I have no experience in rocketry, but I got really curious lately. I was wondering, is it possible to create a missile? Is it possible to put rc plane servos on a rocket to tilt the fins and change the rocket's path? I still have no clue how any of this will work, but I want to see if this is at all possible.
You set off warning bells by the word "Missile"
Guidance to help models go UP, unable to track anything, yes. Guidance that is capable of making a model go after a target in the air or on the ground, NO.
Try try for purely horizontal rocket powered flight after a near vertical launch, very risky and some practical issues to resolve even if you had experience. Could be done legally but under limited conditions (one big one being at a site with nothing and nobody anywhere near the worst-case impact area far downrange if it failed to recover safely) and only after a LOT of experience flying vertically first (pretty much requiring custom electronics, or custom coding, or both). I mean, I am thinking how I'd do it (horizontal flight under control after a near-vertical launch) with what I have experience with... and it's not there. I'd have to either cobble up two different guidance systems or get DEEP into coding Arduino guidance (I can get Arduinos to blink or count, but guidance coding is way beyond me)
As others recommended, build some small models first just to get the basics of the hobby.
Get a copy of The Handbook of Model Rocketry.
Do not even F*** with homemade motors. I'm not even talking about the personal safety issues or whatever. I'm talking that if you want to build a rocket with guidance, concentrate on the GUIDANCE part, and not making your own engines. Because the engines will likely be very unreliable, poor performance, etc.
After you have built some models that fly successfully, then you could build a small prototype for your guided rocket. My Sunguidance rockets that used aerodynamic controls (nose fins) , were BT-60 (1.64"), about 3 feet long, and 12-14 ounces. They used 24mm engines, mostly 2-staged D12's, a few times E6 (7 second burn). The gimbaled engine project used 2.6" diameter, Estes BT-80, also about 3 feet long or s. Its first flight used 2-staged D12, first stage fixed engine to get a vertical liftoff, then staged where the gimbaled upper stage veered off-vertical to steer for the sun. After that, it used an F15 a time or two, the rest were F10's (about a 7-8 second burn).
Gimbaled engines are tricky, far easier to go with aerodynamic control fins.
Thing is that those were relatively inexpensive rocket airframes easy to build and repair or replace. And the mechanisms were not too difficult to build/replace in case of crash or need to change design. Also of course, not as expensive to fly as HPR, and NOT requiring a scheduled FAA waivered launch "somewhere" to fly, I could test these any day I wanted to at a local launch site. Many times I did several test flights on the same day.
That is how you can learn how to do it well, and reliably, with less work and less cost for the amount of experience and learning you'd gain (and less danger in case things go wrong with the guidance than if it was a big HPR rocket). Then once perfected you could do that with a scaled-up larger rocket.
So, having said the above, some guidance info. Link to my 1988 Sungudiance project plus some info on the 1989 gimbaled engine project:
https://georgesrockets.com/GRP/RandD/Sunguidance.htm
But I do not recommend sunguidance. It has been superseded by modern electronics. Some have worked up homemade guidance controllers, often using Arduino microcontrollers systems with custom guidance. Joe Barnard of BPS.Space is selling guidance controllers, as well as gimbaled engine mounts.
https://bps.space/
There is a model airplane "autopilot", the Eagle Tree Guardian, that makes for a fantastic vertical guidance guidance controller. Alyssa Stenberg tested it for her 2014 NARAM R&D project. I wrote about the Guardian in this thread:
https://www.rocketryforum.com/threa...ed-rocket-guidance-eagle-tree-guardian.61680/
Sunguidance project video:
Alyssa Stenberg's project presentation with flight video:
BPS.space channel video: