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APC Thin props

Discussion in 'General Talk Forum' started by KX-5, Oct 7, 2009.

  1. KX-5

    KX-5 Member

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    Does anyone have any experience using APCs Thin Composite Propellers vs their SloFly versions? I am setting up a dual motor system and will be using counter rotating props. APC has an 8x6E set for electric only. They are a much stronger and somewhat heavier version than the APC SloFly I'm use too. I'm going to use them on 2217/6 motors. I'm wondering how much the extra weight will affect the motor current draw. Any general thoughts on this? This motor with the 8x6 prop put out about 42oz of thrust. I don't have a watt meter and my current meter only goes to 20amps so my test bench does not help on this. Thanks.
     
    KX-5, Oct 7, 2009
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  2. rjarois

    rjarois Moderator Staff Member

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    KX-5, i use the apc props exclusivity....i always use the thin electric on the faster models. i never noticed the difference in weight, just notice the performance difference...i really only use the slow-fly props on my smaller foamies, and use the thin electric for everything else...hope this helps you. peace, randy.
     
    rjarois, Oct 7, 2009
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  3. iflyos

    iflyos Member

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    I use a variety of different props, and have used the APC-E props allot. You won't see an appreciable difference in current draw due to the weight of the -E props, but you will notice improved performance from them.

    They also withstand higher RPM's without flexing, enabling them to deliver more thrust.

    Tim
    AG4RZ
     
    iflyos, Oct 7, 2009
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  4. KX-5

    KX-5 Member

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    rjarois and iflyos, Thanks for the feedback. That's what I wanted to hear! This is a 1500KV motor so RPM's will be a bit higher.
     
    KX-5, Oct 7, 2009
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  5. 66tbird

    66tbird Moderator Staff Member

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    The SF will give more punch at lower flight speeds along with a lower top speed, where the E will kick in more in the mid range of the speed range. I think there is an rpm limit on a SF around 10k but research to fine out. I do know that putting 300+W on a 10x4.7-SF takes it apart where the E held together.

    I fly a 3D/pattern type foamy and the difference is noticeable. If its windy the E prop is needed to move things upwind with less power than the SF would need.

    If it's dead calm I can't keep it in close without lots of power during high alpha using an E.

    There is a nice in between prop out there. It's the APC clone from hobbyking. A narrow tip and a wide blade near the base. Little heavy but tough as nails, with plenty of low-end punch and good top end speed. Even after a big ole pigeon got in my way the prop was fine.
     
    66tbird, Oct 7, 2009
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  6. janbjorn

    janbjorn Member

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    The SF is designed to give alot of thrust at low RPM with the wide blade, where the E prop works best at higher RPM's. That is why the SF prop almost allways draws more amp than an E prop on the same motor because it gives more thrust.

    Allways consider the safe RMP limit of the APC SF. I had one break du to too high RPM and the thrown blad just barely missed my face :eek:

    The formula for max RPM: (http://www.apcprop.com/v/html/rpm_limits.html)
    For APC Thin Electric and Glow props
    Maximum RPM=190,000/prop diameter (inches)
    (For example, a 10x6 glow engine prop should be limited to 19,000 RPM)

    For APC SF props
    Maximum RPM=65,000/prop diameter (inches)
    (For example, a 10x3.8 SF prop should be limited to 6,500 RPM)
     
    janbjorn, Oct 8, 2009
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  7. 66tbird

    66tbird Moderator Staff Member

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    Thanks for the formula look up :D I've been looking for that, and I even search the site :oops:

    The SF is designed to give alot of thrust at low RPM with the wide blade, where the E prop works best at higher RPM's. That is why the SF prop almost allways draws more amp than an E prop on the same motor because it gives more thrust.

    Had to make note of 'almost' because it really is airspeed dependent. This note is more directed as info for those that may not know. A prop should be chosen primarily for the intended flying airspeed first then sized to match the motors output. Once the sweet spot has been found a step up and down in pitch is nice to have handy for changing conditions.

    I can't even think of the total number of times I've seen people do the most irresponsible things relating to props. Mainly from not realizing how delicate they are, especially in the 10k and up range. Heck, I get nervous around prop saver setups ;)
     
    66tbird, Oct 8, 2009
    #7
  8. KX-5

    KX-5 Member

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    I really agree with the prop saver connection. The band can break at any time. The max RPM formulas should be taped to the work bench. A very important safety factor. Thanks for posting them. I started this thread because I'm doing my first twin motor setup and had questions relating to the props. I definetly will use the thin versions for the 1500KV motors. I'm starting a thread on twin motors and relating issues with this kind of setup. Thanks for all the info. It's been very helpful
     
    KX-5, Oct 8, 2009
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