Aug 22 2017

Deuce Flight Trials Lead to Redesign

The previous week saw the Deuce take to the skies once again for two test flights after spending more than two months being rebuilt since crashing back in June. The first flight was still hampered by over-sensitive controls and after they were dampened still further for the second flight it became apparent that the aircraft was inherently unstable – Captain Jebediah could now feel that it wasn’t him causing the plane to pitch up & down violently (at some points there were momentary forces as high as 7Gs while traveling over 140m/s). This meant that more work on the design of the Deuce’s air frame was needed, and C7 engineers quickly got to work playing around with new models in R&D’s modest wind tunnel, trying all sorts of things like moving the wings forwards, aft, up, down and even trying new tail configurations. After seeing no major changes with tweaks to the aerodynamics (except for a minor but noticeable improvement closing up the tail section) attention was switched to the plane’s mass/lift balance. The center of lift was behind the center of mass, which is good, but the two were fairly close together, which can be unstable. Now that they knew how unstable it could be, efforts were undertaken to shift the CoM further away from the CoL. This was done by moving the engines and fuel tanks further forward on the wings, and finally wind tunnel testing showed a significant improvement in the pitch stability of the aircraft.

These changes to the Deuce will come at a significant cost in both funds and time, as they are not minor. The tail section has already been reworked once from the original design to tilt upwards but it did not actually move the tail so HAB workers were able to retrofit the changes onto the existing tail boom. With the new design the horizontal stabilizers will have to be completely removed and remounted, leaving the original mount position open. Rather than applying a patch, C7 feels it is safer to just order a new tail section. Likewise, with the engines, they are mounted into the wings, which means moving them forward would leave a gap behind them that would need to be patched over. However even if the wings were to be patched, moving the engines forwards increases the stress on the wing so the entire wing section would likely remain structurally weakened. Ordering new, stronger wing sections and a new tail boom will take at least 2 weeks as these parts are still very unique to construct. About a week or so of assembly after they arrive and the Deuce should be ready to fly again, hopefully this will be its final configuration. You can get a better idea of the changes in the comparison below: