Thanks, Howard. Oh, there was plenty of complaining and issues, but mostly it’s my ADHD and clients who won’t stop booking me for photo gigs. Don’t they know I have a copter to tune? Sheesh...
Cool! I'm seeing 24.8 to 24.9 max voltage on my logs but I have bigger batteries which may make the difference.
Actually, I’m running it on 5S. The Alexmos board I’m using is only rated to 4S, but somehow it’s working. And the battery is barely breaking a sweat. After a full charge 3 days ago, I probably have nearly an hour of running it, and it’s still showing 87% on my LiPo meters. I’ve got the new 32-bit high-power (up to 6S) Alexmos board on order, but it isn’t shipping until next month.
I just checked my other recent GPX files, and they all list 24.9 or 25.0. But this one was different. Why? I just figured it out. This flight I immediately “floored it” on launch, rather than running up the motors a bit. So the voltage sagged a bit. Look at the Watts column of these two flights. Have I mentioned how I love having this kind of data to reference?
Steve, I like the red tail with lights, does that work well, how high of winds do you fly in with this ship?
Steve, what type of dampening are you using? Do you have any idea how to get my alexmos 3axis to face straight ahead? When it's booted up it want to stay to the right about 30 degrees, Thanks so much,
Jason, I plan on adding some more orientation lights. Right now I have a couple of bicycle LEDs on the side outriggers, too. But I haven’t flown very far away yet, and I’m still learning to deal with orientation while flying with the 3-axis. The FPV link is next up, so I can see what the heck I’m doing. And I just installed larger main booms, which is why I was waiting to figure out which arms I want lights on. I have 20 meters or so of different color LED strips to choose from. But I’m not going to bling it up too much.
I have too little dampening right now (2 blues and 4 reds), so I have to add more. As far as follow mode goes, make sure you calibrate your ACC and gyros, and adjust the deadband, etc. Mine’s a few degrees off, but that’s temporary...I don’t have the gimbal radio yet. I’ll be able to trim it with that.
Thanks so much, is there any videos that show how to do that type of calibration? Some one told me you can adjust something with the yaw offset? Don't know how to do that , that bird you have looks amazing. What a great job you did ,
Thanks! There’s a ton of videos out there. Alex even did one himself (with English subtitles) that explains follow mode.
Did my first flight with the 5D Mark III on the copter today (with the 17-40L lens). Had a bit of wind, but the copter still handled it OK. The video’s downloading right now, but just wanted to put some numbers up here. Video is below. Again, with the 6S system and two 8000 mAh Zippys, the copter’s about 22 lbs AUW, and flew for 7.5 minutes without breaking a sweat. Looks like the batteries were at 45% of capacity when I landed (just got tired of fighting the wind). Oh, and my other MKGPS works fine, so my problem yesterday with the GPS was clearly a busted part. Off to Riley she goes! As for the gimbal, it needs stiffer vibration isolators, which is very evident in this video. I expected that. The gimbal is very twitchy...I can see it when it's in the air. It needs to be a little stiffer up there for the motors to do their thing IMHO. MK Version: FC HW:2.5 SW:2.03d + NC HW:2.0 SW:2.03b Flight date: 2/19/2014 3:17:15 PM Flight time: 3:17:15 PM - 3:24:41 PM (446 secs, 00:07:26) Batt. time : 449 secs, 00:07:29 Elevation(GPS) : 0 1.23 18.033 m (min/avg/max) Altitude(Barom.): -0.25 10.18 38.6 m Vertical speed : -2.45 -0.08 2.57 m/s Max speed : 20.8 km/h Max target dist.: 5.5 m Sats : 10 10 11 Voltage : min. 21.6, max. 25 V Current : 0.5 59 112.5 A Wattage : 11 1345 2542.5 W Capacity: 7276 mAh Motor1: 0.0 8.2 12.3 A Temp: 22 26 30 °C Motor2: 0.0 8.1 12.9 A Temp: 18 25 32 °C Motor3: 0.0 6.6 12.3 A Temp: 19 24 31 °C Motor4: 0.0 7.0 12.8 A Temp: 19 27 32 °C Motor5: 0.0 6.7 14.0 A Temp: 18 24 31 °C Motor6: 0.0 5.9 11.8 A Temp: 18 26 30 °C Motor7: 0.0 5.5 11.4 A Temp: 21 26 30 °C Motor8: 0.0 8.8 14.1 A Temp: 20 27 31 °C Magnet Field: 103 108 117 % (ok) Magnet Inclination: 57 64 71 deg No errors found
