Shouldn’t vary much at all unless you are up in the plastic temperature region and then all bets are off. :)
Oh, and I am an avionics guy, not a structures guy so I may be way off the mark. Regards, Pete > On 1 Dec 2015, at 5:41 PM, Mike Borgelt <mborg...@borgeltinstruments.com> > wrote: > > I wonder if/how the frequency varies with temperature with glass gliders???? > > > Mike > > > > > > At 04:18 PM 12/1/2015, you wrote: > >> 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 >> >>   Â  135 cycles per minute >> >> Wood  >> >> 3">   180 cycles per minute >> >> Metal  >> >>    192 cycles per 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." >> <aus-soaring@lists.base64.com.au> >> >> To: >> "Discussion of issues relating to Soaring in Australia." >> <aus-soaring@lists.base64.com.au> >> 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 >> _______________________________________________ >> Aus-soaring mailing list >> Aus-soaring@lists.base64.com.au >> http://lists.base64.com.au/listinfo/aus-soaring >> <http://lists.base64.com.au/listinfo/aus-soaring> >> >> _______________________________________________ >> Aus-soaring mailing list >> Aus-soaring@lists.base64.com.au >> http://lists.base64.com.au/listinfo/aus-soaring >> <http://lists.base64.com.au/listinfo/aus-soaring>Borgelt Instruments - >> design & manufacture of quality soaring instrumentation since 1978 > www.borgeltinstruments.com > <http://www.borgeltinstruments.com/>tel: 07 4635 5784 overseas: > int+61-7-4635 5784 > mob: 042835 5784 : int+61-42835 5784 > P O Box 4607, Toowoomba East, QLD 4350, Australia > > _______________________________________________ > Aus-soaring mailing list > Aus-soaring@lists.base64.com.au > http://lists.base64.com.au/listinfo/aus-soaring
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