1. This is due to the fact that the stabilator sits up out of the propwash, and so is less effective at low airspeeds. The reason for this is the reversal of the $C_M$ - $\alpha$ slope of T-tails, as depicted below. Another major difference between these two configurations concerns the stability. 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. Is there a proper earth ground point in this switch box? Why did the F-104 Starfighter have a T-tail? Not so! 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. The 200-HP Piper Arrow is an unremarkable performer; the 180-HP version is, well, doggy. (before we beat them up). In the 1960s, several passenger jets with rear-fuselage-mounted engines featured T-tails, such as the BAC One-Eleven, the Vickers VC10, the McDonnell Douglas DC-9, the Boeing 727, the Fokker F28 Fellowship, and the Russian Ilyushin Il-62 and Tupolev Tu-154. Planes operating at low speeds need clean airflow for control. Accident, incident and crash related photos, Air to Air Not only that, but on aircraft where the engines are mounted on the tail section, it puts the tail out of the way of the exhaust. With all these advantages, why at least some of commercials does not consider this solution? Stabilizers on first Douglas DC-4 model: 5 (three above, two below) A stabilizer in undisturbed airflow will produce better L/D than in turbulent flow, as well. Subscribe to get the latest videos, articles, and quizzes that make you a smarter, safer pilot. This is a lot lower compared to the Fenestron RPM of roughly 3150 RPM (about 50% higher RPM! Get Boldmethod flying tips and videos direct to your inbox. Beechcraft 1900 D of the Swiss Air Force. Joined: Sep 1, 2008 Messages: The effect of this is that the tail will be pushed left. I wonder if full scale requires additional considerations on those tails. 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. How do I connect these two faces together? If they were better, they would be used everywhere, and mostly they are not. Why is this the case? Easy to recover from spin: It is easy to recover from a spin with this type of design because the elevator is located above the rudder. T-tails are often used on regional airliners and business jets. We thank you for your support and hope you'll join the largest aviation community on the web. Helicopters & rotorcraft, airships, balloons, paragliders, winged suits and anything that sustains you in the air is acceptable to post here. Quiz: Could You Pass An Instrument Checkride Today? Create an account to follow your favorite communities and start taking part in conversations. The simple answer is that they can be more efficient than a conventional tail. T-tails have a good glide ratio, and are more efficient on low speed aircraft. A T-Tail design is an aircraft configuration in which the tail control surfaces with the horizontal surface are mounted on top of the aircraft fin forming a T look when viewed from the front. an aft CG, T-tail aircraft may be more susceptible to a deep stall. How can this new ban on drag possibly be considered constitutional? The T-tail raises the tailplane out of the fuselage drag-hole which can reduce your tailplane effective aspect ratio by 20% or more. The considerations in the roe's answer are entirely correct but there might be other factors to take into account. [1] Rear-mounting the engines keeps the wings clean and improves short-field performance. Typical aspect ratios are about 4 to 5. Quiz: Can You Identify These 7 Cloud Formations? 1. Get access to additional features and goodies. Elevator operation in undisturbed air allows control movements that are consistent throughout most flight regimes. Photos taken by airborne photographers of airborne aircraft, Special Paint Schemes 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. Here are some habits that VFR pilots can pick up even before they become IFR certified. Views from inside the cockpit, Aircraft Cabins The T-tail stays out of ground effect for longer than the main wing. Why do T- tail airplanes have a shorter vertical stabilizer? Doubling the cube, field extensions and minimal polynoms, A limit involving the quotient of two sums. Together they are referred to as the empennage, which has French origins and translates to "feather an arrow". And on the landing roll the tail can seem to lose authority all at once with the nose coming down. ). with the high t-tail of the lance it makes that a bit more difficult. When the vertical tail is swept, the horizontal tail can be made smaller because it is further rearwards and therefore has a greater lever arm. However, T-tails are more likely to enter a deep stall, and is more difficult to recover from a spin. Our large helicopter section. When flying at a very high AOA with a low airspeed and Depending on the lift characteristics and generall geometric shape of the wing, this vortex results in updraft and downdraft zones. As your AOA increases the wash from the wings will come closer and closer to the tail, not further, and so your tail will become more and more inundated by the wash, rather than less in the case of a conventional tail. 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). What are the differences though? Less drag: In a T-tail design, the arm of the CG is made smaller. 3. 