Aerodynamics for dummies

[RhinoCharging00 48]

Thank you for such an interesting and enlightening post. The stall section was pertinent to my Warthunder experience as I stall more than I should, its good to get a more detailed introduction to those flight behaviours. You also say English isn't your first language? That makes it even more impressive... Mucho respecto.

[OberstDackel 123]

As a certified dummy- this is not dumbing it down enough.

I think you glossed over the basics a little too quickly.

[Rapitor 10,702]

Which ones ? Name them I'll see what I can do

[OberstDackel 123]

Which ones ? Name them I'll see what I can do

I'd argue the wing desscription (leading edge, chord etc) requires a diagram.

A little more time needs to be spent on drag- how exactly the non-laminar flow/vortices create drag.

 

And I think you go into compressibility too quickly before covering subsonic aerodynamics.

Other than that- it's good. More colorful pictures for us dummies!

[Rapitor 10,702]

I'd argue the wing desscription (leading edge, chord etc) requires a diagram.
A little more time needs to be spent on drag- how exactly the non-laminar flow/vortices create drag.
 
And I think you go into compressibility too quickly before covering subsonic aerodynamics.
Other than that- it's good. More colorful pictures for us dummies!

[spoiler][/spoiler]
-This pic is already on the OP. I don't understand what more I should add then.

-I'll correct drag info right now

-I'll create a new section to cover sub-sonic, trans-sonic and super-sonic flows shortly before the compressibility part.

[JohnDeacon 19]

Right, its for dummies :crazy:

 

you had better made a riddle of the wing profiles :)s

[BristolBrick 435]

As a certified dummy- this is not dumbing it down enough.

I think you glossed over the basics a little too quickly.

OK: Here's the basics:

 

*Getting bombed is bad.

 

*You need engines on your planes.

 

*People must eat or they starve to death.

 

*Crashing is not good.

 

_____________________________________________________________________________________

 

Great post.

 

(Why can't we thank?)

Edited June 27, 2015 by BristolBrick

[Rapitor 10,702]

you cannot thank OP

[Sshadow2015 451]

Here a basic Video 

I got so many of these 
(it's started @ 1min as intro so. (i can't describe it)
How Planes Fly.


https://youtu.be/OopNRltg8gQ?t=1m
 

[Ottobon 19,138]

you cannot thank OP

Can you clear something up for me? i have seen explanations of induced drag as such, largely in regards to induced drag v weight in hard turns, its effect on energy retention etc.
 
[spoiler]

Full document
http://www.jetero.com/downloads/Effect%20of%20Weight%20on%20Drag%20and%20Airplane%20Performance.pdf


 
[/spoiler]
 
can you touch on this or similarly tell me off if its none sense or something, i highly doubt that but since your more qualified here. Have mentioned it before but i think possibly if all these equations are true then Induced drag has to be one of the lesser well explained parts of aerodynamics (for example check this post when i brought this subject up)

Edited December 2, 2015 by Ottobon

[Rapitor 10,702]

Sure.

 

I'll just go the long way for those catching up here.

 

The total drag of a plane is given by Drag = 0.5*C_d*rho*Area*V^2.

 

This C_d can be decomposed in many way, and for today, we will split it between induced (C_di) and parasite drag (C_d0):

 

Now, let's rewrite your parasite drag formulation, from:

C_di = C * W^2 / (rho * AR * V^2), to C_di = (C_l)^2/ (pi * AR * e). pi is pi, e the Oswald efficiency number, C_l the lift coefficient. (From here or any pic with "induced drag coefficient on google)

Let me now rewrite C_l: C_l = lift / 0.5 * AR * rho * V^2.

Let me rewrite lift: lift = mass * g (or more for turn, never lower than mass unless stall situation).

 

Putting everything together: (mass * g  / 0.5 * AR * rho * V^2)^2/ (pi * AR * e) = C_di

rewritting:  mass^2 * g^2 / (0.5^2 * AR^2 * rho^2 * V^2 * V^2 * pi * AR * e). Assuming that C = g^2/ AR^2 * rho * V^2 * pi * e, we find the initial formulation back. (Note that it makes C dependant on the speed)

 

In english words, the explanation might seem trivial: a heavier plane will require more lift (at equivalent speed) to stay in flight. More lift = bigger C_l = bigger AoA. Bigger C_l from previous equations directly shows you that you will induce more drag, and bigger AoA makes you plane more "tilted", hence enhancing the marginal vortex on the wing tip, which is related to the induced drag.

 

 

The "trick" to claim "higher mass = more induced drag" was to realize that the original (and proper) formulation of the induced drag relies on the C_l, which itself is linked to the mass of the plane. Hence the "induced drag depends on mass".

