Hypersonic aircraft propulsion idea

[Junghalli]

I've been thinking a bit about different propulsion systems for aircraft and spacecraft and I came up with this idea. Please evaluate it for me.
Assume you have the technology to create a relatively small fusion reactor, something that could be fit inside an aircraft. You have an air intake, which leads to a conduit. The conduit goes around and through a spherical tokomak reactor, heating up the air to very high temperatures (and incidentally also functioning as part of the reactor's cooling system). The hot air is then passed out the back as a jet.
Would this work or does it stink? If it stinks can it be improved?

[Master of Ossus]

It would be incredibly sucky at high altitudes, where there is very little air for such a system to use.

[Junghalli]

It would be incredibly sucky at high altitudes, where there is very little air for such a system to use.

What if you combine it with the air intake system for a jet engine? They seem to work fine at high altitudes.

[Sea Skimmer]

I've been thinking a bit about different propulsion systems for aircraft and spacecraft and I came up with this idea. Please evaluate it for me.
Assume you have the technology to create a relatively small fusion reactor, something that could be fit inside an aircraft. You have an air intake, which leads to a conduit. The conduit goes around and through a spherical tokomak reactor, heating up the air to very high temperatures (and incidentally also functioning as part of the reactor's cooling system). The hot air is then passed out the back as a jet.
Would this work or does it stink? If it stinks can it be improved?

It works. It works so well that the US military basically beat you to the punch nearly 50 years ago with the PLUTO Supersonic Low Altitude Cruise Missile. PLUTO was powered by nuclear ramjet engine, using a 600MW fission reactor. This engine was test run twice, using a huge array of oil piping filled with compressed air to simulate the multi mach airflow it required. The missile would be so radioactive that its aircraft had to be coated with gold to avoid excessive metal from neutron bombardment.

PLUTO would have been launched from any point on earth from a trailer, using solid rocket boosters to reach supersonic speed where the ramjet would be started. It would then cruise at mach 4 to the target area, where it would drop down to 500 feet to make a mach 3 terrain following attack. The payload would be 15-26 thermonuclear bombs. The guidance system was TERCOM, and that technology (used later by Tomahawk cruise missiles) was invented for the program.

The weapon was more or less insane, because wherever it flew it would spew out radioactive fallout (the reactor slowly broke up) and it had to eventually crash somewhere. US planners however intended to have it keep flying for as long as possible after it had delivered its nukes, because the shockwave from a mach 3 missile at 500 feet would easily flatten buildings.

If you had a fusion reactor with a sufficiently high power output, then that wouldn’t be an issue and you’d have an incredibly powerful weapon. The US canalled Pluto mainly because there was no decent way to flight test the missile, each flight would end with the need to find a safe place to crash land a nuclear reactor..

http://www.designation-systems.net/dusrm/app4/slam.html
http://en.wikipedia.org/wiki/Project_Pluto
http://www.globalsecurity.org/wmd/systems/slam.htm

[Admiral Valdemar]

The concept is sound, as the Tory fission engines demonstrated. The Macross series of animé also uses the concept of fusion based drives the the aircraft, having a turbine and heat element setup for atmospheric flight, and a standard VASIMR like plasma mode for space or when atmosphere isn't present.

The problem is obvious. We don't have a fusion reactor that can break even, letalone be small enough for an aircraft. That leaves fission which, unless you plan on putting on something like the good ol' Flying Crowbar that is Pluto/SLAM or fancy bogging you aircraft down with human friendly shielding, won't be too economical right now.