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Author Topic: prop size please  (Read 923 times)

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Offline propwash

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prop size please
« on: May 31, 2018, 14:57:48 PM »
I have small btushless motor a Turningy D2830/11 1000kv.
i am fitting it in a small sports type model. can some one suggest a suitable prop size. Thanks.
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Offline alangorham

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Re: prop size please
« Reply #1 on: May 31, 2018, 15:18:14 PM »
probably not, as you need to give more info:

How much ground clearance do you have?
What is the current rating of your ESC?
How many cells is your battery?
How heavy is your model?
When you say sports do you mean trainer/vintage style performance, or sport aerobatic type performance (ie odd loop and roll) or something else?

For example a 9x6 or 9x4.7 prop on 3s will probably give around 180W on a 3s Lipo. So if you had a 30A ESC you wouldn't stress it. But that's not the whole answer until you tell us what you want to achieve.
« Last Edit: May 31, 2018, 15:26:05 PM by alangorham »

Offline propwash

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Re: prop size please
« Reply #2 on: May 31, 2018, 17:03:23 PM »
Vintage Mercury matadore. plenty of ground clearance, weight ,about 1kg all up, thinking of 3cell , 30 /40amp esc.
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Offline PDR

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Re: prop size please
« Reply #3 on: May 31, 2018, 18:06:50 PM »
10-5 APC or similar as a starting point. Measure current, adjust to taste.

PDR
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Offline FlyinBrian

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Re: prop size please
« Reply #4 on: May 31, 2018, 19:01:14 PM »
Vintage Mercury matadore. plenty of ground clearance, weight ,about 1kg all up, thinking of 3cell , 30 /40amp esc.

Blimey - if your Matador does weigh c1Kg then you build heavy, I would have thought under 16oz / 450g would be nearer the mark
I built a ff version about 55 years ago and that weighed about 8 oz with a Mills .75
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Offline propwash

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Re: prop size please
« Reply #5 on: June 01, 2018, 09:57:05 AM »
Blimey - if your Matador does weigh c1Kg then you build heavy, I would have thought under 16oz / 450g would be nearer the mark
I built a ff version about 55 years ago and that weighed about 8 oz with a Mills .75

your'e right , Brian, , with battery and motor and two small servos it will be under 16 oz.
I didn't think it would be rocket science to size a prop.
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Offline propwash

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Re: prop size please
« Reply #6 on: June 01, 2018, 09:58:48 AM »
10-5 APC or similar as a starting point. Measure current, adjust to taste.

PDR

Thanks, I'll give it a whirl.
Well Flown? tell the wife.

Offline alangorham

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Re: prop size please
« Reply #7 on: June 01, 2018, 12:22:00 PM »
If your model did weigh 1 Kg as first suggested then I'd say a 10x5 on 3s would be a good start.

If it actually weighs less than half of that I would suggest a 10x5 prop on 3s will give you around 200W power and 200W/lb power loading which is rather too high for a vintage model - 60-70W/lb should be ample for that.

I'd now suggest either an 8 x 4 on 3s or the 10 x 5 on 2s.

Who mentioned rocket science?  $%& People have only tried to help!

Offline PDR

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Re: prop size please
« Reply #8 on: June 01, 2018, 12:37:12 PM »
It's a draggy aeroplane, so power/weight parametrics will usually underestimate. 200w on 3s gives the pilot the most flexible range of speed/climb/endurance options which can be selected via the throttle stick at will...

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Offline propwash

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Re: prop size please
« Reply #9 on: June 01, 2018, 16:37:03 PM »
If your model did weigh 1 Kg as first suggested then I'd say a 10x5 on 3s would be a good start.

If it actually weighs less than half of that I would suggest a 10x5 prop on 3s will give you around 200W power and 200W/lb power loading which is rather too high for a vintage model - 60-70W/lb should be ample for that.

I'd now suggest either an 8 x 4 on 3s or the 10 x 5 on 2s.

Who mentioned rocket science?  $%& People have only tried to help!

Thanks, that's helpful. most of my batteries are 3 s, so i'll go for 8*4
Well Flown? tell the wife.


 

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