How much do aeronautical engineers make on average?
That is a very hard question to answer. Since Aeronautical Engineering is an off-shoot of Mechanical Engineering, I can tell you that a starting mechanical engineer will make about $60,000/year. Depending upon a whole lot of factors, maybe a little higher or lower. You may be able to hunt around on the Internet for some salary ranges. But, as you may know, the starting salary is only a part of the picture. In addition to the salary are the benefits: medical insurance, pension, vacation. These benefits can add approximately 25% more to you on top of the salary.
I understand that you are interested in airplanes but, before you make a final commitment to aeronautical engineering, I suggest you look into the job openings for that field (Google it) to see how many companies are hiring in that field and the type of jobs that are open. The first 2 years of engineering school are all very similar and you may find that companies looking for aeronautical engineers will also be looking for mechanical engineers and electrical/computer engineers as well. The mechanical engineering field is very broad which means there may be a lot more opportunities.. What I am suggesting is that you do not specialize too quickly. Determine the field you really want to get into and the job opportunities in that field before you finally decide. Once you make a commitment, then go for it and be the best engineer you can be. It won't be easy, but it will be rewarding.
Hope this helps.
Note: You will most likely make the lower salary right out of school since you don't have any experience. Also, smaller companies tend to pay less and companies in smaller cities may pay less. The higher levels of pay are more likely those that have progressed into management positions after many years.