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Solved Ft Guinea Twin Uneven Thrust

#1
Hello,
This winter I built a Guinea twin and tried to set it up without differential thrust; however, when I went to throttle up one of the motors spun faster than the other somewhat considerably. Both ESCs(from the twin power pack C) are plugged into the same channel on my radio(FLYSKY FS-i6X) with a y harness and they are both powered with the same battery through a Y harness so they should be getting the same voltage. Would anybody know what might be causing this because I'm completely lost. Any help would be wonderful as I can't wait to get it into the air!
 
#3
Thank you! I'll try that in a bit but do you know if the flite test ESCs have instructions online somewhere on how to do that because they didn't come with any.
 
#4
Thank you! I'll try that in a bit but do you know if the flite test ESCs have instructions online somewhere on how to do that because they didn't come with any.
Remove the props for safety!
With the plane off and the transmitter on, set throttle to maximum
Power on the plane. The ESCs will do their usual power-on tone followed by a few beeps
When the beeps stop, move the throttle to minimum
The ESCs should beep again and return to their usual functionality, now with the throttle ranges calibrated.

It's not necessary to calibrate each ESC individually - in fact, you've got a better shot doing both at once since both ESCs will be seeing the exact same signal.
 
#5
Yeah, my first instinct was to say calibrate ESCs. Double check to ensure both motor KV are the same too. I flew one plane with a 2700 kv on one side and a 2100kv on the other and it was fun! It wasn't that terrible, but it caused the issue you describe. The motors looked the same, but they weren't!
 

WillL84

Active member
#7
Remove the props for safety!
With the plane off and the transmitter on, set throttle to maximum
Power on the plane. The ESCs will do their usual power-on tone followed by a few beeps
When the beeps stop, move the throttle to minimum
The ESCs should beep again and return to their usual functionality, now with the throttle ranges calibrated.

It's not necessary to calibrate each ESC individually - in fact, you've got a better shot doing both at once since both ESCs will be seeing the exact same signal.
Thanks for this, need to do this on my Legacy. Shame there was no mention of this in the build videos
 
#8
Sorry to drag up an old thread with a noob question.

I built a delta wing / ultrix style frame, matched esc’s and motors with both esc’s connected to 1 battery, in theory to prevent one battery dropping voltage quicker than the other.

The left motor must have been spinning faster than the right as it would immediately bank right.

I used esc’s from eBay, CW and CCW motors from hobbyking.

Would the procedure described above work for all esc’s or only the FT ones?


Edit, I’ve done a bench set up/ test, the esc’s seemed to calibrate, but haven’t tested with props on,
 
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#10
Sorry to drag up an old thread with a noob question.

I built a delta wing / ultrix style frame, matched esc’s and motors with both esc’s connected to 1 battery, in theory to prevent one battery dropping voltage quicker than the other.

The left motor must have been spinning faster than the right as it would immediately bank right.

I used esc’s from eBay, CW and CCW motors from hobbyking.

Would the procedure described above work for all esc’s or only the FT ones?


Edit, I’ve done a bench set up/ test, the esc’s seemed to calibrate, but haven’t tested with props on,
Calibrate the ESCs. Turn on your transmitter, push throttle all the way up. Plug in your LIPO into your ESCs. Waits for the start up tones from both ESCs - then bring your throttle to zero. See if that makes the motors run in sync with props on.
 

Piotrsko

Master member
#11
Are the motors turning the same direction? Are you advancing throttle to max then immediately throwing it? Have you test glided it to check trim? 3 of many reasons why it turns right.
 
#12
No the motors turn counter to each other, CW and CCW. With CW and CCW props

I tried throwing / launching it as different throttle speeds. The higher the speed the quicker it would turn.

I have since converted it to a single motor to see if I can get it to fly .

The control surfaces were a little small, I doubled them in size, but as I’ve build without plans it’s trial and error to get the CG right.

Plus finding the right prop size, with an 8” it tends to loop backwards very quickly with a small increase of throttle when trying to get it to stay in the air.

I only had a 6” to try, it didn’t have enough thrust to sustain flight.

I’ve got some different size/pitch/blade count coming. I’ll have to trial a few different set ups to find what works best with it.
 
#14
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This was version 1 as it were with the twin motor set up. One of the only photos I have of it. I’ll have to take some of it as version 2 with the single motor set up.
 
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#15
Here are some photos of version 2, I added a vertical stabiliser, trimmed the rear of the wings and assed the removed material to the tips of the wings,

I modified the fuselage to strengthen it and reduce a little weight and the need for struts as it were under the wings.

You may be able to see the join in the elevons where I increased their size,

8D1E8973-FE8E-47FF-B1DE-907662385CB2.jpeg
04D4E814-221D-4AB1-ADBE-718F6E37DC02.jpeg
7AF454F5-F613-414F-B3C7-DC1AD403A559.jpeg
58089974-9DF3-4661-896C-7031415F2BB5.jpeg
D3D9A761-D51C-405E-B71E-6FC028CAC317.jpeg
 
#16
Pictures show it should turn left from the misalignments, your newest prop size comment makes me think CG is too far aft. By any chance is the CG further back than 1/3 span ( or 1 1/2" in front of what looks to be a spar) or about where the grey thing is sitting in the last picture? And do you have down and right thrust?
 
#17
In the last photo, it looks like the wing tip is curved upwards.

My question to you is, Are both sides symmetrical?
Also, if you try balancing the nose-tail axis , Is one wing tip dropping down(heavier) ?
Only other choice is add a servo and when chucking, use the moving rudder to compensate.
 
#18
C
Pictures show it should turn left from the misalignments, your newest prop size comment makes me think CG is too far aft. By any chance is the CG further back than 1/3 span ( or 1 1/2" in front of what looks to be a spar) or about where the grey thing is sitting in the last picture? And do you have down and right thrust?
CG was roughly at where the spar is, 1/3 from the front. I made it so I can move the battery around to get CG.

The prop is a reverse rotation , so I’ve set down and left thrust. ( when stating clock wise or counter clock wise I’m not sure if it’s when looking at the plane front on or if as sitting in the cockpit looking forward) so looking at it like you’re in the cockpit it’s CCW/ reverse to all the factory planes I have.

The idea of the fuselage in version 1 was to have a pendulum effect by having the battery down low and an open channel so the receiver and battery could be placed to achieve CD by trial and error as it we as I built from no plans so CG had to be determined by moving the battery until it it was found then having Velcro in that place but with the ability to adjust it slightly after trial flight to get it optimal.
 
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#19
It
In the last photo, it looks like the wing tip is curved upwards.

My question to you is, Are both sides symmetrical?
Also, if you try balancing the nose-tail axis , Is one wing tip dropping down(heavier) ?
Only other choice is add a servo and when chucking, use the moving rudder to compensate.
It’s as symmetrical as I could get it with measurements .

The idea of the wings was to incorporate a poly dihedral design .

No I haven’t determined if it’s balanced across the wing span. I figured the wing cord depth and span would allow for small discrepancies in weight/ size .

I’m convinced the aggressive yaw was due to one motor revving harder than the other, as I hadn’t calibrated them, I had no idea about calibrating them as simply as they could be.

I converted it to a single motor before I learned this, to see if it would actually fly, which I’d has a little, but I think my control surfaces were too small as it didn’t react to the inputs on them much at all to turn, but elevators worked well, just turning/banking didn’t do much at all, hence doubling their size.

Big thanks to this forum/ thread and the awesome members and replies I learned how to do that.

One of the local club members has an optical tacho, I’ll set up a bench test with the twin motor set up and props and see if they are actually matched after calibrating the esc’s.