On 07/01/2013 05:24 PM, Sidsel & Svein Johnsen wrote:
>> 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.
> 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.
> 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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