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UK F-35B Lost

Old 1st Dec 2021, 19:27
  #261 (permalink)  
 
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Originally Posted by aeromech3
I had resisted questioning the hypothesis that an engine intake blank was missed in the preflight: from my experience which includes civil versions of military jet engines: I would expect there is FADEC on the F-35, then during start, an over temperature, EGT, would have been avoided, but it would be in the high region and doubtful the FADEC would have continued the start; typically due the lack of mass airflow the N1 and N2 speeds would rise quickly and even if this blank only caused a partial airflow blockage, the engine would undoubtedly surge (reversal of airflow) before reaching any power level to commence a take-off roll.
I propose a loss of a sensory input to the FADEC such as that normally created by forward velocity is more likely, possible some pitot type blank/plug would have limited the engine thrust during the roll; an instance I had to investigate due an aborted take-off was post a fuel control change on an RB211, the rubber gasket of a transit blank had been inadvertently missed, for a sensor pipe connection and, as the post FCU change only called for a flight idle run it was not until the aircraft started its take-off roll, that the engine failed to make take off EPR.
I guess that you are referring to a P Total pressure input which would increase with forward speed.
That being the case, I would not expect P Total pressure to increase by that much because forward speed would not be that high for this type of take off?
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Old 1st Dec 2021, 23:54
  #262 (permalink)  
 
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Following an ejection, do any of the aircraft systems make inputs to control surfaces or engine thrust?

Mjb

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Old 2nd Dec 2021, 00:19
  #263 (permalink)  
 
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Of course.
CMD avoid school/orphanage/hospital\\
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Old 2nd Dec 2021, 00:21
  #264 (permalink)  
 
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Some of the 'red bits' may have come from the ejection seat bits, the parachute box for example?

F-35 MB US16E Ejection Seat Tests 1-8 Slow Motion Long Play [10min - Timely SWEET Child]



Last edited by SpazSinbad; 2nd Dec 2021 at 00:34. Reason: add JPG/txt
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Old 2nd Dec 2021, 01:29
  #265 (permalink)  
 
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Salute!

@ Mickjoe......
The F-16 flight control system remains operational after an ejection unless its failure was the reason to punch out. When the EPU running and residual hydraulics, the sucker will maintain wings level and finally reach the AoA limit and continue. One plane did that and only had one broken main gear upon "landing". Was an aborted dead stick attempt and pilot decided to get out.

We also had anoyther one when the motor went tits up and the family model folks had a fee seconds to coordinate their ejection. The instructor said it was intersting to look down between his legs while in the chute to see the plane continue st ahead and finally hit the desert.

Gums sends...
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Old 2nd Dec 2021, 01:55
  #266 (permalink)  
 
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Buster 15 "I guess that you are referring to a P Total pressure input which would increase with forward speed.That being the case, I would not expect P Total pressure to increase by that much because forward speed would not be that high for this type of take off?"
Most modern jet engines would have a temperature sensor, static and dynamic port in their intake, for fuel control and EPR but not necessarily for indication.
Though a classic EPR case would have been Air Florida Flight 90 crash (note: I'm not calling it an accident).
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Old 2nd Dec 2021, 10:02
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Originally Posted by aeromech3
Buster 15 "I guess that you are referring to a P Total pressure input which would increase with forward speed.That being the case, I would not expect P Total pressure to increase by that much because forward speed would not be that high for this type of take off?"
Most modern jet engines would have a temperature sensor, static and dynamic port in their intake, for fuel control and EPR but not necessarily for indication.
Though a classic EPR case would have been Air Florida Flight 90 crash (note: I'm not calling it an accident).
Thank you.
Yes, I do understand that modern gas turbine engines have very sophisticated control laws and schedules, based upon a series of data inputs, both static and dynamic.
But normally, these would have been designed to be fail safe, such as having duplicate probes or sensors and in the event of an anomaly, these would revert to safe values.
This would be especially important during the critical take off phase.
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Old 2nd Dec 2021, 14:12
  #268 (permalink)  
 
