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« on: August 26, 2014, 05:49:10 AM »
Rajesh14305
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Hello .
Can any one tell me what will b the flight time of plane.with followings.
Auw 650grams.
1000mah 3cell 25c battery
106prop.1000kv motor.

Coz when i try to fly the motor stops giving thrust after 20sec with full throttle.(battery fully charged).and1min 26sec in 75 %throttle.can any one suggest any methord to increase flight time.is there something wrong with my battery
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« Reply #1 on: August 26, 2014, 07:23:13 AM »
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There are lot of factors affecting flight time, condition of battery, flying pattern are a few. however i owned a corro plane of similar setup and could get around 9mins on a no windy day. yours might vary largely WRT other factors.

Is the Lipo completely charged? whats the voltage and what is the recommended prop of the motor can you please give more details about ESC/motor/Lipo and their condition.

Ashok.P
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« Reply #2 on: August 26, 2014, 10:45:30 AM »
IndianHobbyShop
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At fully charged, please check the voltage of each cell (with a LiPo Voltage Checker/Alarm) and post the results here.
Do the same once the motor stops giving thrust and post the results.
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« Reply #3 on: August 26, 2014, 10:58:14 AM »
K K Iyer
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@rajesh14305,
You said 1000kv motor.
This description is inadequate.
Please see the wattage rating.
For the same rpm/volt, one motor may draw only 5amps while another draws 25amps or more.

A 1000mah battery rated at 25c is supposed to be capable of 25amps load.
At this rate 70% of the capacity will get used up in 1 minute 40 secs! (60min x 0.7 / 25)

That is in theory. In practice the battery may not be capable of more than 10c-15c (in this case 10-15amps). A motor/ prop combo drawing more than this will quickly pull the voltage (under load) to below 3.5v per cell, leading to premature death of the battery.

The other possibility is that one cell is weak and drops to 3v or less under load.

My guess about cause of your problem:
1. Motor too big, over 150-200 watts
2. Prop too big
3. One cell weak or cells not balanced
4. Though weight of 650gms is not high, wing area may be low, leading to high wing loading requiring full throttle to fly

Borrow a wattmeter to check current draw.
From my 1000mah 3s Zippy Compact batteries i normally draw upto 15amps in short bursts, and about 5-8amps for cruising. Average duration 6 minutes with 50% capacity remaining (over 11.4v or 3x3.8v after landing). I never run them down to below 11.1.
Motor Turnigy 2830 1000kv 210watts, prop ep9050.
Model AUW 650gms or 22oz, wing area about 3sqft (52"x8"), loading about 7oz/sqft.
Full throttle never needed. 45degree climbout on 50% throttle, cruise at 30%.

Hope this is of some help.
Regards.
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« Reply #4 on: August 26, 2014, 11:27:58 AM »
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I am using turnigy aero drive dst 1000 kv motor.and wolf pack 25c 3cell battery.while flying there was no wind at all.and my battery was showing 11.33 volts.my motors max amp rating is 14a.and recommended prop was 95.but still with that prop flight time is 1.26min at full throttle.my planes wing length is 1 meter and its breadth is 19 cm.fuse is 57 cm.think this will help to find out the problem
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« Reply #5 on: August 26, 2014, 11:32:16 AM »
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One thing i note that while charging the battery gets fully charged from 9 volts to full in just 6 or 7 minutes.can this b a problem
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« Reply #6 on: August 26, 2014, 11:32:52 AM »
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Was the voltage of the "Fully Charged" battery 11.33 volts?
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« Reply #7 on: August 26, 2014, 11:34:51 AM »
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Your LiPo is already damaged.
You should never let total voltage on a 3 cell LiPo go below 11.1 volts.

What's recommended is to keep track of the voltage of each cell using a LiPo Alarm, etc since it's a more reliable way to keep your LiPo's safe.
Get a LiPo alarm and a new LiPo.
http://www.quadkopters.com/product/1s-8s-low-voltage-alarm-indicator/
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« Reply #8 on: August 26, 2014, 11:38:59 AM »
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@rajesh14305
Oh oh. You have a problem.
At 9volts, the lipo is nearly dead.
11.4v is the voltage at which i land.
Full charge means voltage will be 12.5-12.6v.

Are you charging at a high rate? Higher than 1c? Do you have a balance charger?
Pl post pic of charger
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« Reply #9 on: August 26, 2014, 11:43:05 AM »
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Also post pic of battery.
Is it puffed up?
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« Reply #10 on: August 26, 2014, 12:00:59 PM »
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The reason why i keep on saying you want to go electric get a watt meter , rig up your setup and give full throttle it will show every thing you need the max amp bein pulled , the lowest your battery got under load , the watt rating . A simple watt meter saves you from this guess work
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« Reply #11 on: August 26, 2014, 01:52:52 PM »
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Reply # 45 onwards gives some guidelines

http://www.rcindia.org/electric-power/selection-of-motor-esc-prop-and-lipo-for-foam-planes/msg194309/#new
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