I can meet with you and help you solve your problem. I am a matlab person with proficiency in control problems, and I will bring with me an experienced aerospace engineer for the flight model problem.
We cannot bid a low fixed price on this project because we don't have enough information to estimate actual cost. We cannot rely on your assertion that the problem takes "x time" to solve due to lack of information.
You are getting 5 hours from 2 engineers ("less than a day") for the price I've specified, with no guarantee of solution. Contact me if relevant.
If you feel the problem is smaller in nature please feel free to contact me through PM and explain the details, I will be happy to revise the bid details if I feel this can be solved withing a short time frame.