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Old Jan 05, 2011, 10:05 PM
Ugly planes do not fly
_Sergey_'s Avatar
USA, GA, Alpharetta
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Selecting power system

After couple of days of research here is the list of power options I found. By all means this is not everything but rather an attempt to find a suitable scale sounding power plant. I got my eye on 8 blade fan. People are saying it sounds closest to the turbine, or I'd say less reminding a Hoover vacuum cleaner

There are two 8-blade fans on the market. One is DF70 from BP Hobbies and another is Skyworld fan.

DF70 fan
Name: DF70Parts.jpg
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Description: DF70 fan

Skyworld aluminum fan
Name: Skyworld_70_8blade.jpg
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Description: Skyworld fan

There are very little test data available for 8 blade fans. One test was done by St. Martin here.

HET 2W, 40c 2200 3s, 52A @ 510W.

St. Martin recommends using 2200 4S setup with HET 3W motor. The amp draw will be 35A @ 450W average. It will be much more efficient set up than 3S.

ExtremeRc suggests using 2W20 motor on 4S. This setup will be more powerful than 3W but reasoning behind is one can always cut on throttle for scale flying and only use more power when needed.

EffluxRc recommends set of ARC motors to use.

There are three different recommendations but they all have one thing in common - use 4S setup because it will be more efficient, draw less amps, less heat, and can be actually lighter than 3S.

I personally having hard time to decide between 3W and 2W20.
* 3W will most likely be most efficient, work at its max RPMs (better for ESC), lighter by 15g and $15 but will spare almost no reserve power when things happen.
* 2W20 has wider power envelope but heavier, more expensive and less scale in terms of thrust/weight ratio.

So here is the list of motors with prices, Kv and power limits.
Name: Motor Selection.png
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Description: Motor selection

What do you think?
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Old Jan 05, 2011, 10:13 PM
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Sergey I am using 2w Het on a 3s set up as it will give you more than enough thrust keep in mind that this plane is very light and you don't want to over power her as she would NOT fly scaled. The 2w-20 is a 4s setup. You really don't need more than 3200-3600kv or (500w). If you chose to run a 3s setup I would recommend getting the same setup as me which is a 2w HET on 3s 3300mAh which will give you 1:2 ratio not bad I think
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Old Jan 05, 2011, 10:18 PM
Ugly planes do not fly
_Sergey_'s Avatar
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Rookie, what fan are you using?
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Old Jan 05, 2011, 10:22 PM
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I am using HET 65 ESC and EDF 6904 fan unit
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Old Jan 05, 2011, 10:22 PM
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thats about 2lb of thrust each power plant! I think the plane weigh around 2.97lb almost 3lb but dont qoute me on that as I may be wrong.
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Old Jan 05, 2011, 10:32 PM
Ugly planes do not fly
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Quote:
Originally Posted by Rookie2008 View Post
thats about 2lb of thrust each power plant! I think the plane weigh around 2.97lb almost 3lb but dont qoute me on that as I may be wrong.
I'd say plane is around 6.6lb AUW
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Old Jan 05, 2011, 10:35 PM
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O wow than in that case its up to you if you want to go with the 2w-20 than it should give you around 3lb of thrust so you would be looking at a 1:1 thrust/weight ratio but I am going to stick with my 2w 3s setup on 3300mAh.
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Last edited by Rookie2008; Jan 05, 2011 at 10:44 PM. Reason: update
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Old Jan 05, 2011, 10:41 PM
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If you wanted to go with a 4s setup the Het 2W-20 with at least a 75esc would fly a 9lb plane very scale so that gives you an idea how much thrust you would be getting with a HET 4s setup on 3300mAh at or around 4-5min of flight time at 1/2 throttle
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Old Jan 05, 2011, 10:58 PM
WIFE HAND LAUNCHED MY PLANES!
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Quote:
Originally Posted by _Sergey_ View Post
After couple of days of research here is the list of power options I found. By all means this is not everything but rather an attempt to find a suitable scale sounding power plant. I got my eye on 8 blade fan. People are saying it sounds closest to the turbine, or I'd say less reminding a Hoover vacuum cleaner

There are two 8-blade fans on the market. One is DF70 from BP Hobbies and another is Skyworld fan.

