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Old Mar 10, 2015, 04:21 PM
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Rem Fodder's Avatar
Canada, ON, Port Hope
Joined Apr 2012
1,281 Posts
I have some hard numbers on the WACO, starting with weight. Empty weight without main flight batteries comes in at 12.1 lbs. If I go with the twin 4000 mah packs then the flying weight goes to 14 lbs. Twin 3200's drops the weight to 13.7 lbs.

I did the initial dry runs with two props, an APC 17x8 and a Xoar PJA Sport 17x7. The WATTS UP meter captured the peak amps and also the wattage produced. As to be expected the 17x8 prop produced 1438 watts at 46.3 amps max throttle. The 17x7 prop produced 1305 watts at 43.3 amps.

I am a little bit concerned about the weight, I would have liked to have seen the weight come in well below 13.75 lbs, but if this model flies anything like its foamie sibling then the additional weight should be no problem.

The detail work is almost done now, just doing the dummy engine. should have it all wrapped up in the next day or two.
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Old Mar 10, 2015, 10:26 PM
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Staggerflyer's Avatar
Tama, Iowa USA
Joined Dec 2007
589 Posts
Neil, Those are some excellent numbers. She'll fly very well. Mine came out 12lbs 10oz, all up. She won't even notice the extra weight. It might even land better. My Hawk, the one with the Power 110, weighs 14lbs 4oz, with 5000mah 8cells. At half throttle, both take off in 10ft. Your amperage shows you can easily go another inch diameter and/or 1-2 steps in pitch, but the aircraft doesn't need it. Go for it.
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Old Mar 11, 2015, 07:29 AM
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Rem Fodder's Avatar
Canada, ON, Port Hope
Joined Apr 2012
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Thanks Don. The weight thing surprised me a little bit, I really did feel the project would come in under specified gross weight, but being over by a couple of ounces on a project of this size is no big deal. The thing I didn't take into account was that I had both Rx batteries in the airframe when I weighed it. If I can get away with just one pack, then removing one pack will reduce weight by an additional 3 ozs. Also I weighed the main sub assemblies individually and then added up the total as my digital scale is too small to weigh this model fully assembled, so there could be some error in that process as well.

As far as performance I am quite happy with those numbers too. E-Calc was fairly accurate with the data for the P-110 and props used. Surprisingly, when throttle was at 1/2, the amp draw was down near 12 amps. Unfortunately I did not focus on that reading as I was just concentrating on the full power loads. I will retest again and get some accurate readings through a couple of different throttle settings and also tach the motor and props to see how efficient the motor is running. I think the possibility of utilizing the 3200 mah packs is very good, might save myself some coin by not having to buy any more batteries for it. But then again, who can ever have enough batteries? Its like owning fishing rods, can never have too many......
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Old Mar 11, 2015, 10:57 AM
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DeLaReef123's Avatar
United States, CA, Orange
Joined Mar 2014
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Rem, those numbers look spot on. I would not worry about the extra ounces. The wing loading on this plane is excellent. That prop is huge so you will get plenty of air over the wings which is what you really need.
I am actually surprised how little amps you pulled on a 17X8 prop. I would estimated in the 60-70amp range. Sounds like you have an efficient set up. I would not remove the other RX battery. You would be giving up more than you would gain @ 3oz. Just my two cents.
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Old Mar 11, 2015, 08:55 PM
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Rem Fodder's Avatar
Canada, ON, Port Hope
Joined Apr 2012
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The low amps are because of the higher voltage. As per the wattage formula, Watts = Amp x Voltage. Amps and voltage are directly proportional. I knew the amperage would be lower, but must admit I was surprised to see it below 50 amps. I will do another test with mid throttle settings and measured rpm using an optical tachometer. Maiden will still be weeks away, maybe by the end of April. Will post some finished pics after I do the final set of bench tests.
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Old Mar 11, 2015, 09:50 PM
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United States, CA, Orange
Joined Mar 2014
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Rem that is what makes the conversation from IC to electronic so interesting. With electronic kits we are told what to install and we play around with those specs as a baseline. With gas to electronic we need to figure out our baseline. It's a joy and a challenge at the same time. I know your Waco is gonna give you a smile when its in the air because you made it the best you could....and overpower is always fun. Just wished you lived in Florida. ..you'd be in the air by now damn it! I wanna see this lady fly
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Old Mar 11, 2015, 10:18 PM
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Tama, Iowa USA
Joined Dec 2007
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Rem, you aren't really going to get any true info doing half throttle runs on the ground, other than just for interesting info, since the only real purpose of the ground test is to find max pull so you don't fry everything. Just for fun, you could list your ground pulls, then compare them to the readings in the air, after downloading the logs, if your ESC has that ability. (One of the great things about Castle ESCs.) You will find there is no comparison in the readings, as the prop is unloaded in the air.
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Old Mar 11, 2015, 11:08 PM
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Rem Fodder's Avatar
Canada, ON, Port Hope
Joined Apr 2012
1,281 Posts
Don, you are quite correct. For me it is more of a personal interest than anything else to establish some base lines to compare the flight data to. What do you find in regard to a motor unloading when in the air, I've read where some say 10% less draw than when on the bench?

DeLaReef, that is so true about this project. It's been as much fun researching and figuring things out than actually doing the build. The little Guillow's kit that is next on deck in the build line is every bit as challenging. Going from rubber to electric had me scratching my head big time. Good thing there are more than a few guys on RCG willing to chip in to help out, otherwise I'd have a very sore noggin!
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Old Mar 11, 2015, 11:29 PM
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United States, CA, Orange
Joined Mar 2014
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Sore noggins are smart noggins. We need more smart noggins these days. And yes please send me the link to your Gillows build.
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Old Mar 12, 2015, 08:14 AM
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Rem Fodder's Avatar
Canada, ON, Port Hope
Joined Apr 2012
1,281 Posts
Quote:
Originally Posted by DeLaReef123 View Post
Sore noggins are smart noggins. We need more smart noggins these days. And yes please send me the link to your Gillows build.

Sure thing:

http://www.rcgroups.com/forums/showthread.php?t=2350118
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