Landing gear on the shuttle

I was watching the live pics of STS-118 landing today and noticed that
the landing gear doesn't come down until what appears to be just
seconds (10-15?) before landing.

So what's the procedure if the gear doesn't come down? I'm pretty
sure a go-around isn't an option.

"nmp" wrote in message ...
djarvinen wrote:

I was watching the live pics of STS-118 landing today and noticed that
the landing gear doesn't come down until what appears to be just seconds
(10-15?) before landing.

So what's the procedure if the gear doesn't come down? I'm pretty sure
a go-around isn't an option.

I'm no technologist or expert but even I can figure that one out. The
procedure is: put her down with her belly on the ground, and let's see
what happens. Like you said, there is no alternative either way.

Could be a problem as the orbiter has a flat underside. Sounds like a recipe for a flip-over tail-over-nose.

On Aug 21, 9:59 am, djarvinen wrote:
I was watching the live pics of STS-118 landing today and noticed that
the landing gear doesn't come down until what appears to be just
seconds (10-15?) before landing.

So what's the procedure if the gear doesn't come down? I'm pretty
sure a go-around isn't an option.

It's gonna be a Bad Day if the gear doesn't come down. That's
why the design is such that they're extremely confident it
WILL come down.

I'm not sure if there's an official procedure, but I'm sure the
pilot would do the best they could to fly it like any other belly
landing. It's just that the orbiter is likely to fare much worse
on a gear-up landing than any ordinary airplane would fare.

On Aug 21, 10:07 am, "hg" wrote:
"nmp" wrote in ...
djarvinen wrote:

I was watching the live pics of STS-118 landing today and noticed that
the landing gear doesn't come down until what appears to be just seconds
(10-15?) before landing.

So what's the procedure if the gear doesn't come down? I'm pretty sure
a go-around isn't an option.

I'm no technologist or expert but even I can figure that one out. The
procedure is: put her down with her belly on the ground, and let's see
what happens. Like you said, there is no alternative either way.

Could be a problem as the orbiter has a flat underside. Sounds like a recipe for a flip-over tail-over-nose.

I was kind of wondering if they had some sort of emergency gear down
procedure; perhaps an explosive type mechanism that would force them
down. But it seems like the time frame is so small, that that kind of
solution might be worse than than no gear down at all.

Certainly they must have some plan, even if it is only 'hang on!'.

"djarvinen" escribió en el mensaje
oups.com...
On Aug 21, 10:07 am, "hg" wrote:
"nmp" wrote in
...
djarvinen wrote:

I was watching the live pics of STS-118 landing today and noticed that
the landing gear doesn't come down until what appears to be just
seconds
(10-15?) before landing.

So what's the procedure if the gear doesn't come down? I'm pretty
sure
a go-around isn't an option.

I'm no technologist or expert but even I can figure that one out. The
procedure is: put her down with her belly on the ground, and let's see
what happens. Like you said, there is no alternative either way.

Could be a problem as the orbiter has a flat underside. Sounds like a
recipe for a flip-over tail-over-nose.

I was kind of wondering if they had some sort of emergency gear down
procedure; perhaps an explosive type mechanism that would force them
down. But it seems like the time frame is so small, that that kind of
solution might be worse than than no gear down at all.

Certainly they must have some plan, even if it is only 'hang on!'.


http://www.globalsecurity.org/space/.../sts-gear.html
For deployment of the landing gear, the uplock hook for each gear is
activated by the flight crew initiating a gear-down command. The uplock hook
is hydraulically unlocked by hydraulic system 1 pressure applied to release
it from the roller on the strut to allow the gear, assisted by springs and
hydraulic actuators, to rotate down and aft. Mechanical linkage released by
each gear actuates the respective doors to the open position. The landing
gear reach the full-down and extended position within 10 seconds and are
locked in the down position by spring-loaded downlock bungees. If hydraulic
system 1 pressure is not available to release the uplock hook, a pyrotechnic
initiator at each landing gear uplock hook automatically releases the uplock
hook on each gear one second after the flight crew has commanded gear down.

--

Cheers

On Aug 21, 12:33 pm, "Javi" wrote:
"djarvinen" escribió en el mensajenews:1187723071..035284.281630@i13g2000prf. googlegroups.com...





On Aug 21, 10:07 am, "hg" wrote:
"nmp" wrote in
...
djarvinen wrote:

I was watching the live pics of STS-118 landing today and noticed that
the landing gear doesn't come down until what appears to be just
seconds
(10-15?) before landing.

So what's the procedure if the gear doesn't come down? I'm pretty
sure
a go-around isn't an option.

I'm no technologist or expert but even I can figure that one out. The
procedure is: put her down with her belly on the ground, and let's see
what happens. Like you said, there is no alternative either way.

Could be a problem as the orbiter has a flat underside. Sounds like a
recipe for a flip-over tail-over-nose.

I was kind of wondering if they had some sort of emergency gear down
procedure; perhaps an explosive type mechanism that would force them
down. But it seems like the time frame is so small, that that kind of
solution might be worse than than no gear down at all.

