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UK F-35B Lost

Old 10th Dec 2021, 14:20
  #341 (permalink)  
 
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Originally Posted by gums
Salute!

Good poop, Buster. Thanks.

Only bad FOD I ever had was a chunk of ice that had built up in the intake and the end-of-rwy troops didn't see it. Ingested just after gear came up. Being a P&W F100 turbofan the chunk was diced and sliced, then mostly went thru the bypass ducting. Was in a Viper, so sucker struck the fan blades right under my seat, so it was very apparent something was awry. Secondly, when I retarded throttle I "felt" a vibration, so came back pronto for a heavyweight landing without touching the throttle again until rolling out. Had about 60 to 70 big compressor blades on first two stages missing chunks or severely bent. I don't know how much the damage reduced my power, but I had "enough" and did not tempt fate.

Can't imagine getting the F-35B off the deck without max specified power and some wind over the deck. And BTW, seems the USN did a "cold cat" test for their Cee model. Prolly find something over on the F-16 dot net F-35 forums.

Gums sends...
Sounds like good airmanship on your behalf.
I guess that you were in reheat on t/o and then cancelled reheat.
The F100 is a pretty sturdy engine.
I was used to working on military twin engine jets. For example, on Tornado, the FRC's said something like - in the event of an engine mechanical failure on take off, leave the engine throttle at its power setting and climb to safe height. Then throttle back to a safe setting and land as soon as possible.
Much like the F100, the RB199 was a (high) bypass engine and was pretty good at sending FOD down the bypass duct.
But hard body FOD did sometimes go into the small IP and even smaller HP compressor. And then you were in trouble.
NB. Never a pilot. Only an engineer by the way.
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Old 10th Dec 2021, 17:51
  #342 (permalink)  
 
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Salute!

Yeah, Buster, many of we colonists liked the Pratt motors as they were "robust". OTOH, the GE and Rolls motors were very high performance and lighter ( more thrust per pound). So I had a thousand hours in the Allison /Rolls fan in the A-7D with no problems, Great fuel consumption and so forth.

Best example of the fan bypass in the TF-41/Spey motor was ingestion of a flock of seagulls at Myrtle Beach. Motor coughed, belched and lost power. Pilot turned back and landed opposite rwy to show us the roasted birds!! Some were impaled on the bomb racks, but a few were lodged in the bypass duct. Suckers were toasty!

Gums recalls....
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Old 10th Dec 2021, 17:54
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Not to quibble, but for the record: The Tornado drill for an engine failure on take off after decision speed was:

Throttles (note the plural) …..Combat
Landing gear…………………..Up
External load…………………..Jettison if necessary

And once at a safe height and speed shut down the affected engine.

NB Never a pilot or an engineer, only a navigator.
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Old 10th Dec 2021, 18:34
  #344 (permalink)  
 
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Originally Posted by Buster15
On a typical modern GT, with a pressure ratio of over 25/1, a surge would happen incredibly quickly.
Certainly significantly faster than the normal FADEC data refresh rate of around 5 to 10Hz. And there is then the matter of the IGV/VGV/BV response time.
Some thread drift here, but having worked modern FADECs, that's not entirely true. Modern FADECs have surge detection/recovery logic that was completely lacking in the older hydro controls, so surges can be dealt with far more effectively. Further, the update rate varies dramatically depending on the particular FADEC function. We break the FADEC down into 'major frame' and 'minor frame'. Major frame means the FADEC has done pretty much everything it can do every major frame (there are sometimes a few engine monitoring functions that don't happen every major frame, but they are strictly things that don't in any way actually affect the actual engine control). Major frame update rates are typically around 200 milliseconds (e.g. 5 Hz). The more time sensitive tasks are done up to once per 'minor frame'. Depending on the task, it may happen once per minor frame, once every two or four minor frames, all the way up to once per major frame. For example, the fuel metering valve position command is updated every minor frame. Not familiar with the newest crop of Pratt FADECs, but on the modern GE FADECs the minor frame is 15 milliseconds (~66 Hz).

In short, modern FADECs can deal much faster and more effectively with a surge. However if the surge was caused by mechanic damage (e.g. FOD) - rather than a temporary airflow disruption, it may not matter.
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Old 10th Dec 2021, 18:46
  #345 (permalink)  
 
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Originally Posted by gums
Salute!

Yeah, Buster, many of we colonists liked the Pratt motors as they were "robust". OTOH, the GE and Rolls motors were very high performance and lighter ( more thrust per pound). So I had a thousand hours in the Allison /Rolls fan in the A-7D with no problems, Great fuel consumption and so forth.

