Here's a question for the trolls and flight simmers

glory be, what can the answer be?

On Jun 25, 10:46 am, alexy wrote:
Stealth Pilot wrote:
On Wed, 25 Jun 2008 12:43:21 GMT, "Mike" wrote:

"Stealth Pilot" wrote in message
. ..

I know we beat on you guys a lot here but here is a serious question
for you to explore.

scenario: you are flying along on a bright sunny day with no cloud
cover. your wingspan is about 20 ft, fuselage length 14ft and
tailplane about 8ft span. your altitude is 4,500ft.

you look down below you in the exact opposite direction to the sun.

what do you see below you scooting along the ground below you?
is it a sharply defined shadow of your aircraft?
a fuzzy indistinct shadow of your aeroplane?
or what?

it is quite distinct and you can pick it from nearly a mile away.

....now pilots dont tell them. these guys are actually quite
intelligent but not in' hands on' aviation matters. they should be
able to work this out.

In the grand scheme of "hands on aviation matters", how many beans are in
this hill?

I notice that there are no attempts at an answer.

Well, you directed the question to flight simmers and trolls. If you
want to open it up to non-pilot lurkers, I'll take a guess. Assuming
you will reveal the correct answer and explain it.
--
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.

wrote:


On Jun 25, 10:46 am, alexy wrote:
Stealth Pilot wrote:
On Wed, 25 Jun 2008 12:43:21 GMT, "Mike" wrote:

"Stealth Pilot" wrote in message
. ..

I know we beat on you guys a lot here but here is a serious question
for you to explore.

scenario: you are flying along on a bright sunny day with no cloud
cover. your wingspan is about 20 ft, fuselage length 14ft and
tailplane about 8ft span. your altitude is 4,500ft.

you look down below you in the exact opposite direction to the sun.

what do you see below you scooting along the ground below you?
is it a sharply defined shadow of your aircraft?
a fuzzy indistinct shadow of your aeroplane?
or what?

it is quite distinct and you can pick it from nearly a mile away.

....now pilots dont tell them. these guys are actually quite
intelligent but not in' hands on' aviation matters. they should be
able to work this out.

In the grand scheme of "hands on aviation matters", how many beans are in
this hill?

I notice that there are no attempts at an answer.

Well, you directed the question to flight simmers and trolls. If you
want to open it up to non-pilot lurkers, I'll take a guess. Assuming
you will reveal the correct answer and explain it.

glory be, what can the answer be?


My guess is that since the plane will subtend a much smaller angle
than the sun, there would be no noticeable shadow. My guess is a
"halo" around where the shadow would be, caused by diffraction, Since
most of the edges tend to be inline with the plane's axis or
perpendicular to it, it seems that this halo might be somewhat
brighter on those two axes, but I wonder if that would be noticeable.
The halo might have a slightly bluish cast, since the red end of the
spectrum would get diffracted more, and being over a larger area would
be not as bright.

So, what's the real answer?
--
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.

On Wed, 25 Jun 2008 15:05:19 -0400, alexy wrote:

wrote:



Well, you directed the question to flight simmers and trolls. If you
want to open it up to non-pilot lurkers, I'll take a guess. Assuming
you will reveal the correct answer and explain it.

glory be, what can the answer be?


My guess is that since the plane will subtend a much smaller angle
than the sun, there would be no noticeable shadow. My guess is a
"halo" around where the shadow would be, caused by diffraction, Since
most of the edges tend to be inline with the plane's axis or
perpendicular to it, it seems that this halo might be somewhat
brighter on those two axes, but I wonder if that would be noticeable.
The halo might have a slightly bluish cast, since the red end of the
spectrum would get diffracted more, and being over a larger area would
be not as bright.

So, what's the real answer?


sitting on the ground with the sun about 93 million miles away the
aircraft casts a sharp shadow on the ground.

at 500ft altitude the aircraft is 500ft closer to the sun than the
previous 93 million miles, which is next to no change at all, so there
will be very little change to the shadow you'd think. but there is. at
500ft the aircraft shadow is a very indistinct blur surrounded by a
halo of bright light.

at 4,500ft (the original question) the aircraft has no shadow at all
but at the sub solar point (were you'd think the shadow should be)
there is a distinct bright area tracking along under the aircraft.

for thirty years this quietly puzzled me. it is a fact that aircraft
at altitude have no shadow. below them tracking along the ground is a
bright spot of light.

