Re: atmospheric density effects on airfoils

[Stubby]

TravisRogers wrote:
> Hi All,
>
> The density of air changes notably with changes in temperature which
> results in differences in lift to an airfoil. After putting on my mad
> scientist cap, I got to wondering -- are there any other methods of
> altering the density of air? Perhaps using radiation of a particular
> wavelength (from radio to gamma) or other perhaps other methods?
>
> In particular, I'm wondering if it is possible to change the density of a
> specific predetermined volume of the atmosphere. The idea is to create an
> area of the atmosphere that is far too thin or far too thick to be
> compatible with an airfoil, thus denying the area to (terrorist) aircraft.
>
> This whole thing sounds pretty far out there but it's amusing to think
> about. Any thoughts?
>
>
You could do something like release an enormous volume of hydrogen, but
it would be difficult to contain in a specific area.

To increase the density, you can use water vapor. Or pollen. Because
lift is proportional to mass flow, you will be helping the enemy.
However, you might want to assist a plane which is running low on fuel
by making its wings more effective for a short time.

I cut back to one newsgroup for this post. There's no reason to
broadcast this nonsense.

[Roy Smith]

Stubby > wrote:
> To increase the density, you can use water vapor.

Adding water vapor will decrease density.

[Stubby]

Roy Smith wrote:

> Stubby > wrote:
>
>>To increase the density, you can use water vapor.
>
>
> Adding water vapor will decrease density.
Right. Sorry about that.
Water vapor is molecular weight 18. Average "air" is 29.

[Al]

Hello,

The changes in density are pretty minor with temp, more with altitude.
The airfoil
doesn't really feel the change, but if an airplane going 100mph climbs into
thinner air,
the airplane feels less drag so it speeds up. At the higher speed, the quick
thin air feels
just like the thicker slower air. A lear jet that is doing 250 kts at sea
level, is really
going about 250kts. The same airplane showing 250kts on the airspeed
indicator at 45,000
feet is actually moving about 450kts.

Al CFIAMI



"TravisRogers" > wrote in message
...
> Hi All,
>
> The density of air changes notably with changes in temperature which
> results in differences in lift to an airfoil. After putting on my mad
> scientist cap, I got to wondering -- are there any other methods of
> altering the density of air? Perhaps using radiation of a particular
> wavelength (from radio to gamma) or other perhaps other methods?
>
> In particular, I'm wondering if it is possible to change the density of a
> specific predetermined volume of the atmosphere. The idea is to create an
> area of the atmosphere that is far too thin or far too thick to be
> compatible with an airfoil, thus denying the area to (terrorist) aircraft.
>
> This whole thing sounds pretty far out there but it's amusing to think
> about. Any thoughts?
>
>

[Juan Jimenez]

If I remember correctly, there has been some research done as to the effects
of a strong magnetic field at the forward end of an aircraft to decrease
drag. I don't know how it works, but I remember reading the concept was
being considered to reduce heat on the hypersonic aircraft airframes.

"TravisRogers" > wrote in message
...
> Hi All,
>
> The density of air changes notably with changes in temperature which
> results in differences in lift to an airfoil. After putting on my mad
> scientist cap, I got to wondering -- are there any other methods of
> altering the density of air? Perhaps using radiation of a particular
> wavelength (from radio to gamma) or other perhaps other methods?
>
> In particular, I'm wondering if it is possible to change the density of a
> specific predetermined volume of the atmosphere. The idea is to create an
> area of the atmosphere that is far too thin or far too thick to be
> compatible with an airfoil, thus denying the area to (terrorist) aircraft.
>
> This whole thing sounds pretty far out there but it's amusing to think
> about. Any thoughts?
>
>

[Brian Whatcott]

A laser beam providing a thermal expansion wave ahead.

Brian Whatcott Altus, OK

On Thu, 23 Jun 2005 21:20:33 -0400, "Juan Jimenez" >
wrote:

>If I remember correctly, there has been some research done as to the effects
>of a strong magnetic field at the forward end of an aircraft to decrease
>drag. I don't know how it works, but I remember reading the concept was
>being considered to reduce heat on the hypersonic aircraft airframes.
>
>"TravisRogers" > wrote in message
...
>> Hi All,
>>
>> The density of air changes notably with changes in temperature which
>> results in differences in lift to an airfoil. After putting on my mad
>> scientist cap, I got to wondering -- are there any other methods of
>> altering the density of air? Perhaps using radiation of a particular
>> wavelength (from radio to gamma) or other perhaps other methods?
>>
>> In particular, I'm wondering if it is possible to change the density of a
>> specific predetermined volume of the atmosphere. The idea is to create an
>> area of the atmosphere that is far too thin or far too thick to be
>> compatible with an airfoil, thus denying the area to (terrorist) aircraft.
>>
>> This whole thing sounds pretty far out there but it's amusing to think
>> about. Any thoughts?
>>
>>
>