Can I use crowdfunding without risking my IP?

Absolutely. You need to file your patent application, even a provisional patent application, before you sell your prototype. This will preserve your US domestic patent rights as well as your foreign patent rights. If it is a prototype and you contemplate "improving" it, you are probably best filing a provisional patent application - note that the provisional application must still be as complete, accurate, and thorough as a non-provisional application so as to qualify as an enabling disclosure and to provide priority for your future-filed non-provisional application. The non-provisional application, as well as a PCT application, which effectively opens the door to most foreign countries, must be filed within one year of your provisional application filing. If you do make improvements, you can file another provisional application for the improvement and then you must still file your non-provisional application within one year of your filing of your first provisional application. For the second provisional application, you can simply add new disclosure to your first provisional application, and then your non-provisional application can effectively be your second provisional application. You need to file the non-provisional and/or PCT application(s) because a provisional application is never examined and will never, by itself, lead to a patent - it simply establishes a priority date so as to provide you with the earliest date possible for your UAV prototype filed in the patent office relative to any other patent application for a similar invention filed by someone else.