3DR IRIS with 4S batteries

Due to the rather poor flight performance of the 3DR IRIS with Gimbal and long legs on 3S batteries, I was looking into flying with 4S batteries, along with reducing the weight of the quad. In this post I want to share my interim results.

Note: These are interim results as I’m still working out some quirks. Also 3DR has not officially approved this flight configuration. Try it at your own risk!

Note: Do not use 4S batteries with the new IRIS+. On the IRIS+ 3DR has replaced the previous 850kV motors with 920kV motors. These motors are unsuited for usage with 4S batteries. The propellers would spin faster than their specified maximum.

Reducing weight

The only approach I’ve taken so far to reduce the weight of IRIS is by using 3D printed tall legs from dingprint.de. They are lightweight, yet robust enough. A set of 4 legs weights 38g and therefore as much as a single leg of the stock 3DR legs. See more about these legs here under Update 9.
While these legs are produced and shipped from Germany, you can purchase similar legs in the US. Contact promo@impconcepts.com and ask about the 6″- Custom Blue 3D Printed 3DR IRIS legs.

The all up weight (AUW) of IRIS with these legs as well as the 4S battery (more on this later) is now 1659g.

Going from 3S to 4S lipos

4S lipos use 4 cells in serial and therefore reach a nominal voltage of 14.8V. If you increase the battery voltage by 33% (3S to 4S) then you are effectively increasing the motor speed by 33%. To keep all things equal you need to decrease the prop size to match this increased motor speed and prevent the motors from heating up. Once at the same wattage (roughly the same speed and thrust in flight) you would draw 33% less current, and therefore  get about 33% longer flying time. The reasoning behind that is: Watts = Volts x Amps. Thus increase volts by 33%, then drop amps x 33% for same watts.

If you don’t decrease the prop size, the faster spinning prop will generate a lot more speed and a lot more current, increasing the watts very significantly. The resulting effect will be a higher powered (lower hover throttle) quad, with a higher current draw (resulting in shorter flight times). You may also run the risk of overheating your motors or drawing more current than the ESC can handle. This is obviously not desired. Although we do want to increase the power slightly vs. the 3S config.

Also keep in mind that not all equipment can handle the higher voltage of 4S batteries. The Tarot Gimbal cannot handle this voltage and therefore needs a voltage regulator. If you are using additional FPV equipment, you also need to check if they can handle the maximum 16.8V that 4S brings.

Material for testing
For testing IRIS with 4S batteries, we need a 4S Lipo, but also smaller propellers. Here is what I’m using for the tests:

  • ZIPPY Flightmax 3000mAh 4S1P 20C from HobbyKing. This battery is very cheap and delivers roughly as much wattage as a 3S-4000mAh battery. It fits the IRIS battery bay perfectly and already comes with an XT-60 plug. I already own a IMAX B6-AC Charger/Discharger, which is capable of charging these batteries without any issues.
  • APC SlowFly 9×4.7 Pusher and Puller propellers. They are basically the same propeller as the stock propellers that come with IRIS, except that they are 9″ in outer diameter instead of 10″. As they use the same spacer rings for the propeller shaft, you can even leave your current ones on IRIS.
  • Voltage regulator from 4S (16.8V) to 12V. The Tarot Brushless Gimbal is recommended to be operated with 12V and cannot handle voltages higher than 14.8V. We therefore need to place a voltage regular between the 4S battery and the Gimbal. This will reduce the voltage from up to 16.8V on the lipo side to 12V for the Gimbal. As the Gimbal only draws a maximum of 500 mA, the linked voltage regular is a perfect choice. Also the regulator already comes with the right plugs, is very small and lightweight.

Crunching the numbers

Before heading out to the flying field with the IRIS, 4S batteries and 9×4.7 propellers, lets crunch the numbers in eCalc xcopterCalc and see what to expect. With xcopterCalc I will also include an APC Slowfly 10×3.8 propeller. This propeller has the same length as the stock IRIS propellers, but a different pitch.

While I have already shown all values that I use for eCalc xcopterCalc in a previous post, this time I also want to include expected motor temperatures. Here you can chose between “Excellent”, “Good”, “Medium”, “Poor”, and “Very Poor” with “Medium” being the default in eCalc. It is hard to determine the correct setting here. the best approach is to measure the real motor temperature during test flight and re-verse calculating it. For now I’ll stick to the setting “Poor” due to the motor pockets of the IRIS arms.

