transaeroyyz From Canada, joined Dec 2010, 88 posts, RR: 0 Posted (3 months 4 weeks 1 day 15 hours ago) and read 4005 times:
Confirmed, birds and planes flying in V formation saves energy and fuel, brings the question, what about airlines going across the pond in formation, synchronize the auto pilots to identify each other and maintain distance, is it even close to fesable?
Speedbird741 From Portugal, joined Aug 2008, 622 posts, RR: 0 Reply 1, posted (3 months 4 weeks 1 day 14 hours ago) and read 3993 times:
There is an ongoing study of such fashion of flight being executed by the University of Cape Town, Airbus, and I believe by South African Airways as well to some extent. I believe these two links might be of interest to you and lead you onto further, more detailed information.
tdscanuck From Canada, joined Jan 2006, 11033 posts, RR: 72 Reply 2, posted (3 months 4 weeks 1 day 14 hours ago) and read 3993 times:
Quoting transaeroyyz (Thread starter): Confirmed, birds and planes flying in V formation saves energy and fuel
How was that a myth even in need of testing? It's basic aerodynamics.
Quoting transaeroyyz (Thread starter): what about airlines going across the pond in formation, synchronize the auto pilots to identify each other and maintain distance, is it even close to fesable?
The C-17 has been working on the formation flying technology required for many years. It's not really a technical hurdle, more of a certification/ATC issue.
N243NW From United States of America, joined Jul 2003, 1321 posts, RR: 28 Reply 3, posted (3 months 4 weeks 1 day 12 hours ago) and read 3934 times:
Quoting tdscanuck (Reply 2): How was that a myth even in need of testing? It's basic aerodynamics.
I think Mythbusters is running out of real "myths" to test and has recently had to resort to testing scientific facts instead, just because they sound cool.
Starlionblue From Greenland, joined Feb 2004, 15102 posts, RR: 69 Reply 4, posted (3 months 4 weeks 1 day 11 hours ago) and read 3892 times:
Quoting N243NW (Reply 3): Quoting tdscanuck (Reply 2):
How was that a myth even in need of testing? It's basic aerodynamics.
I think Mythbusters is running out of real "myths" to test and has recently had to resort to testing scientific facts instead, just because they sound cool.
Full disclosure: I am a big fan of the show. And yes, there are often basic physics being tested, such as the infamous airplane on a conveyor belt.
My comments on this kind of thing being tested:
1. I really don't think the Mythbusters themselves need any convincing if it is just "basic physics". You can often catch them playing a bit dumb, and Adam especially often has snarky comments about the whole thing ("unless we have somehow been transported to another planet, I doubt this will work." comes to mind).
2. The inquisitive general public (AKA the target audience) typically has little grasp of this kind of thing.
It's all well and good to sit here in tech_ops, but most people are both less than well educated and less than analytically minded. So let's cut the Mythbusters a bit of slack shall we?
Tact Is For People Who Aren't Witty Enough To Be Sarcastic
PapaChuck From United States of America, joined Aug 2010, 112 posts, RR: 0 Reply 5, posted (3 months 4 weeks 1 day 5 hours ago) and read 3715 times:
Mythbusters, while I love the show, is just like any other. Ratings are more important than true science. If it sounds cool and we can get more people to tune in, then let's do it!
Also, technical and ATC issues aside (which by themselves would kill the idea), would anyone really want to spend eight hours riding the wake of a 747?
"Hey center, how are you rides ahead? We're getting continuous moderate chop and some mountain wave."
"Your wingman says it's been smooth since wheels up."
tdscanuck From Canada, joined Jan 2006, 11033 posts, RR: 72 Reply 6, posted (3 months 4 weeks 1 day 3 hours ago) and read 3634 times:
Quoting PapaChuck (Reply 5): Also, technical and ATC issues aside (which by themselves would kill the idea), would anyone really want to spend eight hours riding the wake of a 747?
