Has anyone considered or tried 11 inch props on the Iris? What about 3 blade or 4 blade props?
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Has anyone considered or tried 11 inch props on the Iris? What about 3 blade or 4 blade props?
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Hi Mark,
Great idea, after what you've been through, building your own is the next logical step.
I never recommend it as a first step, but there isn't any reason you cant put together a really good one.
I think the Iris was well intentioned and has some nifty design features, unfortunately it also has a few significant design flaws and a some inadequate components.
A few recommendations:
You want to haul a GoPro Camera and a Brushless Gimbal and you want at least 10 minutes flight time.
So that defines the envelope you want to work in.
From what youve said you'd also like something reliable and as trouble free as possible, but with lots of capability.
While the Pixhawk isn't trouble free it is still the best thing you can currently buy so keep that.
The smallest thing you can get that will actually work the way you want it to be would be the Hoverthings FLIP FPV Pro frame, a Dead Cat and it is a good deal (and there is a trick).
http://www.hoverthings.com/frame-sets/flipfpvproblackorange.html
Normally it will only take a maximum of 10" props, but they now have listed availability of oversize arms that will take up to 13" props.
http://www.hoverthings.com/parts/flipfpv/fliparmblack-397.html
My freind Oliver is flying one of these with a Pixhawk, brushless gimbal and GoPro with 10" props and it is fantastic, he gets about 10 minutes flight time.
The very low profile of a dead cat means that even in 15 mph gusts, it hardly moves at all and the GoPro on a cheap brushless gimbal is rock steady.
If you upgraded to 13" props (he will when Hoverthings opens again after vacation too) you probably have about the ideal GoPro/Gimbal platform.
This is a better format than X because it is so flat and so unresponsive to wind.
I would also suggest the KDE 2814XF 515kv brushless motors as these are probably the most efficient 4 cell motors you can currently buy in this size class for 13" props.
http://www.kdedirect.com/KDE2814XF515.html
They are also extremely well made and have a stack of 3 ball bearings instead of 2 like everybody else.
These are what I am using on my custom and I think they are the best available at this size period.
Put some decent ESCs and a 5000mah (or bigger) 4 cell battery on that And you should be able to get an easy 12 to 15 minutes out of it and it will fly like a Sports Car and hover like a tripod mounted on the ground.
Put a 7000-8000mah MaxAmp 4 cell battery on it and you should be able easily exceed 15 minutes and maybe up to 20 minutes.
You should be able to keep the whole copter / battery / camera / gimbal to below 5 pounds and if so it will hover at less than 50% throttle with 13" props and the listed KDE motors and your g/w efficiency will be better than 15 which will give you excellent flight times.
Take a look at my quadcoptersarefun website to check out Oliver's Flip FPV Pro build:
http://quadcoptersarefun.com/2FlipsBuild.html#FlipFPVProBuild
If you want to build conventional X frame, the Tarot F650 Quadcopter frame is a CF tube frame that is quite popular and relatively inexpensive.
http://www.helipal.com/tarot-fy650-quadricopter-frame-set.html
It will get pushed around in the wind more though and will not have quite the snappy performance of the Flip FPV Pro.
A lot of people are flying the FLIP frame and the similar but more expensive TBS Discovery Pro (I think the Flip is better because of those nearly indestructible CNC milled fiberglass arms.
I have crashed my Flip sport into everything you can think of including trying to cut down an 80' black pine tree with it (unsuccessfully) and have succeeded in breaking only a few props.
Best of luck,
Gary
Hiya.
Coming to this a bit late.
So for iris + Gimbal a lot of the problem is those heavy legs. Ive been pointed to this site and have ordered these. It may help:
http://www.dronehoners.com/
Batteries I use the 5000Mah 3S zippy as mentioned here already.
http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8583
Much better than the supplied 3500 3s (which tend to over heat Im finding)
I notice on hobby king there is a 5850Mah Zippy that would fit the bay also. (maybe better since shorter) and higher C rating
http://hobbyking.com/hobbyking/store/__9932__ZIPPY_Flightmax_5800mA...
Props Im testing quite a few:
I like these ones at the moment. They are cheap ass and nasty..but look and sound kool haha
http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=39773
Here they are below. This setup was over heavy and didnt fly well :P
Ive got no figures to make any of this post worth reading tho :)
Maybe next outing I can time it.
-P
Oh
1 hour after I posted my Legs arrived from http://www.dronehoners.com/
Took about 1 week delivery. They are very light!!!! Seem to be a clear perspex material.Look forward to testing them!
-P
Even though I don't own an Iris (and by the look of the threads, probably a good decision) I have a bunch of other quads and think I might be able to offer sound advice here.
