fozjared

I am using this motor:

http://hobbycity.com/hobbyking/store...28eq:_70-55%29

(the hobby city beast, in case the link doesn't work, here are the specs)

Model: TR80-100-A
Turns: 6
Maximum Power: 7000W
Resistance: 17ohm
Idle Current: 3.5A
ESC: 150A
Input Voltage : max. 48V
Kv : 180 rpm/V
Weight: 1570g
Shaft: 12mm
Voltage Range: 20-48v
Non Load Current: 3.3A
Equivalent: 60-80cc Gas Engine


with the turnigy esc, and a 24x10 wood prop.. i programed my throttle range into the esc as well as programmed it for high timing mode.. it seems to have a ridiculous amount of thrust, so i test flew her yesterday.. she got a long ways down the runway and was still not off, so, stupidly i horsed her into the air with nearly full elevator deflection and then she just barely flew around at stall speeds the whole way around and just sunk back to the ground.. not nearly enough power for my 50cc yak 85" when this motor is capable of putting out way more power! what am i doing wrong? i am running it on four 3 cell lipo packs, 2 pairs in parallel and then each pair in series, thats 22v right? that would be read 12s 2p right? anyway, there has to be something i am doing wrong, this motor should be able to easily tow this plane on 22v right?

exeter_acres

My Feedback: (2)

what is the final mAh that you came to with the packs>?

fozjared

8800mah, does that make a difference in power output, or just length of flight?

exeter_acres

My Feedback: (2)

what are the mAh of each of the individual 3S packs?


and exactly how do you have it wired??
maybe a diagram....


I can only assume that either the volts or amps are too low.

fozjared

each of the 4 packs are 2200 mah.. totaling 8800.. i have 2 of these hooked up to the 4 battery packs:
http://hobbycity.com/hobbycity/store...cks_in_Series_

and those two harnesses are plugged into this harness:
http://hobbycity.com/hobbycity/store...s_in_Parallel_

exeter_acres

My Feedback: (2)

so you are only using 4, 3 cell packs?

fozjared

just plugged all 4 packs up to the 3 harnesses i have set up and tested it with a voltmeter.. got a total of over 24 volts.. so that would be the correct setup that i want i guess.. i wonder if i SHOULD go with 5 packs and somehow wire it to where i add another 11.1 volts.. i have heard other people having this same setup on the 85" aeroworks yak and hovering at half throttle, which makes me wonder if i need to reprogram some setting on the esc?

exeter_acres

My Feedback: (2)

if you are only using 4 packs... might want to check your math..... and set up.

fozjared

what do you mean check my math? i'm getting the goal of 22.2 volts (obviously more than 22 on 4 fully charged packs) i do not know what you mean by check my math.. should i have more packs? should i go for 33.3 volts? and how would i wire that into what i already have?

goirish

I would practice with the flaps at about 3 mistakes high. It will certainly cause a pitch change. Again, I don't think I would deploy the flaps at full throttle. maybe 1/4 throttle. If you have dual rate you may want to tame down the throws for the 1st flight. At high rate it can get pretty twitchy. Sorry put this on the wrong post.

DaveFlynn

Not enough volts.

22v x 180rpm/v x 80% efficiency = 3168rpm

You should be running 10 or 12 cells not 6.

fozjared

dave, decided to follow your advice and go 12s (44v)... all i can say is WOAH!!! this thing scared me when i went full throttle! i hope it'll last long enough for a decent flight.. with 4- 3s packs, 2200mah each.. since i am running all four, that means i am actually operating on only 2200mah time-wise, right? so i shouldn't expect too long of a flight right? maybe 5-7 minutes you think?

exeter_acres

My Feedback: (2)

You will burn out those packs....

I suggest just getting some decent 6S packs at 5000mAh

DaveFlynn

That's the setup I use: 4 2200mAh 3-cell packs is series. Works great. I limit the amps to 24. Static amps would be high without the current limit. For more duration double up and use 8 packs.

http://www.traincircuits.com/PlaneCircuits/CSP.html

fozjared

these are 30-40c packs, but i do not want to puff them, so how can i limit amp draw? and if i do, won't that effect performance a lot or not much?

DaveFlynn

Limiting the amps limits the torque, but having the higher voltage will allow a higher rpm as the prop unloads. I don't trust the C rating on batteries and try to stay below 60% of the rating. The 16C 2200 packs I use work great at 22 amps. Above 22 they heat up. They'll do 30 amps for a few seconds now and then. They give me a good flight time when I prop them to average 8-10 amps in flight. 4-6 amps in level flight, 24 amps climbing or accelerating in a hard turn. The CC HV-30 ESC is nice, set to sensitive it limits at 24-26 amps. For bigger power the HV-45 limits to 40 amps. I have 2 HV-45's and have used them with many different setups and never had any problems. I am yet to loose a battery by anything but impact with the ground.

If weight is not an issue try a 12S2P 4400mAh pack built from 3S1P packs. Lots of wires to plug in, but anyone at the field can charge a 3S pack.

exeter_acres

My Feedback: (2)

You use this on a 17 to 18lb 3D/aerobatic plane?

Using what prop?

DaveFlynn

No 3D, just sport. My biggest single motor plane is a 10lbs P-40 with a 16x10 3-blade prop and a 250Kv motor on 12S1P 2200mAh. 24 amps (1000watts) static thrust is 10lbs.

jasonsrc

im no rc expert, but i know my electronics. if you have 4x 11.1 volt 2200mah batteries, then wiring them 2 in series, 2 in parallel, then you have a 22.2 volt, 4400mah, effectively quadrupaling the wattage, by doubling the volts (2 in series) and doubling the amps (2 more in parallel). nice setup.

Nakajima

Actually, the wattage and amp draw are not determined by the battery capacity (assuming you have a battery large enough to handle the system current draw). Those numbers are determined by the motor and prop size.

Let's say I have an AXI 4120 motor with a 13x8 prop that draws 30 amps on a 5S pack - that would give me about 525 watts. Even if I had 100 5S batteries connected in parallel, my amp draw and watts would be exactly the same - I would just get longer run time.

Dr Kiwi

24x10 prop on 180Kv @ 21v under load...Kv x V = 3780rpm... you might get 80% of that with a 24x10 prop, so actual RPM = 3024rpm... x10/1056 ....pitch speed will be under 30mph... and I imagine your stall speed might be more than that! I think you need something like 10s!

I missed the post where you said you were using 12S... but only 2200mAh... if you are drawing say 100A... that's 45C... too much... and you'll only get just over a minute of flight-time....you REALLY need a Wattmeter so that you can find out your actual amp draw.

David Bathe

Guys, e-newbee here.

Dr Kiwi

David,

Here is a good read! http://www.rcgroups.com/forums/showthread.php?t=739069.... and there are lots of other similar threads with useful advice.

Electric flight is really not that hard... just get a grasp of the basics and ask any questions you wish too... someone far smarter than I am will be able to provide the answer.

Cheers, Phil

David Bathe

Thank you doctor... I've added it my reading list.This like goin' back to school again.Still, I'm committed to make the leap to e-pleasure.To be able fly directly from home, instead of a 1hour drive is simply to good to pass up.Believe me, I'll be a regular visiter to these ethreads, asking the typical newbee questions.