Certainly they must have some plan, even if it is only 'hang on!'.

http://www.globalsecurity.org/space/.../sts-gear.html
For deployment of the landing gear, the uplock hook for each gear is
activated by the flight crew initiating a gear-down command. The uplock hook
is hydraulically unlocked by hydraulic system 1 pressure applied to release
it from the roller on the strut to allow the gear, assisted by springs and
hydraulic actuators, to rotate down and aft. Mechanical linkage released by
each gear actuates the respective doors to the open position. The landing
gear reach the full-down and extended position within 10 seconds and are
locked in the down position by spring-loaded downlock bungees. If hydraulic
system 1 pressure is not available to release the uplock hook, a pyrotechnic
initiator at each landing gear uplock hook automatically releases the uplock
hook on each gear one second after the flight crew has commanded gear down.

Nice link, great info, thanks.

wrote in message
ups.com...
On Aug 21, 9:59 am, djarvinen wrote:
I was watching the live pics of STS-118 landing today and noticed that
the landing gear doesn't come down until what appears to be just
seconds (10-15?) before landing.

So what's the procedure if the gear doesn't come down? I'm pretty
sure a go-around isn't an option.

It's gonna be a Bad Day if the gear doesn't come down. That's
why the design is such that they're extremely confident it
WILL come down.

I'm not sure if there's an official procedure, but I'm sure the
pilot would do the best they could to fly it like any other belly
landing. It's just that the orbiter is likely to fare much worse
on a gear-up landing than any ordinary airplane would fare.

ISTR the problem with the belly landing is the angle of attack the shuttle
needs to kill the sink rate. Either the shuttle lands flat at very high
speed and sinkrate, or the "slapdown" of the nose is going to be pretty
extreme - not sure if its survivable for the crew or not, hope they never
have to find out!

On Aug 22, 4:03 am, "MichaelJP" wrote:
wrote in message

ups.com...



On Aug 21, 9:59 am, djarvinen wrote:
I was watching the live pics of STS-118 landing today and noticed that
the landing gear doesn't come down until what appears to be just
seconds (10-15?) before landing.

So what's the procedure if the gear doesn't come down? I'm pretty
sure a go-around isn't an option.

It's gonna be a Bad Day if the gear doesn't come down. That's
why the design is such that they're extremely confident it
WILL come down.

I'm not sure if there's an official procedure, but I'm sure the
pilot would do the best they could to fly it like any other belly
landing. It's just that the orbiter is likely to fare much worse
on a gear-up landing than any ordinary airplane would fare.

ISTR the problem with the belly landing is the angle of attack the shuttle
needs to kill the sink rate. Either the shuttle lands flat at very high
speed and sinkrate, or the "slapdown" of the nose is going to be pretty
extreme - not sure if its survivable for the crew or not, hope they never
have to find out!

I think i would prefer RTLS to that . . . and I truly hope they never
have to find out

take care . . .

John

"djarvinen" wrote in message
oups.com...
I was watching the live pics of STS-118 landing today and noticed that
the landing gear doesn't come down until what appears to be just
seconds (10-15?) before landing.

So what's the procedure if the gear doesn't come down? I'm pretty
sure a go-around isn't an option.

The gear is gravity deployed, but there is a back-up. If the gear does not
deploy and lock within a certain amount of time, pyrotechnic actuators are
fired which force the gear into the down and locked position.

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)

Originally Posted by djarvinen

I was watching the live pics of STS-118 landing today and noticed that
the landing gear doesn't come down until what appears to be just
seconds (10-15?) before landing.

So what's the procedure if the gear doesn't come down? I'm pretty
sure a go-around isn't an option.

The shuttle landing gear are deployed 'mechanically.' As such they require a bit of a 'pop' to deploy just before contact with the runway. This is an intentional design safety feature. My father was the lead engineer on the shuttle autoland system. Much argument was made when he insisted the gear be deployed without hydrolics etc. As a former air force pilot he knew a major cause of landing crashes resulted from the failure of gear failure to deploy. The orbiter landing gear are manually deployed by the flight crew (Pilot or Commander). The orbiter approaches the runway at the steepest angle and highest speed of any known glider. You are correct that that there are no re-do's. Any failure of the landing gear to deploy properly will lead to a catastrophic failure. At about 220mph there is no room for ripping down the runway hoping the 'belly' of the aircraft will hold up.
On a related note the recent Endeavor mission had a quandary. IF the damage was severe enough to place the crew at great risk was it possible to land the orbiter without a crew? The answer is yes. The only barrier to autolanding the orbiter is deploying the gear and a mechanism to do so could have been devised if it had been needed. Thankfully it was not. The alternative risk of launching a 'rescue shuttle' was great; this time all turned out well.
We are still flying an experimental 'spaceplane.' One which has no viable escape system--the only craft ever built to take people into space without a crew escape system. The next generation vehicle should focus on crew safety, not payload capacity and as such can have a full crew escape system integrated from the outset. Shuttle's have always been envisioned as a way to ferry people to and from orbit safely, not cargo. Cargo can be handled by 'dumb' boosters. Max Faget, whom I had the honor of interviewing many times never did get to see the shuttle he designed go into operation.

Keith E. McInnis