A while back, I asked about whether Virgin Galactic's "plane" could be
upgraded to ballistically do suborbital and be useful to travel from A
to B. The answers were "not even close" (and that was understatement
since it reaches 100km altitude with speed of 0, and doing New York
Sydney ballistically requires near-orbital speed and thus heat shields).

So now I ask about flying A to B more conventionally with "wings".

Lets assume one had magical engines that suck in vacuum and pushed it to
the back to generate any thrust we wanted. (some pixie dust may be
involved :-).

Say we fitted those engines on a Concorde.

Concorde ezperienced tolerable skin heating of X° cruising at Mach 2 at
60,000 feet.

Could one raise altitude and maintain lift by increasing speed all the
way to near Kaman line?

Would lift generated by wings and heating of skin have linear
relationships since both depend on airspeed and density of air? or would
skin heating increase at faster rate than lift as you scale
altitude/airspeed?

aka: if the goal is just to maintain lift to keep weight of Concorde at
same altutude, can you raise aotutude and speed while keeping skin
heating to basically the same X°? (goal is not to go as fast as
possible, just keep flying but at higher speed/altitude).

From aerodynamics point of view, would the shape of Concorde scale to
higher speeds/higher altitude if the increased speed matches the need to
maiintain the same aerodynamic lift generation?

Would speed needed to generate lift from such wings scale to near
orbital speed well below Kaman line or near it?

I assume someone has simulated a Concorde and done what speed is needed
at what altitude to maintain lift? Curious on how high/fast the
airedynamci plane could fly if you remove the engine limitations from
equation.

From a descent point of view, is it correct to state that as long as the
plane "flies" (aka its weight carried by lift geerated by wings) it can
use the friction to slow it down (engines generate 0 thrust) so it can
progressively descend while always keeping a speed that doesn't exceed
heating limitations for skin?

JF Mezei is guilty of <lQ1aJ.185767$rl3.183257@fx45.iad> as of
10/14/2021 3:05:04 PM
> A while back, I asked about whether Virgin Galactic's "plane" could be
> upgraded to ballistically do suborbital and be useful to travel from A
> to B. The answers were "not even close" (and that was understatement
> since it reaches 100km altitude with speed of 0, and doing New York
> Sydney ballistically requires near-orbital speed and thus heat shields).
>
> So now I ask about flying A to B more conventionally with "wings".
>
> Lets assume one had magical engines that suck in vacuum and pushed it to
> the back to generate any thrust we wanted. (some pixie dust may be
> involved :-).
>
> Say we fitted those engines on a Concorde.
>
> Concorde ezperienced tolerable skin heating of X° cruising at Mach 2 at
> 60,000 feet.
>
> Could one raise altitude and maintain lift by increasing speed all the
> way to near Kaman line?
>
> Would lift generated by wings and heating of skin have linear
> relationships since both depend on airspeed and density of air? or would
> skin heating increase at faster rate than lift as you scale
> altitude/airspeed?
>
> aka: if the goal is just to maintain lift to keep weight of Concorde at
> same altutude, can you raise aotutude and speed while keeping skin
> heating to basically the same X°? (goal is not to go as fast as
> possible, just keep flying but at higher speed/altitude).
>
> From aerodynamics point of view, would the shape of Concorde scale to
> higher speeds/higher altitude if the increased speed matches the need to
> maiintain the same aerodynamic lift generation?
>
> Would speed needed to generate lift from such wings scale to near
> orbital speed well below Kaman line or near it?
>
> I assume someone has simulated a Concorde and done what speed is needed
> at what altitude to maintain lift? Curious on how high/fast the
> airedynamci plane could fly if you remove the engine limitations from
> equation.
>
> From a descent point of view, is it correct to state that as long as the
> plane "flies" (aka its weight carried by lift geerated by wings) it can
> use the friction to slow it down (engines generate 0 thrust) so it can
> progressively descend while always keeping a speed that doesn't exceed
> heating limitations for skin?

