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Author Topic: E-Vector 40 trimming  (Read 2153 times)

Offline Bogdan Birsan

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E-Vector 40 trimming
« on: June 11, 2022, 09:38:41 AM »
Dear Stunt Community,

I recently acquired an E-Vector 40 ARF, assembled it and equipped it as listed below.

Motor: AXI 2826/12
Prop: Brodak 11.6x5 Pusher cut-down from a 12x5
ESC: Castle Phoenix Edge 50, high governor mode, 45 governor gain, 10 head speed change rate
Timer: Home made
Battery: GensAce 5S 2200mAh (haven't done a full pattern yet so don't know if 2200 will suffice)

Motor out-thrust: 1.5 degrees
Rudder offset: 0
CG: 175mm from flaps hinge line
LO: 17mm back from CG (line III proposes 20mm)
Tip weight: 28 gr
Weight: 1450 gr
Lines: 18.8 meters
RPM: 9400
Lap time: 4.95 sec

The model is still in trimming but I have reached a dead-end and would need your help in order to be able to continue. I am having a problem with line tension overhead and don't know how to improve it. I am flying 4.95 sec/lap with LO quite forward in an effort to obtain good tension overhead but without a satisfying result. I am afraid to push the LO even more forward since in the listed setups here no-one flies with them as forward as I.

My last ace in the sleeve would be to play with the rudder offset. However, having an IC background, I understand that if I use pusher props rudder offset wouldn't be needed.

So far I used the trimming chart from flying lines. So I have level wings both upright and inverted, I am comfortable with my pitch sensitivity and there is not hinging exiting a normal wingover at 45 degrees height. Would you guys have any ideas what else I can try in order to improve tension overhead ?

Thanks in advance


Online Dennis Nunes

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Re: E-Vector 40 trimming
« Reply #1 on: June 11, 2022, 09:56:13 AM »
The model is still in trimming but I have reached a dead-end and would need your help in order to be able to continue. I am having a problem with line tension overhead and don't know how to improve it. I am flying 4.95 sec/lap with LO quite forward in an effort to obtain good tension overhead but without a satisfying result. I am afraid to push the LO even more forward since in the listed setups here no-one flies with them as forward as I.

My last ace in the sleeve would be to play with the rudder offset. However, having an IC background, I understand that if I use pusher props rudder offset wouldn't be needed.

So far I used the trimming chart from flying lines. So I have level wings both upright and inverted, I am comfortable with my pitch sensitivity and there is not hinging exiting a normal wingover at 45 degrees height. Would you guys have any ideas what else I can try in order to improve tension overhead ?

Hi Bogdan,
I'm NOT running a pusher prop. However, I would first suggest adding more motor offset. I run my electrics with 2.5 degrees offset. Second, your leadout position appears to be too far forward. Both of my electric planes are between 1.5" (38mm) and 1.375" (35mm) behind the C/G. Try the motor offset first. Then adjust the leadout and/or tip weight until the plane begins to "hinge" in corners, then back off. BTW, none of my planes use rudder offset. Hope this helps.

Dennis
« Last Edit: June 11, 2022, 10:16:02 AM by Dennis Nunes »

Offline Motorman

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Re: E-Vector 40 trimming
« Reply #2 on: June 11, 2022, 10:28:44 AM »
Are you an advanced flyer? You have to keep your stunts smooth to keep your speed up. Some props don't pull good up top. Might want to try something with less pitch at the tips or get a nice CF 3 blade.

Motorman 8)

Offline Massimo Rimoldi

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Re: E-Vector 40 trimming
« Reply #3 on: June 11, 2022, 01:45:52 PM »
Hello.
  In the conventional management of our models the line tension is essentially entrusted to the centrifugal force and in this case the data you provide seem to indicate that this is sufficient for the purpose.
  If the tension is insufficient during the maneuvers, the cases are:
  1) the speed decreases and with it the centrifugal force
  2) a part of the lift or in any case of the forces produced during the maneuver is directed towards the center of the circle.
  A model with the LO too far back flies skidded and when the wing rotates during maneuvers some of the lift is directed into the flight hemisphere.
  So if the speed is more or less constant and the LO are not too far back I think the cause is some warping or misalignment.
Check the tip weight, Check that the model flies with the horizontal wing in straight and inverted flight, that the hinge line of the flaps is parallel to that of the tail plane etc.
  Good luck and keep us informed of developments

