Art: Reference pic, 35 ton Endo/Exo atmospheric interceptor

[Tenacious-Techhunter]

In theory, you could have fat wings, being extensions of the missile pack of twelve missiles, now embedded in said wings.

Pack doesn't mean it can't be linear.

Too high drag for an air superiority interceptor... unless the missiles are just that tiny...

 

[wbnc]

In theory, you could have fat wings, being extensions of the missile pack of twelve missiles, now embedded in said wings.

Pack doesn't mean it can't be linear.

Too high drag for an air superiority interceptor... unless the missiles are just that tiny...

might be a good idea for A strike ship or a bomber though

 

[Tenacious-Techhunter]

The upshot of the Whitcomb Area Rule is that, as the wing increases in centerline axis area, the body has to shrink to compensate, to keep the same total area. Alternately, bulges before and after the wing can be used to compensate for the wings being added to an otherwise fixed fuselage shape. You should also try to change the centerline axis area as little as possible over the whole shape; a suggestion, for which, there are reasonable limits in what can be accomplished, many of them setting specific.

Having trouble converting text into a mental image on your description one of those odd mental lapses that occur on a regular basis.

The Whitcomb Area Rule can lead to some not-so-obvious consequences that are ultimately more efficient... Let’s see if I can dig up some pictures...


This is a very obvious example:

You’ll notice how the fuselage pinches in at the point most related to where the wing reaches full extension; this is to keep the total area of the centerline cross-section the same; it makes the wings less aerodynamically “bulgy”, by giving the air the wings displaced room to go somewhere.


A more subtle example:

This one is not very obvious, but now that you know what to look for, you can see it; the fuselage gently narrows until the wing tips reach full extension, then it stops, and bulges back out a bit, before it ultimately narrows again.


An even more subtle example:

This one is tricky, and requires a careful look at the 3-view drawing. You will see that the fuselage narrows in the vertical as the wings start just behind the cockpit, and then it widens in the horizontal just as the fully outstretched wings end.


An example where the rule is applied to the aircraft somewhere else:

“But the fuselage isn’t changing at all!”; no, it isn’t. But just as the trailing edge of the wing pops up, the nacelles behind the inner engines sprout, slowing the change in area; which is almost as important as eliminating it. If you can’t kill a change in area, at least slow it down.


Any time you see some weird bulge in an aircraft, and even in ocean-going ships, looking at the centerline cross-sections will help you understand why it’s there. It’s there to minimize the change in cross-sectional area along the length of the craft, which reduces the drag. It doesn’t have to be done obviously, either; I pointed out some really old examples because it’s most obvious in those examples how it was done; more modern examples make it either really subtle, or really inexplicable; but it does have to be done to properly optimize an aircraft.

 

[Tenacious-Techhunter]

In theory, you could have fat wings, being extensions of the missile pack of twelve missiles, now embedded in said wings.

Pack doesn't mean it can't be linear.

Too high drag for an air superiority interceptor... unless the missiles are just that tiny...

might be a good idea for A strike ship or a bomber though

It is appropriate wherever the specifications for that aircraft suggest it makes sense. For a bomber, I would go with a Blended Wing Lifting Body design... the extent to which that has “a fat wing” is open to debate.

 

[wbnc]

The upshot of the Whitcomb Area Rule is that, as the wing increases in centerline axis area, the body has to shrink to compensate, to keep the same total area. Alternately, bulges before and after the wing can be used to compensate for the wings being added to an otherwise fixed fuselage shape. You should also try to change the centerline axis area as little as possible over the whole shape; a suggestion, for which, there are reasonable limits in what can be accomplished, many of them setting specific.

Having trouble converting text into a mental image on your description one of those odd mental lapses that occur on a regular basis.

The Whitcomb Area Rule can lead to some not-so-obvious consequences that are ultimately more efficient... Let’s see if I can dig up some pictures...


This is a very obvious example:

You’ll notice how the fuselage pinches in at the point most related to where the wing reaches full extension; this is to keep the total area of the centerline cross-section the same; it makes the wings less aerodynamically “bulgy”, by giving the air the wings displaced room to go somewhere.