While I managed to reduce the weight as written before, I’ll still crunch the numbers with the stock weight of IRIS with 1692g, just to have some safety buffer – e.g. for installing FPV gear.

With that here are the results:

Figure 1: eCalc simulation of 3DR IRIS with 4S battery

Figure 1: eCalc simulation of 3DR IRIS with 4S battery

We can see that the stock 10×4.7 propeller is not a good choice. At low outside temperatures we run the risk of drawing more ampere during full throttle than the ESC can handle. Also the expected motor temperatures become higher quite quickly.
Both the 10×3.8 as well as the 9×4.7 propeller will provide decent hover throttle values at Normal and Low battery. The 9×4.7 propeller provides slightly more promising motor temperatures at max throttle. These temperatures are expecte to be only slightly higher than with the stock 3S-3500mAh configuration.

Bench testing

Next comes the “bench testing”, flying IRIS with 4S-3000mAh batteries and 9×4.7 propellers. For this I attached the IRIS – via chopsticks – to a laundry drying rack on the floor. That way I can simulate a “flight” indoors without IRIS actually taking off (See Figure 2).

Figure 2: Bench-testing IRIS with 4S batteries

Figure 2: Bench-testing IRIS with 4S batteries

With this test-setup I hooked up IRIS to Mission Planner in order to monitor voltage, ampere, and hover throttle. Next I armed IRIS and gave enough throttle to have lift up and be held back by the chopsticks. This could be considered hover throttle. See Figure 3 for the throttle curve for one sample flight.

Figure 3: Hover-Throttle during bench test

Figure 3: Hover-Throttle during bench test

During these test flights the motor did not get noticeable warm and only reached a temperature of about 30C, which matches roughly the expected result. I measured the temperature with a contactless IR thermometer.

Outdoor flight test

Next on the agenda were outdoor flight tests with the 4S-3000 mAh and 9×4.7 propellers. For this I loaded the Iris with Tarot Gimbal parameter file and performed an Auto Tune once airborne. Also I configure the THR_MID parameter to be 570, in order to better match the expected hover throttle.
Be aware that with the 4S battery IRIS behaves much more sensitive on the throttle stick. You can feel the “power” that IRIS has now – despite the weight of the Tarot Gimbal and tall legs.

My full parameter file for IRIS with Gimbal and 4S-3000mAh batteries can be found here.

Outdoor flight tests were very successful. I was able to use multiple 4S-3000mAh lipo to repeatedly fly an Auto mission for about 8-9 minutes per battery. Afterwards remaining Lipo capacity was at about 30%, which provides a very conservative buffer. Reducing this buffer to about 20% would probably add another 1 minute of flight time. During the entire flight the throttle remained around 58% – 60% for flying – not hovering (Figure 4).

Figure 4: Outdoor flight test

Figure 4: Outdoor flight test

The entire log for this flight can be found here. After each flight the motor temperature was around 32-34C, while the outside temperature was around 20C. This again roughly confirmed the eCalc xcopterCalc numbers.

With the 4S battery IRIS with long legs and Gimbal flies similar to IRIS with short legs and 3S batteries. While it’s still far from an Acro-Quad, you at least can’t feel the weight dragging IRIS down anymore.

10×3.8 Propellers

I also tested flying IRIS with APC SlowFly 10×3.8 propellers. These propellers have an outer diameter of 10″ – just like the stock propellers that come with IRIS. But the pitch is less with 3.8″ per full rotation vs. 4.7″ per full rotation with the stock propellers.

Comparing the flight behavior of IRIS between the 9×4.7 configuration and the 10×3.8 behavior, here are the main differences and benefits of each configuration.

With 9×4.7 propellers

  • Flight time 9-10 minutes up until 20% battery remaining
  • Motors get moderately hot with about 35C at 20C outside temperature
  • The quad performs very well in windy/gusty conditions and drifts off less from desired path/location

With 10×3.8 propellers

  • Flight time 10-10 1/2 minutes up until 20% battery remaining
  • Motors get hot with about 45 – 50C at 20C outside temperature
  • The quad is susceptible to windy/gusty conditions and drifts off from desired path/location due to the larger propellers acting like a sail.

With this I personally prefer to fly the configuration with a 9×4.7 propeller, due to the superior performance in windy conditions.


