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Old May 17, 2013, 10:21 PM
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Would you consider it a good thermal machine? I'm a "flat-lander" so slopes are completely foreign to me.
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Old May 18, 2013, 12:54 PM
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Dave Jones gave me a phone call after I had purchased a lot of his plans. At that time Dave was saying that the "R-2" design was the best of them all for thermaling. At the time I was thermal soaring a slope soaring a lot. Slope soaring you are flying in the wind on a hill top and requires more attention to what you are doing. If you arn't careful the wind can blow your glider over behind the hill. Of course it depends on the wind speed. at about 8 to 10 mph you can get away with flying a thermal glider on the slope. I have flown in the famous Riverside California "Santa Ana" winds with gust up to 60-70 mph. Which is good for hi performance slopers (see attached photos). In my opinion slope soaring is the best bang for the buck!
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Old May 18, 2013, 07:13 PM
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Closest thing to a slope around here is the landfill. It's about 60 feet or so in height. If they ever close it down, I may crawl the fence and try it. Lol.
Looking through the catalog you posted, there were a couple he listed as thermal capable. Maybe with a bit better airfoil.
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Old May 18, 2013, 10:51 PM
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Ravin

sawman

The original Ravin will thermal quite well. It's just than traveling back up wind or through sink is a limitation with this under-cambered airfoil. There is a "Raven II" or something like that which has better performance.

The Scorpio has a flat bottom airfoil with the high point quite far forward on the upper surface. Reflex is all in the trailing edge stock. It, the Scorpio and others, were described in a Model Airplane News soaring article about Dave Jones designs in the 1970's or 1980's.
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Old May 19, 2013, 08:56 AM
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Quote:
Originally Posted by sawman View Post
Closest thing to a slope around here is the landfill. It's about 60 feet or so in height. If they ever close it down, I may crawl the fence and try it. Lol.
Looking through the catalog you posted, there were a couple he listed as thermal capable. Maybe with a bit better airfoil.
Check here for mods on the Raven.....http://www.rcsoaringdigest.com/pdfs/...SD-1999-06.pdf
http://www.b2streamlines.com/MBRaven2.html
http://www.b2streamlines.com/MBRaven3.html
http://www.b2streamlines.com/MBRaven4.html
http://www.geocities.com/aerohydro/mfm/northrop.htm
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Last edited by Vrated; May 19, 2013 at 09:21 AM.
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Old May 19, 2013, 05:22 PM
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Thanks guys. The sunbird is listed as a thermal wing also. I like the lines.
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Old May 29, 2013, 08:27 AM
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Sawman,
Hey, keep us posted on your progress if you build the "Sunbird".
~Fred
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Old May 29, 2013, 08:44 PM
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Building the 3M Sunbird is still on my to-do list.
Its really cool looking, and must be built with the elliptical tips, IMO.
The flat bottom wing profile makes me nervous, to tell you the truth.
I would hate to spend all that time cutting ribs from balsa and end up with a dog flying wing, to be honest.
Mine would definitely have a different wing joining system, wing servos for the elevators, and also a ballast arrangement of some type.

I'll ping you Fred if and when I start one.

R,
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Old May 31, 2013, 11:50 AM
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My thought is may be a "dog" compared to more modern designs, especially with regards to wind penetration, but hardly a bad flier in general. It may be that most folks fly wings on slopes and have come to expect a certain level of performance due to the evolution of designs. My goal is more towards the thermal "gas bags" of yesteryear. No kevlar-wrapped, carbon capped krytonite spars that can withstand 10ex6 million PSI stress.
For my purpose, the flat bottom may work fine. But still I can't help but wonder if there is another profile that may tip the scale?
Target, any ideas of what may be suitable? Maybe EMX-07 or CJ-25²09 ?
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Old May 31, 2013, 03:11 PM
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I would just be guessing to be perfectly honest.
And as such, I will not give a profile.

R,
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Old May 31, 2013, 04:12 PM
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Quote:
Originally Posted by sawman View Post
For my purpose, the flat bottom may work fine. But still I can't help but wonder if there is another profile that may tip the scale?
I had good luck with a thickened PW51 in my Plank 101. Being a light wood framework, It is both a slope ship and a thermal ship. Is it a super floater? No it is not, but with a plank, I think that you will have difficultly finding an airfoil that meets the pitch stability needs of a plank and provides very high lift. You'd need a tail to max out the lift.

There's nothing wrong with a floater that does not penetrate well. You just fly it on calm days and give the turkey vultures a run for their money.

Kent
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Old May 31, 2013, 06:53 PM
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I also was wondering about the PW series; If I was going that way, I would probably just contact Peter Wick himself and ask what he would recommend...

Building a flat bottomed built up wing simplifies the actual construction process, especially with the eliptical tips of the Sunbird.

I think that you are right about the max lift, but I think that the main place one would be at a disadvantage would be "only" on launch and landing, when having a cambered wing helps you. Haha, only.... Still, RES planes do just fine, and a wind design has less fuselage to deal with, so less wing loading.
Bottom line is, if I build one, it snot going to be for ultimate performance, its going to be for ultimate coolness.

R,
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Old May 31, 2013, 10:32 PM
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Thanks. Guess I'll ponder this a while...esp, seeing that my work schedule will keep me from any serious building till next winter.
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Old Jun 04, 2013, 03:56 PM
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Back when I flew thermal gliders regularly I would always practice thermal flying with a 2 meter glider like a "Oly 650" etc. just because it was harder to keep in the air. It helped me to work the lighter thermals quite a bit. I look at flying wings (planks) kind of in the same light. If you can keep one in the air consistently you have honed your thermal flying skills to a higher level. Plus, it just looks cool to see a wing flying high in a thermal. just my 2 C.
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