Best example of the fan bypass in the TF-41/Spey motor was ingestion of a flock of seagulls at Myrtle Beach. Motor coughed, belched and lost power. Pilot turned back and landed opposite rwy to show us the roasted birds!! Some were impaled on the bomb racks, but a few were lodged in the bypass duct. Suckers were toasty!

Gums recalls....
Yea Gums, back in the day the saying (at least on the commercial side) was that Pratt engines surged easily, and could happily surge all day long without doing any real damage. GE engines hardly ever surged, but if it did it was a light bulb - you removed and threw it away and installed a new one.
However, around 1990 that sort of changed - the new Pratt engines still surged on a regular basis, but now the surge might well break them, while GE engines still seldom surged, but if they did it usually didn't hurt them. It took until the early 2000's for Pratt to come out with a fix for the surge problems with the PW4000 - and it involved a complete redesign of the HP compressor (and a very expensive mandatory retrofit to a fleet of several thousand engines).
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Old 10th Dec 2021, 18:53
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Originally Posted by Timelord
Not to quibble, but for the record: The Tornado drill for an engine failure on take off after decision speed was:

Throttles (note the plural) …..Combat
Landing gear…………………..Up
External load…………………..Jettison if necessary

And once at a safe height and speed shut down the affected engine.

NB Never a pilot or an engineer, only a navigator.
Quite correct. I was of the assumption that take off was at Max reheat. So you are right about going into combat.
Being a navigator certainly trumps an engineer by a big margin.
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Old 10th Dec 2021, 18:56
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Originally Posted by tdracer
Some thread drift here, but having worked modern FADECs, that's not entirely true. Modern FADECs have surge detection/recovery logic that was completely lacking in the older hydro controls, so surges can be dealt with far more effectively. Further, the update rate varies dramatically depending on the particular FADEC function. We break the FADEC down into 'major frame' and 'minor frame'. Major frame means the FADEC has done pretty much everything it can do every major frame (there are sometimes a few engine monitoring functions that don't happen every major frame, but they are strictly things that don't in any way actually affect the actual engine control). Major frame update rates are typically around 200 milliseconds (e.g. 5 Hz). The more time sensitive tasks are done up to once per 'minor frame'. Depending on the task, it may happen once per minor frame, once every two or four minor frames, all the way up to once per major frame. For example, the fuel metering valve position command is updated every minor frame. Not familiar with the newest crop of Pratt FADECs, but on the modern GE FADECs the minor frame is 15 milliseconds (~66 Hz).

In short, modern FADECs can deal much faster and more effectively with a surge. However if the surge was caused by mechanic damage (e.g. FOD) - rather than a temporary airflow disruption, it may not matter.
Appreciate that. Thank you.
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Old 10th Dec 2021, 19:06
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Quick (off topic question), is this what a surge would look like? F-18 departing Leeming yesterday afternoon. Returned shortly thereafter having dumped fuel and prepped for a cable engagement which was not needed in the end.


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Old 10th Dec 2021, 23:30
  #349 (permalink)  
 
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F-18C Engine Surge Series: https://i1.wp.com/theaviationist.com...-bianco_lr.jpg

ZOOM: https://i2.wp.com/theaviationist.com...ssor-surge.jpg

TEXT: https://theaviationist.com/2011/08/22/flameout/

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Old 10th Dec 2021, 23:43
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Thank you SpazSinbad. Much appreciated, looks exactly like what was seen.
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Old 11th Dec 2021, 00:58
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I had not considered that consequence after an incident on the ramp or with a catapult ! So a pilot might be launched a few degrees port of the the axis of the ships motion for precisely this reason?
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Old 11th Dec 2021, 01:38
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Salute!

averow
Not being a nasal radiator, but talking and working with some.....
The deal is wind over the deck, and the path of the boat does not have to be aligned as you may think. So the angled deck is a good thing if you have a cold cat or motor problem on the roll. Have to get a true nasal radiator to confirm.