In order for the idea to work, you can't be inside the wake. You need to be in an area of smooth upwash, which has to be outboard of the trailing vortices. Away from the ground, the wake vortices tend to move together and stream aft and down about half a wingspan apart...if you're running into those, you're way outside the typical "V" formation.
PapaChuck From United States of America, joined Aug 2010, 112 posts, RR: 0 Reply 8, posted (3 months 4 weeks 1 day 1 hour ago) and read 3560 times:
I understand that you would need to fly outside and above the core of the vortex to see any benefit at all, but would the upward flow of air be uniform over the 200 foot wingspan of a trailing aircraft? While not technically in the wake, I find it hard to believe that it would be a perfectly smooth ride, at least requiring constant control inputs to keep the wings level.
It reminds me of yet another Mythbusters experiment where they measured fuel consumption driving in the wake of a semi. While it did indeed save gas, the closer they got, the harder it became to accurately control the throttle to keep a constant distance and thus negated some of the benefit. They closer they got, the harder they had to work.
Common sense should tell me that riding the bumper of a semi at highway speeds with my two-year-old daughter strapped in behind me is a bad idea. Scale that up to 400 people in a 747 tailgating another widebody, this should have stupid written all over it. Where does the safety and well being of paying passengers come in to play?
skysurfer From United Kingdom, joined Sep 2004, 1131 posts, RR: 17 Reply 10, posted (3 months 4 weeks 20 hours ago) and read 3387 times:
What a great example of wake turbulence it was when they lined up astern of each other and were all over the sky trying to keep it lined up!
It would've been alot better though if they'd have measured each aircraft's fuel flow flying straight and level by themselves, then tested all of the aircraft in the V formation.
Stu
In the dark you can't see ugly, but you can feel fat
N243NW From United States of America, joined Jul 2003, 1321 posts, RR: 28 Reply 11, posted (3 months 4 weeks 16 hours ago) and read 3289 times:
Quoting Starlionblue (Reply 4): It's all well and good to sit here in tech_ops, but most people are both less than well educated and less than analytically minded. So let's cut the Mythbusters a bit of slack shall we?
I agree with everything you said. I enjoy the show as well, but I just figured it was worth mentioning...
tdscanuck From Canada, joined Jan 2006, 11033 posts, RR: 72 Reply 12, posted (3 months 4 weeks 15 hours ago) and read 3279 times:
Quoting PapaChuck (Reply 8): I understand that you would need to fly outside and above the core of the vortex to see any benefit at all, but would the upward flow of air be uniform over the 200 foot wingspan of a trailing aircraft?
At the separations most studies seem to work with, it will be pretty uniform. Not 100%, of course, but not nearly as bad as you might think.
Quoting PapaChuck (Reply 8): While not technically in the wake, I find it hard to believe that it would be a perfectly smooth ride, at least requiring constant control inputs to keep the wings level.
This whole idea really only applies in cruise and pretty much guarantees that it can only be done in autopilot, at which point constant control inputs aren't an issue. Smoothness is different...bumps come from shear. The only source of shear is the trailing vortex sheet, which rolls up to form the trailing vortices. You're way outside that in normal V-formation position...you're just in the bulk updraft from the aircraft which isn't totally uniform but contains almost no shear at all.
Quoting PapaChuck (Reply 8): It reminds me of yet another Mythbusters experiment where they measured fuel consumption driving in the wake of a semi.
A semi has a square back end and throws huge alternating vertical vortices...it's pretty much the opposite of the wake off an airliner.
Quoting PapaChuck (Reply 8): Scale that up to 400 people in a 747 tailgating another widebody, this should have stupid written all over it. Where does the safety and well being of paying passengers come in to play?
This idea doesn't work by tailgating...you're not behind or beside the other aircraft. You should be able to maneuver in any direction and not hit anyone unless you change speed. Since the whole concept relies on slaved autopilots it's really not that big a deal...if the system is working, stay in formation and you're fine. If it's not, descend and you're clear.
An ILS autoland is a way harder collision problem than this is.