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. Reduced and zero tailswing models have become popular due to their easy maneuverability in urban and residential areas where space is limited. Quiz: Can You Answer These 7 IFR Checkride Questions? Is the compressive load from the stabilator that much more than the bending load of the rudder. The non-turbo d Arrows consume nine to 12 gallons per hour, with the blown versions using around 14 GPH when pushed. a lot of guys want the straight tail for the look of a 180 imo. Rudder authority: T-tail design gives you a better rudder authority when flying at a very high AOA and stalls thus preventing a spin. Note that the increased leverage means that the horizontal tail can be smaller as well. Some people just think they look cool. [citation needed], The T-tail configuration can also cause maintenance problems. [1], During normal flying conditions, the tailplane of a T-tail is out of the disturbed airflow behind the wing and fuselage,[2] which provides for more consistent elevator response. As a consequence of the smaller vertical tail, a T-tail can be lighter. 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. What airframe design is best for stormy weather? (https://www.airliners.net/discussions/tech_ops/read.main/138372/). Every type from fighters to helicopters from air forces around the globe, Classic Airliners 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. Aside from the aforementioned lack of propwash, because a T-tail is usually further aft and has more lever arm, it can be made smaller, with less overall drag. This is because there is generally less surface area needed for a V-Tail (you have two surfaces cutting through the air, not three). I'd like to learn as much in this area as possible. Prevalence over the years While T-tails are a rarity in modern aviation, they were well spotted in the past. Elevator authority: In a T-Tailed aircraft, the pilot cannot obtain an immediate elevator authority by increasing the aircraft power. In these designs, you can see very peculiar and different ta. The loss of Alaska Airlines Flight 261 was attributed to improper maintenance of the T-tail. ). Many of the regional jets have T tails. In a normal tailed engine aircraft, when the pilot increases power, he gets wind over the tail and has control authority of the aircraft. It has been used by the Gulfstream family since the Grumman Gulfstream II. The T-tail, depending on airspeed, is either very effective or far less effective than a conventional tail, which isnt as prone to abrupt transitions between different flying regimes. Most of the (small aircraft) T-tails I have flown it takes a bit of extra effort to stall the aircraft hard because gently the disruption just lets the nose back down and then you aren't stalled anymore. Combining both the elevator and the rudder will, as with a conventional empennage, cause the plane to rotate around the yaw and pitch axes. Discussion in 'Excavators' started by ror76a, Aug 30, 2007. As we all know, a standard tail uses the rudder for yaw and the elevator for pitch - so how do V-Tail arrangements achieve these two functions? We hope you found this article helpful. This article highlights the pros and cons of using a V-tail configuration. Santa Rosita State Park, under the big 'W', (You must log in or sign up to reply here. Become a better pilot.Subscribe to get the latest videos, articles, and quizzes that make you a smarter, safer pilot. 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. They are marine pathogens. . Copyright SKYbrary Aviation Safety, 2021-2023. The t-tail is a popular design in aircraft with aft fuselage mounted engines (e.g. Observed form behind, this looks like the capital letter T. Sometimes the term is used to refer to an aircraft with such empennage. Moderators: richierich, ua900, PanAm_DC10, hOMSaR, Military Aircraft I have no idea how those loads are calculated much less how they are combined in order to estimate total stress. Save my name, email, and website in this browser for the next time I comment. It got them more weight and less authority in the TO roll and flare. Nahhthe 90 and 100 were pretty good lookin' birds. High mounted horizontal stabilizers remain out of the turbulence of the wings and jetwash at much greater angles of attack. The biggest thing I noticed was that soft field landings were a LOT harder (read almost impossible to keep the nose up) in the T-tail Arrow I flew on my CFI checkride vs. the low tail Arrow. T-tails can cause flutter, such as with the Lockheed C-141 Starlifter. ARv is about 1.2 to 1.8 with lower values for T-Tails. Provides smooth flow: A T-tail ensures the tailplane surfaces behind the wings are out of the airflow. Create An Account Here. A T-tail has structural and aerodynamic design consequences. The most noticeable difference is that V tail aircraft are much more sensitive to being loaded tail-heavy. Figure 2.13: Aircrafts empennage types. 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. With the rudder, a right rudder input in the V-tail will lower the right ruddervator and raise the left one. Upon approaching the ground, the increase in wing lift causes an auto-flare: the aircraft lands itself. Beautiful shots taken while the sun is below the horizon, Accidents Sponsorships. Thanks. hmmm "wake size" is quite undefined. Also, approaching a stall, you will have more elevator effectiveness with the T-tail, as the wing wash is below the horizontal stabilizer. 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. 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. The aircraft was sold in 2006 with the thought that I was finished with flying. However, now the fuselage must become stiffer in order to avoid flutter. 