Forum: General F-22A Raptor forum

sferrin wrote:

em745 wrote:

cola wrote:

Cross section is part of it. The YF-23 appears to have a large cross section, but its similiar to the F-14 because its essemntially 2 engine nacelles with a fuselage "pod", sort of also like the SR-71.

The F-35s cross section is huge, and in continues on for majority of the ac's length. Its a big airplane, despite being shorter than an F-15, its got to be nearly the same volume as an eagle. So in truth, its cross section, plus volume. The volume of the Eurocanard isn't nearly as big as the F-35, and it doesn't have all of the 35s bulbous appendages here and there throughout the airframe. It also has fewer flight control surfaces than a -35.

There ain't no such thing as a free lunch, and cross section area typically means large volume, and volume = mass. Plus the -35 is packing a lot of iternal sensors/electronics that -16s and -15s aren't lugging around. It ain't rocket science about the weight of gen5.

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em745 wrote:

Here, does THIS help?

Sure it does, but I'm not sure how it helps you?
F15 is the blue one.

The thing is internal installations require more structure and volume then the content itself, which then adds to cross section.
If you can't figure that out, well...

Quote:

(That's it. I'm done feeding the animals.)

But animals are still hungry! Pls hurry. Very Happy

cola wrote:

Although the resulting drag coefficient may be lower than for separate external installations, the overall cross section (equally important piece of equation) is usually considerably larger than for the planes with external stores, so the actual value of total drag and supposed advantage of internal installations, is a very moot point.

F22 flies good cause it has two big engines, not because of internal installations.

In that case then, it's hard to really say without going through the actual numbers. Area is easy enough to compare (and while the F-35 seems pretty big, the 22 isn't really all that different from the F-15). Ext fuel tanks are probably the biggest problem for 4th gen though, especially when you start packing multiples on them onto the planes.

With internal weapons, you also have the ability to maintain a constant external profile, which makes things much easier when trying to account for wave drag. You no longer have to compromise or build around one specific load out.

Also, those engines certainly do help, Like I said before, the internal weapons were only part of the equation.

cola wrote:

em745 wrote:

Here, does THIS help?

Sure it does, but I'm not sure how it helps you?
F15 is the blue one.

The thing is internal installations require more structure and volume then the content itself, which then adds to cross section.
If you can't figure that out, well...

The cross section of the two planes is clearly very similar. The F-22 has a slight bit more hump to the back and lacks the centerline tunnel; the F-15 sticks out a bit on the corners of the air intakes, just about equalling the centerline tunnel, and its tail booms and horizontal tail seem to just about equal those areas. (Unfortunately I don't have a copy of Photoshop handy to count the colored pixels in each image, but I'd say the difference is less than 5%, if that. And I'm not entirely sure which would come out smaller.) Certainly even if the F-15 is the one with less area, the difference is smaller than even one external fuel tank or a a load of AMRAAMs and pylons would add to the F-15. Without which addition to the frontal area, the F-15 is helpless while the F-22 could potentially be fully armed. And that doesn't even account for the interference drag you have to add to the form drag of a plane with external stores, which becomes immense at transsonic speeds and up.

Maybe this would help you:

Three different models of Boeing 737, with vastly different internal carriage. Notice there's only one front view. That's because they all have the same frontal cross section. Amazing, huh? You don't need to increase frontal area to increase internal volume. Because area != volume. Or did you flunk 2nd grade geometry?

From: "Introduction to Aeronautics, a Design Perspective"

Bradley notes: “Perhaps the greatest irony for the tactical aircraft designer results from the fact that an aircraft designed to be the ultimate in aerodynamic efficiency throughout a performance spectrum is often used as a ‘truck’ to deliver armaments. Aircraft that are designed in a clean configuration are often used operationally to carry an assortment of pylons, racks, missiles, fuel tanks, bombs, designator seeker pods, launchers, dispensers, and antennas that are attached to the configuration at any conceivable location.”

“The carriage drag of the stores is often of the same order of magnitude as the total minimum drag of the aircraft itself. For example, the minimum drag of the F-16 aircraft is compared in Fig. 9.15 with and without the air-to-ground weapons load. It is readily seen that the store drags themselves present as large a problem to the aircraft designer as the drag of the clean configuration. Store carriage on modern tactical aircraft is extremely important, particularly as one approaches the transonic regime, where the interference effects of the stores and pylons are highest and most detrimental to performance.”