UAL747 From , joined Dec 1969, posts, RR: Reply 13, posted (3 months 4 weeks 12 hours ago) and read 3202 times:
In reality, the airplanes all have to take off, then line up in formation meaning others have to circle and wait or fly incredibly slow while others fly incredibly fast, then once they near an airport, they must break off and separate for landing meaning they will have to circle once they reach their destinations. Seems that all fuel savings would be lost in this process and it's not economically feasible.
Also, from how I understand this works, the planes ride on each others vortexes, on the upward movement or "side" of the vortexes. This air is extremely turbulent, so it probably wouldn't work that way either.
tdscanuck From Canada, joined Jan 2006, 11033 posts, RR: 72 Reply 14, posted (3 months 4 weeks 10 hours ago) and read 3186 times:
Quoting UAL747 (Reply 13):
In reality, the airplanes all have to take off, then line up in formation meaning others have to circle and wait or fly incredibly slow while others fly incredibly fast, then once they near an airport, they must break off and separate for landing meaning they will have to circle once they reach their destinations. Seems that all fuel savings would be lost in this process and it's not economically feasible.
You're assuming they all depart and arrive at the same airport...there's nothing wrong with, say, the DC flight to Europe picking up two or three flights of New York and Philly and one from Boston then all following the same NAT in formation until they get to Shannon or so, then breaking apart to their final destinations. If the fuel savings is bigger than the relatively small increase in route length, it works out economically.
Quoting UAL747 (Reply 13): Also, from how I understand this works, the planes ride on each others vortexes, on the upward movement or "side" of the vortexes. This air is extremely turbulent, so it probably wouldn't work that way either.
It's only extremely turbulent near the vortex core where the shear is high...that's below and about half a semi-span inside the wing tips...not where your formation mates are flying. This is no different than photo-shoot or air show formations and they don't have a turbulence problem.
Starglider From Netherlands, joined Sep 2006, 642 posts, RR: 44 Reply 15, posted (3 months 4 weeks 10 hours ago) and read 3178 times:
Quoting UAL747 (Reply 13): In reality, the airplanes all have to take off, then line up in formation meaning others have to circle and wait or fly incredibly slow while others fly incredibly fast, then once they near an airport, they must break off and separate for landing meaning they will have to circle once they reach their destinations. Seems that all fuel savings would be lost in this process and it's not economically feasible.
Then this is the time to start designing and building large seaplanes and seabases.
bellancacf From United States of America, joined May 2011, 51 posts, RR: 0 Reply 16, posted (3 months 3 weeks 6 days 14 hours ago) and read 2925 times:
I once saw a vee of cormorants pass overhead, followed by two stragglers. Straggler A was content to come in last and slotted onto the end of the near arm of the vee; wingbeats slowed by a good third. Straggler B was a more competitive sort and wanted to be near the head of the vee; when the vee passed out of sight, Straggler B was still working hard to catch the vee while flying straight up the middle --- harder than any of the other birds, in fact. Even the leader of the vee, which I found curious ... Is there any reason the lead bird/plane might find an advantage in having other birds/planes in the vortices?
Related: I once found that a hand-launched glider with squared (as in 90 degrees) wingtips and a slight sweep (15 degrees) flew __much__ farther and better than the same plane with wingtips parallel to the fuselage. Always assumed that it was because the trailing edge got out of the way of the downdraft side of the vortex as it moved forward. The planes would leave your hand, give a little shake, squat slightly, and go find a thermal. Took to writing my phone number on them.
tdscanuck From Canada, joined Jan 2006, 11033 posts, RR: 72 Reply 17, posted (3 months 3 weeks 6 days 13 hours ago) and read 2913 times:
Quoting bellancacf (Reply 16): Is there any reason the lead bird/plane might find an advantage in having other birds/planes in the vortices?
Unless you're going supersonic, the rotation extends both in front of and behind the aircraft. It's not as pronounced in front but the lead aircraft is still getting some boost from the updraft outside his trailing neighbors.
