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Test of DJI 9443 (NST) plastic props vs. carbon fiber

Discussion in 'General Discussion' started by ElGuano, Mar 30, 2014.

  1. ElGuano

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    Not sure how useful this post will be to anyone with a 1.1.1, as anyone who got an earlier version has burned in effigy and taken out a contract on any retailer that sends old stock. But for some of us with older Phantoms, the non-self-tightening motors mean we can't use the integrated-nut props. Finally, DJI has released a version of their 9" 9443 props for holdouts like us.

    As mentioned earlier, I got several sets of these genuine DJI non-self-tightening plastic 9443 props ("knockoff" versions of this prop have been available since the Vision first shipped). I've been looking for these for a while, but finally jumped on them when I found them for the standard price of $15/pair and genuinely needed "upside down" props for the bottom motors on the Y6. Of course, I couldn't go without testing them on the Phantom.

    Carbon fiber (knockoff) 9443s:
    [​IMG]

    AUW with carbon fiber props: 1282g
    [​IMG]

    DJI NST 9443s:
    [​IMG]

    AUW with DJI NST 9443s:
    [​IMG]

    It's a windy day that I normally wouldn't fly in, but just hovering in the yard fighting the wind is fine. I'm aware that DJI claims the plastic props are better for forward flight because the flex of the material acks as a beneficial mechanical hinge, so I'll need to test constant motion and aggressive flight separately. But for now, it's just hovering.

    Flight 1: DJI NST 9443 (plastic):
    AUW: 1294g
    Battery: Maddog 5400mah 3S2P
    LV settings: 10.60/10.40v
    Flying style - hands off hovering
    Landing: 18:32 at 10.60v. (11.0/11.1v resting/5min voltage)

    Flight 2: knockoff NST 9443s (carbon fiber)
    AUW: 1282g
    Battery: Maddog 5400mah 3S2P
    LV settings: 10.60/10.40v
    Flying style - hands off hovering
    Landing: 18:50 at 10.60v. (11.0/11.1v resting/5min voltage)

    Honestly, within the margin of error. I don't automatically think the knockoff props are better (though they are ~12g lighter, you can decide whether that correlates to an 18-second difference), but I had always wondered the knockoffs were significantly WORSE than the genuine DJI props. It seems like they're not.

    I threw the NST props onto the DuBro to check balance. They were close, but not perfect. Much better than most of the knockoffs I've gotten. I'll probably sand them a bit to get them just right.

    An interesting not, they're also not quite as thin and flexible as the gray E300 self-tightening 9443--those are actually so thin they're translucent!

    But mainly, these are for my Y6. And I love that DJI made them without a top collar to prevent you from accidentally installing them upside down. Because on the Y6 the bottom motors need upside down props. I can just pop these on without modification, and I love that the fit is so snug that I can literally fly the hex without prop nuts installed. The props push up so they won't come off even if the prop nut falls off.

    [​IMG]

    I think these are going to stay on the Y6, and the carbon fiber 9443s are going back on the Phantom, where they've been living for the last few months.
     
  2. davemcm

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    I'd be very interested in the flight characteristics of the cf 9443 on the phantom for forward / aggressive flight.
     
  3. ElGuano

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    All I can offer is the subjective view of someone who flies a lot but not extremely aggressively, except when recovering from wild swings in manual mode.

    The 9443s (genuine or knockoff) are "fine" in forward/aggressive flight. They're responsive and efficient. They're not as "crisp" as the 8045 props, but the 20%+ flight time increase more than makes up for it, especially if you're flying slow/steady for AP/AV.
     
  4. davemcm

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    Manual mode? That's way more than I've ever dared to go lol...

    Thanks for the review, I think I'll need to get myself a set, the only thing I didn't like about the plastic 9443s (original more so than knockoffs) was the durability, they seemed to shatter at the sniff of a twig.

    How do the CFs stack up in this regard? Have you have any mishaps with them? Do they seem as though they would break / chip easily?
     
  5. ElGuano

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    Yeah, I've had big and small crashes with both. I would say two things:

    1. The plastic DJI props are probably a bit more resilient. They're bendy and chip off smaller pieces. The CF props are thinner and stiffer, so they're more likely to chip. I don't go with CF for impact resistance, and would recommend staying with plastic if you're acro flying and crashing a lot :)

    2. Knockoffs are knockoffs. The manufacturing quality varies. DJI's props are very well made and are mostly balanced, and consistent out of the box.

    Don't get me wrong, I like my CF props and will keep buying them for my Phantom. It's just getting harder to recommend them to people with the availability and lack of hassle with the genuine plastic ones. 4 props saves me 10g by going carbon fiber, which for me is a lot.
     
  6. davemcm

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    Ahhh, I would have thought the opposite, however what you say makes sense, they are stiffer.

    Anytime I crash with plastic 9443s a big chunk comes off rending them useless, or they near enough half, completely taking one blade, also rendering them useless. My most recent flights have been back on the original 8 inch blades and I had forgotten how robust they were, mostly just bending or slightly chipping if anything under big and small crashes.
     
