The Theory Of Helicopter Flight
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wah this is my second bad news I heard today...Originally posted by eurofighter:Anyway I heard an SP flying over my house today and think it was on the news that some SAF soldiers were injured. Somehow I dread hearing it cos it will mean a medevac is being carried out. All those major accidents like the CSC incident, I heard it flying to SGH.
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Firstly check for pressure and expiry date.Originally posted by eurofighter:Oh so that green thing is the bcf extinguisher. Can tell me how you use it and wats it for
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there's a safety pip pin, remove it.
and turn handle (there's fuse wire around it) on, can start using liao... -
must have one next to the aircraft when it is parked.Originally posted by eurofighter:Oh so that green thing is the bcf extinguisher. Can tell me how you use it and wats it for ?
i don't think anyone wants to use it!!! Anyway a starter crew has 2 people, one is the fireguard (the person with the extinguisher), the other is the marshaller.
So at every startup we look at the engine. Should there be any prolonged fire coming out from the engine, the marshaller will do the "Fire" signal to the pilot who will shut down the engine. The fireguard meanwhile will spray into the air intakes for a few seconds. If it is still on fire, the fireguard will spray into the exhaust.
Should there be a fire coming from the MGB (Main Gear Box), we will plug the end of the extinguisher into the fire access panel on the left side of the aircraft. Look at the first picture, see the exhaust and behind that there's a dotted circle, that's the fire access panel.
BCF is corrosive, so using it in the air intake will cause some damage, but using it in the exhaust and the engine is finished. In SBAB, only 125 is using BCF extinguishers now.
Why does the extinguisher have such a long handle? Because we're too short that's why!!! Its for reach, but you gotta protect your hand if you're holding onto that, its gonna be freezing and your palm might get stuck on it, so we use rags. -
I hate fire fighting lessons and refresher courses... always the same tv program played over and over again, the same ang moh, the same fires...Originally posted by OrneryBoy:Firstly check for pressure and expiry date.
there's a safety pip pin, remove it.
and turn handle (there's fuse wire around it) on, can start using liao...
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but one thing BCF is outdated, carbon dioxide would be recommended to use, since BCF is corrosive and hard to remove chemical.
Video? I watched twice so far... usually the best time to doze off...
my pre-NS secondary appointment is Safety..
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I have no idea why only 125 is the remaining squadron to use BCF, and it doesn't look close to changing. Gotta ask Fire I/C one day...Originally posted by OrneryBoy:but one thing BCF is outdated, carbon dioxide would be recommended to use, since BCF is corrosive and hard to remove chemical.
Video? I watched twice so far... usually the best time to doze off...
my pre-NS secondary appointment is Safety.. 
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ask ur seniors... ur WO may know?Originally posted by kopiosatu:I have no idea why only 125 is the remaining squadron to use BCF, and it doesn't look close to changing. Gotta ask Fire I/C one day... 
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Just some extra info about a system we have on the aircraft.
The EuroHUMS™ a second generation system was developed specifically for Eurocopter based upon the core Health functions within the North Sea HUMS. This system is designed to be interchangeable between the Mk I and Mk II Super Puma where it is an integral part of the aircraft essential system airworthiness certification. It is now in operation with six different operators, both military and civil, within Europe, the Far East and Australia.
Benefits of HUMS
- Alerting maintenance personnel to drive train health
- Alerting maintenance personnel to exceedances
- Eliminate dedicated RTB flights
- Reduce non revenue flights
- Reduce inspections and false removals
- Insurance savings
- Improved avionics life through reduced airframe vibration levels
System Components (Airborne)
- HUMS data acquisition and processing unit
- Pilot interface and display panel
- Rotor blade tracker, day and night-time operation
- Accelerometers and tachometers
- Cockpit voice and flight data recorder and FDR sensors
Functions
- Rotor track and balance
- Transmission vibration monitoring
- Shaft balance
- Gearbox (Main, Tail and Intermediate) diagnostics
- Rolling element bearing diagnostics
- Broad band vibration analysis
- Engine vibration monitoring
- Engine power assurance monitoring
- Chip detector monitoring
- Usage monitoring
- Flight manual exceedance recording
- Status of aircraft health after each flight
System Components (Ground Support Equipment)
- Hums information management
- Data retrieval unit or memory cards -
What is HUMS???