If you are going to use a GoPro with or without a gimbal, you really need to go to a 4 cell battery, not so much to increase your flight times, but just to have sufficient performance to fly properly with the Iris.
With GoPro and gimbal it is a very widely known fact that the Iris is seriously under powered and you really want to hover at about 50% throttle - just to be safe and have proper control.
You also need to use 10" props.
Don't forget a 4000mah 3 cell battery has the same total energy as a 3000mah 4 cell battery, but the flight time with the 3000mah 4 cell battery will not be as long as the 4000mah 3 cell battery because the motors used on the Iris are not as efficient at 4 cell hover speed as they are at 3 cell hover speed.
However, the 33% stronger thrust you get from 4 cell will allow you to use a larger 4 cell battery if you can stuff it in there.
On 4 cell you will need to watch motor heating and ESC heating more closely although I haven't heard of much problem with the Iris.
If the Iris had been made to accommodate 12" props with motors to match it would have been a much more capable copter.
As it is 10 to 12 minute flight times are probably the most you should shoot for with 4 cell battery, GoPro and Gimbal, adding more battery would impact performance more than it would help.
Maybe with excellent setup and a MaxAmp battery of the appropriate size you could squeeze out 15 or 16 minutes.
(MaxAmps can commonly supply 25% more energy per unit weight than the other common batteries so you could go to a 25% higher MAH rating for the same weight.)
Just my thoughts, I am not an Iris guy but I am scratch building a CF tube H - Dead Cat with 515KV KDE motors and 14" props that I fully expect to actually be able to get 30 minutes usable actual flying around time out of with GoPro, Gimbal and FPV.
Just trying to help you tweak the Iris to get the most it has to offer.
General rule - bigger props and high quality lower KV motors = considerably higher efficiency and longer flight times (cost more too).
Hope this helps, took a long time to understand right.
Gary,
Great advice. I will look closely into your build. Please keep us posted cuz I am going to build another. I am prepared to spend the extra money on better motors and other stuff. Right now I have some more immediate needs from the Iris and will keep tweaking. Problem with 4 cell is finding one with adequate capacity that will fit into the compartment. In addition, my motors get extremely hot with the 3 cell.
All I have ever expected from the IRIS is 10 to 12 minutes with go pro and gimbal. Right now that is unobtanium. I feel jilted over the Iris purchase but I am not a person to hold grudges. Only action solves problems.
Back to my flight time issues where the front right motor ESC output is getting maxed out causing the other motors to back off in an effort to maintain attitude.
According to jschall in the log analysis forum, I have COG issues and closely studying I have come to agree with him. Hear me out.
I added a mast (see attached pic) because of the myriad of issues caused by the GPS contacting the Pixhawk. I really had no choice. The Iris was totally unpredictable and GPS performance was terrible. Installing the mast solved ALL of these problems providing excellent GPS performance. I then added the gimbal, legs and go pro and it all went to sh(*.
If you look at how I installed the mast, the weight of the GPS and the mast is about 1/2" further forward than the stock GPS mounting position. The does indeed shift the COG slightly forward relative to the stock configuration. Since the IRIS is so under powered this slight COG shift has caused the front motors to work harder to maintain attitude. This upset the delicate power balance of an under powered bird. This shouldn't be. I have seen masts mounted way off the COG and not cause these kind of problems.
This problem could be solved by putting the GPS back into it's original position and moving the PIxhhawk per the 3DR recommendation but I refuse to go back to that setup since the mast solved so many other issues. I am going to experiment with moving the PIxhawk to the back more and installing some COG counterweights. I doubt this will work but I would like to have something to fly while I work on another build. I need 10 to 12 reliable minutes with a gimbal and go pro. My next build is for a downward facing camera and mapping in areas where a plant doesn't work out (golf courses) as well as a copter.
I am also going to order the Nano-tech A-Spec 3s 4500 since it only weighs 278 grams. The Zippy 5000(16 minutes without gimbal, legs and go pro) weighs 404 grams. The A-spec seems to have the highest power to weigh ratio of anything else I can find.
had the stock Iris not had so many issues I would never have tried the mods that has upset the COG but I got tired of waiting on the design change from 3DR. I would say the GPS/Pixhawk contact issue was the major design flaw that has killed the Iris for me. I can assume the ones shipping now don't have this problem. I patiently waited for the consumer version and it just didn't pay off. I would like to try different motors but the arms don't allow any motor with a larger diameter to work.
Gary, thanx again for the advice. Sounds like there is a lot experience behind it.
Mark Prince
Hi Mark, One thing I didn't mention but which is very important for any not fully symmetrical copter is decoupling the roll and pitch rate PID.
Normally they are tied together and have the same values, but the P Value for pitch rate needs to be higher than the P value for roll on a dead cat design like the Iris.