Gums sends...
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Old 11th Dec 2021, 02:25
  #353 (permalink)  
 
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The CVN 'steams' along a steady course into wind, creating WOD Wind Over the Deck. One may see the four catapults are not exactly aligned along the 'steaming path', so there is usually a slight crosswind component during catapulting. The maximum crosswind is determined for each aircraft during initial testing ashore (when wind more or less in correct direction for the test) then on a carrier(s) before that aircraft becomes qualified to operate from a carrier. For example the F-35C had a lot of tests for CVN carrier qualification as well as the F-35B for various decks.
Flight Operations | The Skyhawk Association & https://skyhawk.org/sites/default/fi...eck-layout.jpg
For the F-35B it is easier for the ship axis to be aligned to STO path however it may not always be exact - one would have to see overhead photos and the take off path etc for each F-35B flat/ski jump deck. On a CVN the landing path (angle deck) is 9 degrees so an approaching aircraft is always nibbling left/right to correct for the centreline which is always moving from left to right during the approach. Again there is a crosswind limit for each aircraft type then limits for weather generally and perhaps pilot skill or the LSO just has had enough. :-)

Last edited by SpazSinbad; 11th Dec 2021 at 02:32. Reason: add F-35B STO deck txt
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Old 11th Dec 2021, 22:11
  #354 (permalink)  
 
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Not forgetting that "wind direction and speed" is a concept, rather than a fact. Look at an anemograph trace on a lively day..

Met. will report xx knots, gusts yy/, direction zzz, but apart from yy these are averages over a long period compared with the length of time to launch, be it CAT, ramp or anything fancy. After decision time nobody on God's earth knows the parameters in the next couple of seconds. The only controllable is ship's course, which might be a judgement call or might be dictated by the tactical situation.

Or, from a Metman's point of view, the pilot/ crew have my utmost admiration.

As an aside, I served at two stations where wind reversal was fairly common and UNPREDICTABLE except in the sense that we knew that it might happen, but not when.
Leeming and Nicosia. Fortunately OC OPS/ Flying and the Duty Pilot knew enough to know there were known unknowns.
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Old 11th Dec 2021, 23:45
  #355 (permalink)  

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I heard once from a sailor that, unlike for landbound aviation, their wind is steady?

Lack of orography, it's purely the pressure gradients making things happen. Save for the turbulent layer with limited thickness.

Last edited by FlightDetent; 12th Dec 2021 at 13:09.
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Old 12th Dec 2021, 03:55
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The CVN wind system MORIAH (they call the wind mariah) is described along with accuracy concerns etc in the six page PDF attached.

STRIKE TEST NEWS Air Test and Evaluation Squadron 23 Newsletter 2013 LCDR Pat “WHO?” Bookey
"...The wind over the deck (WOD) is measured from three anemometers on the ship (FWD, STBD, and PORT). These three anemometers feed the Moriah System, which is the wind display in PriFly and the bridge that is used to drive the ship to get recovery WOD. The Moriah display from the Mini Boss station allows the different anemometers to be selected individually. The FWD anemometer is at the top of the navigation pole to the right of catapult #1. The PORT and STBD anemometers are at the top of the mast on the island on outriggers on the port and starboard sides...." http://www.navair.navy.mil/nawcad/in...ownload&id=767

Attached Files
File Type: pdf

Last edited by SpazSinbad; 12th Dec 2021 at 04:04. Reason: addJpg
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Old 12th Dec 2021, 07:43
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Given the habit of politicians rushing to make (often nonsensical) speeches about all things Defence in the UK I wonder who will draw the short straw to have to announce why the aircraft as lost..... or will it be buried for 18 months before slipping out in a report on Christmas Eve?
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Old 12th Dec 2021, 08:30
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I have only just hoisted in that the embarked Squadron was 617.

Any truth in the rumour that their motto is being changed to Avec moi le dιluge?
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Old 12th Dec 2021, 17:14
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Originally Posted by FlightDetent
I heard once from a sailor that, unlike for landbound aviation, their wind is steady?

Lack of orography, it's purely the pressure gradients making things happen. Save for the turbulent layer with limited thickness.
Beg to differ. That is not the whole truth. How does that generalisation explain "cats paws" caused by down gusts on calm open waters? In any caselack of obstruction is not confined to open water. One of my tasks was trying to optimise anemometer siting on RAF airfields, subject to ATC and OPS constraints. Unsurprisingly a lot of airfields are very flat with minimal obstruction, and we tried to put the anemo where the gust ratios were least. Partly because the wind has a non-zero vertical vector there is no escaping gustiness in winds of any consequence. Sods Law says that the anemo ends up in a less than ideal place for aircraft landings/ take-offs.

Gust-ratio is a different matter: the more built-up the airfield is, the higher the ratio of gust to average wind. Can exceed 2 : 1 in cities. That does not extrapolate downwards all the way to a 1 : 1 ratio at sea.

As to whether this really matters is an airmanship subject, and the biggest thing I have ever flown is a boomerang, so am not qualified.
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Old 12th Dec 2021, 17:42
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Thanks for confirming my suspicion, stemming from the debate observed above.
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