Troy:
Where do you get carbon / phenolic?
Bill
On Tuesday, December 1, 2015, Troy Prideaux <GEORDI@xxxxxxxxxxxxxxxx> wrote:
I’d be surprised if a typical expansion cone (especially most of a high
expansion cone) was constructed of carbon-carbon. Throat – yup, sure, but
as I’ve said previously - a very substantial fraction of a high expansion
cone will see relatively low temperatures and extremely low pressures. No I
haven’t constructed a vacuum optimised solid expansion cone, but if I did,
I’d do it exactly the same way I’ve been making my nozzles for the last 20
years – graphite throat with carbon-fibre/phenolic composite expansion
section and yes I could do it for a reasonable flight weight without too
much fuss. Sure, if the burn time was reasonably long or motor was of
substantial enough impulse, then I might have to implement a carbon-carbon
throat and take extra measure to handle the thermal energy.
To illustrate just how cold the exhaust flow can get for vacuum
optimised expansion – a typical LH2:LOX engine that’s being expanded to
something close to vacuum conditions will form **icicles** on the aft
edges of the expansion cone.
Troy
*From:* arocket-bounce@xxxxxxxxxxxxx
<javascript:_e(%7B%7D,'cvml','arocket-bounce@xxxxxxxxxxxxx');> [mailto:
arocket-bounce@xxxxxxxxxxxxx
<javascript:_e(%7B%7D,'cvml','arocket-bounce@xxxxxxxxxxxxx');>] *On
Behalf Of *Paul Breed
*Sent:* Wednesday, 2 December 2015 12:31 PM
*To:* arocket@xxxxxxxxxxxxx
<javascript:_e(%7B%7D,'cvml','arocket@xxxxxxxxxxxxx');>
*Subject:* [AR] Question for the solids guys...
If one was going to build a solid vacuum stage,
has anyone on this list built a flight weight high expansion ratio solid
motor?
Clearly just turning a steel or graphite solid expansion cone is either
low expansion ratio or not flight weight.
If its a simple long tubular solid the expansion cone is going to have to
be bigger than the case diameter....
Looking at professional vacuum stage solids one sees carbon carbon
expansion bells and fuel geometries that aren't the simple tubular solids
that typify the amateur solid...
Like:
http://104.131.251.97/spacerockets/wp-content/uploads/sites/17/2015/08/9166357_orig.jpg
)
