With respect to ballast bags, can anyone tell me why so many older gliders (without ballast bags) can no longer carry water? What is the problem?
On Mon, Aug 28, 2017 at 10:38 PM, Noel Roediger <roedi...@internode.on.net> wrote: > The best ballast bags I ever used were made by Clipper Plastics – a > Melbourne based company. > > > > They had patterns for all sailplanes requiring such and the bags were > reasonably priced. > > > > Noel. > > > > *From:* Bruce Taylor [mailto:brucetaylo...@bigpond.com] > *Sent:* Monday, August 28, 2017 3:32 PM > *To:* 'Justin Sinclair'; 'Gary Stevenson' > *Cc:* 'Discussion of issues relating to Soaring in Australia.'; 'Anthony > Smith'; 'Gliding Australia Forum' > *Subject:* RE: [gfaforum] RE: water bags and tanks > > > > Hi Gary and all, > > > > In regard to sourcing ballast bags, there is a company at Currumbin in Qld > called Turtle Pac who make all kinds of water and fuel bags for aviation > and marine use. You will find them at http://www.turtlepac.com/ > > > > I have used them in the past, as have a number of other gliding people, > and they appear to provide a good quality product and are very pleasant and > easy to deal with. > > > > Speaking of “Super ships” and matters of weight and balance, it is my > experience that as weights and wing-loadings inevitably increase, then the > chance of getting the loading wrong enough to matter also increases. The > JS1 is a beautiful glider to own and fly, but it is the first glider that I > have been involved with that has a real potential to be loaded well outside > of its C of G limitations. Particularly in 21m span, the large wing ballast > load, two separate tail tanks, jet fuel load and of course various pilot > weights require that you do actually sit down with the supplied loading > spreadsheet and put all the correct numbers into the calculation. > Wing-loadings close to 60kg/sq m are a real hoot to fly with, but need to > be treated with much respect. > > > > On the upside, the EASA-specified certification flight testing is now > incredibly rigorous, so you can be assured that if you do get the numbers > wrong, or have a ballast-dump malfunction, the glider will be doing its > best to keep you alive. Things have changed since gliders like the Cirrus > were certified! Spinning the JS1C/21m with a fully asymmetric ballast load, > with the C of G WAY behind the aft limit, makes for particularly exciting > viewing! It’s on Youtube somewhere. > > > > Cheers, BT. > > > > *From:* Justin Sinclair [mailto:justinjsincl...@hotmail.com > <justinjsincl...@hotmail.com>] > *Sent:* Monday, August 28, 2017 7:38 AM > *To:* Gary Stevenson > *Cc:* Discussion of issues relating to Soaring in Australia.; Anthony > Smith; Gliding Australia Forum > *Subject:* Re: [gfaforum] RE: water bags and tanks > > > > My only comment having been involved as CFI of a club that has had an > asymmetric balance accident would be that *"if"* you can pick that you > have asymmetry make sure do a fast landing. > > > > I am not sure of the speed or flap setting but logic would dictate > something above your normal fully ballasted/slow thermalling speed. The > idea would be to lower the wing onto the ground before you lose aileron > effectiveness, but do not do the traditional stall it on landing otherwise > you get a big surprise as the heavy wing drops first. > > > > The issue with asymmetry should be structural not aerodynamic. Even if one > wing has 200lts of water in it you average wing can easily develop enough > angle of attack to pull 3G or 600lts/kg, so as long as you have speed/AoA > you will be fine. > > > > My only other advice would be if you use tape to cover the vent holes > instead of wing sticks make sure you do a proper ABCD walk around just > before you jump in the seat and use any colour tape other than white. > > > > Justin > > > > Justin Sinclair > > 17 Queen St > > Scarborough Qld > > > > 0421061811 > > > On 28 Aug 2017, at 12:18 am, Gary Stevenson <gstev...@bigpond.com> wrote: > > Hi Noel, > > Tend to agree with you here. > > > > Re “twisted” I am sure that this does not apply only to the bags. Think > about some of the pilots you know! > > > > You say *“Generally a sailplane will not display an imbalance until > stalled. One wing doesn’t know it’s heavier than its partner until then.”