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  #31  
Old 05-23-2007, 07:45 PM
chasingmars chasingmars is offline
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Quote:
Originally Posted by TMann View Post
All I was looking for as stated initially was some confirmation as to whether or not I was on the right track to reduce drag in this area.
Hmmm... I nearly posted this last night, got most of it written out, then figured I was just restating something that Marc had mostly said in debatably easier language for someone without a lot of engineering background in fluid mechanics. So I deleted it, but I'll put it here again as it may give a clearer idea of *why* it's not worthwhile.

You've basically got drag coming from a few places... induced drag which is inherent in generating lift, form drag, skin friction, etc. These three examples do however all affect the strake.

Be reprofiling the strake, you're making it a bit better at being an efficient lifting surface. Induced drag typically scales with the square of the lift coefficient, which means that when the lift coefficient is small, induced drag is really small. So since the strake doesn't produce much lift, it produces very little induced drag, and saving a few percent of this small amount is not likely to be noticable.

Parasitic drag (skin friction, form drag, etc) are not something you're really gain anything on... yes, we can debate whether keeping the flow laminar would theoretically reduce your parasitic drag, but, that's not going to happen because the flow over the strakes is not smooth to begin with, it's in the wake of the canard, so trying for laminar flow here would be more than an amatuer without a CFD PhD and a supercomputer could hope to acheive.

So, that's why, in my opinion, this wouldn't be a productive effort.

Which, Marc managed to say in one line ("For cruise flight in these aircraft, the lift coefficient is very low, and the drag is consequently pretty low, too.") - if you'll forgive me for being blunt, if you have the skill set to design the changes you were proposing, that would have been enough of a reminder.

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Originally Posted by TMann View Post
Your involvement in this topic is quite voluntary.
That should be cause enough to give pause, I for one value Marc's contribution. You may find him overly blunt and a little less than tactful on occasion, but I for one think his heart's in the right place. He's under no obligation to teach you, and if you don't like the way he puts his responses you can just ignore them (at your peril, he is, in my experience, very, very rarely wrong)
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  #32  
Old 05-23-2007, 08:13 PM
Marc Zeitlin Marc Zeitlin is offline
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Originally Posted by Dust View Post
That, my good sir, is what the internet is all about, the newby, the eagerness, the fresh ideas (to them), that is the fun of the internet.

to keep it alive and not squash it
While getting the same question over and over again from new, different people is mildly frustrating at times, especially when the information is easily findable in archives and google searches, it's not a big deal. You point them to sources of information, explain how to search and what to search for and hope that they will educate themselves. When they don't understand something after doing a bit of research, you help explain it to them. For me, the figurative look of "aha" understanding on their on-line faces when they get it (and MOST do) is what keeps me coming back.

That said, it's the people that have been around a long time, are NOT newbies, should be able to know better, but persist in making the same errors of form AND substance over and over and over again, as well as attempting to lead others down the path of ignorance and error, that tries the patience of those who do have an inkling of understanding.

I think even you, Mike, may have a vague clue as to whom I am referring. I've been using the internet extensively to facilitate communication since before you heard the word. It's not the newbies that are the issue here - it's people that persist in not knowing what they don't know, and don't want to know what they don't know, while thinking they do.
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  #33  
Old 05-23-2007, 08:42 PM
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Quote:
......as it may give a clearer idea of *why* it's not worthwhile.
....and clear it is Craig. Thank you for your contribution. I did not take into consideration the strakes existing in the wash of the canard.
....one free software service call for you.

Basically what I am getting from this is 'more esthetically pleasing to the eye ....but functionally...nada.'
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  #34  
Old 05-23-2007, 09:13 PM
Jason Heath Jason Heath is offline
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Originally Posted by TMann View Post

Basically what I am getting from this is 'more esthetically pleasing to the eye ....but functionally...nada.'
Ah shucks, you mean the soap is over! The main character gives up and the villan turns out to be a good guy after all. Oh well, American Idol is on next, see you tomorrow, same time, same...............
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  #35  
Old 05-23-2007, 09:55 PM
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Yes Jason.....The soap is over.
This one seems to have brought everyone out of the woodwork. To my count 20% of your posts since joining the forum over a year ago are right here on this very thread!

While I think Craig may have been able to understand what Marc was saying (due to his engineering background) I could not. I could however understand it in the terms in which he (Craig) restated it and I appreciate that effort.

'nuff said!
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  #36  
Old 05-23-2007, 10:15 PM
chasingmars chasingmars is offline
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Quote:
Originally Posted by TMann View Post
....and clear it is Craig. Thank you for your contribution. I did not take into consideration the strakes existing in the wash of the canard.
....one free software service call for you.

Basically what I am getting from this is 'more esthetically pleasing to the eye ....but functionally...nada.'
sorry, you missed ... while potentially affecting the centre of lift sufficiently to adversly affect predictable flight characteristics...

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  #37  
Old 05-23-2007, 10:24 PM
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Steve parkins Steve parkins is offline
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Quote:
Originally Posted by TMann View Post
....and clear it is Craig. Thank you for your contribution. I did not take into consideration the strakes existing in the wash of the canard.
....one free software service call for you.

Basically what I am getting from this is 'more esthetically pleasing to the eye ....but functionally...nada.'
i all most added that but its funner to just read.
i did mine just a smige off planes
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edited by steve for a good reason
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  #38  
Old 05-23-2007, 11:15 PM
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I wanted to sit this one out and see if anybody brought up the reason why the strakes are the way they are. So far nobody has mentioned the reason why it might be pointless to make an airfoil out of the strakes.

There's the canard out front of the strakes, messing up the airflow for whatever is behind the canard. So you'll have a hard time getting a laminar airflow mainly because the air is already in heavy turbulence before it even hit the strakes.

I would probably work on smoothing the air flow from the canard first before I even think about the stakes.

At least you are trying to do something about it!
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  #39  
Old 05-24-2007, 10:38 AM
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mtorzews mtorzews is offline
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Its fun to see that I can take 6 months off from this forum and return to the same arguments without missing a beat.

I'll say this again (cause last time was 6 months ago)

Be nice to Marc. He is very knowledgeable in the design of the aircraft. His arguments are sound and ripe with facts. You may not like his words, but his heart is always in the right place. He wants to keep you safe and keep you from wasting time.

Be nice to Dust. He has a creative mind and thinks outside the box. He challenges perceived "knowns", and tries to push the envelope. You may not like his persistence, but it is that persistence that ensures the argument is debated long enough for us all to learn. He always strives to include all and make everyone feel welcome to express new ideas.
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  #40  
Old 05-24-2007, 11:13 AM
Wayne Hicks Wayne Hicks is offline
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In reading older CPs, the flat strake tops were easier to build than curved ones. The main wings provided all the lift needed, and that lift was easier to quantify. RAF didn't need for the strakes to contribute lift. Thus, didn't have to quantify (test for) and factor in the lift contribution from the strakes.
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