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Old Dec 24, 2011, 01:50 PM
Registered User
United States, MD, Clinton
Joined Oct 2010
1,002 Posts
I've started to see why people like this jet! It cuts through the wind like a knife in butter too. Gonna need a better battery as the power setup is an amp hog!
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Old Dec 25, 2011, 06:20 PM
Registered User
United Kingdom, England, Prees Higher Heath
Joined Nov 2011
2 Posts
has anyone ever tried the HK2839 EDF Outrunner 2800kv for 70mm fans in one of these, i did a couple of quick tests today with a 6x5 prop 40a esc and 2200 3s 25c lipo, pulling about 390 watts 42amp static i know its pushing the 40a esc but should unload a bit in flight !, not sure about rpm or thrust yet (still to test) i know it's not going ballistic on this but will it work?, all up weight will be down to about 750 -760 grams against the 875 standard auw, i will try and bolt it in tommorow and get some rpm and thrust figures
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Old Dec 25, 2011, 06:43 PM
"Every boy has a dream to fly"
Airplanekid333's Avatar
Fort Collins Colorado
Joined Sep 2009
510 Posts
Just did my maiden voyage flight at sunset, this thing is a FUN jet! extremely fast, didn't need to WOT all the time, flies slow and flares good for landings. It is hard to recover from the torque roll on hand launch. Merry Christmas
Shelby
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Old Dec 25, 2011, 07:50 PM
Why the dirt on the wings?
moparmyway's Avatar
New York
Joined Jan 2009
4,999 Posts
Shelby,
Congrats on your maiden.
There are a few things you could try to alleviate that torque roll

1. Move CG back about 1 or 2 mm
2. Launch with just enough throttle to make the FJ/FJU want to lift off, not full throttle.
3. Launch like you are throwing a "Hail Mary" or bomb pass in football, aim @ 11-12 O'Clock.
4. Look at the following video, you can also use the torque roll to your advantage.
FJ Ultra MEGA 16 35 2 6s2650 5 5x5 5 (2 min 51 sec)
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Old Dec 25, 2011, 09:15 PM
Registered User
Hungary, Borsod-Aba˙j-ZemplÚn, Miskolc
Joined Mar 2011
165 Posts
andy2001 I have a 2836 3500KV outrunner and I'll try it sometime in the future, but the current inrunner 2700KV is performing great. I think the 6x5 is a bit over the top, try 5.5x4.5 or 5x5 for better rpm. It will still climb great, but it won't fry your motor or esc.
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Old Dec 26, 2011, 09:26 AM
"The Judge"
sebbe's Avatar
Sweden
Joined Feb 2006
5,817 Posts
moparmyway , you seem to have about the same setup/propp as in My Ultra , in your video, but I dont get that torque roll at all, I lanch the way you say, I have my CG the way you say, I give it throttle as much as you say, BUT I dont get that torqueroll AT ALL ?? yours is rolling 10 times as much as mine does.. why ?

Do I throw much harder / straighter ?
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Old Dec 26, 2011, 10:00 AM
186mph Funjet Ultra
E-speed buff's Avatar
nieuw vennep, the netherlands
Joined Feb 2010
513 Posts
Hi mopar!

