Hmmm more of an "I don't care because I am not going to be around then" kind of answer than the truth but I take a few valid points out of your argument such as gliding being frivolous, trivial and useless.
I believe that in 1972 the "Club of Rome" released their report and one of the summary items was that: if the present growth trends in the world population, industrialization, pollution, food production, and resource depletion continue unchanged, the limits to growth on this planet will be reached sometime within the next 100 years. The most probable result will be a rather sudden and uncontrollable decline in both population and industrial capacity. doesn't seem to have much to do with the end of the 20th century to me..... Also I stated: "Considering we are in a resource limited world" which can apply to the past, present and future. Why not do something about this now than put it ahead in the future. Do you think we would have more societal wealth if we have resources for the future or if we have cash in the pocket now??? Todd ________________________________ From: Mike Borgelt <mborg...@borgeltinstruments.com> To: Discussion of issues relating to Soaring in Australia. <aus-soaring@lists.internode.on.net> Sent: Tue, 1 June, 2010 5:20:24 PM Subject: Re: [Aus-soaring] latest jet glider At 11:17 PM 31/05/2010, you wrote: > Considering we are in a resource limited world, 2l sounds a bit better to me > than 5l+ > > Todd > > > From: Ron Sanders <resand...@gmail.com> > To: Discussion of issues relating to Soaring in Australia. > <aus-soaring@lists.internode.on.net> > Sent: Mon, 31 May, 2010 10:02:17 PM > Subject: Re: [Aus-soaring] latest jet glider > > Most IC powered SLGs can get up to 2000' for about 2 litres of fuel. > Most modern ones have a climd of 800 fpm or thereabouts at <50kts with > a steep climb angle. And although there are millions of moving parts > in the engine. they're all the type of part that a chap with a lathe > in the back room can turn up in an hour or so. You can't say that > about the jets, whatever their advantages. > > Far out!!! I ran the numbers for angle of climb. All numbers ISA sea level as per standard practice. For a 400 Kg flying mass modern 15/18m glider with 68 Kg jet thrust static best Angle of Climb is at 50 knots or so at 7 knots climb rate. At 500 Kg, 60 knots at 6.4 knots RoC. In both cases CS22 motorglider takeoff performance is met. You can go to 600Kg like the latest 18m gliders but you need full thrust (80Kg) for the takeoff and it doesn't meet CS22 but still isn't bad. You can throttle back after obstacle clearance and still get a good rate of climb. Just like operating any powered aircraft you take the aircraft weight and conditions of the day into account. No problems here. ----------- Obviously whoever made that comment about engine parts hasn't ever manufactured anything. In principle it is correct. In the real world you need to know the material specification, heat treatment pre and post machining, if any and may need specially treated parts to machine - good luck with getting the raw crankshaft forging, for example or making a crankcase from a billet with a CNC machine. It can be done but is about a difficult as making a set of nozzle guide vanes and a turbine blisk and machining to final shape. That is the only thing that's difficult in the small jets. The compressors are automotive industry parts, the rest alloy steel and aluminium and stainless steel. I think there are more moving parts in the carby of a two stroke than in an entire small turbine engine. ------------ As for a resource limited world - it seems we may already have run out of up and coming engineering talent. When has the world NOT been resource limited in the sense that people want more stuff than they have and it costs more than they are really wanting to pay? Just offhand serious considerations of resource constraint goes back to Thomas Malthus or more recently the Club of Rome around 1970. Their predictions for the end of the 20th Century were way off. I can remember a prediction about how photography was doomed because we were going to run out of silver due to its use in photography. Efforts were made to find a substitute but no satisfactory ones were forthcoming. Look what happened. Sure we can *make* ourselves resource limited by refusing to allow mining or drilling, or refusing to use nuclear power or spending our societal wealth on useless energy sinks like windmills and solar panels but if this goes on .... "eat your Greens" may take on a different meaning. When it gets to whether 2 litres or 5 litres of fuel is required for a glider self launch or 8 litres for an aerotow and it is a serious issue it won't matter. Something as frivolous and trivial and useless as gliding will have been banned, taxed or otherwise driven out of existence and the organisations running it will happily aquiesce as they have done and are doing with all the restrictions placed on the activity up to now. Mike Borgelt Instruments - manufacturers of quality soaring instruments since 1978 phone Int'l + 61 746 355784 fax Int'l + 61 746 358796 cellphone Int'l + 61 428 355784 email: mborg...@borgeltinstruments.com website: www.borgeltinstruments.com _______________________________________________ Aus-soaring mailing list Aus-soaring@lists.internode.on.net To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring
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