Time to retire the DJI F450? Looking for advice

ArduCopter
1

My son and I built a quadcopter, hoping to be able to use it for aerial photography. Some of the equipment on the quadcopter are as follows:

  • DJI F450 Flamewheel frame
  • 3DR Pixhawk PX4 controller
  • DJI 2212/920KV motors
  • 9.5 x 4.25 carbon fiber props
  • E300 ESC’s
  • GPS antenna
  • FlySky FS-iA10B receiver
  • Plastic legs
  • Remote camera trigger
  • Samsung NXmini camera (1" sensor, 20.5MP)
  • Floureon 5500mAh 3S 35C battery

The frame with camera box and all other accessories weighs about 35.7 oz, the camera an additional 8.0 oz, and the battery 14.4 oz, for a total weight of about 58.1 oz, or about 1.65 kg.

We had flown the drone without the camera, and with older and lighter batteries, and it performed well, hovering at less than 50 percent throttle, and was responsive and stable. However, upon adding the new heavier battery and the camera, it became very difficult to get off the ground and control.

The gist of the problem seems to be that the drone is simply too heavy for the motors to carry. More upward thrust is needed. I’m looking for suggestions as to whether it would be better to

A) modify the drone we have, or
B) retire it, and get something larger.

As for option A, it seems we might use larger diameter propellers and/or more powerful motors and ESC’s. But, we are not sure precisely what components to get, or even whether it is a good idea to try to carry so much weight on this frame.

As for option B, the options are limitless. We have considered changing the frame to a F550, or even upgrading to something larger like the DJI S900 or S1000. The larger frames are attractive to me because of the ability to carry more and better equipment, but also comes at a price tag which I’m not excited to pay.

Would appreciate any comments or suggestions on this situation. Thanks in advance.

Al

2

If memory serves me the 450 was spec’ed at 1600grams by DJI. When you model an aircraft with something like eCal.ch that takes into account all the parameters of an aircraft and gives you estimates of flight time, you find there is always a point of no return where additional battery power cannot over come the additional battery weight and you gain small or no flight time for the bigger battery.

The old 450 and 550 frame arms are notorious for flexing. This intern causes vibrations that affect the whole aircraft. So personally would recommend cheaper, better and more fun than you other options.

One option is a H680 Folding frame. I like the basic design because the main box has lots of room for electronics, it folds making it easy to carry, the box frame is stiff and solid yet light. Many people get 30 minutes or more flight times out of their builds. The frame is relatively cheap but there are lots of variations.


https://www.fpvmodel.com/daya-680-new-3k-carbon-frame_g1159.html

and many others. They vary by carbon or fiber glass plates, the type of clamps for the arms, the additional little platforms to mount extra gear and the overall weight. So you need to look at the versions and make a list of features to compare.

I have built a number of different versions and also many Tarot frames and I like the H4 680 better.

Have fun.

3

@BigAl :
Could find much better than dji at a much better price.

Tarot real carbon frame 800 or 900mm will be steady even in strong winds. DJI will be all over the place :slight_smile:
Beside your Samsung cam will need a decent gimbal and associated (preferably) 32 bits controller.
If you don’t know what to do with your money, DJI is perfect!
Spend money with DJI
ecalc is pretty good to evaluate within 10% time weight etc…
Large props 15 to 17 inches give good strong lift even with heavy birds.
5008 pancake motors are economical and very performing…

I build and fly many large camera rigs but never with dji LOL :smile:
Happy building.

Henri

4

The best option with your current setup would be to go to 4S assuming the hardware can handle it. With equivalent weight (smaller capacity 4S) your mid throttle would be a lot closer to 50%. But as Mike says those frames are not good at carrying load, they are too compliant.

1 Like
5

Thanks guys. I appreciate the suggestions. I like the idea of using a larger frame. The 680 is almost exactly 50 percent bigger than the F450, and my sense is that it would be suitable to carry my present camera, and even a bigger camera should I choose to upgrade that in the future. But, I will look at the various suggested frames. Mike, thanks for the particular suggestions (what motors and props do you use with the 680 frames?).

Yes, Henri, I will want to put the camera on a decent gimbal. I mounted it in a box temporarily, but with little shock absorption. It needs improvement. I’m not tied to DJI. I had looked at eCalc, but got a bit overwhelmed with it and wasn’t sure what to enter for various entry fields. I’ll look again.

Al

6

Here is your current setup in eCalc for reference:

F450%20Overload
F450 Overload.JPG1139×754 166 KB

1 Like
7

Thanks, Dave, that’ll help alot as I try to figure out how to use eCalc.

