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Have I enough power?

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Ronos28/01/2020 12:13:17
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Hello, I have a 5050/60 850kv Brushless motor with a APC 14x7 electric prop on a 80c ESC with a Turnigy 4S 5000mAh lipo, powering a VQ Hurricane 60 weighing in at 4.5kg. Please bear in mind that the power plant is recommended from the supplier. When powered up to full throttle there seem, in my opinion,not as much thrust as i would expect. Anyone got a opinion, just want to be sure before the maiden. Thanks Ron.

Edited By Ronos on 28/01/2020 12:15:59

Phil Green28/01/2020 12:33:29
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1640 forum posts
344 photos

What does your power meter read? You should be drawing over 60A to get a kilowatt from 4S.

smiley

Frank Skilbeck28/01/2020 12:35:17
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4821 forum posts
107 photos

Couldn't find your exact motor, but when I ran a 850kv motor through Ecalc with a 5000 mah 4s and APC 14 x 7, I got 5.2 kg static thrust, 10,000 rpm, 1400 watts and 100 amps. Have you checked the amps your set up is drawing

Dickw28/01/2020 12:37:16
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751 forum posts
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Can you give us more details on the motor please? I ask that because a quick check on the recomendations seem to suggest a 5055/06 580kV motor which has all the same numbers but not necessarily in the same order!

With an 850kV motor an 80A ESC might be in trouble.

Do you have any current or rpm readings from your test run?

Dick

Ronos28/01/2020 13:08:51
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214 forum posts
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Thanks for you all for your replies, can I get back to you later, I have a lipo on charge.

Ronos28/01/2020 13:13:57
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214 forum posts
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Frank, it's a Electrospeed brushless motor and Electrospeed ESC, supplied from Hobby Plastics.

Andrew Calcutt28/01/2020 13:16:08
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62 forum posts
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Get a quantum 60 motor on 6 cells that would give over 1500 watts and will fly it well.Any less than 1500 watts won't be enough.

PatMc28/01/2020 13:46:13
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4472 forum posts
548 photos

If this is the model then according to spec your's is about 1Kg overweight. I presume 850kv you quote is a typo, according to it's spec the recommended motor is 580kv . Which would suggest that it should be running on 6s for this model.
Unfortunately the motor spec doesn't mention it's max current but IMO the model would need it to be pulling in the region of 45A at WOT.

Ronos28/01/2020 14:00:07
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A quick confession, I not really sure on how the check for amps/ wattage,etc,etc, but I have just checked the rpm with a tachometer and divided it with the voltage of the battery, 8130rpm÷14.8v and it has came up with about 550 which I understand is the kv of the motor.

Ronos28/01/2020 14:03:42
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214 forum posts
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here is some more info on the motor.

KV 580rpm/v

power: 1280w

idle current: 2.3

esc 80A

Ronos28/01/2020 14:09:03
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214 forum posts
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Posted by PatMc on 28/01/2020 13:46:13:

If this is the model then according to spec your's is about 1Kg overweight. I presume 850kv you quote is a typo, according to it's spec the recommended motor is 580kv . Which would suggest that it should be running on 6s for this model.
Unfortunately the motor spec doesn't mention it's max current but IMO the model would need it to be pulling in the region of 45A at WOT.

Probably is over weight, I had to put in 40oz of lead to get it to its COG.

Bob Cotsford28/01/2020 14:12:28
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8757 forum posts
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Sorry but your 4S battery won't cut it. You need 6S aiming for a maximum peak of 50A with a fresh battery dropping down to the 45A PatMc quotes. When playing at this sort of power level a wattmeter is essential, without it you will have real problems as you are just taking a stab in the dark and hoping nothing goes pop. A wattmeter simply plugs between the battery and ESC and gives you a direct measurement of amps, volts and you guessed it, watts.

40oz of lead?  The 6S battery of around 4500mAH pushed as far forward as possible will help, but that is still a lot of lead.  Have you mounted servos in the tail by any chance?

Edited By Bob Cotsford on 28/01/2020 14:30:12

Ronos28/01/2020 14:12:36
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214 forum posts
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Posted by Dickw on 28/01/2020 12:37:16:

Can you give us more details on the motor please? I ask that because a quick check on the recomendations seem to suggest a 5055/06 580kV motor which has all the same numbers but not necessarily in the same order!

With an 850kV motor an 80A ESC might be in trouble.