* > A very interesting point, which I have had the misfortune to inadvertently > explore a little bit, but – thank God – never seriously in the air. > > > > Without doubt the use of water ballast introduced a whole new dimension > to gliding, as, just co-incidentally Mike B mentioned in a concurrent post. > However it use is something that should never be treated *lightly* > [groan]. A couple of hundred litres of ballast will turn your pussy cat > into a tiger: In the glide; into a missile ..... almost. Take care that > you are not lined up on one of your mates. > > > > You say “*A number of prototype sailplanes have been lost while testing > their ability to remain controllable at the stall with max. Imbalance” * I > have never had the chance to own/fly a current “super-ship”, but from the > literature , they have (as a minimum), inboard tanks, outboard tanks, and > fuselage tanks. It would seem to me that the situation could become > somewhat fraught, if the slightest thing goes wrong with the dumping > arrangement. > > > > Would any knowable person like to make comment here? > > > > Finally we come to the important practical question of “good ballast > bags”. It would seem that these are becoming hard to source, due to > potential liability issues. Who in Australia, or elsewhere, are making new > replacement bags? > > > > Regards, > > Gary > > > > > > > > > > > > > > > > > > > > > > *From:* Aus-soaring [mailto:aus-soaring-boun...@lists.base64.com.au > <aus-soaring-boun...@lists.base64.com.au>] *On Behalf Of *Noel Roediger > *Sent:* Sunday, 27 August 2017 10:18 PM > *To:* 'Anthony Smith'; 'Discussion of issues relating to Soaring in > Australia.'; 'Gliding Australia Forum' > *Subject:* Re: [Aus-soaring] [gfaforum] RE: American Soaring Symposia > > > > Thanks Anthony. > > > > The final question asked of Wil re assymetric water ballast merits further > comment particularly for those who fly sailplanes with bags instead of > tanks. > > > > I believe good ballast bags far outweigh the problems exhibited by rigid > tanks which often leak into the surrounding structure. > > > > Having said that I don’t know of any “bagged” tank that is not extended > and held in place by a rear cord. > > > > In reality bags should be held by two cords. One at its rear as is the > norm but also one at its front to eliminate the possibility of its leading > edge falling over the aft edge and becoming twisted. > > > > > > > > Regards > > > > Noel. > > > > *From:* Anthony Smith [mailto:anthony.sm...@adelaide.on.net > <anthony.sm...@adelaide.on.net>] > *Sent:* Sunday, August 27, 2017 6:32 PM > *To:* 'Discussion of issues relating to Soaring in Australia.'; 'Gliding > Australia Forum' > *Subject:* [gfaforum] RE: [Aus-soaring] American Soaring Symposia > > > > Part of the Wil Schumann paper is here: > > > > http://www.betsybyars.com/guy/soaring_symposia/72-modif.html > > > > *From:* Aus-soaring [mailto:aus-soaring-boun...@lists.base64.com.au > <aus-soaring-boun...@lists.base64.com.au>] *On Behalf Of *Ron Sanders > *Sent:* Sunday, 27 August 2017 6:22 PM > *To:* Gliding Australia Forum <gfafo...@glidingaustralia.org>; Discussion > of issues relating to Soaring in Australia. <aus-soar...@lists.base64.com. > au> > *Subject:* [Aus-soaring] American Soaring Symposia > > > > Any body got any idea where is can get any of these publications from the > seventies?? > > Wil Schumann did a clean up of a libelle that i would like to read about > again. > > > > Ron > > -- > You received this message because you are subscribed to the Google Groups > "Gliding Australia Forum" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to gfaforum+unsubscr...@glidingaustralia.org. > To post to this group, send email to gfafo...@glidingaustralia.org. > Visit this group at https://groups.google.com/a/ > glidingaustralia.org/group/gfaforum/. > > > > [image: Image removed by sender.] > <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient> > > Virus-free. www.avg.com > <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient> > > > > -- > You received this message because you are subscribed to the Google Groups > "Gliding Australia Forum" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to gfaforum+unsubscr...@glidingaustralia.org. > To post to this group, send email to gfafo...@glidingaustralia.org. > Visit this group at https://groups.google.com/a/ > glidingaustralia.org/group/gfaforum/. > > -- > You received this message because you are subscribed to the Google Groups > "Gliding Australia Forum" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to gfaforum+unsubscr...@glidingaustralia.org. > To post to this group, send email to gfafo...@glidingaustralia.org. > Visit this group at https://groups.google.com/a/ > glidingaustralia.org/group/gfaforum/. > > -- > You received this message because you are subscribed to the Google Groups > "Gliding Australia Forum" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to gfaforum+unsubscr...@glidingaustralia.org. > To post to this group, send email to gfafo...@glidingaustralia.org. > Visit this group at https://groups.google.com/a/ > glidingaustralia.org/group/gfaforum/. > > _______________________________________________ > Aus-soaring mailing list > Aus-soaring@lists.base64.com.au > http://lists.base64.com.au/listinfo/aus-soaring > >
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