Category Archives: Aircraft Learning & Helicopter Teaching: Syed Mohd. Saleh Uddin

Aircraft Learning & Helicopter Teaching: Syed Mohd. Saleh Uddin

Aircraft Learning & Helicopter Teaching

 

Syed Mohd. Saleh Uddin, Ex CI NIET & College of Aviation Technology, Assist. Professor (Retd)

 

 

 

 

Are you the students of Aerospace Engineering or Avionics Engineering? This story is for you and also for your instructors. It is rather two stories. It’s one is how I learnt it in SOA, PAF i.e School of Aeronautics of the Pakistan Air Force. I had a chance to study this subject there. This School is in PAF Korangi Creek of Karachi till now.

It was 1970. Just I joined there for my Basic training. There were students of Iranian Air Force, Libyan Air Force. Saudi Air Force, Iraqi Air Force, trainees of Pakistan Army Aviation and Engineers of Pakistan Plant Protection department and we PAF recruits. There parade was ‘namka wasta’ i.e. for name shake. In the evening there was PT as usual. Aeronautical Engineering and Avionics Engineering both were tough subjects. There in the School of Electronics Avionics subjects were taught. In Korangi Creek also there was a college where officers of Engineering branch were taught and each was awarded Bsc Engineering Degree most probably from Karachi University and airmen after ‘Advanced’ training in SOA and SOE Diploma of Associate Engineering certificate was given that was recognized by the PTEB.

Once in the class room an instructor asked the Question to the class, “What is an aircraft”. That was the time when instructors in the Military institutions Herbert’s five stages methods had to use. There were no power point and also there were so easy projector systems as now. So, instructors had to learn first then entered the class for teaching. Since CI sometimes kept sitting in the hind of the class, the instructor tried to follow method they were taught in their IT course properly .So, he asked the question to the class first. Then most probably he pointed me to answer. This also was according to method. Now I cannot surely say was the instructor was Flt. Sgt. Iqbal or Sgt. Shafi or Sgt. Rashid. They were my instructor in the SOA. My answer was flying related something what he did not like. So he told, “well every one, open your khata (exercise book) and take note, an aircraft is a machine which is designed to fly.”

Later our lesson progressed. We were supplied précis. We had to study. In the library we had opportunity study in due time. In the class room we had to maintain our attention all the time. Instructors used to draw figures or charts in the black board. We had to take note. Now in the defense institutes there is power point or any other projection systems but I do not think now for full class time they utilize that projection systems. According to method for a period certain portion of the time that can be utilized or five stages methods cannot be followed in specified time of 40 minutes or 60 minutes etc. By showing lessons in the over head projectors for whole the class period teacher can pass time and also students lose attention. Because for effective learning, we know, specialist told to utilize all the five senses. Look, listen, smell, touch, do are required for learning. Modern methods emerged for effective learning but it does not mean that prescribed the teachers to avoid familiar method of teaching. For a teacher just entering the class room with a soft ware and put to machine for projection is never suggested in IT. The teacher who are very experienced and know the subject well they may permitted to do so for refreshers level of learners but in no way for the beginners.

Five stages methods suggests, for a teacher following five stages method is obligatory. They are:

  1. Preparation
  2. Presentation
  3. Application
  4. Confirmation
  5. Revision

These I may explain those in other day. New instructors are requested to study books on the ‘Method of Teaching’ subject. In the method following established methods should be utilized:

  1. Lecture
  2. Dictation
  3. Demonstration
  4. Exercise
  5. Lesson

In the Lesson method rest four methods are included to plan Herbart’s five stages method. In the method Power point or other projectors may be utilized for portion of the period.

 

However, how a teacher will teach it is his matter and the policy of the Institutes but I like to tell you something about aircrafts.

 

We were taught primarily aircrafts are two types.

  1. Aero-state. They are lighter than aircrafts.
  2. Aero-dyne. They are heavier than aircrafts.

 

Again Aero- state is two types.

 

  1. Non- guided. Examples: Balloons (free), Kite balloons (used for commercial advertisement) etc.
  2. Powered. Example: Air ship, Zeppelin etc.

Aero-dynes are two types:

  1. Non-conventional. Examples: Ornithopters, Gliders, Sail plane, Flying boats, Sea planes, Amphibians etc.

  2. Conventional.

Conventional aircrafts are two types:

  1. Aero planes. Example: Passenger aircrafts, Military aircrafts etc.

  2. Rotary wing aircrafts: Gyro craft, Helicopter, Convertiplanes (in convertiplane aircraft propellers are converted to rotors displacing its position for vertical takeoff and landing. For level flight rotors again are made propellers by displacing position.) etc.

Passenger aircrafts may be supersonic and subsonic type. Fighter aircrafts may be Hypersonic, Supersonic, and subsonic etc types. Supersonic passenger aircrafts are not yet successful so are not in use. Concorde was banned after few flights. Construction of a successful hypersonic military air craft’s is under research by NASA.

Aero planes again may be divided as:

  1. Conventional wings.

  2. VTOL (vertical takeoff and landing).

  3. STOL (short takeoff and landing).

Names of the few parts of an aircraft are as follows:

  1. Airframe.

  2. Power plant/ Engine

  3. Fuselage.

  4. Wing.

  5. Tail.

  6. Rudder.

  7. Elevator.

  8. Fin.

  9. Aileron.

  10. Nacelle.

  11. Alighting Gear.

  12. Cowling.

Each Fuselage has three section:

  1. Front section.

  2. Center section.

  3. Tail section.

In the aircrafts now a day’s various types of engines are used. They are as follows:

  1. Piston engine (various types).

  2. Jet engine (various Types).

  3. Rocket engine (in high speed aircraft for special use).

  4. Solar engine (in light aircraft under research).

  5. Electric engine (in light aircraft under research).

Here I am not going to explain none of the above because if you are students you will learn more in your institutes but if you are not students this is enough for you. Now I shall tell you the story of my knowledge of Helicopter.