I don't know if default Iris PIDs take this into account, but they should.
The reality is that the wider moment arm between the front and back props versus the side to side props means that less force is required to roll the copter around its center of mass than is required to pitch it around it's center of mass.
There is also a tendency to distribute the primary mass from front to back in a dead cat which actually worsens this situation.
TBS Discovery and Hoverthings FPV Pro type dead cats are probably worse than the Iris because their central mass is very long front to back, but they require very different settings for rate pitch versus rate roll (P value only is usually enough).
Of course with additional mass like camera and gimbal underneath or worse one in front (distributing the mass more linearly front to back) this problem is made worse requiring more difference between roll rate P and pitch rate P.
This actually makes the difference between one of these handling well and not.
I figured out the problem. The fix will be difficult.
First I added 3 ceiling fan balancing weights to the left rear motor shroud to counter the fact that the front right motor is always working harder (according the output of RCOU Chan1).
No change. Bird drops dead at 10.7 volts and gets to 10.7 in 5 minutes with a zippy 5000.
I have noticed for quite some time that the rear left motor seems to have stronger magnetic fields than the other motors. When you slowly move the props with your finger the rear left motor magnets (or magnetic fields) have much more resistance than the other motors.
So I bit the bullet, flipped the Iris upside down, cut the wires and swapped the front right and rear left motors, and soldered them back. What a pain in the arsse!
The problem remains except the rear left motor's output is the one that maxes out causing the others to cut back.
I have one motor that is much stronger (or more efficient) than the other 3 motors. The Pixhaw and ESC is always sending much more signal strength(or voltage) to the motor diagonally opposite the motor that is stronger than the others.
What to do next?
I need better quality motors than the 3dr blue motors. I have another spare motor that I can put on but I have a feeling that the fun will never end as long as I stick with Iris design. I have no issues with any of the electronics. The motors suck.
I would rather install some different motors than ask for a refund and send everything back. I am very confident in the problem solving process I have implemented.
Are there other higher quality motors that that have the same diameter as the 3DR 850KV blue motors? The diameter is 27.6mm.
I don't know how may Iris customers are having severe issues with Iris flight times when the gimbal and go pro are installed but I will bet a paycheck that this could be their problem. It only takes one oddball motor to make this happen.
BTW - I have totally given up on 3DR support with this issue that I have been busting my ass on for months. I'm the kinda guy that likes to go down swinging but sometimes you gotta throw in the towel.
But first I'm gonna take that one really bad ass motor off and put a new spare in it's place and see what happens. If that doesn't work I'm gonna take all of the electronics and wiring out put the whole thing in a hydraulic press and watch the pieces fly!
Mark Prince
Ok. I swapped out the suspect badass motor with a new one. No difference. Rcou chan1 always dominates. I can't even use 2000mah of a 3850 mah battery. I can attach logs but it's useless. Same old story. I am done. Barely 5 minutes (not reliable) after months of diligent testing and soldering with everything I can thing of trying and trying everything 3DR tells me to try. I don't want my money back, I just want to crush it.
the only hydraulic press I have quick access to is only 4" wide. When I find the right one I will post the video. I have already stripped it down and am shopping for a new chassis.
What a ripoff. I will most likely be banned after this message so if you want to keep communicating after this while we build a flyable bird my addy is mprince7596@gmail.com
6 elfin months of frustration. Thanx 3DR for the lessons in what not to do.
All I wanted was 10 minutes with a gimbal and go pro for slight over $1,000 I paid(plus the $400 camera)f. I doubt anyone has put the effort into it that I have. There are other people posting that have that. I wish I knew what the secret is but it doesn't matter now anyway.
mp
Hey mark, they're too wimpy to ban you unless you get really obscene or like that, so stick around. Here's the deal: You sound like a builder, not someone who has to have an RTF quad. So build one. When you buy an Iris or any other assembled or bundled quad you are of course paying for someone else to build it. They in turn need to keep the price within reason, so the tendency is to go cheap-ass on at least some components. And maybe on some labor as well. You can get a whole lot more bang for the buck doing it yourself. Use your Pixhawk and the 3DR GPS unit and lose all the rest. Buy T-Motors, or Scorpions, etc. Buy decent ESCs, either Castle or maybe a 4-in-one. Buy high quality props, like Graupners. Buy a frame. And so on. You'll spend little if any more money, you'll have fun, you'll learn a lot, and you will certainly have 10+ minutes of flight time (suggest Venom batteries, not too pricey and excellent).
Great suggestion. I bout a 3s venom 4000 3s about 2 months ago. Excellent battery in cell balance, bench voltage loss, gives a full 4000. Don't know how long it will last but it's the best I've had so far.
mp
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