Combustion!... :)
SS1 had a high wing without the scarfed nozzle which effectively is similar
though opposite to the SS2 designed lower wing. This leads me to believe
the heavy pressure vessels in the leading edge of the SS2 wing may be the
main unplanned CG shift culprit.
I do recall in conversations with Burt Rutan that SS1 did have other flight
stability issues that were controllable. They basically took the approach
to fly through the design issues given the limited number of potential
flights within the planned program.
One of them in particular was SS1 entering a non commanded barrel roll that
showed up on the first Xprize flight, flying a 90 degree vertical flight
profile. They flew the second one about 5 degrees off vertical which put
the wings in a lifting attitude which substantially reduced the
tendency for the spacecraft to roll.
Brian Feeney
President CEO - CTO
Alaia Design Group
alaiadesign@xxxxxxxxx
On Tue, Jan 5, 2021 at 6:16 PM Brian Feeney <alaiadesign@xxxxxxxxx> wrote:
I would agree that the CG has shifted, unless this was their intention to
scarf the nozzle from the beginning with the low wing design.
The only thing that comes to mind are the high pressure helium (other
gas?) pressure vessels that are placed in the leading edge of the wing.
I believe these were added after the fact to provide helium gas injection
into the hybrid engine to deal with some bombustion anomalies. If this is
the case it would have been an unplanned added weight.
Cheers Brian
-----------------
Brian Feeney
President CEO - CTO
Alaia Design Group
alaiadesign@xxxxxxxxx
On Tue, Jan 5, 2021 at 5:17 PM Michael Kelly <dmarc-noreply@xxxxxxxxxxxxx>
wrote:
Does anyone know why VG has scarfed the SpaceShip 2 nozzle fairly
dramatically? I've seen it in videos from two different flights, so
it isn't a one-off. The only explanation I can imagine is that the CG of
SS2 has shifted (it would be lower than originally designed). It's
puzzling that VG would accept the performance loss associated with
scarfing, rather than reworking the CNT to slightly angle the full nozzle.
Forgive me if this has been asked and answered; I somehow unsubscribed to
arocket for a time, and may have missed it.