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Old Nov 01, 2011, 12:29 PM
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United States, TN, Jackson
Joined Mar 2007
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Originally Posted by therealhiphop View Post
Is it just me, or is there a significant gap between the blades and the shroud?
I would run the fan up to see if the blade to shroud large gap was done intentionally due to blade stretch....Blades can vary in stretch due to the material they are made from, thickness, etc...Those blades look pretty thin---Someone run one of these up with a high power setup and report back if there is significant blade stretch...Tell us the RPM, Amps, and thrust if possible...

Kevin
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Old Nov 01, 2011, 01:24 PM
Flying!!! Got to love it
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USA, PA, Philadelphia
Joined Jun 2006
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Quote:
Originally Posted by therealhiphop View Post
Radio56 is that the older SAPAC motor? I think I have that same motor. It's what I got when I bought my L-39, before they started using the blue, MB1 motors.

How is the fit?
Yes, It's the motor that came with the Jas-39 and a few others from Sapac. I think it was the first one they came out with. You had this motor all silver then came the black one and last was the MB-1 that is blue. It fit real nice.

Keep em flying
raido56/ Herb
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Old Nov 01, 2011, 01:35 PM
Flying!!! Got to love it
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USA, PA, Philadelphia
Joined Jun 2006
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Quote:
Originally Posted by Eddie P View Post
What's the first picture showing with the spinner that looks concave? Is that an optical illusion, or? What type of fan adapter is included? Collet, or set screws - and what's the shaft size for the adapter?

Have you run it up yet?

Yes, It's an optical illusion, took the pic from head on on macro setting. Shaft adapters are set screws. You get a 3mm and 4mm adapter. No not yet sometime this week. Going flying today for sure.

Keep em flying
raido56/ Herb
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Old Nov 01, 2011, 03:57 PM
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Wow, got mine today...but my radio is down...
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Old Nov 01, 2011, 04:48 PM
Wilde Sau
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Germany
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Guys,

does anyone know a good website to read up on the theory of EDFs? Especially about required airflow, cheater holes etc.?
Wanna know what it takes to get a Me262 model airborne while using EDFs and still keep the kinda tiny scale dimensions of the engine inlet. Every ARF model out there of that plane that uses EDFs has greatly enlarged inlets which I don't like at all...

Cheers,
Bernhard
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Old Nov 01, 2011, 04:54 PM
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Originally Posted by Beltpilot View Post
Guys,

does anyone know a good website to read up on the theory of EDFs? Especially about required airflow, cheater holes etc.?
Wanna know what it takes to get a Me262 model airborne while using EDFs and still keep the kinda tiny scale dimensions of the engine inlet. Every ARF model out there of that plane that uses EDFs has greatly enlarged inlets which I don't like at all...

Cheers,
Bernhard
I don't think there is a certainized thread, but...


Basically, You want to know what FSA is. FSA means fan swept area, basically the area of the fan where blades are spinning.

so you have a 70mm fan, with a 28mm motor. you want to find the area of the 70mm tube, minus the area of the 28mm motor tube. This is basically, the area that the fan is "sweeping"

For ducts and inlets, you really don't want less than 70%FSA. 100% FSA is good, but you can easily get away with 80-90% if scale demands it. That's the simplest way to understand what the fan needs.

As far as power, most EDF will fly good on 200 watts per pound. IMHO, that's around the best spot for sport flying. Some bigger models can get away with less, and lots of models have more

I hope that helps!
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Old Nov 01, 2011, 04:56 PM
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Also, it would help if you posted the Size you want this 262 to be. a couple of 70mm fans on 1400 watts each will give you about 8 pounds thrust, which would fly a good size model.

a pair 90mm fans on 1900 watts each would give you +12 pounds thrust. that would fly a BIG model.

it all depends on how big you want the model to be.
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Old Nov 01, 2011, 05:07 PM
Wilde Sau
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Germany
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Thanks guys!
Good info!

Well, the model in question would have to be a 1400-1500mm span Me262 made out of EPO, with an AUW of around 8lb I guess...
Power would have to be good for scale flying, and the setup should run on 4S if possible... that's why I thought 70mm EDFs...

Cheers,
Bernhard
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Old Nov 01, 2011, 05:10 PM
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United States, TX, Grand Prairie
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Originally Posted by Beltpilot View Post
Guys,

does anyone know a good website to read up on the theory of EDFs? Especially about required airflow, cheater holes etc.?...
I see what you're saying, my understanding of turbines is if air is rammed into them at 700+ they'd start rpm run away or would go lean so it was best to constrict inlets at certain speeds.

EDFs on the other hand want as much as in as could get, with a scale like inlet you might get much better influx but static thrust would suffer etc.

I've seen cheater holes cut an 1/2 to an inch in front of the fan shroud to keep the intake area intact and then a screen to hide it.

For the ME262 I'd do the same on the bottom of the nacelle to hide it, put a slight angle into the cheater "square" and round off the corners...the smoother the airflow the better

If it hides pretty good put one on top too...don't forget about the in angle
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Old Nov 01, 2011, 05:24 PM
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Quote:
Originally Posted by Beltpilot View Post
Thanks guys!
Good info!

