cbarrett1981

My Feedback: (11)

So I think I bought the wrong electric motor. I put a tgy easymatch .60 300kv on my twist .40. Tried all sorts of props, best is 12x8 APC. I get 6810 rpm with. Well flies good but no vertical to talk about, I love hovering my twist but hated the nitro so I went electric. No hovering now. I am running it with the TGY 85a esc, 6s 3000mah Zippy pack. I fly electric helis so this stuff works and is reliable. Anyhow there is a 400kv and a 500kv .60 motor too. Did I buy the wrong motor?? Also now I am so disappointed that I think I am going to buy a rimfire .55 or .60, not sure what the better would be but I like to overpower for 3d. Any advice would be great. Thanks in advance guys. Also if any knows about these HK motors please help with picking.
Thanks,
Chris

Jet_Plane

You have a VERY low kv motor there.. That means to get decent performance you are going to have to swing a very large prop. I'm thinking probably around a 16x9" prop. You should check the amp draw with a wattmeter, my guess is right now that little 12x8 wont even be pulling 20 Amps. The motor is rated for 60A so to get full performance from the motor you need a prop that will load it up topull close to the motors maximum current.

Problem will be that you may not have enough ground clearance to swing the size of prop you need for the motor, ifsothe 500kv motorwould have been a better match for your plane.

Steve

cbarrett1981

My Feedback: (11)

Steve,
Thanks so much for the answer. I honestly wasn't paying attention when I bought the motor, they are all the same price. As far a 16x9, no way I can swing it. A 14" prop is pushing it. I guess I will order the 500kv motor, any suggestion on the prop?
Thanks again,
Chris

Jet_Plane

Your 12" prop should work ok with the 500kv motor. If you went with the 400kv version a 14" prop would about right.

If you are ordereing another motor then i'd recommend getting a wattmeter while your at it.. That way you can check that you are getting near the maximum from your motor, and more importantly not exceeding the maximum. Something like this one: http://www.hobbyking.com/hobbyking/s...Analyzer_.html

blvdbuzzard

I was curious about this. I used [link=http://www.s4a.ch/eflight/motorcalc_e.htm]THIS[/link] calc program.

I selected the Turnigy G60 (400) motor, 3300 6s pack, 60 amp ESC.

I started with a 12X8, 22 amps and 77 ounces of thrust.

Then I picked the prop I use on a Monster power 60. 16X8, 48 amps and 138 ounces of thrust. When I went to an 18X8, I past the 60 amp limit. It says it will pull 61 amps and have 165 ounces (10 pounds) of thrust.

If I use a 12s setup and a 12X6 prop, it says it will have 54 amps and 198 ounces of thrust.

I would say you have the right motor, just not the right prop for it. You could use a "Y" connector and use (2) of your 3s packs for a 12s setup, weight might be to much though.

I have a Monster Power 46 in my Giles 202. It yanks the crap out of it. I am using a 5s pack, 13X6 prop. Use the calc program to see what different batteries and props do to the setup.

Buzz.

Jet_Plane

blvdbuzzard,
The Tuurnigy G60 motors are rates for a max of 7 cells , so wiring them up to 12 cells would spell almost certain disaster, and i doubt the ESC would take it either unless it's a special HV type. Also the OP's motor is the 300kv version, not the 400kv. The program is very usefull, thanks for providing the link. Using this program it looks like you would have to go up a size on props compared to my initial guess.

cbarrett1981,
According to that program using the 300kv motor that you have right now you would need an 18"prop to max out the motor on 6 cells, which is impractical due to ground clearance.

With the 500kv motor the program is saying a 13" prop would be about right, so this looks to be the one.

I strongly recommend you use a wattmeter to check actual amp draw, you don't want to burn your new motor.

blvdbuzzard

Jet, for some reason I read it that he had the 400kv motor. That does change it by a little

Running it on 12s might just let the magic smoke out of it.

The calc program does help. I have found it to be right at 10% of the values I get with a watt meter on my planes.

I do agree you need, must have a watt meter to make sure you don't smoke test them.

They do not cost much either.

http://www.hobbypartz.com/aeo-p0-watt-meter.html

Buzz.

Jet_Plane

blvdbuzzard,

Yep that online calculator is good. compared to Motocalcthe motor database it has is veryup to date and wide ranging. However I'm sure that the authers of the oprogram are using manufacturers data rather than actual testing to calculate motor performance. This is fine as long as the manufacturers data is accurate.I did a couple of calcs and for my latestHacker motor (A30-14L V2)the prediction of the calculator was spot on, to the Amp. However i then checked with figures i got from an E-max motor (GT2820/07)and the numbers were out by a wide margin (49 amps predicted, 40 recorded in practice). The problemI think is some manufacturers arent very good at giving accurate data for their motors.

It's still a good tool, but it just underlines the need to do a wattmeter check to verify.

Steve

Flypaper 2

Hi guys. Just to add. I have the Twist 40 with a Himax H50 on it 530 KV swinging a 13-6 APC GAS prop on a 6 cell 5000ma Rhino. Goes out of sight vertical in a short time The APC electric prop was showing stress marks at the root of the blades from doing violent aerobatics. Was getting ready to shed a blade. I found no difference in performance between the two with the thicker bladeson the gas prop. A buddy has the Twist 150 with a much larger motor, a Turnigy 63-64 I think, and it did throw a blade. Tore the firewall off the nose and took the batts and all, out of the front of the plane. Got tail heavy real quick. Hope this helps a bit.

edfman

Could you use a 3 blade prop if you're having clearance issues?

cbarrett1981

My Feedback: (11)

So here is my update, Iput a14x9 3 blade master airscrew, crazy vertical, 1/3 throttle hovers, pullouts are ballistic, speed is ok, but this is a 3d monster, thanks for all the hep guys.
Also I get 9 minutes of full throttle flight 13 mixed. That prop woke my motor up. Thanks again.