Stewart Hughes is universally recognized as the company that set the world standard in Health and Usage Monitoring (HUM) systems design. The first certified integrated Flight Data Recorder/HUM system was launched in 1991. Stewart Hughes designed the HUM to meet the North Sea operators' requirements and ensure maximum levels of safety in one of the world's most hostile environments. This system is approved by the CAA Aircraft Directive HUMS and includes a Cockpit Voice and Flight data Recorder system that is fully compatible with ED55/ED56A specifications
The whole of the aircraft dynamic system is monitored throughout the flight, with the results of the analysis being stored for many flights. When combined with the widest range of proven HUM monitoring techniques available these pioneering systems have proven to be affordable and effective in operation. Stewart Hughes' technology delivers a high probability of success with a low false alarm rate.
For these reasons Stewart Hughes systems lead the market in both retrofit and new build aircraft, with over 250 systems in service and 500 000 flight hours of data collected.
A number of potential accidents and incidents have been prevented by the use of Stewart Hughes' HUM systems. The CAA's monitoring of the performance of HUM systems has shown that helicopter safety levels have improved. Operators are also now benefiting from the technology such as the Stewart Hughes track and balance technology, also implemented in the Rotor Analysis and Diagnostic System, RADS-AT, and are beginning to reap the benefits of maintenance credits in terms of reduced direct operating costs.
HUM systems have revolutionized helicopter maintenance. They give an unparalleled range of information to the operator's maintenance team. Stewart Hughes has the largest team of support engineers in the industry fully experienced in interpreting HUM data. The full range of training and logistic support is available.
Technical Support to the operator's line engineers on HUM data interpretations is a service that is also available in the Stewart Hughes support package ensuring that HUM data is effectively used. Stewart Hughes designed HUM systems dominate the market for both military and civil system and the company has proven to be capable of adapting to the differing operational demands.
Stewart Hughes customers include. Helikopter Service Group, Canadian Helicopter/Skotia, PHI, Air Logistics/Bristow, ERA/KLM. Canadian Forces, Republic of Singapore Air Force, and the Royal Netherlands Air Force. Technology is evolving rapidly and Stewart Hughes is maintaining its position in HUM system development. Stewart Hughes is now supplying third generation HUM systems. The Stewart Hughes design teams accumulated experience in both the novel hardware and software technologies for the airborne and ground station components of the system extends over 15 years.
When implementing a new HUM system in either a retrofit or new aircraft application, this level of experience ensures the customer the lowest cost and lowest risk route. This is why Bell, Boeing and Eurocopter have all selected Stewart Hughes as part of their HUM system development activities.
New technology is being developed for the third generation of systems. This includes using HUM data to assist the pilot in avoiding exceedences, direct loads on components and engine distress monitoring systems.
This generation of system will find application on a wider range of aircraft including light single an twin helicopters. This continued development in HUM technology will ensure that Stewart Hughes maintains its leadership in the field. -
Kopi... too much information.
So detail on the HUMS system ar. -
wah sibei chim sial....
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hahaha eh, its what i got on the Web leh... the HUMS company! Heng heng found it also...Originally posted by X-men:Kopi... too much information.
So detail on the HUMS system ar.
Eh guess what, i am the new suay kia in the squadron -
what is suay kia?Originally posted by kopiosatu:hahaha eh, its what i got on the Web leh... the HUMS company! Heng heng found it also...
Eh guess what, i am the new suay kia in the squadron -
means everything i touch is suay.Originally posted by X-men:what is suay kia?
i've got a list of things...
engine mag plug pop out during hover.
hoist hydraulic leak during SAR ground run.
GPU unable to couple during normal check.
Aircraft P1 landing.
HUMS error during downloading. -
hahaha....Originally posted by kopiosatu:means everything i touch is suay.
i've got a list of things...
engine mag plug pop out during hover.
hoist hydraulic leak during SAR ground run.
GPU unable to couple during normal check.
Aircraft P1 landing.
HUMS error during downloading.
I dont care.. by next july make sure you clear this suay sh|t or u dont touch the aircraft I'm on -
Hahahaha you will be on, but you'll land next to tower. Muahahahahahaha~Originally posted by X-men:hahaha....
I dont care.. by next july make sure you clear this suay sh|t or u dont touch the aircraft I'm on
Oh recently got another P1 landing. Landing gear failed to extend, it was a long route nav sortie.
I was doing secondary appointment that day, but if I were servicing, it would be that aircraft -
you really need to go find seven different coloured flowers and batheOriginally posted by kopiosatu:Hahahaha you will be on, but you'll land next to tower. Muahahahahahaha~
Oh recently got another P1 landing. Landing gear failed to extend, it was a long route nav sortie.
