I apologize for any confusion, but it seems there might be a misunderstanding. The Thunderbird aircraft I mentioned earlier, flown by the United States Air Force Thunderbirds aerial demonstration squadron, are F-16 Fighting Falcon fighter jets. They do not have any rockets on their undersides or any association with the Thunderbird One or Thunderbird Two mentioned in your question.
"Thunderbird One" and "Thunderbird Two" are actually fictional vehicles from the British science fiction television series called "Thunderbirds," created by Gerry and Sylvia Anderson in the 1960s. The Thunderbirds series featured a rescue organization called International Rescue, which used advanced vehicles to respond to emergencies and save lives.
In the Thunderbirds TV series, Thunderbird One was a hypersonic aircraft used for reconnaissance and initial response to emergencies. It did not rely on rockets to get airborne but instead used conventional jet engines for takeoff and flight. Thunderbird Two, on the other hand, was a heavy cargo aircraft capable of carrying rescue vehicles and equipment. It did not have rockets on its underside either.
It's important to note that the Thunderbird aircraft from the Thunderbirds TV series are fictional and not related to the Thunderbirds aerial demonstration squadron or the F-16 Fighting Falcon aircraft flown by the USAF.