science

Outboard tail

Outboard tail is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Outboard tail rather than just read about it. In short: An outboard tail is a type of aircraft tail or empennage which is split in two, with each half mounted on a short boom just behind and outboard of each wing tip. It comprises outboard horizontal stabilizers (OHS) and may or may not include additional boom-mounted vertical stabilizers (fins).

Key takeaways

Outboard tail belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Outboard tail to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Outboard tail from memory before moving on to harder problems.

Reference excerpt

An outboard tail is a type of aircraft tail or empennage which is split in two, with each half mounted on a short boom just behind and outboard of each wing tip. It comprises outboard horizontal stabilizers (OHS) and may or may not include additional boom-mounted vertical stabilizers (fins). OHS designs are sometimes described as a form of tailless aircraft. The outboard tail surfaces are positioned so that they interact constructively with the wingtip vortices to significantly reduce drag, without causing undue structural or handling difficulties.

Characteristics

An outboard tail is located outboard of the main wing tips. Although sometimes described as tailless, the outboard tail configuration differs from a tailless wing in that the horizontal stabilizer is discontinuous from the main wing surface, typically being set further back and requiring a short boom to support it. If the wing is swept, then the boom can be very short and the front of the tail may overlap the rear of the wing. The tail comprises outboard horizontal stabilizers (OHS) and may or may not include additional boom-mounted vertical stabilizers (fins). A normal wing tip creates a significant trailing vortex, due to an upwash of air spilling up round it from underneath and then moving inwards towards the low pressure region above the wing surface. These vortices can carry away significant amounts of energy, thus increasing drag. In the outboard tail configuration, the tail surfaces are positioned so that they interact constructively with the upwash behind the wing tips and, with careful design, can significantly reduce drag to improve efficiency, without reducing the handling qualities or adding unduly to the structural loads on the wing. Compared to a tailless swept wing of similar overall span, the outboard tail has a greater moment arm than if it were attached directly to the wing, while the wing need not sweep back so sharply as to have undesirable side effects. The outboard elevators can also be used as secondary ailerons, increasing the effective control area. This reduces the variation of loading on the wing during critical manoeuvres such as landing and allows a higher design loading for the wing. This in turn allows greater safety margins when landing. Vertical tail fins traditionally provide directional stability and control. In outboard configuration they can also enhance airflow and contribute to overall efficiency, in a manner analogous to winglets.

History

The configuration was first patented in 1942 by French designer Robert Aimé Robert. It was developed during World War II by German designers Richard Vogt and George Haag at Blohm & Voss. In order to test the proposed control system, Škoda-Kauba adapted the V-6 design as the SK SL6 in 1944. Blohm & Voss then incorporated the design into the P 208 pusher-engined fighter proposal. Although it was not taken up, modern analysis has shown that it would have been viable. B&V went on to produce a series of design studies and project submissions for similar jet fighters. These included the P 209.01, P 210 and P 212. B&V finally received an order for the P 215 all-weather fighter just weeks before the war ended, so it was never built. During the late 1950s and early 1960s the principles of the outboard tail were re-investigated by NASA (formerly NACA) engineers, as a part of their research programme into design configurations for supersonic flight. They conducted analyses and wind tunnel model tests at both subsonic and supersonic speeds. Vought studied the layout for their ADAM V/STOL design project. Further extensive studies were made by J. A. C. Kentfield and colleagues at the University of Calgary, Canada, from the 1990s on. Burt Rutan at Scaled Composites became interested in the configuration for its potential as a variable-geometry stabiliser on a spaceplane. During atmospheric re-entry from space, the tail would rotate vertically to stabilise the plane, the rest of which remained horizontal but fell near-vertically. His first prototype, the Scaled Composites SpaceShipOne took to the air in 2003. It has since also flown on the improved SpaceShipTwo and forthcoming SpaceShip III. The outboard tail is also seen as a natural partner to the FanWing concept and a model was flown in 2011.

References

Notes

Bibliography Benjamin Darrenougue; "Aircraft Configurations With Outboard Horizontal Stabilizers" (Final year project report), Queens University Belfast, 14 May 2004.[4] Guy Inchbald; "Outside Edge", The Aviation Historian, No. 38, 2022. pp.106-118. Kurt W. Muller; "Analysis of a Semi-Tailless Aircraft Design" (Master's thesis), Naval Postgraduate School, US, 2002.[5] Archived 2022-11-23 at the Wayback Machine Hermann Pohlmann; Chronik Eines Flugzeugwerkes 1932-1945. B&V - Blohm & Voss Hamburg - HFB Hamburger Flugzeugbau (in German). Motor Buch Verlag, 2nd Impression 1982 ISBN 3-87943-624-X.

Illustrations

Worked examples

Example 1 — a first encounter with Outboard tail

Start with the simplest possible case. Write down what Outboard tail claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Outboard tail before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Outboard tail ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Outboard tail

In research: Outboard tail appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Outboard tail in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Outboard tail is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aircraft components, Aircraft wing design, Wing configurations, so understanding it makes those chapters shorter.
In everyday life: Look for Outboard tail outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Outboard tail in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Outboard tail means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Outboard tail out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Outboard tail in simple terms?

Why does Outboard tail matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Outboard tail?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Outboard tail.