飛行最美--輕航機世界

關於在降落的時候FLAP對於飛輕航機的我們有什麼幫助呢?他可跟軍機的使用效應可有大大的不同.軍機翼面積小,完全都是靠推力來保持升力,就算FLAP FULL的情況之下能有多大的改變,速度快的機種都是維持一個速度就會產生一個姿態,當落地外型全放時,軍機的攻角甚至可以高到無法由前方來目視跑道,只能看著左右來判斷進場的下沉率,FINAL 最低速度可高達160海浬,但是話說回來,跑道很長(12000FT),壓力也相對減少,反觀輕航機受限於環境使然,跑道大多都在300m左右,您降落的習慣為何?FAA CH8 就有詳細的提到,FLAP使用好處多多,尤其針對輕航機個人認為降落時能夠降低FINAL空速,增加進場俯角,落地後使用最少的跑道,.這是最安全的保障,讓我們先來探就使用FLAP的優點在哪裡.The lift/drag factors may also be varied by the pilot to adjust the descent through the use of landing flaps.[Figures 8-3 and 8-4] Flap extension during landings
provides several advantages by:

•Producing greater lift and permitting lower landing speed.
• Producing greater drag, permitting a steep descent angle without airspeed increase.
• Reducing the length of the landing roll.

簡言之就是提供了更好的升力及獲得更低的操縱速度,產生更大的阻力可獲得更大的下降角,(但空速不會大量增加) 減低落地後使用跑道的距離。套用在我們常飛的環境裡,落地後剩餘跑道不夠長,往往停下來只剩下1/3不到,如果此時煞車失效了怎麼辦?正式的機場有攔截網,但是我們有嗎?跑道頭有障物，必須飛越障礙物後再迅速增加俯角,尤其Storch CL此款機型減速慢,若增加俯角速度飆來可快的,除了增加了操作的困難度之外,落地touch點又會往後延伸,縮短了剩餘跑道距離,假如我們可以善用FLAP FULL 來完成落地程序,那麼先天不良的問題即可大幅改善,但是切忌,輕航機不要在轉彎中改變外型,希望可以在 Incremental deflection  of flaps on downwind, base leg, and final approach中完成,此外若遇到了降落過程中需要重飛也不要急於收起你的FLAP.. Never retract the flaps to correct for undershooting   since that will suddenly decrease the lift and cause the airplane to sink even more rapidly.待爬升到安全高度飛機保持水平之下再收起你的FLAP... Flap deflection of up to 15° primarily produces lift with minimal drag. The airplane has a tendency to balloon up with initial flap deflection because of the lift increase. The nosedown pitching moment, however,tends to offset the balloon. Flap deflection beyond 15°
produces a large increase in drag. Also, deflection beyond 15° produces a significant noseup pitching moment in high-wing airplanes because the resulting downwash increases the airflow over the horizontal tail.
The time of flap extension and the degree of deflection are related. Large flap deflections at one single point in the landing pattern produce large lift changes that require significant pitch and power changes in order to maintain airspeed and descent angle. Consequently, the deflection of flaps at certain positions in the landing pattern has definite advantages. Incremental deflection
of flaps on downwind, base leg, and final  approach a llow smaller adjustment of pitch and power compared to extension of full flaps all at one time.
When the flaps are lowered, the airspeed will decrease unless the power is increased or the pitch attitude lowered. On final approach, therefore, the pilot must  estimate where the airplane will land through discerning judgment of the descent angle. If it appears that the airplane is going to overshoot the desired landing spot, more flaps may be used if not fully extended or the power reduced further, and the pitch attitude lowered. This will result in a steeper approach.
If the desired landing spot is being undershot and a shallower approach is needed, both power and pitch attitude should be increased to readjust the descent angle.