Hypersonic craft don't seem to look much like a Concorde.

<URL:https://en.wikipedia.org/wiki/NASA_X-43>
<URL:https://en.wikipedia.org/wiki/Boeing_X-51_Waverider>

/dps

--
I have always been glad we weren't killed that night. I do not know
any particular reason, but I have always been glad.
_Roughing It_, Mark Twain

On 2021-10-15 03:16, Snidely wrote:

> Hypersonic craft don't seem to look much like a Concorde.
>
> <URL:https://en.wikipedia.org/wiki/NASA_X-43>
> <URL:https://en.wikipedia.org/wiki/Boeing_X-51_Waverider>

But my question was more about taking more conventional delta wing and
seeing how high/fast it could go (assuming magical engines that work at
any altitude), and not for a 10 second joy ride to nowhere in a rocket ,
but for a multi hour flight that transports people over long distances.

Just this Friday, JF Mezei explained that ...
> On 2021-10-15 03:16, Snidely wrote:
>
>> Hypersonic craft don't seem to look much like a Concorde.
>>
>> <URL:https://en.wikipedia.org/wiki/NASA_X-43>
>> <URL:https://en.wikipedia.org/wiki/Boeing_X-51_Waverider>
>
>
>
> But my question was more about taking more conventional delta wing and
> seeing how high/fast it could go (assuming magical engines that work at
> any altitude), and not for a 10 second joy ride to nowhere in a rocket ,
> but for a multi hour flight that transports people over long distances.

Based on the difference in wing and body shape, I'm going to say "Mach
2, but maybe not even Mach 3". The Concorde has a /lot/ of surface
area. Much more than the Mach 2 F-104 Starfighter.

BTW, Jalopnik.com has an article about a CF-104D that's for sale, if
you want to do some experimenting.

/dps

--
Who, me? And what lacuna?

On 2021-10-15 16:35, Snidely wrote:

> Based on the difference in wing and body shape, I'm going to say "Mach
> 2, but maybe not even Mach 3". The Concorde has a /lot/ of surface
> area. Much more than the Mach 2 F-104 Starfighter.

Concorde carries 100 passengers. A military fighter carries one or maybe
2. So obviously, you need bigger wings to generate more lift as you
carrier bigger load.

Just this Friday, JF Mezei puzzled about:
> On 2021-10-15 16:35, Snidely wrote:
>
>> Based on the difference in wing and body shape, I'm going to say "Mach
>> 2, but maybe not even Mach 3". The Concorde has a /lot/ of surface
>> area. Much more than the Mach 2 F-104 Starfighter.
>
>
> Concorde carries 100 passengers. A military fighter carries one or maybe
> 2. So obviously, you need bigger wings to generate more lift as you
> carrier bigger load.

And bigger wings mean more drag, which means more heating. Does drag
got up as V-squared? Is the Concorde made out of vanadium?

/dps

--
There's nothing inherently wrong with Big Data. What matters, as it
does for Arnold Lund in California or Richard Rothman in Baltimore, are
the questions -- old and new, good and bad -- this newest tool lets us
ask. (R. Lerhman, CSMonitor.com)

On 2021-10-15 20:23, Snidely wrote:

> And bigger wings mean more drag, which means more heating. Does drag
> got up as V-squared? Is the Concorde made out of vanadium?

My question pertains exactly to this.

If plane supports the heat at Mach 2 at 60,000feet, would it sustain
the same heat if it climbed to say 80,000 and accelerated so that wings
would produce equal amount of lift as it did at Mach 2 at 60,000 ?

If the wings generate the same amount of lift, wouldn't that mean equal
amount of drag and thus heating?

Again, I am not asking about accelerating the Concorde to a gazillion
kmh or mach 10. Wondering if you exclude engine limitations, you could
make it climb much higher and go at higher speed to match the
lift/drag/heating it got at Mach 2 at 60,000.

