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Search: Posts Made By: awblain
Showing results 1 to 13 of 13
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Forum: Tech Log
3rd Dec 2012, 18:37
Replies: 388
Views: 99,508
Posted By awblain

Owain, I think your baulked flow beneath...

Owain,

I think your baulked flow beneath the wing picture, where the wing is within a fraction of a chord distance of the ground (Fig 4 of your diagram) is effectively describing a sort of...
Forum: Tech Log
3rd Dec 2012, 17:40
Replies: 388
Views: 99,508
Posted By awblain

Lyman, Lift is equal to the net rate of...

Lyman,

Lift is equal to the net rate of change in momentum of the air in the downwards direction as it flows by the wing.

On entering ground effect, `upwash' may increase in some places,...
Forum: Tech Log
3rd Dec 2012, 16:59
Replies: 388
Views: 99,508
Posted By awblain

Downwash/Flirting

Owain,

To the first quote: I'd reply that Ms 39's explanation that there's `more upwash' isn't right, as there is in fact more downwash, or else there would not be more lift.

To the second...
Forum: Tech Log
3rd Dec 2012, 14:33
Replies: 388
Views: 99,508
Posted By awblain

Ground effect & downwash?

If you have less "downwash", I suggest you would have less lift, not more, from Newton's second law - less change of downward momentum to the air, less upward force on the wing.

How's this for...
Forum: Tech Log
19th Nov 2012, 21:29
Replies: 388
Views: 99,508
Posted By awblain

Why discuss energy and momentum?

Without discussing energy and momentum, I always think that the connection to the physics at work can be lost. Newton's laws deal with momentum conservation and input, Bernouilli's theorem deals with...
Forum: Tech Log
19th Nov 2012, 16:03
Replies: 388
Views: 99,508
Posted By awblain

Down the plughole

Why a whirlpool? - conservation of angular momentum, as speed increases into the drain.

Why a tube of air in the centre into the plughole? Conservation of energy - a dense whirling water core...
Forum: Tech Log
15th Nov 2012, 18:31
Replies: 388
Views: 99,508
Posted By awblain

Lyman, sir. `Newton' and `Bernouilli' are...

Lyman, sir.

`Newton' and `Bernouilli' are both right in their way. `Newton' is couched in terms of conservation of momentum, `Bernouilli' in terms of conservation of energy. Both need to hold. ...
Forum: Tech Log
14th Nov 2012, 22:30
Replies: 388
Views: 99,508
Posted By awblain

Look at the trough in the cloud behind the C17

That's the best picture to see the effect on airflow from the passage of the aircraft: the cloud is lowest along the keel, not in two tracks behind the wingtips.

See the 757 wake smoke too - ten...
Forum: Tech Log
14th Nov 2012, 21:37
Replies: 388
Views: 99,508
Posted By awblain

Newton's vortices?

How does Newton account for vortices?

Air that's flowed over the wings is going down. Air that's closer to the centerline is going down more, air that's further from the centreline is going down...
Forum: Tech Log
1st Nov 2012, 21:15
Replies: 388
Views: 99,508
Posted By awblain

Circulation theory?

I suggest that you could also call `circulation theory' a simple piece of legislation by Mr Newton.

The flowing air lifts up the wing, and the wing pushes down the flowing air.

Behind the...
Forum: Tech Log
25th Jul 2012, 20:41
Replies: 388
Views: 99,508
Posted By awblain

Bernoulli doesn't say anything about where the...

Bernoulli doesn't say anything about where the streamlines go, since it has no description of momentum conservation, although it does a good job of describing what happens along them, since it's...
Forum: Tech Log
24th Jul 2012, 21:10
Replies: 388
Views: 99,508
Posted By awblain

I think Boguing is entirely right. That...

I think Boguing is entirely right.

That picture you posted is wrong - after the air has passed the rotating cylinder its net direction is at a downward angle to the horizontal. There's an upward...
Forum: Tech Log
24th Jul 2012, 20:30
Replies: 388
Views: 99,508
Posted By awblain

The top of the cylinder, moving with the airflow,...

The top of the cylinder, moving with the airflow, speeds up the air at any point compared with a non-rotating cylinder, while the bottom of the cylinder, moving against the airflow, slows the air...
Showing results 1 to 13 of 13


 
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