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  1. #1
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    Metal prop versus stock prop stability

    Hey guys,

    I have been running between the stock plastic prop and an octura x442. with the stock prop I have managed a best of 49.7 mph with the batteries centered. In this configuration the boat is very stable, even at WOT with little to no chine or torque roll.

    The last few runs I have switched back to an x442 and its a whole different boat, managing a best of 48.5 mph and lots of instability, chine and torque roll at WOT. The batteries were centered and I made no change to the trim tabs. I am really surprised at how unstable the boat is with the x442. Its a handful to drive and loves hopping out of the water with this prop as well. I didn't think the prop change would make such a huge difference on stability but it seems that way. I am wondering if I should dial some down trim on the starboard side to help counter the roll? Anything else to get it dialed in with the x442?

    Both props were running a neutral strut angle.

    ...At this point besides the looks, the plastic prop has run much more stable, and apparently a little faster, odd?

  2. #2
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    i am very new to the boat as in 3 weeks but i also added the octura x442 prop and my boat also seems more unstable too.but tonite i moved my batteries all the way forward and it helped a lot.seemed to run much smoother across the water.even my buddy said the same thing.

  3. #3
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    Differences between plastic & metal props. Is plastic bends once you put WOT so the speed is limited, metal props. is always straight, so you can get the best speed, as you mentioned about stability, plastic is different in metal right, so you should make an adjustment as well on your components. Like trim tabs, battery location, strut angle etc. etc.
    Sharing is the best thing to do on EARTH legally.

  4. #4
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    thats about what i was thinking myself.i added the second set of trim tabs today and set them at 1 degree.once this rain stops i'll be able to test it since everything except the trim tabs will be the same.

  5. #5
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    When the plastic prop flexes it won't "catch" or "push" as much water.

    This reduced drag would reduce the torque roll, but also reduce the potential to reach higher speeds.

    A metal prop won't flex so you are going to have more consistent drag, or reaction, to the rotation (i.e. torque roll), but there should be more potential to reach max speeds.

    If you can settle the ride, you should get higher top end with a metal prop.

    I too notice a more stable ride with batteries further forward, but, this forces more hull into the water, which increases drag, which will also affect top speed.

    Even though the X442 is almost identical in diameter and pitch to the stock fiber prop, blade shape, surface area, and other design factors can make two similar props behave differently.

    Some have "de-tongued" the prop and claim it helps reduce torque roll, but again, this reduces surface area and likely will affect the ability to get the boat on plane as quickly (hole shot).

    It is a game of checks and balances, and finding the correct balance is the trick.

    hog
    Last edited by hog; 05-07-2013 at 10:02 PM.

  6. #6
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    Good info hog. I think I will de-tongue the prop then. That is really the only thing I haven't tried at this point. I don't mind a slower hole shot since at this point if I go WOT out of the hole it will torque roll anyway so I am normally very smooth on the throttle to get it up to speed.

  7. #7
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    thanks hog for the info again.i bent my octura x442 last night.anyone know where to send it to get it fixed?i bent it back almost like the other side or would it be cheaper to just get a new one and only put it on for speed runs

  8. #8
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    Not sure they would be worth fixing, probably difficult to get everything aligned properly again. I'm not aware of any vendors offering a repair service for props, but I could be wrong.

    Props are not very expensive, unless you are paying to have them balanced and sharpened. It always hurts a bit to lose or damage a prop when you have a couple hours invested in the prep work.

    hog

    Quote Originally Posted by jetnfast View Post
    Good info hog. I think I will de-tongue the prop then. That is really the only thing I haven't tried at this point. I don't mind a slower hole shot since at this point if I go WOT out of the hole it will torque roll anyway so I am normally very smooth on the throttle to get it up to speed.
    I haven't tried de-tonguing a prop yet, but have also been considering giving it a try, or maybe trying an M series prop.

    hog
    Last edited by cooleocool; 05-10-2013 at 01:16 PM. Reason: merge

  9. #9
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    wanna try on mine? thats the part that got bent the outer edge i do believe is the tongue correct?and since i am new and have no idea on how to do it and a wife that already says i spend to much time "tinkering" on those things i just bought it already balanced and sharpened.if you don't mind me asking what is an M series prop?

