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Hondajet is 35% more fuel efficient...?

Discussion in 'HondaJet' started by Norseman, Oct 21, 2012.

  1. Norseman

    Norseman Member

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    Funny looking airplane..Takes a while to get used to it. :p

    Would like to see a direct comparison with the same size and speed of a similar aircraft. If indeed the fuel flow is 35% less than the competition, it is nothing less than revolutionary.
  2. JetForums

    JetForums Publisher/Admin

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    As inverted as it might seem, Honda's taken an upright approach to proper laminar flow, which includes an over-the-wing engine mount. They approached the design with efficiency in mind, not unlike most of their transportation pursuits. That means getting back to the basics, by reducing weight and drag.

    The aircraft's entire structure became a study in natural laminar flow (NLF) airfoils that reduce drag by keeping the airflow attached to the wing surface to a greater degree than conventional airfoils, but they are particularly sensitive to leading-edge contamination, such as bugs, ice or even rain. The slightest contamination can dramatically increase drag, which ultimately lowers speed and increases fuel burn. The most efficient NLF designs use a thin wing, which is great for aerodynamics, but limits fuel capacity. In my past life, this was a subject of study during our development of super-cavitation hydrofoils for the Dept. of the Navy.

    NLF isn't just limited to wings. Careful consideration must be given to the entire structure and any connecting appendage. For example, the enlarged nose section on the Hondajet not only grants better visibility for the flight crew, but the bulbous shape of the nose also contributes to natural laminar flow, not unlike a bulbous bow on a ship. According to Hondajet's chief designer Michimasa Fujino, the design reduces overall fuselage drag by some 10 percent,

    Other areas that can reduce drag include wing attachment joints and any parasitic resistance such as rivets, or the mounting points (and placement) of the engines. The over-the-wing engine mount (OTWEM), originally pioneered on the VFW-Fokker 614, presents inherent stability questions, but Honda found a sweet spot that appears to overcome many prior concerns. What I find most intriguing is how Honda's engineers arrived at an offset pylon mount for the engines. Could it be to offset torque or does it minimize shock wave interference?

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  3. Norseman

    Norseman Member

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    Yeah, seen it before...

    Wonder if the next Honda Jet, or the whole series of them will have the same configuration..?

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  4. KCook

    KCook New Member

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    That nacelle offset could be just to simplify the engine mount frame? What puzzles me is the distance of the nacelle off the wing. Does that have anything to do with the stability issue?

    [​IMG]

    Kelly
  5. JetForums

    JetForums Publisher/Admin

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    I talked with a Honda engineer at the NBAA show and as I speculated, the pylon is offset to compensate for torque. The offset configuration provides two attachment points on the side of the engine; both high & low, granting a more secure engine mount in contrast to attaching directly to the bottom of the engine nacelle.

    I believe the height of the engine is two-fold; it places the thrust line on the same plane with the fuselage, thereby reducing pitch tendencies with changes in power, but also to reduce laminar interference above the wing. The intake of the engine is creating a large vacuum which could be disruptive to the negative pressure above the wing if mounted too closely. By the way, the image you attached above was taken at Honda's display at the NBAA. It was a nearly half scale model that was so realistic, even the turbofan blades were spinning.
  6. JetForums

    JetForums Publisher/Admin

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    Getting back on thread subject, Honda is going to extremes to achieve increased fuel efficiency by reducing drag. For example, the upper and lower wing skins are machined from bar-stock aluminum to remove the rivet-head imperfections normally found on the surface of a sheeted wing. The result is a super-smooth skin that is so thin, it is nearly see-thru. It's so light it can be lifted with your fingertips. This pic was taken at the NBAA show. It is the inside of the upper skin. I can't imagine loading a block of aluminum this size into into a three or five-axis milling machine...

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  7. aviator4512

    aviator4512 New Member

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    To piggyback on Carl's post - the interior of this airplane is surprisingly spacious when compared with that of it's classmates. It's club seating closely resembles that of a CJ1, however, the space inside is much roomier for taller people. The iPod/Bluetooth adaptable sound system is cleverly designed in the floor panels and delivers a nice sound. Aft, there is a belted lav which has an actual door and not just a curtain for privacy purposes. I really liked the capability to control cabin air, entertainment, and lighting from an iPad. These aircraft start out around $4.5m if you're interested.
  8. KCook

    KCook New Member

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    Good Lord Carl, that wing skin is amazing!
  9. rclark

    rclark New Member

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    I think it's a neat little plane, can't wait to see more user reports coming out on how she performs over time.