I'm not an engineer but I've been flying model aircraft for 30+ years.The problem with model jet engines is the fuel system,which they have cracked with modern micro electronics and radio control.I have just purchased a Wren turbine with electric start,Fadec,and various other gizmos.It is a little jewel.
As far as pulse jets go then the Dutch had a display team in the 70's and 80's.They displayed models at shows etc and the noise was unbelievable.I saw a trade tent emptied in 10 seconds when they started this beast.It could be heard over 10 miles away.You would have to have very understanding or deaf neighbours.
In the 80's we tried to start a home made jet engine.It did a sort of wet start fart,and we shot out of the garage before it did something else.
You can buy kits from Wren and assemble your own turbine.Then strap it to your bike or 1/5 scale F16.However model jet are very specialised and you really need a lot of experience flying models to be safe.
Hope this helps.
