Help choosing the right propeller

Started by lastRites, October 09, 2012, 05:32:24 PM

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lastRites

October 09, 2012, 05:32:24 PM
What I have gathered from various threads is that in propellers, the diameter is linked with torque(thrust) and pitch is linked with speed. Now, motors have a a recommended propeller size that should be used for the most efficient setup. I have a few questions that I am not getting the answers to.. please help me out:
1) Suppose the max prop size for a motor on 3s is 7x4. Can we go to a 8x3 without putting undue stress on the motor?
2) Will a 7x4 and a 7x3.5 prop provide the same thrust when spun by identical motors on identical batteries with only difference in the top speed and power consumed?
Thanks,
Trishit  :)
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Of all things human and all things super-human,
Of all true manifestations of the head,
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jayantpradhan

#1
October 09, 2012, 05:51:31 PM
dude always use 6x4 props they are complete pakage for speed and aerobatics...... they never damage the electronics and even consumes less powers....
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saikat

#2
October 09, 2012, 07:26:31 PM
What you have asked is very general and impossible to answer empirically .
Try motocalc , it is a software specifically for rc electric flight

lastRites

#3
October 09, 2012, 11:54:20 PM
Quote from: jayantpradhan on October 09, 2012, 05:51:31 PM
dude always use 6x4 props they are complete pakage for speed and aerobatics...... they never damage the electronics and even consumes less powers....
6x4 props on both my 2200kv 340W motor and my 1450kv 655W motor ??? I need Maximum thrust :P
It is the pervading law of all things organic and inorganic,
Of all things physical and metaphysical,
Of all things human and all things super-human,
Of all true manifestations of the head,
Of the heart, of the soul,
That the life is recognizable in its expression,
That form ever follows function. This is the law.

lastRites

#4
October 10, 2012, 12:04:56 AM
I have a Turnigy aerodrive xp 102W 1100kv motor running on a 25c 1.6Ah lipo 20A esc. Recommended prop size 7x4. But I could only get 7x3.5 props. Will the thrust produced be the same with both the props? If speed(pitch speed) required is not that high can I put a larger prop on it with lesser pitch to increase the thrust produced without exceeding 102W??
It is the pervading law of all things organic and inorganic,
Of all things physical and metaphysical,
Of all things human and all things super-human,
Of all true manifestations of the head,
Of the heart, of the soul,
That the life is recognizable in its expression,
That form ever follows function. This is the law.

lastRites

#5
October 14, 2012, 12:20:31 PM
bump.. ;D
It is the pervading law of all things organic and inorganic,
Of all things physical and metaphysical,
Of all things human and all things super-human,
Of all true manifestations of the head,
Of the heart, of the soul,
That the life is recognizable in its expression,
That form ever follows function. This is the law.

anwar

#6
October 14, 2012, 12:44:55 PM
Quote from: lastRites on October 10, 2012, 12:04:56 AM
Will the thrust produced be the same with both the props? If speed(pitch speed) required is not that high can I put a larger prop on it with lesser pitch to increase the thrust produced without exceeding 102W??

If you read the Understanding Electric Power thread, all this would be clear from the get go.  Obviously, a smaller pitch prop will give you a slightly lower thrust, and it will also reduce your amp draw by a little bit. 

In terms of prop selection, look at the amp draw charts for your specific motor, which would tell you what is the amp draw for various props.  The sure fire way to confirm amp draw/load is by using a wattmeter.

Now all of this needs to be looked in the perspective of what you are using the power system for, especially the AUW.

BTW, where is this 102W motor available ?  A quick check, to see if there are prop selection charts for this particular motor, could not locate such a product on the HK website.
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lastRites

#7
October 16, 2012, 09:19:04 PM
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=18967
Going to use 4 of these on a multicopter weighing around 900gms so I need Maximum thrust :P
It is the pervading law of all things organic and inorganic,
Of all things physical and metaphysical,
Of all things human and all things super-human,
Of all true manifestations of the head,
Of the heart, of the soul,
That the life is recognizable in its expression,
That form ever follows function. This is the law.
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