I don't know for German planes. I did only read flight report for French and British planes, and talked directly with one test pilot of the BrXIV replica (who also piloted SPAD and Nieuports).

What is a BrXIV?

Bréguet 14 i guess (?)

Greetings,
Catfish

Yep

Back in the day, the rudder was the primary turning surface. If you read first hand accounts, the pilots refer to 'kicking the rudder' to turn and I have seen a WWI era film of a Nieport 11 or 17 begin its turn with the rudder and use the ailerons to trim the turn. It was not until the Fokker cantilever wing were the ailerons really effective. And it was really the D7 that probably really worked well. ( I have a theory that the Fokker D7 is where aeroplanes became aircraft.)

Javier Arango had an article in WWI Aero some 10 years back comparing two D7's they have in California. One is a Gypsy powered (230 hp - 6ft prop) from the film The Blue Max and the other is a reproduction with an actual 180hp Mercedes DIIIa (180hp (or German ps) and turning the 280 cm or 9ft 4in prop.) The large propwash of the original engine put out as much if not more thrust than the more powerful, higher reving Gypsy and did so with better airflow over the air frame and control surfaces.

Javier mentions that the small ailerons on the D7 were more effective than the larger quad ailerons on his SE5s. I think this may be due to the thick foil, flat bottom wing which is where Fokker took a big leap forward using the Goettingen airfoil. The University of Goettingen possessed the best wind tunnel and research team at the time and many of these people came to the US after the war to greatly improve NACA here in the US during the 1920's.

I have digressed. Key Points:

1. Be careful of the reports from replica flyers, if the aircraft do not have the correct power plants and propellers. The only verifiable reference should be those who have been fortunate to have reproduction (or original aircraft).

2. Try fighting your insticts and try a rudder first turn and use the ailerons to trim the turn. Banking turns were not as common in WWI.

Unfortunately, for Breguet XIV, there are only flying replicas, no original ones in flying condition.
... but for others, like Nieuports and SPAD, there are restored originals in flying conditions... you can read this post, especially the 8th paragraph for the aileron stiffness.

Great read read there Rama.

There are a couple things I would like to point out about that article.
When they are talking about how tail heavy it is while moving it around on the ground, they are referring to how much weight is on the tail skid, because the main landing gear are so far forward of CG.
When they are talking about how difficult it is to handle on take off roll, that again goes back to the landing gear being far forward of CG. The farther forward of CG the landing gear is, the worse it handles on the ground. The closer to CG, the better it handles, but tips over easier.

Notice how sensitive they said elevator was, along with that you had to hold forward pressure nearly the whole time.

He mentioned how stiff the ailerons were, he thought that something was stuck or binding. I have flown a plane with a stuck pulley in the rudder control. It made it near impossible to fly a coordinated turn. You could be flying along at 140kts, kick in some rudder, and let off and it would just stay in and not return to center. Every rudder input had to be manually countered to be recentered. Took quite a bit of force too.

Another thing to watch out for on replicas is not only the power plant, but the airfoils. A small change there can make a huge difference. There are so many minor things that can be changed on a replica to enhance flying qualities that most people would never notice.

WF2,
GP can be a factor depending on the yaw rate and angle of bank. With rotaries, it can almost be guaranteed to be a factor. Consider the effect it has on the ease of turning right vs. left. I never explicitly mentioned torque so I'm not sure why you reply to me saying it won't be a factor?

And torque won't (usually) be a (significant) factor only if we limit the discussion to engine torque, as generating/countering torque is really the main reason for having ailerons, elevators and rudder in the first place...

(Anyone else competing for the Messerschmidt (a k a besserwisser) award?)

Differential ailerons are not the end-all, be all to induced yaw. In fact, there still induced yaw even with differential ailerons. It's just reduced. Hop in a Twin Astir (with differential ailerons) and you'll see. Frise ailerons do get closer if done right, or so I'm told (no personal experience).

Not that it matters in most (powered) aircraft except for in the slow-speed regime.

RocketDog,
you are correct in that the CoG position matters squat diddley for the yaw input required in a coordinated turn. The CoG only matters if there's acceleration in the plane concerned, and in a steady coordinated turn there's no acceleration in the aircraft yaw (xy) plane.

Rotary aicraft:

S-S DI, S-S DIII, S-S DIV. No gyroscopic effect of any significance at all.

It is normal for conventional rotaries to have roughly double the gyroscopic moment that an inline of the same power has, as the engine and propeller have similar MOI. A more powerful inline will be driving a larger and heavier propeller in many types, and these will close the gap down somewhat.

A rotary powered aircraft typically has a lower mass, and lower power, so the same forces acting on it will generate a larger acceleration, but this is only a relatively small difference in most cases...

It seems overly simplistic to define rotaries as susceptible to gyro effects and neglect them from inlines, the individual types have their own combinations of rotating masses and there is considerable opportunity for overlap between the two types of engine in this respect over the course of the war.

Hello,

just to ask again, here is a photo of an Otto/Ago/Pfalz biplane - so how are those ailerons used ?



Are they uncoupled ? Or upheld in flight by the wind pressure - but how would you manoeuver with that ? I have seen this on several other planes of the time.

Thanks and greetings,
Catfish