Please help with some maths... (or math in the US!)

[Gunter]

Right now, I have mocked up the airframe and have some weights for my new airframe. I'm just hoping it's all going to work, I don't want to have to buy new motors!!

The airframe, motors, esc's, props, landing gear all weigh 2.3kg. I have to allow another 1kg for batteries, if I use 2 5000mah lipo's.

Props: Xoar 13x4
ESC's: 30A
Motors: 880kv AC2836 DIY drones, spec below:

1.5 A 17.5W 230gr	6.1 A 70W 650gr	14.2 A 160W 1290gr	20A A 210W 1380gr

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Edit: That actually doesn't copy and paste so well, the motor specs can be found here.

I am using a slighty larger prop to the spec above and I am planning on using 4S 5000mah batteries.

I am useless with the online calculator! All I am trying to find out is:

Will it fly?
What payload will it take?
Flight time?
Is there anything I can do to make it more efficient? Do I need to reduce the weight some more?

Thanks in advance,

Gunter.

View attachment 1148

 

[ovdt]

Hey Gunter,

You're over the limit accroding to ecalc, which I believe a very successful tool in evaluating this kind of combos.

* Your prop is big for that motor. It's gonna be very hot.I And I suspect your 30A ESC will handle that. f you lower the diameter of the prop, you won't have enough thrust power.

* If you add a camera, to this setup, let's say a Sony Nex5, you will reach a 4 kg total weight which makes this bird a mid-heavy bird.

* The easiest way to go is to change the motors. Avrotor 2814, Tiger Motor 2814, Pulso 2814/22 will work for you.

* Changing the frame and trying to reduce the frame will cost you more than 6 motors.

 

[jes1111]

I agree - everything's fine and dandy except those motors ---> Axi 2814/22 (or any of the equivalents as listed by @ovdt).

Then you'll be well in range for a light(ish) camera (i.e. not a 5DMkII) and 15 minutes in the air.

To use eCalc to help with these calculations, weigh the frame, landing gear, electronics, etc., add the weight of your intended camera and gimbal and enter that at the top ("without drive") - i.e. total weight without motors, ESCs and batteries. Then select your "drive" components (ESC, Motors, Battery [remember to select "full"] and Prop [use APC Electric E as rough equivalent to Xoar]) and you'll get an accurate picture of hover throttle (should be approx. 50%) and flight time.

 

[Gunter]

Thanks for the help guys. Could you suggest a motor that would be capable of lifting something a bit heavier, without breaking the bank? I would ideally like to carry about 1-1.5kg.

 

[Gunter]

I'm struggling to get my motor on the ecalc - it doesnt list my specific motor and I'm not sure what values to put in...

 

[jes1111]

RCTimer A-2836/9

Suggested replacements as listed by @ovdt - Avroto, Pulso, QC, Tiger, MK3638, etc. - they are basically all the same as the Axi 2814/22.

 

[ovdt]

RCTimer A-2836/9

Suggested replacements as listed by @ovdt - Avroto, Pulso, QC, Tiger, MK3638, etc. - they are basically all the same as the Axi 2814/22.

Jes, as far as I know, RC Timer doesn't has A2836/9.

They have BC2836-9 (which have 10 of them ), and I suspect they would be enough for Gunters. Did you mean A-3536/9 or BC3536-11?

http://www.rctimer.com/index.php?gOo=goods_details.dwt&goodsid=399&productname=

[URL="http://www.rctimer.com/index.php?gOo=goods_details.dwt&goodsid=509&productname="]http://www.rctimer.com/index.php?gOo=goods_details.dwt&goodsid=509&productname=

[/URL]I own Tiger, Mikrookpter MK3638, Axi 2814/22 and several RC Timer (BC2836 and BC3536-11). For the price/performance, I'd go with Tiger Motor, I liked their quality. You can purchase them less than half price of Axi.

 

[jes1111]

I'm not at all familiar with RCTimer - I just found that in the eCalc list: it seems to be the motor that Gunter has now (or the equivalent thereof).

View attachment 1157


The Tiger motors do look interesting (the whole range) - and they look pretty cool as well

 

[Gunter]

Thanks again for the help. I will fly initially with the 880kv motors, but just leave off the camera and anything else that doesn't need to be there. I'll see what the Tiger motors cost in the UK...

 

[jes1111]

Not a good idea, Gunter! Those 13" props are just too much for those little 70g motors. Swap to 10" or 11" and fly with a single battery

 

[BorisS]

honestly I think the Rc tigers motors are the same like the QC just adjusted some specs thats it ! If i somehow get my hands on them, they dont want to sell to me directly since they have a distributor in germany i will test them, but ovdt already has his hands on them !