Massimo

P.S.: I don't think playing with the rudder ofset is a good idea (the deflection usually necessary is very small and in any case does not bring a significant increase in tension), the result is like the LO too far behind,
« Last Edit: June 11, 2022, 04:03:49 PM by Massimo Rimoldi »

Online Ken Culbertson

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Re: E-Vector 40 trimming
« Reply #4 on: June 11, 2022, 10:35:17 PM »
Dear Stunt Community,

I recently acquired an E-Vector 40 ARF, assembled it and equipped it as listed below.

Motor: AXI 2826/12
Prop: Brodak 11.6x5 Pusher cut-down from a 12x5
ESC: Castle Phoenix Edge 50, high governor mode, 45 governor gain, 10 head speed change rate
Timer: Home made
Battery: GensAce 5S 2200mAh (haven't done a full pattern yet so don't know if 2200 will suffice)

Motor out-thrust: 1.5 degrees
Rudder offset: 0
CG: 175mm from flaps hinge line
LO: 17mm back from CG (line III proposes 20mm)
Tip weight: 28 gr
Weight: 1450 gr
Lines: 18.8 meters
RPM: 9400
Lap time: 4.95 sec

The model is still in trimming but I have reached a dead-end and would need your help in order to be able to continue. I am having a problem with line tension overhead and don't know how to improve it. I am flying 4.95 sec/lap with LO quite forward in an effort to obtain good tension overhead but without a satisfying result. I am afraid to push the LO even more forward since in the listed setups here no-one flies with them as forward as I.

My last ace in the sleeve would be to play with the rudder offset. However, having an IC background, I understand that if I use pusher props rudder offset wouldn't be needed.

So far I used the trimming chart from flying lines. So I have level wings both upright and inverted, I am comfortable with my pitch sensitivity and there is not hinging exiting a normal wingover at 45 degrees height. Would you guys have any ideas what else I can try in order to improve tension overhead ?

Thanks in advance


I flew a borrowed E-Vector 40 ARF for the better part of a year after losing my fleet in a fire.  It is a fine plane and should behave better.  Some differences I noticed in yours.  I carried 1 1/2 ounces of tip weight and my CG was a bit more towards the nose.  My leadouts were 1/4" behind the CG.  No Rudder offset but I did have 2 degrees motor offset.  I flew it pusher on .015 lines using a FM-9 timer.  One difference was line length.  I flew on 63' at 5.1.   The plane does not like to fly slow so keeping the momentum up is critical.  You have to fly corners.  You can do them tight and still keep momentum.  If you hit them too hard it will be like a rag doll at the end of the sq8.  Is it possible that your timer is not keeping up?  I have switched to an active timer so fixing overhead tension is much simpler since the boost keeps your momentum up.

One thing that has already been mentioned.  If the wing and stab hinge lines are not 100%, well at least 99%, parallel the plane can lose tension when you give it control. 

My guess - tip weight.

Ken

Almost forgot, I was able to get full patterns on a 4s 2200 using that same ESC, a 2820/12 Cobra motor using an 11x5.5 prop at 9600 rpm.  It was tight and I could feel a slight loss of power in the clover.  16% left which is really low. The 5s should do just fine.
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Offline Dennis Toth

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Re: E-Vector 40 trimming
« Reply #5 on: June 12, 2022, 06:15:48 AM »
 Bodgan,
I looks like you are in the range for al the normal trim features. You indicated the timers was you own, this may be the key to holding the speed up top. I use the timer to control only the flight time. I use the ESC to control the rpm in control line mode, Fixed RPM. I had an issue with the timer at one point holding back the rpm until I reset all the throttle point to 100% and let the ESC to the rpm control.

Two other points, pushing the leadouts to far forward will increase tension in level flight but decrease up top. Make small 1/8" rearward adjustments until it starts losing tension up top to fine the sweet spot. Second, you might be better off with a prop with a bit wider tip cord or more pitch in the last 25% of the blades. Many props decrease the tip pitch but have slightly increased tip pitch give more pulling power for us. Square tips give more tension and pull if you have the battery capacity, which the 5S will give you. Try cutting a 13" down to the 11.5 or use the full 12" diameter with the tips pitched up 2% more then the pitch at the 70% station.

