I didn't know you can delay particle effects...how?
juLLe, why would you want to delete the exhaust from the tomahawk after 2 seconds?
That would [and this is just my opinion] make it look unrealistic because tomahawks leave an incredible amount of exhaust smoke,sometimes even covering 1/3 of a missile cruiser.
Your TH does look good though. Were you able to get it to slightly wobble and curve in mid air before going to its target?
What would be cool is to have it take off,up and at a slight angle with the exhaust that you have now.
Then have a second bigger exhaust and afterburner flare effect ignite and the TH would instantly accelerate and take off to its target
