Mike,
I love that math/ geometry, and science, keep it coming.
Larry Bell
On Fri, Jan 2, 2015 at 12:58 AM, Mike via KRnet <krnet at list.krnet.org>
wrote:
> Hi George,
>
> It?s not a ?Brit thing?. In geometry ?normal? is the expression used to
> describe a line which perpendicular to a surface. In the case described in
> the research paper, the flat plate was rigged in the wind tunnel so that it
> was normal to airflow. On a KR fuselage, the bellyboard would only be
> normal
> to the flow if it was deployed at 90 degrees.
>
>
>
> Developing nations have no cause to feel inferior!
>
>
>
> Have a good 2015.
>
> Mike
>
>
>
> _____
>
> From: gluejam [mailto:gluejam at cox.net]
> Sent: 01 January 2015 19:05
> To: Mike; KRnet
> Subject: Re: KR> Bellyboard
>
>
>
> Mike -
>
> Perhaps you can explain why in the report the term, "normal to the airflow"
> rather 'than parallel with', or 'perpendicular to' the airflow is used.
> Is
> that a common reference in the UK? It just seems a little nebulous to me
> in understanding immediately upon reading the report, and it would seem
> sensible to think that normal would be in line with airflow . . .
> but then ours (US) is a lower grade society, after all !!
>
> George
>
> _____
>
>
>
> On 12/31/2014 6:19 AM, Mike via KRnet wrote:
>
> A little science from English researchers in 1957
> http://naca.central.cranfield.ac.uk/reports/arc/cp/0323.pdf but I'm sure
> there must be more recent published findings from elsewhere.
>
> This suggests that a solid airbrake produces a bubble of reduced airflow
> behind the brake with airflow velocity fluctuations occurring around the
> edge of the brake which may cause vibrations to the structure. Perforations
> in the airbrake reduce this effect and were found to be more effective
> towards the centre of the plate than around the periphery.
>
> From the Pprune forum, this explanation was offered: "Perforation reduces
> buffeting downrange of the speed brake, and reduces its interference with
> flying surfaces or the fuselage or wing or horizontal stab. Remember, the
> speed brake is there to create drag, but not undesirable flight
> characteristics. A perforated brake doesn't create nearly the airflow
> disruption, pitch change, or load on the surrounding and supporting
> structure that a solid brake might create. The number and placement of
> holes
> are important considerations, and part of the design. Holes permit a
> lighter
> structure that takes less of an airload, reducing not only the weight of
> the
> brake assembly but the force required to actuate it and the structure
> around
> it that must support the load. Remember that much of the time, that speed
> brake isn't anything but dead weight."
>
> Mike Mold
> Devon, UK.
>
> -----Original Message-----
> From: KRnet [mailto:krnet-bounces at list.krnet.org] On Behalf Of Mac
> McConnell-Wood via KRnet
> Sent: 31 December 2014 10:35
> To: Herbert F?rle; KRnet
> Subject: Re: KR> Bellyboard
>
> The RAF Vulcan bomber had solid airbrakes-no holes (which enabled this 90
> ton delta to descend vertically-..been there..)
> Mac
>
> On Wed, Dec 31, 2014 at 9:51 AM, Herbert F?rle
> <mailto:krnet at list.krnet.org> <krnet at list.krnet.org> wrote:
>
>
>
> ....any Test,however it is performed,gives a lot of informations! The
> aerodynamic principles are always the same ,also in the case of the hot"
> bellyboard -drag" discusion.For me it's important the location of the
>
> board
>
> and I think the place underneath the rearspar is very well chosen ( far
> enough behind the CG ,to give the Kr a small amount of direction stability
> like a dragchute and the waketurbulences does'nt hit the HS !) I 'm
> convinced,a board without holes are more effectiv ( one big
>
> waketurbulence
>
> produce more drag compared to many small ones).
> I'm also think,a big advantage of the bellyboard is the fact ,that you can
> lower the nose of the Kr on final for better sight( wether you have to
>
> push
>
> or pull the stik )!
> Herbert
> German Kr builder .
>
>
> Von meinem iPad gesendet
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