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. The wings have such a large chord that there is already 'dirty' airflow coming off of them. Why do big modern airplanes not use a T-tail configuration for the horizontal stabilizer? avoiding hard de-rotation on touchdown, issues at high AOA, etc)? I have had several mechanics and old timers tell me my conversion is one of the best they have seen. A T-tail produces a strong nose-down pitching moment in sideslip. The airplane lands in typical crosswind with no issues. To learn more, see our tips on writing great answers. With tricycle landing gear, the secondary wheel is in front of the two primary wheels. If "all flying rudders" for LSA aircraft need up to 40% less area, what about "all flying elevators (stabilators)"? The Boeing 737 was initially planned with rear-mounted engines, like the Sud-Aviation Caravelle, which it was meant to replace. 3 7 comments Add a Comment [2], T-tail aircraft can have better short-field performance,[2] such as on the Avro RJ-85. I guess I'd like to know what makes a T-tail advantageous as opposed to a conventional tail. Making statements based on opinion; back them up with references or personal experience. 5. 6. On a quote, I am averaging 2.50 per device difference between conventional and PT. The arrangement looks like the capital letter T, hence the name. [3], The design and structure of a T-tail can be simpler. Compare this to unstable conventional tailed planes such as the Super Hornet, Raptor, and Lightning which are all 50+ AoA fighters. There can be practical considerations, like them being less likely to drag in the grass. Why are the Antonov An-124 horizontal stabilisers directly behind the wings? In a normal tailed engine aircraft, when the pilot increases power, he gets wind over the tail and has control authority of the aircraft. Lighter: V-tail-designed aircraft is lighter compared to the conventional tail configuration of other aircraft designs. Quiz: 7 Questions To See How Much You Know About VFR Sectional Charts, Quiz: 7 Questions To See If You Can Fly The LOC/DME-E Approach Into Aspen. Though on most aircraft the horizontal stabilizer does indeed produce negative lift, for positive stability it is only required that the rear surface flies at lower angle of attack than the forward surface. MCDONNELL DOUGLAS MD-82) because it removes the tail from the exhaust blast. Connect and share knowledge within a single location that is structured and easy to search. (Picture from the linked Wikipedia article). 6. The disadvantages ot the T-tail concept are the mentioned deep stalls, maybe a elevator stall during flare, unfavourable C.G. somewhat difficult to align.. lots of ground clearance when landing. It can help to increase the effectiveness of the vertical tail by keeping the air on both sides of it separated. I can't really say I know the aerodynamics of it though, so I might be very mistaken. All of the Boeings except the 717 have conventional tails. The T-tail increases the effectiveness of the vertical tail because of "end plate" effect. Not sure that's a T tail thing, you can hold the nose wheel off for ever in the PC12. On takeoff the nose can "pop" up in a different manner than a more conventional tail. All rights reserved. If OT and PD cost me 25 dollars and hour more than standard time, I have to do 50% more devices at trim out per hour to break even. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Page 1 of 3 1 2 3 Next > ror76a Well-Known Member. With a minimized counterweight radius, the excavator. All rights reserved. High performance: It results in high performance of aerodynamics and also ensure there is an excellent glide ratio since the empennage is not affected by the wing slip steam. Both military and civil versions, Blimps / Airships This is the small wing-like protrusions from the main tail, or rear of the fuselage. During that time, I never experienced an unusual attitude or soiled pants. MathJax reference. 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. Quiz: Can You Identify These 6 Uncommon Airport Lighting Systems? This gives them greater authority and consistency over a wider flight regime, but unfortunately also means you will have the authority to worsen a developing stall. A T-tail has structural and aerodynamic design consequences. One advantage of the T-tail arrangement is that the horizontal tail acts as an end-plate for the vertical tail. 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. What you get is the horizontal stab up out of the prop wash, which reduces inflight vibration -- the reason, I believe, which Piper did it. 9. Started, Advertising & In a thermonuclear weapon, often called a hydrogen bomb, the fission process is only the beginning. uhmmm very interesting but now I can't understand why commercial airliner strictly prefer conventional tail instead of T-Tail. I would be keeping that in mind if I ever had an emergency in the plane. Obviously MD-80s aren't shedding their tails in flight but. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. The vertical tail fin (with the airline logo on it) is technically called the vertical stabilizer. It is structurally more compact and aerodynamically more efficient. Finally, at a lower level but still a difference, using a T-tail increases the wake (compared to a conventional configuration, where the tail is almost in the wake of the main wings and the fuselage) behind your aircraft and thus the drag you need to overcome is larger. Frequent air travellers would have noticed different aircraft for longer and shorter air routes.
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