4 ms·

This is often talked about in the case of Air Force One (which is supposed to be able to keep flying in case of a nuclear war, so that the president can survive

This is often talked about in the case of Air Force One (which is supposed to be able to keep flying in case of a nuclear war, so that the president can survive and order the military). The limiting factor is probably engine oil, e.g. this article suggests 2-3 days. https://executiveflyers.com/how-long-can-air-force-one-stay-in-the-air/ https://executiveflyers.com/how-long-can-air-force-one-stay-...

infecto 3y ago
Thanks for sharing. I never realized engine cycle times were so short on planes!
- deleted 3y ago
  [deleted]
- mulmen 3y ago
  > It’s generally recommended that aircraft engine oil should be replaced every 50 hours, otherwise the oil would turn to sludge and get contaminated, which would damage the engine. This sounds like piston engine advice. I’d be surprised if jet airliners are going in for oil changes twice a week.
  - civilitty 3y ago
    Jet engines constantly pump oil under pressure between the stator and rotors to provide lubricant for the radial bearings while sealing and cleaning them. It’s a completely different kind of oil to the kind you’d find in a piston engine and operates at a much higher temperature.
    - mulmen 3y ago
      Agreed but what’s the service interval on that oil? Does it get changed regularly or just topped off? It’s a piston plane but my understanding of the DC-3 is that it runs out of fuel around the same time it runs out of oil.
  - miovoid 3y ago
    Hybrid-electric propulsion systems can enhance flight endurance by separating propulsion and power generation tasks, individually optimizing each for specific stress levels aligned with mission requirements.
    - mulmen 3y ago
      Does the marginal efficiency make up for the added weight? Aircraft engines already operate in a very narrow envelope so they can be optimized for cruise.
  - miovoid 3y ago
    Hyllion Karno is a good example for power generation unit required ultra-low maintenance.
deleted 3y ago
[deleted]
ianburrell 3y ago
The new VC-25B aren’t going to have aerial refueling capability as cost saving measure. They do have longer range.
- throw0101b 3y ago
  > The new VC-25B aren’t going to have aerial refueling capability as cost saving measure. Also: the old VC-25A did/does have it, but it was never used in ~30 years of flying.

infecto 3y ago

Thanks for sharing. I never realized engine cycle times were so short on planes!

deleted 3y ago
[deleted]
mulmen 3y ago
> It’s generally recommended that aircraft engine oil should be replaced every 50 hours, otherwise the oil would turn to sludge and get contaminated, which would damage the engine. This sounds like piston engine advice. I’d be surprised if jet airliners are going in for oil changes twice a week.
- civilitty 3y ago
  Jet engines constantly pump oil under pressure between the stator and rotors to provide lubricant for the radial bearings while sealing and cleaning them. It’s a completely different kind of oil to the kind you’d find in a piston engine and operates at a much higher temperature.
  - mulmen 3y ago
    Agreed but what’s the service interval on that oil? Does it get changed regularly or just topped off? It’s a piston plane but my understanding of the DC-3 is that it runs out of fuel around the same time it runs out of oil.
- miovoid 3y ago
  Hybrid-electric propulsion systems can enhance flight endurance by separating propulsion and power generation tasks, individually optimizing each for specific stress levels aligned with mission requirements.
  - mulmen 3y ago
    Does the marginal efficiency make up for the added weight? Aircraft engines already operate in a very narrow envelope so they can be optimized for cruise.
- miovoid 3y ago
  Hyllion Karno is a good example for power generation unit required ultra-low maintenance.

deleted 3y ago

[deleted]

ianburrell 3y ago

The new VC-25B aren’t going to have aerial refueling capability as cost saving measure. They do have longer range.

throw0101b 3y ago
> The new VC-25B aren’t going to have aerial refueling capability as cost saving measure. Also: the old VC-25A did/does have it, but it was never used in ~30 years of flying.