Edit: Add this:

From: Supersonic Characteristics of an Advanced F-16 Derivative Aircraft Configuration

"The longitudinal test results (g. 27) show that
lift, drag, and pitching moment are signicantly af-
fected by the tanks because they cause a lift loss
that increases slightly as lift increases. The lift loss is
nearly a constant increment for low angles of attack
(i.e., < 7 for M = 1:60 and < 5 for M = 1:80),
whereas the lift more rapidly decreases for higher an-
gles of attack. A positive shift in zero-lift pitching
moment and a decrease in static longitudinal stabil-
ity are associated with the tanks. This reduction in
stability is likely a result of
flow separation on the
wing. The supersonic drag increment for the tanks
is nearly 40 percent of the minimum drag for the
baseline configuration."

The above refers to 600 gallon tanks.

The configuration tested was a cropped delta.

river_otter wrote:

Amazing, huh? You don't need to increase frontal area to increase internal volume.

What does this have to do with F15 and F22?
F22 is clearly larger as a consequence of internal packing stealth requirement.
The trend in front cross section increase in stealth aircraft (not just US') is so obvious, that one needs to try really hard, not to see it.

Why LM didn't make F22 laonger then F15, but with smaller f.c.s. is something I'll leave you to figure out.

Quote:

...the difference is smaller than even one external fuel tank or a a load of AMRAAMs and pylons would add to the F-15.

Well first of all, you can't be serious about making a percentage estimates from a picture like this one? Very Happy

Second, what the external fuel tanks have to do with anything?

"Second, what the external fuel tanks have to do with anything?"

I don't know, maybe the ability to do actual missions in real world scenarios.

cola wrote:

river_otter wrote:

Amazing, huh? You don't need to increase frontal area to increase internal volume.

What does this have to do with F15 and F22?

It flat out refutes your earlier idiotic statement, "The thing is internal installations require more structure and volume then the content itself, which then adds to cross section." Clearly, increased volume for internal space does not inherently add to cross section. You just put internal stores behind things that are already there.

Quote:

F22 is clearly larger as a consequence of internal packing stealth requirement.
The trend in front cross section increase in stealth aircraft (not just US') is so obvious, that one needs to try really hard, not to see it.

No, once again you're wrong and it's likely you're the only person on these forums who can't see it. The F-22 (to the extent it's cross section is larger at all, if it even is) is primarily larger in the hump of the dorsal surface. Which is due entirely to the need to use serpentine intake ducts to hide the engines. The internal missile carriage simply takes advantage of empty space under the air tunnels, where they had to have to arch up, inwardly, and over, to block the view of the engines from the front. Look at any frontal picture of the F-22. Do you see a single structure poking out beyond the outline of the air intakes that hides a missile behind it? (And if you do, get your eyes checked.)

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Why LM didn't make F22 laonger then F15, but with smaller f.c.s. is something I'll leave you to figure out.

Because the fuselage cross section, as with any other fighter, is determined almost entirely by the air intakes and radar. Cross-sectional area established, they used existing space behind other needed structures to stash weapons. There was plenty of space; they didn't need to make it longer. Trivial.

Quote:

...the difference is smaller than even one external fuel tank or a a load of AMRAAMs and pylons would add to the F-15.

Well first of all, you can't be serious about making a percentage estimates from a picture like this one? Very Happy

I can think of only one other thing someone like you could possibly be looking at to make estimates of silhouette areas besides silhouettes of the planes. But it's dark in there and smells bad. I'll leave that to you to pull your head out. Laughing

Quote:

Second, what the external fuel tanks have to do with anything?

Fine, leave off the fuel tanks. The same would still hold true for six AMRAAMs, two Sidewinders, and the pylons the F-15 (unlike the F-22) would need in order to carry them.

river_otter wrote:

Clearly, increased volume for internal space does not inherently add to cross section.

Clearly...but it does so in reality due constrains of weapon deployment requirements, weight balance, etc, etc...
Just because it's possible theoretically, doesn't mean it's so in reality.

Quote:

Because the fuselage cross section, as with any other fighter, is determined almost entirely by the air intakes and radar.

Yea well, there's the world of difference between "almost" and "entirely" and that's exactly where the stealth comes in.
Besides, it's obvious the F22 is bigger, with smaller radar array and smaller intakes then the F15.

Quote:

I can think of only one other thing someone like you could possibly be looking at to make estimates of silhouette areas besides silhouettes of the planes. But it's dark in there and smells bad. I'll leave that to you to pull your head out. Laughing

Good to see you have manners of a "gentleman", so don't come yapping if you receive a similar treatment in return.

"
Good to see you have manners of a "gentleman", so don't come yapping if you receive a similar treatment in return."

This coming from one of the biggest trolls on any board who regularly belittles poster after poster, trolling them regularly with his Euro fanboy garbage.

Forum: General F-22A Raptor forum

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