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Help please, this doesn't make sense

Old 09-09-2009, 02:29 AM
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raflyer
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Default Help please, this doesn't make sense

I have a twin pusher prop Concorde from Dynamic Foamy. 18.5oz 70" long 30"w/s 2 1400kv out runners and a 1200Mah 11.1V 10C lipo GWS 6050 props, watt meter shows this on a fresh charge,
15.6A
173.6W
10.97V
After 20 secs of WOT i get a steady
136W
Correct me if im wrong but at 18ounces and that wattage, shouldn"t this be a fast plane?? It is barely staying in the air! Is it the cheap props?? Thanks for any input
For reference, it is about half as fast as my stock Parkzone T-28

Last edited by raflyer; 09-09-2009 at 03:14 AM.
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Old 09-09-2009, 02:58 AM
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gramps2361
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That should be moving right along with a 136 watts bet ya its the props that aren't giveing you enough thrust. What is the max amps that the esc is rated for? Maybe a 7x4 prop would do the trick you just don't want to many amps if the esc isn't rated for it. By the way not a good idea to run the motor wot for 2 min. quick burst of the throttle to get a reading you can damage the motor doing what you did. So find out what the esc is rated for in amps. the motor also has a rateing for max amps also.
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Old 09-09-2009, 03:09 AM
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firemanbill
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Make sure your prop is on the right way also. numbers facing forward for GWS props. GWS' small props are not bad. I run the 6030's on my Micro SSX and they work very well, and are cheap!
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Old 09-09-2009, 03:10 AM
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raflyer
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I have 2 esc's that are rated at 10amps each. I meant to say 20secs, sorry about that I know i need a higher C rated batt and i also agree that i think the props are flexing to much. I was thinking either a 6x4 or 7x5 APC pusher props. Much stiffer but also heavier. I barely got this thing up to about 150-200' high! Took several anxious seconds to get there and i had trees looming at all around. I was also thinking of different motors but then you get into more weight and all new components.
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Old 09-09-2009, 03:13 AM
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Originally Posted by firemanbill View Post
Make sure your prop is on the right way also. numbers facing forward for GWS props. GWS' small props are not bad. I run the 6030's on my Micro SSX and they work very well, and are cheap!
When you say facing forward, do you mean towards the back of the plane or front of the plane. I have the numbers facing the back of the plane which i believe is correct? It feels pretty strong so i just dont get it. For reference, its about half the speed of my stock T28 from parkzone
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Old 09-09-2009, 03:15 AM
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firemanbill
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Originally Posted by raflyer View Post
When you say facing forward, do you mean towards the back of the plane or front of the plane. I have the numbers facing the back of the plane which i believe is correct? It feels pretty strong so i just dont get it. For reference, its about half the speed of my stock T28 from parkzone
nope, you have it backwards. turn it around where the numbers can't see the plane.

You'll triple your thrust that way.
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Old 09-09-2009, 03:18 AM
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gramps2361
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Lol did that once put a sf prop on backwards set the plane down go to take off my head is turning the way the plane should of gone but she went backwards instead. should of seen the look on my face.

Good point Bill never thought of that with the small prop easy to do.
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Old 09-09-2009, 03:19 AM
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raflyer
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Originally Posted by firemanbill View Post
nope, you have it backwards. turn it around where the numbers can't see the plane.

You'll triple your thrust that way.
I think i told you in a bad way, the motors are in the rear of the plane and they face away with the prop numbers facing towards the rudder. Mounted like this they cant 'see' the plane. Make sense or am i confusing you and myself
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Old 09-09-2009, 03:22 AM
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Originally Posted by raflyer View Post
I think i told you in a bad way, the motors are in the rear of the plane and they face away with the prop numbers facing towards the rudder. Mounted like this they cant 'see' the plane. Make sense or am i confusing you and myself
doh, I missed the pusher part. The numbers should be facing the direction of travel... how's that? Maybe go up a bit on prop size then. My micro ssx is only 6 ounces but only has one motor/prop and a 2s it has unlimited vertical on that 6030. two of them ought to push your along very well.
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Old 09-09-2009, 03:24 AM
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I will say that is definately one of the neatest looking planes in the air that i have ever had. Once i get some more speed in her it should be a blast. Super easy to land.
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Old 09-09-2009, 03:27 AM
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Originally Posted by firemanbill View Post
doh, I missed the pusher part. The numbers should be facing the direction of travel... how's that? Maybe go up a bit on prop size then. My micro ssx is only 6 ounces but only has one motor/prop and a 2s it has unlimited vertical on that 6030. two of them ought to push your along very well.
Ok so numbers should be facing the front of the plane which would have them facing the direction of travel. I will turn them around and try it again tomorrow. Thanks for the help. I am new to gws props so i feel better knowing they work for you
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Old 09-09-2009, 03:35 AM
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I think you will find that will make a big difference!
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Old 09-09-2009, 05:53 AM
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yes, firemanbill's correct, numbers should face the direction of forward motion....