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Originally Posted by Fortissimo
Quite, but there is a big difference between an ejection at 30,000 ft and one at 30ft in where the aircraft impacts and how far it travels thereafter. COSPAS/SARSAT might have provided an indication of the point of seat separation, but that is all. As for the expected overwatch, some of that may be sub-surface (we won't know) and surface vessels are unlikely to be directly over the site. The point is that Wallace - or whoever briefed on his behalf - has removed much of the ambiguity that would have been helpful in delaying the efforts of other 'interested parties' to locate the wreckage.
it’s possible the Russians could just ask the Chinese who might have almost all the diagrams of the plane already
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Old 2nd Dec 2021, 16:58
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Originally Posted by SpazSinbad
Someone asked about QE ski jumpy & F-35Bs (can't find 'someone' post again). The PDF above has lots of info with this snippet in there also:
Carrier countdown 30 June 2014 Tim Robinson
“...Not your father’s ski-jump
The QE-class’s ski-jump, too, has been carefully designed and engineered from the beginning — drawing on BAE’s Harrier heritage. Says Atkinson: “We had to go back into the archives and talk to people who had actually been involved with trials with the Sea Harrier and Harrier to make sure we understood the history of ski-jump ramp development. The aircraft carrier ski-jump is a UK innovation and something the UK is very proud of.” The QEC’s ski-jump is longer (200ft) than the Invincible class (150ft) and designed so that the aircraft has all three (including the nose) wheels in contact right up until the point where the aircraft leaves the deck — giving positive nose wheel authority throughout. Additionally, the F-35Bs smart flight control system ‘knows’ when it is going up a ramp and will pre-position the control surfaces and effectors to launch at the optimum angle to avoid pitch-up or down....” http://aerosociety.com/News/Insight-...rier-countdown
_______________________________

Sea Breezes - Guy Norris -AVIATION WEEK & SPACE TECHNOLOGY/OCTOBER 26-NOVEMBER 8, 2015
"...the F-35’s automatic lift system control will make operations from the ramp simpler and safer, says Wilson [BAe Systems lead f-35B Stovl test pilot Peter “Wizzer” Wilson]. “It has become remarkably simple, thanks to the cleverness of the airplane,” he adds. For a ski jump takeoff the pilot lines up, advances the throttle and maintains alignment with the main nozzle fully aft. When the ramp is reached, rate sensors on the aircraft recognize the change in attitude and deploy the nozzles to the appropriate vectoring angle. Once airborne, weight-on-wheels sensors signal the flight control system to reconfigure the aircraft for up-and-away flight...."
Thanks Spaz - very interesting answer thank you. And it does explain what was going on with the rear nozzle during the launch. The coding involved in controlling that (which is just a tiny part of the mission!) must be horrendous, with the added burden of multiple catastrophic failure scenarios given all the electro-mechanical sensor inputs and high-load mechanisms required. Almost seems pointless to have made the F35 habitable...

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Old 2nd Dec 2021, 18:04
  #270 (permalink)  
 
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Originally Posted by armchairpilot94116
it’s possible the Russians could just ask the Chinese who might have almost all the diagrams of the plane already
Alternatively they could do what they were good at during the Cold War.
Find someone who has peripheral access to key material, who has no regard for security procedures and who is seriously compromised already.
Now who fits that bill? Oh yes, whoever leaked that video.
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Old 2nd Dec 2021, 19:40
  #271 (permalink)  
 
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Originally Posted by armchairpilot94116
it’s possible the Russians could just ask the Chinese who might have almost all the diagrams of the plane already
Tell me, is there a living to be made from being utterly deluded?

Asking for a friend.
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Old 2nd Dec 2021, 20:00
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Originally Posted by Auxtank
Tell me, is there a living to be made from being utterly deluded?

Asking for a friend.
It's only deluded cos we know they'll say no.
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Old 3rd Dec 2021, 04:25
  #273 (permalink)  
 
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Originally Posted by Auxtank
Tell me, is there a living to be made from being utterly deluded?

Asking for a friend.
Speaking of deluded...
Yep. I'm going to put myself out there and say - cause; Mechanical Failure.
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Old 3rd Dec 2021, 07:55
  #274 (permalink)  
 
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Originally Posted by LateArmLive
Speaking of deluded...
I must concede;
touché
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Old 4th Dec 2021, 11:09
  #275 (permalink)  
 
