Of course there is nothing preventing the people
involved from commenting here, as Justin Couch is already doing.
Also GFA and its officials aren't the fount of
all knowledge relating to gliding.
Why would anyone want to comment on a heavily
censored website? You can bet nothing critical of
GFA policy will ever get published, just like has happened in the magazine.
Reminds me of the old Cold War joke:
Scene: Monthly meeting of the Worker's Soviet at
the People's Tractor factory No.27.
After discussing various tractor production
issues the chairman gives his half hour speech in
praise of Marxism-Leninism, the Dialectic,
exhorts the workers to even greater efforts in
the future and then asks "any questions". Guy up
the back puts his hand up and asks:
"What happened to the guy who asked the question at last month's meeting?".
Fortunately the GFA can't send you to the Gulag,
as much as they'd like to prevent inconvenient questions being asked.
Yet.
Mike
At 09:09 PM 12/1/2015, you wrote:
What, and be belittled again. No thank you Sean.
Chris McDonnell
AO Gympie GC
From: <mailto:[email protected]>Sean Jorgensen-Day
Sent: Tuesday, December 01, 2015 8:11 PM
To:
<mailto:[email protected]>'Discussion
of issues relating to Soaring in Australia.'
Cc: <mailto:[email protected]>[email protected]
Subject: Re: [Aus-soaring] Wing frequency Procedure
I think this would be worth moving to the GFA
Forum, where you have a chance of alerting those
who can make changes to the training regime and the BSE.
From: Aus-soaring
[mailto:[email protected]]
On Behalf Of Christopher McDonnell
Sent: Tuesday, 1 December 2015 5:02 PM
To: [email protected]; Discussion of
issues relating to Soaring in Australia. <[email protected]>
Subject: Re: [Aus-soaring] Wing frequency Procedure
Thanks Stephen. Thorough as usual are you.
Smile
Chris
From: <mailto:[email protected]>[email protected]
Sent: Tuesday, December 01, 2015 4:18 PM
To:
<mailto:[email protected]>Discussion
of issues relating to Soaring in Australia.
Subject: Re: [Aus-soaring] Wing frequency Procedure
From the old MOSP 50. Section 3 on Form 2s
============================================
3-2-2
(3) Wing Frequency Check
All new sailplanes delivered now have stated in
their airworthiness documentation the natural
vibrational frequency of at least the wings.
We all know that a drinking glass will
âringâ when tapped, but if it is cracked it
will be âdeadâ. Similarly our sailplane
structure will respond to internal damage, loos
wing root fittings etc by changing the frequency at which it wants to vibrate.
Clearly it will be important to KNOW the
frequency of the structure when new and keep
track of any natural lowering of this value with
age such that a sudden change can be detected and become meaningful.
WHEN:
At each Form 2 and after any air load or ground
load incident particularly heavy landings and ground loops.
HOW:
With the sailplane sitting on its undercarriage,
tyres at correct pressure, on a paved surface,
empty, wings level, gently grasp one wing tip
and shake it up and down. The wing will flex at
a steady rate. It will find its own frequency
and it is next to impossible for you to change
it. Using a suitable watch, time the natural
frequency, a complete cycle being UP and DOWN.
This value should then be compared to what was
found last time or what is specified for that sailplane.
As a guide only, some typical values:-
F.R.P
135 cycles per er minute
Wood
180 cycles per er minute
Metal
192 cycles per er minute
Remember - excessive heaving and shoving at the
wing tip can be quite damaging.
============================================
Regards
SWK
----- Original Message -----
From:
"Discussion of issues relating to Soaring in
Australia."
<<mailto:[email protected]>[email protected]>
To:
"Discussion of issues relating to Soaring in
Australia."
<<mailto:[email protected]>[email protected]>
Cc:
Sent:
Tue, 1 Dec 2015 15:15:48 +1100
Subject:
Re: [Aus-soaring] Wing frequency Procedure
>>a document on how the GFA would like it performed
Doesn't this vary from manufacturer to manufacturer? Some allow wing
frequency checks while on the wheel while others require the fuselage
to be in a cradle or similar. My guess is that the GFA would say
'follow the manufacturer's recommendations'.
Here's one they prepared earlier:
Wing oscillation frequency:
approx. 160/min 15 m span with winglets
approx. 130/min: 18 m span without parting
approx. 124/min: 18 m span with parting and winglets
Aircraft should rest on both wheels during frequency measurements.
I think the last part is critical for each manufacturer.
D
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www.borgeltinstruments.com
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