The correction for cruising height would be insignificant.
A ram-jet is an air-breathing engine and would be confined to the atmosphere. Even a 60km cruising height (which is much higher than what would be used) would only correspond to a 1% increase in flight path circumference compared to the surface value of 40.000km.
I think the GP might have meant that Mach 3 at ground level is even more technically astonishing - a lot of the historial benchmarks for airspeed (mach 2 fighters and interceptors, the SR71's mach 3) were only valid at very high altitudes were the atmosphere is sufficiently thin to make the achivement teneable from a drag and heat-flux perspective. To cruise along at Mach 3 at sea level is a quite astonishing display of brute force.
I'm skeptical of such a capability. Even granting the engines the power and durability to do that, what about the rest of the airframe and avionics? How do they prevent those from being baked if not outright melted? The SR-71 required a substantial engineering effort to withstand the shock heating at that speed but the SR-71 flew very high in thinned air.
Over enemy territory, ground-level flight was considered a feature, as the passing missile would shred the ground with sonic shockwaves, and bake it with radiation from its unshielded reactor.
One of the most evil military designs ever conceived.
> as the passing missile would shred the ground with sonic shockwaves
Reminds me of this “oopsie”:
> Three-quarters of the windows in an eight-block area of downtown were shattered by a sonic boom accidentally created by the Blue Angels, the U.S. Navy's flying aerobatic team
To be fair, in the wikipedia article they talk about the radiation hazard being minimal and not part of the design - at mach 3 any exposure to the reactor is so brief it doesn't really do damage.
Of course, it going mach 3 at 1000 feet or lower, is going to knock your toupee right off.
Cruise altitude for a ramjet would be between 5 and 20 miles up. The earth has a 4,000 mile radius. There would be no meaningful difference because of the change in circumference because of altitude.
This reminds me of the Bob & Ray satellite. Their plan was to put a satellite into an orbit 50 feet up, and then sell advertising space on the sides of it.
A ram-jet is an air-breathing engine and would be confined to the atmosphere. Even a 60km cruising height (which is much higher than what would be used) would only correspond to a 1% increase in flight path circumference compared to the surface value of 40.000km.