I should like to know the theoric energy in kwh necessary for keeping in air a kg for an hour ...
It is the problem of all the birds , drones, plains , helicopters.....
It is the number for calculating the efficienty of the fligth

On 8/9/2023 7:17 PM, nero wrote:
> I should like to know the theoric energy in kwh necessary for keeping in air a kg for an hour ...
> It is the problem of all the birds , drones, plains , helicopters.....
> It is the number for calculating the efficienty of the fligth

Generally speaking it is advised an individual achieve communication
skills before progressing to more advanced topics. As stated above
it is clear that you don't know enough to properly state the problem
you're attempting to solve. Stick with the accepted learning sequence
rather than jumping ahead into realms you're not yet capable of
understanding. Don't take this as a putdown, take it as a strong
suggestion that you slow down. The question(s) you're attempting
to ask will probably be resolved as a matter of routine as your
education progresses. Best to you.

On 8/9/2023 7:17 PM, nero wrote:
> I should like to know the theoric energy in kwh necessary for keeping in air a kg for an hour ...
> It is the problem of all the birds , drones, plains , helicopters.....
> It is the number for calculating the efficienty of the fligth

2nd attempt- the first got lost somewhere somehow.

Generally speaking it is advised an individual achieve communication
skills before progressing to more advanced topics. As stated above
it is clear that you don't know enough to properly state the problem
you're attempting to solve. Stick with the accepted learning sequence
rather than jumping ahead into realms you're not yet capable of
understanding. Don't take this as a putdown, take it as a strong
suggestion that you slow down. The question(s) you're attempting
to ask will probably be resolved as a matter of routine as your
education progresses. Best to you.

nero <oldogf@yahoo.it> wrote:

> I should like to know the theoric energy in kwh necessary for keeping in
> Iair a kg for an hour ... t is the problem of all the birds , drones,
> Iplains , helicopters..... t is the number for calculating the efficienty
> Iof the fligth

You really should do some work on your classical mechanics.
(suspends anti-homework rule for once)

In horizontal flight there are four forces,
Lift Drag, Thrust and Weight.
For steady horizontal flight Thrust must equal Drag,
and Lift must equal Weight.
So their is no theoretical minimum. L/D could be infinite.
For a real wing L/D will be about 10.
(order of magnitude, more for a sailplane, less for a jet fighter)
So to move through the air at speed v requires a power P of v times D.

So the fundamental equation for steady horizontal flight is

v = L/D . P/W, or P = vWD/L

You can take it from there, for practical planes and birds,
if you have an idea about v and W, and L/D.

Your turn,

Jan

PS For much more (then you may want to know)
I can recommend:
The Simple Science of Flight_ From Insects to Jumbo Jets,
by Henk Tennekes.
<https://mitpress.mit.edu/9780262700658/the-simple-science-of-flight/>

It is a delightful, and insightful little book.

Il giorno giovedì 10 agosto 2023 alle 04:49:09 UTC+2 whodat ha scritto:
> On 8/9/2023 7:17 PM, nero wrote:
> > I should like to know the theoric energy in kwh necessary for keeping in air a kg for an hour ...
> > It is the problem of all the birds , drones, plains , helicopters.....
> > It is the number for calculating the efficienty of the fligth
> 2nd attempt- the first got lost somewhere somehow.
> Generally speaking it is advised an individual achieve communication
> skills before progressing to more advanced topics. As stated above
> it is clear that you don't know enough to properly state the problem
> you're attempting to solve. Stick with the accepted learning sequence
> rather than jumping ahead into realms you're not yet capable of
> understanding. Don't take this as a putdown, take it as a strong
> suggestion that you slow down. The question(s) you're attempting
> to ask will probably be resolved as a matter of routine as your
> education progresses. Best to you.
... thanks

Il giorno giovedì 10 agosto 2023 alle 04:49:09 UTC+2 whodat ha scritto:
> On 8/9/2023 7:17 PM, nero wrote:
> > I should like to know the theoric energy in kwh necessary for keeping in air a kg for an hour ...
> > It is the problem of all the birds , drones, plains , helicopters.....
> > It is the number for calculating the efficienty of the fligth
> 2nd attempt- the first got lost somewhere somehow.
> Generally speaking it is advised an individual achieve communication
> skills before progressing to more advanced topics. As stated above
> it is clear that you don't know enough to properly state the problem
> you're attempting to solve. Stick with the accepted learning sequence
> rather than jumping ahead into realms you're not yet capable of
> understanding. Don't take this as a putdown, take it as a strong
> suggestion that you slow down. The question(s) you're attempting
> to ask will probably be resolved as a matter of routine as your
> education progresses. Best to you.
... thanks

