What causes colors in smoke from the Red arrows?

Answer 1

The basic vapour colour is white, produced by injecting diesel into the hot exhaust from the jet engine. This reaches temperatures of over 400 degrees centigrade and vaporises immediately. The blue and red colours are made by mixing dye with the diesel. The dye and diesel is stored in a specially-modified pod fitted to each of the aircraft. The pilot releases the liquid by pushing one of three buttons on the control column. During the display each aircraft can produce smoke for a maximum duration of seven minutes. This gives the pilot five minutes of white smoke, and one minute each of red and blue smoke. For this reason, a 'smoke plot' is worked out extremely carefully to ensure that no aircraft runs out of smoke before the end of the display. Replenishing the diesel/dye mixture is done in two separate operations. First, the pressure which has built up in the centreline pod is released. Then, diesel is fed into the correct valve at the front of the centreline pod from a diesel bowser. There are no indicators to show when the diesel section of the pod is full - a technician is stationed at the rear of the pod to watch carefully for white vapour emitting from the vent pipe. Once the vapour is seen, the call of "It's Gone" is given and the technician in charge of the feeder pipe connected to the front of the pod turns the diesel supply off and shouts "White's Off". Replenishing the coloured dye/diesel mix is supervised particularly carefully to ensure the right colour mix is fed into the correct section of the pod. The most crucial piece of equipment for the team's work is the Dye Rig, which contains the dye/diesel mixture. Every display uses one barrel of red dye and one of blue dye, which are then topped up with diesel. The Team always fill the two colours in the same order to prevent confusion; red then blue. One technician operates the flow buttons on the dye rig, one connects the pipe to the valve at the front of the pod and one checks for the level at the rear of the pod. The call goes out "Red On", followed by "Pumping Red", at which point the Dye Rig operator presses the button to start the replenishment process. Again, there is no dial or gauge to show when the pod is full, and so the technicians have developed their own method of ensuring that the coloured liquid does not overflow. The only way to tell how full the pod is to press your ear up against the back of the pod to hear when the valve begins to quietly 'chatter' - quite difficult on a noisy airfield! Again, the urgent call of "It's gone" is followed by "Red Off" from both the Dye Rig operator and the pipe connector. The whole process is then repeated for the blue mixture. As you can imagine, the job of replenishing the dye and diesel can be a messy one! The dye is not easily removed if it stains skin and clothing. In order to protect the technicians against spillage, the Dye Team wear special protective silver overalls, thick gloves and goggles. Because of their protective qualities, the suits get extremely warm! Next time you watch the team replenishing diesel and dye on a hot summer's day, spare a thought for the hardworking Dye Team.