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Old Sep 13, 2012, 11:02 PM
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Also the problem with visualizing speed is it is ground speed you are seeing and not air speed. They can be very different and this is a big reason the down wind turn myth gains followers.
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Old Sep 14, 2012, 05:06 AM
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Originally Posted by cfircav8r View Post
Also the problem with visualizing speed is it is ground speed you are seeing and not air speed. They can be very different and this is a big reason the down wind turn myth gains followers.
This was clear on day when a heli pilot nearly lost it doing a roll in front of himself. Dispite traveling left to right at a jogging pace the roll went pear shaped in a big way (but he saved it) and we all had a good laugh when we realised the smoke trail was traveling left to right faster. He actually had negative airspeed when he entered the roll....
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Old Sep 14, 2012, 09:07 AM
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A very good example of the dangers of using ground speed to judge air speed. Too bad more people can't see these kinds of examples more often.
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Old Sep 14, 2012, 08:08 PM
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Originally Posted by cfircav8r View Post
Also the problem with visualizing speed is it is ground speed you are seeing and not air speed. They can be very different and this is a big reason the down wind turn myth gains followers.
I see that you are relatively new to the forum. Please take this as a constructive suggestion, not criticism.

What you say is true but it is a fundamental premise of this topic and has been extensively discussed in earlier posts. When joining a discussion it is good practice to read what has gone before.
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Old Sep 14, 2012, 10:58 PM
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When joining a discussion it is good practice to read what has gone before.
Actually this advice should be directed at the trolls who love bringing up the downwind turn bunk and should read " When joining a forum it is good practice to read what threads have gone before."

But after you've been on here long enough, you realise that downwind turn threads are created by those who have little to do in their life and are responded to by those who either don't know any better or just like a good laugh. I like a good laugh
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Old Sep 14, 2012, 11:41 PM
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I merely responded to a current post with an appropriate point. Simply stating that it was covered already is not very productive. Very few will take the time to read through 15 pages of posts and try to determine which post is relevant to their statement. Also this is a discussion thread and points are often repeated and reworded to help with understanding and to keep the idea fresh. Two of the principles of learning are recency and intensity, so the more we reiterate these principles the better people will learn and remember them. That should be our goal after all. If you believe we should just respond with "asked and answered" or "that was covered already" we might as well close the threads, as just about everything has been covered by now with the exception of new products. I understand your point, I just don't agree with it. I have read the entire thread and if you reread it you will find many points repeated and reworded in an attempt to drive an idea or point home. Not everyone gets it the first time and not everyone gets the original wording.
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Old Sep 15, 2012, 07:00 AM
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Originally Posted by bjr_93tz View Post
But after you've been on here long enough, you realise that downwind turn threads are created by those who have little to do in their life and are responded to by those who either don't know any better or just like a good laugh. I like a good laugh
If you are just here for a good laugh, then that makes you the troll, in the most classic sense of the word. If you go back and read post #1 you will see that the purpose of this thread is to have a friendly discussion without trolling, or accusing people of not having a life, or as the kapton likes to do...accusing people of being off-topic.

If this is where you have to go for laughs, then maybe you need a life also. Please try to keep this discussion civilized.
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Old Sep 15, 2012, 09:14 AM
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Originally Posted by cfircav8r View Post
I merely responded to a current post with an appropriate point. Simply stating that it was covered already is not very productive. Very few will take the time to read through 15 pages of posts and try to determine which post is relevant to their statement. ....
Good points cfircavr, but when you have been following a long discussion since the beginning you might become weary of seeing answers repeated multiple times. It is like being in a class when a new student joins midterm and starts asking questions or stating points that were covered in the first week. In this case your point was made on the first page so it would not be necessary to read the entire thread to get it.

That said, I will try to be more patient in the future.
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Old Sep 15, 2012, 09:39 AM
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If you are just here for a good laugh, then that makes you the troll, in the most classic sense of the word. If you go back and read post #1 you will see that the purpose of this thread is to have a friendly discussion without trolling, or accusing people of not having a life, or as the kapton likes to do...accusing people of being off-topic.

