All we know is that there was one parked at Gar's Emporium. Apparently the Kilrathi had captured it and made it part of their fleet, but later sold it off…

The Wu are pretty big fellows, which means that they probably evolved in low-G worlds. Thus, the amount of energy required to reach space is comparatively low. Plus, low-G planets have pretty thin atmospheres, which reduces air drag, making it even easier to reach space. So we could theorize that the Wu,

• a) Had an easier time becoming a space-faring race than most.
• b) Their low tolerance of high accelerations probably led them to build ships with relatively smaller engines, which take their sweet time to reach orbital velocities.
• c) Their ships are probably larger, vis a vis ships of equivaltent classes and roles from other races, given that they are larger fellows, and given that wingspan ought to be relatively large in a thin atmosphere.
• d) They have less pressure to have “pure” space ships, than say terrans and kilrathis; and probably a comparatively larger portion of their ships are (low-G world and thin atmosphere) flight-capable.
• e) Ergo, a larger relative proportion of their their spaceships look like very large supersonic planes; but by the same token have trouble achieving lift at subsonic velocities.
• f) From all the above, we can infer that rockets were never discovered or invented by the woo, and that their spaceports must have looked like very long airstrips, to allow their spaceships to reach high lift-off velocities, while doing so without high acceleration.
• g) The fact that they put up a fight at all probably implies that they had a large number of ships; and if a large proportion of them were ground-based, possibly much of their homeworld's equator must have looked like a continuous air-strip.