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Line tension controlled ESC timer

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Erik Janssen:
I have built a device that controls the ESC output as a function of line tension. I modified my 1994 Shanghai WCh model to accommodate this sensor timer and electric power plant. The model was originally built for a Super Tigre .46 and flown on the Dutch Nationals in 2009 to the 4th place within 100 points per flight of the winner. This is quite good as the model is now 16 years old, 6 oz heavier than with the .46 and the pilot had not flown a competition since 1996. I used a Castle Creations Speed Controller

This will allow you to fly in extreme conditions, I have test flown the setup to prove the potential in heavy winds and posted a movie on youtube

This is what it does:
The timer consists of a processor board and sensor that are put into the airplane. (18 gram) The LCD controller is used to set some flight parameters and stays on the ground.

When do I want it to work:
In level flight I want NO reaction from the controller, constant airspeed makes the model groove, constant groundspeed makes the model hunt.
In the low maneuvers I want NO reaction from the controller, ANY sign of 4-2-4 stroke makes the loops wider than high, so the sensitivity of the device is set in such a way that it barely hits the 4-2-4 stroke on the top of the loops.
In the double maneuvers and the verticals I DO want the sensor to open up the throttle.

How do I control it:
The ESC value (FLIV) is increased by a proportional factor (PPOS) multiplied with the loss of line tension (SENSOR VALUE) when the line tension is below the minimum line tension (GMIN)
IF SENSOR < GMIN THEN ESC OUT = FLIV + (PPOS * (GMIN – SENSOR VALUE))
IF ESC OUT > MAXV then ESC OUT = MAXV (to limit the maximum output)

The following parameters can be set to adjust the sensitivity:
FLIV   ESC OUT for Flight Value
WTHT   Walk to Handle Time, motor off
FLIT   Flight Time
PPOS   Proportional factor, defines the steepness of throttle up
MAXV   The maximum output, in moderate wind you may not need full throttle
GMIN   The line tension where you want the sensor to increase the output

Most surprising is that a horizontal and vertical eight normally take 10 secs with an IC model, in wind the overhead eight is then flown in 12 secs. My device opens the throttle in the overhead eights and I can fly them in 10 secs too.

Tech details:
The system is promising but needs more time to be developed further. The reaction of the system is fast, the processor running at 20mhz can do 10.000 sensor comparisons per second, I reduced this to 20 per second. The CC45 reacts very fast I am totally happy with the setup.
So from the PID controller I am only using the Proportional factor. I tried to add a Differentiator but this does not improve anything in the air. I do not intend to add an Integrator as I want the model to lose some speed anyhow.

Now all I need is a better airplane and more practice, seems that in 16 years nothing has changed.

Igor Burger:
Hi Eric, that number 26m/s is surprising, how did you measured it? By eye I think the wind was may be 8m/s. The landing looked like that, also I did not see any traversing in 8 overhead and hourglass which will be necessary in such wind. Was it a permanent wind 26m/s or just single gust?

Normaly people cannot stay on ground in such wind, I cannot imagine flying. :-)

Erik Janssen:
Thanks for the compliment, my flights always look as if there is not much wind, that seems to be the story of my life. I wanted to prove that the system could work in heavy wind conditions. My flying field is 5km away from an official website where the airport reports the weather. When returing home I make a copy of the weather conditions, see attachment. I grew up in Holland close to the sea where there is a lot of wind.

Normally in governor heavy wind blows you out of the sky and you cannot fly an hourglass. I proved that in Almere in Spring where the competition was cancelled and I flew my plane without a sensor and nearly lost it.

See how?

With the sensor the motor goes full throttle to battle the wind. I have logged in flight an ESC input of 57A on a 4S battery at the top of the hourglass.

At 45 degrees the line tension is reduced bij 0,7 and overhead the model hangs towards the pilot so the loss is 1g
I set my parameters in such a way that from 0,8g it starts adding throttle and at a loss of 1,2 it is on full throttle.

I compared the time needed per maneuvre of two very windy flights with the time Beriger needed in Spain in 2006. This shows that the sensor really helps to fly in wind, without the sensor I could not fly my hourglass.

Alan Hahn:
This needs a cross posting in the Electric Forum! (maybe I should look first and see if it already is.)

PerttiMe:
Doesn't the weather report say "windsnelheid (kts) 19" (19 knots)
??

Gusts 27 knots?

That is just under 10 m/s and 14 m/s. A good wind.
Or am I missing something?

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