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Old Jun 18, 2012, 08:07 PM
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What makes a jet fly fast?

So I'm still new to these EDFs. I have a 50mm F-22, 6 blade with 4S. How could I get more speed out of it? Does increasing the Kv of the motor and decreasing blades mean more speed? What about the opposite? Does decrease kv more blades mean more thrust and less speed? What determines how fast an edf flies (besides a less draggy airframe)?
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Old Jun 18, 2012, 08:21 PM
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Money!!
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Old Jun 18, 2012, 08:58 PM
deltas are cool
AIR SALLY's Avatar
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big batts rpm and good inlet and exhust ducting .
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Old Jun 18, 2012, 10:58 PM
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Pushing the throttle/ thrust lever's forward!!!!!!!
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Old Jun 19, 2012, 02:19 AM
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you need as much thrust as possible and a higher eflux....
eflux is the max speed you can fly ... thrust is the force that pushes you towards that speed
but there are other ways to make a jet to seem fly more faster like cocaine and lsd
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Old Jun 19, 2012, 03:53 AM
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+1 on the above but I think that the most significant is a slippery shape with the lowest drag. Composite airframes are usually "faster" than most foam airframes.

After that lower kv motors, higher cell count batteries give setups with manageable amps for more kWatts. Proper ducting and thrust tube give the eflux speed to achieve the top end speeds required.
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Old Jun 19, 2012, 04:16 AM
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Jet A1 !! and lots of it!
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Old Jun 19, 2012, 05:19 AM
Aka: Tom Jenkins
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Palm Beach County, Fl.
Joined Aug 2008
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Quote:
50mm F-22, 6 blade with 4S
Depends on what you may think as fast. A couple fellows have gotten a 50mm F-18 from nitro hobbies and they really fly well after adding a Don's fan system. An F-22 is lots of drag, I believe you could have three more toys by the time you spent enough to make it go fast. To answerer your question it takes rpm and enough motor, battery and ESC to sustain said rpm.
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Old Jun 19, 2012, 12:39 PM
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Quote:
Originally Posted by pylot2b View Post
Money!!
I have been wondering the same, and the answer has always come back to more dollars. You spend the right amount and get the right equipment, motor, batteries, esc, and yes, the right airfarme, then you get speed. By the way, my definition of speed for the edf is anything in excess of 150 mph. For the kero burners, 175 mph minimum.
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Old Jun 19, 2012, 01:22 PM
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Hmm if I increase the blades and lower the kv, wouldn't that produce more thrust which means more speed for a given airframe? How does that compare to high Kv decreased blades?

I guess money is the main factor. To support a big fast motor, need a good esc, and a good battery. All= money. Switch that foamy into composite and that's more $$$$
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Old Jun 19, 2012, 01:23 PM
Fight On!
mario alvarez's Avatar
San Salvador, El Salvador
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Aerodynamics.
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Old Jun 19, 2012, 01:45 PM
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I also have this question. I wanted to also know whether the blade count matters?
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Old Jun 19, 2012, 02:01 PM
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It's not a linear relationship, power and speed. If you double your power you will not double your speed. It takes almost a fourfold increase in power to double the speed. A well matched power plant to aircraft is what you should seek. Something light enough to allow slow speed flight, powerful enough for scale speed plus and efficient for decent flight times.
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Old Jun 19, 2012, 02:23 PM
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Hurst, Texas USA
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Does the pitch of the blades matter, or are they all the same ?
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Old Jun 19, 2012, 02:33 PM
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Yes, and they are definitely NOT all the same.
The blade width and shape are also factors.
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