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Post by speedy70 » 16 Aug 2018, 22:27

I am enjoying this aircraft a lot but seem to be getting a large amount of starter motor fuses blown and even burnt out starter motor.I do not run the starter excessively and think maybe this could be reduced in sensitivity.
Another thing that seems to happen too frequently is the pitot tube getting blocked.
Vitus you are doing a superb job on this aircraft.
Cheers Chris

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Location: Görlitz, Germany

Re: failures

Post by Vitus » 17 Aug 2018, 11:46

Hi Chris,
Thank you for your feedback. I lowered the probability of the blockage of all three barometric ports (static, cockpit, pitot) to now 10% of what it was before. So, with the new update it should be far less likely for you to encounter this problem.

As for the starter, this is an entirely different matter and a more complex issue altogether.
The blown fuse of course is merely the symptom of an underlying problem - the fuse blows when the current that goes through the connected circuit is higher than what the fuse can handle. And on a side note: all fuses have a max. rating which depends on the circuit they are protecting. For instance the rating for the starter circuit (protecting both starter motor and booster coils) has a rating of 60 Ampere, while the fuse for the position lights is only rated 20 Amperes. (and a side-note to the side-note: For simplicity reasons I didn't program differently rated spare fuses, which is why all fuses are replaced from the same box)
However, the rated value is not necessarily what the fuse ACTUALLY can handle. Instead, when you replace a fuse it's max. current is randomized by a normal distribution function with a variance of about +/-10%. This is why you sometimes can end up blowing a fuse, but when you replace it and try again it might just work - provided that there's nothing wrong with the starter or booster coils. Also note that you can sometimes remedy the situation by switching off all other consumers of the electrical system.

With the introduction of the heat-exchange module I also allowed for the starter motor and coils to heat up. This happens in two ways: since both of those devices are mounted to the engine, they receive conduction heat from the crankcase and they exchange heat energy through convection with the surrounding air (i.e. engine back). Also, the winding of the motor coils and the booster coils heat up when current passes through them. That is why you shouldn't engage the starter for too long and always make sure to allow it to cool down if the starting attempt failed. And there currently is a pitfall in the system: the starter button doesn't automatically reset after a successful engine start! You need to click on the button again to disengage the starter and booster, otherwise there will still be current running through the windings, slowly heating up the coils until they melt the insulation of the wires and short-circuit.

There's more to it, but I think I leave it at that for now.

Here's the good news: the starter logic will receive a major update since I want to incorporate the historical eclipse inertia starter in a future update. That means that the electric motor will be scaled down, needing less current to run and being thus more robust to the above failures.
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