WING SWEEP WITH BELL LIFT DISTRIBUTION
04-30-2004, 12:41 PM
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WING SWEEP WITH BELL LIFT DISTRIBUTION
If I am building an ALL WING aircraft with a 40 in wing span using a bell shaped lift distribution of the sin 2.5 how does the designer figure the best root cord & tip cord length for the design?
Also, how does one figure the optimum sweep angle?
How does the designer correlate the BELL shaped lift distribution with SWEEP, & TWIST?
I have read all the information published in the five "On the Wing" articles concerning this subject but after reading them it has only left me with more questions than I had before I read them.
I understand that airfoil selection will affect the design & I have not selected the airfoils as of yet. Can anyone Tie this information together in a format that a normal person will understand?
I am thinking that there must be a logical order in the design process but I do not know were to start.
Also, how does one figure the optimum sweep angle?
How does the designer correlate the BELL shaped lift distribution with SWEEP, & TWIST?
I have read all the information published in the five "On the Wing" articles concerning this subject but after reading them it has only left me with more questions than I had before I read them.
I understand that airfoil selection will affect the design & I have not selected the airfoils as of yet. Can anyone Tie this information together in a format that a normal person will understand?
I am thinking that there must be a logical order in the design process but I do not know were to start.
04-30-2004, 01:35 PM
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RE: WING SWEEP WITH BELL LIFT DISTRIBUTION
The five articals reference the bell lift & the optimum bell with the least drag penalty, how do you tie the Twist, sweep, taper & Bell together
My question is basic, I want the sin 2.5, the least drag penalty.
What sweep angle is optimum?
What taper should be used?
I want good flying qualities without a large drag penalty...
I lack the knowlege of being able to tie the information together any scientific answer would be very helpful.
I understand that airfoil selection is important..
My question is basic, I want the sin 2.5, the least drag penalty.
What sweep angle is optimum?
What taper should be used?
I want good flying qualities without a large drag penalty...
I lack the knowlege of being able to tie the information together any scientific answer would be very helpful.
I understand that airfoil selection is important..
04-30-2004, 01:43 PM
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RE: WING SWEEP WITH BELL LIFT DISTRIBUTION
Your question is basic? LOL, I think you are overestimating our abilities... 
But thanks for the complement.
Have you found the Panknin twist formulas? There is also an Excell spreadsheet that brings all the calculations into one place. From there figure out what airfoils you want and the lift coefficients the root and tip should be working on. I'm not familiar with your sin 2.5 factor but the Panknin forumulas probably take that into account. Or if you understand how that factor fits into the scheme you can use the Panknin numbers to produce a stable planform and twist that supports your desired factor.
There's a link to the download at B'squared'Streamlines. You'll also need Excell or some other spreadsheet that can open Excell files. I think Open Office will do that if you need a free open source download.
PS: In reading over this again there was an online lift distrubution graphic application somewhere that would allow you to load in the root and tip chord and wing taper and wing twist and show the lift coefficients across the span. That's as close as I think you'll find to an interactive way to set up your desired bell curve. But it implies that you know what Cl's you need for the root and tip. But I think the Panknin setup to help you design a stable twist and sweep planform allied with the lift distribution graphic plus some knowledable guessing should get you into the ballpark of what you need. I don't have the link but try a google on some keywords. I seem to remember that it was not hard to find. It's just a simple java thing but it works.
But thanks for the complement.Have you found the Panknin twist formulas? There is also an Excell spreadsheet that brings all the calculations into one place. From there figure out what airfoils you want and the lift coefficients the root and tip should be working on. I'm not familiar with your sin 2.5 factor but the Panknin forumulas probably take that into account. Or if you understand how that factor fits into the scheme you can use the Panknin numbers to produce a stable planform and twist that supports your desired factor.
There's a link to the download at B'squared'Streamlines. You'll also need Excell or some other spreadsheet that can open Excell files. I think Open Office will do that if you need a free open source download.
PS: In reading over this again there was an online lift distrubution graphic application somewhere that would allow you to load in the root and tip chord and wing taper and wing twist and show the lift coefficients across the span. That's as close as I think you'll find to an interactive way to set up your desired bell curve. But it implies that you know what Cl's you need for the root and tip. But I think the Panknin setup to help you design a stable twist and sweep planform allied with the lift distribution graphic plus some knowledable guessing should get you into the ballpark of what you need. I don't have the link but try a google on some keywords. I seem to remember that it was not hard to find. It's just a simple java thing but it works.
04-30-2004, 01:55 PM
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RE: WING SWEEP WITH BELL LIFT DISTRIBUTION
Mr. Matthews I have visited that sight & am not sure what I am looking for...
Am I looking for D. Panknins formula?
Thanks for the info
Am I looking for D. Panknins formula?
Thanks for the info
