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  • Shuttle flying

    From JF Mezei@21:1/5 to All on Fri Oct 8 21:12:27 2021
    Just watched Scott Manley's "Shuttle landing" video. https://youtu.be/pfNQW4jToHE

    I was always told the Shuttle had the flying properties of a brick.

    Yet, Enterprise had problems landing a couple of times since it still
    created lift and stayed up longer than expected on the sand sunway.
    The video susprised me because I truly expected it to firmly touch
    ground with no ability to hover.


    Apparently Enterprise's mass was made equivalent to the real shuttles.
    Did the real shuttles truly have such flying abilities once over runway&
    or did they ensure that it had bled off more speed before runway
    threshold to prevent this and ensure a prompt landing without enough
    energy to hover ?

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  • From Otto J. Makela@21:1/5 to JF Mezei on Sat Oct 9 16:30:34 2021
    JF Mezei <[email protected]> wrote:

    Just watched Scott Manley's "Shuttle landing" video. https://youtu.be/pfNQW4jToHE

    I was always told the Shuttle had the flying properties of a brick.

    Yet, Enterprise had problems landing a couple of times since it still
    created lift and stayed up longer than expected on the sand sunway.
    The video susprised me because I truly expected it to firmly touch
    ground with no ability to hover.

    I believe the strong ground effect created by the large flat bottom of
    the shuttle had a part in these initial difficulties?

    Ground effects, according to Ref. A-I are negligible when the
    Shuttle is at least one wing span above ground level, but do
    become significant when the ground vehicle is within � wing span
    of the ground.

    https://ntrs.nasa.gov/api/citations/19840006090/downloads/19840006090.pdf

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  • From JF Mezei@21:1/5 to Otto J. Makela on Sun Oct 10 02:38:12 2021
    On 2021-10-09 09:30, Otto J. Makela wrote:

    I believe the strong ground effect created by the large flat bottom of
    the shuttle had a part in these initial difficulties?

    That makes sense I guess. i was just very surprised to see that shuttle actually gain a few feet and stay up for an eternety (a few seconds).

    My "image" of the shuttle is that there was no way for it to do this and
    the main gear HAD to fall to the ground, abd the only control they had
    was keeping nose up to bleed speed before lowering it.

    Perhaps they changed the approach to ensure the shuttle had lower
    airspeed at the runway which would explain the "main gear must fall to
    the ground" while in early tests, a higher speed allowed that ground
    effect "flight".

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  • From Niklas Holsti@21:1/5 to JF Mezei on Sun Oct 10 12:29:43 2021
    On 2021-10-10 9:38, JF Mezei wrote:
    On 2021-10-09 09:30, Otto J. Makela wrote:

    I believe the strong ground effect created by the large flat bottom of
    the shuttle had a part in these initial difficulties?

    That makes sense I guess. i was just very surprised to see that shuttle actually gain a few feet and stay up for an eternety (a few seconds).

    My "image" of the shuttle is that there was no way for it to do this and
    the main gear HAD to fall to the ground, abd the only control they had
    was keeping nose up to bleed speed before lowering it.

    Perhaps they changed the approach to ensure the shuttle had lower
    airspeed at the runway which would explain the "main gear must fall to
    the ground" while in early tests, a higher speed allowed that ground
    effect "flight".


    In the video, Scott Manley clearly explains that the bouncy landing was
    due to pilot-induced oscillation (PIO) through the fly-by-wire system,
    and that it was fixed by correcting the fly-by-wire control algorithms.

    PIO is usually caused by too long delays in responses to manual control
    inputs. For the Shuttle there was (also?) another problem that the same
    control surfaces were used for both roll and pitch, instead of having
    separate controls, as Manley explains. It seems likely that the ground
    effect also played a role by increasing lift at low altitude.

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  • From JF Mezei@21:1/5 to Niklas Holsti on Sun Oct 10 21:33:25 2021
    On 2021-10-10 05:29, Niklas Holsti wrote:

    In the video, Scott Manley clearly explains that the bouncy landing was
    due to pilot-induced oscillation (PIO) through the fly-by-wire system,
    and that it was fixed by correcting the fly-by-wire control algorithms.


    Yes. but that means that the Shuttle still had enough energy and "lift"
    to not only be able to stop its descent but rise a few feet and stay up
    for some time. (as opposed to the saying that it had the flying
    capabilities of a brick (which can only go down).

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  • From Snidely@21:1/5 to All on Mon Oct 11 14:12:16 2021
    On Sunday, JF Mezei queried:
    On 2021-10-10 05:29, Niklas Holsti wrote:

    In the video, Scott Manley clearly explains that the bouncy landing was
    due to pilot-induced oscillation (PIO) through the fly-by-wire system,
    and that it was fixed by correcting the fly-by-wire control algorithms.


    Yes. but that means that the Shuttle still had enough energy and "lift"
    to not only be able to stop its descent but rise a few feet and stay up
    for some time. (as opposed to the saying that it had the flying
    capabilities of a brick (which can only go down).

    Bricks generate lift when they are moving fast enough. Paper gliders
    generate lift when they are moving fast enough. The difference is in
    v-min.


    /dps

    --
    Maybe C282Y is simply one of the hangers-on, a groupie following a
    future guitar god of the human genome: an allele with undiscovered
    virtuosity, currently soloing in obscurity in Mom's garage.
    Bradley Wertheim, theAtlantic.com, Jan 10 2013

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