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Old Jan 21, 2013, 02:37 PM
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I plugged my plane into Thech's thing and it told me that it had a cubic loading of 23 when it was 600 grams? The only way to get it to a beginner level was too have it at about 250 grams?

It also said the stall sped was 25mph?

seems a bit fast
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Old Jan 21, 2013, 02:45 PM
No bounce, No play.
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Originally Posted by jimmy boo View Post
I plugged my plane into Thech's thing and it told me that it had a cubic loading of 23 when it was 600 grams? The only way to get it to a beginner level was too have it at about 250 grams?

It also said the stall sped was 25mph?

seems a bit fast
Yeah, I tried it too. I also put the 50 inch flying boat in that I was telling you about. Comes out to 15 cubic and 22ish stall. I guarantee you that it stalls much slower than that. Stall is dependent on lift coefficient and I don't know if 1.0 is the right number to use.
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Old Jan 21, 2013, 02:54 PM
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^thank you so much, I was getting worried.
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Old Jan 21, 2013, 07:21 PM
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I have deicded to make 3 pieces of foam board on each other, so now there will be a 5 inch chord, two inch onto of that, and a one inch on the top.
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Old Jan 21, 2013, 08:38 PM
Build straight - Fly twisty
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Err, sorry guys. Tip fins do work as dihedral.
Look at this free-flight Nordic A2 sailplane from the 1950s.
I built a similar one (stole the design from this picture) and it flew exceptionally well.
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Old Jan 21, 2013, 08:47 PM
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so, I don't need to bend the wings?
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Old Jan 21, 2013, 09:26 PM
Build straight - Fly twisty
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Err, sorry guys. Tip fins do work as dihedral.
Look at this free-flight Nordic A2 sailplane from the 1950s.
I built a similar one (stole the design from this picture) and it flew exceptionally well.
Free-flight and RC are different beasts.
Those A2 sailplanes had their CG at about 75% and that doesn't work for RC.
Personally I'd go for ailerons. That way you don't have wind gusts working on dihedral to rock and roll the plane, and roll is controlled directly by the ailerons and not as a artifact of 'yaw + dihedral'
Even though I posted that 'blast fron the past' If I had to go for RET I'd use conventional dihedral for your application.
3 to 5 degrees for high wing
5 to 8 for mid wing
More dihedral needs more V-stab area.
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Old Jan 21, 2013, 09:32 PM
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anyways, I made a little prototype and she glided pretty nicely.

I really don't want ailerons, but I am a little confused on what your talking about. <---noob here.

my idea is to have straight wings, but angle them up a bit.

http://www.airplane-pictures.net/ima.../12/156073.jpg

^if you can see, the wings are straight, but angled upwards.

will this keep stable flight.
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Old Jan 21, 2013, 09:54 PM
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I have decided that I am going to transition this to a one motor plane vs two, purely because it will be easier, although idk if someone thinks two is just as easy then i would listen. also, I need recommendations of that motor, a battery, other electronics, a controller etc. <--- lets say under $70. give or take.

It appears like ailerons are a must, but I don't want them. how does the champ do without them.

thanks to all.
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Old Jan 21, 2013, 10:56 PM
Build straight - Fly twisty
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Originally Posted by jimmy boo View Post
my idea is to have straight wings, but angle them up a bit.

http://www.airplane-pictures.net/ima.../12/156073.jpg

^if you can see, the wings are straight, but angled upwards.

will this keep stable flight.
That is an illustration of dihedral.
It will not keep your plane stable in flight. It will act to roll the plane back to level flight after it has been disturbed. There is a difference there.
RET works OK in a limited sort of way. Many many people are happy with it and for your project it will be fine.
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Old Jan 22, 2013, 07:07 AM
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ahh, so like if i were flying around and my plane pitched 20* to the left due to a wind gust, it would kind of slowly bounce back to even.
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Old Jan 22, 2013, 07:21 AM
No bounce, No play.
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ahh, so like if i were flying around and my plane pitched 20* to the left due to a wind gust, it would kind of slowly bounce back to even.
It's not like an immediate/guaranteed thing, but yes, it will have a tendency to want the weight hanging back under the middle again. Also, because the high wing is starting to lose lift compared to the lower one, it will tend to drop the high wing and get back to level.
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Old Jan 22, 2013, 07:37 AM
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You've got 3 pages of great advice here. At this point I would suggest you just draw something up on paper and take a picture of it for us to look at. There are tons of people on here that can tell you not only if it will fly but if it will be easy to fly as well. the amazing thing is you can be off by quite a good bit with motor size and the design of the plane but if you have the center of gravity right and the plane doesn't have tons of drag it will probably fly fine. The C/G can be changed by battery placement when you are almost ready to do the first flight so, get in there, draw it up, show it off.
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Old Jan 22, 2013, 06:07 PM
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^ I kind of did already although ill get a new one up soon if you want.
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Old Jan 22, 2013, 07:57 PM
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overall, the plans are basically the same as before, although now there will be a different looking fuse lodge, i couldn't find anything circle. hehe.
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