Let us know your progress.

Best,   DennisT

Teodorico Terry

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Re: E-Vector 40 trimming
« Reply #6 on: June 12, 2022, 06:12:14 PM »
On one of my models I discovered accidentally that moving the C.G. forward improved line tension.  As originally set-up the CG was just slightly forward of the bellcrank's pivot point and shifting the CG another 5-6 mm or so forward helped. The other change that helped was reducing the rudder offset.  This particular model has a longish fuselage which might have amplified the effect of rudder offset. In its current configuration the fuselage is closer to being tangent to the circle; I suspect that in flight the model generates less drag which results in less speed being lost when maneuvering in the vertical.  My lap times are in the 5.3 second range so I am not flying blazingly fast either.

The ESC you are using allows for data logging and it might make sense to take a look at the currents while in flight.  You can make adjustments to the ESC which will allow it to respond more quickly to changes in load thus keeping a more constant RPM.  On my 40 sized Legacy, its base power in level flight is of about 420 watts going up to around 550 watts when maneuvering.  This is on a 6S set-up so the currents are not crazy high.  At any rate, looking at the logged data allowed me to see what effect changes in the ESC settings had on performance.

Good luck,

Teo

Offline Bogdan Birsan

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Re: E-Vector 40 trimming
« Reply #7 on: June 13, 2022, 12:09:28 PM »
Motorman,
I am intermediate flyer as I have done only junior patern so far (round outside loop, inverted flight, wingover, horizontal eight) plus some senior pattern figures (round inside loops, vertical eight) with my IC engine stunter. However passing to the e-vector 40 I struggle even with the round loops (at the point that I have to step back in the first loop) so I don't think there is a finesse problem here.

Massimo,
Indeed I found a warp in one of the wings and flap, even if for me the plane was flying with wings level both upright and inverted. So I corrected the warps and I feel a small improvement. That, together with leadouts 5 mm barckwards (so now at 22mm behind CG) generates acceptable tension in the wingover. I checked hingelines and every other parallelism and all seems good to me.

Ken,
LO 0.25 inch back from CG ? Are you sure? Not rather 1.25 inches ? And CG position shouldn't affect line tension, only pitch sensitivity, so if yours had the CG a little more forward it should only be less sensitive to pitch commands compared to mine.


Denis,
I measured the timer output signal with an oscilloscope (I'm an electronics engineer) so I am sure that the signal is steady. The ESC receives the same throttle input no matter the position of the plane so I highly doubt that it is loosing RPM overhead. Besides, I checked the logged RPM of the ESC and it is quite constant (only a small drop of 50 RPM when entering the figures). I tried pushing the LO even more towards the rear but it begins to loose tension in the wingover. So I will try adding more tip weight first, see if the round loops improve and then retry moving the LO more aft. I will also try a cut down 13x5 to 12x5 but I don't think it will do miracles (fingers crossed).


Teo,
The governor gain is set at a custom 45 even higher than the 'high' settings of the ESC which is 35. I honestly am surprised that the RPM doesn't oscillate. So to be completely honest I doubt that the problem comes from loosing RPM.

I attached the data of the ESC. Let me know if you I missed something and you manage to see something suspicious.
Do you guys know if moving the LO aft requires more tip weight ?
Also, do you know how to reduce hinging due to the wind ? When I fly in the wind the plane rolls towards the inside a little each time the wind hits it laterally.


Offline Massimo Rimoldi

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Re: E-Vector 40 trimming
« Reply #8 on: June 13, 2022, 01:40:11 PM »
Hi.
Ask someone you trust to check the position of the wings by looking from the outside of the circle, it is difficult to see accurately as you fly.  With the model hanging on the LOs, check that the vertical position of the center of gravity is aligned with the LO output.  Try adding a few grams to the tip weight, however always only make a small change at a time and maybe more than one test flight before deciding if the change was useful.

Massimo

Offline Tim Wescott

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Re: E-Vector 40 trimming
« Reply #9 on: June 13, 2022, 02:08:56 PM »
Two folks have already said this, but it bears repeating: your leadouts may be too far forward.