DF70 fan
Attachment 3708189

Skyworld aluminum fan
Attachment 3708191

There are very little test data available for 8 blade fans. One test was done by St. Martin here.

HET 2W, 40c 2200 3s, 52A @ 510W.

St. Martin recommends using 2200 4S setup with HET 3W motor. The amp draw will be 35A @ 450W average. It will be much more efficient set up than 3S.

ExtremeRc suggests using 2W20 motor on 4S. This setup will be more powerful than 3W but reasoning behind is one can always cut on throttle for scale flying and only use more power when needed.

EffluxRc recommends set of ARC motors to use.

There are three different recommendations but they all have one thing in common - use 4S setup because it will be more efficient, draw less amps, less heat, and can be actually lighter than 3S.

I personally having hard time to decide between 3W and 2W20.
* 3W will most likely be most efficient, work at its max RPMs (better for ESC), lighter by 15g and $15 but will spare almost no reserve power when things happen.
* 2W20 has wider power envelope but heavier, more expensive and less scale in terms of thrust/weight ratio.

So here is the list of motors with prices, Kv and power limits.
Attachment 3708190

What do you think?
SO YOU ARE INTO TURBINE SOUND!
I will be building my next AIRBUS once the 70mm is released on MOTO-TURBINE.


The 64 mm is now released for $55 complete, assembled.
The heck iS MOTOTURBINE?


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In conventional ducted fan design, the motor is secured to the stator hub while the fan secured to the motor shaft. During operation, any imperfection in either the motor or fan will cause both the fan and motor to vibrate at a certain resonance frequency. The oscillation can cause the blade tip to rub against the shroud of the duct. Moto-turbine’s 3-bearing system reduces resonance vibration by 90%.

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spyro
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Last edited by Spyro37; Jan 05, 2011 at 11:08 PM.
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Old Jan 05, 2011, 11:05 PM
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Spyro, Sir if you want a turbine sound go with Stumax fans 11 bladed fans enclosed a video

Stumax SM110-52 bench test (0 min 54 sec)
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Old Jan 05, 2011, 11:07 PM
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They are expensive as I am on a waiting list for them in the new 90mm setup. but you have to use neu motors of the 700-68 series HET motors But stew has not yet made them in 70mm as he is behinf on the 90mm but when he does they will be the best sounding edf fans i have ever heard

Now that electric turbine!
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Old Jan 05, 2011, 11:11 PM
WIFE HAND LAUNCHED MY PLANES!
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Quote:
Originally Posted by Rookie2008 View Post
They are expensive as I am on a waiting list for them in the new 90mm setup. but you have to use neu motors of the 700-68 series HET motors But stew has not yet made them in 70mm as he is behinf on the 90mm but when he does they will be the best sounding edf fans i have ever heard

Now that electric turbine!
Then I will get the MotoTurbine 1200 (120mm)
and I'll see you at Van Nuys. LOL
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Old Jan 05, 2011, 11:14 PM
Ugly planes do not fly
_Sergey_'s Avatar
USA, GA, Alpharetta
Joined Mar 2007
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I guess it's time to make an experiment

I have A380 which is close to B737 and flies extremely scale!

So I hooked up a watt meter and at full throttle I've got 500W. The Airbus' AUW is 4.4lb which makes a scale airliner watt per pound ratio = 114.

So... for 737's 6.6lb AUW the most scale power is 375W per motor. Voila!
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Old Jan 05, 2011, 11:15 PM
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LOL you win!!!!!
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Old Jan 05, 2011, 11:18 PM
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Sergey I have the A380 also an in that case thats 750 wats total right the 2w setup i am using will give me 1000 watts between the (2) motors and if you went with the (2) 2w-20 it will give you 1600 watts.
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