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#11
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Never mind
It is till a good quote (I still think it was Moffat back in the 70s) Robert Bob Johnson wrote: Just to keep stuff straight, while Mr. Moffat has certainly expessed from time to time his fondness for span, I believe "there is no substitute for span" quote comes from Michael Bird ("Platypus") who used to "tinsfos" us quite regularly in S & G (Brit mag) from across the pond ... Of course I could be wrong .. BJ Robert Danewid wrote: There were 2 SZD56 flying in the worlds in Sweden in 1993. They performed nice but not astonishing. One of them even had a minor midair. A year later or so we had one (modified) exhibited at the Annual Swedish Cliding Conference, and as Chris writes, the cockpit were not built for nice looking guys from the West, but supposedly for thin, starving pilots from the eastblock...... (now that has thank God changed!) Moffat once wrote: there is no substitute for span! If you want 50+ go for an 18m or larger ship, if you want nice handling, easy rigging etc, it is easy to trade in som finesse-point to achieve that in a 15m glider! Robert H304 Chris OCallaghan wrote: It's been a few years, but if memory serves Gerhard said that the 27 wing could manage a Finesse (best L/D) of 100, that is, if he didn't have to hang a fuselage off of it. However, most glider pilots like to fly their aircraft in the first person, so he compromised and got a Finesse around 46. The Diana, on the other hand, took the road less travelled by and decided that pilot comfort (or in my case, presence) were not critical marketing factors. Based on that philosophy, I wouldn't doubt that a determined engineer could achieve a Finesse of 50+ for a 15 meter glider. However, we've learned that best L/D is a poor means of judging sailplane performance. It is the flatness of the drag curves on both sides of the intersection that really determine the worth of your glider. A polar free of a low speed bucket and relatively flat increase of sink with speed make a great glider. Might the poles have found a new trick? A more stable high aspect ratio airfoil that needs less tail? A better fuselage/wing transition? Improved laminar control? Perhaps. Paul T wrote in message ... 'DuckHawk 15m racer announced at 2003 SHA Western Workshop. 53:1glide ratio VNE 200 kts' -from Winward Performance - anyone got anymore details? 'SZD-56-2, Diana 2: Newest 15-meter Sailplane.The technologically advanced SZD-56-2 Diana 2 will soar on new wings next summer. Bogumil Beres, chief design engineer of the Diana and owner of Biuro Projektowe 'B' Bogumil Beres, recently announced the design project of a breakthrough Diana 2, featuring a curved wing platform with a continuously varying airfoil and high-performance winglets. The original Diana fuselage will be retained, but with a lower drag fuselage-wing junction. The wing loading range will be 6.08 - 11.7 psf. Most remarkably, the Diana 2 will break the long-standing 15-meter glide ratio barrier of 50/1 with room to spa forecast performance includes a max L/D of 52/1. The prototype Diana 2 wings will fly next August. Diana 2's will be delivered in the Spring of 2005.' Have the Germans got something to worry about? |
#12
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Ian, I thought your "aux vaches" was the M in Nimbus4DM......
Robert Ian Strachan wrote: In article , Bob Johnson writes Just to keep stuff straight, while Mr. Moffat has certainly expessed from time to time his fondness for span, I believe "there is no substitute for span" quote comes from Michael Bird ("Platypus") I do not think that Plat would claim credit for this saying which, regarding straight performance, has been extant in gliding since I started in the 1950s. It refers to the "easiest way to increase performance" (max L/D I suppose), contrasting the relative simplicity of adding span compared to the complexities of adding flaps, new airfoil sections, new configurations, etc. In my own case I remember the Grunau (about 13m I think), good in a thermal but not in a glide, a sort of ancient PW-5. After the Grunau, I progressed through the 15m Meise (well the UK Olympia version anyway) to the Skylark 2 (laminar 15m) to the Skylark 3 & 4 (18m) and finally through various syndicates from 15 to 18m to the Nimbus series, starting at 22m and now 26 in the Nimbus 4DM, twice the span of the dear old Grunau. As far as I am concerned, "there is no substitute for span". In UK soaring conditions, anyway, if you wish to avoid landing "aux vaches". Our vaches may not be very vicious but our roads (for retrieving) are ....... |
#13
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The quote that I've seen attributed to Plat concerning tinsfos is
something to the effect of: "There is a substitute for span, it's called skill, but you can buy span" |
#14
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"There is a substitute for span, it's called skill, but you can buy
span" OK, it's 7:00 PM, the sky has been completely overcast for hours, you have 5000 feet and your looking at a 50 mile final glide. Now SKILL your way home. A very mery Christmas to all my RAS buddies. JJ Sinclair |
#15
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JJ Sinclair wrote:
I own an honest to god, 53:1, 15 meter ship. I'm not kidding, on several occasions the GPS trace shows I am making 100 foot per statute mile. The only problem is, when I measure the wings, the tape reads 86 feet (ASH-25) JJ Sinclair With a back wind of 75 km/h this is no problem for a 15m ship. Noël |
#16
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JJ,
It is clear that, in spite of your vast knowledge of all things connected with sailplane repair, you are using the wrong tool for the job. When I was in the sailmaking business we had a specialized tool which we shop fabricated for just this type of critical work. It's called a jib snap spacing tape and you make it from half inch or inch wide batten pocket elastic marked with indelible markers in suitable increments. In your case I would advise 1 meter marks to make it easy. I bet if you would use the proper tool, as suggested here, and correctly apply it, you'll find your 53:1 glider is pretty close to the desired 15 meter span. Here's wishing you and all of the R.A.S. community health , happiness, and prosperity for the holiday season and the coming year. Cheers!, Pete JJ Sinclair wrote in article ... I own an honest to god, 53:1, 15 meter ship. I'm not kidding, on several occasions the GPS trace shows I am making 100 foot per statute mile. The only problem is, when I measure the wings, the tape reads 86 feet (ASH-25) JJ Sinclair |
#17
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JJ, negative thinking - use the force!
