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Sep 11, 2019, 04:56 PM
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Wintr's Avatar
Originally Posted by FR4-Pilot
Are these watt meters bi-directional?
Mine is marked "Source" and "Load" on opposite ends.
Would I just get negative current readings if I hooked "Load" to the battery and "Source" to the actual load?
Or would this let the smoke out ?

I'd like to get a 2nd opinion on the mAh going back into a lipo during charging, but the connectors aren't the right gender if I have to connect Source to charger and Load to battery.
I wouldn't recommend reversing it; depends on the design of the meter in question, but it *could* damage it. Just get two pairs of mating connectors and make adapters to reverse the connections; just be sure to remove them when not doing your special test.
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Sep 12, 2019, 03:32 AM
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icarus the 2nd's Avatar
Originally Posted by Wintr
I wouldn't recommend reversing it; depends on the design of the meter in question, but it *could* damage it. Just get two pairs of mating connectors and make adapters to reverse the connections; just be sure to remove them when not doing your special test.
+1 on that

be careful with a wattmeter, I've seen a few accident already in my club when ppl hook them up the wrong way

I added a a visible 'LIPO' and 'ESC' label to mine so I can't make a mistake

and make sure you have all sorts of connectors or bypasses for all your possible lipo connectors
Sep 12, 2019, 03:05 PM
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Roger that. Glad I asked first

Just found some threads over on HobbySquawk on the Pandora - very interesting. Seems there's a motor that MotionRC carries that's a nice little upgrade for this plane, but it doesn't show up on the website when you go to the motor section. It's there if you follow the link from the thread however (odd). Might keep this one in mind if the Emax conversion doesn't work out well.

The Emax motor is a little noisy for some reason (?) Replaced bearings twice, shaft is straight, even cleaned up excess glue boogers around the magnets that could have been touching the stator. Measured magnets to make sure one wasn't sticking out, measured roundness of the bell (ID and OD), etc. Also tested both bearings in the stator with a separate 5mm shaft (no magnets) to see if they weren't concentric and binding - all good. It's much better than it was before I did any of this. We'll see how it works in action I guess.

Hopefully I'll get to test this out early Saturday morning before the winds arrive ...

************************************************** ********

Tested the setup with a freshly charged 3S 2200mAh.

First run up resulted in 23.57Ap, 258.5Wp and 12.22Vm.

Here's a video of the 3rd run up on that same lipo:

Pandora 1100kV 10x5 40A WattMeter Test (0 min 42 sec)

Looks like there shouldn't be any fire
Last edited by FR4-Pilot; Sep 13, 2019 at 10:58 PM.
Sep 14, 2019, 08:03 AM
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Success! 4 flights this morning with the 1100kV/10x5/40A power system.

A little more power now. Definitely louder. I really like how it flies though
Much better in loops - doesn’t fall over at the top anymore.
I was ready for that tail and had better take-offs today too.

3S 2200mAh Packs are still 3.75 - 3.8v after 5 min flights.

Given the above watt meter readings I'm going to order/try a 10x6 prop next.

Then, going to order/try the FMS 850kV motor with stock 3-blade prop and 40A Hobbywing Platinum ESC ...

Freewing Pandora 3S 1100kV 10x5 40A (6 min 27 sec)
Last edited by FR4-Pilot; Sep 17, 2019 at 09:13 AM.
Sep 14, 2019, 11:49 PM
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Good flying.

My Lanyu 1400mm Super Decathlon sounded just like that for the first 10 or so flights, then I took the OEM ripoff APC Looking prop off and put it on a good balancer (DuBro) the hub was way way way off balance. I probably flew it for 2 flights after adding lots of CA to the hub to balance it, then put a real APC prop on it that was 99.9% balanced from the factory and that noise went away.

You might want to check the prop balance. (BTW - I got rid of the cheap pain to use MAS balancer)
Sep 16, 2019, 09:44 AM
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Thanks! I will double check that prop, along with the spares I have. I'm thinking it's the motor at this point, but I've been wrong before I remember the Sensei making a similar noise when I first installed that motor some years back too - before the crash (?)

I like that this plane doesn't have two issues (IMO) that annoyed me with the Apprentice and Sensei - glued components. On the Apprentice the plastic firewall/motor mount is glued to the front of the foam fuselage. On the Sensei the foam cowl is glued to the front of the foam fuselage. Any type of servicing or repair requires having to deal with (remove) the glue, then re-gluing or coming up with an alternate solution, later. Not the case at all on the Pandora Kudos !
Last edited by FR4-Pilot; Sep 16, 2019 at 03:45 PM.
Sep 16, 2019, 08:34 PM
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Okay, lesson learned.

Absolutely NO (None, Nada, Zilch) axial end play in the motor shaft - if you want it to be quiet.

Last week I put a 0.016" thick shim behind the e-clip, which helped a lot. Evidently it wasn't quite enough. Today I added the 0.009" shim (for a total of 0.025"). It was slightly more difficult to get the e-clip on, but it's on and the noise is 100% gone! Spinning the prop by hand reveals no more grinding-like sound. Spinning up with a battery and yep, only the quiet sounds of an electric motor & prop can be heard.

This was driving me NUTS !!!

I wonder how much power that was robbing (?) It was pretty darn loud in flight.

(I bet I can finally silence that noisy bathroom exhaust fan now ...)
Last edited by FR4-Pilot; Sep 18, 2019 at 11:28 AM.
Sep 16, 2019, 09:52 PM
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hahahahah. When you do, tell the guys from building maintenance about how to fix the replacement fan motor in the BR at my work!

Glad you got it sorted out.
Sep 18, 2019, 07:15 PM
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Alternate Motor #2 Arrives

It's only around 4g heavier than stock.
Stock motor mount fits perfectly.
It's rated at 350W, 50W more than stock.
Needs a 40A or better ESC.
It's got some beefier wires too
Also received the APC 10x6E for the Emax 1100kV ... watt meter time Should have ordered a 9x6 too ...
Last edited by FR4-Pilot; Sep 18, 2019 at 07:20 PM.
Sep 18, 2019, 07:29 PM
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My FMS 980mm P-40 has a very similar motor to that OEM Pandora Motor. It is a 3648 - 770KV and with the 70 Amp ESC it pulls the little P-40 along at about 90-100mph on a 4S 2200. Probably more motor than the Pandora airframe can handle, but I wonder if the OEM motor being an 800kv could run on a 4S?
Sep 19, 2019, 07:54 PM
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Well, I know a few pilots are running 4S with the stock motor, some even with the stock ESC. I don't feel safe about the ESC. The motor, maybe, but there are no Max RPM specs published so I would want to keep the RPMs close to where they are with a 3S so the bell housing doesn't explode. As long as one stays comfortably under 300W and 26A and whatever Max RPM I would think it could work, long term (?) If I'm understanding the motor's specs correctly that is.

So if they did their homework and everything checks out then great! But if not, well, that's another story.

Getting mixed signals about tomorrow's weather forecast ... I'm bringing the plane to work just in case there's an opportunity to test out the quiet Emax during lunch

BTW - It's really good to see those Out-Of-Stock Pandora parts have been replenished at MotionRC
Last edited by FR4-Pilot; Sep 19, 2019 at 08:15 PM.
Sep 19, 2019, 09:00 PM
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I checked yesterday ... still no Red out of stock Pandoras at that time.

Well the P-40 does turn a 10.5 x 7 three blade prop. I hadn't measured the watts, but recall it was supposed to be close to 550, I just got another prop to test it out, but did run a test with a APC 10x10 2 blade and it was a few watts less .... I need that .5" ground clearance, and a broken $3 prop doesn't happen as often as a broken $13 3 blade prop - 16 flights, 3rd prop and I still need to replace/repair the landing gear. There are just some times not to fly - like when the mowing machines are closing in on the runway.

It I get the pandora and upgrade it, I could see putting that 3 blade 4S power system in it. But probably not till I made sure the screws held the wings on well enough with a hundred or so flights all stock.
Sep 20, 2019, 03:16 PM
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It’s HOT today ... but I tested the ‘quiet’ Emax 1100kv with a 10x6E prop. This is going to be fun ! Boy does she move now. It was very difficult to read the watt meter in the blinding sun but I recall seeing around 27A and 300W with a freshly charged pack. More ‘testing’ after work

That tail wheel, however, needs some work - there’s way too much slop between the wheel and its axle. Sometimes it veers left, other times it veers right. All with the rudder centered. No wonder my ground handling isn’t going well ....
Last edited by FR4-Pilot; Sep 20, 2019 at 03:23 PM.
Sep 20, 2019, 04:17 PM
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Sometimes you have to put a tube in the axel hole when it is worn out or too large. I usually use brass or nylon if you can find it. You may have to drill the hole out to fit. My FMS Staggerwing had premature wear on one of the wheels axel hole .... plastic is probably not as good as the DuBro wheel hubs. I used brass tube because the ID fit over the retract axel and the OD fit in the elongated hole, used a little Gorilla Glue to fill in the rest of the space. Works good now. I only have about 30 flights on that plane, and this was at least 10 flights ago.

So that 1100 KV motor woke it up with the right prop.
Sep 20, 2019, 09:38 PM
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That's a great idea with the brass tube. I'll have to take some measurements and see what I can find. Maybe a little heavier tail wheel too - the plane is a bit nose heavy with the Emax. Trims are all out of whack now, but I'll get that sorted. I definitely have to get rid of that slop - Thanks! Need to find a little collar too - the stock solution is a plastic screwed on cap on the end of the shaft (?)

I measured the power again after work - 304W at around 27.4A. Extra drain on the cells during a 5 minute flight leaves them at around 3.75V - not that much lower than the 3.8V from stock. It's just a more enjoyable flight. It's worth it

It's not warbird speed, but it scoots along really nice now. It wants to roll a little more to the left now, at least it did during the last 4 flights. I have some video footage to sort through ... Some guy drove into a mall across from the flying field, so I have a bunch of news helicopters in the on-board footage
Last edited by FR4-Pilot; Sep 20, 2019 at 10:06 PM.

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