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DJI F550 Build

Discussion in 'Multirotor' started by GPS, Apr 14, 2012.

  1. GPS

    GPS Registered

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    I think you guys are entirely missing the point of buying a F550: Heavy lifting.  That's what they say it is for and why I got one.

    The F550 manual claims a maximum takeoff weight of 2400 grams (5.3 pounds) so I have to disagree on the weight being the issue.  The weight certainly can't be helping, but I can tell you that the motors and systems can handle the weight easily.  I think Pelagic Pilot can confirm that as he was there and saw the flight himself.

    Clearly the stock DJI propellers are just unable to accommodate their own published specifications.  The F550 is for AP for crying out loud.  I would not be taking these crashes so lightly if I had a $800, or more, camera hanging on there when these DJI propellers fail.

    UAV Products have posted in another forum that DJI has a "V2" propeller and has been delivering the older ones anyway.  At this point it is moot for me as I will not use DJI propellers any longer.

    The whole point of the exercise is:

    - Carrying a heavy load.  This is why I got a F550 in the first place.
    - Looking to get a 30 minute, or more, flight time.

    I will re-run the tests with the 6400 mAh batteries after I receive the new Graupner propellers.  In the end, if I am going to experience any further in-flight propeller failures I will prefer to have the F550 loaded with batteries and a simple POV camera like a GoPro or ContourHD than a real (i.e. expensive) camera.
  2. Tiger

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    This thread sounds like it's heating up so I was going to bow out, but I just got something from Rick Taylor that I thought was worth posting here.  This happened to be in a PM about something else:

    "So I am a firm believer in these Gemfan props! Today at lunch I crashed pretty good. I landed on my back prop. One of the blades was bent up about close to a 45 degree angle at the hub. So I bent it back down level and continued flying another 8 minutes! I could hardly believe it."

    These are the $2.00 cheapo props that both Rick and I have been flying.  The $2 ones are glass filled ABS.  Here is the link to these on Innov8tive:
    http://www.innov8tivedesigns.com/product_info.php?products_id=987

    They also have carbon filled ones that they say are ten times as rigid for $2.25.  Here is the link to those.
    http://www.innov8tivedesigns.com/product_info.php?cPath=46_132&products_id=981

    When you read about these, notice this statement:

    "Also included with the prop is a set of five 9.5mm OD adapter rings that step down the center hole of the prop to allow it fit on 3mm, 4mm, 5mm, 6mm or 8mm motor shafts. If you have a larger threaded shaft on your prop adapter, the center hole can be reamed out to a larger size as needed."

    The colored props are just awesome to fly with.

    ...Tiger
  3. w00d

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    What is your take off weight ??
  4. GPS

    GPS Registered

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    I don't know what my take off weight is/was w00d.  Before I do the next test I will pass by my friendly local shipping service, they have a great scale there.

    What I do know is the kit is a completely stock DJI F550 - their motors, ESCs, frame and so on.  The manual says the frame is 478 grams.  I've added their Naza a receiver and the batteries (2) which are just 500 grams each.  I would guess it is at about 4.4 pounds.  From the (short) flight experience I feel I can still add weight, maybe yet another pound.  This would make sense since the F550 was intended for AP.
  5. w00d

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    It would just bug or it would BUG me no end not knowing the actual cause and the thread has made me curious ...

    As I said I've gotten curious so I also went looking to outside sources of information and as you must have found people seem to be satisfied with their '[size=1.2em]Graupner[/size]' substitutions. Although that said I tend suspect others (including my own) 'anecdotal' reasons for them breaking so I would also tend to take with the 'ole-proverbial-grain-of-salt'

    Some possibles I did pickup on the forums: over tightening, people not knowing their props are keyed and the ever presence of 'Loctite on plastic' which degrades the same plastic ... FYI:

    PS: You really need some Weight Scales ... It's important in getting to know the 'Power-to-weight ratio' questions

