So, Virgin Galactic did another flight.

The engine exhaust looked very strange to me, then I looked up on
Wikipedia, and apparently they burn plastic with nitroux ocyde as
oxydizer. Is that the case or did I misread of find reference to an
older ship?

From the point of view of the potential for this ship, apparently its
max speed is 4000kmh, or mach 3 (sea level)max altitude of 110km. Is
this straight up so its horizontal speed is 0 at apogee? Or does it
reach apogee with a horizontal speed closer to 4000kmh?

I undertsand it is nowhere hear to orbital speed. But am curious if this
could have transpotation potential?

In the end, for a suborbital London to Auckland NZ flight (halfway
around the globe), would the speed needed at MECO be closer to the
~25,000kmh needed for LEO and thus, the craft needs heat shields etc?

On 23-May-21 6:50 pm, JF Mezei wrote:
> So, Virgin Galactic did another flight.
>
> The engine exhaust looked very strange to me, then I looked up on
> Wikipedia, and apparently they burn plastic with nitroux ocyde as
> oxydizer. Is that the case or did I misread of find reference to an
> older ship?
>
> From the point of view of the potential for this ship, apparently its
> max speed is 4000kmh, or mach 3 (sea level)max altitude of 110km. Is
> this straight up so its horizontal speed is 0 at apogee? Or does it
> reach apogee with a horizontal speed closer to 4000kmh?
>
> I undertsand it is nowhere hear to orbital speed. But am curious if this
> could have transpotation potential?

No, there is no way this can evolve into anything other than a rich
man's toy. It's a dead end.

Sylvia.

On 2021-05-23 06:05, Sylvia Else wrote:

> No, there is no way this can evolve into anything other than a rich
> man's toy. It's a dead end.

Tried to use some ballistic trajectory calculator, but it assumes a flat
Earth :-( (aka: human throwing a ball in a park).

In orbit, I can understand the concept that as the satellite moves
forward, the curvature of Earth below results in the ground dropping
lower, and if you free fall down at the same rate as the ground drops,
then your altitude over ever changing ground remnains stable and you are
in orbit. is that correct understanding?

If I manage to travel 1/4 the way around the Earth, will the ground have
dropped by 6371m (Earth radius) ?

In the case of a suborbital London-Sydney flight, is this a case of
finding the right combo of altitude and speed at apogee/MECO such that
your fall rate is slow enough that you will travel most of the distance
before your altiutude drops to re-entry interface at which point you
become a glider and travel a few hundred km?

From a rocketry/mechanics point of view, is there an advantage of
climbing to higher altitude but lower speed vs staying lower but at
higher speed (assuming both get you to travel same distance before you
drop into re-entry atmosphere).

or do both result in the same burn and thus same delta V for the rocket
and is just a question of steering? (with lower altitude being faster
against slighthy thicker atmpsphere).

On 24-May-21 6:44 am, JF Mezei wrote:
> On 2021-05-23 06:05, Sylvia Else wrote:
>
>> No, there is no way this can evolve into anything other than a rich
>> man's toy. It's a dead end.
>
>
> Tried to use some ballistic trajectory calculator, but it assumes a flat
> Earth :-( (aka: human throwing a ball in a park).
>
> In orbit, I can understand the concept that as the satellite moves
> forward, the curvature of Earth below results in the ground dropping
> lower, and if you free fall down at the same rate as the ground drops,
> then your altitude over ever changing ground remnains stable and you are
> in orbit. is that correct understanding?
>
> If I manage to travel 1/4 the way around the Earth, will the ground have
> dropped by 6371m (Earth radius) ?
>
>
>
> In the case of a suborbital London-Sydney flight, is this a case of
> finding the right combo of altitude and speed at apogee/MECO such that
> your fall rate is slow enough that you will travel most of the distance
> before your altiutude drops to re-entry interface at which point you
> become a glider and travel a few hundred km?
>

The major problem is that you have to climb above essentially all the
atmosphere, or the the vehicle will melt from the heating caused by
moving through the atmosphere at such speeds. If you managed to avoid
the melting you'd still need continuing thrust (so need fuel, and lots
of it) to avoid slowing down. This is not practical.

So you have to achieve near orbital speed, or you'll come down short of
your target.

Now when re-entering, you have to get rid of all that kinetic energy,
without melting.

Virgin Galactic is completely ill-adapted to doing any of these things.

Sylvia.

