Most aircraft feature empennage incorporating vertical and horizontal stabilizing surfaces which stabilize the flight dynamics of pitch and yaw as well as housing control surfaces. T-tails must be stronger, and therefore heavier than conventional tails. Making statements based on opinion; back them up with references or personal experience. A given T, V, or conventional tail will all have essentially the same control authority if they have the same total area. Anything related to aircraft, airplanes, aviation and flying. From my reading, they take a longer take off roll and higher speed on approach. in large a/c deep stalls can get quite stable because of fuselage lift and (especially in case of airliners) sweptback wings that move center of pressure forward when stalling. Page 1 of 3 1 2 3 Next > ror76a Well-Known Member. 8. It was used in the 1950s by combat aircraft such as the Gloster Javelin, McDonnell F-101 Voodoo, and Lockheed F-104 Starfighter interceptors, and on the Blackburn Buccaneer attack aircraft. T-tails have a good glide ratio, and are more efficient on low speed aircraft. Legal. Incorrect Traffic Pattern Entry Leads To Mid-Air Conflict, How To Correct A High Flare During Landing. T-tails may be used to increase clearance at the rear of a cargo aircraft such as the Boeing C-17 Globemaster, to provide extra clearance when loading the aircraft. ARv is about 1.2 to 1.8 with lower values for T-Tails. The C2 has a conventional tail rotor: The RPM of the tail rotor on the C2 is roughly 2150 RPM. easiest to do. The Pilot Handbook of Aeronautical Knowledge has a whole section talking about T-tails. MathJax reference. Frequent air travellers would have noticed different aircraft for longer and shorter air routes. This article is for you. High mounted horizontal stabilizers remain out of the turbulence of the wings and jetwash at much greater angles of attack. Pictures of great freighter aircraft, Government Aircraft The stall speed must be demonstrated during certification, and safe recovery from a stall is a requirement. Let me repeat that, just in case you missed it . For smaller aircraft though it is very difficult to hold nose high enough to overshadow a T-tail. Rudder authority: T-tail design gives you a better rudder authority when flying at a very high AOA and stalls thus preventing a spin. Don't have an account? 10. Learn more about Stack Overflow the company, and our products. Figure 2.13: Aircrafts empennage types. Together they are referred to as the empennage, which has French origins and translates to "feather an arrow". On the positive side you have a less noisy cabin (lets say in front of the by design clean wing). On light airplanes, the primary reason that T-tails were used was aesthetics. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. What do labyrinthulids do? Dunno. an aft CG, T-tail aircraft may be more susceptible to a deep stall. The main hazard with this design is the possibility of entering aDeep Stall. The optimal treatment strategy for acute exacerbation of COPD in the ICU next to the well-known benefits of noninvasive ventilation (NIPPV) is unknown ERROR: CREATE MATERIALIZED VIEW WITH DATA cannot be executed from a function. Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site. I have heard a conventional tail has better stall recovery characteristics than a T-tail. Tailplane forces: The vertical stabilizer should be made stronger and stiffer in order to support all the forces generated by the tailplane. Not so! Seaplanes and amphibian aircraft (e.g. 3 7 comments Add a Comment It only takes a minute to sign up. A T-tail has structural and aerodynamic design consequences. normally I really get into the tail and look at every nut, bolt, rivet, piano hinge and control connection I can see. The disturbed airflow over a lower stabilizer can make control more difficult at lower speeds. receive periodic yet meaningful email contacts from us and us alone. Asking for help, clarification, or responding to other answers. The fan consists of between 8-18 blades, depending on the aircraft model, and is of a much smaller diameter than a conventional tail rotor system. Reduces stick lightening: The greater height of T-tail can help reduce stick lightning caused by the conventional tail after entering the wake while maneuvering. Typical values are in the range of 8% to 10%. First, it is true that using conventional tail leads to the fact that the airflow over the tail might be disturbed by the main wing and/or the engines and/or the fuselage. Copyright SKYbrary Aviation Safety, 