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Old May 22, 2013, 12:12 PM
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United States, MI, Clio
Joined Mar 2004
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Funjet Ultra Torque Roll

I have a funjet I bought off craigslist the guy clocked it at 169mph. I have flown it three times now and the torque roll on the launch is terrible. Is there anything I can do to help alleviate this problem, other than a smaller motor. Here is the link to my first flight video.

On my second flight I was about treetop level and quarter throttle. Went to WOT and it torque rolled 3 times before I know what happened but ended right side up. It was crazy!!

Motor Turnigy 3648-1400KV
ESC Hobby wing 100a platinum
Bat Turnigy Nanotech 6s 2650

The plane is covered in 10 min finishing epoxy and wieghs in at 4lbs

Any help would be great!

First flight Funjet ultra (1 min 49 sec)
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Last edited by irelandchad; May 22, 2013 at 12:17 PM. Reason: Added set up info
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Old May 22, 2013, 12:24 PM
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Canada, NS, Lunenburg
Joined Oct 1999
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Try launching at half throttle. From idle, always throttle up slowly.
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Old May 22, 2013, 12:26 PM
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United States, MI, Clio
Joined Mar 2004
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The launch in the video was alittle less than half throttle.
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Old May 22, 2013, 12:28 PM
"The Judge"
sebbe's Avatar
Sweden
Joined Feb 2006
5,761 Posts
there is no way to get help , thats how i lost my ultra, this time Im going for bungee start, HK:s blue rubber band they say is allright, take a few steps back and release, and thats enough for the ultra to get airborne and even make a turn before hitting the throttle

I throw hard and straight, didnt help... you have a guy throwing for you, even better, but still its a problem...

anything bigger then 6" prop is a pain and heavy dont help either...

You can throw it straight up, and let the ultra do its thing and just go with it, thats one way..

Dont think you will find a way throwing a 4 lbs ultra with that torque easy way..
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Last edited by sebbe; May 22, 2013 at 12:35 PM.
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Old May 22, 2013, 12:33 PM
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Canada, SK, Prince Albert
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Am curious...what prop?
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Old May 22, 2013, 12:36 PM
"The Judge"
sebbe's Avatar
Sweden
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I would say hes using a 7" prop.
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Old May 22, 2013, 12:42 PM
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United States, MI, Clio
Joined Mar 2004
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7x5 prop. The third flight I had was little better. Diffrent guy throwing lots of right stick and a low right wing throw. But it still scared the crap out of me!!.
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Old May 22, 2013, 01:40 PM
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I'm not sure the rubber band would work w/6s.

Haven't seen it so can't say for certain but just yesterday tried the latex tubing, which launches a 4s 3300 FJU just fine, and it couldn't get enough pull to get the 6s one moving fast enough to use the elevons. Lot of variables so only someone who's done it w/6s can say for certain..
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Old May 22, 2013, 01:51 PM
"The Judge"
sebbe's Avatar
Sweden
Joined Feb 2006
5,761 Posts
stanordave , the ultra with the hk 1900kv and 6s 2700mah is just fine with that HK blue rubber. its confirmed but at least one guy,,, thats why I bought it.

It was he who said it will go up and make turn before you have to hit the throttle.. he said you have to make it 2 way, spilt the blue rubber in 2 pieces, put them together. perfect..

Sebbe
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Old May 22, 2013, 03:27 PM
What is Highspeed ?
Rolf D.'s Avatar
Germany, BY, Bergen
Joined Feb 2011
512 Posts
Oh Boys
the Problem where the "half" torque roll Comes from is very good to see in the Video.
Motor ON:
and at the same Moment the guy throws the FJ out !

Point is - he did not wait for a Moment that the Propeller has grip.
so what happens ? easy : prop no grip : flow demolution - flow demolution what happens by it ?? YES - Plane like a funjet goes starting to torque !
when in the torque roll Propeller gets grip and it that Moment the Motor in the bird has enough power to bring him Forward.

so next time - throttle of, wait a Moment ( I know the dude´s who throw it feel scary from the noise ) and than start like it has to bee

regards
Rolf
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Old May 22, 2013, 03:43 PM
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Thanks Sebbe! Gonna order one now!

[edit] not gonna order one now..out of stock!
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Last edited by stanordave; May 22, 2013 at 03:54 PM.
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Old May 22, 2013, 03:53 PM
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Germany
Joined Jul 2010
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Why would waiting help the prop develop "grip"? Maybe you should do a burnout at full throttle which heats up the air and the prop and thus gives you more grip like in drag racing!

No seriously, launch with enough power for the plane to accelerate safely, if you have better than 1:1 thrust to weight a steep launch is a good way to give it more room to do its thing without crashing. Don't throttle up immediately after launch because at low speed the inertia of the outrunner can accelerating and of course the torque will flip the plane over. Once you have some airspeed you can smoothly push up the power.

Edit: I've looked up 'demolution' it seems like that's a rock band from holland?
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Old May 22, 2013, 03:58 PM
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United States, TX, Friendswood
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Try using reflex on takeoff. I use the speedbrake option on my futaba 7c for takeoff. I flip a switch to put the ailerons up a little bit and give a good throw with 1/2 throttle (hit the switch to neutralize the controls shortly after takeoff). Not sure if this will help your torque rolls on takeoff but it makes takeoff much easier
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Old May 22, 2013, 04:00 PM
What is Highspeed ?
Rolf D.'s Avatar
Germany, BY, Bergen
Joined Feb 2011
512 Posts
Quote:
Originally Posted by Kwahn View Post
Why would waiting help the prop develop "grip"? Maybe you should do a burnout at full throttle which heats up the air and the prop and thus gives you more grip like in drag racing!

Edit: I've looked up 'demolution' it seems like that's a rock band from holland?
I do not mean with FULL THROTTLE

demolution was the Little devil in my Keyboard ;-) means flow demolition
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Old May 22, 2013, 04:09 PM
2012 NZ Speedcup - 231 MPH
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New Zealand, Tasman, Richmond
Joined Mar 2006
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Prop down to 6" (say a 6x6)... A 7" prop is almost 25% of the wingspan.
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