A tip jet helicopter also called the ramjet uses nozzles at the tip of helicopter rotor blades to spin the rotor.
Source: Travel for Aircraft
In a tip jet helicopter, the conventional shaft drive is replaced by the tip jets which eliminate the need for using a tail rotor. Other advantages of a tip jet include improved stability and reduced vibrations.
For instance, ‘The Hornet’ was a tip jet helicopter that got rid of expensive engines, tail rotors, multiple instrument panels and gearboxes like the conventional helicopters. It relied completely on two jets mounted on the tips of rotor blades for propulsion.
Source: Advanced Technologies
If a tip jet helicopter has so many advantages, why is the technique not commonly used? The answer lies in the fact that even with all the perks, its benefits are outweighed by its drawbacks. The tip jet as compared to other helicopters requires little maintenance but has a noisy interior and covers a very short-range. While noise is a significant problem, it isn’t the only one. The tip jets are not very efficient. The spinning mass causes strong gyroscopic tendencies in two axes hence, reducing the efficiency.
Moreover, there exists a problem of feeding fuel into moving rotor wings and synchronizing the thrust of the engines. Another issue that arises with a tip jet is how the rotor blade angle will be varied without deranging the motor orientation.
Source: Aerospace Web
The current helicopter technology eliminates the problems posed by the tip jet. It may have its drawbacks, but at the minimum, it will save you from the ramjet noise driving you deaf.
Which of the two technologies would you prefer? Comment below!