|Feb 14, 2012, 08:49 AM|
My first quad - x525 /w DJI Naza (amazing indoor performance)
THIS POST HAS BEEN UPDATED WITH ALL MODIFICATIONS AND FIDDLING SO FAR!!
my setup is this:
FC: HobbyKing Board v2.1 (upgraded to DJI Naza FC)
Motors: Turnigy D2830/11 1000 or 1100kv (not sure because on the motor it says 1100kv, in the specs sheet it says 1000kv)
ESCs: HobbyKing BlueSeries 30Amps
Battery: Turnigy 3s 4000mah 30C Li-Po
Tx/Rx: HobbyKing 6ch 2.4Ghz (upgraded to Graupner MX-12)
I finished my frame today, did some tidying up and am now sharing some pics with you. I am really happy with how it turned out, although the frame did not impress with quality. Everything flashed and configured well, however, I was getting the lazy motor with the 4.7X flash so I flashed it to 2.5. I believe it might be fine now, but not really sure since I've just done some 5cm hops in the house. Snow is 50cm thick outside so wont be trying it outside anytime soon. The reactions appear a bit too sensitive but there is no way to adjust sensitivity on this radio (if anyone knows a way to do it from the board, I am all years).
I decided to leave the landing gear off for now since it is missing half the bolts. That also saves around 100g in weight. I did balance the props and will have to balance the motors as well. Right now the props are 8x4 because those are the ones that came with the HK order. I am waiting for some 10x4.5 eBay ones.
AUW is 1088g, and weight without the battery is 735g. I've tried to keep things organized and tidy and I think I did good.
Also, the black boom is intended for a + configuration so I've placed it on motor 4 (back right).
Here it is:
I am particularly proud of my harness.
Quad is now 1172g AUW (with a 3s 4000mah battery). Installed the landing gear, not as it was intended but still should do the job.
I bench tested the spare motor today. Also my 10x4.5 props arrived so did a test with them as well. Results were very interesting to say the least.
With a 2s LRP 4600mah battery the 8x4 prop gave around 270g of thrust at full throttle, 8 volts, 3.9 amps.
With the same battery the 10x4.5 prop gave just over 550g of thrust at full throttle, 8 volts, 9.4 amps.
I have only balanced the props for now. I will balance motors tomorrow. Also I am getting the feeling I will have to get some better prop adapters. I expect that the amps rating will go down a notch when I balance the motors, there is quite a lot of vibration at full throttle.
Last minute update. Just hooked up a 3s to the test bench. Got 500g of thrust (6.7 amps) at full throttle with the 8x4 prop and got 900g of thrust (15.3 amps) with the 10x4.5 prop at full throttle. This motors seems to have good potential.
After spending hours balancing props and prop adapters and using absurd amounts of tape to do so I finally had my first attempt at a maiden flight, lasted about 5 secs, then broke a prop, but thankfully that is all that broke. I was in the office and am kinda angry I didn't take more props with me but I only balanced 4. I tried to trim it on the ground a little but the trims seem to have delayed effect and the controls are waaaaaay too sensitive. However, the lazy motor problem appears to be absent with the 2.5 software. I will have to either find a bigger place or do some hops before I try to liftoff or pray that the snow will melt soon so I can go outside. Anyways, I will balance more props tonight and will be back in the office tomorrow (Saturday) for more testing.
I have to say that I am pretty happy with the motors, after oiling they didn't require a lot of balancing, they were pretty good. For balancing I zip tied my android phone really tight to the boom of the motor I was balancing and used an app called Seismo (not sure if it is available for iphone). It gives a very good indication of the amount of vibrations.
I am also thinking of maybe cutting down the motors shafts a little with the dremel. They are a bit long and I believe that cutting them down will improve the balance of the whole prop + prop adapter vibration problem.
Yesterday I ordered a Graupner MX-12 radio system /w telemetry and it is on its way. I believe it will help a lot in the control of the quad, and I can use the existing radio system on something else that doesn't require exp and dual-rate.
I also ordered a little something extra that will, I hope, greatly aid my quad in flight stability and takeoff and etc., but I will not yet share what it is.
And speaking of props, in the next three pictures you will be able to see exactly how unbalanced are the props and prop adapters and what I am forced to deal with. As you can imagine balancing one prop takes at least 20 mins. I actually wonder how the stacks of tape did not fly off during my testing yesterday.
Now when the prop horror is over I would like to turn your attention to the FC vibration isolation that I have devised.
So basically I cut the sides of the lid of the foam box that the HK FC came in and divided them into 16 square (more or less) pieces, 4 for each mounting hole. I mounted the plastic spacer bolts to the center plate and put 2 pieces of foam, one on top and the other below under the nut. Then I mounted the FC to the plastic spacers using some of the small bolts that came with the frame kit and put 2 pieces of foam, one on each side of the board. I didn't tighten the bolts or nuts a lot in order to keep it a little loose but not too loose to wave around. I think the results are good for now, will be able to say if it really works when I get the chance to make it hover.
