S.P.A.R.K.S. Programming a kill switch for your electric

1. S.P.A.R.K.S.Programming a kill switch for your electric Alan Buckner Aug 3, 2011

2. Contents • What is a kill switch? • Why is a kill switch needed? • Live demo • Programming examples: • Spektrum example • Futaba example • Why do we need 100% offset?

3. What is a kill switch • Kill Switch Definition: A switch that will stop (kill) an engine or prevent a motor from operating. • Fuel Engines • Kill switch is needed to stop the engine from running after being started • Two types: • Throttle Cut feature, dependent on the throttle servo • Optoswitch. Required for some events. • What about Electrics? • Some ESCs are programmed to not start until the throttle is cycled. • I don’t know of any TX that has a kill switch feature for electrics

4. Why is a kill switch needed? Unlike a fuel plane, the issue is that electrics will start immediately when any of the following accidentally occur: • Your neck strap hits the throttle stick • You drop or tip over your transmitter • You hit it with your finger accidentally I have heard of many people being cut by props or damaging a plane due to this. I even know someone in this club who is very careful but needed stitches because of this. Accidents happen…

5. Live Demo

6. Spektrum Example 1 • It seems there are two ways to accomplish this which are similar. Example 1 is what I figured out through experimentation.

7. Spektrum Example 2 Example 2 is from: http://www.rc-soar.com/spektrum/index.htm Implementing a Throttle Kill function • There is no throttle kill function provided with the DX-7, instead there's 'Throttle Idle Recovery'. • For those who prefer a traditional Kill function, here's a solution which works off the MIX switch: • Use PMIX-5 or PMIX-6 • mix THRO->THRO • SW=MIX • Rate = -100 / -100 (note both negative) • Offset = -125 (note negative) Note 1: use only PMIX-5 or 6, otherwise the kill setting will vary with idle trim. Note 2: The kill position is adjusted via Offset.

8. Futaba Example – Page 1 • Throttle to throttle, linear mix • Note that trim is inhibited from affecting this mix

9. Futaba Example – Page 2 • Rates are opposite to negate the throttle • Rate B may not be necessary to set • For some reason, I needed 104% to fully stop the prop, even though trim should not affect this mix.

10. Futaba Example – Page 3 • Assigned to switch “G” • Note that mix “off” means “throttle stick active” so I changed the switch assignments.

11. Why do we need -100% offset? Bi-directional linear A Slave  B A  Master  B

12. Why do we need -100% offset? Bi-directional linear Bi-directional anti-linear A Slave  B A Slave  B A  Master  B A  Master  B

13. Why do we need -100% offset? Bi-directional linear Bi-directional anti-linear A Slave  B A Slave  B A Slave  0 A  Master  B A  Master  B 0 Master  A Uni-directional anti-linear

14. Why do we need -100% offset? Bi-directional linear Bi-directional anti-linear Slave Stick Slave Stick Slave Stick Slave Stick U  0 U  0  D U  0  D U 0  D 0 U D 0  U D 0  U D 0  U Master Stick Master Stick Master Stick Master Stick Uni-directional anti-linear Uni-directional anti-linear on dual axis Offset

15. Tips / Cautions • Depending on the transmitter and mix used, the throttle trim may still move the prop even with the kill switch activated. In many cases, this can be disabled. • Before turning on my TX, always ensure all switches are in their default positions, but there’s a catch on some transmitters. The mix “on” is actually throttle “off”. Spektrum TXs force “on” to be down/forward which is confusing. I loosened my switch and twisted it around  My Futaba allows me to program the switch direction. • After programming, hold the plane in case you programmed it incorrectly. It may go to full power! • Always ensure that your throttle stick is low before enabling or it may turn on at high throttle. • From what I have read, you cannot do this on the DX6i