Im building a new jet thats completely built up from balsa and i need a brushless motor, edf untit, and speed control to power the beast. How do i calculate how much thrust i need to power it? And how do i look for such specifications from a brushless motor? Is there any other factors i should consider when finishing this jet? Like wing loading or such? Im loosely copying another plane in this planes design and my jet is plus or minus 2 inches on every dimension when compared to the other plane. Everything but the wings that is, because the wings are forward swept and are maybe 25-30% smaller. I think since its a jet thats gonna be travelling pretty fast, that the percentage won't matter much. Can anyone help??

EDF's don't generate thrust quite the same as props so it's hard to pin down an answer. EDF powered models that can barely take off from the ground because the fan blades are starved and operating in a near stalled condition end up flying far faster than equivalent prop powered planes in flight once the fans are being fed with adequite airflow and the blades are not operating in a stalled condition. Prop planes with high pitched "racing" props have some of the same issues. So there just isn't a way to pin down what you're looking for that I know of. That leaves you with just basing the performance on published real tests of motor and fan unit combos.

You're doing the right thing by copying an existing design. But you're going to get into trouble by making the wing area smaller. Instead scale up the span and length enough to keep the wing area to within 10% of the other model. But you'll also need to watch the weight. You must keep the weight down to no more than what the other model weighs if you expect to match the performance of that model. Or if you know you can make your model lighter enough that the wing loading on your smaller wing is the same as the other model then by all means carry on. By making the smaller wing have the same wing area it'll tend to crank around in the turns just as well and the lighter weight will assist with climbing and recovering speed after high G turns where a lot of speed is bled off.

Other than this your best bet would be something like Motocalc or similar that has some fan and motor options to select from.

And if i want to leave the wings 25-30% smaller, can i just make sure i generate enough thrust to make it fly? im not trying to match the preformance, just to make it around the same size.

I just calculated my custom jets wing with the original. My jets wing covers the original by 94 percent. Is this acceptable?

Yes that will do nicely. It's not about making it faster. It's about keeping the wing loading about the same so that your stalling and landing speeds do not need to be crazy high.

And anything you can do to lighten your version will make the model fly faster, turn harder without bleeding off as much speed or snap rolling out of the turn and generally make the model more fun to fly.

Best of luck with your design.

To make it lighter i was going to build the whole airplane out of light balsa and sheet in in balsa as well. This way i can lighten the load, then when i calculated the full weight and wing loading i can look for an airplane with the similar weight online and copy its power system.

Yep, it's not very scientific to just copy the parameters of another design but in this case it's a good way to go as your first step into EDF jet models.

I moved your other thread to the Electric Jets forum because it has no connection to aerodynamics any longer.

It may not be an extremely scientific way, but it still includes calculations on wing loading, cg, and a ton of other factors. See, im just copying the length and width of the original plane. Everything else is created either by hand or with a calculator