IRIS with Gimbal and tall legs behaves quite well flying on a 4S-3000mAh battery and 9×4.7 propellers. Hover throttle is within a reasonable range and IRIS has enough “power” to fly around without any issues, even towards the end (30% remaining energy) of a Lipo. Fligh time is decent while not great with 8-9 minutes. You can further increase flight time by about 1 minute by reducing the Lipo safety buffer to 20% remaining energy at landing, giving you a total flight time of 9 – 10 minutes.

While there are other ways to improve the flight performance of IRIS, the benefits of the approach shown here should be clear: It requires very few investments into a new 4S-3000mAh lipo and 9×4.7 propellers. It also requires a minimal work to be performed with swapping only the propellers and battery. No soldering is required as it would be with e.g. changing the motors.

What’s next?

With the 4S battery IRIS behave very sensitive on the throttle stick. You can feel this while flying in Stabilize mode. I have attempted to compensate for this by reducing the Throttle acceleration controller P and I gain. Unfortunately I have found contradicting reports whether the Throttle acceleration controller P and I gains actually affect Stabilize mode or not. If they don’t, I will need to look into R/C transmitter curves.

The flight time of IRIS would improve if weight could be reduced even further. This is an area were I would love to hear ideas on how to do this on IRIS without having to rebuild the quad into a new machine.

Also a larger 4S battery could increase flight time. With a 4S-4500mAh battery one would be able to reach flight times of approximately 12 minutes. Unfortunately 4S batteries at this capacity that have the right size to fit IRIS are either out of stock or not available in the US. Other batteries that are readily available in the US don’t fit the size of the IRIS battery bay. Here it would also be great if someone had an idea how to easily solve this.


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29 comments on “3DR IRIS with 4S batteries
  1. witness digital says:

    Hi Christian, for more battery bay room check out my pregnant IRIS thread about using 16-20mm M3 hex standoffs to increase the height of the IRIS battery bay by the same amount.

    good luck and thanx I had just been getting ready to give up on the IRIS..


  2. witness digital says:

    and how are you powering the gimble on 4S? weight of the SBEC used etc?

  3. Paul McBreen says:

    Not being electrically minded, what C rating do the 4S batteries need to be? I was looking at these https://www.hobbyking.com/hobbyking/store/__56840__Multistar_High_Capacity_4S_5200mAh_Multi_Rotor_Lipo_Pack.html
    If the 10C rating is ok, (which I doubt) they would be ideal as they are no heavier than the 3S 5000mAh ones I’m currently using. I’d need to space the battery box because they are a couple of mm to fat, but the flight time would be considerable improved.

    • The C rating of a battery along with the capacity tells you how much current you can draw constantly as well as in short bursts. With the 5200 mAh Lipo above and a 10C constant rating, this means that you can draw 5.2A * 10 = 52A constantly. The Lipo also states that you can draw for short periods of time (usually about 5-10 secs) 20C, which translates to 5.2A * 20 = 104A.
      If you look at the battery that I’m using: It’s a 3000 mAh with 20C constant. That translates to 3A * 20 = 60A constantly. That’s not very far away from the 52A constantly above. And I’ve flown dozens of times with the 3000 mAh-20C Lipo without issues.

      With my 4S setup and my flying style I draw about 15A (Open a log file in Mission Planner and look at CURR->Curr). I therefore would love to use the Multistar 4S 5200mAh Lipo and have been eyeing it since it came out.

      But as you said: The battery compartment of IRIS is just a tiny bit (2-3 mm from what I can tell) too small. I’ve been looking at options of using spacer ring in order to increase the battery compartment, but haven’t had the time to look at this more seriously.
      If you come up with some great ideas, please do share them!

    • david says:

      10c is more than enough juice for the iris! You do not need a high c rating there is no way the iris setup could ever use or need more than 10c! also on the iris or iris+ you never ever need to autotune them period! they are well thought out and autotune is for custom built multirotors to get you well into the ballpark and after a proper autotune on a custom rig when done properly there is very little pid adjustments needed unless you are realy getting technical doing prox flying or to be honest just anal!

  4. Paul McBreen says:

    My Current batteries are 27mm and they are a tight fit, see here https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11956
    so I expect I’d have to “Fatten” the Iris to fit the multistar in as they are 29mm, But as they are light in comparison to higher C rated batteries and have good capacity, I think I’ll give them a try. I need to gain about 5mm to have a comfortable fit that allows for a bit of expansion and/or dimension error, or I could get some longer screws and just use a couple of washers to space things a bit. I’ll pull it apart tonight and have a look, But I think there’s an easier way than this
    Might work better on the bottom of the arms, and a piece of Nylon/plastic cut and drilled to the right size would work better than the standoffs

  5. hotelzululima says:

    Hi paul,
    look for pregnant IRIS in the ardupilot IRIS forums where I use threaded standoffs to to achieve 16-20 mm of additional battery compartment height at the advantage of having the compartment gapped and open, MUCH better for battery and 4/1 ESC cooling by the way(IRIS is VERY poor in that regard)..


