Guys anyone have any idea how to recover booster stage and how to eject booster stage from main engine
Yes, how I do it, this one is 75mm airframe.
Interstage coupler contains timer & altimeter. Also used as nosecone for booster. Recovery gear is mounted to top of motor closure with eyebolt and to bottom of ISCoupler with eyebolt .
Coupler end fitting into sustainer contains a .5gram [1/2 gram] of BlackPowder for separation charge.
Timer is set to fire charge at motor burnout, so sustainer can coast free of booster weight. Sustainer lit from front by it's own altimeter/timer after delay of X seconds determined by thrust burn time/profile of of motor in booster.
Interstage coupler has ejection charge on back side fitting into booster for blowing off interstage/NC .....pulling out booster chute.
I use altimeter to fire this charge & give me altitude reading on booster. If you don't need/care about readings, another timer can be used to eject chute.
Yesterday flew a 4 grain motor with 1.5 second burn time in booster to a 2 grain sustainer motor. After running thrust curves determined best timer for sustainer firing setting to be: 3.8 seconds
Timer in Interstage for burnout or 1.5 sec
Booster fires 1.5sec ..........separate sustainer at burn-out...... coast for 2.3 sec fire sustainer. Coast determined by allowing sustainer to slow down to 575ft per second ,after separating from booster, then fire.
Flight functioned perfectly. Altitude was only 10,600. This was proof of concept for much larger motors. The booster is 75mm minimum diameter staging to another 75mm airframe with a 54mm motor mount.
Just trying to work out the Booster separation & staging timers.
Good luck on yours &hope this helps!
PS should mention: Interstage coupler has a vent band around it.[2in length of airframe, glued to coupler.] Coupler slides freely into booster so it can be used as nose cone for the booster. This vent band is same size as airframe Keeping coupler from sliding into booster airframe & is where holes for altimeter breathing and switches can be mounted.