Il giorno giovedì 10 agosto 2023 alle 11:37:07 UTC+2 J. J. Lodder ha scritto:
> nero <old...@yahoo.it> wrote:
>
> > I should like to know the theoric energy in kwh necessary for keeping in
> > Iair a kg for an hour ... t is the problem of all the birds , drones,
> > Iplains , helicopters..... t is the number for calculating the efficienty
> > Iof the fligth
>
> You really should do some work on your classical mechanics.
> (suspends anti-homework rule for once)
>
> In horizontal flight there are four forces,
> Lift Drag, Thrust and Weight.
> For steady horizontal flight Thrust must equal Drag,
> and Lift must equal Weight.
> So their is no theoretical minimum. L/D could be infinite.
> For a real wing L/D will be about 10.
> (order of magnitude, more for a sailplane, less for a jet fighter)
> So to move through the air at speed v requires a power P of v times D.
>
> So the fundamental equation for steady horizontal flight is
>
> v = L/D . P/W, or P = vWD/L
>
> You can take it from there, for practical planes and birds,
> if you have an idea about v and W, and L/D.
>
> Your turn,
>
> Jan
>
> PS For much more (then you may want to know)
> I can recommend:
> The Simple Science of Flight_ From Insects to Jumbo Jets,
> by Henk Tennekes.
> <https://mitpress.mit.edu/9780262700658/the-simple-science-of-flight/>
>
> It is a delightful, and insightful little book.
...thanks... your answer was much , but not enough

Il giorno giovedì 10 agosto 2023 alle 11:37:07 UTC+2 J. J. Lodder ha scritto:
> nero <old...@yahoo.it> wrote:
>
> > I should like to know the theoric energy in kwh necessary for keeping in
> > Iair a kg for an hour ... t is the problem of all the birds , drones,
> > Iplains , helicopters..... t is the number for calculating the efficienty
> > Iof the fligth
>
> You really should do some work on your classical mechanics.
> (suspends anti-homework rule for once)
>
> In horizontal flight there are four forces,
> Lift Drag, Thrust and Weight.
> For steady horizontal flight Thrust must equal Drag,
> and Lift must equal Weight.
> So their is no theoretical minimum. L/D could be infinite.
> For a real wing L/D will be about 10.
> (order of magnitude, more for a sailplane, less for a jet fighter)
> So to move through the air at speed v requires a power P of v times D.
>
> So the fundamental equation for steady horizontal flight is
>
> v = L/D . P/W, or P = vWD/L
>
> You can take it from there, for practical planes and birds,
> if you have an idea about v and W, and L/D.
>
> Your turn,
>
> Jan
>
> PS For much more (then you may want to know)
> I can recommend:
> The Simple Science of Flight_ From Insects to Jumbo Jets,
> by Henk Tennekes.
> <https://mitpress.mit.edu/9780262700658/the-simple-science-of-flight/>
>
> It is a delightful, and insightful little book.
... thanks ... your answer was much , but not enough

On 10-Aug-23 10:17 am, nero wrote:
> I should like to know the theoric energy in kwh necessary for keeping in air a kg for an hour ...
> It is the problem of all the birds , drones, plains , helicopters.....
> It is the number for calculating the efficienty of the fligth

The answer is that there is no theoretical minimum. It's an engineering
problem that seeks to balance structural weight, friction, generation of
turbulence resulting in drag, and so on.

Sylvia.

nero <oldogf@yahoo.it> wrote:

> Il giorno giovedì 10 agosto 2023 alle 11:37:07 UTC+2 J. J. Lodder ha scritto:
> > nero <old...@yahoo.it> wrote:
> >
> > > I should like to know the theoric energy in kwh necessary for keeping in
> > > Iair a kg for an hour ... t is the problem of all the birds , drones,
> > > Iplains , helicopters..... t is the number for calculating the efficienty
> > > Iof the fligth
> >
> > You really should do some work on your classical mechanics.
> > (suspends anti-homework rule for once)
> >
> > In horizontal flight there are four forces,
> > Lift Drag, Thrust and Weight.
> > For steady horizontal flight Thrust must equal Drag,
> > and Lift must equal Weight.
> > So their is no theoretical minimum. L/D could be infinite.
> > For a real wing L/D will be about 10.
> > (order of magnitude, more for a sailplane, less for a jet fighter)
> > So to move through the air at speed v requires a power P of v times D.
> >
> > So the fundamental equation for steady horizontal flight is
> >
> > v = L/D . P/W, or P = vWD/L
> >
> > You can take it from there, for practical planes and birds,
> > if you have an idea about v and W, and L/D.
> >
> > Your turn,
> >
> > Jan
> >
> > PS For much more (then you may want to know)
> > I can recommend:
> > The Simple Science of Flight_ From Insects to Jumbo Jets,
> > by Henk Tennekes.
> > <https://mitpress.mit.edu/9780262700658/the-simple-science-of-flight/>
> >
> > It is a delightful, and insightful little book.
> ..thanks... your answer was much , but not enough

Sorry, homework help hour is over.
Try reading Tennekes for yourself,
to get started.
But you really do need elementary Newtonian mechanics first,

Jan

Sylvia Else <sylvia@email.invalid> wrote:

> On 10-Aug-23 10:17 am, nero wrote:
> > I should like to know the theoric energy in kwh necessary for keeping in
> > Iair a kg for an hour ... t is the problem of all the birds , drones,
> > Iplains , helicopters..... t is the number for calculating the
> > Iefficienty of the fligth
>
> The answer is that there is no theoretical minimum. It's an engineering
> problem that seeks to balance structural weight, friction, generation of
> turbulence resulting in drag, and so on.

The theoretical minimum must be for infinite span wings,
flying at zero velocity....

Jan

On Friday, August 11, 2023 at 5:53:57 AM UTC-5, J. J. Lodder wrote:
> Sylvia Else <syl...@email.invalid> wrote:
>
> > On 10-Aug-23 10:17 am, nero wrote:
> > > I should like to know the theoric energy in kwh necessary for keeping in
> > > Iair a kg for an hour ... t is the problem of all the birds , drones,
> > > Iplains , helicopters..... t is the number for calculating the
> > > Iefficienty of the fligth
> >
> > The answer is that there is no theoretical minimum. It's an engineering
> > problem that seeks to balance structural weight, friction, generation of
> > turbulence resulting in drag, and so on.
> The theoretical minimum must be for infinite span wings,
> flying at zero velocity....

How about large lightweight wings with volume
sufficiently large that their buoyancy keeps the plane
afloat? Maybe fill them with helium? :-)

On Friday, August 11, 2023 at 11:02:25 AM UTC-7, Prokaryotic Capase Homolog wrote:
> On Friday, August 11, 2023 at 5:53:57 AM UTC-5, J. J. Lodder wrote:
> > Sylvia Else <syl...@email.invalid> wrote:
> >
> > > On 10-Aug-23 10:17 am, nero wrote:
> > > > I should like to know the theoric energy in kwh necessary for keeping in
> > > > Iair a kg for an hour ... t is the problem of all the birds , drones,
> > > > Iplains , helicopters..... t is the number for calculating the
> > > > Iefficienty of the fligth
> > >
> > > The answer is that there is no theoretical minimum. It's an engineering
> > > problem that seeks to balance structural weight, friction, generation of
> > > turbulence resulting in drag, and so on.
> > The theoretical minimum must be for infinite span wings,
> > flying at zero velocity....
> How about large lightweight wings with volume
> sufficiently large that their buoyancy keeps the plane
> afloat? Maybe fill them with helium? :-)
And how about explaining the lift of the standard airfoil in inverted flight in terms of the Bernoulli theory of lift, sans Newton.

Prokaryotic Capase Homolog <prokaryotic.caspase.homolog@gmail.com>
wrote:

> On Friday, August 11, 2023 at 5:53:57?AM UTC-5, J. J. Lodder wrote:
> > Sylvia Else <syl...@email.invalid> wrote:
> >
> > > On 10-Aug-23 10:17 am, nero wrote:
> > > > I should like to know the theoric energy in kwh necessary for keeping in
> > > > Iair a kg for an hour ... t is the problem of all the birds , drones,
> > > > Iplains , helicopters..... t is the number for calculating the
> > > > Iefficienty of the fligth
> > >
> > > The answer is that there is no theoretical minimum. It's an engineering
> > > problem that seeks to balance structural weight, friction, generation of
> > > turbulence resulting in drag, and so on.
> > The theoretical minimum must be for infinite span wings,
> > flying at zero velocity....
>
> How about large lightweight wings with volume
> sufficiently large that their buoyancy keeps the plane
> afloat? Maybe fill them with helium? :-)

He is asking about flight, not balloons.
The best attempts so far are those human powered planes,
like the 'Gossamer Albatros'.
Typical wingspan: order 30 m, typical weight 100 kg (loaded)
Powerplant: 1 human at a perhaps 300 W,
for about 20 km/h cruising speed.
Endurance: a few hours at best.

