Rockets can only give thrust for very short periods of time - usually not much more than ten minutes as they burn their fuel at an astonishing rate. Look at the Space Shuttle. Its rocket motors only fired for about 10 minutes - and look at the size of the fuel tank needed.

And, if a rocket COULD accelerate a 747 to much higher speeds, the aircraft would have to be redsigned completely to cope with those high supersonic or even hypersonic speeds. Imagine a 300 seater X-15?

Actually, the Shuttle is only completely vertical for about the first 10 seconds after launch. If you recall there was the radio call, "Roll Manoeuver Complete" which was the moment where the entire Shuttle rolled and pitched at an angle that took it out over the Atlantic in a gradually curving arc. By the time of main engine cut-off (MECO) they were flying parallel to the earth's surface at an altitude of about 130 plus miles and travelling at almost 17,500 mph.

There are massive problems with maintaining high speeds within the earth's atmosphere - mainly associated with aerodynamic heating through friction with the atmosphere. The SR71 was made of titanium to enable it to fly at Mach 3 (about 2,000 mph - not 3,000 mph). That, of course, was jet powered, not rocket powered, and needed to be refuelled in mid air numerous times during a mission. Titanium is also expensive stuff and not practical for airliners in large quantities.
The fastest atmospheric aircraft ever, the X-15, was made from even more exotic metals, such is Iconel X - which allowed it to reach speeds within the atmosphere of up to Mach 6.7. But even then, the structure became very hot and on the one and only Mach 6.7 flight, the structure was so badly heat damaged that the X-15 never flew again.
Being rocket powered, the X-15 needed to be hauled to altitude under a B-52 and even with large strap-on fuel tanks, only had enough fuel for about 5 to 10 minutes of powered flight.

Finally, rockets are bloody dangerous. They would never be sanctioned for an aircraft designed to take litle old grannies and toddlers on a jaunt across the Atlantic.

I don't think composites confer massive amounts of heat resistance over metals. their main benefit is strength/lightness. The big area of improvement in heat protection is in the use of glasses and ceramics. The Shuttle was protected by ceramic tiles which, in theory, were reusable - although they had their problems. They certainly worked, as long as they remained attached, but they were extremely vulnerable to damage from the slightest impact. Even rain drops would destroy a ceramic tile at high speeds.

I couldn't see a commercial operator wanting to operate a machine that had a vulnerable heat protection system attached to it.

The jet/rocket combination has been tried on some aircraft. It has always proved very, very difficult to handle and has always been abandoned as a practical proposition.
The nearest thing to the regular use of rockets on "normal" aeroplanes has been the JATO system which is sometimes used to allow heavilly laden transports and bombers get out of tight airfields. And even this system has fallen out of favour in recent years as conventional jet and turboprop engines are now so powerful the need for rocket assistance is almost ancient history.

Some examples of JATO -

There is no techincal reason to prevent your idea from being developed.

There is also no economic reason to justify that development!


In the 1960's the USA plowed tens of billions of dollars into ultra high speed reconisance aircraft like the SR-71. Not one of these planes was lost to "enemy action", and it turned out that the planes real enemy, the politics that finally ended the program in the early 1990's, was rooted a lot closer to home as the incredible cost of the program became untenable to successive US regimes..............

Yep can you imagine paying passengers getting on an aircraft with panel gaps big enough to stick your finger in and the smell of aviation fuel as you load up through the puddle of fuel.

Scram jets are probably the way forward for high speed at altitude, trouble is getting there in the first place.

Over the course of its lifetime a civil airliner will burn ~$1 billion of fuel, which is why long haul airline frequently turn over their fleet for newer aircraft with older planes going to cargo operators and charter airlines.

Given that the aircraft burns many times it's purchase price in fuel you can see that for long haul fuel costs are pretty dominant. Anything which flies faster will burn a lot more fuel and therefore cost a lot more to operate.

The economic argument for long range high speed flight has already been tried and lost with Concord.

I guess that's what's prompting my question - Concorde was developed druing the 1960s, has the game not moved on a bit since then?

And that type of basic technology has not moved on enough to make rocket power either an economical nor a safe proposition for everyday use.

I doubt if it ever will. As has been mentioned, the best chance to see rocket technology work on a more practical level is something like Skylon - but that is still quite some way in the future.

Don't let Tony Ben see you spell it that way, or the Entente Cordiale might be lost ;-)

Too many people travelling as the cost travel gets relatively cheaper?

When Thomas Cook started in 18-something you had to be landed gentry to tour Europe; now any chav can do it with benefit money. And so all roads and trains and planes are crammed.