Flightradar 24 and Marine spotting odds and sods.

9.414

War Hero
The F-15s from Lakenheath have been showing up for about three weeks now. Not sure why the sudden change, they never used to.
There are some rather important US aircraft and people in the UK from yesterday. At a guess they came early and have been doing their recces. They will have shadowed and escorted AF1 into and around the airspace.
 

Boxer96

Old-Salt
Pressurise and condition the air in the cabin.

Bleed Air is taken from the Compressor Stages of the main engines (the bit before you put fuel in it and set it on fire so it’s essentially atmospheric air). Air heats up when you compress it (think bicycle pump getting hot) so it’s several 00 degrees at this point. It then goes through the pack where it gets cooled by heat exchangers etc and by partially depressurising it. Air cools when depressurised (think aerosol deodorant) so it is now too cold.

The Crew control cabin temperature and that operates what’s called Trim Air. This is a bit of the very hot air that gets diverted round the cooling bit and added back into the cold air downstream of the packs. This is the only real way of doing it (stand fast the 787) as the temperature of the bleed air and of that coming out of the pack is basically whatever you’re given.

This gives pressurised, temperature controlled air that is delivered to the cabin. It then flows from floor to ceiling, front to back. Some of it is recirculated through filters to reduce the Bleed Air consumption as taking air off the engines reduces their performance. This is the bit that Tin Foil Hatters get all twitched about but the reality is that the amount recirculated is very small, the filters are very high grade and can catch even virus size particles and the amount of fresh air and tge rate at which it is replenished together with the ceiling to floor flow makes the air arguably better quality than that in an operating theatre. The flight deck has a separate supply that doesn’t include recirculated air, primarily to ensure smoke removal procedures keep us alive.

The air going through the floor keeps cargo at a sensible temperature so your Y fronts don’t get blast frozen and also provides cooling for electronics etc.

The amount of air (rather than the temperature of it) is also a case of you get what you get and is designed to over deliver so the cabin will remain pressurised at all engine power setting, including one shut down. The pressurisation needs to be constant and this basically is designed to climb and descend the cabin at a gentle rate (about 500 and 300 fpm respectively as ears are more sensitive to increasing pressure (when descending) to about 8000’ Cabin Altitude. As the amount of pressurisation going in is a function of engine power and that is variable, pressurisation is controlled by adjusting the amount being let out through the Outflow Valve. This is at the back of the aircraft (hence the front to back flow) and you can often see them fully open on the ground, usually near the rear doors, slightly below.

That’s you, AC&P Qualified.
Quote "This gives pressurised, temperature controlled air that is delivered to the cabin. It then flows from floor to ceiling, front to back. Some of it is recirculated through filters to reduce the Bleed Air consumption as taking air off the engines reduces their performance. This is the bit that Tin Foil Hatters get all twitched about but the reality is that the amount recirculated is very small, the filters are very high grade and can catch even virus size particles and the amount of fresh air and tge rate at which it is replenished together with the ceiling to floor flow makes the air arguably better quality than that in an operating theatre. The flight deck has a separate supply that doesn’t include recirculated air, primarily to ensure smoke removal procedures keep us alive"

There was some reporting a few years back that BAE 146 aircraft had problems with air contamination affecting Flight Deck crew as well as cabin crew and passengers. I would guess that this problem was specific to this aircraft.
 
Quote "This gives pressurised, temperature controlled air that is delivered to the cabin. It then flows from floor to ceiling, front to back. Some of it is recirculated through filters to reduce the Bleed Air consumption as taking air off the engines reduces their performance. This is the bit that Tin Foil Hatters get all twitched about but the reality is that the amount recirculated is very small, the filters are very high grade and can catch even virus size particles and the amount of fresh air and tge rate at which it is replenished together with the ceiling to floor flow makes the air arguably better quality than that in an operating theatre. The flight deck has a separate supply that doesn’t include recirculated air, primarily to ensure smoke removal procedures keep us alive"

There was some reporting a few years back that BAE 146 aircraft had problems with air contamination affecting Flight Deck crew as well as cabin crew and passengers. I would guess that this problem was specific to this aircraft.
No. That is conflating two issues, my fault for not making it clear.

The Tin Foil Millinery advocates are claiming we are all being poisoned by everyone else’s body effusions by recirculating “pre-breathed air”. These are the same people who gladly stand in crowded lifts, bars etc.

