Basic aero questions

Hi,

Regarding induced drag, I understand where it comes from-the horizontal element of the resultant lifting force due to the rear facing lift vector.

But what is this 'horizontal' element in relation to? The ground, mean chord line or the direction of travel?

What is the correct term for this plane?

Is it possible to have a 3D lifting aero shape (not something symmetrical) in which all the lift is perpendicular to the 'horizontal' plane, so that there is no induced drag?

Thank you,

Bob

No.

Hi,

Regarding induced drag, I understand where it comes from-the horizontal element of the resultant lifting force due to the rear facing lift vector.

 

But what is this 'horizontal' element in relation to? The ground, mean chord line or the direction of travel?

 

What is the correct term for this plane?

 

Is it possible to have a 3D lifting aero shape (not something symmetrical) in which all the lift is perpendicular to the 'horizontal' plane, so that there is no induced drag?

 

Thank you,

Bob

The induced drag is measured in the free stream direction, just as the lift is measured in the direction normal (perpendicular) to the free stream direction. In reality, what you're getting is a single force, angled backwards due to the 3D nature of the shape producing it.

The difference in angle between the free stream direction and the mean chord line is the angle of attack.

No, it isn't possible to produce lift without induced drag. On a fundamental level, you can't produce lift without changing the direction of the airflow, and the change in direction means you will be creating some drag.

Helium balloon in air?...

Probably not as that is a buoyancy thing rather than an airfoil, but a good try.

Thanks PAYR, that is exactly what I was looking for.  

The 'balloon' comment was meant to be flippant but thinking about it, once the balloon starts rising, it becomes aerodynamic.

The air will pass the top (& bottom) point & will be forced horizontally at that point, in radial directions. The resolution of those forces will be zero. So you could say it has zero drag horizontally.

As the air passes further around the balloon towards its 'equator', the forces tend more to the vertical & there there are components of vertical & horizontal force (drag) but again the horizontal components, resolve to zero.

Personally speaking, I think there is more reward to be had by grabbing a needle & bursting the damned thing...

Hi

Aerodynamic References.

Not the lightest reading material, but you might find these references worth every penny.

 http://200.17.228.88...fia/Hoerner.pdf       Download and save the pdf file.

http://www.sfte.org/...17-addendum.pdf

The more you look the more you see.

Take Care.

Charlie.

I disapprove of piracy. Thanks.

The 1st piece was published in 1965, the second link is to the official publisher's website. I believe in copyright too, but not to a crazy extreme.

Yeah, it is one of those horrible slippery slope dilemmas. Would I ever buy a new copy of Hoerner? Almost certainly not. So they haven't lost a sale. But... should the worker be denied the fruits of his labor?

Well Hoerner died in 1971, so that ship has probably sailed now 50 years later.

I suppose i could burn the money.

Well Hoerner died in 1971, so that ship has probably sailed now 50 years later.

UK copyright lasts 70 years after the author's death.

We had a copy of Hoerner at work (British Aerospace, Civil Aircraft Division) in the 1980s, and quite helpful it was too, even though it was many years after he wrote it.
 

This solar car was designed using Hoerner. We tested a few aspects of it using a 1/5 scale model on an 8x4 on the roof of a car.

https://www.amazon.c...a/dp/B07J5GR42L

The Evolution was designed using CFD by an ex F1 aero guy

http://new.aurorasolarcar.com/Cars

I have a question for the tech heads here:

Given the dirty-air-downforce issue with the current cars, would a blown diffuser manufacture the right kind of downforce to reduce the problem? 

If so, why hasn't it been discussed by the teams in the last few years?

an exercise on possibilities what can be done with the front wing

Will have to watch this a few more times, but thanks pierre. His youtube site has a few more interesting videos as well as this one.