Starlionblue From Greenland, joined Feb 2004, 15102 posts, RR: 69 Reply 18, posted (3 months 3 weeks 6 days 11 hours ago) and read 2887 times:
Quoting tdscanuck (Reply 17): Quoting bellancacf (Reply 16):
Is there any reason the lead bird/plane might find an advantage in having other birds/planes in the vortices?
Unless you're going supersonic, the rotation extends both in front of and behind the aircraft. It's not as pronounced in front but the lead aircraft is still getting some boost from the updraft outside his trailing neighbors.
In the case of ducks and other formation flying birds, the lead position is traded off regularly in order to ensure one bird does not carry the whole burden.
Shouldn't be too hard to program that in I guess.
Tact Is For People Who Aren't Witty Enough To Be Sarcastic
ferpe From France, joined Nov 2010, 956 posts, RR: 41 Reply 19, posted (3 months 3 weeks 6 days 8 hours ago) and read 2846 times:
Quoting tdscanuck (Reply 14): This is no different than photo-shoot or air show formations and they don't have a turbulence problem.
Oh yes they do, once you hit the vortex sheet the movement of your aircraft is pretty hefty even for a 15t fighter. That is why flying close formation is such an art of staying outside the lead aircrafts vortex or be prepared to counter with rather big stick movements if needed. If you were to see the stick of one of the trailing aircraft on those airshow formations you would see what hard work it is, no smooth sailing, BIG corrections, they fly so close they hit vortexes all the time. Those are the most difficult places in the formation for that reason.
For normal fighter pilots you get into the same situation when you fly formation in clouds, if they are dense you have to get to about 3-5 meters from the other frame not to loose him. Then you make very sure you stay out of his vortexes and if you hit them you correct razorfast and distinct to get out of them. No way you can fly in them.
Even when changing flanks trailing about 50-100 meter you go down a lot to not hit the vortex sheet. In flight academy you deliberately go up and hit it, you get roll disturbances of 30° for a Hawk style jet.
PS the above is just a correction of the thought that airshow style formation flying is smooth sailing, for the V form to work practically you stay outside these vortex sheets as said and there is good reasons for it DS
geezer From United States of America, joined Aug 2010, 713 posts, RR: 1 Reply 20, posted (3 months 1 week 6 days 12 hours ago) and read 1972 times:
This very interesting discussion about turbulence from planes flying close together has reminded me of something I read about many years ago....................when the USAF was testing the XB-70 Valkyrie they always used at least one chase plane as an "observer"; on one fateful flight, the late Joe Walker was flying the F-104 Starfighter chase plane; something happened, and the F-104 collided with the B-70; the F-104 was lost, as was the pilot, and the XB-70 I believe ended up making a rather spectacular landing on a highway. ( There were only 2 copies of the B-70 made )
Does anyone here remember this, and if so, is it fair to speculate that wake turbulence had a hand in causing this tragedy?
It's been a long time since I read about this, but I do remember that there were many people (think "brass" ) in the USAF that were making all sorts of extremely unflattering comments about Joe Walker; ( who I believe was working for NASA, ( or possibly the old NACA ) at the time. I'm sure these comments upset more than a few people, as Joe Walker was considered to be among the top test pilots of the time.
I would love to hear some "educated" discussion about this incident.
rwessel From United States of America, joined Jan 2007, 1615 posts, RR: 2 Reply 21, posted (3 months 1 week 6 days 10 hours ago) and read 1950 times:
Quoting geezer (Reply 20): This very interesting discussion about turbulence from planes flying close together has reminded me of something I read about many years ago....................when the USAF was testing the XB-70 Valkyrie they always used at least one chase plane as an "observer"; on one fateful flight, the late Joe Walker was flying the F-104 Starfighter chase plane; something happened, and the F-104 collided with the B-70; the F-104 was lost, as was the pilot, and the XB-70 I believe ended up making a rather spectacular landing on a highway. ( There were only 2 copies of the B-70 made )
The F-104 sheared of most of both vertical stabilizers on the XB-70, and did additional damage to the wing. The XB-70 remained in level flight for a few seconds after the collision, but then rolled inverted, entered a flat spin, had additional structural failures from the aerodynamics loads (the photos show a large could of fuel venting from the ruptured left wing), and finally impacted the desert floor. White ejected, but was very badly injured, Cross did not, and died in the accident. There was no landing.