    • hotelzululima says:

      oops did not see where you had already done that please disregard above

  6. Paul McBreen says:

    I pulled the Iris apart to see the best way of making the battery box bigger. Doing it on the bottom of the arms, I found that the LED wires are very short, but as I’m dropping the lower section it shouldn’t matter, I do think the LED wires have a limited life span. One thing I’m going to do is make a couple of slots in the door for the battery wires and plug the battery in outside the door. This will mean no need to shorten connections or squash wires in with longer batteries. I have already cut some of the foam out of the battery area to fit the 3S 5000mah batteries in. As the 4s batteries will have the right plug and some length to the wires, this should work well. COG will need to be checked. I can move the Video transmitter forward or back to achieve this, or the battery itself. I’m going to find some plastic sheet the right thickness 3 to 5 mm and make some spacers next. I think I’ll order the batteries and regulator this week. Theres a lot of batteries that are 33mm that would fit, as 27mm batteries are tight, it might be best to go straight to 5mm extra. I will need to get/find some longer screws.
    If the throttle is sensitive after the addition of 4S batteries, whats the yaw like? I find mine is to touchy now and I get jerky video when ever I rotate the Iris, unless I’m very carefull. Any hint on what setting to change? Or do I do it with radio Expo?

  7. Paul McBreen says:

    Hi, Well I’ve ordered 3 of the Multistar batteries and a voltage reg and 9×4.7 props. I’ll be testing it all next weekend. (takes a while for things to arrive in New Zealand)
    Should I do the autotune like you did? or is it safe/easier to just use you parameter file as a start?

    • Awesome! Let us know how your tests go. I would recommend that you definitely change the he THR_MID parameter to be 570 before your first flight with the 4S setup. That way your throttle stock will be roughly in the mid-position, allowing you to use Loiter and AltHold mode. With that it’s really up to you if you want to take over my settings or run a quick AutoTune. It might be interesting if you run an AutoTune and compare the values to mine. As you are using a different battery (with different weight) they will most likely be slightly off.

  8. Paul McBreen says:

    I’ll be using the battery box spacing technique show in the link above, was pretty much the direction I was heading in

  9. hotelzululima says:

    hmm heading to Brills i the morning for a locally sourced LM7812 VR 3 terminal VR that plus a .33 and a .1uf bypass cap(s) some heat shrink and some jst connectors will have a 12v reg in my hands fastest and I suspect is what the source listed above has done and despeced to .5 am instead of the usual 1.8A it can handle heat sinked.

    more tomorrow

  10. Paul McBreen says:

    Well I finally got time to sort the quad out and get it running on 4S batteries. I brought 3 of the Multistar 5200 4S batteries from Hobbyking and 9×4.7 props. I got a voltage regulator from readymade Rc so I didn’t fry the gimbal feeding it 4S voltage. The immersion rc video transmitter can handle the voltage ok, so its plugged direct. (I have a Tarot 2D gimbal and Gopro on it)
    I set the THR_MID parameter to 570. I have found that I need a bit more than half throttle to stay level in stabilize mode, so I’ll have to change it a bit (I assume I should go a bit higher?) I did an autotune and it seems to fly pretty good, seems to be a bit faster and certainly climbs much quicker. Absolutely thrashes my mates Phantom 2 in the speed and climb stakes.
    I have done 50minutes flight time today with 4 batteries (used one twice, none to below 30%) 12 minutes seems to be easily obtainable with 40% showing. I tested the batteries with a proper battery tester and it was showing 35%, so not worried about the 5% difference.
    I’m very happy overall.

    Just so you know, I found the easiest way to get the extra height for the fatter batteries was to space the bottom plate with 8 M5 nuts. I used slightly shorter screws and screwed it up with the bottom cover off. I then held the bottom on with the Gimbal screws. seems to work very well.

