motor and prop selection

S

skeeter

Active Member
Hey all, I'm new here and I see this subject has been addressed a bit. I'm not digesting the info I'm getting, so, here goes. I'm not going to list all the various components and brands I have gathered so far but I will give some info that is key in the matter I'm having trouble with. This is a 450mm Alien Spider frame with 30A ESC's (should be enough to handle any motors I need) My AUW is between 1500 and 1600 grams with my motors (assume my motors total weight is about 400g and prop weight totals about 45g using 9045s and 1045s). So I figure from what I've learned thus far the amount of thrust needed to hover will be about 3000g. I'm thinking that amount of thrust should be generated around 50% throttle. If this is the case then the four motors should generate about 750g thrust each. Hoping I'm on the right track I then am having trouble finding a good motor/prop combo that will allow me to have some flying fun that isn't too acrobatic with a certain size prop and allow me to do some exploratory FPV flying in the iron ore hills, cliffs, and edges of forested areas in my locale (Northern MN in case anyone is curious). So, am I on the right track with the 50% throttle? Also, what motor/prop combos will work best for my applications? I will try to answer any questions about my build and appreciate any input on the motor/prop combo.
Skeeter
 
You're correct, you want hover at 50% throttle. To test different motor/prop/battery combos, ecalc.com is an invaluable tool
 
RENOV8R said:
Check out ecalc, it's an invaluable tool to test motor/prop/battery combos
http://www.ecalc.ch/
Click to expand...
I checked it ecalc out , wow! that's a powerful bunch of mathematics! I think I've got it figured out for the most part, glad I didn't try to do the figuring myself, been about 27 years since I've done calculus, lol, not that I really understood what I was doing back then, so here is a question which has an opinion based answer which brand of motors has the best reputation? I like the cobra, but I've narrowed it down to about a million brands lol, Blackwidow, Cheetah, Cobra, Emax, Black Magic, Dualsky, Hitec, Hyperion, and Scorpion. Any and all input from anyone would be greatly appreciated, thanks in advance
Skeeter
 
ringolong said:
T-motor would be my choice for a 450mm.

http://www.rctigermotor.com/html/2014/Navigator_0808/227.html

http://www.rctigermotor.com/html/2013/Professional_0912/44.html
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I like the look and the quality seems very good, only thing is I'm planning on running 4s 35c 6200mah, too much juice for those two motors, I also have a couple 3s 35c 5500mah that I'm hoping to be able to use with same motors, any advice on batts is welcomed, I'll check out some Tigermotors other models, plug em in to the ecalc and adjust the weight, in the mean time please keep the suggestions coming, I'm having a blast learning and assembling the components as I'm waiting for my last ones to come in (easycap and my diversity receiver fpv cam combo) as I'm assembling I'll share pics and progress to another thread
 
OK, I'm still struggling, both my 3s and 4s batteries are heavy but I still want to use them, my total weight without motors is is around 1350g with the heavier of the 2, can any one tell me which motors will work to hover at around 50% and still have some good speed to it?
Skeeter
 
Awesome video, what was AUW and what size prop? And we're you giving it a lot of juice (throttle)? I'm not planning aerial photography/video right away I'm more interested in exploration and a little bit of ripping around (not any major acrobatics)

Skeeter
 
Thanks!

10x5 Graupner props. I would have to add it all up, but I think it was about 1500 grams. It was heavy since it was fully loaded.

It was fast when I was using a naze32, and a little slower when I moved to a naza.

t-motors are very good quality motors.
 
I like what I see in the advertisements for those Tigermotors, spendy but I love this hobby and, well, big boy hobbies cost big boy money, lol, also well built and long lasting, Graupner props have great reviews too, very reputable name, I have an APM 2.8 fc, ublox neo 6m gps, osd, radiolink AT9 Tx/Rx (9 channels in the air, I noticed some of the packages for the AT9 only had 8 channels in the air), additionally I've got the Quanum diversity receiver (5.8ghz) for my FPV, that comes with a 2.8mm 600TVL camera, clover leaf circular polarized antenna in the air, dipole and circular clover leaf on the ground, and lastly an easycap set up so I can use my laptop for a monitor, so since I have some great experience giving me advice, what do you guys/gals think about the whole set up? Specifically the APM2.8? also I'm reading about people getting down on folks who don't use two FPV viewing systems (2 monitors or 1 monitor and goggles) Opinions? Comments? Advice?

Skeeter
 
I use a monitor and goggles, as the goggles don't have video out. So the monitor (Aomway with built in diversity receiver and same antenna setup you have, with DVR) is used for recording FPV video.
 
well I've had my fill of the RTF set ups, they're fun but limited in range, speed, and capabilities, I'm probably just going to use the laptop to begin with but I'm sure I'll invest in good goggles eventually, any experience with APM flight controllers?
 
OK, I'm more confused than ever, I like the T-motors suggested but I don't think they will produce the thrust I need at 50%, maybe I'm not using ecalc right, I have 10 x 4.5 and 9 x 4.5 props I can use right now, no problem getting different props if necessary, id like to be able to cruise at about 35mph my weight without motors is 1368g with my 4s battery and 1140g with my 3s battery, will those motors give me the kind of cruising speed I want? sorry if I'm being cautious, I have no problem spending the money but its still a dent in the wallet, I just want to be sure

Skeeter
 
Did you check the speed with the 10x5 props?

SunnySky motors are good too, and will save you some cash if you are on a budget.
 
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I was looking g at the rpm in the charts, could I run mn3110 780kv with my set up using various props (9045, 1045, and an 11 inch of similar pitch)?
 
I don't think 780kv will give you the trust you are looking for with the prop size that will fit on a 450mm. I think you are going to want 900kv - 1100kv for the type of performance you are looking for on a 450mm.
 
Ok, so I've decided to go with the Tigermotors MT2216 V2.0 900kv, excellent quality, great reviews, and according to others with more experience than me in this matter, with an AUW 0f 1655, they should rip pretty good, now for my next issue, lol, sorry for being a "help me" kinda fella, but, I obviously don't know how to work ecalc, my current drain on the controller and resistance on the battery is a guesstimate, but for all my reading and YouTube viewing I think I'm close, also the selection of the prop is correct as far as length and pitch but my props are some kind of generic brand made of nylon, the GemFan
looks very close in appearance so I just went with it, I don't know the gear ratio for the props so I just let that roll too, hopefully my screen shot is viewable, can anyone tell me what I'm doing wrong with ecalc???
ecalc.png

Skeeter
 
In the battery section, change C Max to 70. Click on calculate in the bottom-right corner and you should be in business
 
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