The easiest way to build a JetExec is to buy a Rotorway, the turbine and then K.I.S.S. conversion kit.  It is a relatively proven design and has good backup.  The conversion takes almost as long as the original build but it is worth it.  There are a few still a few areas that could be optimised in the available kits so we thought we would go for a bespoke design...

The following notes show some of the components that I would like to be optimised in the redesign:

• The power to weight of the standard Rotorway is not brilliant so every effort will be made to reduce the weight to a reasonable level.  The standard weight of the 162 Exec is over 410kg - that is not far off the weight of a 278hp Hughes 500C at 493kg!   By comparison a basic early R22 weighed 361kg...  The Alpi Syton / EH101 is 290kg!
• Turbine engine installation (for safety and power / weight reasons).  There are two trains of thought on whether the engine should be mounted high or low.  Each location has its advantages and disadvantages but I am mounting it as high as I can in the low position i.e. just enough clearance for the tail rotor drive to pass over the motor.  A particle separator is to be added if possible.
• The rotor system will be standard except for control rods and not cables.  We are considering lengthening the rotor mast as well to help with CofG issues.  Another option is a R22 head and blades for improved control and lower maintenance but considering that the helicopter is new I won't look at this as an option until necessary.
• Main rotor gearbox is a billet planetary transmission that was custom designed by a well respected aviation engineer.  The drive has significant capacity with a calculated 2000hr gear life.  If there is going to be any extra weight in the machine the main rotor box isn't a bad place to have it!
• The primary drive reduction box is to be designed to match the main rotor box.  It is a total custom design to suit this project and will incorporate a accessory drive for the alternator and a custom made oil cooling pump for the gearboxes.  A high capacity (950ft-lb!) carbon - carbon clutch will engage the rotors.  It is light (1.9kg) and its failure mode is to keep the drive connected.  The only downside is that it is not cheap!
• The tail rotor drive has increased capacity from larger custom taper lock pulleys and belts driven off the main rotor box.  The tail rotor spins at 2850rpm (faster) in the reverse direction to the Rotorway.  The sprag clutch is incorporated into the input of the tail rotor and main rotor gearbox coupling.  Even the standard belt drive is fine if it is maintained so I don't see the need to go to a shaft drive tail unless it proves otherwise.  I do have a KISS tail drive gearbox here though...
• The landing gear will sit the machine at a better landing angle and be made longer and 200mm wider to help prevent dynamic rollovers...  (The Rotorway has a much narrower track than a R22).  Basically the RHR leg is 45mm shorter with the rest interpolating.  The gear is also longer to maintain tail rotor clearance.  The longer skids are 4130 instead of aluminium and are designed to be more tolerant to hard, landings with forward speed...
• Stiffened tail boom.
• Custom fuel cell plus standard tanks for enough capacity a 2.5hr range. (that is a lot of fuel!).  The fuel cells will be have a flame proof coating.
• Carbon lightweight panels and a slightly different shape to suit the turbine better. 
• EFIS and data logging, FADEC turbine control including automated startup.
• Investigate the possibility of waterproofing the mechanical components better.
• Good access to components for maintenance.  The turbine and transmission will be able to be removed in less than 25 minutes with basic equipment.

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