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Sunshine Coast, Australia
Joined Sep 2004
1,116 Posts
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I had a 3m glider with S3120 back in the day. That section is an update on E207. In other words it is 'flat-bottomed' but despite that it is reasonably efficient at moderate wing loading and for moderate speeds. In other words I doubt this plane will be a warmliner but it should be very nice for chasing thermals and moving around the sky from one thermal to the next.
I'm not sure if the speed range will be enough to make an enjoyable electro-sloper. Time will tell ![]() Ken. |
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Joined Dec 2009
67 Posts
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This sailplane has a LOT going for it, even with many outstanding competitors from eastern Europe. Firstly, those instructions are among the best I've seen: clear, detailed and without leaving guesswork. E-Flight has done its homework.
Secondly, many of us have the recommended components, or at the very least, are very familiar with those listed. I've always had a fear of 2.4 and carbon fiber, even if the later is not that close to the receiver; the manual eases that concern by showing me where my 7010 will go, and there's lots of room so that the ESC, receiver and battery are not crammed together. With Horizon's marketing, no doubt there will be so many sold that we'll have full radio programming guides/threads for all radios and tuning suggestions for camber, reflex and CG...it's a nice transition from a Radian Pro or even a good RES. Thirdly, the 2.9 meter size is a real sweet spot: much larger than a 2M with the price of a 2M composite. Warmliner, mild areobatics, 'sport' slope, winch and ALES give the plane a very wide target audience. And those of us raised on a diet of Aqulias, Bird of Times and Sagittas will appreciate a return to the familiar 3M size. To me it is the perfect "slemerling" size. I'm hard-pressed to think of sailplane with that wide of use envelope that won't have my hobby shop saying "what is that" or "we don't order from Europe". Fourthly, parts/support: yes, many European kits are 1st rate quality; but waiting for a wing, or stab, or other part from Czechoslovakia has spawned many an unpleasant thread here. No doubt Horizon will order sufficient quantity and parts will be available quickly and on this continent. Price: it's not $249 and it's not $999, but rather in the $700ish range, ready to fly. Is it worth 3 -1/2 x a Radian or 2x a Cularis? ...yes it is, and they are in different leagues anyway. And then there's the build: even if you have balked at anything that's not BNF, it's hard to go wrong with that manual ...giving those who would like to improve their building skills a great place to start without fear of hacking up a kit or doing something wrong. Even with 35 years experience, I learned a trick or two reading through the manual. Of course, all the above becomes moot if it doesn't handle and thermal as the videos suggest. But with reasonable wing loading, full flying stab and well-thought out design it's at least a very good sport plane, and probably a great tool for thermal duration or ALES contest work. One suggestion for Horizon to think on: How about a (reasonably priced) wing bag and carrying case?...you could probably sell enough of them to get it well under $100; we want these wings protected when travelling and it's a big, nicely finished plane that will surely search out any hanger rash it can find. |
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I would be very interested to hear the back story on this design. E-flite is owned by Horizon Hobby, an International operation, & several HH employees have posted in this thread. If it's not commercially sensitive, perhaps one of them could advise whether the design comes out of the USA or is an International collaboration? (The slope soaring in the marketing video appears to be over UK terrain) Interested whether someone on the design team flew in the 70's or has flown 70's sailplanes, as there is that feel there in some of the features. The choice of airfoil - why the SD3021 ilo the MH30, or something from the Drela or Quabek stables?? Bringing a product to market from original concept to manufacturing process & marketing is an interesting journey & along the way decisions are taken & choices are made. Can some of it be told?? & finally, I am curious why this thread got kicked off out of Australia? G2 |
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LI, New York, USA
Joined Mar 2003
22,120 Posts
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Note that there is no SD3021 airfoil. the proper designation s S3021 which was very popular in the mid 90s.
The airfoil was designed by Michael S. Selig http://www.rcgroups.com/forums/showthread.php?t=458260 http://www.ae.illinois.edu/m-selig/u...aAirfoils.html |
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I believe he was a research assistant for Michael Selig in the 1980's - "Also available here online and in printed format by SoarTech Aero Publications is the book Airfoils at Low Speeds (aka SoarTech 8), which includes wind tunnel data on 54 airfoils tested at Reynolds numbers ranging from 60,000 to 300,000. The book contains extensive commentary and analysis. Testing was performed at Princeton University during 1987 and 1988 by Michael Selig, John Donovan and David Fraser. This work was the important precursor to the low Reynolds number airfoil research at UIUC." http://www.ae.illinois.edu/m-selig/uiuc_lsat.html Whether the S3021 & the SD3021 are one & the same airfoil with 2 designations, I am not sure at this stage. More digging to do. G2 |
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LI, New York, USA
Joined Mar 2003
22,120 Posts
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It seems unlikely that Selig would produce two airfoils with the same numerical designations, one S3021 and one SD3021.
If you read the paper at the link, authored by Selig, you see that he refers to it as S3021. Since he designed it, I think I will go with his designation. Not all of his designs were done with Donovan. Again, if you look at the paper, authored by Selig it is co-authored, not by Donovan, but Ashok Gopalarathnam. Copyright 1997 by Michael S. Selig and Ashok Gopalarathnam Thus you the S3021 - Designed by Selig SD7037 - co designed with Donovan SA7035 - co designed with Ashok. How did I know this? I didn't. I went to learn about this SD3021 airfoil cited in the specs for this glider and found out there is no such aifoil. It is a mistake, unless Horizon went back to Selig/Donovan and had them design a new aifroil for this glider. |
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It appears somewhere way back the 'D' got slipped in & has been used by other kits & designers since then. It was covered in 2005 per: http://www.rcgroups.com/forums/showthread.php?t=458260 G2 |
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I wondered if you knew someone in E-Flite or had been involved in its development. G2 |
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Joined Apr 2012
1,444 Posts
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Many, many, years ago I read an article about propitiatory airfoils. Sometimes a company would acquire exclusive rights and block anyone else from using the designation because it was included on copyrighted plans. So? It became common for a kit manufacturer to make a tiny little mod or just imply a mod and then change the designation by one letter or numeral. This would avoid legal entanglements while still using a similar designation to take advantage of the familiarity and popularity of a given airfoil. I have no idea if this even still goes on, much less that this happened with this glider, but it would explain a somewhat ambiguous designation.
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This is an awesome glider, nothing with this size and performance else even comes close for this price range. I just put my order in with Horizon. Any estimates when it will be shipping ??? Mike |
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