Biplane Terminology

[Oberst Hajj]

The following is taken from Quest for Performance: The Evolution of Modern Aircraft, written by Laurence K. Loftin, Jr. I thought it might be of interest to some of you.

The terminology used to describe the major features of a typical double-bay biplane of the World War I time period is illustrated in figure D.1. The number and arrangement of struts and wires employed in biplane design have varied greatly over the years; however, the terms indicated in the figure have survived and are still in use today in any discussion of modern-day sport or agricultural biplanes. A single-bay biplane, in contrast to the two-bay arrangement shown in figure D.1, has only one set of interplane struts between the wings on either side of the fuselage, and a triple-bay design has three sets of such struts on either side of the fuselage. In contrast to the incidence wires shown in the figure, many biplane designs have utilized a single strut, in an "N" arrangement, connecting the front and rear interplane struts (see the Travelair 4000 in figure 4.5, for example). This configuration eases the task of rigging, or aligning, the wings in the correct relation to each other and the fuselage. The proper rigging of wire-braced aircraft once formed an extremely important part of any aircraft erection, maintenance, or repair operation. Today, the experienced rigger is almost extinct, and the art is all but lost except for a few dedicated enthusiasts engaged in the restoration of antique aircraft or in the building and flying of sport biplanes. Decalage is a term, not illustrated in the figure, that is sometimes encountered in discussions of biplanes. It refers to the difference in angle of incidence at which the upper and lower wings are mounted on the aircraft.

http://www.wingsofwar.org/forums/picture.php?albumid=18&pictureid=553

http://www.wingsofwar.org/forums/picture.php?albumid=18&pictureid=554


1. Interplane struts.
2. Cabane or center-section struts.
3. Flying wires.
4. Landing wires.
5. Incidence or stagger wires.
6. Drag wires.
7. Center-section cross bracing.
8. Aileron control wires.
9. Elevator control wires.
10. Control horn.

[Tonx]

Finding this a very interesting read but it begs the question: How many of these terms apply to the Bi-Planes of World War 2?

Since this thread was started ARES have released both the Gloster Gladiator / Sea Gladiator and the Fiat CR.42 Falco as Official :minis: for Wings of Glory WW2 / WGS. My WGS playing career began with the Gloster Gladiator ... Most amazing manoeuverability compared with faster and later WW2 aircraft types although the one thing the Gladiator does lack is firepower.

[flash]

Finding this a very interesting read but it begs the question: How many of these terms apply to the Bi-Planes of World War 2?...

Most if not all of them Barney - as you can see the Gladiator is well wired !

http://www.vintagewings.ca/Portals/0/Vintage_Stories/News%20Stories%20I/The%20Last%20of%20the%20Biplane%20Fighters/Gregor33.jpg

[Jager]

I just did a quick sweep on Wiki of the WW2 biplanes I could remember, and all had wire bracing. This is interesting since one of the big innovations of the Fokker D.VII was the lack of wire bracing.
Karl

[Flying Officer Kyte]

Yes, I wonder what caused this retrogressive step Karl?
Rob.

[matt56]

I wonder if more powerful engines allowing faster dives/climbs/maneuvers in general necessitated reinforcing with wire rigging?

All the best,
Matt

[Tonx]

I wonder if more powerful engines allowing faster dives/climbs/maneuvers in general necessitated reinforcing with wire rigging?

It has got to be either this or for other structural engineering issues IMHO. Though I can see why the Fokker D.VII was so innovative in eliminating both structural wiring and thus additional parasite drag generation when in flight ...

However innovation can come with a price if one's luck is pushed with it in particular: Biplanes aeronautically behave very differently from monoplanes. Particularly when at high speed and even more particularly when in a dive. Because of this the impediment posed by the presence of structural wiring where parasite drag generation can actually slow the aircraft down in a useful manner on it's own accord would come in handy. To bring the aircraft back to an airspeed where the flight controls regain their effectiveness and to a fuller extent without structural damage occurring. Particularly applicable to high-speed dives where over a prolongued period of time the aircraft in losing height travels from a lower air density higher up to a higher air density close to the ground. In aviation there have been as many structural break up accidents attributed to air density (including ground effect) as airflow effects.

Although there was not a biplane involved the death of John Derry at the Farnborough Air Show in 1952 is one of the most famous air density related structural break up accidents. He pushed his luck with the prototype de Havilland Sea Vixen ... But on Day 6 of that particular Farnborough Air Show (the Saturday so it was a Public Flying Display Day) he pushed his luck that little bit too far and the results were fatal.

[Jager]

I do remember that there was some concern with wing flutter with the later Fokker products (Dr.I and D.VII). Indeed, Fokker insisted that the Dr.I could be flown without the major wing struts, but the High command refused to consider it.
I looked through Kenneth Munson's book on interwar fighters, and almost all had bracing wires; those that didn't (largely US) had extra struts. So there must be something to it.
Even modern stunt biplanes have bracing wires, so......
Karl

[Tonx]

Even modern stunt biplanes have bracing wires, so.....

Just mentioned this discussion to a friend of mine whose a flight instructor. The wiring incorporated into the design of the Pitts Special stunt biplane has additional functionality so she says for dispersing static electricity around the airframe. This is another thing which is generated in flight. Never thought of that purpose ...

[Jager]

Just mentioned this discussion to a friend of mine whose a flight instructor. The wiring incorporated into the design of the Pitts Special stunt biplane has additional functionality so she says for dispersing static electricity around the airframe. This is another thing which is generated in flight. Never thought of that purpose ...

Interesting..........