On Oct/16/2021 at 04:12, JF Mezei wrote :
> On 2021-10-15 20:23, Snidely wrote:
>
>> And bigger wings mean more drag, which means more heating. Does drag
>> got up as V-squared? Is the Concorde made out of vanadium?
>
>
> My question pertains exactly to this.
>
> If plane supports the heat at Mach 2 at 60,000feet, would it sustain
> the same heat if it climbed to say 80,000 and accelerated so that wings
> would produce equal amount of lift as it did at Mach 2 at 60,000 ?
>
> If the wings generate the same amount of lift, wouldn't that mean equal
> amount of drag and thus heating?
>
> Again, I am not asking about accelerating the Concorde to a gazillion
> kmh or mach 10. Wondering if you exclude engine limitations, you could
> make it climb much higher and go at higher speed to match the
> lift/drag/heating it got at Mach 2 at 60,000.

If I recall correctly, heating goes up with speed to the power three.
The energy of a collision with a molecule of air goes up with the square
of the speed. But since you hit twice as much air when you go twice the
speed you get the power three, two for the energy per molecule hit and
one for the amount of molecules you hit. Again, if I recall correctly,
lift is only proportional to the square of the speed. In both cases,
heating and lift are proportional to air density. So as you go faster,
you can go higher (lower air density) and still have the same lift, but
you have more heating. Or you could go much higher and have the same
heating, but then you lose some lift, so you can't do that very much.

So the answer to your question is no, you can't keep the same heating
and lift by going higher.

In your example with mach 2 at 60,000 feet. If you go to 80,000 feet,
you have roughly half the air pressure you had at 60,000 feet, so you
would need to go at roughly mach 2*sqrt(2) to have the same lift. But
then your heat load would increase by sqrt(2). The heat load being
multiplied by sqrt(2) to the power three because of higher speed and
divided by 2 because of lower air pressure. This is only a rough
approximation, according to the shape of the plane you can have
different effect sizes, but as a first approximation this should give
you an idea of what is going on.

Alain Fournier

On Oct/16/2021 at 04:12, JF Mezei wrote :
> On 2021-10-15 20:23, Snidely wrote:
>
>> And bigger wings mean more drag, which means more heating. Does drag
>> got up as V-squared? Is the Concorde made out of vanadium?
>
>
> My question pertains exactly to this.
>
> If plane supports the heat at Mach 2 at 60,000feet, would it sustain
> the same heat if it climbed to say 80,000 and accelerated so that wings
> would produce equal amount of lift as it did at Mach 2 at 60,000 ?
>
> If the wings generate the same amount of lift, wouldn't that mean equal
> amount of drag and thus heating?
>
> Again, I am not asking about accelerating the Concorde to a gazillion
> kmh or mach 10. Wondering if you exclude engine limitations, you could
> make it climb much higher and go at higher speed to match the
> lift/drag/heating it got at Mach 2 at 60,000.

An interesting side note about this is that if you keep going faster and
higher in order have the same lift, you should reach approximately
orbital speed at 100 km. So at that point you are no longer flying but
orbiting. That is the reasoning behind the definition of the Karman
line. You can't fly above 100 km because to fly there, you need to reach
orbital speed and therefore you are orbiting not flying. And you can't
orbit below the Karman line because at orbital speed below the Karman
line you have enough lift to fly which means you will also have enough
drag that you won't orbit.

Alain Fournier

On 2021-10-16 11:29, Alain Fournier wrote:

> If I recall correctly, heating goes up with speed to the power three.

> one for the amount of molecules you hit. Again, if I recall correctly,
> lift is only proportional to the square of the speed.

Thanks.

However, how does that work as you approach Karman? Skin heating above
it is basically 0, right?

What sort of math/physics kick in to start reduction of heating as you
increase speed/altitude such that you get to 0 heating above Karman?

(Also I assume wings would eventually stop producing lift at speeds that
are too high for their design and air too thin for their design). But am
curious on what the limits would be in terms of altitude and speed for
"flight". (since suborbital really requires orbiutal class rocket and
that makes for New Yor to Sydney not being realistic).