 

However, like I showed, the "Constant" K2 (or K3) used in the report are likely to be very specific to a certain study of the aerodynamics, and are not really constant, at least not if you consider that in the constant I pulled out you have a v^2 hidden inside.

 

I hope I covered the points here, if not just ask again, I'll be glad to help.

Edited December 2, 2015 by Rapitor

[cricket27 164]

I have never really understood this, but how exactly does prop hang work?

[CrazySpitfire 140]

Are you sure that's for dummies? I see academic subjects mostly.

[Rapitor 10,702]

I have never really understood this, but how exactly does prop hang work?

It works by the superiority of the machine over the human.

 

Prop hang is basically the fighter going vertical and aim at the limit of the stall.

 

The reason pilots cannot pull a real prophand IRL is because you can either keep your plane stable (no stall) or aim at a target, but not both. IG, you have the instructor that will comply to both: keep the plane out of stall, with respect to the circle imput for aiming.

Sim pilots (FRB) cannot prophang kill enemy pilots, because you simply don't have the "feeling" nor the capabilites to adjust exactly your plane to aim at low speed, without overdoing it and stalling.

 

Prop hang is the very addition of the instructor on that game.

 

Are you sure that's for dummies? I see academic subjects mostly.

The "level" of the subject doesn't matter as long as the guy can get a hold on it. You have "relativity for dummies", and gosh relativity is hell of an academic subject.

[Pony51 6,572]

Excellent post   :good:  (maybe get some real pilots out of it!)

 

Could you add section for Vx and Vy so players can learn how best to climb?

[Rapitor 10,702]

Excellent post   :good:  (maybe get some real pilots out of it!)

 

Could you add section for Vx and Vy so players can learn how best to climb?

Climb speed section ammended

[LegateImperator 21]

Great topic!

[Sshadow2015 451]

OP if you want you can add this in a spoiler ..

i think its great way of showing it.

https://www.youtube.com/watch?v=Gg0TXNXgz-w

[TheDoctor117 450]

Kerbal space program has taught me a lot about this.

[Serpiko82 7,875]

Great work Rapitor! Though there is a possible typo, where you state that transonic effects start showing above Mach 0.3. Maybe you meant 0.8?

[Rapitor 10,702]

It is intended.

Past mach 0.3 you are out of the inviscid assumption (you cannot neglect compressiblity anymore), thus you need to make the same assumptions as with transonic regime

[Scharlakatz 59]

This is rather stupid question, but WT (In RB I am meaning) it takes in the shape of wing you have? That's pretty neat.

[Rapitor 10,702]

On 26/10/2016 at 4:39 AM, xX_IrisHeart_Xx said:

This is rather stupid question, but WT (In RB I am meaning) it takes in the shape of wing you have? That's pretty neat.

Hi Sorry for the 3 month late answer (I have serious issue with filters, so I don't know when people posts into any thread I posted in as well).

 

Yes, wing polar is modelised in WT, which is why various planes have various CL_max.

[GeneralLee2000 73]

Great guide, even though I already knew most of it! It will be great for those who don't know this.

[SkyKnight2014 108]

Good thread makes good reading!

 

War Thunder is quite impressive to simulate certain aspects of flight and aerodynamics.

 

Some areas that have interested me in aviation is aeronautical meteorology and the atmospheric conditions producing and affecting flight commands and flight surfaces, especially when planning flights or flying in tough weather and/or unexpected flying weather conditions. When you are tasked on how to correct or adjust for safe flight or maximizing air speed or staying on course.

 

I.e.

• Air Turbulence
• Low-Pressure Pockets
• Wind Turbulence
• Jet Streams
• Funnels
• Cold/Warm Fonts
• Air Masses
• Air Velocities
• Wake Turbulence
• Clear Air Turbulence
• Microbursts / downbursts
• Wind Shears
• Low Altitude Oscillation Wind Flow
• Contrails and Vortices Effects and Causes
• Icing
• Thermal Condensation
• Head Winds
• Tail Winds

 

 

 

 

 

 

All in which affect flight commands and surfaces and how you proceed to final, its really a science and what makes good pilots land each time managing sustained flight at correct speeds and altitudes even AOA's.

 

For example assaulting flight parameters of an aircraft and behavioral aspects of an air- frame design and flight surfaces here is an example of that on a F-18 Fighter jet...

 

 

 

More here if interested............  https://en.wikipedia.org/wiki/Meteorology#Aviation_meteorology

 

Enjoy the study material its good book learnin! 

 

Edited February 5, 2017 by SkyKnight2014