DARPA to try out goose v-formation trick with jets Geese don't fly in V formation just for fun: it makes long flights a lot easier for the following birds. Pentagon scientists are now looking to exploit this effect to save fuel in military aircraft. The US military research effort is called the "Formation Flight For Aerodynamic Benefit", and it builds on previous work by NASA …
One of the biggest problems with long-range flight is formation holding - the closer the formation, the tougher the demands it makes on concentration, especially during course changes. This looks like it requires pretty close formation keeping, probably better than can be delivered by autopilots, so the saving in fuel could be negated by the cost in additional rest time required by the crews after the flight, or - worse still - an increase in formation collissions.
A traffic cop once told me that road rage is a self-fueling cycle. The bad driver tailgates, the added concentration and stress of driving too close (effectively close formation) fuels his irritation with the driver ahead, which makes him more impatient and liable to drive even closer, which requires even more concetration and stress to avoid a collission. It can sometimes lead to the tailgater physically barging the driver ahead off the road! Now, air force pilots aren't really the same mentallity as many bad drivers, but the stress of keeping close formations will increase their tiredness unless DARPA can also develop much better autopilots with a pre-configured "goose" mode (no jokes about Navy pilots liking to get close behind their wingmen needed!), this idea could save money on fuel but reduce crew availability times.
...was originally used by the Luftwaffe, who called it the schwarme, and its purpose was to allow the pilots to maintain a good watch around the formation without a high risk of collision. The RAF adopted it in 1941 or so, before this they were using the V-shaped "vic" formation, this was very inflexible and tied the two trailing aircraft to the leader tightly with all the concentration problems and collision risks that entailed.
I'll get my coat now....
I'm sure the Formula 1 Grand Prix teams have dome masses of research on this subject. I know a car is not a plane but aerodynamics are fundamental.
I always thought, maybe wrongly, that the follower who gained the advantage of the pre-broken air also added drag to the leader, so in effect the leader drags the follower along with a consequent loss of performance to the leader.
The finger four was invented by the Condor Legion in Spain, I believe by Werner Molders. It requires vertical as well as horizontal separation so the aircraft can cover each other with maximum flexibility.
This is more like the tight vic formations the RAF used at the start of the second world war that proved to be useless in combat. I can't imagine a case where this would be used in combat, so I imagine they're speaking about ferrying or transiting across friendly territory en route to the target.
IIRC the RAF nicked this formation from the Luftwaffe.
During WW1 the RFC used close formation flights of three in V formation. These were in close enough formation that the workload from holding position must have reduced their ability to spot the opposition.
The Finger Four formation was rather more spread out, so any effect on flight efficiency is doubtful. It is best understood as two combat pairs in loose formation. Each wingman supported his leader and both pairs could support each other. The benefits are that each pilot only has to keep station on one other plane, so has more time for lookout and, in addition the wider spacing further reduces the station keeping workload.
>> but the stress of keeping close formations will increase their tiredness unless DARPA can also develop much better autopilots with a pre-configured "goose" mode
Welcome to the 21st century. We have cybernetics that can do things that a pilot would be unable to. Actually that was the case in the 20th century already.
Now we just need to integrate that dog into the Hornet's cockpit to keep the flyboy's fingers from the controls.
I think you're right. If anyone can sort out the method, I'm sure airlines across the world will be interested in reducing drag by 20%. That presumably translates more or less directly into a 20% reduction in fuel costs (and CO2 emissions, for those who are counting)?
I think DARPA are going downhill. First they want a functional GPS alternative. Now they want to save the planet.
Although one might think aero is aero, there is a dramatic difference in the flow at the sort of speeds these planes cruise at vs. a F1 car. Look up Reynold Number, maybe even on Wikipedia.
It may be apocryphal, but there is a story of an F1 aero guy talking to a plane aero guy to get some tips. The plane aero guy was rather dismissive as they don't deal with speed's that low....
