The Avro engineers weren't only concerned with the Mark 1 and 2 Arrows. They were also making plans for the future. As it's been said before best estimates for top speed of the Arrow were around mach 2.3 or 2.4.Plans were made to increase the Mark 2's speed to Mach 2.5. Also plans were being made for areconnaissance Arrow, trainer Arrow, and intermediate bomber Arrow.The most intriguing of the engineers plans, however, is that of the ultimate Arrow.
Specs
The ultimate Arrow would have a range in the 1,000 n.m (nautical mile) region, would operate at60,000 feet, and have a top speed of mach 3. I don't believe there was anyplane at that time that was anywhere near this kind of performance.
Design Differences
The most obvious difference between the Mark 2 Arrow and the Mark 3 or ultimate Arrow are the revised engine intakes. These can be seen below.
Engine plans consisted of using a developed version of the Iroquois with variable engine intakes.Other design changes may have included wing fuel pods, revised landing gear to make room for thesepods, and the use of ZELL or Zero Length Launch.
Weapon System
Planning weapon systems was never Avro's strongest suit. Best estimates, however, indicate thatthey would need something with very long range. This would require a powerful rocket and probably would include nuclear warhead capability. The rocket would also have to be able to manoeuver on its own. The final weapon spec would call for the the rocket to climb to 15 or 20,000feet about the aircrafts 60,000 foot ceiling.
