When I hear about NASA adding a fifth segment to the SRB, somehow it reminds me of this:
Over the summer of 1930, the R101 lay in the Number 1 shed at Cardington undergoing extensive modifications, which were needed following on from her 1929 and early 1930 trial flights. It was already known that both the R100 and R101 were lacking in the disposable lift originally planned at the outset of the Imperial Airship Scheme in 1925. Those involved in the scheme had already learnt that the R100 and R101 would not be viable for full commercial operations to Canada and India, and these intentions were later to be passed on to the new ship, the R102 class. To achieve the additional lift, R101 had a new central bay and gas bag installed.
It was expected that the new gas bag would give her another nine tons of disposable lift bringing her up to some 50 tons. The alterations were completed by Friday the 26th September and the R101 was gassed up and floated in the shed. The “new” ship, R101c, had disposable lift calculated at 49.36 tons, an improvement of 14.5 tons over the original configuration. Pressure was on for the ship to leave for Karachi on 26th September to carry the Air Minister, Lord Thompson of Cardington. Although the target date was on course to be met, wind was to keep the modified R101 in the shed until the morning of 1st October.
Not sure why, though.
Actually, I think that “Sliderule