# Why Vee Tails?



## KrazyKraut (Aug 5, 2008)

This is not specifically WW2, although there were a few vee tailed ww2 craft. So if this belongs into another section of the forum please feel free to move it.

What are vee tails good for besides eliminating one control surface? Reduced drag? I would think it could lead to a lot of harmonization issues. A few German high speed projects used this type of tail (Me 262 HG II and developments of the He 162). The F-117 has one too, probably more as a part of its stealth tech, though. But apart from that they are out of fashion aren't they?


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## ccheese (Aug 5, 2008)

In aircraft, a V-tail [sometimes called a "butterfly tail"] is an unconventional arrangement of the tail control surfaces that replaces the traditional fin and horizontal surfaces with two surfaces set in a V-shaped configuration when viewed from the front or rear of the aircraft. The rear of each surface is hinged, and these movable sections, sometimes called ruddervators, combine the tasks of the elevators and rudder. The arrangement was invented by Polish engineer Jerzy Rudlicki in 1930, and first tested on a modified Hanriot H-28 trainer in 1931.

The V-tail has not been a popular choice for aircraft manufacturers. The most popular V-tailed aircraft in mass production was the Beechcraft Bonanza Model 35, often known as the V-tail Bonanza or simply V-Tail. Other examples include the F-117 Nighthawk stealth fighter, the Fouga Magister trainer, and the RQ-1 Predator UAV. The X-shaped tail surfaces of the experimental Lockheed XFV were essentially a V tail that extended both above and below the fuselage. Over 2000 Ultraflight Lazair ultralights were produced, all featuring an inverted V-tail.

Ruddervators have also been used on some airships, such as the US Navy's N class blimps. Accurate pitch trimming of airships can be difficult and this configuration improves clearance beneath the tail.

*Advantages*
With fewer surfaces than a conventional tail or a T-tail, the V-tail is lighter and produces less drag. In modern day light jet general aviation aircraft such as the Cirrus Jet or Eclipse 400, the power plant is often placed outside the aircraft to protect the passengers and make certification easier. In such cases V-tails are used to avoid placing the the vertical stabilizer in the exhaust of the engine, which would disrupt the flow of the exhaust reducing thrust, and wear on the stabilizer, possibly leading to damage over time.


*Disadvantages*
Combining the pitch and yaw controls is difficult and requires a more complex control system. The V-tail arrangement also places greater stress on the rear fuselage when pitching and yawing.

In the mid-1980s, the Federal Aviation Administration grounded the Beechcraft Bonanza due to safety concerns. While the Bonanza met the initial certification requirements, it had a history of fatal mid-air breakups during extreme stress, at a rate exceeding the accepted norm. The type was deemed airworthy and restrictions removed after Beechcraft issued a structural modification as an Airworthiness Directive.

This from Wiki...... pretty much sez it all...

Charles


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## timshatz (Aug 5, 2008)

Heard the Bonanza V Tail was a real turkey. Kept having the things shed their tails and go in. Not a happy thought for the owners. The FAA kept trying to fix it but they didn't have much luck until somebody came home in a Bonanza with the tail hanging half off (must've been a hell of a pilot).


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## Matt308 (Aug 5, 2008)

There was a thread discussing this long ago. If you diagram the force moments on a v-tail you will quickly realize that you introduce yaw moments during pitch maneuvers and vice versa. The only reason these moments do not result in changes in aircraft direction is that they are met with equal and opposite moments by the opposite side of the v-tail.

But even though these moments were aerodymically cancelled, they still had to be absorbed by the airplane structure. And this is what led to structural failure.


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## FLYBOYJ (Aug 5, 2008)

Perfectly put Matt - it also didn't help that the control push rods going to the stabilizers were corroding from the inside out! Another AD!


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## evangilder (Aug 5, 2008)

Weren't the V-tail bonanzas called "doctor killers"?


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## FLYBOYJ (Aug 5, 2008)

evangilder said:


> Weren't the V-tail bonanzas called "doctor killers"?



and/or lawyer killers....


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## Matt308 (Aug 5, 2008)

lawyer makers more like it.


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## syscom3 (Aug 5, 2008)

Matt308 said:


> lawyer makers more like it.


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