Despite all the efforts of engineers, the first jetpacks and other personal aircraft from Bell Aerosystes had one major flaw. The transported fuel supply (hydrogen peroxide) made it possible to stay in the air for no more than 20-30 seconds. Thus, all the company's developments were of great interest to specialists and the general public, but had no real prospects. Nevertheless, Wendell Moore's team still managed to create a jetpack with a long flight duration. The Bell Jet Belt was able to fly for over 20 minutes.
Experiments over several years have shown that hydrogen peroxide engines cannot be used in full-fledged jetpacks. Such engines had a simple design, but they were not at all economical. For example, the engine of one of the Bell devices consumed 7 gallons (about 27 liters) of fuel in just 30 seconds. This meant that the only way to increase the flight duration was to use a different engine. The development of a new project using a new power plant started in 1965.
After a couple of failures, W. Moore was able to convince representatives of the military department of the prospects for his new project. This time it was proposed to build a jetpack based on a turbojet engine. Such an engine differed from the existing ones, running on hydrogen peroxide, in much greater fuel efficiency and made it possible to count on high performance.
Jet Belt in flight. Photo Rocketbelt.nl
The Pentagon experts agreed with the arguments of the representatives of Bell Aerosystems and opened funding for a new project. A promising jetpack with a new engine was named the Bell Jet Belt. Apparently, the name was chosen by analogy with one of the previous projects, Rocket Belt.
The main element of the new aircraft was to be a turbojet engine with a number of specific features. It was required to create an engine of small size and weight, having acceptable traction and fuel consumption. Moore's team turned to Williams Research Corporation for help in creating the engine. This organization had some experience in creating turbojet engines, which was planned to be used in a new project.
The result of the work of experts from Williams Research Corp. under the direction of John C. Halbert, the WR19 by-pass turbojet engine was introduced. The requirements of the project colleagues were quite high, in addition, technological difficulties affected the course of work.
Halbert's team was ordered a minimum-size by-pass turbojet engine. The use of a two-circuit design was associated with the intended application of the engine. The fact is that the mixing of hot reactive gases from the internal circuit with cold air of the low pressure circuit led to some cooling of the jet stream. This feature of the engine made it less dangerous for the pilot. Considering the general architecture of the Jet Belt, it can be considered that this was the only suitable powerplant option.
Development of the WR19 engine continued for several years, which is why the assembly of an experienced jetpack started only at the end of 1968. The new engine weighed only 31 kg and developed thrust up to 1900 N (about 195 kgf). Thus, the WR19 product could without any problems lift itself into the air, other equipment of the knapsack and the pilot, including, possibly, with a small additional payload.
The Bell Jet Belt jetpack was developed using some of the developments from previous projects, but using a new engine and other units. The basis of the design was a support frame with a corset and a belt system that redistributes the weight of the backpack onto the pilot's body while on the ground and vice versa during the flight. An engine was mounted on the back of the frame, on the sides of which there were two fuel tanks. Above the engine there was a nozzle block, the units of which were proposed to be used for maneuvering.
A bypass turbojet engine was placed with the air intake down. To protect against various objects that may enter the engine, the air intake was equipped with a mesh filter. The engine nozzle was at the top, at the level of the pilot's head. There was also a special nozzle block, the design of which was probably created taking into account the developments on old engines running on hydrogen peroxide.
Williams WR19 engine. Photo Wikimedia Commons
The jet gases of the engine were split into two streams and directed into two curved pipes with nozzles at the ends. The nozzle apparatus brought out two jets down, on the sides of the pilot. Thus, in terms of overall layout, the new Jet Belt was almost indistinguishable from the old Rocket Belt. To control the thrust vector, the nozzles were mounted on hinges and could swing in two planes.
The control system was borrowed, with some changes, from the previous Bell experimental devices. Two levers were connected with movable nozzles, which were brought forward, under the pilot's hands. In addition, for greater rigidity of the structure, a pair of struts were added to the levers. On the remote parts of the levers were located control knobs, with which the pilot could adjust the thrust and other parameters of the engine. Using the right handle, the engine thrust was changed. The left handle made it possible to turn to the right or left with the help of special devices on the nozzles. Synchronous tilt of the levers forward or backward made it possible to make a forward flight in the desired direction.