  10. #10
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    For simplicity the M series is a general purpose prop used on lighter weight hulls and is a detongued X series, and allows a little higher RPM.
    "enjoy your ride"

    Dennis

  11. #11
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    ok cool thanks bud.and if i read correctly alls the detongued causes is a less hole shot.i don't go WOT from stand still anyways.so which part number would be a good fit for the spartan

  12. #12
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    Back from trying my detongued x442....I ran it just now, it was windy out and the water was not that calm, but I turned a 46.5 mph top speed with a MUCH more stable boat, even in the sub optimal conditions. Overall, I think the detongue helped, but it came at a cost since the temps were much higher across the board on the 180 ESC (156F on the caps) and stock motor (115F). Normally I run about 110F on the ESC and 100F on the motor. I am wondering if the detongued prop turns higher RPMs and as a result is increasing the load on the motor and ESC? I ran the batts in the center of the hull. I plan on waiting for some calm conditions and running the same setup again to see if I can break 50 mph and get the temps down. Otherwise I am going back to the stock plastic prop since I consistently saw lower temps with the same performance (best top speed was 49.7 mph).

  13. #13
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    Back from another run, dead calm this time. Not much better on the speed, 47.2 mph and the temps were still high. I have an M445 for a cat I am building so I might try that prop, and I will also order more of the stock plastic ones.

  14. #14
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    Don't know why you are not able to exceed 50 mph with the X442. That prop is so very close in specs to the stock plastic prop and on 6s you should be able to exceed the 50 mph barrier. You may want to move the batteries back from where you have them about 1/2 inch at a time. You will obtain your highest speeds when just about the only thing in the water will be the rudder and prop. Make sure you start with the strut level and adjust from there. Remember to only make one adjustment at a time and record results....

    The M445 will get you close to 60 mph or better as it did for me, (63.9) but the temps will really rise on everything. I would use caution if you put that prop (M445) on a Spartan with stock ESC.
    "enjoy your ride"

    Dennis

  15. #15
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    One more thing I am going to try is to thin the blades on the prop. I think that could also potentially be why my temps are higher across the board with the increased resistance.

    In the meantime, I also ordered an x642 and one of the kintec x442 CNC machined props. I have heard some decent comments about them.

  16. #16
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    I've been wanting to try one of the CNC machined Aluminum props as well, but I read somewhere they are more for nitro setups because they won't handle the RPM's of fast electric. I queried Jan at Kintec about them via e-mail last summer, but he never replied.

    I will be interested to hear how that prop works for you.

    hog

  17. #17
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    I have the same x442 cnc prop sitting on my bench waiting on my boat that will be here tomorrow
    Watch this....

  18. #18
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    There was another brand that would shed blades pretty quick on electric but the ones Jan has work great in clean water. If you want to do wave jumping then I would go with stainless.

  19. #19
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    good to hear jan's props are good in smooth water.

  20. #20
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    Back from more testing, this time with a different x442 prop. On this particular one, I really thinned it out and only slightly detongued the prop. I ran a best of 51.2 mph with the batteries just a little aft (toward the stern) of center. It was on nice calm water as well, which probably helped. There was a slight bit of chine at WOT so I could only hold it for about 5 seconds. Nonetheless, 50 mph has finally be broken with a stock motor and the x442.

  21. #21
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    Good for you.... Keep testing and the speeds will come! And I hate it when the dreaded chine walk appears.... To me it's a like a virus, all is good and then you get it........
    "enjoy your ride"

    Dennis

  22. #22
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    Same battery placement, ideal conditions and I just ran a 52.8 mph on the octura X442. Seems to really like that prop. I cant wait to try the x642!

  23. #23
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    Just remember that the x642 has a little more pitch and will put some additional load on the ESC and motor so watch your temperatures, that is if you are running the stock electronics.