They are museum pieces, and it is unlikely that those values
will ever be improved upon,

Jan

Jan

patdolan <patdolan@comcast.net> wrote:

> On Friday, August 11, 2023 at 11:02:25?AM UTC-7, Prokaryotic Capase Homolog:
> > On Friday, August 11, 2023 at 5:53:57?AM UTC-5, J. J. Lodder wrote:
> > > Sylvia Else <syl...@email.invalid> wrote:
> > >
> > > > On 10-Aug-23 10:17 am, nero wrote:
> > > > > I should like to know the theoric energy in kwh necessary for
> > > > > Ikeeping in air a kg for an hour ... t is the problem of all the
> > > > > Ibirds , drones, plains , helicopters..... t is the number for
> > > > > Icalculating the efficienty of the fligth
> > > >
> > > > The answer is that there is no theoretical minimum. It's an
> > > > engineering problem that seeks to balance structural weight,
> > > > friction, generation of turbulence resulting in drag, and so on.
> > > The theoretical minimum must be for infinite span wings,
> > > flying at zero velocity....
> > How about large lightweight wings with volume
> > sufficiently large that their buoyancy keeps the plane
> > afloat? Maybe fill them with helium? :-)
> And how about explaining the lift of the standard airfoil in inverted
> flight in terms of the Bernoulli theory of lift, sans Newton.

Do your own homework,

Jan

On Friday, August 11, 2023 at 1:54:54 PM UTC-5, J. J. Lodder wrote:
> Prokaryotic Capase Homolog <prokaryotic.c...@gmail.com>

> > How about large lightweight wings with volume
> > sufficiently large that their buoyancy keeps the plane
> > afloat? Maybe fill them with helium? :-)
> He is asking about flight, not balloons.

Of course that is what he *meant*.
But the OP terminated his set of examples with ellipses:
"It is the problem of all the birds , drones, plains , helicopters....."

Given the presence of ellipses, I believe that I am free
to *intentionally misinterpret* his question any way that
I want to. :-)

Prokaryotic Capase Homolog <prokaryotic.caspase.homolog@gmail.com>
wrote:

> On Friday, August 11, 2023 at 1:54:54?PM UTC-5, J. J. Lodder wrote:
> > Prokaryotic Capase Homolog <prokaryotic.c...@gmail.com>
>
> > > How about large lightweight wings with volume
> > > sufficiently large that their buoyancy keeps the plane
> > > afloat? Maybe fill them with helium? :-)
> > He is asking about flight, not balloons.
>
> Of course that is what he *meant*.
> But the OP terminated his set of examples with ellipses:
> "It is the problem of all the birds , drones, plains , helicopters....."
>
> Given the presence of ellipses, I believe that I am free
> to *intentionally misinterpret* his question any way that
> I want to. :-)

OK, so next proceed to find out how many kWh that helium costs,

Jan

On August 10, J. J. Lodder wrote:
> In horizontal flight there are four forces,
> Lift Drag, Thrust and Weight.
> For steady horizontal flight Thrust must equal Drag,
> and Lift must equal Weight.
> L/D could be infinite.
> For a real wing L/D will be about 10.
> So to move through the air at speed v requires a power P of v times D.
> So the fundamental equation for steady horizontal flight is
> v = L/D . P/W, or P = vWD/L

You forgot buoyancy B. The atmosphere is liquid.

If you pump air into a plane at high pressure, and heat
to high temperature, it will float, no fuel needed.
Hydrogen, even better -

--
Rich

On 8/12/2023 2:01 PM, RichD wrote:
> On August 10, J. J. Lodder wrote:
>> In horizontal flight there are four forces,
>> Lift Drag, Thrust and Weight.
>> For steady horizontal flight Thrust must equal Drag,
>> and Lift must equal Weight.
>> L/D could be infinite.
>> For a real wing L/D will be about 10.
>> So to move through the air at speed v requires a power P of v times D.
>> So the fundamental equation for steady horizontal flight is
>> v = L/D . P/W, or P = vWD/L
>
> You forgot buoyancy B. The atmosphere is liquid.

Liquids are not compressible. End of story.

