On 26/02/2018 3:32 AM, Alain Fournier wrote:
On Feb/25/2018 at 9:51 AM, Jeff Findley wrote :
In article ,
says...

"SpinLaunch is raising $30 million to use large centrifuges to power
catapult to
launch payloads into space. They use large centrifuges to store
energy and will
then rapidly transfer that momentum into a catapult to send a payload
to space at
up to 4,800 kilometers per hour (3,000 mph). If successful, the
acceleration
architecture is projected to be both lower cost and use much less
power, with the
price of a single space launch reduced to under US$500,000."

See:

https://www.nextbigfuture.com/2018/0...er-launch.html



Feasible?

Maybe. But quite challenging. At the high acceleration required by
this approach, the projectile must be fairly hardened. Also, at the
high low altitude speeds this thing will be traveling, atmospheric
heating is an issue. And finally, even if the catapult can get it to
orbital altitude and velocity, it will never get into orbit without a
rocket engine to circularize the orbit.

From the projectile's point of view, this isn't much different than the
past "gun launch" proposals. Pretty much all of the same issues apply.

Jeff


The issues of gun launch apply to SpinLaunch. But SpinLaunch has some
issues of its own. Having a payload at very high speed spinning in
the launch apparatus without tearing apart the whole thing would be
quite a challenge.

I might be wrong but I suspect those proposing SpinLaunch are aware of
the problems. Their business plan is probably more about collecting
investors money than about putting anything in orbit.

The issues are mentioned in the three page paper linked from the
article. They comment, amongst other things, that missiles have
electronics that has to stand 20,000g. No doubt that's true, but having
to design complete spacecraft to such a specification would be
demanding, and would surely hugely increase their mass. I don't see this
as being practical.

Sylvia.