Quoting geezer (Reply 20): Does anyone here remember this, and if so, is it fair to speculate that wake turbulence had a hand in causing this tragedy?
It's been a long time since I read about this, but I do remember that there were many people (think "brass" ) in the USAF that were making all sorts of extremely unflattering comments about Joe Walker; ( who I believe was working for NASA, ( or possibly the old NACA ) at the time. I'm sure these comments upset more than a few people, as Joe Walker was considered to be among the top test pilots of the time.
I would love to hear some "educated" discussion about this incident.
While wake turbulence has been discussed, specifically the vortex off the right wingtip, the problem is that the effect is not usually severe enough to prevent the trailing aircraft from compensating, or maneuvering out of the wake, at least until you're *really* close. And on numerous prior flights chase planes had not noticed anything unusual as far as that was concerned.
While I don't think we'll ever know exactly what happened, the problem is that there were no apparent failures anywhere else. The telemetry from the XB-70 showed no abrupt motions or mechanical failures (until the collision), other pilots reported no (atmospheric) turbulence during the that time, and while it can't be ruled out, the odds of a mechanical or structural failure of the F-104 at that exact time are remote (and there was no evidence of any such in the wreckage), and the other pilots noted no unusual flying from either the XB-70 or the F-104.
So what does that leave? Walker was a highly experiences and well regarded pilot. Yet his F-104 hit the XB-70. Might he have suffered a medical problem? Hypoxia was theorized, but without evidence (and the apparently normal performance of the F-104 prior to the accident would suggest that Walker was not impaired). Perhaps distracted by something in the aircraft or outside (there was a B-58 crossing their path, although above them, just before the collision)? But would an experienced pilot let his attention drift during a close formation flight? And if he had an issue, the first thing to do would be to open the range, and *then* deal with the issue. And yet the F-104 managed a (fairly) slow drift into its lead aircraft, which is the sort of thing that happens when you get distracted.
geezer From United States of America, joined Aug 2010, 713 posts, RR: 1 Reply 22, posted (3 months 1 week 6 days ago) and read 1855 times:
Quoting rwessel (Reply 21): The F-104 sheared of most of both vertical stabilizers on the XB-70, and did additional damage to the wing. The XB-70 remained in level flight for a few seconds after the collision, but then rolled inverted, entered a flat spin, had additional structural failures from the aerodynamics loads (the photos show a large could of fuel venting from the ruptured left wing), and finally impacted the desert floor. White ejected, but was very badly injured, Cross did not, and died in the accident. There was no landing.
Thank you so much ! (Just goes to show how accurate my memory is ! ) Somewhere back in my memory, I could swear I read something about the XB-70 having some kind of emergency and ending up landing on a road.........
Inasmuch as the copy of the B-70 that I have seen many times at the Air Force Museum is still intact, I just "assumed" the other copy was the one involved in the road incident. ( Which incident, BTW, apparently involved another aircraft. )
My brother-in-law had worked in experimental engineering at Wright Field during and slightly after WW 2, and knowing a lot of people there, we used to hear quite a lot about on-going Air Force projects there. I'm thinking of taking a short trip over to Ohio to visit the AF Museum in the next few months, so I will be checking out the history of the XB-70.
If I'm not mistaken, (again, this is from memory), I think Joe Walker was also one of the pilots who was involved in the testing of the X-15; ( they certainly didn't pick any "bozo's" to fly that thing ! )
Based on what you have told us about that crash, apparently ejection seat technology back then was no where near what it is today. I know the Air Force tried a lot of seemingly "hair-brained" schemes back in the 50's, the vast majority of which ended up in complete failure. You mentioned the B-58 Hustler.............we saw a LOT of those back in the early days of that program.
