Engineer
Major
I never claimed F-22 fly at Mach 3.2. You are using , which is a fallacy.
SDF Aerospace and Aerodynamics Corner
- Thread starter paintgun
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I never claimed F-22 fly at Mach 3.2. You are using , which is a fallacy.
MiG-29
Banned Idiot
F-22 won`t fly Mach 3.2 simply because it needs a variable geometry intake, it shows fixed geometry can not reach that speed.
MiG-29
Banned Idiot
F-111 is a quarter cone D shaped cowling moveable spike with translating and expanding spike.
F-15 is an air superiority highly maneuvrable fighter with variable geoemetry intake.
Su-27 is a highly agile air superiority fighter with variable geometry intake.
MiG-29 and F-14 also have variable geometry intakes.
external compression intakes have a Mach 2.5 limit, after that supercritical states reduce pressure recovery.
SR-71 and XB-70 used mixed compresion with external-internal compression.
MiG-25 is an interceptor and uses the same mixed compression intakes.
For you intakes do not have speed limit but they do
Pitot tubes work efficiently up to speeds of 1.6, fixed intakes with ramps like DSI, F-16-79 or F-22`s caret intakes are okay up to Mach 2.
F-16-79 has two ramps and bypass doors which makes it more complex than the F-16 simple single normal shock, so it is more in line with DSI, half cone axysymetric intake of F-104 and F-22`s caret fixed intakes)
Vertical ramps like F-4 are okay up to Mach 2.2
Horizontal ramps with variable geometry or translating spikes with external compression are okay up to Mach 2.5
Horizontal or vertical ramps 2d intakes or cones with mixed compression and variable geometry up to mach 3.
After that they use ramjets or scramjets.
DSI and F-104 fixed intakes are the same type just one is divertless and the other has a diverter, so same performance is expected
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Engineer
Major
Neither can F-14 and F-15 reach Mach 3 with variable-geometry. Merely adopting variable-geometry isn't going to magically make an aircraft go at Mach 3.
Engineer
Major
F-111 is a bomber, and the fact that its intake design is not repeated on a fighter aircraft illustrates what I've said about complexity and weight. Increase complexity such as an extra movable ramp also leads to increase in drag. These penalties cancel out advantages gained by improved pressure recovery.
J-10A is a highly agile air superiority fighter with variable-geometry intake. Yet, this intake got replaced by DSI. This says J-10B's performance is at least the same with J-10A, if not better. Indeed, we see that J-10A's variable-geometry inlet is of similar type as that of F-4D, and we do see DSI's performance being better than the inlet of F-4D. That's a fact.
Internal and mixed compression demand extremely good quality air flow or they will unstart. This is penalty. The fact these inlets aren't use on fighter aircraft speaks volume.
Nope. , meaning pitot intake can work at Mach 2. Your claim of "work efficiently" does not equate to a speed limit. There is no evidence that F-22's Caret inlets cannot function at over Mach 2.
As for DSI, it has better pressure recovery ratio than the ramps on F-4 at Mach 1.8. At Mach 2.0, the pressure recovery ratio of the two inlets are similar. Considering that F-4 can reach Mach 2.2, there is no reason why DSI cannot do the same. Your claim that DSI is limited at Mach 2 is merely your opinion, not supported by facts.
These are not inlets.
On the subject of scramjet, hypersonic test vehicles with scramjet use fixed inlet. This shows the speed limit that you claimed is solely an invention by you. What actually correlates with performance is the number of oblique shocks generated.
Nope, they are not the same type. The fact that one has diverter and the other is diverterless already tells you that they are fundamentally different and are not of the same type. Furthermore, the inlets on F-104 are 2D, whereas DSI is designed using 3D, this once again shows they are not the same type of inlets.
MiG-29
Banned Idiot
man the las statement prove you do not know anything about inlets.
F-104 has a half cone axisymmetric intake, that is not a a 2D, 2D intakes are the ones with wedges as ramps, F-4 and F-15 has 2D intakes.
DSI and F--104`s use isentropic shocks
The design principle for the bump is to design acompression surface similar to the cone flowdescribed above and use the known flow fieldsbehind conical shocks to achieve desirable results.The cone flow produces an isentropic compressionwhich is a multi-shock compression (figure 7). Thebump has pressure gradients which are spanwise andthese help to redirect the boundary layer
MiG-29
Banned Idiot
Neither can F-14 and F-15 reach Mach 3 with variable-geometry. Merely adopting variable-geometry isn't going to magically make an aircraft go at Mach 3.
it does, because fixed geometry can not reach mach 3
Engineer
Major
I take this to mean you are conceding that variable-geometry inlets have penalties, that F-16 speed limit is not Mach 1.6, that you have no proof for your claim that F-22 top speed is Mach 2. After all, if you truly think you are so correct, then you wouldn't need to nitpick two characters out of eight paragraphs and avoid addressing my post point-by-point.
As you've said, a half-cone axis-symmetric inlet, which is not a 3D inlet. Applying isentropic compression does not make DSI the same type of inlets as those used on F-104. Your arguments here are as silly as claiming a sphere is just a cube without corners. What this shows is that you are unable to find any support for your claim that DSI is inferior and now you are resorting to try anything that sticks, includes belittling by equating DSI to an ancient inlet design.
DSI is one classification for inlets, just like fixed-geometry as one type of inlet and variable-geometry as another type of inlet. DSI specifically refers to inlets that do not have diverter. The inlets on F-104 have diverter, thus they are not DSI and vice-versa.
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Engineer
Major
It doesn't. F-14 and F-15 both use variable-geometry inlets, and they both cannot reach Mach 3. This says speed of the aircraft depends on other factors, not whether the inlet geometry can change or not. What are those other factors? One being the engines, another being the airframe. However, speed is irrelevant, because what measures the performance of an inlet is not speed but pressure recovery.
Pressure recovery ratio correlates with the number of oblique shocks. The more numerous the shocks the better, because each shock can be made weaker resulting in less performance loss per shock. In fact, a fixed-inlet can be used above Mach 3 as long as it can create numerous oblique shocks, and this is exactly the approach taken on hypersonic test vehicles. If an infinite number of shocks can be created then it's even better, because the condition is close to isentropic. This is one reason why DSI has better performance than a variable-geometry intake with three shocks, because the former is close to isentropic while the latter isn't.
MiG-29
Banned Idiot
I take this to mean you are conceding that variable-geometry inlets have penalties, that F-16 speed limit is not Mach 1.6, that you have no proof for your claim that F-22 top speed is Mach 2. After all, if you truly think you are so correct, then you wouldn't need to nitpick two characters out of eight paragraphs and avoid addressing my post point-by-point.
As you've said, a half-cone axis-symmetric inlet, which is not a 3D inlet. Applying isentropic compression does not make DSI the same type of inlets as those used on F-104. Your arguments here are as silly as claiming a sphere is just a cube without corners. What this shows is that you are unable to find any support for your claim that DSI is inferior and now you are resorting to try anything that sticks, includes belittling by equating DSI to an ancient inlet design.
DSI is one classification for inlets, just like fixed-geometry as one type of inlet and variable-geometry as another type of inlet. DSI specifically refers to inlets that do not have diverter. The inlets on F-104 have diverter, thus they are not DSI and vice-versa.
2D ramps are wedges not cones, the rest what you say is pure fallacy no text says F-104 has 2D intakes.
Both F-104 and F-35 use isentropic shock, but DSI has no diverter while F-104`s has it