I had a boss who was a pilot, and he told me this riddle:
Q: How do you measure altitude with a barometer?
A: Drop it and see how long it takes to hit the ground.
For example, I have an old Suunto Ambit watch that I used for outdoor activities and/or exercise. I found that because I was not wearing it all the time, it was not charged most of the time that I needed it.
Unfortunately no, and often it’s not trivial to legally install one.
But yeah, go experimental and then you never have to worry about these things. Lots of great value kit planes out there.
We're not talking about jetliners here. We could easily be talking about planes that are suitable for clear conditions only.
And yes, small planes used to have cigarette lighters.
There's an airworthiness directive from 1979 that required owners of a bunch of Cessna models to either disable the cigarette lighter or add a circuit protection device. There's a copy of that AD here [1]. It includes a big list of Cessna models and serial number ranges, which can give a good idea of how common cigarette lighters were.
[1] http://www.cessna172club.com/forum/ubbthreads.php?ubb=showfl...
You could trivially get a smaller than the iPad power bank with you and get up to days worth of battery life...
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