According to some reports, the onboard equipment retained a timer to determine the duration of the flight and warn the pilot about fuel consumption. In addition, testers on the ground could monitor fuel consumption. For this, the tanks were made of transparent plastic. There were measuring scales on the walls.
Popular Science article on the Jet Belt project
Despite the use of a bypass engine, the temperature of the jet gases remained too high. Because of this, the pilot had to use protective coveralls and appropriate footwear. In addition, the safety of the head, organs of sight and hearing was ensured with the help of a soundproof helmet and glasses. The pilot's helmet was equipped with a headset connected to a radio for communication with the ground crew. The radio was carried in a belt pouch.
A landing parachute was installed on the top of the nozzle block. In view of the risks associated with the use of a turbojet engine, it was decided to equip the vehicle with rescue equipment. If necessary, the pilot could open the parachute and lower it to the ground. Nevertheless, the effective use of this tool was ensured only at heights of more than 20-22 m.
The assembly of the first experimental "Jet Belt" was completed only in the spring of 1969. Soon after that, test flights began in the hangar on a leash, as a result of which the device was released into free flight. On April 7, 69th at Niagara Falls airfield, test pilot Robert Courter first took the device into the air without safety equipment. During the first flight, the tester climbed to a height of about 7 meters and flew in a circle of about 100 meters. The maximum speed during this flight reached 45 km / h. It is noteworthy that during the first flight, the Bell Jet Belt product used up only a small part of the fuel poured into the tanks.
Bell jetpacks. Jet Belt on the left, Rocket Belt on the right. Photo Rocketbelts.americanrocketman.com
Over the next few weeks, the testers made a series of test flights. During the tests, the speed and duration of the flight were constantly increasing. Until the end of the tests, it was possible to achieve a flight duration of 5 minutes. Checks and calculations showed that at maximum fueling, the "Jet Belt" can remain in the air for up to 25 minutes, developing a speed of up to 135 km / h. Thus, the characteristics of the new personal aircraft made it possible to make plans for its use in practice.
At the end of 1968, Wendell Moore suffered a heart attack, the consequences of which later again made themselves felt. On May 29, 69, the engineer died, which actually put an end to all projects of promising aircraft. Moore's colleagues after his death made an attempt to complete the Jet Belt project and fulfill the terms of the contract with the military department. Soon the device was presented to the customer's representatives and received an official response.
Probably, the authors of the project doubted that their development in its current form could interest the military and would come to mass production in the interests of the army. The device turned out to be too heavy: about 60-70 kg with a full refueling. In addition, it was difficult to control and reacted to the movements of the levers with some delay. Difficulty landing with a heavy apparatus on the back was also noted.
Flying on the "Jet Belt" in the artist's view. Figure Davidszondy.com
Pentagon representatives reviewed the Bell Jet Belt product and recognized its superiority over other developments of the contractor company. However, this jetpack did not suit the military either. The customer's decision was affected by the identified design flaws, as well as its low survivability. In combat conditions, such a vehicle, which does not have any protection, could become an easy target for the enemy. No special means were required to destroy it. Even small arms could cause serious damage to a turbojet engine, after which it could not continue to work. In addition, the engine posed a danger to the pilot and people around him during an emergency landing. When the engine is deformed, the blades could come off with consequences similar to the result of a mine explosion.
The death of the creator and the failure of the military led to the termination of the Bell Jet Belt project. After the completion of the tests, the device was sent for storage, since it was no longer of interest to customers and company management. Moreover, the project and the whole direction have lost the main ideological inspirer and leader. Without W. Moore, no one wanted to pursue a promising but difficult direction. As a result, all work on personal aircraft stopped.
By the spring of 1969, only one Jet Belt was built, which was later used in short trials. After the closure of the direction, the device and documentation on it, as well as the documents of previous projects, were stored by Bell, but were soon sold. In 1970, all drawings and papers for all projects in this direction were sold out. In addition, some prototype vehicles have changed owners. Thus, the experienced "Jet Belt" and all related documents were sold to Williams Research Corp. The design documentation was later used in some new projects, and the only prototype of the Jet Belt soon became a museum piece and retains this status to this day.
