Your question is not clear. You want to fly Dubai for 3 days is ok but what did you mean by without RP?

As per your profile you are an Engineer and if that is what is your profession on your ID you can availa on arrival visa at Dubai Airport but if you are planning to travel by Fly Dubai then you should arrange a visa first. Fly Dubai will not take Passengers who are taking on arrival visa. They will arrange the visa for you if you want.