Interceptor Aircraft

I have the desire to develop my own Interceptor aircraft that will be able to, well, intercept things. I'm trying to get more nationalized designs so I don't have to be so reliant on foreign imports, and to have an upper edge on any opponents I may face. So, my questions are these:

What are the best materials to build an interceptor aircraft?
What is the ideal thrust-to-weight ratio?
Is it more powerful with one or two engines?
What kind of RADAR system should I be looking at?

Any other information you could provide me with that would be useful I would be more than grateful for. Thank you.

Interceptors are fun! RL doesn't like them anymore, but they're purrrrdy!

Your cost and manufacturing divisions will say steel, weights (and stress) will want titanium composites, and corrision/fatigue will want it all made out of one specific aluminum alloy.

"It depends on what part we're talking about" is a superficial answer. Really, if you're not going too fast, mostly aluminum alloys with lots of cad-plated steel where the stresses require it.

If you're going really fast, titanium where you have to pay for it, nickel steel where you can get away with it, and aluminum where you're sure it'll be cool.

If you're going light and fast at any cost, expect titanium, composites, ceramics, high temp steels, and other wacky stuff.

As high as you can go while still retaining range to go the distance, exhaust velocity to go the speed, payload to carry the missiles, and fatigue life to not need a rebuild every flight. (1.0-1.2 is the range you should aim for at your intercept missoin takeoff weight)

Airplanes are probably best characterized by three parameters: wing loading, thrust to weight ratio, and lift to drag ratio.

If you can keep everything light enough, there's no reason a single engined aircraft can't be just as good as a twin engine (F-16, F-104, etc) up to a certain point.

A big farking AESA with burn-through-stealth capability, and a really really good datalink to a ground based RADAR set.

Refer to the first generation F-16, the F-104 (early marks), the MiG-25 (in concept), the Avro Arrow (to a certain extent), and other real life intercetptors and lightweight fighters.

Thank you so much! Though, I do have a question about this part:

How do I design/find a 'burn-through-stealth' radar system?

How do I design/find a 'burn-through-stealth' radar system?

Make it an L-band radar. They have scan at a lower frequency than the X-band radars most fighters have and can find stealf aircraft more easily.

You might want to have an X band radar as well though, maybe in the leading-edge extensions.
L band radars tend to be more cluttered.

Learn from Foxbat, give it some hilariously powerful radar.

Saphir was one of the most powerful radars fitted to an aircraft, wasn't it?

A really large X-Band radar.

Lower frequency radars aren't accurate enough within the constraints of the aircraft. Higher frequency don't have good enough long range or bad weather performance.*

Peak power/short pulses are less important, longer coded pulses can provide similar range resolution and superior jamming burn-through range. When it comes to stealth targets the most important factor is the sensitivity of the receiver.

Equally worthwhile are an IRST, an EO camera and a laser range-finder.

*Putting low frequency radar in the wings is a fancy unconventional approach that is being developed IRL but has not reached the front lines. It would be a big boost in the aircraft's search capability but would only be a supplement to the primary X-band radar.