8

I think you will find if you substitute a 4S 4000mah battery (guessing equivalent weight to your 3S 5500mah) mid throttle would be ~55% and flight time would not be reduced by much. I had a 6S battery on a 450 frame with extended arms. It flew just OK but the frame wasn’t really sufficiently rigid. That quad crashed spectacularly and I didn’t rebuild it.

9

I used the quite efficient T-Motor Antigravity 4006-380kv which are a bit pricey. Most motors in that size range would work and you would adjust the kv for the battery voltage you want to use with a rough ballpark of 350kv for 6s, 470jv for 4s and 700kv for 3s. The frame supports 13-15" props.

There are a number of threads on the various version on RCgroups if you want more info.
https://www.rcgroups.com/forums/showthread.php?2163792-Opinions-on-HJ-H4-Reptile-folding-carbon-frame

https://www.rcgroups.com/forums/showthread.php?2730624-Daya-H4-680-Alien-quadcopter-with-Tarot-TL2954-4006-320kv-motors

https://www.rcgroups.com/forums/showthread.php?2283649-H4-680-Alien-frame-featuring-APM-2-6-(Maiden-Autotune)

10

I signed up for a short term 3 mo membership with eCalc xcopter. The interface is a little clunky in my opinion (how do you save a build and prevent loss of work?), and my knowledge of it limited, but I was nevertheless able to model some possible changes to my existing F450. An instructive video produced by eCalc suggests that maximizing prop diameter increases hover efficiency. Obviously, smaller battery would be advantageous as well, at the expense of flight time.

Results below very hard to see, but gist of it is that by increasing prop diameter from 9.4-4.3 to 10-4.5, and reducing battery from 5500 mah to 4500 mah, the thrust to weight ratio increases from about 1.5 to 1.9. Flight time even increases slightly as well.

Big picture, the flight times are still too low. I’m going to experiment to see how using a 4s battery affects the results. Thanks for all the help!

F450%2C%20with%20larger%20props%20and%204500%20battery
F450, with larger props and 4500 battery.jpg1727×895 254 KB

11

In e-calc did you intentionally reduce the frame size to 400mm instead of 450mm? At 450mm the frame should accommodate 12" props which would increase your thrust even more.

12

Build the 680 and use the 450 as a “sport flyer.” Lots of people get caught in the same swamp, including me. I built a 500 class quad and it didn’t take me long to figure out that to carry a camera and a gimbal you need to go bigger. That’s why I built a Tarot 680 Pro Hex.

The hex does very well, but I am limited to using 13" props and 740Kv motors on 4S. I tried going to 6S, but it really didn’t make much of an improvement. The only way to make the hex “better” is to extend the arms so you can run 15" props… Even so, the 680 is speced out for a max AUW or 3.5Kilos, so if your build will be more than that, I highly recommend going with something that has 25mm arms.

With that being said, you might want to look into a Tarot 650 Sport. You can replace the stock arms with arms for a 680 Pro Hex. This will give you enough room to run 16" props. I have one setup this way.

I’m using 5010-350Kv motors on 6S and carrying a 3 axis gimbal with a STorm32 controller and a GoPro Hero 3+ Black. Here are the specs:

AUW (g) 3281
Battery Capacity (mAh) 10000
Number of Cells 6
Battery Weight (g) 1220

Number of Motors 4
Thrust per Motor 820.25
Motor Efficiency (g/W) 7.87

Expected Flight Time 31.9501371533
Flight Time with 20% Reserve 25.5601097226

Aircraft Dry Weight (No Battery) 1734

Tarot 650 Sport Stretched to 662mm
Pixhawk w/GPS
3DR 915mHz Telemetry
XT-Xinte 5010-350Kv Motors
1655 CF Props.
Tarot Retracts
FlyTron Navigation Strobes
Craft&Theory Telemetry
6S +12 volt BEC
6S +5 volt BEC
OLED Display
3 Axis Gimbal w/ STorM32 Controller
GoPro Hero 3+ Black
Tarot “Carbon Look” Canopy

A couple of caveats:

Use a separate +12 volt BEC to power the retracts, the gimbal, and an FPV transmitter(if you use one)…
Use a separate +5 volt BEC to power the Nav Strobes and an OSD (if you use one.)

13

Just click on share and bookmark the build. eCalc stores the url with all the parameters in the url line. Next time click on the bookmark and login to start working again.

My articles on eCalc are a little old but might help.
# A tutorial on using eCalc
# Using eCalc to optimize motor selection.

1 Like