The contaminated air issue I believe you are referring to regards air being contaminated by foreign matter entering the system. This centres on organo-phosphates which some may remember caused a furore some years ago amongst sheep farmers as sheep dip had high levels of the stuff. It’s been linked to a variety of medical issues, principally respiratory and degenerative brain diseases.

Most oils used on modern jet aircraft are synthetic and also contain organo-phosphates. The argument is that these are entering the system and there are documented cases amongst crews of medical deterioration. It’s very hard to prove because of course manufacturers and airlines have closed ranks and argue that the contamination of the individual could have been from a different source; to some extent they’re right, the stuff is everywhere.

On the other side of the argument, the Rolls Royce RB211 has been implicated citing leaking engine bearings* and the Airbus A320 family through hydraulic bay leaks running back along the airframe and entering the APU air inlet. As above, both main engines and APUs are integral supplies of air to the cabin. This is not the case in the 787 which doesn’t use bleed air.

*Main bearings obviously require serious lubrications. Many engines use something called a labyrinth seal to keep the oil in the bearing(during operation). This uses pressurised air to keep the oil in by counteracting the pressure of the oil trying to force its way out. It works very well when up and running but the problem arises when you shut down. In most cases the air pressure bleeds off faster than the oil pressure so the oil wins the battle and pools in the engine. Next time you start up the oil gets vaporised (or more accurately, becomes an aerosol) and arguably enters the air system.

@beefer will tell you all about the Gem engines on the Lynx, another RR engine. Westland then amplified the problem by mounting the engines at a (IIRC) 7 degree arse down angle. This is why Lynx always looked show room ready (at least from the engine exhaust back); they were coated in engine oil.

Edited to change oregano-phosphates to organo-phosphates. Bloody productive tits function!
 
No. That is conflating two issues, my fault for not making it clear.

The Tin Foil Millinery advocates are claiming we are all being poisoned by everyone else’s body effusions by recirculating “pre-breathed air”. These are the same people who gladly stand in crowded lifts, bars etc.

The contaminated air issue I believe you are referring to regards air being contaminated by foreign matter entering the system. This centres on organo-phosphates which some may remember caused a furore some years ago amongst sheep farmers as sheep dip had high levels of the stuff. It’s been linked to a variety of medical issues, principally respiratory and degenerative brain diseases.

Most oils used on modern jet aircraft are synthetic and also contain organo-phosphates. The argument is that these are entering the system and there are documented cases amongst crews of medical deterioration. It’s very hard to prove because of course manufacturers and airlines have closed ranks and argue that the contamination of the individual could have been from a different source; to some extent they’re right, the stuff is everywhere.

On the other side of the argument, the Rolls Royce RB211 has been implicated citing leaking engine bearings* and the Airbus A320 family through hydraulic bay leaks running back along the airframe and entering the APU air inlet. As above, both main engines and APUs are integral supplies of air to the cabin. This is not the case in the 787 which doesn’t use bleed air.

*Main bearings obviously require serious lubrications. Many engines use something called a labyrinth seal to keep the oil in the bearing(during operation). This uses pressurised air to keep the oil in by counteracting the pressure of the oil trying to force its way out. It works very well when up and running but the problem arises when you shut down. In most cases the air pressure bleeds off faster than the oil pressure so the oil wins the battle and pools in the engine. Next time you start up the oil gets vaporised (or more accurately, becomes an aerosol) and arguably enters the air system.

@beefer will tell you all about the Gem engines on the Lynx, another RR engine. Westland then amplified the problem by mounting the engines at a (IIRC) 7 degree arse down angle. This is why Lynx always looked show room ready (at least from the engine exhaust back); they were coated in engine oil.

Edited to change oregano-phosphates to organo-phosphates. Bloody productive tits function!
Ah, the RR Gem.

My understanding - looong time ago - was that the bearings at the back end of the engine were lubricated by oil held in place by bleed air so when the engine was shut down the oil simply ran down and out of the exhaust pipe. Maybe @Nimbus can add some info.

At one point we used to carry two sawn-off oil cans which we hung from the exhaust after shutdown to catch the drips. The exhaust pipe was also quite hot so it was not unusual to have smoke pouring out as well.

I once shut down at a German civvy airport and found myself surrounded by fire trucks two minutes later.
 
Ah, the RR Gem.

My understanding - looong time ago - was that the bearings at the back end of the engine were lubricated by oil held in place by bleed air so when the engine was shut down the oil simply ran down and out of the exhaust pipe. Maybe @Nimbus can add some info.

At one point we used to carry two sawn-off oil cans which we hung from the exhaust after shutdown to catch the drips. The exhaust pipe was also quite hot so it was not unusual to have smoke pouring out as well.

I once shut down at a German civvy airport and found myself surrounded by fire trucks two minutes later.
Yep, labyrinth seals.
 
Ah, the RR Gem.

My understanding - looong time ago - was that the bearings at the back end of the engine were lubricated by oil held in place by bleed air so when the engine was shut down the oil simply ran down and out of the exhaust pipe. Maybe @Nimbus can add some info.

At one point we used to carry two sawn-off oil cans which we hung from the exhaust after shutdown to catch the drips. The exhaust pipe was also quite hot so it was not unusual to have smoke pouring out as well.

I once shut down at a German civvy airport and found myself surrounded by fire trucks two minutes later.
It’s been a long time since I was lectured on ‘abra dabble’ seals… like many gas turbines, gem works with a ‘total loss’ oil system, ie you keep topping up the oil and it disappears out of the back. Depending on the state of the abradable seals, more or less oil ended up on the floor. The oil consumption is monitored by the EFD (early failure detection) cell as well as any metal particulate in the scheduled oil samples or on the magnetic plugs.
 
As I was told it - Wastelands designed the Lynx so that the engines would be horizontal when the aircraft was in the cruise (for those whose experience of aircraft is only fixed-wing, virtually all helicopters fly nose-down to one degree or another), but neglected to tell RR this. RR assumed the engines would be virtually horizontal at all stages of flight. When the aircraft is on the ground the engines sit in a tail-down attitude and the rest, as they say, is covered by the esteemed members, above.
 
I once shut down at a German civvy airport and found myself surrounded by fire trucks two minutes later.
Just remembered.

Same trip, same airfield. When we explained that the helicopter was not about to burn to the ground the fire trucks departed with much scratching of heads.

So we called for fuel. Along comes a BFO tanker and we show him where to plug in his pressure hose. We set the fuel counter in the cockpit and tell matey the fuel will stop flowing when the required amount is reached. “Ja gut” says yer man. “Ja gut” says Beefer.

So it was with much consternation when we observe a horizontal squirt of Jet A1 about 40 feet long shooting out of the pressure relief pipe. Yer man had set the delivery pressure to “Large Airliner” instead of “Shitty little helicopter”. Yer man knocked off the fuel lever and we all looked at each other in a WTF moment.



At that moment the fire trucks turned up - again...
 
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Automatic refuelling shut off systems.

Right up there with chocolate fire guards, motorcycle ash trays, Dianne Abbott and the Household Division.
 
Just remembered.

Same trip, same airfield. When we explained that the helicopter was not about to burn to the ground the fire trucks departed with much scratching of heads.

So we called for fuel. Along comes a BFO tanker and we show him where to plug in his pressure hose. We set the fuel counter in the cockpit and tell matey the fuel will stop flowing when the required amount is reached. “Ja gut” says yer man. “Ja gut” says Beefer.

So it was with much consternation when we observe a horizontal squirt of Jet A1 about 40 feet long shooting out of the pressure relief pipe. Yer man had set the delivery pressure to “Large Airliner” instead of “Shitty little helicopter”. Yer man knocked off the fuel lever and we all looked at each other in a WTF moment.



At that moment the fire trucks turned up - again...

If the setting for a twin-engined world-helicopter-speed-record-holding Lynx is “shitty little helicopter”, what on earth did they use for Scouts and Gazelles? :D
 
Just remembered.

Same trip, same airfield. When we explained that the helicopter was not about to burn to the ground the fire trucks departed with much scratching of heads.

So we called for fuel. Along comes a BFO tanker and we show him where to plug in his pressure hose. We set the fuel counter in the cockpit and tell matey the fuel will stop flowing when the required amount is reached. “Ja gut” says yer man. “Ja gut” says Beefer.

So it was with much consternation when we observe a horizontal squirt of Jet A1 about 40 feet long shooting out of the pressure relief pipe. Yer man had set the delivery pressure to “Large Airliner” instead of “Shitty little helicopter”. Yer man knocked off the fuel lever and we all looked at each other in a WTF moment.



At that moment the fire trucks turned up - again...
It was always hilarious when one of the BFO airliner tankers rocked up to refuel a Gazelle. Even hilariouser watching the operator trying to figure out how he was going to attach the pressure fuelling connector.
 