  7. davemcm

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    Like these, small crash from 15ft straight down onto grass :eek:

    3/4 unusable
     

    Attached Files:

  8. OI Photography

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    Wow! I guess highland grass is much tougher than Tennessee bluegrass :D Honestly, I've dug enough furrows in my yard and trimmed enough grass with my DJI 9443's that they can probably be classified as gardening equipment now...and I'm still on my first set. Usually it just takes a little warm soapy water after a flight and they're as good as new.
     
  9. ElGuano

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    30ft drop onto concrete at full tilt,2 bounces, landed upside down with motors on for 5 minutes before recovery.

    [​IMG]

    Zero damage to Phantom, gimbal, gopro or fpv...
     
  10. ianwood

    ianwood Taco Wrangler
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    Good job on the testing. I am actually surprised the CF props faired as well as they did considering most find them to be worse than stock P2 ones. I would guess there is a variety of knockoffs with some closer to stock performance than others.
     
  11. ElGuano

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    Most people who get these props don't take the time to balance them well, which they really need. A lot also don't understand the difference between 9" and 8" props which they're replacing. I've bought from a variety of sources and to me they all seem the same (they all come from the same knockoff factory mould). By far, the most reports I've seen are people who get them, try them without balancing or adjusting gains, and immediately write them off saying "carbon fiber sucks!" :roll:

    It's understandable considering how absolutely plug and play the genuine DJI props are, but I have so many different sets of the cf 9443s and have balanced them all, and they all perform brilliantly once that's taken care of.
     
  12. ericdes

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    How have you balanced the props, sanding or tape? I'm assuming sanding isn't so efficient.

    Also, you adjusted your gains. A lot?

    I am in the hunt for some P2 props on my 1.1.1, and am undecided, although CF is lighter, they are not gaining my trust. I never land it, but hand catch it, so landing damage won't occur unless I crash it.

    Thanks for your comments.
     
  13. ElGuano

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    I've done both. Sanding is extremely efficient, and lets you make minute adjustments in weight/balance that you will never get with tape. Tape is pretty convenient and easy to reverse though.

    I've played with gains quite a bit. Mine are definitely adjusted from a Phantom 1, but so is everyone else who has moved from 8045 to 9443s.

    If you don't trust CF (which is fine), the answer is simple: grab a set of plastic 9443s. They have genuine DJI versions of both self-tightening and NST, and there are knockoffs of both of those as well (though if you don't trust knockoff CF, I'm not sure why you would trust knockoff plastic). I hand catch about 50% of the time, but have also never had a tip-over on landing...CF and plastic seem to fare similarly in either case.
     
  14. GearLoose

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    I really appreciate the link you offered in the other prop thread, though it irked me to pay almost $12 shipping on such featherweight items. :twisted:

    I'd previously used a set of xoxo props, which seemed to work just fine until a tree got in the way. Only one prop was damaged but I just didn't have the heart to try flying with 3 of one kind and 1 of another!


     
  15. ianwood

    ianwood Taco Wrangler
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    Very early on, I actually tried a set of CF props and even tried my hand at balancing them as well. They were the same pitch and overall shape as the stock P2 props, probably a simple reverse molding. Who knows if I did it properly but the results were lackluster. The CF props felt really twitchy and descending was noticeably more unstable. I should try them again now that I've got a little more time under my belt but frankly I have no complaints of the stock props.

    My big gripe with the CF props is purely theoretical. I am no aerodynamics expert, but I think one of the important characteristics of the P2 prop is the flex. It's aggressively pitched with a large surface area. I can see how it produces more thrust per in/lb of torque compared to P1 props. But with that comes an increased risk of laminar separation (i.e. stall, cavitation, VRS).

    This is where I would assume the flex comes in to effectively "reattach" the airflow to the "wing" in turbulent conditions. The "wing" flexes under lift and assumes it's more natural shape if lift is lost under isometric or inverted pressure. And in reverting to it's natural shape, it more quickly restores the surface flow and pressure gradient needed to produce lift.

    The CF prop eliminates most of that flex and as result the aggressively pitched prop would in theory be more prone to a loss of thrust in certain conditions given it would take longer to "reattach" the flow. What I would love to see is a CF prop actually designed for the material it is made of and not an "aped" copy of the stock P2 prop.
     
  16. ElGuano

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    DJI makes the same claims as to the flex of the plastic props. The thing is, I think the real-world impacts are far smaller than the theoretical impacts. By far the most loss-of-control-on-descent and VRS cases have involved genuine plastic props, and DJI's firmware update to decrease descent rate is implicitly tied to the effect experienced on their own props and not on knockoffs. And my own tests show the same/greater flight times with the lighter cf props than the genuine plastic ones.

    IMO price, convenience, manual labor and weight are the main considerations; performance differences isn't high on my list.