if you don't want to have to ignite the second engine manually you can make a two stage rocket. You can make it have a delay too if you want. You do this by taking two rocket engines (the first one sould have a delay time of 0, this is the last number, if you want it to ignite right away) you put one engine on top of the other so that the bottom of one is matched with the top of the other. You then take tape and wrap the two engines. This makes it so that when the engine fires the recovery stage it will ignite the second engine. good luck.