the reference I gave gives details of some original work by Fresnel
which proposed that light passing beside a gravitational mass should
be bent slightly by the mass and behind the body there should be a
bright spot. this seems to me to be the explanation for the absense of
the shadow. the mass of the aircraft acts as a gravitational lens and
this causes the bright spot.

the reason I asked the question was to point out that simulators work
on a simplified model of the reality that real pilots are exposed to.
people like mxsmanic seem utterly oblivious to the fact that their
exposure to the simulator will never give them competent knowledge
because all they are exposed to is a simplified model of reality. it
is only exposure to the actual reality that will allow you to achieve
competent knowledge.

if simulators dont get something as simple as the aircraft's shadow
right can you trust that anything else they show you is right?

Stealth Pilot

I'm sorry, I didn't see this post until now. One of the
fondest memories of my first solo was seeing my own
shadow below. I guess my attention was elsewhere while
I had the CFI in the cockpit with me.
Lou

Lou wrote:
I'm sorry, I didn't see this post until now. One of the
fondest memories of my first solo was seeing my own
shadow below.

My strongest memories were how the plane LEPT off the surface with 200
less pounds and more rearward GC, and remembering on downwind that I HAD
to land the plane with no reminders or comments from the CFI.

My PP CFI was a "master of distraction" type of chatty guy. He would
continually yak on about things that had nothing to do with flying. I
also noticed how peaceful solo flight was! G

My PP CFI was a "master of distraction" type of chatty guy. He would
continually yak on about things that had nothing to do with flying. I
also noticed how peaceful solo flight was! G

That's funny, while reading this I was thinking the same thing. My CFI
kept
talking about things he did over the weekend, what did I do etc. I
guess
it worked.
Lou

Lou wrote:
My PP CFI was a "master of distraction" type of chatty guy. He would
continually yak on about things that had nothing to do with flying. I
also noticed how peaceful solo flight was! G

That's funny, while reading this I was thinking the same thing. My CFI
kept
talking about things he did over the weekend, what did I do etc. I
guess
it worked.

It did!

All the same stuff non-flying pax talk about that can easily draw you in
and away from flying.

The quiet on the first solo, without him yakkin' away, was soooooooooooo
noticeable! G

On Jun 29, 9:59*am, Lou wrote:
I'm sorry, I didn't see this post until now. One of the
fondest memories of my first solo was seeing my own
shadow below. I guess my attention was elsewhere while
I had the CFI in the cockpit with me.
* * * *Lou

I agree. Right up there with my first Flightaware track was seeing my
airplane shadow the first time. There are some things that really
point out that you are now different than most of the population
because you can fly a plane.

In article ,
Stealth Pilot wrote:

at 4,500ft (the original question) the aircraft has no shadow at all
but at the sub solar point (were you'd think the shadow should be)
there is a distinct bright area tracking along under the aircraft.

for thirty years this quietly puzzled me. it is a fact that aircraft
at altitude have no shadow. below them tracking along the ground is a
bright spot of light.

the reference I gave gives details of some original work by Fresnel
which proposed that light passing beside a gravitational mass should
be bent slightly by the mass and behind the body there should be a
bright spot. this seems to me to be the explanation for the absense of
the shadow. the mass of the aircraft acts as a gravitational lens and
this causes the bright spot.

Poisson spot, Spot of Arago, Keller edge waves. Very much doubt
gravitational bending of light is involved.

On Sun, 29 Jun 2008 08:24:13 -0700, AES wrote:

In article ,
Stealth Pilot wrote:

at 4,500ft (the original question) the aircraft has no shadow at all
but at the sub solar point (were you'd think the shadow should be)
there is a distinct bright area tracking along under the aircraft.

for thirty years this quietly puzzled me. it is a fact that aircraft
at altitude have no shadow. below them tracking along the ground is a
bright spot of light.

the reference I gave gives details of some original work by Fresnel
which proposed that light passing beside a gravitational mass should
be bent slightly by the mass and behind the body there should be a
bright spot. this seems to me to be the explanation for the absense of
the shadow. the mass of the aircraft acts as a gravitational lens and
this causes the bright spot.

Poisson spot, Spot of Arago, Keller edge waves. Very much doubt
gravitational bending of light is involved.

I looked up explanations and graphics of these effects.
the poissons spot demo looks entirely different from what I see.

I'm still happy with my explanation.

Stealth Pilot