In article <MHoqI.130783$9L1.109791@fx05.iad>,
jfmezei.spamnot@vaxination.ca says...
>
> So, Virgin Galactic did another flight.
>
> The engine exhaust looked very strange to me, then I looked up on
> Wikipedia, and apparently they burn plastic with nitroux ocyde as
> oxydizer. Is that the case or did I misread of find reference to an
> older ship?

They've always used this propellant combination. They had a fatal
nitrous oxide accident on the ground several years ago.

> From the point of view of the potential for this ship, apparently its
> max speed is 4000kmh, or mach 3 (sea level)max altitude of 110km. Is
> this straight up so its horizontal speed is 0 at apogee? Or does it
> reach apogee with a horizontal speed closer to 4000kmh?

I'm sure there is some horizontal component to its velocity, but only
Virgin Galactic knows the exact trajectory they fly.

> I undertsand it is nowhere hear to orbital speed. But am curious if this
> could have transpotation potential?

No. It doesn't fly high enough, or fast enough, to have transportation
potential. It's essentially a point design that allowed Spaceship One
to win the X-Prize. This "operational" version keeps much of the same
design features as the original Spaceship One. In fact, there is debate
over whether or not this thing actually reaches "space" and depends upon
the definition you use for the "boundary" of "space".

> In the end, for a suborbital London to Auckland NZ flight (halfway
> around the globe), would the speed needed at MECO be closer to the
> ~25,000kmh needed for LEO and thus, the craft needs heat shields etc?

That would be way outside the range of anything this barely suborbital
aircraft could achieve. Also, read up about how this thing does
reentry. It's essentially falling when it does so to minimize heating.
This destroys any possible range it would have when flying normally.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

Thanks for the reality checks.

Would it be correct to state that London-Sydney can either be achieved
with air breathing engines (aka: jet) flying with engines on all the
time and taking forever, or with a ballistic suborbital flight that
requires enough speed at MECO to be near orbital speed and thus heat
shields fro re-entry?

aka: Nothing in between?

I just googled altitude for re-entry interface and they state 100km. So
that Virgin Galactic at 110km i sbarely above it so clearly 110km isn't
enough to speed up to do ballistic trip halfway around the world.

So say you drop off a Dragon at near orbital speed over London with
intend to fall in Sydney harbour. From what altitude would drag be low
enough that its near obrital speed would be maintained long enough to
get it to Sydney?

Are we talking 200km? 300? 150?

Since Falcon9 drops its payload at 80km, this would mean a suborbital
flight to Sydney would require Dragon initiate its own burn, and then
ditch the service module to re-enter only as a capsule, right?

Somewhat ironic that the Shuttle may have been the best suited vehicle
for suborbital flights had its launch been simpler/safer.

On May/24/2021 at 12:21, JF Mezei wrote :
> Thanks for the reality checks.
>
> Would it be correct to state that London-Sydney can either be achieved
> with air breathing engines (aka: jet) flying with engines on all the
> time and taking forever, or with a ballistic suborbital flight that
> requires enough speed at MECO to be near orbital speed and thus heat
> shields fro re-entry?
>
> aka: Nothing in between?

You could theoretically have an aircraft with a small rocket engine that
would fire for an hour and do London to Sidney in an hour or two at
something like 40 km high. I don't think you could do it in a way that
would make economic sense, but I wouldn't entirely rule it out.

> I just googled altitude for re-entry interface and they state 100km. So
> that Virgin Galactic at 110km i sbarely above it so clearly 110km isn't
> enough to speed up to do ballistic trip halfway around the world.
>
> So say you drop off a Dragon at near orbital speed over London with
> intend to fall in Sydney harbour. From what altitude would drag be low
> enough that its near obrital speed would be maintained long enough to
> get it to Sydney?
>
> Are we talking 200km? 300? 150?

If I recall correctly, when a spacecraft de-orbits, it starts its
atmospheric deceleration about half an orbit from the landing point. So
at near orbital speed and at 100 km altitude, you would go about half
way around the globe.

> Since Falcon9 drops its payload at 80km, this would mean a suborbital
> flight to Sydney would require Dragon initiate its own burn, and then
> ditch the service module to re-enter only as a capsule, right?
>
>
> Somewhat ironic that the Shuttle may have been the best suited vehicle
> for suborbital flights had its launch been simpler/safer.

If its launch had been simpler/safer it wouldn't have been the Shuttle.

Alain Fournier