Booster stage recovery

Guys anyone have any idea how to recover booster stage and how to eject booster stage from main engine

Too broad a question. Are you using black powder motors taped together with motor-to-motor ignition, or composite motors with a staging timer? There's no one answer.

Let me be clear I am using a r candy propellant (kno3 and sugar)
I am planing to ignite the stage by timer or mercury switch because the method you are talking about is less reliable because r candy propellant motor takes time to build pressure so to ignite the motor with ignite will produce more pressure so won't take time build pressure

The folks that post here mostly burn commercial motors and follow the NAR and/or TRA safety codes. You probably won't get any responses. Sorry.

Don't you have any idea have do composite staging

2 function timer, one for the ignition of the upper stage that happens first, and then one for the ejection of a recovery device for the booster.

If the upper motor ignites it will separate and fly off and the booster will continue coasting for a while before the ejection charge. If the upper motor doesn't ignite, the model stays together and the booster ejection charge fires bringing the whole thing down under the booster's parachute.

All the electronics for that should be housed in the booster.

Sounds simple enough, and if you look into composite powered multi-stage projects, you will find the information you need.

kj

Okay first thanks for info but I am concerned more with that how to seprate the two stage what mechanism should be used guys

The upper stage motor will do the separation for you when it fires, there is no mechanism required.

Why do you think it has to be more complicated?

kj

I would not suggest using a timer for staging. I have not personally used one but I know that the timer has no way of mitigating the staging if something goes wrong (ex: Cato, unstable flight, early deployment, ect.). My suggestion would be to use a Raven 3 to do your staging, it can also do stage separation since it has four outputs. It's also small enough to fit in just about any rocket (1.75" x 0.8").

The Raven's programming software allows you to set it up to not fire the output that lights your sustainer if something goes wrong. For example, you can have it fire the igniter if it reaches a specific altitude in a specific amount of time. That would provide a much safer flight profile than a simple timer. I have personally used this method in my own two stage flight (38mm J motor staged to 38mm J motor) without issues.

As for an ignition source, the same igniter you use to light your booster motor should suffice, but only if the motor comes up to pressure fast. If your normal ignitions take a couple of seconds to fully come up to pressure, try a more powerful ignition source to ensure the motor comes up to pressure quickly. Another good practice for larger motors (54mm and above) is to tape your igniter to a wooden dowel so it stays supported in the motor during the booster motor burn.

For separating the stages I would suggest a second altimeter in the interstage coupler. Use a black powder charge to separate. The same altimeter can also control the deployment of the parachutes for the booster.

The OP (see other thread) is in an area where he cannot get an altimeter shipped, and already has an N3555 timer. He is looking for help with wiring and operation for what he already has.

It would probably help, in general, if the OP opened a single thread to discuss his project in one place instead of multiple unconnected threads for each topic he wants to discuss. I'm sure it would help people have a better idea of what he's planning to build, what he's looking for help with, and what comments/suggestions have already been covered.

Bat-mite said:

The OP (see other thread) is in an area where he cannot get an altimeter shipped, and already has an N3555 timer. He is looking for help with wiring and operation for what he already has.

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Ah I didn't know. Well since I would never suggest a timer for staging, I'm out of ideas.

chand said:

Guys anyone have any idea how to recover booster stage and how to eject booster stage from main engine

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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.

blackjack2564 said:

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.

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I use CJs setup and like it a lot. One thing I have learned the hard way about using altimeter vent holes on the vent band of the IScoupler is that there are pressure transients at stage separation that can fool the altimeter and cause early booster recovery deployment. I think they are from having the vent holes up so close to the turbulent airflow once the IScoupler becomes the nosecone for the booster. The problem gets worse with higher impulse booster motors that get the stack moving faster at separation. I suspect the answer is to move the altimeter vent holes aft onto the airframe where the airflow is less turbulent. That means having to line up the holes with holes on the AV bay of the IS coupler, but that is not a big problem since I also shear pin the IScoupler to the booster.

WoShuGui said:

I suspect the answer is to move the altimeter vent holes aft onto the airframe where the airflow is less turbulent. That means having to line up the holes with holes on the AV bay of the IS coupler, but that is not a big problem since I also shear pin the IScoupler to the booster.

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I like that idea. I'm currently rebuilding the ISCouoler on my darkstar Jr. Going to have to steal that idea, sorry.