ema schematic.JPG

credit:NASA / caption: Originally designed in 1993 the electromechanical thrust vector control remains on the shelf

It didn’t last that long and this procurement, which Hyperbola has had a peculiar interest in, had the potential to deliver mass reductions for the Ares I crew launch vehicle first-stage but on Friday 13 March (oh no!) the electric thrust vector control (TVC) was quietly cancelled

The purpose of this amendment is to cancel Solicitation No. NNM08261607R.   Proposals may be re-solicited in the future after further programmatic decisions are made.

The aft end of the Ares I has certainly been getting more complicated over the last couple of years what with extended nozzles and oscillation mitigation systems and then the electric TVC

With a Request For Proposals release delayed twice from the original August 2008 publication date to November and then to December, with a January 2009 submission deadline for industry bids, Ares project office manager Steve Cook told Flight that the electromechanical TVC was a “potential downstream upgrade”

Not any more

But the TVC’s importance can’t be discounted. Below are some of my notes (including spelling mistakes) from the AIAA SPACE 2008 conference’s Ares I-X session and for that test flight TVC operation is critical

will add pre-programmed inputs into TVC to minimise impact of loads and trajectory

frequency sweps done on pitch and yaw axes, to get data on flight vcontrol system reposne and aerodynamics
will have brief tvc pulse late in fligt to get strutural reposne
will disable RCS for 1s every 10s

38-44s pitch and yaw frequency sweeps on TVC during transonic
48-58s pitch and yaw frequency sweeps on TVC during maxq

One also has to wonder if the electric TVC wasn’t a possible candidate to aid the lift-off drift issue. Would an electric system have a quicker response time than a hydraulic one and would that help in those crucial few seconds?  

But whatever electric TVC could or could not have been used for, NASA’s first stage prime contractor Alliant Techsystems (ATK) has also been looking to lower life cycle costs potentially with a helium TVC system instead of Shuttle’s legacy hydrazine powered hydraulic approach – perhaps the electromechanical alternative was to be traded against helium?

Following this Ares I igniter press release by NASA it really would appear that those steel casings will be a very lonely flight proven part of the Ares I crew launch vehicle if ATK gets its way – unless their replaced of course