Re: Space Shuttle Grounding....depressing....

Matt Ion wrote: 
Andrew Swallow wrote:

Matt Ion wrote:
[snip]


Having the fuel tank where it is isn't really a mistake per se; it's a design necessity. Launching with cold-damaged seals in the solid-fuel boosters despite a manufacturer's warning against just such a problem is a mistake. Coating it with a flaky material that sheds chunks during liftoff is a mistake. 



Since the main engines are in the orbiter it has to
be at the bottom.  The main fuel tank could have been
placed above the orbiter.  Fuel pipes through the
nose, with covers to give it a nice aerodynamic shape.

When the fuel tank is jettisoned it would have to
be pushed sideways to get it out of the way but
that is not hard.


True, but the support structures would have been a lot more complex, especially to get any decent amount on strentgh in them. The Orbiter would then have to support the full weight of the tank through whatever structure supports it on the ground - right now the SRBs support the whole structure and the tank supports the weight of the Orbiter - or you'd have to add something to the launch structure to help support at least part of the tank's weight.

During ascension the engines take the weight of three times the entire structure. Once the SRBs have been jettisoned the weight of the orbiter, the fuel tank and the remaining fuel have to be carried by the current orbiter's skeleton.

If the fuel tank is above the engines the load baring structure can be simple columns, as used in buildings. With the tank off to the side the structure is that of a crane. The connecting bars acting as leavers multiplying the forces enormously. The centre of gravity also changes during flight. This will require a very complicated structure.


Then you have to figure out where to put the SRBs - you couldn't leave them on the tank in its current design, as the Orbiter would then be in their exhaust wash, unless you redesigned the tank and/or mounting system to hold them FAR out from the ship or splay them outward, although it's still risky putting the shuttle in between their washes. Or you could latch them directly to the shuttle, but that would translate a lot of vibration to the orbiter. 

Or give the orbiter a fourth engine and a bigger fuel tank.

The SRBs are heavy so the mass trade off could be very interesting.

Andrew Swallow

.

Relevant Pages

  • Re: Space Shuttle Grounding....depressing....
    ... The main fuel tank could have been placed above the orbiter. ... True, but the support structures would have been a lot more complex, ... support the whole structure and the tank supports the weight of the ...
    (rec.arts.sf.tv.babylon5.moderated)
  • Re: Asymmetric loads on WW2 fighters
    ... I assume that the drop tank would be emptied first and the associated ... weight changes progressively trimmed out. ... But when the bomb is ... because the fuel tank pylons are closer to the center line. ...
    (rec.aviation.military)
  • Re: Hydrogen fueled Helicopter - more Mook idiocy
    ...   Who knows? ... weight system for aerospace applications. ... a tank holding 10 metric tons of hydrogen has a voume of 142.86 cubic ... that is whenever the whole truth and nothing but the truth ...
    (sci.energy.hydrogen)
  • Re: Hydrogen Cars, Trucks, and Buses Are the Answer Indeed
    ... weight, not energy per unit volume that is the issue. ... Here are the energy densities and tank fractions for jet fuel and ... Take off Weight 298 tonnes ...
    (sci.energy.hydrogen)
  • OT now: Waterbeds and Airbeds
    ... ->> We have discussed the weight of tanks before, will the floor need extra ... Insurance claims due to tank ... ->> Perhaps we should consider things or objects of equal weight, ... I can afford it I will get one of the "sleep number" beds you ...
    (rec.aquaria.freshwater.misc)