Nice...and glad to hear the back up GPS worked fine. Couple of questions for you: How wide did you have your 17-40 set at? I'm curious to know what focal length was when you were still catching the booms from time to time. Also, are you running 550mm booms now or something smaller? Did you check your hover throttle for this weight? I am just guessing that it is probably somewhere in the 60 or low 60s based on the amp draw of the motors. Somewhere around 4.3 amps should be 50% throttle on your motors and just under 8 amps should be 65%. What is interesting, is that at 22 pounds and the numbers from your GPX file it looks like you are not loosing very much efficiency at all from the X8 set up. The way I was looking at it is that if you are 22 pounds, your motors would probably have to have the thrust of a 25 pound flat octo which would put them averaging 8 amps each...and you were definitely not averaging 8. This is encouraging for the one I am working on! Thanks for continuing to share all your info.
Yes, very happy that it wasn’t something more serious! The 17-40 was all the way out to 17. That’s why the boom and motor were showing. I’m running 500mm booms. In real operation I’d probably have the camera tilted down, so this won’t be an issue, and mostly what this lens will be used for is stills, not video. Not partial to the super wide perspective in videos. I’m not sure I put a huge amount of stock in the throttle numbers. Don’t quite understand the focus on that. I’m more concerned with current draw, voltage and temperatures. The throttle is fairly high, but I didn’t measure it on these flights. I do know that I flicked on AH, and I forgot to set it to “0” (automatic) so it leaped up rather dramatically, as I had the throttle at probably 60-70 or so. I prefer to have AH be automatic so I can just let go of the stick after I engage it. My pleasure.
I figured you were pretty wide on the 17-40. I fly full frame sensor Canons as well and for stills I have found myself putting on 20, 24 or sometimes 28mm prime lenses to shed a little weight. And, if only for stills, I have dropped down from the Mark III to a 6D as it again cuts off another 1/2 pound. I used to fly a Mark III and a 16-35 and now I mostly fly a 6D and 24mm. As for the throttle percentage and why it gets so much attention from people, I can share what I know and have experienced with you. I think the general rule on flying multi rotors is you want to have at least a 2:1 thrust to weight ratio. I'm sure there are many reasons for it, but I experienced a few of them recently when flying a smaller X8. When I decided to try out the X8 concept, I built up a smaller one (350mm booms) and used a FC that another pilot I fly with had sitting around. It was a HoverFly Pro. I had not previously flown HF before but we thought we would give it a try. We were flying some smaller motors (Tiger 4010s), 14 inch props and the AUW was not very much. When flying it in 15mph winds we had lots of yaw trouble and some other control issues...never crasshed, but had some dicey moments. As it turns out, we were flying a higher hover throttle. And the hover throttle in calm conditions is lower than in winds since 1/2 of the motors have to run faster to stay pitched into the wind while hovering. Then, if you need to yaw, 1/2 of the motors will need to spin up faster to yaw the copter while hovering pitched into the wind. Add an unexpected gust, and the copter will end up rotating on its own because it runs out of yaw authority. I know this after spending a lot of time on email and the phone with HoverFly thinking something was wrong with the board or I was unfamiliar with getting it set up and dialed in properly. I finally got someone to explain to me that in the event you are using a high throttle to hover, are flying in wind and have unexplained yaw issues; that it it the FC prioritizing altitude and pitch over yaw because it can not do all of them in the current flight conditions. Add to that your battery voltage is lower towards the end of your flight and it makes your descents that much more critical if you ever come down a little fast and have to power out of it to keep control. So that made sense, but the one difference with HF is that it uses the motor mixer concept of spinning all the top props one direction and all the bottom props the other direction. Since the bottom props are a little less efficient it starts with less yaw authority in one direction to begin with. DJI does this as well, but you can set up a custom motor mixer and spin them like MK does. Anyway, that is the reason I have been so focused on making sure I have plenty of head room in my thrust to weight ratio or hover throttle percentage. The difference between 15 and 16 inch props would give you a 20% increase in power if you were looking to make any changes to add a little headroom.
