SAFETY FEATURES
Safety Overview
All flying, whether a commercial 747 flight or a recreational parachute jump, entails a degree of risk, gravity can be unforgiving. Aviation users, passengers and pilots alike are aware of this risk and make personal decisions on the degree of risk they accept for themselves. For most of us this means that a commercial aircraft flight is an acceptable risk whereas a parachute jump may not be. For some even a parachute jump is boring and higher risk is desired!
All aircraft designers hold safety as a paramount concern. Safety has a number of layers. Safety starts with the concept stage where consideration of reducing risk is integrated into the design. Safety then flows into the engineering design and calculations where levels of risk and "factors of safety" are calculated. The manufacture and quality assurance are the next layer in the design process. Testing the design is where the theory is validated.
After manufacture the "human factors" come into play. These include standard operating procedures, training and retraining of the end users to maintain a high degree of compliance.
At all times each step in the process is open to further improvement.
Safety features:
Roll cage
Although it is not visually apparent the Martin Jetpack has an internal roll cage. The ducts currently have a carbon kevlar hoop. These are to protect the pilot from side impact. The control arms protect from the front and are designed to snap off in a hard impact, the ducts then further protect the pilot. The structure extends below the level of the spine to prevent injury from a hard landing. In effect the pilot is housed in a protective cocoon by the structure and engine. Further enhancements are planned for impact protection, the goal is to provide impact protection from 30 feet high.
Mechanics
The Martin Jetpack has a number of mechanical things moving fast....a drivetrain, FanJets. All these are designed with far higher "factors of safety" (FOS) than is normal for an aircraft. This was done because of the newness of the design and to cover for unforeseen factors. For instance the Fan blades have a FOS of 5, at the hub and over 10 at the blade.
Parachute
Production versions of the Jetpack are equipped with a Ballistic Parachute system from Ballistic Recovery Systems. This enables the pilot to be saved from a catastrophic failure down to a reasonably low altitude. Ballistic parachutes can open at very low altitudes, particularly if the aircraft has some forward speed. For this reason the "flight profiles" will be calculated to have the lowest risk possible.
But how safe is it?
Minimal Avoidance Curve
Helicopters and other VTOL aircraft normally have an avoidance curve. This is
the height where an impact is not survivable but below which other procedures like "autorotation" are not possible. Currently we think that with good design and correct flying procedures the avoidance curve can be eliminated. This is one of the reasons we feel that the Jetpack will be safer than current "light helicopters".
No tail rotor
An analysis of Helicopter accidents indicates that hitting the tail rotor into
an object and/or having a tail rotor failure is a significant cause of crashes.
Additionally walking into the tail rotor or main rotor is a safety concern for bystanders. The Jetpack was designed from the outset to be "torque neutral" thus no tail rotor is needed.
No rotor strikes
One cause of helicopter accidents is their main rotors coming into contact with objects like a wire. The Jetpack ducts protect the rotors. Additionally, when on the ground, the ducts provide enhanced safety for other people.
High Safety Margin
In a helicopter the articulated head and tail rotor gearbox are required to be a very high specification design using the best materials and requiring frequent and costly maintenance. The frequency and high cost of this has led to reluctance by some operators to have this maintenance done at the required frequency. Several accidents have been traced to this cause. The Jetpack has none of these components. Due to the design of the Jetpack it is possible to have a very high factor of safety in the rotating parts without significant weight penalty.