Complex sentence: It will possess a retractable undercarriage with high pressure tyres and water-cooled brakes; if any difficulties were to occur just before a take-off, the brakes would be applied to stop the vehicle, the water boiling away to dissipate the heat.
Split into simpler sentences: It will possess a retractable undercarriage with high pressure tyres and water-cooled brakes. If problems were to occur just before a take-off the brakes would be applied to stop the vehicle, the water boiling away to dissipate the heat.