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Search: Posts Made By: Owain Glyndwr
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Forum: Tech Log
29th May 2012, 12:09
Replies: 95
Views: 32,257
Posted By Owain Glyndwr

Microburst, Guess I'm taking things too...

Microburst,

Guess I'm taking things too seriously ;)
Forum: Tech Log
28th May 2012, 05:51
Replies: 95
Views: 32,257
Posted By Owain Glyndwr

Microburst, If "you guys" are PJ2 and...

Microburst,

If "you guys" are PJ2 and myself, I was referring to the alternative source of material similar to that contained in Shevell's book (which you were interested in obtaining) and which...
Forum: Tech Log
26th May 2012, 16:08
Replies: 95
Views: 32,257
Posted By Owain Glyndwr

Microburst, PJ2 seems to have found the .pdf...

Microburst,

PJ2 seems to have found the .pdf source I recommended to you via a PM ;)

It is very good.
Forum: Tech Log
20th May 2012, 12:58
Replies: 95
Views: 32,257
Posted By Owain Glyndwr

Microburst, As you probably guessed I am...

Microburst,

As you probably guessed I am (was) an engineer, so perhaps not the best person to judge whether Shevell's book is apt for non-engineers. Dick (I met him once) was Chief Aerodynamicist...
Forum: Tech Log
20th May 2012, 11:12
Replies: 95
Views: 32,257
Posted By Owain Glyndwr

Yeah, aircraft designed for high manoeuvrability...

Yeah, aircraft designed for high manoeuvrability might be designed to be unstable and rely on artificial stability.

Don't start me off on canards - they have their disadvantages :D
Forum: Tech Log
20th May 2012, 11:01
Replies: 95
Views: 32,257
Posted By Owain Glyndwr

Correct :ok:

Correct :ok:
Forum: Tech Log
20th May 2012, 10:59
Replies: 95
Views: 32,257
Posted By Owain Glyndwr

rrr That's because you are going one way...

rrr

That's because you are going one way down the control path, I'm going the other!

Let me quote again from my "Bible" - Dick Shevell's book (p.315 in Iss 2)

"Stick fixed stability means...
Forum: Tech Log
20th May 2012, 07:08
Replies: 95
Views: 32,257
Posted By Owain Glyndwr

Yeah, it is difficult to see exactly what is...

Yeah, it is difficult to see exactly what is meant by stick fixed/free stability these days - but then stick free stability hasn't meant much since aircraft have been fitted with hydraulically driven...
Forum: Tech Log
19th May 2012, 14:01
Replies: 95
Views: 32,257
Posted By Owain Glyndwr

Agreed Except that it doesn't work like...

Agreed

Except that it doesn't work like that. Force is equal to the rate of change of (vertical) momentum; that is it equals the mass flow over the wing times the vertical velocity imparted to...
Forum: Tech Log
19th May 2012, 12:14
Replies: 95
Views: 32,257
Posted By Owain Glyndwr

XPM Hmm - different definition of...

XPM



Hmm - different definition of 'downwash' is causing a problem. In this FAA document they seem to be using downwash to describe a force where I am using it to describe an angle of flow.
...
Forum: Tech Log
19th May 2012, 11:50
Replies: 95
Views: 32,257
Posted By Owain Glyndwr

Sure, tail fuel is used to reduce trimmed drag,...

Sure, tail fuel is used to reduce trimmed drag, but do you really understand how it does so?
Negative lift (pitch up trim) means that to balance the overall lift/weight equation the wing must...
Forum: Tech Log
19th May 2012, 10:04
Replies: 95
Views: 32,257
Posted By Owain Glyndwr

Not exactly true - the higher the airspeed the...

Not exactly true - the higher the airspeed the lower the wing AoA and the lower the downwash angle at the tail (which is usually about 40% of the wing AoA)
Plus of course the fact that downwash...
Forum: Tech Log
19th May 2012, 06:57
Replies: 95
Views: 32,257
Posted By Owain Glyndwr

Hmmm ... but on a certain very fast tailless...

Hmmm ... but on a certain very fast tailless aircraft the wing/body cp and cruise CG (with fuel transfer) were arranged so that the elevons were deflected slightly TE down (positive lift) to keep the...
Forum: Tech Log
18th May 2012, 12:12
Replies: 95
Views: 32,257
Posted By Owain Glyndwr

Microburst Know the feeling:ok: ...

Microburst



Know the feeling:ok:



Vertical axis is pressure difference relative to ambient pressure divided by freestream dynamic pressure - negative values are suctions, positive values...
Forum: Tech Log
16th May 2012, 14:31
Replies: 95
Views: 32,257
Posted By Owain Glyndwr

Turin Most people find mathematics a very...

Turin
Most people find mathematics a very useful common language in these circumstances. It introduces a discipline that avoids the sort of confusion your approach leads to.:=

Microburst

Not...
Forum: Tech Log
14th May 2012, 06:57
Replies: 95
Views: 32,257
Posted By Owain Glyndwr

If I may chip in .... At zero lift a...

If I may chip in ....

At zero lift a normally cambered airfoil will have a negative (nose down) pitching moment which is a couple. This means that the cp at zero lift is out at infinity somewhere...
Showing results 1 to 16 of 16


 
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