OldAeroGuy From United States of America, joined Dec 2004, 3141 posts, RR: 66 Reply 23, posted (3 months 1 week 5 days 23 hours ago) and read 1825 times:
Quoting geezer (Reply 20): ....................when the USAF was testing the XB-70 Valkyrie they always used at least one chase plane as an "observer"; on one fateful flight, the late Joe Walker was flying the F-104 Starfighter chase plane;
It wasn't a test flight. There were other airplanes in the formation including an F-4, F-5, and T-38. All the airplanes were powered by GE engines and the flight was photo op for a GE advertisement.
geezer From United States of America, joined Aug 2010, 713 posts, RR: 1 Reply 24, posted (3 months 1 week 5 days 21 hours ago) and read 1800 times:
Quoting OldAeroGuy (Reply 23): It wasn't a test flight. There were other airplanes in the formation including an F-4, F-5, and T-38. All the airplanes were powered by GE engines and the flight was photo op for a GE advertisement.
wow ! Talk about timing ! You're absolutely correct OldAeroGuy..........I just this minute logged back on after spending the last hour and a half reading about the whole thing on WIKI ! ( Here's a link that explains the whole thing )
( Very good article BTW; I highly recommend it. )
The USAF summary report of the accident investigation stated that, given the position of the F-104 relative to the XB-70, the F-104 pilot would not have been able to see the XB-70's wing, except by uncomfortably looking back over his left shoulder. The report said that Walker, piloting the F-104, likely maintained his position by looking at the fuselage of the XB-70, forward of his position. The F-104 was estimated to be 70 ft (21 m) to the side of, and 10 ft (3 m) below, the fuselage of the XB-70. The report concluded that from that position, without appropriate sight cues, Walker was unable to properly perceive his motion relative to the Valkyrie, leading to his aircraft drifting into contact with the XB-70's wing. The accident investigation also pointed to the wake vortex off the XB-70's right wingtip as the reason for the F-104's sudden roll over and into the bomber.
[edit]
Well, after reading that, it looks as if Joe Walker's flying was a little "risky" after all. And to lose 2 lives and a 700 million dollar airplane, all over a "photo op"; How sad is that ?
So, the combination of being too close, unable to see the XB-70's wing, and the wake vortex from the wing, all ended up causing the tragedy. The lengthy article also mentions that the USAF also threw 3 officers "under the bus".......just HAD to have someone to blame it on.......
Charley
A home without a cat is just a house
25 rwessel: Well, there certainly were more issues in the early days, but the podded ejection systems, like the one on the XB-70, have more troubled history than
26 ferpe: Well for a wartime aircraft capable of Mach 3 there is not much alternatives, normal ejection seats will save the life of a pilot until slightly over
27 rwessel: Several A-12/SR-71 and MiG-25/31 high speed ejections had survivors. But the problem is not Mach, per se, rather dynamic pressure. In most cases thes
28 ferpe: yes, you are right, it is the dynamic pressure which is the problem, I assumed we were at the deck as the tactic for the B58, F111, B1 no longer coul
29 DocLightning: One thing I don't understand and maybe you can educate me: With the C-17, a military plane, the military can schedule all the flights to depart one a
30 jwenting: well said, Doc. Any benefit gained from flying in formation would be lost as they'd have to wait in a marshalling area for the group to assemble over
31 tdscanuck: "Exactly" is a relative term here. Airborne rendezvous isn't particularly difficult when it's planned. You've probably got a 5-10 minute "launch wind
32 rheinwaldner: If close formation flying ever would become feasible, I would re-think this proposal: Aerial Refueling For Civilian Airplanes (by Rheinwaldner May 9 2
33 ferpe: You are dead right, a modern ULH frame packs the following on it's spec flights: - 50% empty aircraft - 40% fuel - 10% payload It is a bit scary real
35 DocLightning: Still, 5-10 minute launch window is pretty narrow. Having three aircraft on short finals when the flight in question is lining up on the runway can r
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