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Originally Posted by aeromech3
Buster 15 "I guess that you are referring to a P Total pressure input which would increase with forward speed.That being the case, I would not expect P Total pressure to increase by that much because forward speed would not be that high for this type of take off?"
Most modern jet engines would have a temperature sensor, static and dynamic port in their intake, for fuel control and EPR but not necessarily for indication.
Though a classic EPR case would have been Air Florida Flight 90 crash (note: I'm not calling it an accident).
Sorry guys, the fuel control system of any gas turbine engine requires 5 basic inputs for self control either by FADEC or the Fuel control unit itself. These are a reference of PT2 and TT2 for air density, N2 Rpm, Throttle position and PB (Combustion chamber pressure) to prevent engine stall during acceleration. Supersonic aircraft need one additional control factor and that is MA (Mach number) to prevent excessive air entering the engine intake when aircraft airspeed is above Mach.
All other parameters such as N1 Rpm, TIT, FF, PT7 or Oil Pressure are simply for indication to the pilot of the state of his engine EG N1 RPM or PT7-PT2 when converted to an EPR is used to inform the flight crew how much power the engine is producing with FF used as a cross reference. OIl pressure and TIT is simply to inform the aircrew on the state of the engine in regards to oil pressure and operating temperature. Some FADEC systems are designed with software to control any condition outside normal, by warning the aircrew and automatically retarding fuel flow to prevent engine over speeds and over temps and also relight the engine if it flames out during aggressive maneuvering or abnormal atmospheric conditions if throttle position is in flight idle or above.
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Old 4th Dec 2021, 12:23
  #276 (permalink)  
 
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Originally Posted by Techo27
Sorry guys, the fuel control system of any gas turbine engine requires 5 basic inputs for self control either by FADEC or the Fuel control unit itself. These are a reference of PT2 and TT2 for air density, N2 Rpm, Throttle position and PB (Combustion chamber pressure) to prevent engine stall during acceleration. Supersonic aircraft need one additional control factor and that is MA (Mach number) to prevent excessive air entering the engine intake when aircraft airspeed is above Mach.
All other parameters such as N1 Rpm, TIT, FF, PT7 or Oil Pressure are simply for indication to the pilot of the state of his engine EG N1 RPM or PT7-PT2 when converted to an EPR is used to inform the flight crew how much power the engine is producing with FF used as a cross reference. OIl pressure and TIT is simply to inform the aircrew on the state of the engine in regards to oil pressure and operating temperature. Some FADEC systems are designed with software to control any condition outside normal, by warning the aircrew and automatically retarding fuel flow to prevent engine over speeds and over temps and also relight the engine if it flames out during aggressive maneuvering or abnormal atmospheric conditions if throttle position is in flight idle or above.
​​​​​​
Firstly, not sure why you are saying sorry. Your post is interesting.
Probably the most important parameter on a very modern Gas Turbine engine as far as control would be Turbine Entry Temperature, or actual Turbine Blade Temperature in the case of optical pyrometer sensor (RB199 & EJ200).
That would be to limit fuel flow as the temperature reached a limiting value.
It would also provide for surge indication in the event of cooling flow interruption.
So, TIT assuming you mean Turbine Inlet Temperature is far more than just an indication to the pilot.
It would be an essential control parameter.
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Old 4th Dec 2021, 16:26
  #277 (permalink)  
 
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Ramp Too Steep?

I am no STO VL or F35 specialist but ex FJ Question;
surely at the start of the roll it must have been obvious there was little or no forward thrust? From the video he could have aborted half way up the ramp he was going so slowly.
With all the Harrier experience in the UK surely there must be some early go no go speed/power/accel point? Just asking….

Originally Posted by tartare
Genuine question.
You're the driver - and for whatever reason all engine temps and pressures look normal as you taxy to the departure point.
Do we know if this was a short rolling take off in STOVL mode or was it using the ski-jump?
How could you not see some sort of thrust anomaly as you powered up - just before rolling to take off?
You'd see it, hear it and feel it... wouldn't you?
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Old 4th Dec 2021, 16:43
  #278 (permalink)  
 
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Originally Posted by Auxtank
Tell me, is there a living to be made from being utterly deluded?

Asking for a friend.
Yes, but you must relocate to southern Florida.
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Old 4th Dec 2021, 18:01
  #279 (permalink)  
 
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As I said a while back with a serious thrust anomaly (even if for some reason not immediately noticed) the F35 would likely eject the pilot - as designed to - as soon as the 'wheels off the ground flag' switched the protections onto the 'low altitude, can't fly or hover' page.

It is curious that such a smart jet couldn't refuse or abort the take-off and save HMG a few quid but I'm sure they will have fished it out and filled it with dry rice shortly . .
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Old 4th Dec 2021, 21:21
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Originally Posted by Jetstream67
As I said a while back with a serious thrust anomaly (even if for some reason not immediately noticed) the F35 would likely eject the pilot - as designed to - as soon as the 'wheels off the ground flag' switched the protections onto the 'low altitude, can't fly or hover' page.

It is curious that such a smart jet couldn't refuse or abort the take-off and save HMG a few quid but I'm sure they will have fished it out and filled it with dry rice shortly . .
The auto-eject does not function as you state.

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