 

[Droider]

Geoff at QC.co.uk has some on there way. He has had them made especially for MR's. They have VERY high quality components and the windings look amazing. I have seen the protortypes fly and they are pretty amazing. He had some 13" carbon props on his HL quad and when he hit the gas.. well it space bound very quickly.. I think he will have them to show off at the UK meet.

Dave

 

[Gunter]

Not a good idea, Gunter! Those 13" props are just too much for those little 70g motors. Swap to 10" or 11" and fly with a single battery

Thanks for the suggestion Jes, I'll see if I can get some smaller cheap props in the meantime.

Motor wise, I expect I couldn't go wrong with the Quadrocopter.us motors: (not the actual motor from them, but a similar motor with the same spec at a much better price!)

Technical Info

• Lithium cell count: 3-6
• Load current: max. 30A
• Maximum load current. (15 sec): 50 A
• No-load speed: 700 rpm / V
• Recommended Propeller Size: 10" .. 14"
• Mechanical power: 350 W
• Thrust max.: 2200 g
• Wire length: about 60cm
• Total weight (without cable): approx 105g (139g with prop adapters, 600mm wires, and bullet connectors)

Thanks

Gunter.

 

[Gunter]

Geoff at QC.co.uk has some on there way. He has had them made especially for MR's. They have VERY high quality components and the windings look amazing. I have seen the protortypes fly and they are pretty amazing. He had some 13" carbon props on his HL quad and when he hit the gas.. well it space bound very quickly.. I think he will have them to show off at the UK meet.

Dave

Haha, posted at the same time about the same thing

 

[BorisS]

Thanks for the suggestion Jes, I'll see if I can get some smaller cheap props in the meantime.

Motor wise, I expect I couldn't go wrong with the Quadrocopter.us motors: (not the actual motor from them, but a similar motor with the same spec at a much better price!)

Technical Info

• Lithium cell count: 3-6
• Load current: max. 30A
• Maximum load current. (15 sec): 50 A
• No-load speed: 700 rpm / V
• Recommended Propeller Size: 10" .. 14"
• Mechanical power: 350 W
• Thrust max.: 2200 g
• Wire length: about 60cm
• Total weight (without cable): approx 105g (139g with prop adapters, 600mm wires, and bullet connectors)

Thanks

Gunter.

Gunter which ones are those ? if not the QCs

 

[Gunter]

Gunter which ones are those ? if not the QCs

Boris, they are the ones from quadcopter.co.uk, they haven't gone on sale yet, but Geoff has said they will be there soon!

Gunter.

 

[Borneoben]

Hi Guys

I am also in a similar position to Gunter choosing a Motor for my home designed Y6 Hexacopter.

After a recommendation from OVDT (top man) I also looked into Tiger motor. I contacted them directly through thier website and i must say that they have been extremely professional and friendly and the prices are pretty good.

I live in the middle east and there are no distributors near by so i can deal direct. The speed of the responses for technical questions and the motor prices and the shipping prices have all been a reall nice suprise.

I get so upset with poor customer service that when you get good customer service i make a point of telling them and thanking them.

So here is my Public thank you to RCTiger Motor and the representative called Julia Yong!

I willbe placing an order for 6 MT2826 and maybe even their 40amp escs which are priced very similar to Hobby Wing and Turnigy Plush series.

I am waiting to hear if these ESC will handle the same signal input frequency as the ever popular Turnigy Plush and Hobby wing ESCs. If so then i will buy them to test out.

Cheers all

Ben

 

[Gunter]

Good to hear that there are still some good companies out there!

 

[ovdt]

Berneoben,

If you're willing to use MT2826, just be sure that you have enough long arms to carry at least 13" props. Since the KV value is low on MT2826, you will need bigger props to have enough thrust on these motors. I would recommend 14x4.7, 14x4 or 13x6 with MT2826. Even you use 15" prop on MT2826, 40A ESC will be more than enough.

If you haven't ordered yet, take a look at their MT2820/830KV. It's lighter and yet powerful. But, you will need to use 12" prop not to exceed 40A limit of the ESC. Take a look at xcalc, you can choose AT2820 for evaluation. And see how the power consumption changes with motor / prop combinations.

If you tell me the weight of your copter without the camera, we can discuss further. I like talking about motors, props and weight )

 

[Borneoben]

Hey OVDT

Yes i am planning on the MT2826 motors at the moment with 40amp ESC's

My weight estimates for my airframe including camera mount and camera are roughly 3Kg!

Airframe alone is roughly 1.5Kg and the camera mount including 550D is also roughly 1.5Kg

That does not include Motor's, ESC's, or Batteries.

I was planning on using 14x4.7 props and 2x 4s 5000mah flight packs in paralell.

I think an all up flying weight would be roughly around 5.6Kg!

These are all estimates as its all still on the drawing board.

You have already helped me recently with ecalc and the MT2826 motors look like a good match. But i am willing to listen to other sugestions!

Cheers

Ben