WIX Archives
You're very welcome n/t
Posted by Richard Allnutt on Fri Oct 05, 2001 04:59:58 PM
In reply top Thanks Christer and Richard ! posted by MickM on Fri Oct 05, 2001 04:34:00 PM
: That's some good and interesting stuff, thanks very much!
:
: Cheers
: Mick
:
:
:
:
: : Mick,
: :
: : again from what I?ve read, the stalling characteristics
: of
: : the Corsair is due to the flap in fully extended landin
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: : position disturb the airflow over the horisontal stabili
: ze
: : r. Especially under cross wind conditions pilots often c
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: : ose to reduce the flap setting. This prompts a higher ap
: pr
: : oach speed with higher margins but, in consequence longe
: r
: : landing distance.
: :
: : I?ve also read a little about the Bearcat, the articulat
: ed
: : landing gear legs were neccesary to fit them into the w
: in
: : g inboard of the cannons.
: : There were several means of achieving this, e.g. the twe
: nt
: : y-series Spitfires, haveing a larger diameter propeller
: th
: : an the earlier Griffon-Spits, had a device which compres
: se
: : d the oleos when retracting the landing gear.
: :
: : Regarding the Stuka, I haven?t got a clue, never studied
: i
: : t.
: :
: : To the subtelties of aerodynamics, well, I?m a keen glid
: er
: : pilot and the design of gliders focus on reducing drag
: be
: : cause it?s simply a drag!
: : One of the most renowned designers is a personal friend
: of
: : mine (have flown his designs for years) and through him
: I
: : ?m acquainted with the work of a professor of aerodynami
: cs
: : at the University of Delft who is into the airfoil rese
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: : ch.
: :
: : I won?t dig too deep into this but generally the drag-co
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: : ficient can be subdivided into three parts:
: : 1) The frontal area of the airframe (what "hits" the air
: fl
: : ow) and the wet area of the airframe (what the airflow h
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: : to travel along). These two together is called the fric
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: : on drag or zero drag (when the airfoil is generating zer
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: : lift).
: : 2) The interference drag is caused by the airflow around
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: : he wing, the horisontal stabilizer and the fin interferi
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: : with the airflow around the fuselage.
: : 3) Induced drag is the drag from all lift producing memb
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: : s. The main contributor is the wing but also the stabili
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: : r and fin generate drag. The higher the lift-coefficient
: ,
: : the higher the drag-coefficient.
: : Lift produced by an airfoil is proportional to the airsp
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: : d and angle of attac. To maintain level flight (at const
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: : t altitude) the angle of attac is high at low speed, usi
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: : a high lift-coefficient. The angle of attac is low at h
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: : h speed using a low lift-coefficient.
: : If you then start turning the angle of attac gets dramat
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: : ally higher, especially at low speeds. This is often ref
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: : red to as bleeding energy.
: : This put together tell you that the induced drag is pred
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: : inant at low speeds and whenever you are turning, and th
: e
: : friction drag is predominant at high speeds.
: : Now we?re back to the Corsair quiz, the interference dra
: g.
: :
: : The friction drag and the induced drag contribute at lea
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: : 90% of total drag and the interference drag contribute
: th
: : e balancing less than 10%, which means that it?s not as
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: : portant as the other two.
: :
: : In glider design today the interference drag is becoming
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: : ore and more important. The other two components of tota
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: : drag have been reduced enough to make a reduction in int
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: : ference drag a significant improvement.
: :
: : Now to another quiz:
: : When a glider flies it trades altitude for speed, unless
: t
: : here are thermals of rising air it will eventually regai
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: : contact with terra firma.
: : The glider weighs some 500 kg, has a rope attached to it
: ,
: : a very long one which runs over a pulley to hang a weigh
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: : at the other end.
: : How much weight is required to compensate for the drag a
: nd
: : make the glider fly without the sacrifice of altitude?
: : (I know the answer for the glider but not for the Corsai
: r!
: : )
: :
: : Regards,
: : Christer