So you confirmed it's not a contrail but a smoke trail from an APU
That video - definitely some problems with APU and nothing else.
Can they run these at the same time as regular plane engine while in flight or is this only used on the ground?
Usually only on the ground. After main engines starts, they become power source for plane systems and APU is turned off. However it could be run in flight in emergency as an spare power source if something happens with main engines.
The 'chemtrails' we refer to are actually purposeful releases of particulates from a substance in TANKS inside the jets
Above video is definitely not the case.
Chemtrails sprayers are usually placed on the rear edge of the wing or on the separate beam mount under the plane.
It will be insane to use gas-turbine engine for spraying something. Despite of theoretical ability to work on anything flammable, gas-turbine engines usually are finely adjusted to kerosene, and trying to burn or add something different to the fuel will damage them easily. It is much cheaper to use conventional pipe manifold with jets under the hull, than to constanly kill and replace expensive APUs.
That video - definitely some problems with APU and nothing else.
Usually only on the ground. After main engines starts, they become power source for plane systems and APU is turned off. However it could be run in flight in emergency as an spare power source if something happens with main engines.
Above video is definitely not the case.
Chemtrails sprayers are usually placed on the rear edge of the wing or on the separate beam mount under the plane.
It will be insane to use gas-turbine engine for spraying something. Despite of theoretical ability to work on anything flammable, gas-turbine engines usually are finely adjusted to kerosene, and trying to burn or add something different to the fuel will damage them easily. It is much cheaper to use conventional pipe manifold with jets under the hull, than to constanly kill and replace expensive APUs.