Pilot Seat

Pilot seat design for our ultralight rotorcraft

Early in the history of helicopter flight, it became apparent that helicopter flight crews complained of a remarkably high incidence of back pain compared to their fixed wing counterparts. Over the past 25 years, the high incidence of back pain in helicopter flight crews has been documented in numerous reports. Most of these studies have reported prevalence rates in excess of 50 percent and many have reported prevalences exceeding 75 percent; apparently depending on the group studied. Based on this data, it has become clear that there are certain factors unique to helicopter flight operations that induce a high rate of back pain in crewmembers Seat comfort has become increasingly important in today’s society as we spend more time at consoles, instrument panels, or just online.

Pilot Seat
Pilot Seat design for experimental ultralight helicopter.

However, seat comfort is hard to define and difficult to measure. The amount of time spent sitting in uncomfortable and poorly designed seats coupled with inappropriate postures causes susceptibility to fatigue, lower back pain, and musculoskeletal disorders. The need for better seat designs that fit the target population and decreases biochemical problems and reduces fatigue is apparent. And recently, there has been a growing focus on the proper design of seat keeping in the view of user satisfaction including comfort, safety, and performance.

Placement

In general except for some helicopters, the right seat in the cockpit of an aircraft is the seatused by the co-pilot. The captain or pilot in command sits in the left seat, so that they can operate the throttles and other pedestal instruments with his right hand. However it does not matter in our case for one seater ultralight helicopter where seat is placed in center of cockpit.

Pilot seat placement for personal helicopter.

Comfort vs Discomfort

Protection foam patches.

According to Wikipedia, comfort is a state of physical ease and freedom from pain or constraint. Discomfort analogically is the opposite state. However, which factors contribute to discomfort is unknown.

For pilots, it has been suggested that inappropriate seat dimensions, improper sitting postures, poor physical conditions and stress levels are contributors to lower-back discomfort. Physical pain during flight can cause distractions and reduction in pilot performance, causing concerns in flight safety. Understanding how to prevent seat discomfort and thus biochemical issues is an investment in flight safety, as well as pilot comfort.

Postural Angles Analyses

Preferred sitting positions differ from person to person. However, these sitting positions may cause stress on the spine or be inappropriate for the task potentially leading to negative effects, such as musculoskeletal pain. To examine the variety and intensity of sitting postures under various seating conditions, postural angle analyses are important. One example is The Ovaco Working Posture Analysis System, which evaluates sitting postures that are preferred in a real-world setting. The system allows researchers to observe the frequency and duration in which each sitting posture occurs and later evaluate its appropriateness to the task.

The lower back sustains the most pressure when a human sits, stands, or lifts, making the lower back more prone to physical problems as a result. Seat designs must consider suitable sitting positions, while keeping job requirements in mind, to reduce lower back pain. An understanding of how the spine looks in a seated position, both good and bad postures is important.

An abnormal curvature of the spine while seated can have significant long-term effects on the vertebrae and muscles, causing discomfort and even infirmity. In a study evaluating the effects of assisted lordotic and kyphotic postures, where a lordotic spinal posture is preferred over a kyphotic sitting posture because it reduces and centralizes pain in the back and legs.

The posture that helicopter pilots must assume to fly is considerably different from that required to fly fixed wing aircraft. Helicopters require simultaneous input from all four extremities in order to maintain full control over the aircraft, and the types of missions flown seldom allow for relaxation from the controls. Furthermore, the seat and control configuration in most helicopters forces the pilot to assume an asymmetrical posture. It has been well documented that this control configuration forces pilots to bend forward in their seats and lean slightly to the left. This position does not permit relaxation of the spinal musculature and is a major source of discomfort for helicopter pilots.

Ergonomics

Ergonomic in product design.

The term ergonomics was proposed to British researchers by K.F.H Murrell in 1950. The first half, ergon, is Greek for work and effort. While, nomos refers to law or usage. Originally, ergonomics required understating of anatomy/physiology and experimental psychology.

Ergonomics is an important part of research in the product development process. Its purpose is to increase the safety, comfort and performance of a product or an environment, such as an office or helicopter pilot seat.

Additional fields such as sociology, anthropometrics, biomechanics, engineering science, and applied medicine now contribute to the use of ergonomics in the design of work systems, equipment design, human-computer interaction, industrial organization, and industrial engineering.


