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Aircraft to fly in formation 1.8 nm apart to save fuel like geese do

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Aircraft to fly in formation 1.8 nm apart to save fuel like geese do

Old 19th Nov 2019, 15:17
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Aircraft to fly in formation 1.8 nm apart to save fuel like geese do

https://www.telegraph.co.uk/news/sci...save-fuel.html
Is this mad, or what ? Never mind the obvious, what about TCAS for a start?

Last edited by fantom; 19th Nov 2019 at 15:28.
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Old 19th Nov 2019, 15:39
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what about TCAS for a start?
Geese normally have TAs disabled, so not an issue.
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Old 19th Nov 2019, 15:47
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I have seen geese myself meany times and assumed that there was an efficiency gain.

Turns out that 12% fuel saving has been achieved in tests with A380s. I assume that is for the following aircraft.

https://en.wikipedia.org/wiki/Formation_flying
"After A380s tests showing 12% savings, it launched its 'fello'fly' project in November 2019 for test flights in 2020 with two A350s, before transatlantic flight trials with airlines in 2021."

"Certification for shorter separation is enabled by ADS-B in oceanic airspace, and the only modification required would be flight control systems software. ... Commercial operations could begin in 2025"

Decent looking article here - https://aviationweek.com/dubai-air-s...lying-together
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Old 19th Nov 2019, 15:58
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Will it be mandatory for the following pilots to "honk" to encourage the lead aircraft?
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Old 19th Nov 2019, 15:59
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Thread title says aircraft flying 1.8nm apart. Seemed too far to make a difference. Telegraph article says 55 feet apart. Seems too close for comfort!
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Old 19th Nov 2019, 16:09
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Originally Posted by DroneDog View Post
Will it be mandatory for the following pilots to "honk" to encourage the lead aircraft?
Only when stacked.

Jokes aside, it seems a rather impressive saving just by flying closer and modifying the software.

Airbus estimates that the following aircraft can save 5-10% of fuel by flying 1.5-2 nm behind the preceding one. “This is not at all about formation flying,” Bour-Schaeffer stressed. “[The concept] has huge potential and is a very tangible solution. The air is quite smooth and therefore it is practical. There is no impact on passenger comfort.”
From the Aviation Week link.
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Old 19th Nov 2019, 16:35
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Is this mad, or what ? Never mind the obvious, what about TCAS for a start?
Not mad, a quite old idea in fact possibly reactivated today due greater automation of flight controls .
The military used this phenomenon already in WW1.
TCAS is not an issue , RAs will only be initiated if tacks converge, not parallel. System only works with RAs coupled to FD which is already the case on the A380/350.
For ATC, also not an issue as they will it will be considered a formation flight ,which means separation is the responsibility of the crews , not ATC..
Smooth air is a prerequisite of course, and how to predict that with accuracy over the oceans is THE question for me.
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Old 19th Nov 2019, 16:59
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Our cheap flights will get cheaper they just slot in behind someone else :-)
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Old 19th Nov 2019, 17:37
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Gatwick doesn't need to move its spare runway 10m to the north, then.

ATC should change - speedbird 123, easyjet 456 and ryanair 789 you are all cleared to Malaga......
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Old 19th Nov 2019, 18:09
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Stick to the aerodynamics of planes with fixed wings in arguments. Likening any effects to geese formation flying is an aberration and a presumption.

I had always thought that geese formations were to prevent the constant leaking of spent fuel from the lead geese to get in the eyes of the trailing ones. The geese are dependent on their line of sight to avoid wing tip to wing tip affects, hence the V
.
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Old 19th Nov 2019, 18:26
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So how will they get into formation in the first place without some burning lots of fuel orbiting ?
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Old 19th Nov 2019, 19:04
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Well, that's 60 years of Radar separation standards going out of the window. Makes you wonder why we bothered to impose 3 or 5nm. Still, it is good to know that cherished, & strictly applied, separation standards were all a complete waste of time. All those airmisses/airproxes which SRG wasted their time investigating. If only they had realised that those sort of standards could have been dismissed so easily. Glad I am out of it.
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Old 19th Nov 2019, 19:09
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2002...

Well, it's 17 1/2 years since that article was published and it still hasn't happened, so I shouldn't get to excited by it!
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Old 19th Nov 2019, 20:20
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Originally Posted by TheFiddler View Post
Well, it's 17 1/2 years since that article was published and it still hasn't happened, so I shouldn't get to excited by it!
lol yes...

Aircraft that mimic geese can save fuel

By Roger Highfield, Science Editor

12:01AM GMT 18 Jan 2002
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Old 19th Nov 2019, 20:42
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The Yanks tested that with their C17's and found it was about 1000m away to hit the perfect spot:

According to the data generated by this month's flight and by earlier tests over Edwards, the ideal position for a drafting airplane is 3000 feet to the port side of the leading airplane. If there were a second drafting airplane, its ideal placement would be on the starboard side, about 6000 feet from the lead. This is pretty close to the tactical formations that large Air Force planes fly already, Erbschloe says, but this research will let the Air Force fine-tune the position of its planes to make sure they're riding the updrafts, not the downdrafts.
Source article
And another article from Aviation Week about it
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Old 19th Nov 2019, 21:05
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Scoff as you will but this has been seriously investigated by Airbus for some time to overcome the obvious issues raised above of TCAS etc. Autopilot ranging is pretty straight forward technology. If they can measure sub millimetre distances between two satellites to infer gravitational anomalies in the earth's surface, keeping two aircraft 3000m apart aint hard.

The bigger commercial issues will be getting the aircraft to depart simultaneously to formate (and not wasting time loitering for the other aircraft to join) and sorting out who gets the credits in a multi company formate. As a leader do you get X nm of leading credits that you can spend in tow with another aircraft from any company...?

Clearly the savings are greater over longer routes. Two aircraft ex LHR to MEL and SYD could stay in formation for say 18 hours then split at the last 45 mins. Similarly in reverse to European destinations. 15% fuel savings are huge, equivalent to NEO engines once more. That's a lot of pax that equals $$$$.
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Old 19th Nov 2019, 21:10
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> Turns out that 12% fuel saving has been achieved in tests with A380s. I assume that is for the following aircraft.

Analysis of drafting between bicycles shows that there is also a small advantage to the leading vehicle. Its because the partial vacuum behind the leader is partly filled in by the following vehicle.
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Old 19th Nov 2019, 21:10
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And on arrival, number 2 plane then has to use up fuel orbiting while waiting for the lead goose's wake turbulence to go away, and leave space on the runway/taxiway to move around.
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Old 19th Nov 2019, 21:10
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Weather avoidance would be interesting.
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Old 19th Nov 2019, 23:04
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Just imagine the organisation and logistical problems it would ttake to get just two long-haul airliners to do this,not to mention inter-company rivalries.
But to get a group of them?
What routes are dense enough to do this?
It'd take hours to get the formation together!
And the press hysteria about collision risk?

I checked the date, it's nowhere near April. What's going on? Something brought on by all those mushrooms this fall?
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