It was August 1971. I was posted to PAF Sargodha after my Basic training in SOA, PAF Korangi creek. There manning control send me to rescue squadron. In that squadron I had work in the KAMAN H-43 B Helicopter where I was given a familiarization course of the helicopter. In PAF and all Air forces to work in a certain aircraft unit used to give above course. I am having interesting story of getting chance in a cross country flight over Sargodha by that Helicopter. Other interesting event was Group Captain Thappa (most probably Golam Haider, if I am not forgotten) was doing flying training in that aircraft. Thappa might be his family name or name given by the airmen of PAF base Sargodha. Its cause was he was very discipline minded Base commander. He was interested make each one of his base disciplined like him. While he saw even from his flag car someone in shabby dress or outsmarts movement he stopped and checked. Once it happened with me also. Once in my duty time due to some reason I was walking by the way of Fighter F-104 squadron. Suddenly they flag car stopped by me and from the car someone called me. I ran hastily, I was in proper attention position before him. So, he was in laughing mood. I answered his questions also in smiling face. Suddenly I heard a hard voice, “why are you laughing?” I answered in low voice, “as you are laughing, sir!” I heard another voice, “my face is like this!” The car left the place. However he did not put me on charge. Later I discussed the matter in the barrack, one of my roommates told, “Usko shekol aisha hai.”(His face is like this).

During the solo flight of the Base commander his landing was not accurate. So, he landed over the tail boom of the Helicopter. Its result was tail boom made by glass fiber broke. For practice flying for such big man like him ‘Saat khoon maph’ i.e everything was excuse. We the technicians ran to replace Brocken booms. This is the story of my working in the Helicopter. But story of my teaching of Helicopter is as follows. In Bangladesh ‘Aeronautical Institute of Bangladesh’ (AIB) is only Institute of this kind that is CAAB approved. In my retired life I am a full time writer in a project of Dr. Shah Abdur Rahim of Bangladesh Open University. Principal of AIB knew my back ground of aeronautical teaching. In May 2014, there was a Helicopter course. As I often visit there, its Principal Engineer Akmol Hossain told, “if you can take Tandem Helicopter and Helicopter vibration class I may allow you to take a class.” “Take preparation I will be in your class.” Accordingly I took preparation. I know such chance to take class is limited in Bangladesh. So, to inform you about Helicopter I added following few lines:

We knew that Helicopter is a type of an aircraft. It flies by the aerodynamic reaction of its rotor blades. Other factors are also there. Zones of Helicopter are as follows:

  1. Main Rotor Hub and blade assembly.

  2. Tail Rotor Hub and blade assembly.

  3. Forward top deck.

  4. Power plant.

  5. Aft top deck.

  6. Tail boom.

  7. Cabin interior.

  8. Forward Fuselage.

  9. Aft Fuselage.

  10. Landing gear.

According to rotor arrangements Helicopters are as follows:

  1. Single rotor helicopter (have a main rotor and a tail rotor).

  2. Counter rotating rotor crafts.

Counter rotating rotor crafts are as follows:

  1. Tandem rotors: Have two rotors one mounted behind of the other.

  2. Co-axial rotors: Have two rotors mounted one above the other on the same axis.

  3. Intermeshing rotors: Have two rotors mounted close to each other at a sufficient angle to let the rotor intermesh over the top of the helicopter.

  4. Transverse rotors: It is seen in the tilt rotor. Some early types helicopters used it. In this type a pair of rotor is mounted at each end of a wing type structure or the outrigger.

Helicopter is very complex types of aircraft. For its flight not only rotors movements but also its Disc loadings (ratio of the weight to the total main rotor disc area, and is determined by dividing the total helicopter weight by the helicopter disc area.) , Coriolis effect (the tendency of rotor blade to increase or decrease its velocity in its plane of rotation when the center of mass moves closure or further from the axis of rotation, Torque effect, Gyroscopic precession (an inherent quality of rotating bodies, which causes an applied force to be manifested 90 degrees in the direction of rotation from the point where the force is applied.), Settling with power (is condition of power flight where the helicopter settles into its own downwash. The condition may also be referred to as a vortex ring state), various loads like other aircrafts etc to be considered. Said loads are as follows:

  1. Stress.

  2. Compression.

  3. Twisting/ Torsion.

  4. Shear.

  5. Bending.

  6. Hoop stress.

  7. Metal fatigue.

For the beginners above is enough. When you as new students will start learning or impart lesson of the subject as a teacher you will have to know more. But I like to tell something about Vibration. It is shiver of any body. In case of Helicopter it is shiver to complete helicopter for which accident may also occur even. Vibration i.e. bouncing of the helicopter up and down is caused by a blade when that is out of track. In helicopter vertical vibration i.e. movement up and down or vertical is experienced time to time. So, when you will have chance to learn more you will have to know about Blades i.e. every characteristics of its parts as Blade Tip, Blade Track, Blade Tracking, Blade Twist, Blade Coning, Blade Feathering, Blade Flap, Blade Grip, Blade lead or lag etc everything. Wish the best.

Long ago I left the defense force. Now I am an old man. I will be happy if above story help you.