    [hr]
  6. GPS

    GPS Registered

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    I saw similar threads on other forums.  Luckily I have not used Loctite and none of my failures were at the hub indicating over-tightening.  I have kept all the broken propellers in case the manufacturer wants them for warranty purposes.
  7. w00d

    w00d Registered

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    I post that mostly for our Sercher'n Lurkers and it's important to eliminate the obvious 'possibilities' before we go and blame the hard to know or the things maybe outside of our of knowings {LOL} for lack of the words at the moment [​IMG]
  8. GPS

    GPS Registered

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    If I had a camera that could do macro I would post some photos of my broken propellers to share the experience with others.  Several guys have looked at them and they look to me like material failures.  They all have broken at pretty much the same location.  That said, the material choice looks to be inadequate.  If you tap the DJI propellers they sound like glass and they seem very brittle.

    Last night at the indoor-fly-and-drive (the last one of the season) Rick crashed his DJI F450 quad which is outfitted with Gens-Ace propellers and he bent one up about 45 degrees and it didn't break.  He then straightened it by hand and eyeball and went on to fly it the rest of the evening.
    I can guarantee you that you will never get a DJI propeller to bend 45 degrees without breaking, and forget about straightening it and flying again.
  9. w00d

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    Meh, I don't have a camera that does MACRO nor do I have a lens that does either ... But I wouldn't let a little thing like that stop me!

    [​IMG]
  10. GPS

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    The Graupner propellers arrived. They sure look nice, but can they fly without breaking?

    I don't think I will have the DJI F550 back together by this coming weekend, and it looks like rain anyway, but the following weekend should be a go. I will attempt another test flight with the dual 3S 6400 mAh batteries and see what the run times looks like.

    DSCF1209-web.JPG
  11. GPS

    GPS Registered

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    I was checking out one of these propellers last night and they have a very different geometry than all the other propellers I have.  The shape is pretty cool looking.  The package says they are "Glass Fiber Reinforced".  Inside the package they talk about storing them in a cool and damp place because the material needs to retain it's water to assure it's strength.  They also include a formula to use to make sure you don't exceed the propellers tip speed.  Made in Germany.  Sweet.
  12. GPBill

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    Sounds like they're made for the Pacific North West.  ;D
  13. Tiger

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    Sounds to me like they are glass filled nylon.  That stuff gets super brittle if it dries out.  When you injection mold nylon, you come right out of the press and into a bucket of water (really!) to keep it from cracking.  Think I'd much rather have glass filled ABS like the colored props we've been using.

    ...Tiger
  14. GPS

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    LOL.  They are from Germany and their weather is probably worse than ours.

    [quote author=Tiger link=topic=1127.msg8850#msg8850 date=1337800831]
    Sounds to me like they are glass filled nylon.  That stuff gets super brittle if it dries out.  When you injection mold nylon, you come right out of the press and into a bucket of water (really!) to keep it from cracking.  Think I'd much rather have glass filled ABS like the colored props we've been using.

    ...Tiger
    [/quote]

    I'm going to soak mine in Palmolive.  :D
  15. Pelagic Pilot

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    How come no one makes clear lexan props. And light them up with a internal led.
  16. Tiger

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    Glass filled lexan.  That would be the hot setup for quads! 

    Rick and I were talking about putting a 1w white LED under the colored props we're using now.  I think that would show up really well.  Tried it with my LED flashlight and it looked good.

    ...John
  17. GPS

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    I think that would look really good with your green/orange or some white propellers.  There was a thread where a guy put some strobe light like flashing LEDs on his helicopter blades and he was able to make some cool patterns.
  18. GPS

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    I did my first flights with the DJI F550 and the Graupner propellers yesterday.  They work great and are a perfect fit on the DJI motors.  They seem to sound different and it also feels like the acceleration is different in a punch out climb.

    I am going to try my heavy lift test again soon and see if they hold up.
  19. GPS

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    I've run about six flights now with the Graupner propellers and I am getting 18 minutes of flight time whereby I was getting 14-15 minutes with the same batteries and the DJI propellers.  I am very pleased with these propellers.  Highly recommended.
  20. Pelagic Pilot

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    Are they longer? Wider chord? Different pitch or just lighter and easier to spin? That is a huge increase in time.

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