quesion about F22 speed-brakes

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nettles

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Unread post01 Aug 2020, 21:55

On commefcial airliners, the speed brakes have a lever but no pictures of fighter cockpits exist online with a speed brake lever apparent. I looked up further information and apparently the speed brake functionality is only on the joystick. Is this really the case? What a horrible functionality in a dog fight.
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outlaw162

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Unread post01 Aug 2020, 22:51

F-22 aside, in all the fighters I'm familiar with, the speedbrake 'switch' was on the throttle(s), not the (joy)stick....which is very HOTAS functional if you think about its purpose(s). Boyd used throttle idle and speedbrake simultaneously followed by a loaded rudder reversal to make his 40 second reputation, an ancient 'dogfight' move. If he had to reach for a airliner type lever/handle he might have been known as 50 second Boyd. :D

All the transport category aircraft I flew were equipped with a lever/handle speedbrake control as you describe (generally controlling certain spoiler panels), not associated with the thrust levers ('heavy speak' for throttles)....which is also very functional for this type....especially if you've got 4 thrust levers.
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nettles

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Unread post01 Aug 2020, 23:31

Thankyou for making that plainly clear. One last question, what about speed setting? On commercial airliners, this is set by a knob. On Fighter jets, is speed only set by a knob as well? If so, during a dog-fight, as soon as the fight is over, this would meen you would have to reset speed and re-apply thrust under a dialed in setting to avoid going down into enemy territory in the event of a flame-out caues by over stressing the engines. This to seems less effecient if that is the case.
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outlaw162

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Unread post02 Aug 2020, 01:22

Commercial airliner flying and fighter flying are basically two different universes, both however with some risk. Other than some aviation safety best practices, they have very little in common. Try "The High and the Mighty" and then read "Thud Ridge". :D
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krorvik

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Unread post03 Aug 2020, 07:31

nettles wrote:On Fighter jets, is speed only set by a knob as well? If so, during a dog-fight, as soon as the fight is over, this would meen you would have to reset speed and re-apply thrust under a dialed in setting to avoid going down into enemy territory in the event of a flame-out caues by over stressing the engines.


The digital engine controls on modern fighters won't allow the pilot overstressing the engine, so even in a dogfight, the pilot can trust the plane to stay in the air. Provided some fast and hot foreign object does not penetrate the airframe that is..

Modern jet engines are very reliable.
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35_aoa

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Unread post03 Aug 2020, 08:13

nettles wrote:Thankyou for making that plainly clear. One last question, what about speed setting? On commercial airliners, this is set by a knob. On Fighter jets, is speed only set by a knob as well? If so, during a dog-fight, as soon as the fight is over, this would meen you would have to reset speed and re-apply thrust under a dialed in setting to avoid going down into enemy territory in the event of a flame-out caues by over stressing the engines. This to seems less effecient if that is the case.


Nothing in a fighter is anything like the automation you would find in a transport cat aircraft. No FD, no intrusive auto throttles or automation for that matter. You set your speed with movement of your left hand on the throttles. Autothrottles are a thing in a very basic form, i.e. capturing a mach number generally speaking, but that is definitely not used tactically. In modern engines, you can be at MAX afterburner for a very long time and not have any worry about "over stressing" them. I've had many flights in my career that were mostly full AB, especially in my short few years flying the Viper. I might use auto throttles and baro alt hold transiting to and from where I am working, but other than that, I'm hand flying and there is nothing automated about it. Same for instrument approaches.....all 100% hand flown.

On the theme of engines, we don't use thrust reduction for anything. You can see EPR on a specific page on a DDI, but it isn't noted on the normal engine instruments, and it has no application in any phase of flight. Every field takeoff for us is full afterburner for example.
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nettles

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Unread post05 Aug 2020, 00:35

I was not aware of any of this. Didnt know HOTAS meant HOTAS/BRAKE. If modern electeonocs wont allow the overstressing of engines, and a bad angle of attack exist in a dog-fight; the electronicspeed limit can be permanantly disabled to allow unrestricted increase, right? Also, does afterburner always glow red? Ive seen pictures of flame colors varying from green, blue all the way to absolute pink even. Also, is flame visible at Full Military thrust? Sorry for spelling. Utilizing the cell phone to text since my Land internet hates me.
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35_aoa

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Unread post05 Aug 2020, 05:19

Most modern Western fighter engines use some form of FADEC. Such an engine control will generally prevent you from exceeding any limits, and will also automatically reduce thrust or even shut the engine down if certain conditions exist. Not common at all, but it is pretty idiot proof. As for the flame color, afterburner creates that effect. MIL power will not, though on a dark night looking right up the tailpipes, you can generally see the glow of the turbines/hot section. As for afterburner color variance, different engines burn at different temps and have different flow patterns, hence the difference in color.
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Unread post05 Aug 2020, 13:08

Glowing hot nozzle and exhaust up through roughly the :45 mark. That’s not ab and you’re not seeing the turbines; engine runs at higher rpm and temps for STOVL flight.

https://r.search.yahoo.com/_ylt=AwrDQyn ... _PkobuY0U-
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zhangmdev

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Unread post05 Aug 2020, 13:46

nettles wrote:... the electronicspeed limit can be permanantly disabled to allow unrestricted increase, right? ...


No, those limits cannot be disabled, unless the flight control software is reprogrammed, usually for test purposes.
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Unread post05 Aug 2020, 15:00

nettles wrote: If modern electeonocs wont allow the overstressing of engines, and a bad angle of attack exist in a dog-fight; the electronicspeed limit can be permanantly disabled to allow unrestricted increase, right?

I assume you are referring to the Full Authority Digital Engine Control (FADEC) computers limiting engine speed due to "bad AoA"? If that is the case, it is a non-issue. Engines have been designed to be extremely tolerant of airflow disruptions at high AoA and airframes are designed to keep air flowing into the engine as well.
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Unread post05 Aug 2020, 18:25

Comparatively speaking, Harrier has fairly complex engine RPM and JPT (jet pipe temp) limiting functions. It operates at a variety of engine RPM/temp ‘datums’ depending on whether or not one is in a TO/Landing configuration, the nozzles are down beyond a prescribed angle, the water injection switch is off or on (and in the TO or the landing position), or the nozzles are aft and the jet is in up and away flight. Limiting may be turned off with a throttle push at the far end of throttle lever travel, or by manually flipping the limiter switch off (at the fwd end of the throttle quadrant).

It is rare to intentionally turn the limiter system off because doing so also removes the surge and over-temp protections that the DECS provides. The most typical occasion for doing so is during the descent in a heavy gross weight or high OAT Vertical Landing (VL) or combination of the two.
Last edited by quicksilver on 05 Aug 2020, 18:43, edited 1 time in total.
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nettles

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Unread post05 Aug 2020, 18:34

Alright, learned alot. Aerial-Warfare is now what I would consider a complex system.
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Unread post05 Aug 2020, 19:43

The mechanics of aerial warfare may be more complex and may have shifted to a more cerebral approach (F-22 and F-35) than the classic (which means outdated) 'seat of the pants' approach, but......

the goal is still the same, as some past grunt General aptly noted...."not to die for your country, but to make the other $OB die for theirs."

Philosophically, commercial airline flying is somewhat less harsh, though it has killed people occasionally.
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Unread post05 Aug 2020, 19:52

I think it has killed more people in recent decades than military aviation (focusing on people who were IN the aircraft shortly/immediately before time of death)
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