If this is where you have to go for laughs, then maybe you need a life also. Please try to keep this discussion civilized.
Agreed Jovanx, and thanks for being a fan. Just to set the record straight I do not like flagging off-topic posts but might do so when appropriate. That has happened only once in recent memory.
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Old Sep 15, 2012, 07:17 PM
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@ kaptondave & Jovanx,

If you've read any of my post on this thread apart from the last, then you'll realise just how rediculous your comments are.

And Kaptondave, you started that particular reply when you took a "you're new an should read the whole thread before commenting" stance with cfircav8r.

Now, by "have a good laugh" I meant exactly that. Observe the comments, have a good laugh and try to put in something relevent and constructive to correct the misunderstanding. Like my friend with his chopper I didn't "troll" him into nearly losing it but we were still able to have a good laugh about it.

+1 to the pair of you for finally posting something on RCgroups that I've taken personally.
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Old Sep 15, 2012, 07:48 PM
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bjr_93tz, you have characterized the downwind turn topic as "bunk". Exactly what is it that is bunk? Aside from you everyone seems to take it seriously and be interested in learning the truth. I have seen nothing to "have a good laugh" about.
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Old Sep 16, 2012, 09:23 AM
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Originally Posted by cfircav8r View Post
I merely responded to a current post with an appropriate point. Simply stating that it was covered already is not very productive. Very few will take the time to read through 15 pages of posts and try to determine which post is relevant to their statement.
That is an interesting point that applies to all threads on all forums. Should someone with a question or an answer be excused from even trying to see if it has already been answered? Should every question and answer, no matter how many times it has been posted, be treated as it were the first time? If so then why even bother to maintain archived data bases and search functions that require a large investment in computer resources? Just keep the most recent 30 days of posts and throw the rest out.

Just food for thought.
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Old Sep 16, 2012, 09:37 AM
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If a model was being dived vertically down and was allowing for the wind drift would there be any difference in the models airspeed as it was pulled up sharply through 90 degrees into the wind or downwind?
The model would obviously need to be pointed into the wind slightly as it was diving to keep a vertical track relative to a fixed point on the ground. This is what aerobatic flyers have to do all the time.
So pulling up into wind it might only have to turn through say 85 degrees and downwind it would need 95 degrees. (approx)
What would happen in a 20mph wind? During the pull out the model would have roughly the same ground speed in either direction.
Hope that makes sense?
Jim
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Old Sep 16, 2012, 10:01 AM
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Kapton how would you respond? While the exact scenario and question have not been asked yet the answer has been given. I have a flight line of F-16's waiting for some TLC and have to get going so I will catch up in about 14 hours to see how you handle his post.
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Old Sep 16, 2012, 05:08 PM
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Originally Posted by Fox-composites View Post
If a model was being dived vertically down and was allowing for the wind drift would there be any difference in the models airspeed as it was pulled up sharply through 90 degrees into the wind or downwind?
The model would obviously need to be pointed into the wind slightly as it was diving to keep a vertical track relative to a fixed point on the ground. This is what aerobatic flyers have to do all the time.
So pulling up into wind it might only have to turn through say 85 degrees and downwind it would need 95 degrees. (approx)
What would happen in a 20mph wind? During the pull out the model would have roughly the same ground speed in either direction.
Hope that makes sense?
Jim
Ignoring the practical problems associated with sharply pulling out of a vertical dive without the turn itself affecting the airspeed - if the model had been diving vertically in a 20 mph wind the ground position would be moving downwind at 20. After the turn in the upwind direction the ground speed would be reduced by 20. After the downwind turn it would be increased by 20. The airspeed would be unchanged.

In the real world there is a thing called the accelerated stall that can happen when high wing loads are applied, as in such a turn. The stall would occur at a higher airspeed than it would in level flight and might do so in this scenario.
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Last edited by kaptondave; Sep 16, 2012 at 05:13 PM.
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