1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Hypermiling through the air

Discussion in 'Gen 2 Prius Main Forum' started by ForTheGlory, May 5, 2008.

  1. ForTheGlory

    ForTheGlory New Member

    Joined:
    Feb 14, 2008
    296
    1
    0
    Location:
    Maryland
    Vehicle:
    2008 Prius
    The following article is from today's Daily Telegraph in London:

     
  2. ZC1

    ZC1 Junior Prius Owner

    Joined:
    Apr 18, 2008
    711
    13
    0
    Location:
    Metro Detroit
    Vehicle:
    2008 Prius
    Lawyers, get set, ready, go.
     
  3. Janus

    Janus Drug Pilot

    Joined:
    May 2, 2008
    10
    0
    0
    Location:
    Marlboro Country, MA
    Vehicle:
    2008 Prius
    That's nothing new for general aviation pilots. We've been figuring out ways to save money while flying ever since the Wright brothers. It has no impact on safety at all.
     
  4. patsparks

    patsparks An Aussie perspective

    Joined:
    Jul 12, 2007
    10,664
    567
    0
    Location:
    Adelaide South Australia
    Vehicle:
    2004 Prius
    Model:
    N/A
    They are extending the flight schedule to allow slightly lower cruise speed, I don't see the big deal. Dropping the speed from the 900km/h to say 850 to 875km/h would reduce drag while only extending the time of a 10 hour flight from Singapore to London would be extended by 20 to 30 minutes and could save a lot of fuel.

    They aren't talking about shutting the engines down and gliding from 11,000 metres down to 7,000 metres before restating the engines for the next pulse.

    Are they?

    The landing would still be the same, in fact I doubt a passenger will notice a change, the engines will be running and they will still reverse thrust to stop on the runway. I doubt the plan is to run on the grass or lower the tyre pressures for added rolling resistance
     
  5. ForTheGlory

    ForTheGlory New Member

    Joined:
    Feb 14, 2008
    296
    1
    0
    Location:
    Maryland
    Vehicle:
    2008 Prius
    Why?
     
  6. ZC1

    ZC1 Junior Prius Owner

    Joined:
    Apr 18, 2008
    711
    13
    0
    Location:
    Metro Detroit
    Vehicle:
    2008 Prius
    [Thinking of commercial jets]
    So pilots are backing off the throttle till coasting is achieved?

    Coasting in my understanding is flight without direct engine involvement, meaning no propulsional thrust is applied.
    Assuming straight and level flight, how long will a 176,000+ aircraft at 450-500knots stay at altitude by spooling down the engines to idle and how much fuel is consumed by spooling the engines back up to regain lost altitude?
    More than keeping the engines at speed?

    (I have no fixed wing experience, although I'm an FAA instrument rated commercial rotary wing pilot.)

    Taking the foot off the gas means traveling at reduced speed, which of course saves fuel and lengthens travel time. How is this new?

    Once again, define glide. Is gliding the same as coasting?

    I think the author of this article mixed up the terms Coasting, Gliding and Glide path (which is not mentioned) are different objects.
    Creating a complete continuous trajectory from cruising altitude to final landing is a good thing, and if computed accurately the jet engines can be reduced to idle during the trip down, saving fuel.
    But gliding (engines off)? Lawyers are smacking their lips.

    I think the following article from 2006, is a better explanation.
    NASA - NASA Helps Aircraft Glide Into A More Efficient Landing
     
  7. ForTheGlory

    ForTheGlory New Member

    Joined:
    Feb 14, 2008
    296
    1
    0
    Location:
    Maryland
    Vehicle:
    2008 Prius
    There's no way that they mean "gliding with engines off". Not only would that be stupid from a safety-of-flight perspective, but it would also waste tons of fuel. I'm sure that all they're planning to do is fly more slowly to save fuel. This article was somewhat poorly written in that it makes it sound like the airlines are doing something more complicated.

    As for "gliding in to landing", I'm sure that just means that they'll try to avoid making airplanes orbit the airport waiting for clearance to land.