2021-2023. Press question mark to learn the rest of the keyboard shortcuts. He graduated as an aviation major from the University of North Dakota in 2018, holds a PIC Type Rating for Cessna Citation Jets (CE-525), is a former pilot for Mokulele Airlines, and flew Embraer 145s at the beginning of his airline career. one thing I noticed was on preflight. Here's how they're different than conventional tail configurations. Different configurations for the empennage can be identified (See Figure 2.13): The conventional tail (also referred to as low tail) configuration, in which the horizontal stabilizers are placed in the fuselage. Passenger cabin shots showing seat arrangements as well as cargo aircraft interior, Cargo Aircraft Rear mounted engines also require more fuselage structure. Not only for the aerodynamic loads, but for the elevator and elevator trim mechanisms. In the 1970s it was used on the McDonnell Douglas MD-80, and the Russian freighter Ilyushin Il-76, as well as the twin turboprop Beechcraft Super King Air. (However, T-tail aircraft may be vulnerable to deep stall, see Disadvantages below. Advantages Of A T-tail Vs. A Conventional Tail, RE: Advantages Of A T-tail Vs. A Conventional Tail. I wonder if full scale requires additional considerations on those tails. On a quote, I am averaging 2.50 per device difference between conventional and PT. Boldmethod 4) Control Forces However, once in the stall, the wings wash can blanket the elevators, making them much less effective. On takeoff the nose can "pop" up in a different manner than a more conventional tail. Lighter: V-tail-designed aircraft is lighter compared to the conventional tail configuration of other aircraft designs. We hope you found this article helpful. All rights reserved. The vertical tail can be shorter due to the end plate effect of the horizontal tail, and the moment arm to the CoG is longer - however for most higher subsonic speed aircraft these effects merely reduce the weight penalty. This is because there is generally less surface area needed for a V-Tail (you have two surfaces cutting through the air, not three). Confused by the V-Tail? - I would guess that a T-tail necessitates a stronger, and thus heavier fin. Pilots must be aware that the required control forces are greater at slow speeds during takeoffs, landings, or stalls than for similar size aircraft equipped with conventional tails. More susceptible to damaging the aft fuselage in rough landings. A conventional tail tends to drag the stabilizer through the grass on landing, hooking tips and causing massive bending loads on the tailboom. The under-sized surfaces used in designing the V-tail make it lighter and faster. The arrangement looks like the capital letter T, hence the name. Get below 95 kts on final (especially with just one or two people up front) and the wing will start to blank out the tail and things get squirrely. You just compared RC airplane design and quality to FAA certified airplane design and quality. [citation needed], The T-tail configuration can also cause maintenance problems. Designers were worried that an engine failure would otherwise damage the horizontal tail. The aeroplane is aerodynamically stable when the $C_M$ - $\alpha$ slope is negative, such as in cases B and C. For configuration A, the slope becomes positive after the stall point, meaning that the nose wants to increase upwards after reaching the stall - not a good situation. To give the perfect example let's have a look at the EC145 C2 and compare it to the H145 / EC145D2. This distance gives the plane leverage and enables the tailplane to control the aircrafts pitch attitude. The advantage for the upright V-tail in models is usually primarily structural. A T-tail may have less interference drag, such as on the Tupolev Tu-154. Airport overviews from the air or ground, Tails and Winglets What design considerations go into the decision between conventional tails and T-tails? 9. ), An aircraft with a T-tail may be easier to recover from a spin, as the elevator is not in a position to block airflow over the rudder, which would make it ineffective, as can happen if the horizontal tail is directly below the fin and rudder.[4]. Lets take a look at the pros and cons of this arrangement. With taildragger landing gear, the secondary wheel is behind the two primary wheels. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. The T-tail avoids this, but it places a large mass (the stabilizer) at the end of a long moment arm (the fin). Yikes! Conventional-tail-swing excavators are most often operated in excavating, grading and site development where space constraints are not a concern. Views from inside the cockpit, Aircraft Cabins A T-tail produces a strong nose-down pitching moment in sideslip. If You Go-Around On A Visual Approach Under IFR, Do You Need To Contact ATC Immediately? Airliners.net is the leading community for discovering and sharing high-quality aviation photography. Compare this to unstable conventional tailed planes such as the Super Hornet, Raptor, and Lightning which are all 50+ AoA fighters. In fact, I was under the impression that a major disadvantage of a T-tail was that the wash during a stall could envelope the tail and remove the authority needed to correct the situation. The reason for this is the reversal of the $C_M$ - $\alpha$ slope of T-tails, as depicted below. Thanks. The FAA has issued a draft of the AC on Flightpath Management and it includes a host of measures the agency wants operators to include in training and operations to ensure pilots can get from A to B safely. For the most part this is correct, although if airflow is disrupted over the tail the nose should actually come down because the horizontal stabilizer is what holds the nose up in the first place. However both halves typically have to be larger in surface area to make up for only having two stabilizing surfaces, so the drag reduction is rendered null. I too love the look of a V tail, and soon enough ill be trying my first V tail home build! The T-tail increases the effectiveness of the vertical tail because of "end plate" effect. Cruciform tails are often used to keep the horizontal stabilizers out of the engine wake, while avoiding many of the disadvantages of a T-tail. Aviation Stack Exchange is a question and answer site for aircraft pilots, mechanics, and enthusiasts. Why would a stretch variant need a larger horizontal stabilizer? I would say that the use of V tails has almost nothing to do with performance. Quiz: Can You Identify These 6 Uncommon Airport Lighting Systems? Manufacturing cost because the vertical stabilizer needs to be built that much stronger to handle additional mass and aerodynamic forces that are now on the end of a long, slender lever. In a T-tail configuration, the elevator is above most of the effects of downwash from the propeller, as well as airflow around the fuselage and/or wings. When flying at a very high AOA with a low airspeed and For example, the T-tail Arrows have a small tendency to blanket the airflow to the tail in certain angles of attack. Either way it makes more sense to have a pitch up tendency when appying more thrust. Do I need a thermal expansion tank if I already have a pressure tank? Yes the T tail requires a bit more speed for elevator authority to rotate on takeoff. Cruise speeds range from 130 (180-HP) to 143 knots (normally aspirated 200-HP T-tail) and as high as 170 knots for a turbocharged version flown in the teens. Santa Rosita State Park, under the big 'W', https://m.youtube.com/watch?v=svRIi_cgtJE, (You must log in or sign up to reply here. However, T-tails are more likely to enter a deep stall, and is more difficult to recover from a spin. Already at the earliest time point (i.e., 0.75 hpf) and much more prominently later (i.e., 5.5 hpf), we detected a . The uninitiated pilot can overcontrol a bit at this point, but one soon gets used to it. Press J to jump to the feed. Which T-tail airplanes have you flown? Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. My thoughts on 159 hours in rented T-tail Turbo Arrows One nice feature on my Sky Arrow is that the position of the CG means that if you lower the tail to the ground it stays there: I think the OP was asking about 'real' planes. The aircraft was sold in 2006 with the thought that I was finished with flying. 1. T-tails also have a larger cross section. I think to have the engines underneath the wing and a conventional tail is the better concept (hence why most of the new airliners are like that). This arrangement is different from the normal design where the tailplane is mounted on the fuselage at the base of the fin. This may result in loss of elevator authority and consequently, inability to recover from the stall (i.e. What leaves me questioning is that almost all large commercial aircraft feature a conventional tail (B747, B777, A340, A380) while most military aircraft of a similar or larger size have a t-tail (C-17, C-5), and then if you get even larger (AN124, AN225) you're back to having a conventional tail again. This shape resembles a capital T, giving birth to the moniker of T-tail. In comparison with conventional-tail aircraft, the elevator on a T-tail aircraft must be moved a greater distance to raise the nose a given amount when traveling at slow speeds. Why is there a voltage on my HDMI and coaxial cables? Zero tail swing vs normal tail swing. Seaplanes and amphibian aircraft (e.g. Many large aircraft can have the fin and rudder fold to reduce height in hangars, however this generally isn't feasible or useful if there is a T-tail. Why is this sentence from The Great Gatsby grammatical? The forces required to raise the nose of a T-tail aircraft are greater than the forces required to raise the nose of a conventional-tail aircraft. I am not so sure about your argument for added drag @yankeekilo But you do agree that the wake is wider? 3. Why is this the case? I'd like to learn as much in this area as possible. 72V Well-Known Member . T-tails can cause flutter, such as with the Lockheed C-141 Starlifter. or I can't really say I know the aerodynamics of it though, so I might be very mistaken. Discussion in 'Hangar Talk' started by SixPapaCharlie, Oct 4, 2015. Rotate at 75 knots. Quiz: Could You Pass An Instrument Checkride Today? And it weighs more, because the vertical stab has its original task (yaw stability and control) as well as now having to take the horizontal stab's pitch loads, and the torque loads that a horizontal stab can also generate due to spiralling propwash, turbulence, and so on. [citation needed] T-tails can be harder to inspect or maintain, due to their height.[3]. It ensures clean airflow, at least on gulfstream aircraft. And on the landing roll the tail can seem to lose authority all at once with the nose coming down. Create An Account Here. If "all flying rudders" for LSA aircraft need up to 40% less area, what about "all flying elevators (stabilators)"? With the conditions you said you operate in I would go with a conventional tail swing, talk to a cat road mechanic about servicing/repairing. While this can occur on other aircraft as well, the risk is greater with T-tails as a highAOAwould likely place the wing separated airflow into the path of the horizontal surface of the tail. Pros: 1. You might see V-Tails used on high-performance models, such as slope soaring or discuss launch gliders. Why do modern aircraft tend to have angular tails? The horizontal force generated is "wasted" in essence as it does not contribute to the desired pitch outcome. The 200 and 300 not so much. This is because there is generally less surface area needed for a V-Tail (you have two surfaces cutting through the air, not three). With heavy attachments or loads the zero swing is likely to pitch more than a conventional machine. 5. Reduces stick lightening: The greater height of T-tail can help reduce stick lightning caused by the conventional tail after entering the wake while maneuvering. (Picture from the linked Wikipedia article). YouTube Channel: www.youtube.com/projectairaviation, - Find this article & others like it at www.FliteTest.com -, By joining our mailing list via the home page or during checkout, you agree to MCDONNELL DOUGLAS MD-82) because it removes the tail from the exhaust blast. T-tails were common in early jet aircraft. [citation needed], The vertical stabilizer must be made stronger (and therefore heavier) to support the weight of the tailplane. [1], The aircraft may be prone to deep stall at high angles of attack, when airflow over the tailplane and elevators is blanked by the wings. The single-engine turboprop Pilatus PC-12 also sports a T-tail. Provides smooth flow: A T-tail ensures the tailplane surfaces behind the wings are out of the airflow. Tailplane more difficult to clear snow off and access for maintenance and checking. In an aircraft with wing mounted engines you get a pitch up moment when you apply thrust (but most of the time if you have to increase thrust its because you are on speed and below profil or on speed but below profil). Create space for the engine: Have the tail surface mounted away from rear fuselage creates space for mounting engines. Note: This is really depending on the details, the. The main advantage of a T-tail is that during normal flight conditions the elevator is above most of the effects of downwash from the propeller (in case of a propeller-driven aircraft) and the airflow around the fuselage and wings. This is because the conventional-tail aircraft has the downwash from the propeller pushing down on the tail to assist in raising the nose. position if empty. Quiz: Can You Answer These 5 Aircraft Systems Questions?