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Contra Rotating Propeller Drive for f3a 2m Pattern Planes

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Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Old 12-09-2019, 03:57 PM
  #1926  
PeterP
 
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Hi Jason,

What brand props are you using? It looks like you have a glitter finish on them.

Peter
Old 12-10-2019, 11:34 AM
  #1927  
serious power
 
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Could they be spray painted metalic silver ??

Brian
Old 12-21-2019, 10:53 AM
  #1928  
DaveL322
 
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Originally Posted by Henning View Post
Hi Peter

Are you using a Futaba Tx with the D3? If yes what ATVs are you using? What do you use at landing? Idle-up switch or a different throttle curve? It would be great if you could please share a picture of your throttle curve.


Thanks
Henning
Henning,

I have completed some flights with the V4 and the D3 ESC and the 18SZ transmitter. Falcon 23x20F and 23x22R, Pyro 600-970, Allure @ 4550g with TP5000s.

The endpoints for the throttle are set at 120% on the low (1193us) and 109% on the high (1980us). 114% on the high will show 2000us, but I am using 109% to allow some overhead for the governor to keep the maximum power the same at the end of the flight when the battery voltage has dropped. I tried to make all curves close to the same power with the throttle stick in the middle position, so it is easier to change between curves without causing a sudden change to the motor power.

Takeoff Landing throttle curve
I use a 3 position switch to makes small changes to idle speed on the throttle AFR curve.
990us (zero RPM).
1193us (slow idle). Futaba “rate” on the mixing curve is -65, and this is for sitting on ground with props spinning.
1243us (fast idle). For landing pattern – sometimes I change to slow idle (1193us) just before landing.
1980us (full power). Futaba rate is +100.
Advancing throttle curve has delay of 24 (about 4 seconds).
Reducing throttle curve has delay of 21 (about 3.5 seconds).

Normal throttle curve.
1652us (low power), rate is +29.
1980us (full power), rate is +100.
Advancing throttle curve has delay of 22.
Reducing throttle curve has delay of 20.
Because the throttle is moving over a much smaller range, the time it is taking to go from lowest to highest throttle in this curve is about 0.8 seconds, and about 1 second.

Spin throttle curve
1213us (medium idle). Futaba rate is -61.
1980us (full power). Futaba rate is +100.
Advancing throttle curve has delay of 24.
Reducing throttle curve has delay of 21.

Stall Turn throttle curve
1243us (fast idle). Futaba rate is -55.
1980us (full power). Futaba rate is +100.
Advancing throttle curve has delay of 21.
Reducing throttle curve has delay of 20.

With this setup, the throttle response is quite crisp at all times in the air - the D3 is extremely powerful. Under some flight conditions, it is possible to have a prop "buffeting" sound if the throttle is reduced too quickly. I believe this sound comes from the relative prop disc RPMs getting very slow. Once this happens, blipping the throttle will bring the RPM back up, and the buffeting sound goes away. The buffeting can also be avoided by using a higher RPM for low power (also reduces maximum braking), or increasing the delay time when reducing the throttle (makes the throttle feel sluggish to me). It definitely took quite a few flights to get the overall throttle feel I wanted in the air, and it is definitely different than flying a traditional ESC. Some pictures are attached to show the shape of the throttle curves.






Old 12-21-2019, 02:18 PM
  #1929  
Henning
 
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Thanks Dave

I installed the D3 ESC today in my old trusty Accuracy Mono from Naruke Hobby that will be my testbed over the winter. Looking at your Normal throttle curve I will have to do some adjustments to what I have set up. My curve look more like the one you are using for Stall Turn.

Interesting to se the servo speed you are using. I set the speed to 10 both in and out but will increase them to 20 and adjust from there.

Br

Henning
Old 12-21-2019, 03:29 PM
  #1930  
PeterP
 
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Henning,

Remember to use the physical throttle stick as your downline mix Master and not the throttle output.
Old 12-21-2019, 06:13 PM
  #1931  
DaveL322
 
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Henning,

It will be interesting to see what curves and settings you like once you have a chance to fly and adjust the D3. I found the curves needed to be quite different between normal flying and stall turn / spin / landing. It might be possible to use only 2 curves, but I have the throttle curves activated in flight conditions that I use TO / Landing, spins, and stall turns.
Old 01-01-2020, 01:26 PM
  #1932  
Henning
 
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Originally Posted by DaveL322 View Post
Henning,

It will be interesting to see what curves and settings you like once you have a chance to fly and adjust the D3. I found the curves needed to be quite different between normal flying and stall turn / spin / landing. It might be possible to use only 2 curves, but I have the throttle curves activated in flight conditions that I use TO / Landing, spins, and stall turns.
Hi Dave and Peter,

The weather over the x-mas holiday has been good enough to test the D3 ESC. We only have 4 hours of flyable daylight at this time of the year but over some days I have logged 29 flights.

In general I like the D3 once in the air. The start up and landing sequence with changing throttle curves by a 3 pt switch will take some more time to get used to. I hope to get some more flights in the upcoming weekend.

V4 600 14 Pole Mejzlik 22x20F and 22x22R used for windy conditions.



Futaba 18MZ

ATV

Full 108%

Low 124%



Normal flight

Full 1.910 ms

Low 1.592 ms

Speed In 16 Out 16

I have reduced the full power on both the ATV and the throttle curve.



Idle 1.054 ms

Speed In 0 Out 10



Takeoff/Landing 1.210 ms

Speed In 16 Out 16



Throttle hold/off 0.953 ms



Spin 1.367 ms

Stall Turn 1.637 ms

Speed In 16 Out 16


Br

Henning







Last edited by Henning; 01-01-2020 at 01:30 PM.

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