Bell, who had been exploring such designs throughout the 50s, had a promising lead with ducted fans. They had designed an aircraft called the D-190 sea-air-rescue utility aircraft for the Airforce, that could even be carried under the fuselage of a Lockheed C-130 Hercules.
Engineers discovered that a duel tandem ducted fan configuration allowed a shorter wingspan, and thus a lighter and smaller design to work. The tilt wing Vought XC-142A would win this contest, just beating the Bell and Lockheed D-2064, but the community was so impressed with the Bell Lockheed design that and they were given a $27 million contract, a quarter of a billion dollars today, to bring it life. Internally they called this version the exciting name of Model D2127, but was quickly dubbed the X-22 program.
The Bell X-22A had a somewhat boxy fuselage that was 39.7 feet long and a wingspan of 39 feet wide, although its front wing was only 23 feet wide, and came to around 20 feet tall. This smaller stature allowed it to fit within hangers and ships without any folding wings. As it was quick small, it only had a maximum take off weight of 8000 kg, or 17,600 pounds with its four GE turboshaft engines, producing 1267 house power, or 945 kilowatts each. Each of the propellers were 7 foot wide, or 2.13 meters.
These tilted ducked fans were the magic of the design. They would be able to rotate completely to allow the aircraft to lift from the ground vertically, then horizontally to allow the plane, if i can call it that, to fly horizontally at some speed.
These propellers would be able to take the aircraft up to a top speed of 221 kn (254 mph, 409 km/h), 387 nmi (445 mi, 716 km), so hardly the range or speed we commonly discuss on the channel, but compared to the range and speed of a typical helicopter today, the bell 206 long ranger, its around double the speed and comparatively the same range. It would have a service ceiling of around 27,800 feet, or 8,500 meters, meaning the cabin would require pressurization to keep the crew and passengers in comfort.
Bell fully intended for this design to be the beginnings of a whole new line up of military and civil aircraft. We know that there were at least 10 other variants proposed, and while we don't have information on them all, here is the highlight reel
- an enlarged development of X-22 for cargo operations with a rear ramp.
- a ducted fan large transport aircraft using the same fan configuration for marine deployment.
- ducted fan very large transport aircraft (also known as Model 2240) for military operations under fire.
- armed X-22A proposal, two trainable gun pods, an offset underside turret (looking not unlike the turret used on early Cobras) and a single deployable rocket pod.
- USAF Tactical Air Command VTOL aircraft, including a wholly new tandem cockpit and bombs that it could drop on enemy positions.
- Another version with guns but also a missile racks
- a special navy search and rescue version
- Apparently there was one that could also launch torpedoes, giving the Convair submersible plane video a run for its money.
So if it was so great... why was it never put into production?
In 1968, the x-22 was deemed most useful for the US navy, who then took over the project for further testing. and by further testing, i mean a good solid 15 years of tests.
The x-22a was always intended to be a test airframe, and had several design flaws.
For one, it never reached the top speed of 525 km/h, or 326 miles per hour, that the navy needed, although it came very close with the 504 km per hour in a test flight on a very windy day. This with the range and lifting capacity of the aircraft seemed weak, the navy couldn't really find a role for the aircraft. Especially that this prototype would require a 2nd design in actual production.
Also, it was rumored that the navy never really liked the design, preferring a competing Douglas model that never reached the prototype stage. So perhaps the powers that be simply decided to park the concept aircraft that landed on their plate.
Another issue with the design was noise. The small ducted fan like on the X-22 made a loud roar. Thus there would either need to be an upgraded stealth design, or the aircraft would not be suitable for combat roles - the enemy heard it coming.
With more funding and research required to make the x-22 work, the US military decided it had gone far enough, and that its learnings could be used for a totally new design, one that would slowly evolve into the V-22, which switched from ducted fans to tilting rotors.
