Lower aspect ratio wings stall at higher angles of attack and so it follows that the horizontal stabilizer should have a lower aspect ratio so that control authority is still available after the wing has stalled.A typical aspect ratio for a vertical tail is in the range of 1.3 to 2.0 (here the aspect ratio is based on the span from root-to-tip as the span from tip-to-tip has no meaning in the case of a vertical stabilizer).Longitudinal static stability (will the aircraft return to a neutral state after an upward or downward gust).Directional static stability (will the aircraft return to a neutral state after a cross-wind gust).VMCA calculation (is the aircraft able to maintain directional control with one engine inoperative at a speed close to stall).Longitudinal and Lateral trim calculation (is the aircraft able to remain in trim for a variety of speeds and altitudes). Thanks.Being a person supposedly schooled in aerodynamics, I am surprised that he did not once mention decalage, or the angle betweein the stab and the wing. and the center of pressure (downforce) of the horizontal stabilizer. Once the stabilizer area is know, the planform can be sketched out after selecting an aspect and taper ratio (the.The following are some general rules of thumb that may prove useful when specifying the horizontal and vertical tail planform area:The empirical method outlined above is useful as a first approximation as to the size and shape of the stabilizers required. We are not affiliated with Glasair Aviation, LLC., but we maintain a great working relationship. Over the last few days, I continued my work on the Horizontal Stabilizer. A convention arrangement with the tail to the rear of the aircraft will necessitate that the aerodynamic force generated by the horizontal stabilizer be downward in level flight.Another horizontal stabilizer configuration sometimes seen is the Canard configuration. Both stabilizers are fitted with a primary control surface; an elevator to control pitch on the horizontal stabilizer, and a rudder to control yaw on the vertical tail. However, mounting the horizontal stabilizer on top of the vertical tail necessitates that the tail structure be much stronger (heavier) to accommodate the load introduction of the horizontal tail directly into the vertical tail.Somewhere between the two configurations discussed above is the cruciform tail arrangement. And proud that you are in the same RC club as me.Lucas, thanks for sharing your experimental findings!Seventy years ago I frequented “Clover Hill” to watch the aeromodelers of that era trim their rubber-band-powered, stick-and-tissue, free-flight airplanes. Thanks.Great story. In the wing incidence angle testing configuration, the airplane had a 70-inch wingspan with four motors mounted to the wing and seven servos among the five control surfaces. Flying-wings like the Northrop Grumman B-2 Spirit are designed with a reflexed airfoil which allow the aircraft to remain statically stable without a horizontal stabilizer provided the aerodynamic center of the wing is behind the c.g.Similar to the way that the horizontal stabilizer controls the longitudinal stability of an aircraft, the vertical stabilizer is designed to control stability in the directional or yaw axis. With the downward air speed $v_z$ imparted by the wing, lift is: $$L = \frac{b^2}{4}\cdot\pi\cdot\rho\cdot v\cdot v_z = S\cdot c_L\cdot\frac{v^2}{2}\cdot\rho$$,$S$ is the wing area and $c_L$ the overall lift coefficient. It seems to me that a lot of builders go the extra mile when mating the wings to get things exactly as they should be with respect to the sweep and angle of incidence of the wing. If adjusting the flap stops and flap actuator rods out to move the flaps down, less forward trim would be required. The fuselage angle relative to the flight path or the wing / control surface determines only how much drag is created by the fuselage. Angles of incidence of about 6° are common on most,https://en.wikipedia.org/w/index.php?title=Angle_of_incidence_(aerodynamics)&oldid=899399699,Creative Commons Attribution-ShareAlike License,This page was last edited on 29 May 2019, at 19:52. It only takes a minute to sign up.It 'appears' that in most flights the horizontal stabilizer is set for positive angle of attack.So does this produce an 'up force' (lifting force) on tail thus making the aircraft nose-heavy?Or does the horizontal stablizer presents itself to the relative air at a different angle of attack than the wing does (which creates down force on tail)?You are right, the horizontal tail of a conventional airplane appears to have a higher incidence, but the actual angle of attack is smaller than that of the wing.The wing, flying ahead of the tail, produces downwash, so the flow at the tail location has a distinct downward component. sits ahead of the wing’s center of lift. The two tail surfaces are shown below in a conventional layout pictured on a Cessna 172.The tail assembly (horizontal and vertical stabilizer) is also known as the empennage which originates from the French term.An aircraft tail has two primary objectives:There are a number of common empennage arrangements that most aircraft adhere to. One advantage of the T-tail arrangement is that the horizontal tail acts as an end-plate for the vertical tail. Hello highlight.js! Some vertical stabilizers will have a slight angle of incidence to counter left turning tendencies. I've spent a lot of time lately thinking about airflow over these surfaces and how important tiny imperfections can become. Any comments on this would be most appreciated. A positive incident angle of the wing provides this lift and the control surface is producing that incident with up elevator. A good starting point is to first study existing aircraft of similar size and configuration, and to use this as a basis for sizing your design. If we determine a change in horizontal stabilizer angle of incidence is necessary it would most likely be a leading edge up position of only 1/4″ to 1/2″ relative to water line 100. This makes the vertical tail more aerodynamically efficient which means it can be reduced in size.