners to an even 24" each? Would the rotors now being further apart make a difference in the turbulence that they produced being closer together thereby reducing frame vibrations?

Kokomiko, what was that object hanging way up in the sky at the end of that contrail? It also appeared that the contrail did a 90 degree turn.

13BRV3

Hi Sky,

I was worried about the stiffness of the frame. The stock DF is about 18.5 inches between rotor centers. The larger one I made is 30 inches, which is really a pretty big change. The BL mod adds so much power that the stock DF frame flexes quite a bit under full throttle, so there's definitely a limit to how far you can extend the frame without doing something to stiffen it. For the superfly, I used solid CF rod rather than hollow CF tubing. I'm sure that helps some, but probably not all that much. BTW, the larger model is 2.5 oz heavier than a stock DF.

For the BL version of the superfly, I think I'm going to try to use direct drive outrunners. Since Mike seems to love researching this stuff, I'm hoping he's already got some picked out for me

BTW, I just flew it outside, and it seems to behave just fine. The wind is gusting to 15 mph or so, and really swirls over the obstacles in the yard, so it wasn't the best conditions to test it.

Update- I got to fly the superfly later when it was calm, and it flies just about the same as the standard size DF. It might be a bit more stable, and a bit less maneuverable, but it might also be my imagination. It's a bit underpowered too, but I can fix that :-)

Cheers,
Rusty

Sky High

I would definitely think it would be more stable because the rotors are further apart but why would it be less maneuverable?

So we now have 3 sizes to choose from. The Micro below, the standard and now the Superfly!

kokomiko

High Sky

The reason for the size is, as Rusty wrote, the stiffness of the frame and to be prepared for the extra load of the BL upgrade.
Secondly, I belive, it effects the maneuverability because of the longer ways to rotate the centerpoint at the same degree.
Rotation of 45 degrees makes the way app. 30% longer = slower reaction

The object hanging around there is the fixing point for a hoop takraw net... thats a game they play around here...its actually a rope between to bamboo sticks (you can see the left one in the video) and in the middle of that rope is a guide roller to lower the basket to get the ball out when they shoot a goal. (That will be the white point you can see)
More info about the game here [link]http://www.thai-blogs.com/index.php?blog=5&p=1369&more=1&c=1&tb=1&pb=1[/link]

Old Man Mike

Kokomiko,

Thanks! And congrats on the large frame construction. I noticed that the carbon fiber rods have a ring terminal at the end. It almost looks like there is some solder involved. Can you give us more detail about how the carbon fiber rod is attached to the ring terminal? It looks like a very good idea.

Mike