    Have you added capacitors to the ESC?

    Oops, I saw on another post that you have a 180 amp ESC......
    Last edited by orca44; 05-25-2013 at 01:29 PM. Reason: Added content
    "enjoy your ride"

    Dennis

  24. #24
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    I am running a V3 180 ESC with the extra cap bank. Temps are around 130-150 on a normal run with the x442.

  25. #25
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    I ran the x442 cnc prop this evening with conditions being a light wind and a little chop and ran a best speed of 50.4mph with the stock motor and esc. So far so good
    Watch this....

  26. #26
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    You guys, Yipscidleedoo and jetnfast are running 6s correct?
    "enjoy your ride"

    Dennis

  27. #27
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    Yes, I'm running traxxas power cells for now.

    Yesterday was the first time a put a gps onboard.
    Last edited by Double G; 05-28-2013 at 09:09 AM. Reason: merge
    Watch this....

  28. #28
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    Yup, 2 x Gens Ace 5000 3s 120C for 6s in series.

  29. #29
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    Wow, a 120c Gen Ace.... That is a lot of discharge rate!
    "enjoy your ride"

    Dennis

  30. #30
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    but that's a good thing right? when it comes to the boats?

  31. #31
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    This morning at 8am hit 54.4 on stock electronics! Subsequently I suffered an extreme blow-over, but came out unscathed.

    I think that's about all stock has to offer. Time to go bigger...
    Last edited by Double G; 05-28-2013 at 09:09 AM. Reason: merge
    Watch this....

  32. #32
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    That is a good thing but I just have not seen a 120c lipo battery.

    Quote Originally Posted by hopduperevo View Post
    but that's a good thing right? when it comes to the boats?
    Good speed.... You just need to work on trimming things up to keep the nose down a bit at those speeds..

    Quote Originally Posted by Yipscidleedoo View Post
    This morning at 8am hit 54.4 on stock electronics! Subsequently I suffered an extreme blow-over, but came out unscathed.
    Last edited by Double G; 05-28-2013 at 09:10 AM. Reason: merge
    "enjoy your ride"

    Dennis

  33. #33
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    Last edited by Double G; 05-28-2013 at 09:10 AM. Reason: merge
    Watch this....

  34. #34
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    On Saturday I ordered two on the CNC props, a x442 and a x443. The x443 is one mm larger and should give a bit more top end than the x442.

    But only the testing will be the proof.

    I am normally not a big fan of aluminum props on high rpm fast elect boats, I have used them on my nitro powered boats without any issues.

    When I first used (2 years ago) a Octura aluminum x442 on my stock Spartan (mainly because they were out of stock on the copper ones) the lighter weight of the aluminum prop allowed the prop to spin up faster causing some cavitation on starts and coming out of the corners, so just needed to use more throttle control.

    I'm thinking the CNC x443 may not cavitate as much as the CNC x442, only testing will tell.
    "enjoy your ride"

    Dennis

  35. #35
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    that's awesome YIP keep up the great work and your spartan looks BA.please let us know how the x443 works out

  36. #36
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    Back to the cnc x442 this morning with no wind and glassy conditions, a personal best on stock esc and motor. I don't think she has much more in her.

    http://s1357.photobucket.com/user/Co...tml?sort=3&o=1
    Watch this....

  37. #37
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    56.7 mph? That's really good on the stock setup! What ESC / motor temps are you getting?

  38. #38
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    That that run was on the second set of batteries. The first run ended after I came in contact with what I think was a fish. It just tweaked the rudder a little. After resetting the rudder angle and a light sanding if the rudder leading egde I made the top speed. Temps for the first run were motor-110 esc-111 batteries-140. The second run was motor-110 esc-121 batteries-130. I'm running the batteries 1" from the back.
    Watch this....

  39. #39
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    I'm blaming the typos on my phone.
    Watch this....

  40. #40
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    Nice speed run .... That is using the CNC aluminum x442 prop correct?
    "enjoy your ride"

    Dennis

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