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Old   February 5, 2010, 14:32
Smile Secret Aerodynamics of B2 Stealth
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I had invented a new aerodynamic concept to reduce drag. My friends and colleagues say that my concept has striking similarity to B2 Stealth Bomber (elevation) design. I think my concept is novel and I contacted Northrop Grumman but there wasn’t any feedback. So I am inviting your esteemed opinion in this regard. For details on my concept follow the link http://sites.google.com/site/highlyaerodynamicdesign/



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Old   February 5, 2010, 15:00
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Hi

I am no expert in the aerofoil design but curious to know, did you test your flow with different angles of attack and compare it with standard aerofoil design.

Thanks
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Old   February 5, 2010, 15:28
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I tested with 5 degree and 0 degree. But I didn't did a 100% matching to reality CFD analysis because of the lack of computing resources; basically I did a 2d analysis
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Old   February 5, 2010, 15:43
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1- Write your results in a paper and see if it can be published
2- Patent your design
3- Have you thought about manufacturing ?
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Old   February 5, 2010, 16:46
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1. The leading edge is very sharp. This will easily lead to stall at small attach angle.

2. You claimed : "pressure at top and bottom of trailing edge is almost equal. So there is less flow around tip from bottom to top at trailing edge. This will reduce vortex generated" This happens naturally to any airfoil, not particularly to your design, as Kutta condition. Wingtip vortex has to be 3D. how can you know this from a 2D design?

Last edited by bearcat; February 6, 2010 at 02:09.
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Old   February 5, 2010, 23:47
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Quote:
Originally Posted by Ahmed View Post
1- Write your results in a paper and see if it can be published
2- Patent your design
3- Have you thought about manufacturing ?
I am working on a paper in association with CUSAT professors. I have applied for a patent and it is in process. I am contacting companies for the help in manufacturing I would highly obliged if you could help me in this regard,
Thanks
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Old   February 5, 2010, 23:50
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Quote:
Originally Posted by bearcat View Post
1. The leading edge is very sharp. This will easily lead to stall at small attach angle.

2. You claimed : "pressure at top and bottom of trailing edge is almost equal. So there is less flow around tip from bottom to top at trailing edge. This will reduce vortex generated" This happens naturally to any airfoil, not particularly to your design. It's called "Kutta condition". Wingtip vortex has to be 3D. how can you know this from a 2D design?
Leading edge can be made blunt for varying angle of attack.

I have assumed the Kutta condition from pressure contour plot of post CFD.
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Old   February 6, 2010, 00:02
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Quote:
Originally Posted by dijinj View Post
I am working on a paper in association with CUSAT professors. I have applied for a patent and it is in process. I am contacting companies for the help in manufacturing I would highly obliged if you could help me in this regard,
Thanks
You are jumping too fast fellow, your new design concept has to be proven and discussed by many experts before the interested parties (turbine manufacturers, Boeing and other) apply for your patent. So, better to focus on your paper.
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Old   February 6, 2010, 00:13
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But still i am worried about the novelty of concept. Is it possible that B2 stealth might be derived from similar concept; please comment on this
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Old   February 6, 2010, 01:56
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Quote:
Originally Posted by dijinj View Post
Leading edge can be made blunt for varying angle of attack.
Then it is back to the ordinary airfoil, isn't it?

Just high school physics. If air pushes wing upward (lift), then the wing must pull the air downward. Air must have a downward acceleration. You now want to cancel it and gain the lift at no cost?

Last edited by bearcat; February 6, 2010 at 02:21.
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Old   February 6, 2010, 02:15
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even if front is blunt the rest of the body profile is cycloid or combination of cycloid. But I never heard cycloid is used as thickness function of any airfoil.
Also worth mentioning is that you can clearly see that my design closely match the trailing edge of a water droplet. Water droplet is usually considered as ideal aerodynamic design
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Old   February 6, 2010, 04:19
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Quote:
Originally Posted by bearcat View Post
Then it is back to the ordinary airfoil, isn't it?

Just high school physics. If air pushes wing upward (lift), then the wing must pull the air downward. Air must have a downward acceleration. You now want to cancel it and gain the lift at no cost?
The lift in airfoil is generated by pressure difference; the lower pressure in upper side of wing is due to higher velocity of air. I am only tryin to make vertical component of velocity zero at trailing edge. the total velocity at upper side is higher in my design too.
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Old   February 6, 2010, 07:10
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The leading edge is silly. The trailing edge reminds me of some Liebeck airfoils.

Liebeck, Robert H. and Ormsbee, Allen I., Optimization of airfoils for maximum lift, J. Aircraft, Vol. 7, No. 5, Sep.-Oct. 1970, pp. 409-415.


Liebeck, Robert H., A class of airfoils designed for high lift in incompressible flow, J. Aircraft, Vol. 10, No. 10, Oct. 1973, pp. 610-617.


Liebeck, Robert H., Design of subsonic airfoils for high lift, J. Aircraft, Vol. 15, No. 9, Sep 1978, pp. 547-561.

A patent is only worth the money you are willing to spend to defend it.
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Old   February 6, 2010, 08:25
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Thanks; I studied Liebeck airfoils documents from aiaa.org. But none of them mentioned horizontal velocity vectors or parallel velocity vectors (top and bottom) at trailing edge. or the squeezing effect because of this phenomena.
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Old   February 6, 2010, 08:49
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An airfoil with minimal trailing edge deviation as you mention your design has, will as you note produce less induced drag. However, in order to minimize the deviation at the trailing edge you will need an unnecessary long chord and this will give a heavier wing with a larger frictional drag. Optimum is not at one end here. Optimum is somewhere in between.

Inventing a new revolutionary airfoil shape is about the most difficult thing to do in aerodynamics. The problem of airfoil design is probably the most investigated problem in aerodynamics.
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Old   February 6, 2010, 09:00
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I know Air foil design has 100 years of research database. Nowadays no one uses a particular theory, but uses a combination of these and optimizes using CFD for best result in a particular application. so you can include my findings in the optimization stage if they are suitable for that application.
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Old   February 6, 2010, 09:48
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Airfoil optimization is also a subject which has been studied a lot. I'd recommend you to read through for example the VKI lecture series on aerodynamic shape optimization by John Vassberg from Boeing Phantom Works and Anthony Jameson from Stanford University (an icon in the CFD world) to get an overview of what just a few researchers have been working on in terms of aerodynamic shape optimization:

http://aero-comlab.stanford.edu/Pape...-Lecture01.pdf

http://aero-comlab.stanford.edu/Pape...-Lecture02.pdf
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Old   February 6, 2010, 10:27
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thanks I will read through VKI lecture series on aerodynamic shape optimization. I think that will be very helpful in developing my concept

I would be highly obliged if you could comment on the novelty, viability and practicality of my concept
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Old   February 6, 2010, 13:59
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"I am Working on a paper in association with CUSAT professors"

If your paper is accepted for publishing, You will get the answer to your questions.
By the way, what CUSAT does stand for?
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Old   February 6, 2010, 14:03
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CUSAT = cochin university of science and technology
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