> If you pump air into a plane at high pressure, and heat
> to high temperature, it will float, no fuel needed.

Bzzzzzzttttttt! Even if you remove the atmosphere completely
from any modern airplane it will remain heavier than air. Floating
requires weight less than the amount of air displaced by the plane.

I'm shocked by this posting, worse even than Laurence's ignorance
of the basics.

> Hydrogen, even better -

Nope.

On 8/12/2023 3:16 PM, whodat wrote:
> On 8/12/2023 2:01 PM, RichD wrote:
>> On August 10, J. J. Lodder wrote:
>>> In horizontal flight there are four forces,
>>> Lift Drag, Thrust and Weight.
>>> For steady horizontal flight Thrust must equal Drag,
>>> and Lift must equal Weight.
>>> L/D could be infinite.
>>> For a real wing L/D will be about 10.
>>> So to move through the air at speed v requires a power P of v times D.
>>> So the fundamental equation for steady horizontal flight is
>>> v = L/D . P/W, or P = vWD/L
>>
>> You forgot buoyancy B.  The atmosphere is liquid.
>
> Liquids are not compressible. End of story.

I'm guessing the word he's looking for is "fluid".

I think it's best to consider any buoyancy as a modification to the weight.
>
>> If you pump air into a plane at high pressure, and heat
>> to high temperature, it will float, no fuel needed.
>
> Bzzzzzzttttttt! Even if you remove the atmosphere completely
> from any modern airplane it will remain heavier than air. Floating
> requires weight less than the amount of air displaced by the plane.
>
> I'm shocked by this posting, worse even than Laurence's ignorance
> of the basics.

It requires a large volume to get the total weight down to zero.
Consider a zeppelin like the Hindenburg and the size of its passenger
compartment.
>
>> Hydrogen, even better -
>
> Nope.
>

whodat <whodaat@void.nowgre.com> wrote:

> On 8/12/2023 2:01 PM, RichD wrote:
> > On August 10, J. J. Lodder wrote:
> >> In horizontal flight there are four forces,
> >> Lift Drag, Thrust and Weight.
> >> For steady horizontal flight Thrust must equal Drag,
> >> and Lift must equal Weight.
> >> L/D could be infinite.
> >> For a real wing L/D will be about 10.
> >> So to move through the air at speed v requires a power P of v times D.
> >> So the fundamental equation for steady horizontal flight is
> >> v = L/D . P/W, or P = vWD/L
> >
> > You forgot buoyancy B. The atmosphere is liquid.
>
> Liquids are not compressible. End of story.
>
> > If you pump air into a plane at high pressure, and heat
> > to high temperature, it will float, no fuel needed.
>
> Bzzzzzzttttttt! Even if you remove the atmosphere completely
> from any modern airplane it will remain heavier than air.
> Floating requires weight less than the amount of air displaced by the
> plane.
>
> I'm shocked by this posting, worse even than Laurence's ignorance
> of the basics.

Indeed. But...
Once upon a time, long ago, lived the greatest inventor of all time.
His name was Daedalus, and he published a weekly column
in New Scientist, and later in Nature.

One of his great inventions was the vacuum balloon.
It had a 'double umbrella' structure.
With the latest in strong materials,
and if deployed at high altitude to begin with,
it might be actually possible to build one.
And with a solar powered small vacuum pump to undo the leakage
it would really float forever. (unkike helium filled ones)
(they are still working on it, at DREADCO)

Jan

RichD <r_delaney2001@yahoo.com> wrote:

> On August 10, J. J. Lodder wrote:
> > In horizontal flight there are four forces,
> > Lift Drag, Thrust and Weight.
> > For steady horizontal flight Thrust must equal Drag,
> > and Lift must equal Weight.
> > L/D could be infinite.
> > For a real wing L/D will be about 10.
> > So to move through the air at speed v requires a power P of v times D.
> > So the fundamental equation for steady horizontal flight is
> > v = L/D . P/W, or P = vWD/L
>
> You forgot buoyancy B. The atmosphere is liquid.

Bzzzzzzttttttt!
The weight in the above is the -effective weight in air-.
The equation above does also cover balloons and Zeppelins.
It simplifies to T = D and v = P/D for Zeppelins, (at incidence = 0)
and even further to v = 0 for unpowered balloons.

And you are confusing 'liquid' and 'fluid'.

