Fokker E Series Flying tail

[leo]

What were the advantages and disadvantages of the "flying tail" set up of the the Fokker E series. I notice that some modern planes have adopted at least the elevator configuration.

[Lufbery]

What were the advantages and disadvantages of the "flying tail" set up of the the Fokker E series. I notice that some modern planes have adopted at least the elevator configuration.

Hi Leo,

From what I understand, there is no advantage to the flying rudder that was a feature of the Eindecker and Nieuport (and other) planes. The Dawn Patrol is a bunch of guys who've built Nieuport 11 replicas, and their planes have a flying rudder. Here's what Dick Starks, one of the Dawn Patrol guys, says about it on their web site:

It's simple... The Nieuport DOES NOT HAVE A BUILT-IN VERTICAL FIN FOR INHERENT DIRECTIONAL STABILITY. All its got is a full flying rudder which, since it's not fixed and just kinda floats in place, gives you no built-in directional stability at all. What do that mean? It means that if you relax pressure on the rudder bar while flying, the plane can go into a skid or slip without you knowing it. In fact, torque will automagically do it for you if you're not on the bar and ON THE BALL (so to speak.) We all swear that we've been able to hear that "click" when we really get outta whack in a turn and bury the ball on one side or the other of the tube. If you don't pay CONSTANT ATTENTION to that little booger... It'll quickly and without warning, sneak up and bite you right in the ass.

Mark Pierce does a heck of a demo in his air show act showing how the Nieuport can almost be flown sideways with very little rudder input... Or, another way of putting it would be to say.. With very little pilot attention to the ball. We call it the "Pierce Horizontal Knife Edge." While he's doing it on purpose, a little inattention on your part can have it happen to you NOT ON PURPOSE and at a low altitude at low air speed... You ain't gonna like the outcome!! What happens is that as the plane gets more and more screwed up, you start to feed in aileron to try and keep things "feeling right." Then you suddenly end up with a cross-control stall/spin and THAT'S A REAL BAD THING. (I've done this I might add, in my C-120, on purpose, with my instructor on board, at altitude, and when it finally happens, it's a real shorts-staining shocker.)

Gene DeMarco (sp?) one of the pilots at Rhinebeck wrote an article for "Flight Journal" on flying their Nieport 11 and said much the same thing. An article from NASA, called "Quest for Performance: The Evolution of Modern Aircraft" (available on-line: http://www.hq.nasa.gov/office/pao/History/...P-468/cover.htm) has the following to say about the Eindecker:

The control system employed on the Eindeckers was archaic even by 1914 standards. Lateral control was achieved by wing warping in a manner similar to that employed by the Wright brothers in 1903, and the vertical and horizontal tail units consisted of one-piece free-floating surfaces. The stability and control characteristics of the aircraft were, of course, related to the floating angles of these surfaces as the angles of attack and sideslip of the aircraft varied. The characteristics of the aircraft and the effectiveness of the control system can be judged by the comments of a modern pilot who has flown a replica of the E-III. The late Frank Tallman in his book Flying the Old Planes (ref. 110) says ". . . the major flight characteristic ever present is the feeling that if you took your hands off the stick or your feet off of the rudders, the Eindecker would turn itself inside out or literally swap ends." He also indicates that the all-moving surfaces continually hunted back and forth with an attendant feedback into the pilot's hands and feet. These characteristics describe an aircraft that by modern standards would be considered unpleasant to fly, would be unlicensable, and certainly would inspire little confidence in the mind of the pilot.

That's why the part that sticks up and the rudder attaches to is called the vertical stabilizer. It, and the horizontal stabilizer serve to help keep the airplane moving in a straight line. Modern jet fighters feature an all-moving horizontal tail (elevator), but from what I can tell, the F-105 was the first American fighter with that feature. I'm not sure exactly why modern jets have this feature, but I know that it has something to do with the high speeds the jets reach. Furthermore, on the F-111 and the F-14 at least (and maybe other planes), the two horizontal tails can be deflected at different angles to help with roll control.

Regards,

[Droops]

The flying tail should give a pilot a more nimble aircraft. I've seen a lot about a Dr1 and a 'flat turn' and believe that any plane with a flying tail would be able to do the same.

Others here that fly should be able to tell you more, or correct me if I'm wrong.

VBR,

John

Hi

"Flying tails" is a complex subject. I will try to simpify.

