The worlds new "largest aircraft"

[CAPSLOCKSTUCK]

Stratolaunch

The craft will be larger than Howard Hughes' 1947 H-4 Hercules, known as the 'Spruce Goose,' and the Antonov An-225, a Soviet-era cargo plane originally built to transport the Buran space shuttle that is currently the world's largest aircraft.

Stratolaunch Systems - part of Microsoft co-founder Paul Allen's privately owned Vulcan Aerospace
http://www.vulcan.com/areas-of-practice/space/key-initiatives/space-projects-overview

Wingspan: 385 feet (117 metres)

Engines: Six 747-class engines

Fuselage length: 238 feet (72 metres)

Weight: 1,200,000 lb (544,311 kg)

Maximum speed: 460 knots, 530 mph (850 km/h)

Maiden launch: Flight testing will begin in 2016. The first launch of the space launch vehicle is likely to take place in 2018.

Satellite delivery: Initially, the system is intended to deliver satellites weighing up to about 13,500lbs (6,124 kg) into orbits between 112 miles and 1,243 miles (180 km and 2000 km) above Earth.

Launch sites: Several sites are under consideration, including Kennedy Space Center, Wallops Island and Vandenberg AFB.

http://spacenews.com/stratolaunch-seeks-launch-partners-as-aircraft-nears-completion/

 

[FordGT90Concept]

Oh, it's intended to make getting stuff into low-earth orbit cheaper. Makes sense.

This does not though: "Engines: Six 747-class engines" Airlines hate the 747 engines because they're too inefficient. The best way to get better efficiency is through bigger engines. The landing gear isn't tall enough to fit it with bigger engines. 747s are being replaced by aircraft with two larger engines like the 777. Even the Airbus A380 uses bigger engines for better efficiency.

I don't care for the design either. That wing doesn't look very efficient and what's in that second body? I assume they have to balance the load between the two bodies to keep its flight characteristics in check.

It's also clear this thing moves very slow. Notice how the Boeing 747, Airbus A380, and Antonov An-225 all have swept wings? They operate at about 500-650 MPH (subsonic). I bet this thing can't even get close to 400 MPH.

I really hope they did their math. This aircraft looks unstable.

 

[DeathtoGnomes]

The SR71 had its share of issues that made everyone think its not stable and a fire hazard, notably leaking fuel. Until is was airborne and above 30 (or so) thousand feet, when the leaks sealed up.

Since this plane was designed for high altitude, I'm guessing the 747 engines were modified just for this purpose, plus they have the largest intake of most aircraft engines that might needed for such high altitudes. Plus I'm betting that cost was a factor in choosing that model.

 

[Steevo]

Im sure they mean 747 thrust class, not actual 747 engines, many of them have been rebuilt or refitted with newer engines. In almost every jet aircraft for transport the wings are designed to carry the fuel load and engines, the body provides the primary lift surface for the cargo and or passengers at altitude, this design looks to provide the lift needed to get something heavy off the ground and up to a much higher altitude at lower speed (recent flight of mine was 37,000 ft at 570MPH ground speed using GPS accurate to within 3ft) the higher you go, the less air, and either you need more speed to generate the lift and provide engines with air to burn, or more wing and more efficient engines.


Swept wing allows for more surface area, with less lift, better yaw control, but also higher stall speeds/takeoff speeds.

http://adg.stanford.edu/aa241/highlift/clmaxest.html

 

[natr0n]

All I can think of.

 

[tabascosauz]

Oh, it's intended to make getting stuff into low-earth orbit cheaper. Makes sense.

This does not though: "Engines: Six 747-class engines" Airlines hate the 747 engines because they're too inefficient. The best way to get better efficiency is through bigger engines. The landing gear isn't tall enough to fit it with bigger engines. 747s are being replaced by aircraft with two larger engines like the 787. Even the Airbus A380 uses bigger engines for better efficiency.

I don't care for the design either. That wing doesn't look very efficient and what's in that second body? I assume they have to balance the load between the two bodies to keep its flight characteristics in check.

It's also clear this thing moves very slow. Notice how the Boeing 747, Airbus A380, and Antonov An-225 all have swept wings? They operate at about 500-650 MPH (subsonic). I bet this thing can't even get close to 400 MPH.

I really hope they did their math. This aircraft looks unstable.

I don't think the engining will be an issue. "747-class" is an appropriately broad descriptor. You're thinking of old GE CF6s and RR RB211s on the old 744s; the 748 is equipped with essentially the same GEnx as the 788/789, which also takes the RR Trent 100 not too far off the Trent 900 on the A388...you get the idea. Efficient as can be.

I don't read up on space travel but using something like this to get stuff to LEO sounds strange unless the actual payload can propel itself and just piggybacks off of the craft.

 

[FordGT90Concept]

I was mostly thinking GE90. Those engines hold many world records. They're too big to even mount on the A380.

 

[D007]

Looks like something I'd build in Kerbal space program..lol.. Then I would hope it flys or doesn't fold in the middle. XD
Turbines will take it to max altitude, then that rocket will kick in, to take them into low orbit..
No air = no turbines.

 

[Caring1]

I can't see it working once that rocket kicks in, too much drag and the body will fold with the tails meeting at the rear.

 

[CAPSLOCKSTUCK]

@Caring1


this is how it will work

 

[FordGT90Concept]

Yeah...but how much less force does it take to launch at 30,000-40,000 feet compared to sea level? That's really the only point in doing this at all.

...expending jet fuel to save a little rocket fuel...

 

[Deeveo]

I'd assume you save some fuel like this, I'd guess a plane is a lot more fuel efficient than a rocket. Launching a rocket is all "brute force" to send something up whereas a plane uses air for lift aswell. I'm no aerospace engineer and haven't done any math on this though, but one would assume they atleast made some calculations before taking a project this far. But sillier things have happened though? Like the airport at St. Helenas?

 

[CAPSLOCKSTUCK]

Its the same method that was used 70 years ago when X-1 broke the sound barrier

 

[Steevo]

Yeah...but how much less force does it take to launch at 30,000-40,000 feet compared to sea level? That's really the only point in doing this at all.

...expending jet fuel to save a little rocket fuel...

http://www.nasa.gov/mission_pages/station/expeditions/expedition30/tryanny.html

It allows for so many more things to go to space, due to propellant/weight ratios. Its also not just a 40,000 feet, it can be traveling 500MPH, and the laws of physics still apply, so the body is not at rest.


"The first stage burned for about 2 minutes and 41 seconds, lifting the rocket to an altitude of 42 miles (68 km) and a speed of 6,164 miles per hour (2,756 m/s) and burning 4,700,000 pounds (2,100,000 kg) of propellant" Saturn V

Extrapolating the fuel expendature **IF** it were linear and **IF** acceleration were as well we could say.

Fuel use per second = 29,192 Lbs per second

500 MPH is 223.5 Meters per second so lets say for averages sake 23M/s acceleration after launch clamps are released, so 10 seconds ( I know that its a non-linear rate of change (quadratic) and could do the more accurate math, but its already been done by others and NASA which the actual mean allows for the low and high rate of change) of fuel saved in just acceleration = 292,000 Lbs of payload more.
The site http://www.braeunig.us/apollo/saturnV.htm has quite a lot of graphs and the math done for us, but 12Km of extra height doesn't seem like much, until you realize the lift weight of the rocket has to overcome the fuel expended in the initial lift and its the highest amount of fuel per Km of vertical lift in the whole thing, and every reduction in height and speed allows for more cargo or lower cost.