I was doing secondary appointment that day, but if I were servicing, it would be that aircraft
remember the flowers cannot be those with thorns... like roses.
go bathe... -
my colleagues ask me to go buy bird leh, then when it turns into a chicken i must inform themOriginally posted by X-men:you really need to go find seven different coloured flowers and bathe
remember the flowers cannot be those with thorns... like roses.
go bathe... -
ever tools unaccounted? all flights cx, looking for a single tool...
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have, ratchet disappeared then appeared one week later... amazing.Originally posted by OrneryBoy:ever tools unaccounted? all flights cx, looking for a single tool...
Somemore it happened during the day we had to support a major exercise.
Stay back from 8am-8pm. -
Hey hey, i've got another set of QnA...~~~~
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Question: Can you please explain how a helicopter moves forward? The blades of the helicopter rotate around the vertical axis, so it generates a vertical lift force. Then how do you get forward motion?
Answer: To answer this question, we need to take a more detailed look at the mechanics of a helicopter rotor and define a few new terms for discussing the rotor. As a helicopter rotor is rotating about its vertical axis, the blades are constantly changing, not only in location, but also in pitch, and more importantly in angle with respect to the vertical axis. It is this variation in angle that gives the helicopter a forward motion. Each of these changes to the blades happens in turn, so let's look at each one in more detail.
The blade's change in location is the most obvious. As the blade rotates around the vertical axis, its location is changing. At one point in time, the blade will be aligned with the nose of the helicopter, and a tenth of a second later, that same blade will be aligned with the tail.
As the blades rotate, their pitch, which is defined as the rotation of the blade along its length, is constantly changing. There are two different types of these changes in pitch, and they are both the result of pilot inputs. The two different types of blade pitch changes are "collective" and "cyclic," and they share their names with the pilot controls used to control them. When a pilot wants to go up or down, he or she uses the "collective," which is mounted to the left of the seat. This control collectively changes the pitch of all the blades the same amount, increasing or decreasing the total lift of the rotor, and causing the aircraft to climb or descend. When a pilot wants to move forward, backward, or to the side, he or she uses the "cyclic" which is usually mounted between the legs. This control cyclically changes the pitch of the blades as they rotate. Let's consider the pilot wants to fly forward. He or she would then push the cyclic forward, which would cause the rotor blades to increase in pitch as they approach the rear of the helicopter, increasing lift in that area. If the pilot uses enough cyclic control, this can cause the entire helicopter to tilt forward, allowing the rotor to pull the helicopter through the air. This is often seen in war movies, since it is the best way to get going quickly, since a large portion of the rotor's thrust is pulling the helicopter forward. Believe it or not though, a helicopter can remain perfectly level and still move forward, backward or sideways, with the help of "flapping hinges."
Most people don't realize how complex a modern helicopter rotor really is. Along with the collective and cyclic controls, there are also various hinges, which allow the blades to move in different directions. The ones we are concerned with here are the "flapping hinges," which actually allow the blades to "flap" up and down as they rotate. The centrifugal force of the rotating blades keeps them from flapping out of control. Since the blades are free to move up and down like this, aerodynamicists use the term "tip path plane," (or TPP) which is defined as the flat plane that the tips of the blades create as they rotate. When a pilot inputs forward cyclic, this causes the blades at the rear of the helicopter to flap upwards, which causes the TPP to tilt forward. This forward tilt to the TPP then causes the helicopter to move forward. The illustration below shows the TPP for a helicopter both in hover (blue TPP) and forward flight (orange TPP).
Comparison of the tip path plane of a helicopter rotor in hover (blue) and forward flight (orange)
In short, a helicopter is a very complex system, but these complexities are necessary for the helicopter to fly, let alone maneuver. In order to fly in any given direction, it is necessary to develop a thrust in that direction, either by tilting the entire helicopter, or simply by tilting the TPP.
If nothing else, this long explanation of one part of a helicopter's flight envelope shows how complex helicopters really are. If they didn't possess such significant advantages over fixed wing aircraft, one might wonder if they ever would've been as popular as they are now! -
Question: I have seen helicopters on TV shows that only had ONE main rotor and NO tail rotor, so how do they work?
Answer: As you may know, yaw is the ability of a vehicle to rotate from left to right. In previous answers concerning the yaw control of helicopters (#1 and #2), we discussed how a tail rotor is used to maintain yaw control and counteract the torque effect. Since that time, we have received several more questions regarding how helicopters without tail rotors maintain yaw control. Hopefully this week's answer will help clear up some of the confusion.
To fully understand the purpose of tail rotors and helicopter yaw control, we must go back in time to the 1600s when Sir Isaac Newton developed his laws of motion. Newton's third law of motion, in its popular form, says that "Every action has an equal and opposite reaction." Keeping this in mind, think of a typical helicopter with a single rotor. As the rotor spins clockwise at a high rate of speed, there is an equal and opposite reaction acting on the helicopter fuselage making it want to spin counterclockwise. To keep the helicopter from becoming a flying pinwheel, we must somehow exert a force on the fuselage to counteract that of the main rotor. Notice that I haven't said anything about tail rotors yet. In fact, if a helicopter were to be flying forward fast enough, a vertical tail like that used on an airplane would provide enough force to counteract the torque of the main rotor, without any tail rotor! In fact, this mode of flight is actually one of the emergency procedures recommended when a tail rotor malfunctions. Of course, one of the reasons helicopters were developed in the first place was the desire to hover over one spot with no forward velocity. This requirement then brings us back to the need for some kind of force to counteract that of the main rotor.
Depending on who you ask and how you count, there are four different ways to counteract the force of the main rotor: a tail rotor, twin non-coaxial rotors (either tandem, side-by-side, or intermeshing), twin coaxial rotors, and the NOTAR system. We believe that NOTAR is the particular method you are referring to in your question, but let us explore each of these options for the sake of completeness.
Tail Rotor:
Tail rotor configuration
By far the most common method for yaw control was first used by Igor Sikorsky in 1941. Sikorsky's configuration featured a single main rotor with a small tail rotor mounted at the end of a long tail boom, as exemplified by the AH-64 Apache. While the main rotor generates the lift and thrust that make flight possible, the purpose of the tail rotor is to counteract the torque effect. The tail rotor works much like any propeller or rotor. It spins at a high rate of speed, accelerating air in a specific direction, to create a force in the opposite direction that counteracts the force of the main rotor. The pilot of the helicopter can alter the properties of the tail rotor to increase or decrease this force thereby causing the helicopter to yaw to either the left or the right. To maximize the force of the tail rotor, the rotor is usually mounted on a considerably long tail boom. There are two notable disadvantages of this arrangement. First, the long tail boom creates an aircraft with a large "footprint," meaning it needs more space for maneuvering and storage. Second, while the helicopter is on the ground, the spinning tail rotor is usually low to the ground so that it presents a hazard, often a fatal one, to ground crew.
Keep in mind that this approach is only ONE way to counteract the torque effect, and while it is the most common, it is generally considered the most complex! Just like a car isn't the only way to get around town (I personally use a human-powered spring, aka a pogo stick), the tail rotor isn't the only way to counteract the torque of a helicopter rotor. -
Twin Non-Coaxial:
Twin non-coaxial rotor configurations, tandem rotors and side-by-side rotors
If you are going to build a large helicopter for lifting heavy loads, then it makes sense to use two separate rotors to generate more lifting force. If these rotors are separate, such as those on the CH-46 Sea Knight or the V-22 Osprey, then they are called "non-coaxial," meaning they do not share the same axis. Since these helicopters have two rotors that are usually equal in size, the simple solution to the yaw control problem is to spin the rotors in opposite directions. Thus, the yaw forces created by each rotor cancel each other out. Yaw control is achieved by tilting the rotors in opposite directions (to the left and right in the case of the CH-46).
Twin non-coaxial rotor configurations, intermeshing rotors
A subgroup of twin non-coaxial rotors is the twin intermeshing rotor system, seen only on a few helicopters made by the Kaman company, including the H-43 Husky and K-MAX. The principles by which intermeshing rotors operate are the same as those previously discussed for other twin rotor helicopters. The difference is that the rotors are mounted very close together and actually intermesh, i.e. the blades on one rotor travel through the rotor disk of the other rotor. Of course, the intermeshing of the rotors is carefully timed to keep the rotors from chopping each other to pieces. There aren't many flyable H-43s left, but when they are airborne, they are indeed an interesting sight. -
Twin Coaxial:
Twin coaxial rotor configuration
Another yaw control strategy pioneered by the Russian manufacturer Kamov utilizes two rotors that share the same axis (coaxial), an example being the Ka-50. Much like the non-coaxial design, the rotors rotate in opposite directions, each one counteracting the yaw force of the other. Yaw control is achieved by increasing the blade pitch on one rotor while decreasing the pitch on the other. The result is a differential in torque, resulting in a yawing motion. The most notable advantage of the twin coaxial arrangement is that it is very compact. Although the twin rotor configuration tends to be rather tall, the lack of a long tail boom results in a very short fuselage that takes up much less space. For this reason, Kamov designs have proven very popular for shipboard use with the Russian Navy.