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Old Mar 05, 2012, 12:16 PM
Drifting off the reservation..
JumpySticks's Avatar
USA, LA, Broussard
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I think I'll leave my stabilizer at the factory angle. It seems to fly well there.
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Old Mar 05, 2012, 01:06 PM
Tossing planes into the snow
Canada, BC, Smithers
Joined Nov 2011
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I think I'm going to leave my stabilizer where it is as well, but I do enjoy the discussions on aerodynamic theory. There are forums dedicated to that subject, but I feel that there is a place for it on any forum because each model of plane has it's own variations on the general theme. I have been reading up a bit, trying to understand why planes can fly upside down even though the airfoil should be pulling them towards the ground, and also how planes with no airfoil at all (totally flat wings with squared-off leading edges) can fly so well.

There are experts out there with experience and wind-tunnels and all the tools who are still arguing about these things. Hopefully we can keep the fist-shaking to a minimum here, and offer up our ideas as simply ideas and not as pronouncements from God. There is one member who enjoys dissecting other people's posts line-by-line like a cross-examination lawyer. This is a confrontational approach that stirs up people's anger and turns a friendly discussion into an argument. Nobody has a monopoly on the truth.
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Old Mar 05, 2012, 01:22 PM
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Not to mention his sarcastic remarks.
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Old Mar 05, 2012, 02:26 PM
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Quote:
Originally Posted by WaynejG View Post
Not to mention his sarcastic remarks.
I know who you are talking about and I agree! My Radian Pro flys Great!!!! I think that he does not have a life and lives off the internet.
Gordon
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Old Mar 05, 2012, 02:54 PM
Zor
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Quote:
Originally Posted by flycracker View Post
Geeze, and I have been flying all sorts of sailplanes for some 30 years, having a great time and all this time I haven't known any of this technical information.
It has made for very interesting reading though I think I'll just go on happily flying my planes.
No offense meant. It's good to have those who enjoy a vigorous discourse on the thread.
Have fun and keep at it
Rich
Hi flycracker and all readers,

We, modelers, all have our own interest in the various aspects of our hobby.

kaptondave and myself obviously have interest in "what makes things kick" and we are having a fiendly discussion.

He expresses his viewpoint and I express mine.
I appreciate that kaptondave has similar interests to mine.

I am also hoping that who reads this thread and was not acquainted with the topic can gain some knowledge.

Of course anyone who might be bored with this discussion can refrain from reading his and / or my postings.

I enjoy the discussion and I guess he does also otherwise we would just stop positng.

Zor
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Old Mar 05, 2012, 03:02 PM
Zor
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Quote:
Originally Posted by JumpySticks View Post
I think I'll leave my stabilizer at the factory angle. It seems to fly well there.
Mine does also.
As I wrote earlier, "the designers sure knew what they were doing".

Zor
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Old Mar 05, 2012, 03:17 PM
Zor
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Quote:
Originally Posted by kaptondave View Post
I don't know if anyone cares what AOA results in best L/D because we do not fly by measuring AOA but best L/D AOA is approximately 6 degrees.

For gliders specifically see:

www.memphis-soaring.org/Training/Chap_2.pdf
(Page 3, Angle of Attack)

Also see:

www.nordian.net/pdf/jaa_principles_of_flight_demo.pdf
(Fig PF 4.3.)
kaptondave,

I certainly will not argue the 6 degrees shown in one of the links you provided.

I just read fully both articles the links provide.
5 degrees is also used as well as 6 degrees in the second article.

These articles are quite old referring to the old Bernouilly theorem to explain lift. More recent explanations for lift are based on the mass of air that is deflected downward by the movement of the wings.

I do not know the origin of these articles but judging by the sketces I figure they are aimed for the general readers.

Attached is a graph from a different source that you may find interesting.

Zor
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Old Mar 05, 2012, 04:14 PM
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I have certainly not been enjoying dealing with this person and consider the exchange to be anything but friendly. He takes great pleasure in ripping my posts (and those of others) apart and sprinkling them with insults, and ALWAYS insists on having the last word. The only reason I have been involved is to hopefully correct some of the misinformation being spread. I am sure it is tiresome to some and apologize for that. I should follow my own advice to not feed trolls.
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Old Mar 05, 2012, 05:06 PM
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The discussion of decalage and CG has gone around and around in this thread. As noted in an earlier post, the two angles that determine decalage are not standardized in the technical literature. Kapton Dave gives a precise definition of what he means. He defines decalage as the difference between the chord line of the wing and the chord line of the stab. However, there is nothing fundamental that says that zero decalage is somehow optimum.

What I have found on many sailplanes (Spirit, Radian and others) is that a well trimmed out sailplane (CG and elevator trim adjusted for a shallow glide with little tendency to porpoise) often ends up with the elevator not in line with the stab. This situation adds a miniscule amount of drag compared to a situation where the elevator ends up in line with the stab. I have gone to the same trouble as many have done with their Radians. I have changed the angle of the stab so that the elevator ended up in line with the stab. This seemed somehow satisfying, but I could perceive no difference in flying characteristics.
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Old Mar 05, 2012, 05:35 PM
Tossing planes into the snow
Canada, BC, Smithers
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Quote:
Originally Posted by kaptondave View Post
I have certainly not been enjoying dealing with this person and consider the exchange to be anything but friendly. He takes great pleasure in ripping my posts (and those of others) apart and sprinkling them with insults, and ALWAYS insists on having the last word. The only reason I have been involved is to hopefully correct some of the misinformation being spread. I am sure it is tiresome to some and apologize for that. I should follow my own advice to not feed trolls.
I admire your efforts to keep the record straight. It is often the best strategy to ignore the ignorant. but there comes a time where a person must take a stand. My dad always used to say "The only thing a bully understands is a punch in the nose".
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Old Mar 05, 2012, 05:41 PM
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Just add him to your ignore list in the control panel.. Lifes to long to go thru it with the kind of attitude he has
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Old Mar 05, 2012, 05:46 PM
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Old Mar 05, 2012, 05:46 PM
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Sorry for this but I will not sit back and allow Zor to dismisses my posted references to best L/D AOA by saying:

Quote:
These articles are quite old referring to the old Bernouilly theorem to explain lift. More recent explanations for lift are based on the mass of air that is deflected downward by the movement of the wings.
Facts: The sail plane Flight Training Manual is dated January 1 2008. Principles of Flight is dated 08.05.2008, either May 8 or Aug 5 2008 depending on date format used. Thanks to EZCanuck for pointing that out in a simultaneous post.

Just another example of his style of debate.
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Old Mar 05, 2012, 05:58 PM
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Old Mar 05, 2012, 06:43 PM
Drifting off the reservation..
JumpySticks's Avatar
USA, LA, Broussard
Joined Jan 2011
2,293 Posts
Built a nice T-tail plane once with a flying stab. No issue with decalage there.
Unfortunately, flying stabs are usually fragile and wouldn't be suitable for a "trainer" like the RP.
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