R0B

War Hero
Automatic refuelling shut off systems.

Right up there with chocolate fire guards, motorcycle ash trays, Dianne Abbott and the Household Division.

I spent a few months on POL.

When we used to fill up bowsers the fuel delivery slowed at about half full as the shut-off value was beginning to close, this could be a bit inconvenient if there was a queue of bowsers so we would often get under the tank and lean against the value to force it open which made the bowser fill-up much faster.

The skill was in listening to the sound air coming out of the top and remembering to stop leaning on the value when it started to whistle as it was nearly full. Often we would be in deep conversation when AVTUR started to run down your neck due to it now cascading down the side of the tanker.

DSC_0513.jpg
 
Fuelling Feck Ups could be a thread on their own.

1. We often have to have a fire truck on “local standby” if we are running late and need to board pax whilst still refuelling. It depends on local airport regs and as such is nothing more than a money making exercise by the airport as they charge for it. Natch. Most of the time the fire truck is crewed up by blokes in shorts and T shirts.

2. Sat on the aircraft one day, pottering on with pre flight when all of a sudden, all the ground staff start hurtling around at speeds not normally associated with ground staff (usual operating speed: 3 rpm). Turns out an engineer on the aircraft next to us had been changing a fuel pump. These are accessed via an underwing panel and are designed in such a way that as you remove the pump a seal drops down to stop fuel escaping thus allowing pumps to be changed in tanks still containing fuel.

That‘s the theory anyway.

Poor bloke was there trying to push the pump back in as literally tonnes of fuel was trying to push it back out. Guess who won. Anyone who has ever spilt a bit of diesel will know how far it spreads. Jet fuel does the same thing.

3. Command Course: Training and Testing of potential Captains. The flying phase is 12 days of 2 flights a day split into blocks of 3. Every 3rd day is a Progress Check flight. On one such day I got on the aircraft to do Gatwick-Geneva, one of the shortest runs we do, not much more than an hour. Having ordered something like 8 tonnes of fuel I was somewhat nonplussed to find we had 40 odd loaded. That meant that on arriving at GVA we’d be too heavy to land. Examiner‘s head splits in two such was his grin. As a Trainee Captain, all problems are yours.

It turns out the aircraft had tried to go to Egypt the previous day, been fuelled up, had some sort of problem, not gone, fixed and left for me. Epic. You can’t defuel it because that takes days for all sorts of reasons.

I replanned the whole flight at 15,000’, the lower you are, the more fuel you burn (some brilliant sightseeing en route) and calculated I’d need to spend x minutes in the hold at GVA with gear and flaps out to increase fuel burn and get it down to Max Landing Weight. I was spot on, to the minute.

Started the Approach, got to 3 miles out and the aircraft ahead dumped all its hydraulics on the runway so had to go around and spend an hour in the hold whilst they cleared up the mess.

I was the only aircraft with enough fuel to hang around that long. Hehehehe.

Postscript: Some idiot in Head Office sent me a letter saying well done for having the foresight to carry extra fuel. Truly, they walk among us.
 
The skill was in listening to the sound air coming out of the top
The Scout fuel tank was under the engine deck and had a flat top so as you say you had to listen to the air coming out as it’s pitch got higher as the fuel level rose. Failure to slow down the delivery resulted in a severe “splash back” covering the poor refuelled in finest kero.

So it came to pass that me and my mate “Skinny Bob” (RIP) were on a jolly down to the American sector in Germany - a visit to a PX may have been involved - when we called in to the US Army flying station at Büdingen for fuel. Along comes the tanker and this huge black guy - other colors of refuelers are available - jumps out and starts to pump fuel

Me “excuse me but as you get to the top, take it easy as the fuel will spill out”

Him “I got it”

Bob “No, seriously if you don’t slow down you’ll get a splash back”

Him “I got it”

We can now hear the fuel getting near the top and take a couple of steps back. Shortly afterwards matey boy gets drenched in fuel.


Me and Bob “you got it”
 
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This must be the most informative thread on ARRSE.
Well done.
 

Ritch

LE
A Voyager, two circling Typhoons and an NPAS plane all in the area as the G7 summit kicks off.

Screenshot_20210611-170945_Flightradar24.jpg
 
Where TF is this G7 thing, Mousehole?

All that firepower should be camped in the Thames or better yet, Islington High Street.

ETA: RAF working Friday afternoon? The shimpfing will be at fever pitch.
 
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