    • Paul, this is fantastic news! I would recommend you do a pure loiter test-run to see what loiter times you get, but also in order to determine the THR_MID value. Take off, start your timer and place IRIS in Loiter at about 5m altitude in a wind-shaded place. Don’t do anything, but wait until the voltage reaches 14.0V (which is the 4S equivalent to 10.5V on 3S and should be your failsafe voltage). Than land right away and stop the timer. You now have your hover time, which should be longer than the actual flight time. But it’s also the time that vendors promote as the “flight time”. When you open the log files and look at CURR->ThrOut, you’ll see the hover throttle IRIS used. Notice that it starts at a lower value and then raises slightly as the voltage drops. Add the value from shortly after take-off with the one shortly before landing and divide it by two. I would recommend you use that number as your THR_MID value. Let me know what hover times you get with the 4S-5200 mAh.

  11. Paul McBreen says:

    I’ll try to get a chance to do that next weekend, its still getting dark pretty early down here, so I wont get a chance after work to do it this week. I haven’t sorted out opening log files yet, I’ll have to study up how to do it.
    I did about 1.5hrs flying based off the Gopro videos over the weekend. Only one small mishap when a prop nut came off. Luckily it landed from about 5m in a flax bush so no damage. I now have some shiny new nylon lock nuts as well as the serrated washers, so that shouldn’t happen again. 30seconds before that I was over water!
    One thing with the 10c rated Multistar batteries is there slow charge time. They will only suck 3.3amps max from the charger (I’m setting to 5amps) and it just falls from there.
    Here’s a link to some footage from the weekend http://youtu.be/48TJj6cXapk?list=UUeaUMPPzM-WA-PFKr4CLq0w excuse my rough flying, I’m really struggling with the touchy yaw. any help on what settings to change to fix that would be appreciated, either that or I’ll buy a 3D gimbal. I’m going to put the motor power settings up a bit on the gimbal to stop some of the twitchs

  12. You could look into configuring a curve in the R/C transmitter. I’ve not done that and unfortunately have no pointer at instructions on how to do that. After a while I gut used to the more sensitive controls. It’s bit like driving a sports car, after having driven a truck or SUV for a long time. 🙂
    What charger do you use? With the Imax B6 I can never charge at more than 3.3A. That seems to be the limit of the charger, irrespective of the Lipo. I ended up buying a second charger, so I can charge two batteries at the same time. And sometimes I charge 2 batteries in parallel per charger. That doubles the charge time, but I don’t have to swap batteries in between. Just hook everything up and a few hours later I have 4 charged batteries.

  13. Paul McBreen says:

    i have a Hitec multi charger, it can do 4 batteries at once at up to 6amps each. I used to race RC cars so I have things like this lying around.
    older model of this http://www.amain.com/Hitec-X4-AC-Plus-Four-Channel-AC-DC-Multi-Charger-6S-6A-50W-x-4/p214203

  14. Peter van der pol says:

    Dear christian,

    Thanks a lot for the great post…as a fairly new iris owner I really got some good answers from this topic. I also used the spacers for my battery compartment. I will be able to use 4000mah 25c lipos or bigger now im using the 12mm spacers.

    I also got the voltage regulator, but where did you place it?i will be using a dys 3-axis gimball and some fpv equipment. Could you share some photos or information about the location of the regulator? Did you had to strip down the entire iris to get to the powerboard?

    Thank you in advance,

    • I’ve placed it at different positions throughout my trials of adding equipment: One place was outside the shell, right next to the Gimbal. Another location was taped to the bottom plate, next to the ESC’s heatsink. And yet another place was tucked in the side between the bottom shell and the battery bay. In all cases I had to remove the bottom shell to install it. Also while I was initially flying with my FPV transmitter of the main battery via a Y-cable, I have in the meantime moved to powering it via a separate LC-protected lead from the balance plugs. That way I can choose at each flight if I actually want to power up my FPV TX. Hope that helps.

  15. Paul McBreen says:

    What I have done is splice another power connector into the Gimbal power supply, I plug my transmitter direct into that and a voltage regulator between it and the gimbal. its a nessy bunch of wires cable tied and stuck to the underside of the iris with 2 sided tape. I’ll tidy it up and shorten wires etc one day… I hate soldering, so I’ll buy some new plugs and add them in. Its nice to be able to plug and unplug thinks when ever you want so I wouldn’t ever hard wire them.

    when it stops raining here I’ll go do a flight time test, I’m expecting over 12minutes in a hover.