SK
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Old 09-09-2009, 06:00 AM
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Raflyer is going to Say, its to fast Now after Turning the props around LOL, Take care, Chellie
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Old 09-10-2009, 05:00 PM
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Well i turned the props around, wattmeter showed the same as before but it felt a little better. Topped off the 1250Mah 12C 11.1V battery. Launch was a littler better, actually could throttle back to 3/4 for the 1st couple of mins then it was full throttle after that. Barely any faster with the props turned around but it did help. I'm only getting about 5mins of run time. I still feel the props are flexing to much, you can see them move about 3/8" on the ground when you to full throttle. Going to try some 6x4 APC E pushers and see how it does. Hate to spend 120.00 on a pair of Hoffman magnetics motors that are the same size physically except 1850KV:
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Old 09-10-2009, 05:38 PM
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Check your amp usage against the C of your battery. If the C is two low you will limit the power output of the motor and potentially puff the battery pack. I have been using the 25 - 35 C Flightmax batteries from Hobby City with good luck and they are cheap. I changed batteries on my skeeter 36 and it flys like a new plane.
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Old 09-10-2009, 06:48 PM
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I had to change to a stiffer prop on a twin I was getting prop flutter and looseing the thrurst with the prop recomeneded. Swap to a 7x4 aps made a difference.

Darylm you might be right about the amp draw need to find the formula to figure it out the 10c battery might not be putting out enough c's to power the motors properly. isn't it 1.2x10= 12c if this is correct then you will puff the batteries.
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Old 09-10-2009, 08:29 PM
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Originally Posted by raflyer View Post

15.6A
173.6W
10.97V
After 20 secs of WOT i get a steady
136W

Does it output 10.97 or so after 20 seconds... it should stay somewere close to that...

The high initial watts, and drop seem to me that it may be an overprop issue... try apc 5x5e prop... or 6x4e...

If I know exactly what motor your using, I may be able to give you a better idea of prop selection...

SK
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Old 09-10-2009, 08:32 PM
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Originally Posted by gramps2161 View Post
I had to change to a stiffer prop on a twin I was getting prop flutter and looseing the thrurst with the prop recomeneded. Swap to a 7x4 aps made a difference.

Darylm you might be right about the amp draw need to find the formula to figure it out the 10c battery might not be putting out enough c's to power the motors properly. isn't it 1.2x10= 12c if this is correct then you will puff the batteries.
yes, the formula would look like this

1.2ah x 10c = 12amps

so 12amps constant...
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Old 09-10-2009, 11:37 PM
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So maybe raflyer should try a 15c battery then the battery wouldn't be worked so hard and improve the engine output. Is this correct want to help him not mess him up.
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Old 09-11-2009, 02:08 AM
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raflyer
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I tried a 20C battery, no good. Same numbers to the 10C and 12C lipo's. I am thinking some APC6x4EP's may do the trick. (or 5x5??)
Here is the motor i am using,
http://www.dynamicfoamy.com/200%20brushless.htm

Thanks guys for your help. I really want to get this thing going before i take to the field and show it off.
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Old 09-11-2009, 03:15 AM
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Originally Posted by raflyer View Post
I tried a 20C battery, no good. Same numbers to the 10C and 12C lipo's. I am thinking some APC6x4EP's may do the trick. (or 5x5??)

Here is the motor i am using,
http://www.dynamicfoamy.com/200%20brushless.htm


Thanks guys for your help. I really want to get this thing going before i take to the field and show it off.
well, 15a = 7.5x2. so I guess it's within specs...

I'd try the 5x5e prop and see what happens... the lower size will boost the overall rpm's and the higher pitch should make it have a higher top speed...

SK
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Old 09-11-2009, 03:39 AM
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I found this motor, which looks like it's the same one... most people are running it on 2cells and an 8x4.3 prop, there doesn't seem to be much info on 3cells... although to me 180watts on a 19gram motor seems a bit much.... I don't think it would last long at that... best to Prop down to apc 5x5e if your going to stick to 3cells.... the other prop you might want to try is a 6x3e it might be slow overall, but it will have alot of thrust... which may help....

http://www.hobbycity.com/hobbycity/s..._19g_Outrunner

SK
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Old 09-11-2009, 04:22 AM
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I have 3 of these motors on foamies and usually run them on 2cell batteries, but I had one on a SU 26 outdoor foamie and tried a 1000 mah 25c battery and it flew like a different plane. Motor and ESC where just warm when I landed after an eight minute flight. I was running a 7x4 prop. I plan on getting a couple 500 mah 25c batteries for indoor flying this winter.
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Old 09-11-2009, 05:23 AM
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ian_ryeng
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Default please, correct me if i'm wrong...

I am sure that someone will correct me but based on the size and dimensions that you have stated (which sound huge) I would not imagine that this is enough power...

The motors you are using to my knowledge are not powerhouses, I do know that small brushless can be very picky and had a similar experience with a small balsa plane where a smaller higher pitched prop would work much better than a larger prop as the motor couldn't maintain a high enough rpm.

Do you have a tach to check the prop speed, just because you are measuring ~130W of power doesn't mean that it is being utilized efficiently, if you are working at a 50% efficiency then you really only have about 65W.

I hope that maybe this will help you find the problem and hope you can get it working soon!


-Ian


EDIT: The prop will have a huge effect as well, the cheap GWS props can have huge deflections and deformations reducing the pitch and efficiency. I tried them on a epp delta I have and the difference when I bought a 6x4E apc was night and day.
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