The simple version is that a Flying tail is limited by the critical angle of attack of the airfoil, the WW1 stuff usually stalling at 10-15 degrees. Thus, a flying tail is more likely to depart controlled flight in a maneuver AND is a lot fussier in ordinary flight with no Stabilizing surface.
A fin and Stab makes the aircraft easier to fly straight and level AND, the stall characteristics of the surface are more predictable, as, effectively, the airfoil shape chages and improves the airflow AND AOA of the surface.
The F86 E went to a flying stab because at high mach numbers, the center of pressure starts shifting aft. On the standard 86 tail, that would shift back to the Hinge on the stab producing NO control. This had been experienced earlier on the P38(and in German experience with the Bf109) but not recognized for what it was.

R

[Lufbery]

The simple version is that a Flying tail is limited by the critical angle of attack of the airfoil, the WW1 stuff usually stalling at 10-15 degrees.*Thus, a flying tail is more likely to depart controlled flight in a maneuver AND is a lot fussier in ordinary flight with no Stabilizing surface.

A fin and Stab makes the aircraft easier to fly straight and level *AND, the stall characteristics of the surface are more predictable, as, effectively, the airfoil shape chages and improves the airflow *AND AOA of the surface.

Is there any advantage in maneuverability when a plane has a flying rudder as Droops has suggested above? My guess is that there isn't an advantage -- especially if the plane is more likely to depart controlled flight during maneuvers compared to a plane with stabilizers.

Regards,

The young Cecil Lewis flew a Morane-Saulnier Type LA monoplane during the Somme campaign of 1916, and described it as the only aeroplane he ever flew that he was convinced was out to kill him.

The combination of ineffective lateral control - "useless ailerons" - and an elevator "like a gold balance" was hard to master. The aircraft "had no natural stability at all." OK, the dear ol' B.E.2c had the opposite problem, in combat at least, but poor flight characteristics - the Parasol "without engine, dropped like a stone" - were greater killers of RFC aircrew than the enemy ever were.

Methinks the flyers of the earlier wing-warping M-Ss and Fokkers must've found life even harder; imagine the total lack of control harmonisation of a control system which required a fairly hefty sideways force for lateral control while simultaneously demanding the most delicate touch fore-and-aft to control pitch.

Modern aircraft employing 'all-flying' control surfaces usually have devices to aid pilot control: spring tabs, computers, etc. The early ones had only 'control-by-wire' rather than 'fly-by-wire'; very hard on the pilot. One of the main reasons for the protracted development of the Harrier jump-jet was the need to design a control system that didn't require the pilot to have more arms than Shiva and two brains to aim the thing where he wanted to go.

But human ingenuity and skill knows no bounds, eh? Young Cecil survived to become a very old Cecil . . .

Cheers!

(8:¬)}

Simba.

I have absolutely no references to back up my theory, just gut instinct. But it seems to me that R. Saulnier used the "flying tail" in his designs (later copied by Fokker) for the simple reason that it was easier. No elevator hinges to worry about, no complex structure. Just make the whole thing move. Plus, that way you can get away with a smaller empennage.

The surprising thing to me is that Morane-Saulnier doesn't seem to have learned from experience. Fokker dropped the flying tail fast enough, but MS designs continued to have inadequate rear control surfaces into 1918...

Hi
Asked: is there an advantage to a flying rudder?
No
One of the things you have to worry about is where the center of pressure is for each axis of flight. Something in common experience is an arrow, the feathers at the rear move the center of pressure back, makes it more stable, this is why they arent at the front!
Anyway, most rudders in WW1 act like Flat plates, which have poor lift/drag characteristics at any angle of attack(which, by making lift is how they WORK!), and have stall develop at very low AOA which means the thing will, at best Snake and Shake with moderate input. A fin and rudder set up just does everything better.
In this period, there was a lot of "cut and try" going on. And a number of practices, particularly airfoils, were being used ignoring tests because it was the way the Wrights had done things, and the wrights flew first!
I am not saying anyone was being stupid. People do these things. Still Do(look at the Phantom!)

Rocky

[leo]

Fokker continued with the Flying rudder through the DVI.
I wonder what kept him at it for so long, given the disadvantages you guys presented?

[Lufbery]

Fokker continued with the Flying rudder through the DVI.
I wonder what kept him at it for so long, given the disadvantages you guys presented?

I don't know, but the disadvantages are pretty real. Maybe it's just the fact that the tail is only part of the overall design of the aircraft and Fokker was focusing more on things like airfoil design.

Regards,