Antonov 225 Split Tail

[aviationluver]

Does anyone know why the vertical stab is split on the Antonov 225? I would think that the vert stab is split because a large amount of flow would be blocked by the fuselage during landing and high AOA conditions, thus causing a loss in directional stability.

What do you think?

[John Farley]

Sorry that was not the reason.

The aircraft was designed to carry large external loads on top of the fuselage - for example it took the Russian Shuttle to Paris one year.

[ImbracableCrunk]

JF is correct.

Check out the Myasishchev VM-T Atlant as well:

VM-T Atlant Description

MAP tasked the OKB-473 design office (Antonov) to design this plane. By then the work on the AN-124 'Ruslan' was well advanced, so Antonov took the decision to build this new plane (AN-225) based on the design of the AN-124. Unfortunately much time was wasted in discussions with Antonov and the prototypes of the Energia LV and Buran were nearing completion in the mean time.
Seeing that the Antonov design office had still troubles with developing its plane the Myasishchev design office suggested to modify the bomber 3M to carry those loads and renamed it 3M-T (T for Transport). Other design offices suggested solutions but they were soon dropped, using an IL-76 Candid, or two helicopters Mil-Mi 26 (the carriage of the tanks proved to be too hazardous). The transformation project consisted of using 3MD model (bomber with refueling probe) by changing the rear part of the fuselage. Indeed, the transport of a load like the Shuttle or Energia's tanks makes a lot of turbulences at the rear of the plane, they should replace the single vertical stabilizer by a twin tail. Many tests in wind tunnels were performed and proved this design to be reliable.

[aviationluver]

Thanks for the info. If that's the case, do you know why the B747 which transports the Space Shuttle does not have a split Vstab?

Look forward to your response.

[musicalaviator]

Thanks for the info. If that's the case, do you know why the B747 which transports the Space Shuttle does not have a split Vstab?

Look forward to your response.

Possibly because it effectivley does.

refer to picture.
Shuttle to catch lift back to Florida on board 747 - Science

[Whitehatter]

It does, in a way. There are two additional vertical surfaces mounted onto the horizontal tail surfaces.

The AN-225 was conceived to carry the Buran shuttle around the former USSR and still has the two humps roughly above the wing spar where the carried vehicle was mounted.

[asyncio]

It has extra vertical sections on the outside of the tailplane. I guess that's because it was much easier than redesigning the whole tail section.

[aviationluver]

Thanks for your responses. Very good answers and no smart a$$ remarks

[aviatorhi]

If that's the case, do you know why the B747 which transports the Space Shuttle does not have a split Vstab?

As mentioned earlier it effectively does, but time "buries" our perception of things. Remember that the 747 was designed first as a military heavylift plane then matured into a passenger jetliner in the 60s. The space shuttle was designed in the 70s-80s. The 225 on the other hand was purposly built with the intent of tranporting the Buran.

Also, I'm guessing that the size of the rudder is more manageable (design/structure wise at least) if it is split, that would be a pretty tall rudder if it was a single centerline unit.