I have a question regarding intake sizing. I am building a UAV powered by a single RAM 1000 and was wondering if there is a minimum cross sectional area that must be maintained. The plane will have dual intakes like an F-15 or F-4. The length of the intake duct is about 3 ft. to the front of the engine. The engine will sit in a Jet Tech Bypass and will use the Jet Tech tail pipe. The tail pipe is about 13 inches in length. As with most planes internal space is tight so the smaller the intake ducts the better.

Thanks,
Pete

Your Final answer should come from Albert.

However in the mean time, when I asked Rei the same question about a year ago, he stated that you need at least 7.5 Square inches of intake. I would plan for at least eight square inches just in case. Since you have twin intakes, take in consideration any curves or other obstructions, try to keep a smooth airflow.

Turbulence

Hello Pete; The intake needed is correct at about 8 inches. Intake and bypass design is complicated and not as simple as it may seem. You need to figure out mass flow of the engine, air temp, tailpipe velocity, intake size, bypass ratios and many other things. A good design can loose as little as .5 lbs and a bad design can loose you as much as 25%. My best advice to you is to look at the BVM Bandit design as a good foundation. Bob has spent a great deal of time and money with an engineer to figure these things out.