Nice echo

Grtz RenÚ
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Old Dec 26, 2011, 12:09 PM
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United States, NJ, Roseland
Joined Apr 2009
2,214 Posts
Sebbe, Mopar may have had a little wind in his video. i follow the same proceedure as you both and i get no torque roll at all on windless days. Some roll on days with some wind. Better than 1:1 throttle launch 11-12:00 and your golden : )
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Old Dec 26, 2011, 12:45 PM
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restlessswind's Avatar
United States, CA, Sacramento
Joined Jan 2010
3,035 Posts
Quote:
Originally Posted by andy2001 View Post
has anyone ever tried the HK2839 EDF Outrunner 2800kv for 70mm fans in one of these, i did a couple of quick tests today with a 6x5 prop 40a esc and 2200 3s 25c lipo, pulling about 390 watts 42amp static i know its pushing the 40a esc but should unload a bit in flight !, not sure about rpm or thrust yet (still to test) i know it's not going ballistic on this but will it work?, all up weight will be down to about 750 -760 grams against the 875 standard auw, i will try and bolt it in tommorow and get some rpm and thrust figures
Generally, EDF motors can be pushed a little harder than their ratings in a pusher due to the better airflow (Edf motors are usually trapped in a plastic housing with limited airflow). So this 2700kv motor should be ok up to 50 or 60 amps (burst) Maybe more, maybe less. It's really all about what you are comfortable with. If you run the motor for 4-5 seconds and it is quite hot to the touch, I would use a smaller prop (or 1 less cell) until I get maximum desired results
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Old Dec 26, 2011, 01:25 PM
"Every boy has a dream to fly"
Airplanekid333's Avatar
Fort Collins Colorado
Joined Sep 2009
510 Posts
Tried to have my second flight today, but the torque roll sent me to the ground, thank goodness for snow that reduced the damage. My mistake was I hand launched it about 45 degrees outwards instead of straight up like i did on my maiden.
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Old Dec 26, 2011, 01:54 PM
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GryphonRCU's Avatar
United States, CA, SF
Joined Mar 2008
3,865 Posts
Mopar,

Nice video.

I think I have seen one of your videos with a bigger prop on same motor.

I know, it is not like max props should be run all the time, but I was wondering if you were experimenting as always.


Gryphon
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Old Dec 26, 2011, 03:02 PM
Why the dirt on the wings?
moparmyway's Avatar
New York
Joined Jan 2009
4,999 Posts
Quote:
Originally Posted by sebbe View Post
moparmyway , you seem to have about the same setup/propp as in My Ultra , in your video, but I dont get that torque roll at all, I lanch the way you say, I have my CG the way you say, I give it throttle as much as you say, BUT I dont get that torqueroll AT ALL ?? yours is rolling 10 times as much as mine does.. why ?

Do I throw much harder / straighter ?
I think its the throw, I rountinely throw 5 pound Strykers straight up, and I throw my FJU the same way. It doesnt matter if there is any wind or not, I get torque roll every time. I also run my CG just a hair nose heavy, less twitchy in the air this way for me.

I allways suggest a slight rearward CG to alleviate torque roll, but I dont find it necessary to do so for myself cause I can throw it pretty good straight up.
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Old Dec 26, 2011, 03:05 PM
Why the dirt on the wings?
moparmyway's Avatar
New York
Joined Jan 2009
4,999 Posts
Quote:
Originally Posted by E-speed buff View Post
Hi mopar!

Nice echo

Grtz RenÚ
Yo Dude !!
I aint too sure which echo you are speaking of ............
The one from the tower, or the one from the prop.
That tower has to go !!!!!
Its in the way for max speed runs, but I also notice an echo (more resonance) from the Graupner 5.5x5.5 prop. Its only there for a few seconds, then when she picks up some speed, it goes away.
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Old Dec 26, 2011, 03:10 PM
Why the dirt on the wings?
moparmyway's Avatar
New York
Joined Jan 2009
4,999 Posts
Quote:
Originally Posted by GryphonRCU View Post
Mopar,

Nice video.

I think I have seen one of your videos with a bigger prop on same motor.

I know, it is not like max props should be run all the time, but I was wondering if you were experimenting as always.


Gryphon
I was going for run-time on that setup.
With 6s2650 batts, the 16-35-2 was under so little stress with the Graupner 5.5x5.5 that I can get about 7 minutes in the air and lay down some 150 mph passes, and the MEGA came down with icicles on it.

I believe someone has run the 6x4 Sport with 8 cells and that motor, so if anyone is looking for an absolute blast, long run time, daily flying speedster with room to expand, the 16-35-2 is one fine choice.
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Old Dec 26, 2011, 05:28 PM
186mph Funjet Ultra
E-speed buff's Avatar
nieuw vennep, the netherlands
Joined Feb 2010
513 Posts
Hi mopar!

I ment the prop sound reverberating from the tree line.

Grtz RenÚ
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