Next Dragon Launch Due in October

In article m,
says...

How complex/difficult is it to target a capsule's landing precisely
(considering wind etc).

It's not terribly difficult. Capsules typically fly a "lifting"
trajectory due to the capsule's shape and offset center of gravity. The
lift to drag ratio isn't as good as a winged vehicle, but it's
sufficient to provide for a targeted landing. Reportedly, Dragon was
within a mile of the targeted landing spot.

The "fail safe" in a Soyuz capsule is to spin the capsule so that, over
time, the lift vector's direction is effectively nulled out. The
downside to this is that the trajectory cannot be controlled, which
usually means the Soyuz does not land anywhere near the intended
location.

Are parachutes in a capsule static, or are there mechanisms to move the
cords to change aerodynamics to aim the capsule (such as the type of
control skydivers have) ?

Historically, no. But there is no fundamental reason that a capsule
could not use a parafoil to control its final landing (ala X-38).
Alternatively, parachutes (simpler than parafoils) could be used to get
the capsule "close enough" to the landing site and then landing rockets
could be used for final powered descent and landing (ala Dragon).

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

"Jeff Findley" wrote in message
...

In article m,
says...

How complex/difficult is it to target a capsule's landing precisely
(considering wind etc).

It's not terribly difficult. Capsules typically fly a "lifting"
trajectory due to the capsule's shape and offset center of gravity. The
lift to drag ratio isn't as good as a winged vehicle, but it's
sufficient to provide for a targeted landing. Reportedly, Dragon was
within a mile of the targeted landing spot.

The "fail safe" in a Soyuz capsule is to spin the capsule so that, over
time, the lift vector's direction is effectively nulled out. The
downside to this is that the trajectory cannot be controlled, which
usually means the Soyuz does not land anywhere near the intended
location.

Are parachutes in a capsule static, or are there mechanisms to move the
cords to change aerodynamics to aim the capsule (such as the type of
control skydivers have) ?

Historically, no. But there is no fundamental reason that a capsule
could not use a parafoil to control its final landing (ala X-38).
Alternatively, parachutes (simpler than parafoils) could be used to get
the capsule "close enough" to the landing site and then landing rockets
could be used for final powered descent and landing (ala Dragon).

And there was some basic work done at trying to land Gemini via a parafoil
and land on a runway.

Jeff

--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net

theres enough open land and ocean precision targeting doesnt really
matter........

a lifting body coming down in the ocean is probably a bad day for
everyone.......

it certinally was for the shuttle.

capsules arent sexy but can land anywhere......

lifting bodies need runways that may not be available in a disaster

"bob haller" wrote in message
...



theres enough open land and ocean precision targeting doesnt really
matter........

a lifting body coming down in the ocean is probably a bad day for
everyone.......

it certinally was for the shuttle.

capsules arent sexy but can land anywhere......


Ayup. But that doesn't do you much good if the recovery craft are still 1000
miles away.


lifting bodies need runways that may not be available in a disaster


No, but lifting bodies already have a certain amount of crossrange
capability. So far that hasn't been an issue.

each method has its tradeoffs and benefits. I'm not convinced either one is
better than the other.




--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net