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FTFC'18 WWII Vought XF5U "Flying Flapjack" designed by SP0NZ & LocalFiend


I like 3D printers...
link for everybody else who was unaware that there was a 3d printed version in the works.

holy heck, are those sunny sky x3520s in that thing? of coure ive got to brag about 600 watts while your nonchalantly sitting on 3000.

26 lbs of thrust must be insane, did the build end up being the full ten pounds like you were expecting?
Actually, I stuck on some SK3 5055 430kv motors. :D The sunnysky's would not have balanced with the two 4500 mah 4s batteries I had. Too small lol.

It was probably very close to my calculated weight. More than half of it was electronics.

Way more thrust than required of course. However, I wanted to run scale sized props.
Okkeedokkeee... so i may have taken a bit of liberty when it comes to the power-plants, but was hoping to test fly this monster this afternoon before finishing it up.

Seriously, if this model isn't picked up for the master series, its a travesty, this is an absolutely beautiful model, based on a one of a kind aircraft, that went together perfectly. Localfiend you should be very proud, this is a work of art, thank you so very much.

Ive got two Turnigy D3530\14 1100kv rated to 315 watts apiece, meaning this should be almost 7/8 horsepower... making this the most powerful one built yet(unless somebody's got one that they've just not been sharing with us) I have a couple 1500mah 3s batteries, and seeing as how the battery is right over the CG, a few heavy 3s 5000mah batteries that should give me flight times of 30 mins at 50% throttle. i gave it a quick punch of throttle last night, and at about 75% it"ll climb vertical, at 100% i had trouble holding onto it... I gots me a jen-you-wine space shuttle :)

AS my motors are wider than the motor tubes, i decided to just print the entire motor pod. printed out in PETG, 3 walls 50% infill... and im not too terribly sure this is a good idea. i need to build a ruler one and compare them. its certainly stronger, i would snap a wooden one with the bending force ive put into it, but they've got some twisty flex to them that might need to get designed out. Ill put up the files, but i wanted to cover it with foam, take some measurements, and make a skinned version with some internal improvements before i put it up on the online.

CG is exactly 1/2 inch behind where it should be without a battery, i think i can change the mount a bit to get it to where it is supposed to... how exact of a science is figuring out the CG?, will that be too tail heavy? surly not right? i still need to weigh it fully assembled, not sure what takeoff weight is with the different battery configurations.

i also need to get a amp meter on it, my multi-meter was in my work bags, so ill make sure I'm not pushing the motors too hard with the four props, but all and all everything accounted for, i should be putting a 7/8th horsepower plane up, depending on whether i can hit that with this prop combo...everybody was saying how this model could use some weight, i thought it a waste to not make as much of that extra weight motor :)

i beveled all the control surfaces, and still need to put on the outer skin panel and final edge piece, and the motor pods.
Ive also have a fpv camera setup i want to put in the nosecone/ cockpit, but dont wanna try my luck just yet. ill get it in the air, then worry about the extras.
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Just curious, what props do you have on those motors?
I ask for two reasons, one because it looks like two regular props on each motor. Does that work?
The other reason is because I have the same exact motor scheduled to go on a future build of mine. I was planning on using a 9"x4.7 three blade prop on a 3S battery. I was going to try it out with a Watt meter hooked up first to see what the numbers looked like, but it seems it should be in the ballpark.
it is just two blades... its kinda a no no, but its about as safe as the friction collet its all attached to. KV on my motors are lowish, and there doesnt seem to be any adverse vibrations, but i don't really recommend it. the motors have screw holes in the top of the domes, i was planning on 3d printing out a spinner to hold them in place, but they fit pretty well as is, and that's just more weight to spin, non thrust weight at that.

power is one thing i had a question about, if i hook up a fluke amp hoop, do i just do it around one of the leads of the battery, and divide in half for each motor? if so, i'm only pulling 6 amps apiece at full throttle, way less than i thought i would be, but the motors are warm to the touch after a good 60 second full throttle punch, just like hothands hand warmer warm. the only thing i can find on the motor is secondhand info, but apparently people have fit up to a 13x6 prop on here with no problems. the wider voltage range is where itll get you, i probably wouldnt be able to run a 13x6 on 4s, but id be comfortable with 2s as long as the amps came out right on the bench before i flew. your 9x47 tri blade should be fine provided you make sure your arent over amping.

had soldering issues and had to hack it open last night to fix, should have it back up again tomorrow
I'm not sure if a loop type ammeter would work accurately on these sort of devices. For one, the voltage going through the motor leads isn't a true AC signal, it's more of a pulsing DC signal as far as I am aware. Also I don't know if the variable frequency would have any affect on what the meter reads. I'm by no means an electrical expert, I'm just speculating here and giving reason why you were getting such low readings. Those little watt meters that hook up between your battery and ESC are pretty cheap and super handy, well worth the investment in my opinion.
After rereading you post, you definitely can't put the loop around the battery lead as the current flowing through that is DC. The hoop type ammeters are only good for AC current measurements. I'm still weary of trying it around one of the motor leads, but I'm curious to know if that would work or not.