Robert JJ Sinclair wrote: "There is a substitute for span, it's called skill, but you can buy span" OK, it's 7:00 PM, the sky has been completely overcast for hours, you have 5000 feet and your looking at a 50 mile final glide. Now SKILL your way home. A very mery Christmas to all my RAS buddies. JJ Sinclair |
#18
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Here's the figures on the American DuckHawk (got to
be one of the most awful names for a sailplane) from the promo sheet. Windward Performance LLC takes its advanced technology to the racing class. Specifications Empty Weight 300 LBS Gross Weight 900 LBS Wing Span 49.17 FT Wing Area 74.93 FT^2 Aspect Ratio 32.2:1 Length 20.6 FT Horizontal Span 6.8 FT Vertical Height 4.5 FT Structural Limits +11.0 / -9.0 g’s Va, Vb = 165 KTS Vne = 200 KTS Performance At 500 LBS, 6.7 Lbs/FT^2 Best Glide 50:1 at 50 KTS Min Sink 94 FPM at 40 KTS Stall Speed 35 KTS At 900 LBS, 12.0 Lbs/FT^2 Best Glide 52:1 at 67 KTS Min Sink 122 FPM at 57 KTS Stall Speed 47 KTS (data for 900 LBS, 12 PSF) Airfoils Inboard 12.7 % t/c Outboard 10.2 % t/c The DuckHawk has the broadest wing loading range available, the highest maneuvering and redline speeds, and the lowest inertias for snappy handling. The lower flying mass within the 15m span constraint gives an induced drag advantage of 49% at 500 LBS and 33% at 900 LBS (span loading squared) compared to the competition Time will tell - my money is on the Diana 2 which is a development of the SZD-56-1 Diana. (Whose cockpit is bigger than a Ventus a!). Incedently at Leszno they were also talking about an 18m version and 22m Open class version. |
#19
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JJ Sinclair wrote:
"There is a substitute for span, it's called skill, but you can buy span" OK, it's 7:00 PM, the sky has been completely overcast for hours, you have 5000 feet and your looking at a 50 mile final glide. Now SKILL your way home. You don't grasp the concept, JJ: with skill, the pilot is 50 miles out at 6 pm, not 7 pm, and gets home just before all the lift dies. Since I can't buy skill either, I bought a motor. |
#20
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I seem to remember a wonderful letter in Sailplane and Gliding in which
the writer noted that, when he first started gliding in his twenties, average glider LD ratios were around 1:20's. In his thirties, this rose to 1;30's and, at the time of writing, in his forties, 1:40's. He was looking forward to his 100th birthday! May be new materials, better design will prove a substitute for span. The one thing that there will never be a substitute for is Money. Anyone who disagrees may care to explain the absence of K8's from the various handicapped comps. -----Original Message----- From: Glider Pilot Network ] Sent: Wednesday, December 24, 2003 10:10 PM To: Steve Hopkins Subject: [r.a.s] 50+:1 15m sailplanes ------------------------------------------------------------ Newsgroup: rec.aviation.soaring Subject: 50+:1 15m sailplanes Author: Robert Danewid Date/Time: 22:00 24 December 2003 ------------------------------------------------------------ JJ, negative thinking - use the force! Robert JJ Sinclair wrote: "There is a substitute for span, it's called skill, but you can buy span" OK, it's 7:00 PM, the sky has been completely overcast for hours, you have 5000 feet and your looking at a 50 mile final glide. Now SKILL your way home. A very mery Christmas to all my RAS buddies. JJ Sinclair ------------------------------------------------------------ |
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