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Old Aug 12, 2011, 11:03 PM
Physics hate's my ideas
GreenAce92's Avatar
USA, NY, Dunkirk
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Long duration high speed EDF's do they exist?

I'm starting to get into FPV flying and I'm looking for speed and duration!

EDF's seem to be best for high pitch speed...

I've got a design I'm thinking about doing however I should know first if an EDF would be worth looking over for an FPV plane

Say 70mph at least (not full power) and say a flight time of at least 15 minutes
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Old Aug 12, 2011, 11:31 PM
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racer1's Avatar
United States, AZ, Tucson
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Stick with props, EDF are not efficient in any way shape or form.
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Old Aug 12, 2011, 11:36 PM
Physics hate's my ideas
GreenAce92's Avatar
USA, NY, Dunkirk
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Says the guy with an EDF for an avatar...

What if you took that air frame (for example the one you have) and then put a small high pitch prop on there...

Better results?
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Old Aug 12, 2011, 11:46 PM
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St.Catharines, Ontario
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deffinitely better results. but define better. better slower top speed, or better more endurance? you'll get more work done on less amps, but not as high in the speed range. for FPV, I'de stick with prop. unless you've got big glider-like wings and can fly slow, power down, then dly slow, it might be a good way to go. think of the UAV Predator. something like that. if you wanna go fast, your flight times will be a lot less. somewhere around 7 minutes or less, depending on battery size. I'de go with a prop, based on those flight times. EDF is unrealistic at that speed range, unless you are willing to make it into a glider, as suggested above.
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Old Aug 12, 2011, 11:51 PM
Physics hate's my ideas
GreenAce92's Avatar
USA, NY, Dunkirk
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An EDF glider?
What about a high aspect ratio glider, which can glide because of the high loading on the wings = better L/D ratio

I had this idea for a variable EDF intake which could be closed when you don't want the EDF to be in use, so the EDF is basically sealed off and the glider has clean aerodynamics (as good as it gets)
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Old Aug 12, 2011, 11:53 PM
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To fly jets using a fan systems, it is usually lots of small props tied together to make a fan, high rpm for thrust, lots of amps to do it with.

Larger prop, lower rpm, lower amps.

If you are posting here you must have some experience with EDF, then you know we have been searching long flight times for awhile. 4 to 6 minutes is all we get with good throttle management.

If you can figure out the setup you want, I am sure you could sell a few.

Good luck
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Old Aug 12, 2011, 11:56 PM
Physics hate's my ideas
GreenAce92's Avatar
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Well... my experience is nil almost none...

I had a cheap model of an Albatross once a little 2ch thing

Not really the same as a 70mm fan

What kind of rpms are we talking about here anyways?
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Old Aug 13, 2011, 12:03 AM
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My 5 inch Dynamax, 12s, 25,000 rpm 110 amps

Vio fan, 12s 27,500 rpm 144 amps

Modified Ramtec 12s 26,000 rpm 128 amps

90 mm Fan 6s 34,000 rpm 65 amps

My friends flying wing FPV- UAV 4s, 14 inch prop, 45 minutes plus flying time.

Just some numbers for you, to think about
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Old Aug 13, 2011, 12:08 AM
Physics hate's my ideas
GreenAce92's Avatar
USA, NY, Dunkirk
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Hmm... So EDF really doesn't have a chance?

Even if, let's say you take a hot liner body, have an EDF motor with a gate for both the intake and the outtake (exhaust?)

That way you can seal the engine up to be a complete pod which has no holes for drag...

How much does efficiency drop when you change the intake hole/outtake hole from a complete circle to say a flattened ellipse... ?
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Old Aug 13, 2011, 12:13 AM
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Hotliner is just a special glider.

10 to 15 seconds of full power, climb out of sight then glide around, then power up, and repeat.

Get the right setup, prop for best speed at the lowest current/amp draw.

Use a Castle Creations Ice controller and you can download the data and look at rpm, amp draw, etc.

There is no right answer, you will have to find the setup you want, I am sure you can find better answers in the glider, or prop sections, or the FPV-UAV sections, good luck.
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Old Aug 13, 2011, 12:14 AM
Not Funny......
Mike Warren's Avatar
United States, CO, Redstone
Joined Dec 2010
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Quote:
Originally Posted by GreenAce92 View Post
Well... my experience is nil almost none...

I had a cheap model of an Albatross once a little 2ch thing

Not really the same as a 70mm fan

What kind of rpms are we talking about here anyways?
69mm fan typically 45,000 up to around 60,000RPM

Big fans, like Clay says.....25,000RPM or a bit more

Forget EDF for "speed + long flight times", the system is meant to replicate jet like flight and has to achieve it by pouring (compared to props) gobs if power into a less "efficient" setup.
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Old Aug 13, 2011, 12:17 AM
Physics hate's my ideas
GreenAce92's Avatar
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That's too bad

I think I may just go with a folding prop type deal, where I can have a good constant "on" time and then turn the motor off and glide.

I appreciate the input guys, I'm glad I didn't waste the effort in materials to find out this answer
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Old Aug 13, 2011, 07:52 AM
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The simple answer is low wing load...as low as possible...I can get around 10mins out of the Tieseng 70mm T-45 if I only did a couple of high speed passes but the rest of the time I let it float when using 4000mah battery.

15min is something you'd get out of a glider with a fan on it but as mentioned before you're erasing speed.

HK does sell a 70mm edf global hawk with 80" wing span, don't now if it'll go 70 plus.
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Old Aug 13, 2011, 07:54 AM
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not even close. 50MPH tops and that's only if you dive down from about 5000 feet to get there. LOL.
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Old Aug 13, 2011, 02:34 PM
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United States, WV, Calhoun
Joined Nov 2004
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Take a look at the Great Planes Syncro. It is an EDF and has sailplane wings.

I have one and on a 3 cell 2600 it gets flight times of 20 minutes with the motor running. But the speed is way below 70 mph. At full throttle it will fly pretty fast.

It is heavy so it does not soar all that good. But if you float around awhile with the 2600 battery 30 minutes flights are pretty easy to achieve.

The quality on the Syncro is excellent. And it is a great flier. So if you need an EDF the Syncro might work for you.

There is a thread on it here in this forum as well as the electric sailplane forum.

Todd
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