Do you have any current or rpm readings from your test run?

Dick

Hi Dick just the rpm which was 8130.

Ronos28/01/2020 14:15:16
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214 forum posts
8 photos
Posted by Bob Cotsford on 28/01/2020 14:12:28:

Sorry but your 4S battery won't cut it. You need 6S aiming for a maximum peak of 50A with a fresh battery dropping down to the 45A PatMc quotes. When playing at this sort of power level a wattmeter is essential, without it you will have real problems as you are just taking a stab in the dark and hoping nothing goes pop. A wattmeter simply plugs between the battery and ESC and gives you a direct measurement of amps, volts and you guessed it, watts.

Thanks Bob, I will get one and get back to you all later. Thanks for all you help.

Ronos28/01/2020 14:34:59
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214 forum posts
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Posted by Ronos on 28/01/2020 14:15:16:
Posted by Bob Cotsford on 28/01/2020 14:12:28:

Sorry but your 4S battery won't cut it. You need 6S aiming for a maximum peak of 50A with a fresh battery dropping down to the 45A PatMc quotes. When playing at this sort of power level a wattmeter is essential, without it you will have real problems as you are just taking a stab in the dark and hoping nothing goes pop. A wattmeter simply plugs between the battery and ESC and gives you a direct measurement of amps, volts and you guessed it, watts.

Thanks Bob, I will get one and get back to you all later. Thanks for all you help.

Which watt meter would you recommend

Edited By Ronos on 28/01/2020 14:35:36

Nigel R28/01/2020 14:46:24
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4082 forum posts
694 photos

I make that about 10lbs in weight. Is it possible to relocate the lipo and loose all that lead?

The model's page quotes a 4S 5000mah and at the listed weight of 3.5kg that would make a lot of sense.

The IC engine range would suggest (max of .60 two stroke or .90 four stroke) shooting for about 1000W on the wattmeter.

1500W will be 3d capable, or, not entirely scale.

 

Using the rather useful prop power calculator shows your prop (14x7, 8100rpm) requires 750W of power at the prop; allowing for efficiency losses that would probably work out around 850W for the system as a whole.

I would guess 14x8, or 15x6, would set things right in terms of power output, but you absolutely do need a wattmeter to tell for sure.

Edited By Nigel R on 28/01/2020 14:51:04

Nigel R28/01/2020 14:49:11
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4082 forum posts
694 photos

**LINK**

4-max carry them

as far as I can tell, most of the <£30 units look to be very very similar in terms of buttons / display / etc.

Edited By Nigel R on 28/01/2020 14:50:23

Ronos28/01/2020 15:20:52
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214 forum posts
8 photos
Posted by Bob Cotsford on 28/01/2020 14:12:28:

Sorry but your 4S battery won't cut it. You need 6S aiming for a maximum peak of 50A with a fresh battery dropping down to the 45A PatMc quotes. When playing at this sort of power level a wattmeter is essential, without it you will have real problems as you are just taking a stab in the dark and hoping nothing goes pop. A wattmeter simply plugs between the battery and ESC and gives you a direct measurement of amps, volts and you guessed it, watts.

40oz of lead? The 6S battery of around 4500mAH pushed as far forward as possible will help, but that is still a lot of lead. Have you mounted servos in the tail by any chance?

Edited By Bob Cotsford on 28/01/2020 14:30:12

No servos in the tail and lipo as far forward as possible

Ronos28/01/2020 15:22:10
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214 forum posts
8 photos

Ordered a watt meter from 4 Max, see what the findings are.👍👍

Frank Skilbeck28/01/2020 16:09:39
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4821 forum posts
107 photos

On that motor the other option would be a 15 x 8 prop on a 4s which would give 4kg static thrust at 57amps or a 15 x 10 which would give 4.7kg at 67 amps.

The 14 x 7 will give around 3.2kg at 43 amps on a 4s or 6.1 kg at 82 amps on a 6s.

So if you go with a 6s then you could prop down a bit, say a 13 x 6, which gives 4.7kg at 60 amps, or go with a bigger prop on the 4s, but a 6s sounds a better option and remove some of that lead in the nose.

Note all the above are calculated results and should be confirmed by measuring the amps.

BTW we are just restoring a Mick Reeves Hurricane of a similar size and have gone with a 5060 380kv motor with a 15 x 10 prop on a 6s setup. Should be flying this spring once our strip has dried out and had a few rolls/cuts.

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