First Impressions

Don’t forget that this is also a product to sell. Ergonomics and aesthetics seem to mesh in the design of a product. However, there is a lack of research in the realm of comfort pertaining to aesthetics and first impressions. Those in marketing, manufacturing, and even advertisement have emphasized the importance of first impressions on aesthetics and attempted to understand their effects and how to apply that knowledge to the design and selling point of products.

Attempting to First Impression.

Materials

Constantly changing technology and providing new composite materials to use expect from designers constant exploration and use of new materials also in this area. For our small flyer I have chosen a carbon fiber reinforced polymer for seats profile, and also standard aerospace aluminum as a main materials for seat base, and with stainless steel for bolts materials. Please note that all photos showing item are only with pre-assigned materials or matcap. We will take care of the final finish in the later time.

Ejector Seat

In aircraft, an ejection seat is a system designed to rescue the pilot or other crew of an aircraft the seat is propelled out of the aircraft by an explosive charge or rocket motor, carrying the pilot with it. I am sure you heard about safety ejection seats for fixed wings aircraft pilots. With the first attempt by Everard Calthrop a inventor of the parachutes. He escaped from an aircraft with the a bungee-assisted. Later he patented an ejector seat using compressed air. But when it comes to helicopters things are getting complicated. Keyword are: space, weight, cost, reliability, and use constraints, injuries to the person.

Firstly, most of helicopters operate at lower altitude then fixed wings aircrafts what gives for example jet fighters pilots more time from ejection to open parashutes and hit the ground. Also considering the operating position of the helicopter in forward flight with a nose-down position at low altitude when ejecting forward will not give enough time to make this process safe. The side-way and down-words option usually have very tight use conditions and high failure rates. Upwords ejection has to take the spinning rotor over pilot head under the consideration. Ejection explosion must clear out the trajectory path from spinning blades and other parts. Another very important factor is weight. Some ejection seats can weigh over 90kg and require automatically more space.

Human resistance to G force

From 1946 through 1958, Colonel John Paul Stapp pioneered biodynamics investigations doing quantitative stress analysis of the human body to limits of voluntary tolerance of crash type impacts and deceleration.

  • Forward acceleration up to 20G is survivable.
  • Backward acceleration is much more taxing to the body.
  • Sideways acceleration has little influence on consciousness, but does have significant impact on supporting muscles for the head. So the head must be fixed in sideways position before ejection.
  • Upward acceleration is more taxing than in x- or y-direction, with problems occurring at 4-5 g depending on onset and duration. A typical Martin Baker seat creates accelerations of 12-14g but for a very short time.
  • Downward acceleration is tolerated the least well by the body.

The Kamov KA-50 it is the world’s first operational helicopter with a rescue ejection system. At first the blades are separated from the blade sleeves, which remain attached to the rotor hub, then a few fractions of a second later, the conventional upwards firing ejection seat is launched, using extraction rockets tied to cables to drag the seat clear of the airframe. In the aircraft, an ejection seat or ejector seat is a system designed to rescue the pilot or other crew of an aircraft in an emergency. In most designs, the seat is propelled out of the aircraft by an explosive charge or rocket motor, carrying the pilot with it. The concept of an ejectable escape crew capsule has also been tried. Once clear of the aircraft, the ejection seat deploys a parachute. 
The purpose of an ejection seat is pilot survival. The pilot typically experiences an acceleration of about 12–14g. 

Summary

For our project at this stage we need one low weight seat with safety belts and with adjustable base at x axis. No ejection system needed. The Seat base will be placed on 4 vibration dampers fitted to the airframe in the cockpit section. Materials used are aluminium and metal for seat base and reinforcements of back support, carbon fibre for seat profile, and also foam patches for protection, comfort and as a vibration damper. The 4 point belt system will keep pilot body in place during maneuvers. Images represent current state of my design. This chair prototype was tested with base third person hero from Unreal Engine 4 to make sure that pilot can reach all control devices without unnecessary stretch . Type male with height about 182cm tall .

This is the last part except the windscreen. Slowly, our prototype begins to resemble a helicopter. Now it’s time to focus on depleting geometry in unnecessary locations. Make corrections if necessary. Start preparation of uv maps and rigging of those parts that require it. Pre-ready parts I will import to “One Man Helicopter” project in Unreal Engine 4 to check the quality and I will start creating the final materials. Once all parts get done, then I will begin last stage for this update where I will modify existing code to adopt all new parts.

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