Tq U
On Wed, Mar 30, 2022 at 2:21 AM Norman Yarvin <yarvin@xxxxxxxxxxxx> wrote:
On Tue, Mar 29, 2022 at 04:09:56PM -0400, Henry Spencer wrote:
A proper aerospike eliminates much (not all) of the heating problem bynot
having a long solid spike; that also makes it lighter.
One thing I hadn't realized at first about where the heating
difficulty with a full spike comes from: the airflow around that spike
is *converging*. That means it's compressing and heating up. So this
is not just the normal difficulty of cooling a nozzle, and not just
the added difficulty of doing so at the end of a long thin spike where
it's hard to arrange cooling channels: it's even more than that.
A difficulty they had with the R101 airship was that the pressure at
the end of the tail was unexpectedly high and blew in the fabric
covering there. I think that was from the same root cause: converging
air resulting in higher pressure. They solved the problem quite
inelegantly by chopping off the tail; reinforcing it would have been
far better for drag.