> If you pump air into a plane at high pressure, and heat
> to high temperature, it will float, no fuel needed.
> Hydrogen, even better -

You really need to think about this again,

Jan

Il giorno domenica 13 agosto 2023 alle 10:34:54 UTC+2 J. J. Lodder ha scritto:
> RichD <r_dela...@yahoo.com> wrote:
>
> > On August 10, J. J. Lodder wrote:
> > > In horizontal flight there are four forces,
> > > Lift Drag, Thrust and Weight.
> > > For steady horizontal flight Thrust must equal Drag,
> > > and Lift must equal Weight.
> > > L/D could be infinite.
> > > For a real wing L/D will be about 10.
> > > So to move through the air at speed v requires a power P of v times D.
> > > So the fundamental equation for steady horizontal flight is
> > > v = L/D . P/W, or P = vWD/L
> >
> > You forgot buoyancy B. The atmosphere is liquid.
> Bzzzzzzttttttt!
> The weight in the above is the -effective weight in air-.
> The equation above does also cover balloons and Zeppelins.
> It simplifies to T = D and v = P/D for Zeppelins, (at incidence = 0)
> and even further to v = 0 for unpowered balloons.
>
> And you are confusing 'liquid' and 'fluid'.
> > If you pump air into a plane at high pressure, and heat
> > to high temperature, it will float, no fuel needed.
> > Hydrogen, even better -
> You really need to think about this again,
>
> Jan
dear friends... relatively to the theoric efficiency against yhe gravitational strength, it is a good example of the efficiency the Solar Impulse 2 of Piccard (50%?) , the helicopters (10-20%?) ; the drones less than 1%(?)..
the aim of the post is to find the theoric number of kwh for kg , using a logic theoric formulation ...

nero <oldogf@yahoo.it> wrote:

> Il giorno domenica 13 agosto 2023 alle 10:34:54 UTC+2 J. J. Lodder ha scritto:
> > RichD <r_dela...@yahoo.com> wrote:
> >
> > > On August 10, J. J. Lodder wrote:
> > > > In horizontal flight there are four forces,
> > > > Lift Drag, Thrust and Weight.
> > > > For steady horizontal flight Thrust must equal Drag,
> > > > and Lift must equal Weight.
> > > > L/D could be infinite.
> > > > For a real wing L/D will be about 10.
> > > > So to move through the air at speed v requires a power P of v times D.
> > > > So the fundamental equation for steady horizontal flight is
> > > > v = L/D . P/W, or P = vWD/L
> > >
> > > You forgot buoyancy B. The atmosphere is liquid.
> > Bzzzzzzttttttt!
> > The weight in the above is the -effective weight in air-.
> > The equation above does also cover balloons and Zeppelins.
> > It simplifies to T = D and v = P/D for Zeppelins, (at incidence = 0)
> > and even further to v = 0 for unpowered balloons.
> >
> > And you are confusing 'liquid' and 'fluid'.
> > > If you pump air into a plane at high pressure, and heat
> > > to high temperature, it will float, no fuel needed.
> > > Hydrogen, even better -
> > You really need to think about this again,
> >
> > Jan
> dear friends... relatively to the theoric efficiency against yhe
> gravitational strength, it is a good example of the efficiency the Solar
> Impulse 2 of Piccard (50%?) , the helicopters (10-20%?) ; the drones less
> than 1%(?).. the aim of the post is to find the theoric number of kwh for
> kg , using a logic theoric formulation ...

Sorry, homework help hour is over. No more spoon feeding.
You are on your own until you show at least some willingness
to learn something for yourself.
(hint: the answer has already been given)

Jan

On August 13, J. J. Lodder wrote:
> > > In horizontal flight there are four forces,
> > > Lift Drag, Thrust and Weight.
> > > For steady horizontal flight Thrust must equal Drag,
> > > and Lift must equal Weight.
> > > For a real wing L/D will be about 10.
> > > So to move through the air at speed v requires a power P of v times D.
> > > So the fundamental equation for steady horizontal flight is
> > > v = L/D . P/W, or P = vWD/L
>
>> You forgot buoyancy B. The atmosphere is liquid.
>
> Bzzzzzzttttttt!
> The weight in the above is the -effective weight in air-.
> The equation above does also cover balloons and Zeppelins.
> It simplifies to T = D and v = P/D for Zeppelins, (at incidence = 0)
> And you are confusing 'liquid' and 'fluid'.

Aluminum is heavier than water, it sinks. But if you pump air into
a tank, it becomes buoyant. Ask a scuba diver, they're
experts on fluid mechanics, their lives depend on it.

Ditto with the atmosphere -

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Rich