900mm popwing prop issue

[cc83]

HI all I searched but didn't exactly find the answer. I am running the stock ARF popwing, in addition to having some CG issues I find that the power is just not there, I was wondering if anyone has tried a 8x6 prop or if this is too much prop for the plane. when I put on my amp meter I'm pulling 140W max and around 13.5 amps, 20A ESC...the motor specs says max continuous power 135apms, max continuous current 12A... am I going to burn out the motor even if I don't go full throttle all the time? I could buy a 7x6 or other prop too, with the stock one it seems a little lethargic. thanks!

[soarrich]

The black prop that comes with the combo seemed to work OK, its a 7x5 I think. The 7x6 might let the magic smoke out. I built 4 of these for my friend and me two ARF versions, two bare wings, the bare ones have more powerful motors in them and fly better. I have a 2409cdrom motor with a ACP7x5 electric prop, it has about 50% more go.

A 2200 mah battery will make it balance perfectly.

[soarrich]

I just got back from flying my Popwing, my friend was running a APC 7x5 on his ARF motor, I was running the stock black ARF prop on mine, his seemed much faster. You may want to try the ACP prop.

[JetPlaneFlyer]

You haven't got the prop fitted backward by any chance?.. Wouldn't be the first time

[cc83]

nope not backwards, i'm going to try it again tomorrow and see how it goes, might try the bigger prop but not go full throttle all the time, i'll let you know if my popwing has a unintended smoke generator

[cc83]

well no smoke from the 8x6, flew pretty well too, I did a few full throttle passes but also some slower flight, at the end of the flight, pack barely warm, esc faintly warm, motor cold. So I guess i'll buy a 7x6 and try it, but this seem pretty good so far.

[JetPlaneFlyer]

Seems odd that others get decent performance with the stock set up but you need a bigger prop. The first thing that springs to mind is a poorly performing battery... is the battery old?

[cc83]

Originally Posted by JetPlaneFlyer

Seems odd that others get decent performance with the stock set up but you need a bigger prop. The first thing that springs to mind is a poorly performing battery... is the battery old?

the battery is in good condition, I baby my batteries and I still get great performance with the same batteries on more demanding planes.

I changed out the propsaver for a collet (since there was vibration) and the stock prop, still no power, The prop looks like the pitch is lower than it should be when I measure it, almost 7x4 actually. I didn't have a 7x6 apc or other available at the time, so I tried the 8x6, tried it with a 7x6 apc briefly this morning and it flies well. a little less zip than the 8x6 but I'm not someone who goes for speed anyway and rarely go full throttle.

[JetPlaneFlyer]

To get an idea of what's really going on the only way is to put a wattmeter on it and see what the numbers tell you. You will be able to see how well the battery is really performing by the voltage it holds under load.

[cc83]

Originally Posted by JetPlaneFlyer

To get an idea of what's really going on the only way is to put a wattmeter on it and see what the numbers tell you. You will be able to see how well the battery is really performing by the voltage it holds under load.

I mentioned the numbers in my first post, I think I said amp meter but I meant watt/amp, voltage under load is fine (measured both statically and with telemetry) with both props, after 10 minutes of mixed flight still lots left in the pack and no noticable drop in performance. So i'm pretty happy with it now.

[bluecnc]

Hello all,
Just wanted to chime in. My Popwing is my favorite plane in the hanger. I found the stock power plant a little lacking so I replaced it with a 30 amp Detrum ESC, 1100kv Detrum motor turning a APC 8X6 prop. Flies really nice at WOT for 11 minutes with a 2200mAh battery. I fly at two soccer fields that are end to end and run out of real estate pretty quick. My Tmotor and ESC are residing in a $tree 30 inch wing right now waiting to be maidened tomorrow. Wings are so simple and so much fun. See you at the field.

[JetPlaneFlyer]

Originally Posted by cc83

I mentioned the numbers in my first post, I think I said amp meter but I meant watt/amp, voltage under load is fine (measured both statically and with telemetry) with both props, after 10 minutes of mixed flight still lots left in the pack and no noticable drop in performance. So i'm pretty happy with it now.

Sorry, i missed the numbers in your first post.

If those numbers are recorded with a freshly charged battery then it confirms my suspicions. Sorry to say but your battery is toast. 140W @ 13.5A means battery load voltage is 10.37V. For a 3s pack that is 3.46V per cell. That's REALLY low.
ESC's often trip on low voltage at 3.3V so you are almost low enough to trip LVC even with a freshly charged battery Saggy load voltage is a sure sign of a battery that's past its best.
A good battery will hold 3.8V or more under load when it's fully charged. Putting in a good battery would boost power by around 30% which should take you up around 180W. You will also get much longer flight times before LVC activates.

Time for new batteries

[cc83]

Originally Posted by JetPlaneFlyer

Sorry, i missed the numbers in your first post.

If those numbers are recorded with a freshly charged battery then it confirms my suspicions. Sorry to say but your battery is toast. 140W @ 13.5A means battery load voltage is 10.37V. For a 3s pack that is 3.46V per cell. That's REALLY low.
ESC's often trip on low voltage at 3.3V so you are almost low enough to trip LVC even with a freshly charged battery Saggy load voltage is a sure sign of a battery that's past its best.
A good battery will hold 3.8V or more under load when it's fully charged. Putting in a good battery would boost power by around 30% which should take you up around 180W. You will also get much longer flight times before LVC activates.

Time for new batteries

my bad too, those numbers were not with a fully charged battery, actually they were with one i had laying around at storage voltage, 3.7 per cell...and a 15c one at that, I'm running 20-30c ones. I'll have to throw a fresh one on there and see what happens. I was so excited to get the thing going I didn't slow down to think about it.

[JetPlaneFlyer]

Ahhh.. yes, if the figures were for a discharged battery then you can ignore everything that I said