Thank you for taking the time to write that, Michael. Fortunately, I think the MK mixer is considerably more stable than the others’ coax mixers. I can’t imagine that the DJI or HFP mixers are all that efficient or stable. WRT thrust with 15” vs. 16” props, Jim from MontoRC said that my motors are best with 15” props. I would love to have a set of Tiger 16” props to test with but I have to wait another week and do some more testing with what I have. I’m also curious about the fact that the motors are pulling a fraction of their capacity, yet the throttle’s quite high. I’m wondering about the throttle curves or the MK BL configs. Going to noodle this out a little.
Steve the footage stills looks very good. My biggest concern for staying close to 50% as possible is so that if the copter suddenly drops you will have enough horsepower to prevent a crash. Not only that but you also have to think are the electronics built to take a 1600 watt spike for 3-4 seconds? Let's say for example you are flying in AH and then switch it off, but you become momentarily distracted by birds flying around your copter and you lost your concentration and your left hand is no longer ready to be on top of the gas, the copter can drop pretty fast especially at 22 plus pounds. If your hover throttle is close to 70% you may not have enough power to recover depending upon how high you were when you disengaged AH. Another thing to think about is what kind of power spike would the copter see if you have to make a quick response like this? Yes I agree your current numbers are outstanding but what would happen if you suddenly have to give it 100% throttle for 3-4 seconds when its descending like a rock? The power load on the copter will be significantly greater when the copter is dropping like a rock compared to just giving it 3-4 seconds of throttle say at first start up on the ground. Even if the electronics can handle it will you have enough battery reserve to supply the electronics at the time? I guess it depends on how much your batteries have discharged. Again IMO its taking chances that you don't need to especially when you are talking about the possibility of 22 pounds falling at 100 feet. Another thing to think about is motor RPS. I will admit I am not a RC motor specialist but going by traditional wisdom every motor is designed to spin at specific RPM for "normal" operation. Just like a car engine. Is a motor going to live longer driving down the highway at 2000rpms or at 4000 rpms over a period of 50,000 miles? What kind of effect can it have on bearings, and motor windings If the motors RPMS are spinning faster (during normal use) than designed over a longer period of time can the motor be vulnerable to a failure in flight? Maybe yes? Maybe no? Do you want to take the chance when you don't need to? At the very minimum it would a good idea just to check and see where you are with the 5D so you have a reference.
Hover throttle looks like 67-69%. What’s interesting is that my copter’s power system seems to have a considerable amount of overhead based on the rated capacities. By that I mean that the throttle itself is at 68%, although the current draw is about 7.8A per motor, which is about 30-40% of what I think the practical redline is. So by that equation, is there a misconfiguration somewhere? I mean, if the throttle curve is linear, max throttle would be at about 150% on my sticks. All that said, it actually looks like I should invest in 16” props at the weights I’m flying. As the title of this thread indicates, I was originally targeting 8-10kg for this build, and now I seem to have settled at 10kg. So before I have to upgrade my motors (which will require bigger props, anyway), I think I’ll try that. Anybody want to buy a set of super clean Tiger 15s?
Well the power consumption seemed to be an estimate so can the current measurement be an estimate? I really don't know. I would think that the throttle curve is linear because the numbers are linear in respect to position but I'm sure the acceleration curve of the motor isn't linear. Every see the torque curve of a typical engine. It's usually far from linear.