  16. Paul McBreen says:

    Today was a bit windy for doing flight time tests, but I managed to find a sheltered area to give it a go. I kept the Iris pretty close to the ground, about 2.5 to 3m to keep out of the wind and left it in Loiter mode. I did re position a couple of times, played with yaw a bit as I was bored and the wind shifted so I wanted to get out of it. It was really still quite windy but it has given me a really good indication of flight time with the 4S Multistar batteries and the full FPV setup running.
    So full spec
    Battery, 5200 10C 4S Multistar, tested at 98% before plugging in
    9×4.7 turnigy mixed carbon props
    Gopro 3 Black on Tarot 2D Gimbal. Camera on and recording, powered from Transmitter
    Transmitter is an Immersionsrc 600mw
    14m10seconds at 30% battery, ran it to 20% and hit land, 16m11s total flight time. Test afterwards said battery is at 14%, 14.8v. which is a bit lower than the Iris said it was, so I’ll be landing at 30% indicated in future, so thats about 14minutes. Battery was a bit warm after being run down to that level. I’ll have a look at the logs and see what the throttle setting was during the test

    Overall, a significant improvement on the standard setup and the Iris now performs very well indeed. I suspect I would get another minute in calm conditions. there was quite strong wind at times that it was fighting. I’ll happily plan 12minute flights based on this test.

    • Peter van der pol says:

      That’s great!! Wow, if I could do the same that would be great. I wonder what is different with you frame as mine, it is a regular iris right? Not a plus?

      I’ve also used the spacers, so I now have plenty of space. No large legs or gimbal added and I’m currently including full FPV at 15xx gram. I get maximum 10/11 min flight time with 4000mah 25c lipo.

      May I ask what the full equipped weight is? I expect mine to get 1900 gram.

      Like to hear from you! Thanks so much.

  17. Michel says:

    Hey, it’s some time ago the last time you replied here but I will try my luck. I just received my IRIS+ and I am searching for some stronger batteries to improve flight time. Also I am looking for a battery charger which can charge them faster.

    Could you give me some information, which batteries would the the best for the IRIS+ and which specifications (like mAh or Voltage) are important so that i do not destroy the IRIS?

    Thank you very much!

    • Christian Elsen says:

      The stock 3DR IRIS+ batteries (3S-5100mAh) are actually the best ones I could find. I use 6 of them right now. None of the other lipos I tested came close to their performance.
      The Turnigy Multistar 3S-5200mAh were just horrible. Their voltage started to sag pretty badly after a few cycles.
      I also tried some Lumenier 3S-5200mAh. While they provide a bit better performance than the 3DR, they are also a bit heavier, thus negating the effect. As the Lumenier are a bit more expensive I ended up sticking with the 3DR.

      With regards to a charger, I recommend the HiTec 44167 X4 AC Plus 4-Port AC/DC Multi-Charger (http://www.amazon.com/gp/product/B005MW0WZO/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B005MW0WZO&linkCode=as2&tag=edgclo-20&linkId=6A43J5CHRBQ5OXXB). It lets you charge 4 of the stock 3DR batteries at 1C in parallel. This allows me to charge the 4 IRIS+ batteries in about 80 minutes.

  18. Peter van der Pol says:

    Hi Christian,

    I Still fly a 3DR Iris, it is upgraded with the spacers so I can use larger battery’s. I’ve used it a BEC zo I can also make use of 4S lipo’s.
    The drone has a weight in total of 1560 Gram, this is including FPV equipment and 4S 4000MAH Zippy Compact 25C series, shortlegs – No gimbal

    I’ve experimented with these battery’s but It seems like I cannot get a higher flighttime then 11 minutes Hover en 10 minutes free flying. (I’ve made a excelsheet to register my runs). In this case I use for testing purposes 9″ x 4,7 Gemfan props.

    Because I would like to add some upgrades which will weight including camera around 350 gram, I fear it will get too heavy:

    # Retracts – 130 Gram

    # Feiyu Tech 3 Axis Mini gimbal – 149 Gram (excluding camera)

    Could you advice me in this? I wonder if the old Iris is still the way to go? I like this IRIS because I can swap Lipo’s between different drones.

    Hope you can help me out, I love 3DR , I love the IRIS, but I hope It can handle the job. Looking at a flight time of 10 min.

    Peter van der Pol

  19. James says:

    Guys…. Hands down THE best thread I have found on the IRIS. I have had nothing but trouble since day one with mine. Man I wish I could have you both in the same room to pick your brains… because this one was about to have the pixhawk taken out of it and the rest thrown in the bin. Thanks guys