On Oct/16/2021 at 17:31, JF Mezei wrote :
> On 2021-10-16 11:29, Alain Fournier wrote:
>
>> If I recall correctly, heating goes up with speed to the power three.
>
>> one for the amount of molecules you hit. Again, if I recall correctly,
>> lift is only proportional to the square of the speed.
>
> Thanks.
>
> However, how does that work as you approach Karman? Skin heating above
> it is basically 0, right?
>
> What sort of math/physics kick in to start reduction of heating as you
> increase speed/altitude such that you get to 0 heating above Karman?
>
> (Also I assume wings would eventually stop producing lift at speeds that
> are too high for their design and air too thin for their design). But am
> curious on what the limits would be in terms of altitude and speed for
> "flight". (since suborbital really requires orbiutal class rocket and
> that makes for New Yor to Sydney not being realistic).

At the Karman line, if you are moving at orbital speed which is also
approximately the speed you need to have enough aero-dynamic lift to
support your weight, then heating is very severe. But every six
kilo-meters higher you go, the density of the atmosphere decreases by a
factor of about two, and therefore if you stay at the same speed the
heating is divided by two. So at 160 kilo-meters, you have divided by
1000 your heating and you are now in an orbit that is sustainable for
for a short time. You never get zero heating, ISS is heated by
aerodynamic drag, but by factor of about a trillionth of the already
very low heating it would have at an altitude of 160 kilo-meters.

Same goes for your question about wings producing lift. Lift never goes
down to zero. You could theoretically get lift with wings at the
altitude of ISS. It is only that you would need to go at about thirty
million times orbital speed to have enough aero-dynamic lift to hold
your weight.

Alain Fournier

On Oct/16/2021 at 19:32, Alain Fournier wrote :

> Same goes for your question about wings producing lift. Lift never goes
> down to zero. You could theoretically get lift with wings at the
> altitude of ISS. It is only that you would need to go at about thirty
> million times orbital speed to have enough aero-dynamic lift to hold
> your weight.

Oups! Thirty million times orbital speed is more than the speed of light
so that wouldn't work. At very close to the speed of light you could get
some lift (lift would increase due to some relativistic effects). But of
course heating would vaporize your wings if you have get lift because of
relativistic effects near the speed of light.

Alain Fournier

Alain Fournier <alain245@videotron.ca> wrote:

> An interesting side note about this is that if you keep going faster
> and higher in order have the same lift, you should reach approximately
> orbital speed at 100 km. So at that point you are no longer flying but
> orbiting. That is the reasoning behind the definition of the Karman
> line. You can't fly above 100 km because to fly there, you need to
> reach orbital speed and therefore you are orbiting not flying. And you
> can't orbit below the Karman line because at orbital speed below the
> Karman line you have enough lift to fly which means you will also have
> enough drag that you won't orbit.

In the final chapter of his autobiography Kármán addresses the issue of
the edge of outer space:
Where space begins… can actually be determined by the speed of
the space vehicle and its altitude above the Earth. Consider,
for instance, the record flight of Captain Iven Carl Kincheloe
Jr. in an X-2 rocket plane. Kincheloe flew 2000 miles per hour
(3,200 km/h) at 126,000 feet (38,500 m), or 24 miles up. At this
altitude and speed, aerodynamic lift still carries 98 percent of
the weight of the plane, and only two percent is carried by
inertia, or Kepler Force, as space scientists call it. But at
300,000 feet (91,440 m) or 57 miles up, this relationship is
reversed because there is no longer any air to contribute lift:
only inertia prevails. This is certainly a physical boundary,
where aerodynamics stops and astronautics begins, and so I
thought why should it not also be a jurisdictional boundary?
Haley has kindly called it the Kármán Jurisdictional Line. Below
this line, space belongs to each country. Above this level there
would be free space.
-- https://en.wikipedia.org/wiki/Karman_line
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