Well, the model in question would have to be a 1400-1500mm span Me262 made out of EPO, with an AUW of around 8lb I guess...
Power would have to be good for scale flying, and the setup should run on 4S if possible... that's why I thought 70mm EDFs...

Cheers,
Bernhard

Alright, Assuming you want to use these 10 bladed fans....

According to my calc, an an ARC 28-47-1.5 (2800kv), this fan will pull about 67 amps and right at 1000 watts on 4S. This should give you about 3 pounds thrust. This are just estimates, i don't have my hands on this fan yet, but i used the first posts amps/watts as a baseline (3200kv and 1400 watts, 100 amps).

Two of them would give you 6 pounds of thrust, maybe closer to 7, we'll have to wait until there is more testing on this fan to know for sure.

This should power a scale model pretty well, i would think. Although i personally would opt for atleast 1:1 thrust to weight. But most of my jets are sport jets, so take the 1:1 suggestion with a grain of salt.
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Old Nov 01, 2011, 05:32 PM
Wilde Sau
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Germany
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Quote:
Originally Posted by erh7771 View Post
For the ME262 I'd do the same on the bottom of the nacelle to hide it, put a slight angle into the cheater "square" and round off the corners...the smoother the airflow the better

If it hides pretty good put one on top too...don't forget about the in angle
That's what I thought... cheater holes would help. What do you mean with "in angle"?

Quote:
Originally Posted by gundamnitpete View Post
Alright, Assuming you want to use these 10 bladed fans....

According to my calc, an an ARC 28-47-1.5 (2800kv), this fan will pull about 67 amps and right at 1000 watts on 4S. This should give you about 3 pounds thrust. This are just estimates, i don't have my hands on this fan yet, but i used the first posts amps/watts as a baseline (3200kv and 1400 watts, 100 amps).

Two of them would give you 6 pounds of thrust, maybe closer to 7, we'll have to wait until there is more testing on this fan to know for sure.

This should power a scale model pretty well, i would think. Although i personally would opt for atleast 1:1 thrust to weight. But most of my jets are sport jets, so take the 1:1 suggestion with a grain of salt.
OMG, only 3lb thrust at 2800KV 1000watts/67amps? The total ampdraw on this bird then would be 134amps, and that would result in less then optimal power as I would also aim for 1:1 weight:thrust.
That kind of ampdraw would suck a 4S 3600mAh battery dry in far less than 2 minutes... no option
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Old Nov 01, 2011, 05:48 PM
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Quote:
Originally Posted by Beltpilot View Post
That's what I thought... cheater holes would help. What do you mean with "in angle"?


OMG, only 3lb thrust at 2800KV 1000watts/67amps? The total ampdraw on this bird then would be 134amps, and that would result in less then optimal power as I would also aim for 1:1 weight:thrust.
That kind of ampdraw would suck a 4S 3600mAh battery dry in far less than 2 minutes... no option
A single 4S 3600 most likely wouldn't have enough juice for an 8 pound aircraft with edf they are not the most efficient aircraft.

If you have two, a 4S 6200 would give you 4 minutes with throttle management.

However, a pair of 90mm fans might be a better option. This however, would require larger batteries. thus the weight would go up
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Old Nov 01, 2011, 05:58 PM
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Skunk Water, Rhode Island
Joined Jul 2002
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Quote:
According to my calc, an an ARC 28-47-1.5 (2800kv), this fan will pull about 67 amps and right at 1000 watts on 4S. This should give you about 3 pounds thrust. This are just estimates, i don't have my hands on this fan yet, but i used the first posts amps/watts as a baseline (3200kv and 1400 watts, 100 amps).
Pete a ARC 28-48-1.5 does 57A@1075W on a 5s, in a WM-400MK II. I have two in my Cutlass. This fan really pull that much more and on 4s?

Fuzz
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Old Nov 01, 2011, 05:59 PM
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Quote:
Originally Posted by St. Martin View Post
Pete a ARC 28-48-1.5 does 57A@1075W on a 5s, in a WM-400MK II. I have two in my Cutlass. This fan really pull that much more and on 4s?

Fuzz
the original poster is claiming 1400 watts on a 3200kv sapac MB-1. I mean, it does have double the blades of a wemotec.

I'm just estimating right now based off numbers i've seen in this thread, haven't tested it yet myself.
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Old Nov 01, 2011, 06:00 PM
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Champaign, Il
Joined Mar 2008
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A different fan with less blades will probably get you where you want. This one is going to pull more amps than a 5 blade fan. You could run a 5 blade (or less)fan with a higher Kv motor and produce more watts for less amps. For a scale'ish intake a high kv 68mm fan with an intake of around 85% would work, no ugly cheaters. Heck I have a 70mm version in the works and the intake isn't too bad looking. I don't have my numbers in front of me, but I am thinking that it would get the thrust you need.

Matt
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