There's an optimal leadout position.  Getting too far forward of it, or too far back will result in loss of line tension in the overheads.  And, as mentioned, a bit more tip weight may help (although it's really easy to go overboard on that -- adding too much tip weight is the second-easiest way to paper over other trim problems, right after a too-fast airplane speed).

Paul Walker's trim chart is on the web in more than one spot -- I just gave you a link to my favorite spot.  It's not hard to follow the first part of it; getting deeper into it demands more of your ability to tell what the plane is doing, but it's worthwhile.  Just follow along as best as you can, and see if your performance improves.
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Online Ken Culbertson

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Re: E-Vector 40 trimming
« Reply #10 on: June 13, 2022, 04:00:08 PM »
Ken,
LO 0.25 inch back from CG ? Are you sure? Not rather 1.25 inches ? And CG position shouldn't affect line tension, only pitch sensitivity, so if yours had the CG a little more forward it should only be less sensitive to pitch commands compared to mine.
Bogdan, every plane has a sweet spot for the leadouts.  My flying style has the leadouts somewhat further forward from the "standard".   1 1/2" behind the CG would be way out of my comfort zone.  On a new ship I set them at 3/4" behind.  I have had some where I had them on or even slightly ahead of the CG.  It depends totally what the plane wants and how you fly it.  A lot of fliers will move them back in wind to help keep upwind tension.  I go forward to ease downwind tension.  It is all a matter of style.  As you get better, and you will, try and learn to listen to the plane.  I wish there was a way to teach that but there isn't.  You just have to acquire it, and you will.

CG definitely does affect line tension as well as sensativity.  However, sensativity is relative to a lot of other things that can be changed.  For example, moving the cg forward some will not change your corner radius.  It will change the amount of control that you give it but that is all subconscious, it just happens.  That is why so many fliers use nose weight to mask all kinds of trim problems.

While we are on nose weight, one of the "advantages" of electric is the constant CG.  With IC you get more and more tail heavy as the tank drains.  This results in less tension and more sensativity  in the last half of the pattern starting with the vertical 8.  Some see that as an advantage, I don't. 

Ken
« Last Edit: June 13, 2022, 04:29:42 PM by Ken Culbertson »
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Offline Bogdan Birsan

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Re: E-Vector 40 trimming
« Reply #11 on: June 29, 2022, 12:34:38 PM »
Dear Stunt Community,

Thank you for your answers. I am writing again to share my progress.

I have managed to finally settle on LO position and TW so I now have acceptable line tension everywhere in the round loops, wing over, horizontal 8 and inside square loops. However, I still not comfortable with outside squares and hourglass as I am loosing significant tension when hitting the down command. Since I have checked level wings (using a camera by the way), wing and stabilizer parallelness in both horizontal and vertical planes, my only leads remain adding rabe rudder or decreasing the size of the propeller. I like my 11.5x5 wooden prop because it gives good tension in wingover so I am rather inclined to use rabe rudder.

So I would like to get your opinion on choosing the hinge line of the future rudder. I attached a picture with the hingeline I am thinking on doing but I am having second thoughts because I am affraid that the big imbalance between the upper surface of the moving part and the lower surface of the moving part might cause too much roll when rudder is applied ? What do you think that my hesitations are founded ?

Regards,
Bogdan

Offline pmackenzie

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Re: E-Vector 40 trimming
« Reply #12 on: June 29, 2022, 04:36:13 PM »
Here is how I did the Rabe rudder on my Vector 40.

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Offline TDM

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Re: E-Vector 40 trimming
« Reply #13 on: June 29, 2022, 05:13:19 PM »
Probably a lead out location issue not a motor run issue. I am guessing at 5.1 5.2s per lap it should go anywhere with a good setup. It sounds like you have a nice setup and you can adjust to get whatever lap time you want.

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Offline Bogdan Birsan

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Re: E-Vector 40 trimming
« Reply #14 on: June 30, 2022, 02:53:12 AM »
Pat,
Could you be so kind to send me a photo of the opposite side too so that I can see how you did the hinges ? Also, a photo with elevator down and up viewed from the behind the plane would be welcomed.

TDM,
I tried moving the leadouts without success.

Thanks you guys!


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