SUCCESS!!! My first (sort of) hover and indoor flight was successful in terms of no broken props and no crashes. This this first video are my mostly successful take-offs and short hovers. I am glad I managed to trim the rudder well, but I will need to go outside to trim the rest. In the office you have to correct it all the time. It is interesting how the sound of the props and motors changes when it goes up to about 1.5 meters. I am really happy with the results. In this first video I am flying with a 3s battery but actually those were the last flights before my last battery was depleted. The first videos are further below. At the end of the video you can hear a "boom" type of sound, that was one of the tape balance stacks from one of the props flying off and hitting the boxes. I was wondering how that didn't happen sooner. Keep in mind that during this testing 3 A/C units were operational and blowing at the ceiling.
In this second video are actually my first videos roughly following my learning curve, from dragging around on the floor to taking off. Up until the 7:35 mark I am flying with a 2s LRP battery. I am really happy how it handled with that battery and I am also happy that I proved eCalc wrong. It said that it would not fly, needing 93% to lift off, in reality if was lifting off at around 75% and it was a bit easier to control than with the 3s battery later.
So, overall I am really happy with today's testing. I've determined that the board has a good potential to be stable. First chance I get I will find a large open field and will test fly it.
So, about those prop adapters. I did make a considerable leap in vibration reduction today from only a few simple steps.
First, using my dremel, I cut down the motor shafts. They were about 15mm high and I cut them down to around 8.5mm. I think the vibrations lessened a little and the sound the motor makes also changed.
Next, again using my dremel, I cut down the prop adapter. Did not measure it, but I cut it down about 3mm so that when I tighten the nut it will stay flush at its top.
Then I actually replaced the prop adapter head with a common 5mm nut from the hardware store. All other components stayed the same.
At the end of the operation the results were these: before the top of the adapter head was at 41mm, now it sits at 26.5mm, so about 15mm lower. As a result I can almost certainly say that the new version of the adapter will NOT need any balancing. At very high throttle the prop and balancer are very smooth and there is very little vibration. Haven't tested it in flight yet but will probably do so next week.
Another day, another successful flight. BUT before we get there I would like to show you my battery strap, brand new. It grips really tight, quite happy with it, i only need to glue a piece of velcro to the battery as well so that it would grip it as well and not only squeeze. (I am sorry if the pics are not of their usual quality, but I only had my phone with me at the office today)
Now I would like to show you my camera and camera anti-vibration mount. Don't laugh too hard, this was made for a 4ch toy heli which had a lot of vibration, in any case it does the job on the quad as I hope you might be able to see in a vid below on the on-board video.
And now the videos, first one is of the quad. This time I remembered to turn off the A/C units and I have to say that made a big difference, although the quad was still moving around from the turbulence it created. I can honestly say that cutting down motor shafts and prop adapter shaft did reduce vibration considerably. I did, however, discover today that motor 3 has a bad bearing which was causing some minor vibrations but not overheating, so I will have to replace it. Overall, motors did not heat up much, at the end all were around 38 Celsius.
In this second video, you can see the on board footage. As you might have guessed from seeing the camera above, the quality is not so great, and the FOV is really narrow, and the recording gets stuck every 5 secs, BUT in the brief moments when the quad is not hitting the group camera first you could see that there isn't a lot of vibration. At least I hope you could.
Further improvements in vibration reduction!!!!
When I ordered my motors from HK I had read in the reviews that the prop adapters that come with the motors are really bad (which later turned out to be true), so I ordered some prop adapters off eBay. On the pics they looked pretty much the same and I though that they will be also bad. WRONG!!
The extra adapters arrived yesterday, and I noticed that they were different that the ones that came with the motors. The adapter shaft was shorter, and they didn't have a washer. When I put them side by side with the old adapter shafts it was obvious that the new ones were better (see picture below). The thing that the prop rests on with the jagged surface (don't know what it is called) was sitting so much tighter on the bottom of the prop shaft than on the old prop adapters. Also the new ones were exactly as tall as the shortened old ones.
So naturally, while replacing the motor with the bad bearing I replaced the prop adapter as well. The results you can see in the pics below, I will let my phone do the talking.
(Don't mind the ESKY Transmitter, this is a simple 4ch radio that I use to do testing so I wouldn't have to disconnect everything from the FC and other Rx every time I decide to test something.)
This is just the motor at 50% throttle:
This is just the motor at 100% throttle:
This is the motor with the OLD prop adapter:
This is the motor with the NEW prop adapter:
This is the motor with the NEW prop adapter and propeller mounted:
So after that I replaced all prop adapters with the new ones, just kept the washers and the nuts from the old ones. The test was done with the 3s battery I normally use for flying.
Soooo, back to vibration reduction. I noticed some people are using heat shrink to fit their props, so I decided to give it a go. My props have 6mm holes in them so I would put 2 layers of heat shrink in order to get a tight fit. They shouldn't go over the height of the hub, otherwise it is impossible to tighten the nut. That way, the prop is actually pretty centered on the prop adapter so now I could do without the washer. I did try the zip tie think that n3m1s1s recommended but I am not sure it will work for me, at least at this point.
And now let me turn your attention to my recent upgrade. I got my brand new DJI Naza and my Graupner MX-12 radio system. Today I had a chance to test it, finally. I did have a funny problem with the Naza, but it turned out that I had it mounted backwards, so every time I tilt it, it would rev in that direction and it would flip, well only did that once, and them I knew it was backwards. It took me about 3 hours to go through the Graupner's manual and get it set up properly. It is an amazing radio system, and the telemetry works great. I will probably get the 12 channel version later in my quad endeavors.
I soldered the VU's power wires to the outside of the bullet connectors of the power harness, still looks pretty clean.
I then mounted the VU unit on the opposite boom to my li-po alarm.
I cut out a 5x5cm piece of plastic in order to mount the Naza on the existing bolts from the HK board. As I didn't want to glue it to the plastic, I drilled two additional holes for a zip tie. For now it is holding pretty tight. Also removed the red wire from the last ESC, plugged everything and placed the receiver in the only position that did not stretch the wires too much.
And here is the video of the first flight. I used 50% dual rate on ele, ail, and rud. Settings are absolutely stock, I have not adjusted gains yet, and as you can see it is a bit twitchy. Any ideas in what direction I should adjust them would be welcome.
Today I did some dialing in. It took 1 hour and 2 broken props, but the results are very good. There is some strange rocking which can be seen in both videos, if anyone has an idea what could be causing it I will welcome their input.
So, did the endurance test today. It did 12:13 mins on a 3s 30C 4000mah Turnigy before the li-po alarm sounded. That was with the watt meter on-board so it might go a little longer without it.
At the end of the run the battery temp was 35 Celsius.
All motors were at 42 Celsius.
ESCs were at 30 Celsius.
In the pic below you can see the data from the watt meter.
Um - minimum voltage
Im - minimum current
Up - maximum voltage
Ip - Maximum current
It is interesting that according to this, each motor draws almost 6 amps to hover. According to eCalc each motor should draw a little over 4 amps and watt per motor should be 42W not 65W but flight time at hover is almost the same as what I got.
Any comments and suggestions on the results of the watt meter are most welcome.
So, today also I had a chance to test the quad in a large showroom. Settings are the same as in the last video, only the venue has changed. The difference in performance is amazing as you will see in the video. When I push the quad up and down it returns to position by itself. Almost perfect settings, will take some more tinkering with the software but this is pretty close to rock solid.
I have started a new thread HERE due to big frame mods.
|Feb 14, 2012, 11:50 AM|
|Feb 14, 2012, 12:02 PM|
I also have X525. The fiberglass mounts sucks, they do flex and will brake if you crash, so mount directly to the frame by using aluminium motor brakets.
Also your harnes is NO good (sorry bro), it may suddenly disconnect during the flight. better use XT60 connector and PS board.
|Feb 14, 2012, 12:26 PM|
the only thing I can see going wrong is using the same male connection on both positive and negative.
|Feb 14, 2012, 12:38 PM|
|Feb 14, 2012, 12:47 PM|
|Feb 14, 2012, 01:19 PM|
You quad looks good, I can see that you have fixed the landing gear so it doesn't move. I might have to try this given that half the mounting bolts for my landing gear are missing. Did you get your board flying yet?
|Feb 14, 2012, 06:31 PM|
o well, my friend just crashed his plane last weekend, because he is using bullet connector. so do you want to take chances? I don't think so. quad copters produce lot's of vibrations, especially with aluminium frames. some guys using hot glue to keep things in place.
|Feb 15, 2012, 02:13 AM|
|Feb 15, 2012, 04:42 AM|
|Feb 15, 2012, 06:35 AM|
Joined Nov 2008
Looks really good, very neat, nice job
I was just about to click the add to cart button (with this set up: http://www.goodluckbuy.com/x525-v3-q...lticopter.html ) until I saw this.
before I do, the is 1 or 2 things I would like to know.
how much thrust does it have with these motors?
I plan to have a 138gram HD camera onboard just for filming but I am worried how it will go with the power-weight ratio with the camera on it.
How stable is it with the HK board?
Also (there is a good chance you have found this out already but) if the reactions are to sensitive, use the gain controls to soften it out
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