Simulator Report: Hercules II Update and Testing

Kromey Kaerospace engineers, assisted by Jeb, spent hours in the simulator studying the failures of the Hercules II and IIa rockets and mocking up proposed changes to the design to meet the dual goals of stable, controllable flight, and delivering enough ΔV to put the heavier Andromeda II CSM into orbit.

KK engineers began by adding the newly-developed inline reaction wheels to the stack. While the extra weight reduced overall lifting capacity slightly, it nonetheless improved stability considerably, however the rocket still had a tendency to lose control and tumble dangerously.

Engineer Volta Kerman was the one who spotted the final key to the puzzle of the Hercules’ failure: Contrary to the original designs, which specified the use of the LV-T45 engine, the rocket had in fact been built with the LV-T30 engine! While the latter delivered slightly greater thrust while costing less — likely the reason the contractor had switched the engines out — the T30 lacks the thrust vectoring capabilities of the T45, leading to a rocket that must rely solely on the torque of the command pod, and explaining why the additional torque added by the reaction wheels improved the rocket, but did not quite solve the problem.

However, this error (giving the contractor the benefit of the doubt, seeing as how it was Jeb’s cousin and therefore totally trustworthy and honest!) did give rise to a novel concept at KK, and the redesigned Hercules IIb rocket uses in its initial stage a single T30 engine ringed by T45s; this provides the rocket with improved thrust over using just T45s, however it also provides ample control for the rocket as well.

Unfortunately, the initial tests of this redesign proved it fatally flawed: As the computer rapidly reoriented the thrust vectoring of the T45s in order to maintain a vertical liftoff, the radially mounted fuel tanks began to flex and oscillate, growing more and more violent until the rocket’s lower stage self-destructed. Fortunately, Engineer “Duckie” Kerman had just completed the finishing touches on what he likes to call “space Duck tape”; these struts provide ample structural reinforcement to the rocket’s boosters to keep the lower stage from oscillating, and result in a considerably more stable flight overall.

In fact, initial testing suggests that the improvements to the stability, despite the added weight of the reaction wheels lower the theoretical performance of the rocket, actually give the rocket considerably improved lifting performance, with the simulations suggesting that the initial stage alone is very nearly sufficient to get the Andromeda II into space, leaving the second stage almost completely full and able to perform the orbital insertion and any necessary corrections. While the simulation was not taken that far, the Hercules IIb’s second stage may even have enough remaining ΔV for a Munar FRT.

Mission KK-Ke-0008, with Bill once again at the controls, will be the initial flight of the redesigned Hercules IIb; this will be the third attempt at completing the mission originally planned for KK-Ke-0006, with the additional mission goal of testing the potential for the Hercules IIb upper stage to inject Andromeda II into a Munar FRT.

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