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 ?

JF Mezei <jfmezei.spamnot@vaxination.ca> 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 ½ wing span
of the ground.

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

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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".

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.

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).

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