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F-22 Crash in Florida #5430256 05/15/20 09:06 PM
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ZeeOSix Offline OP
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Re: F-22 Crash in Florida [Re: ZeeOSix] #5430260 05/15/20 09:09 PM
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IMSA_Racing_Fan Offline
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Inherently unstable airframe + flight control computer system failure is my first guess.

Re: F-22 Crash in Florida [Re: IMSA_Racing_Fan] #5430295 05/15/20 10:18 PM
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ArrestMeRedZ Online Content
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Originally Posted by IMSA_Racing_Fan
Inherently unstable airframe + flight control computer system failure is my first guess.


Possible, but since they have had the kinks associated with that worked out for the last 40 years, I'm guessing it was something else.

The last big problem associated with an unstable airframe that was computer controlled was the F-16 aux power unit activation issue in the late 70s/early 80s that caused an aircraft pitch over. The less sensitive among us took to calling F-16s lawn darts at the time.

Re: F-22 Crash in Florida [Re: ZeeOSix] #5430321 05/15/20 11:16 PM
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The F-22 crash that happened today was only the 5th crash in it's history. Crash #1 was on a development model of the F-22. Crash #2 (which I read the official AF crash report and saw all the details) was due to the test pilot doing maneuvers that he couldn't recover from. He was killed when he ejected way above the safe envelope. Two of the five pilots were killed (one ejected and one didn't), and the other three pilots ejected safely.

https://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor#Accidents

BTW ... the air frame isn't "unstable".

Re: F-22 Crash in Florida [Re: ZeeOSix] #5430347 05/16/20 01:00 AM
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ArrestMeRedZ Online Content
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Originally Posted by ZeeOSix
BTW ... the air frame isn't "unstable".

Like just about every fighter since the F-16 (and the B-2), the F-22 has negative aerodynamic stability, commonly referred to as "unstable".

Re: F-22 Crash in Florida [Re: ZeeOSix] #5430357 05/16/20 02:11 AM
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Maybe a large bird ingestion.

Re: F-22 Crash in Florida [Re: ArrestMeRedZ] #5430359 05/16/20 02:19 AM
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Originally Posted by ArrestMeRedZ
Originally Posted by ZeeOSix
BTW ... the air frame isn't "unstable".

Like just about every fighter since the F-16 (and the B-2), the F-22 has negative aerodynamic stability, commonly referred to as "unstable".


Define "unstable". Every see an F-22 perform at an air show?

Re: F-22 Crash in Florida [Re: ZeeOSix] #5430364 05/16/20 02:59 AM
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Re: F-22 Crash in Florida [Re: ArrestMeRedZ] #5430365 05/16/20 03:15 AM
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WyrTwister Offline
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Originally Posted by ArrestMeRedZ
Originally Posted by ZeeOSix


BTW ... the air frame isn't "unstable".


Like just about every fighter since the F-16 (and the B-2), the F-22 has negative aerodynamic stability, commonly referred to as "unstable".


Yes , that is what I have read .

A stable aircraft will tend to keep flying , pointedy end first , if there are no control inputs / correction . Like a paper airplane . But this can be a disadvantage for an air superiority fighter . Which needs to be able to make quick & sometimes violent maneuvers .

Far as I know , these " new " fighters are all fly by wire control systems . The pilot controls do not operate the control surfaces . They generate inputs to the electronics of the control system . The electronics ( when operating correctly ) generate outputs which in turn activate the control surfaces .

If the electronics are having a bad day , the plane does not have inherent stability ( like a good paper airplane ) and would / will have a tendency to swap ends with it self / go out of control . Without the electronics ( which can react faster than a human ) the plane is un-controlable / un-flyable .

None of this is from personal experience . I am not a pilot .


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Re: F-22 Crash in Florida [Re: ZeeOSix] #5430376 05/16/20 04:37 AM
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skyactiv Online Content
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Could be human error.


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Re: F-22 Crash in Florida [Re: ZeeOSix] #5430389 05/16/20 05:42 AM
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Luckily he ejected and wasn’t injured.

Re: F-22 Crash in Florida [Re: ZeeOSix] #5430407 05/16/20 06:38 AM
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Astro14 Online Content
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It crashed 12 miles from Eglin, so it was returning to base, not maneuvering.

That suggests mechanical/airplane problem. Not pilot error.

The airframe is unstable. Without fly by wire control, it lacks stability. This gives it exceptional maneuverability. The stability is added back in electronically. Just like the F-16 (only a couple of generations better).

It is flyable without positive static stability. But it’s squirrelly, and hard to fly. Not like an airliner or light aircraft, both of which have positive static stability.


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Re: F-22 Crash in Florida [Re: ZeeOSix] #5430479 05/16/20 08:25 AM
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Not to guess but I honestly always have trouble imagining the skill level the skill the pilots have to fly the planes.


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Re: F-22 Crash in Florida [Re: ZeeOSix] #5430614 05/16/20 11:23 AM
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Luckily, the pilot ejected safely; he is the only person that knows right now. Speculation is like throwing darts, the incident investigation team will sort it all out. I lived in this area for 11 years while stationed at Hurlburt Filed; one thing not mentioned is this time of year is Egret mating season...pretty large bird. While I was down there, Mr. Baker, the airfield manager would drive around and fire 40mm blanks to scare birds away before they finally installed an automated system. Has anyone seen any video out in the wild yet, that might be interesting to look at.


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Re: F-22 Crash in Florida [Re: ZeeOSix] #5431030 05/16/20 11:32 PM
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BusyLittleShop Offline
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Originally Posted by ZeeOSix


BTW ... the air frame isn't "unstable".


It is "unstable" because the F22 CG (Center of Gravity) is aft to
the CL (Center of Lift) and the tail lifts to stabilize pitch whereas
the Me 109 the (Center of Gravity) is forward to the CL (Center of
Lift) and the tail down force stabilizes pitch...

[Linked Image]

You can take a stable wing like the Ford TriMotor and make it less stable or
more maneuverable by adding weight in the tail and thus bringing the CG
closer to the CL as Tex Johnson demonstrates...







Last edited by BusyLittleShop; 05/16/20 11:50 PM.

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