A more subtle example:

This one is not very obvious, but now that you know what to look for, you can see it; the fuselage gently narrows until the wing tips reach full extension, then it stops, and bulges back out a bit, before it ultimately narrows again.


An even more subtle example:

This one is tricky, and requires a careful look at the 3-view drawing. You will see that the fuselage narrows in the vertical as the wings start just behind the cockpit, and then it widens in the horizontal just as the fully outstretched wings end.


An example where the rule is applied to the aircraft somewhere else:

“But the fuselage isn’t changing at all!”; no, it isn’t. But just as the trailing edge of the wing pops up, the nacelles behind the inner engines sprout, slowing the change in area; which is almost as important as eliminating it. If you can’t kill a change in area, at least slow it down.


Any time you see some weird bulge in an aircraft, and even in ocean-going ships, looking at the centerline cross-sections will help you understand why it’s there. It’s there to minimize the change in cross-sectional area along the length of the craft, which reduces the drag. It doesn’t have to be done obviously, either; I pointed out some really old examples because it’s most obvious in those examples how it was done; more modern examples make it either really subtle, or really inexplicable; but it does have to be done to properly optimize an aircraft.

Okay now I know exactly what you were talking about...I remembered the F-102/f-104....More accurately my brain found the box it kept all that info in....and I had to keep from banging my head on the desk..an entire section of basic aircraft design had went awol...

the older designs do make it far more apparent ...looking at newer designs the changes are very subtle. mi 29, F-16, and f-22s do not look like they are "Pinched" at all but the aerodynamics they use do take the rule into account...or play little tricks to deal with the issue rather than have an extreme "wasp waist"

 

[Tenacious-Techhunter]

To be perfectly honest, I couldn’t really be sure you weren’t taking it into account, the effects are sometimes so subtle... but, sometimes, not being subtle about it leads to interesting results too. So, if nothing else, I wanted to be sure you had it in your bag of tricks.

The important thing is to take regular centerline cross-sections through your plane, and make sure you’re changing the total area as infrequently as possible. For supersonic craft, the centerline cross-sections should actually be folded about the yaw axis by the Mach Angle, and your intersecting areas checked that way. Of course, you’re doing art, so take this advice with the usual grain of salt. If nothing else, it’s a way to check whether designs are outright wrong.

 

[wbnc]

To be perfectly honest, I couldn’t really be sure you weren’t taking it into account, the effects are sometimes so subtle... but, sometimes, not being subtle about it leads to interesting results too. So, if nothing else, I wanted to be sure you had it in your bag of tricks.

The important thing is to take regular centerline cross-sections through your plane, and make sure you’re changing the total area as infrequently as possible. For supersonic craft, the centerline cross-sections should actually be folded about the yaw axis by the Mach Angle, and your intersecting areas checked that way. Of course, you’re doing art, so take this advice with the usual grain of salt. If nothing else, it’s a way to check whether designs are outright wrong.

To be honest ost of the time I am eyeballinng measurements and proportions based on what i see in potgraphs. and having walked around quite a few aircraft. I am just now begining to work on designs that are similar to real world aircraft so it's a learning process. The more costructive feedback and input I get the re I can alter my designs to look "right"

 

[Tenacious-Techhunter]

Creative uses of the Whitcomb Area Rule include finding interesting places to make up for differences in area far removed from where you might expect. The Tupolev is an interesting example of this; many would think the fuselage should be made bulgier, but instead they used those nacelles; it improves the fuel storage by placing it near the engines, and provides a place for landing gear to be stowed; and it’s not a function of the engines themselves, since the matching engines further out along the wing don’t need them. It was probably also easier to sell to their bosses at the time, since those bulges would have seemed outright stupid back then, instead of just confusingly weird but common; it also meant they could be more easily changed, or even removed, it they couldn’t figure out how to properly apply this “supposed new rule” to aerodynamics.

Oh, one last thing... Don’t apply the area rule to the engine, its intakes and its exhaust. Assume that the engine is a completely open cut-out, since, aerodynamically speaking, air “passes through it and out the other end”. Or, instead of treating it like a cut-out, treat it like “free bonus area”. This is one reason why planes like the F-22 go from svelte to boxy so abruptly; that portion of the change in area is free.