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Teksumo Speed fluttering

#1
So I've had the Teksumo for a while now but on the maiden flight I got some serious speed fluttering of the elevens which eventuates in the wing splitting itself apart down the middle, in midair. I repaired it and it flies but I just can go fast now otherwise it flutters again. In the FliteTest episode they're going 70mph and I can even get above half throttle unless I'm climbing. Has anyone got a fix for this problem because I'm stumped.
 
#2
It's probably worth checking your hinges first to see if they are completely intact. Then you could put some CF strip in the elevons to stiffen them up ... should solve your problem
 

lobstermash

Propaganda machine
Mentor
#3
More cf reinforcement, and make sure that the current reinforcement isn't able to move horizontally (got the same but worse problem with my Red Eagle wing)
 

earthsciteach

Moderator
Moderator
#4
My Assassin wing was doing the same thing. I pulled all the laminate/tape off (shocked by the weight of tape I had slapped on it). The carbon fiber spar was loose from the foam as per lobster's comment. She's much stiffer now!

If you haven't, get some lamination sheeting and cover the wing. Just iron it on. It does wonders for stiffening the foam!
 
#5
Well both elevens come with a thick carbon fibre tube in them and the hinges are intact so I'm not sure what to do, maybe get stronger servos?
 

jetpackninja

More combat please...
Mentor
#7
Very likely it's the wing itself that needs braced.
I don't have one of these but it looks to me that there isn't any bracing that spans across the two halves of the wing core.
I would add a CF spar (or spruce or bamboo whatever your choice material is) that spans across the two halves at or near the CG.
Here's a picture of my Assassin. Look at the carbon strip on the bottom of the plane. Also note the extreme tape that is laid on in a cross your heart pattern at the TE and continuing across to keep the two core halves together. Also one strip over the CF spar and over the front to keep the spar from releasing in a crash...
 

PaulT

New member
Mentor
#9
The Tek Sumo has cf rods that join the two halves which I am SURE you installed.
Since you have checked the hinges already, is there ANY play in your servo rods? There shouldn't be.
I get no flutter in mine at all even at WOT.
I would like to see a video of it fluttering. That would be neat!:eek:
 

jetpackninja

More combat please...
Mentor
#10
Here is a pic of a Swift with a spar (I think he added this one, I don't think it came with the kit)

Paul- I'm at work so I cant see your build pictures. Does the Tek Sumo come with a similar spar?

BILD0163-1024x768.jpg
 

PaulT

New member
Mentor
#11
Actually it comes with two spars that need to be installed.
One that goes just behind the battery and one that goes behind the receiver compartments.
Without these I should think you would get too much flex.
I still want to see a video!!!!
 

kaon

Junior Member
#12
Actually it comes with two spars that need to be installed.
One that goes just behind the battery and one that goes behind the receiver compartments.
Without these I should think you would get too much flex.
I still want to see a video!!!!
My TekSumo arrived in early July 2012.
Mine had three (3) (not 2) carbon sticks to be installed. All 3 are the same length. 2 are installed in precut slits on the underside as you described.
The last stick goes into a slit that is cut into the top side of the wing.
I think the color-printed manual I got was quite clear about this.

So, is there more than one version of the Teksumo?

BTW, where's the best CG?
 

PaulT

New member
Mentor
#13
My bad. There are three spars that come with the kit that need to be installed.
I have my cg at 210 mm from the tip which is almost exactly over the bottom rear most spar.
When you do your final set up make sure that your elevons are flexed about
1/4 inch in the up possition. This is where you will get level flight.
If you don't you will nose dive on your launches no matter how you toss it.
:rolleyes: