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Apr 19, 2004, 02:33 PM
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Fishnut's Avatar
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Put way more FUN in the fun jet


Just got back from a wonderful maiden of TOGís re-engined FFFJ50 (swept/aileron).

Iíve been making brushless outrunners from gobrushless.com for maybe a month now and wondered what it would be like to make a hot one and stick it in an EDF. Well I did and Holy $&%*! Five.something amps and 37K RPM on 25T 26G 6 magnet delta and 3s Kokam 340s. Given that I began cautiously with 25 turns, thereís a lot more RPM where that came from.

Anyway the thrust is not quite 1:1, but almost. The FFFJ was an absolute dream in the sky. I mean it was fun before, but the extra thrust and speed were just the ticket to make this rascal a real graceful aerobat. Now I wish I did more to reinforce the wing joint.

Iím gonna order a couple of each size EDF and go to town.

Thanks for this wonderful design TOG.

Here's a couple pics. This really wasn't even flight weight mounting hardware or anything, but I just had to see what it would do. Shoot, even if I got NOTHING more from this setup, I'd be a happy camper.

Kurt
Last edited by Fishnut; Apr 19, 2004 at 02:40 PM.
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Apr 19, 2004, 04:23 PM
"I passed on the kool-aid"

How fast are we talking about here?


I have not built the fun jet (yet) but built TOG's F-16. All I had was a 2 cell etec 1200 which was too heavy. It would only go about 75 yards before losing altitude slowly and landing. It was fast though and I think a 2 or 3 cell 340 pack with a hot CD-rom motor would be amazing. The roll rate was unbelievable on the one I built...of course I ignored TOG's recommendations and gave the ailerons about 3/8"-1/2" deflection which was way more than needed but it sure was fun. Hope to get some old drives tonight to play around with and maybe rewind a motor. What controller are you using. Keep us posted of the specs you are using as I am wanting to build a hot one for a 24" EPP wing I have.
Apr 19, 2004, 06:12 PM
Foam rules
Thatovalguy's Avatar
To bad the motor blocks the fans outlet or it would have even more thrust. Maybe you could build a shroud to smooth the air flow past it. Its got to be like blowing on a brick wall. Still its got to be WAY better than these stock motors.

papasmurf, 340's is the ticket for the F-16. I do fly once in a while using a 600 but it really only flys, not to pepie.
Last edited by Thatovalguy; Apr 19, 2004 at 06:14 PM.
Apr 19, 2004, 06:40 PM
Crash Master
Gene Bond's Avatar
I'd definately put a cone in front and behind the motor, but I bet it's not that much being blocked, since mose of the motion is on the outer 50% or so of the blades. But, I bet you could easily pick up 15-20%...
Apr 19, 2004, 07:46 PM
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Fishnut's Avatar
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Quote:
Originally Posted by Thatovalguy
To bad the motor blocks the fans outlet or it would have even more thrust. Maybe you could build a shroud to smooth the air flow past it. Its got to be like blowing on a brick wall. Still its got to be WAY better than these stock motors.

papasmurf, 340's is the ticket for the F-16. I do fly once in a while using a 600 but it really only flys, not to pepie.
Guys:

I just switched from the 25 turn stator (37K RPM) to a 20 turn one and now I'm at 44K RPM. Thrust is now well over 1:1 and this thing is a leaf blower.

I made a longer motor mount, hoping it would open up more of the exhaust area by scooting the motor back an inch. Won't really know how effective it is till I get a good scale to measure thrust. BTW: This new motor NEEDS to be in the blast as it's at 96 watts WOT!

Oh I didn't mention in the original post but I finished out the flight mostly at WOT to get a feel for the heat. The battery was luke warm and the motor was stone cold.

I can make a cone for the front, but the back would be problematic, as everything is spinning back there. The things I've read (I made the fan AND THEN discovered the Jets forum) says I should restrict the exhaust area ~10% with a cone.

Anyways, I have created quite a beast and look forward to making many more of different sizes--both fan and stator size.

Kurt
Last edited by Fishnut; Apr 19, 2004 at 08:13 PM.
Apr 20, 2004, 01:28 AM
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Fishnut's Avatar
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Well I just flew it with the 44k RPM motor. Holy $&^%! The sucker is even faster, and it was a challenge keeping it in a lighted ball field. This motor on a real flat wing aerobat will be nothing short of spectacular.

I barely averted disaster when I did a hand release launch. While the thrust is greater than 1:1, the fan is in the center of the bird and it didn't perform anything like a tractor plane. Oh well saved it and learned a lesson. I'll toss it next time.

I just ordered a few of each size. Would anyone be interested in buying the hopped up EDF50s?

Not looking to get rich, just help pay for my habit .

Kurt
Apr 20, 2004, 04:09 PM
"I passed on the kool-aid"

I think many peopel would be interested if the peformance was proven


and the price is within reach. Being that these do not have a "name" attached to them may make some people hesitant to purchase because an individual cannot warrant something like a large company so I think you would have to undercut most of the other brushless offerings significantly to make it feasible. Just my 2Ę. I for one might be interested. Keep us posted on your progress!


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