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sidsel.svein(at)oslo.onli
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 Posted: Mon Jul 01, 2013 7:24 am Post subject: SV: SV: Re: wing lift/drag pins |
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Frans,
Our postings are crossing a little, but I think the below covers also your
last one:
| Quote: | > A glider is
> "propelled" by the forward - in the direction of flight - component of
> the aircraft's WEIGHT only.
Ok, got it. But without wings (but still with the majority of the
weight) will the glider still be propelled forwards? I guess not.
Again: What is meant by "forward"? Without wings, the glider will still be
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propelled forwards, and still by gravitational force. Unfortunately for the
pilot, however, "forward" now means more or less vertical towards the ground
.........
| Quote: | Then what exactly is exercising a forward pulling force on the glider's
fuselage? The fuselage has only drag. So something must be pulling it
forward.
I may be stating the obvious, but a glider is always going down, or rather
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gliding down - down relative to the air mass through which it moves. If the
air mass is moving upwards (thermals) faster than the glider moves downwards
through that air mass, the glider climbs relative to the ground even though
it goes down relative to the air mass. All the time, it is the gravity that
causes it to move, and movement through the air creates lift (if the wings
are still on), so that the glider does not fall like a stone through the
surrounding air mass. When the total drag on the glider equals the
gravity's component in the direction of flight, the glider does not
accelerate any more, it has reached constant speed.
Same thing with an airplane with engine, if the engine quits. As long as
the engine works, though, and we fly level, the engine gives enough pull to
equal the total drag, so that we don't need any assistance by the gravity to
create speed. At level flight, the lift and the down force by the
stabilizer are vertical. Gravity is always vertical. I.e. no fore-or-aft
force component from any of these three forces. Only drag, which equals
propeller pull at constant speed.
Regards,
Svein
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raimo.toivio(at)rwm.fi
Guest
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| Posted: Mon Jul 01, 2013 8:23 am Post subject: SV: SV: Re: wing lift/drag pins |
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| Quote: | > A glider is
> "propelled" by the forward - in the direction
> of flight - component of
> the aircraft's WEIGHT only.
|
And that´s why they (gliders) obviously fill also
sometimes their watertanks - to get more load, to
feed gravity and to get speed?
Cheers, Raimo
-----Alkuperäinen viesti-----
From: Sidsel & Svein Johnsen
Sent: Monday, July 01, 2013 6:24 PM
To: europa-list(at)matronics.com
Subject: SV: SV: Re: wing lift/drag
pins
Johnsen" <sidsel.svein(at)oslo.online.no>
Frans,
Our postings are crossing a little, but I think
the below covers also your
last one:
| Quote: | > A glider is
> "propelled" by the forward - in the direction
> of flight - component of
> the aircraft's WEIGHT only.
Ok, got it. But without wings (but still with
the majority of the
weight) will the glider still be propelled
forwards? I guess not.
Again: What is meant by "forward"? Without
|
wings, the glider will still be
propelled forwards, and still by gravitational
force. Unfortunately for the
pilot, however, "forward" now means more or less
vertical towards the ground
.........
| Quote: | Then what exactly is exercising a forward
pulling force on the glider's
fuselage? The fuselage has only drag. So
something must be pulling it
forward.
I may be stating the obvious, but a glider is
|
always going down, or rather
gliding down - down relative to the air mass
through which it moves. If the
air mass is moving upwards (thermals) faster than
the glider moves downwards
through that air mass, the glider climbs relative
to the ground even though
it goes down relative to the air mass. All the
time, it is the gravity that
causes it to move, and movement through the air
creates lift (if the wings
are still on), so that the glider does not fall
like a stone through the
surrounding air mass. When the total drag on the
glider equals the
gravity's component in the direction of flight,
the glider does not
accelerate any more, it has reached constant
speed.
Same thing with an airplane with engine, if the
engine quits. As long as
the engine works, though, and we fly level, the
engine gives enough pull to
equal the total drag, so that we don't need any
assistance by the gravity to
create speed. At level flight, the lift and the
down force by the
stabilizer are vertical. Gravity is always
vertical. I.e. no fore-or-aft
force component from any of these three forces.
Only drag, which equals
propeller pull at constant speed.
Regards,
Svein
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frans(at)privatepilots.nl
Guest
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| Posted: Mon Jul 01, 2013 8:49 am Post subject: SV: SV: Re: wing lift/drag pins |
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On 07/01/2013 05:24 PM, Sidsel & Svein Johnsen wrote:
| Quote: | > Then what exactly is exercising a forward pulling force on the glider's
> fuselage? The fuselage has only drag. So something must be pulling it
> forward.
>
I may be stating the obvious, but a glider is always going down,
|
I guess it is also obvious that it is going down much quicker without
the wings, and with less forward velocity.
So the question remains, if the fuselage without wings has a lower
forward speed than a fuselage with wings, can't we just say that this
means that the wings are pulling the fuselage forwards? No way that the
fuselage itself will maintain a forward speed of 100 knots or so, the
drag is quite substantial, so something is pulling it forward against
the drag. And in the few examples where the wings detached during
flight, it is indeed observed that the wings fold forwards.
The wings MUST BE pulling the fuselage forwards, because the fuselage
would never do this by itself. I can't see how one could argue against that.
| Quote: | All the time, it is the gravity that
causes it to move,
|
Yes, gravity is providing the energy that makes it happen. No doubt
about that. But this is something else than saying that the wings play
no role in it. Sure the wings play a role in it: they counter partly the
gravity and redirect the energy to propel the aircraft forward.
| Quote: | Same thing with an airplane with engine, if the engine quits. As long as
the engine works, though, and we fly level, the engine gives enough pull to
equal the total drag,
|
The engine provides extra energy, so we don't loose altitude while
"going down".
Frans
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