The Finger Four is not a close formation, it is known as a battle formation. The idea is you fly far enough apart (up to 200 yards between aircraft in 1940) that you can concentrate on searching the surrounding sky, including your wingman's blind spot, and still turn tightly enough to make a head-on attack on someone attacking your wingman from his six. It is far too far apart to get any benefit from another aircraft's disturbed airflow. To imagine the relative positions you simply need to hold out a hand with the fingers spread, ignoring the thumb, then imagine a plane at each fingertip with the leader as the longest finger.
It was not invented by Werner Molders, it was first used by the French in the Great War as a variation on line abreast. Werner Molders is thought to have simply rehashed an idea recorded by Boelke in his memoirs, all he did was re-introduce it to the Luftwaffe. They were taking a kicking in Spain in as they were flying neat vics against the Communists, who flew in loose formations. There are pictures of the Italian pilots in Spain in 1936 flying finger four long before Molder's arrival.
Flying in line abreast allowed all the aircraft in a small group to attack together and was a common concept amongst the many cavalry officers that joined the early air forces in WW1. However, line abreast made it difficult for the other pilots to see the leader, so a natural adaption was to have the leader fly ahead and the other planes slightly staggered to either side. The RFC didn't take much to it, but did often fly in pairs in a six-plane vic from late 1916 onwards.
The RAF used the three-plane vic formation for fighters prior to WW2, despite knowing all about line abreast and finger four, because they concentrated on training their fighter pilots for bomber interceptions. The tight vic allowed a group of three planes to penetrate cloud (very common over the UK) with a good chance of staying in visual contact. It required considerable formation flying skill and was tactically poor as the pilot on the inside of a turn had to throttle back to hold position whilst the one on the outside had to accellerate. This meant the number 2 and 3 pilots usually used more fuel than the vic leader. It was easy to teach and looked smart, and meant three planes together could attack the same bomber and hack it down, but both outside pilots spent most of their time looking at their leader rather than searching the sky. The finger four was much superior but resisted by some RAF brass even after 1941!
In the '20s, when the RAF was deciding on tactics, nobody predicted the RAF fighters would be going up against escorted bombers as they had to in the Battle of Britain, so training for dogfights and shooting at anything other than fat bombers lumbering along in a straight line was neglected. Pretty soon into the Battle, the RAF began to tinker with formations to try and find a better solution (for example, Bob Tuck was using widely-spaced pairs over Dunkirk prior to the true BoB), leading through the dire weaver system to a gradual acceptance of the old and forgotten finger four formation.
/plane geek mode off, default silicon geek mode back on.
Actually, in at least some cases, the lead car is able to go faster.
The most obvious example is in NASCAR, where they are able to maintain extremely close spacings, so that turbulence behind the lead car is dramatically reduced. Sometimes this can also cause a loss of downforce, making it look like the lead car was hit by the second car, even though no contact occurred.
I can't say that it translates directly to this situation, but the phenomenon of drafting typically benefits both vehicles/animals/whatever. I remember reading a story years ago regarding drafting on bicycles, and while the trailing riders achieved much higher savings (something like 20% or more?) the lead rider also benefited (less than 10% IIRC).
The quick and dirty explanation is that a good portion of the drag is due directly to flow separation _behind_ you. Having the second rider there allows the air to flow better around the both of you, only separating entirely once it passes the last rider.
Of course, the major source of the drag is pressure drag (the effective headwind) which is why the lead rider doesn't benefit as much.
In short, it's not a zero-sum game.
The Royal Air Force has done many things but something else we did correctly was formation flying. It was noticed that when transferring Sabres between America, Canada and the U.K. the flight duration was too little to do it direct, but we did it.
The leg from Iceland terminated in this country at Kinloss on the coast of the Moray Firth, Sometimes the aircraft would "flame out" on the runway but they landed in complete safety. Now we know why, or did the powers that be have a direct line to the almighty? Subsequent discoveries (?) by America are things which were known and used by us so to claim a discovery they should read up on history and claim it as original thought, as they frequently do is misleading, not to say totally incorrect.
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2024
