I saw a picture of this the other day and it got me thinking... How does having the shuttle on the back of the 747 affect the factors of flight? My guess is that is provides an incredible amount of additional drag and obviously weight. What I'm really wondering is do the wings of the shuttle provide some sort of additional lift to the entire aircraft?
@fooot beat me to it in the comments but the linked podcast answers all your questions
The shuttle effected lots of factors of flight, in quick summary (from the info in the podcast) the whole assembly was:
- ...aerodynamics not neutral as is answered in this question
- ...Speed limited due to the braces that held the shuttle on
- ...VFR only due to the fact that impacting rain could cause water build up issues in the heat shield tiles
- ...Altitude limited
- ...Bank angle limited
- ...Quite short range by default
- ...Required the orbiter to be empty (although hypergolic fuels were left onboard. All payloads had to be removed if the orbiter was returning something.
- ...Required rib re-enforcements where the braces were mounted
- ...Was quite noisy due to the brackets used to hold the orbiter on
They shuttle carrier aircraft is modified as per the requirements of NASA. For instance, the fuselage is strengthened, vertical stabilisers are added and struts mounted. However your question pertains to the impact on the shuttle carrier performance, which includes (from Wikipedia):
Flying with the additional drag and weight of the Orbiter imposed significant fuel and altitude penalties. The range was reduced to 1,000 nautical miles (1,200 mi; 1,900 km), compared to an unladen range of 5,500 nautical miles (6,300 mi; 10,200 km), requiring an SCA (shuttle carrier aircraft) to stop several times to refuel on a transcontinental flight. Without the Orbiter, the SCA needed to carry ballast to balance out its center of gravity. The SCA had an altitude ceiling of 15,000 feet (4,600 m) and a maximum cruise speed of Mach 0.6 with the orbiter attached.