Parachute Recovery for Booster Stage

I've got a two-stage BP model in mind with kind of a longish booster. I'm a little worried that, rather than tumble, the booster might just fall straight down, and I'd like to have a parachute in there.

I did see this thread, which looks like a pretty ingenious system, but I'm actually going to see about converting a single-stage kit into a two stager, and don't want to put on any external pods if I can help it.

I plan on using a long motor tube to funnel the gasses toward the sustainer motor. What I'm unsure of is where to pack the chute so it doesn't get charred (maybe next to the motor tube, just above a centering ring), and also how to ensure the chute actually comes out.

One idea I had was simply to put a bunch of holes in both booster centering rings, so that, as the booster falls away, the air passing through the rings would push the chute out. But I'm not sure how reliable that would be.

Another idea I had would be to loosely tape or attach the chute via a string or something to the sustainer, so that it would pull the chute out as it pulls away from the booster. But that seems as if it could make the sustainer veer off course. Perhaps an attachment where the motor would actually burn through the string, or something. Also, seems like maybe a bad idea, or at least something that could fail as often as it works.

[Edit] I should clarify this part. What I mean is a small bit of tape which would be meant to pull away from the booster. Not just a string permanently attached to the sustainer - obviously, that would be a bad idea, as it would drag the booster along with it.

Or rear ejection maybe? I've never built one of those, so I'm not entirely sure how they work. I'm not sure if the motor ejecting would also be there long enough to light the upper stage motor.

Anybody ever try this before? What system did you come up with? I'm not really set up to mess with any kind of loose BP pyro ejection charges (I live in an apartment), so I'm not sure how practical my idea is. Seems like there should be a workable solution, but I'm not sure what it is.

Thanks!

Hey Daniel,
I haven't done any booster designing but as I understand it, fin placement can ensure a CP/CG relationship that will result in a tumble. I know Jim Flis has worked up many booster designs that needed some tweaking in the prototype stage (those get launched off of Pad 9 to be as far from the crowd as is reasonable).

Instead of a chute for the booster, think about a streamer. 2" crepe paper in bright colors is available at party and craft stores and is flame resistant. It may work more reliably than a chute.

You can also pack the parachute in the bottom of the upper stage. This can be accomplished with varying degrees of sophistication. The most reliable is a spooler pod that wraps around the upper stage engine mount. Spool your parachute or streamer around it, then mount the second stage.

You might consider a rear ejection parachute.
Blows the MMT out, theathered to the booster air frame with the chute in between.
Chute can be packed around the MMT tube.
If that helps any.

KennB said:

Hey Daniel,
I haven't done any booster designing but as I understand it, fin placement can ensure a CP/CG relationship that will result in a tumble. I know Jim Flis has worked up many booster designs that needed some tweaking in the prototype stage (those get launched off of Pad 9 to be as far from the crowd as is reasonable).

Instead of a chute for the booster, think about a streamer. 2" crepe paper in bright colors is available at party and craft stores and is flame resistant. It may work more reliably than a chute.

Click to expand...

The rocket I'm hoping to adapt is the Estes STM-012.



With the forward and aft fins, it looks kind of sounding rocket-ish. I'm thinking I can turn the two sections (I think it comes in two parts) into two separate stages.

It's a long rocket, though, so I'm not sure it will be practical to gap stage. It might be too much of a gap. I'll have to look at it when it arrives. But if it looks like it might work, I may try it. The fins are TTW on both sections, so I couldn't move them, although I guess I could shorten the booster tube if the gap is too far, and to make the booster more tumbly. I'd like to see if I can keep the rocket looking the same, though. I'll have to measure the distance between the forward end of the booster tube and the sustainer motor.

I might try the spooling technique around the upper stage motor mount, if it looks like the gap is stageable. I hadn't thought of that. I can extend the motor tube all the way up so that it nearly touches the sustainer motor and do my vent holes somewhere near the top of the booster motor tube. Then I can pack the chute or streamer and maybe line it with a bit of wadding for safety.

They're super cheap right now, so I ordered three of them. I figure I can build one stock, and have two others to play around with.

what size diameter airframe are you planning on using. If large enough you can mount an extra motor tube in the sustainer stage and cap it and use this as storage for your chute. As the stages separate the chute comes out and opens. Of course you would also have the same design in the booster to store the shroud lines etc. On the same line you can pack a streamer in the upper stage so when the stages separate the streamers comes out of the upper section and as it falls pulls the chute out.

AfterBurners said:

what size diameter airframe are you planning on using. If large enough you can mount an extra motor tube in the sustainer stage and cap it and use this as storage for your chute. As the stages separate the chute comes out and opens. Of course you would also have the same design in the booster to store the shroud lines etc. On the same line you can pack a streamer in the upper stage so when the stages separate the streamers comes out of the upper section and as it falls pulls the chute out.

Click to expand...

Another great idea. It's a BT-60. Motor tube is 24mm. Probably room in there on the side for a bit of BT-20 or BT-5.

Either way, sounds like packing the booster recovery system into the sustainer is the way to go. Much like the thread in the original post, but on the inside of the rocket.

Seems so simple now. I wish I'd thought of it.

I've built a dual D12 pod augmented 29mm E2X booster two-stage Majestic, but haven't launched it yet. Parachute recovery is obviously required because the 29mm E2X booster is already massive enough and descends fast enough to probably put minor dents in a car.

Only the pod nose cones extend beyond the length of the E2X stage to hopefully reduce the odds of the pod nose cones being knocked off by contact with the upper stage due to booster yaw at separation. The coupler length spaces them from the Majestic before any major yaw can take place. Each pod nose cone is firmly friction fitted into its pod in the hopes of avoiding nose cone separation from the pod due to centrifugal force at separation and during booster tumbling.

Because of the short length of the pods required to avoid any more than the pod nose cones extending above the booster body, the elastic shock cords are stowed within each plastic nose cone. The shock cord attachment point is at the booster side of each pod in the hopes of maximizing booster tilt for the second parachute ejection event spaced in time by D12s with different delay times.

Both shock cords are the same length since, if this even works, I'd like a nifty looking pair of 15" plastic Estes 'chutes during the descent. If the whole concept doesn't prove deficient due to some factor (like booster tumbling snagging the first shock cord), but is found flawed due to both shock cords being the same length, I'll just lengthen one of them.

Don't know if this would work or not, but perhaps have the sustainer attached to a piston-like assembly that separates once the tube is pressurized enough (don't ask me how to do this, I'm just kicking out ideas...) wrapped around the piston would be your booster's chute. I'm thinking of something like the rear ejecting Estes Sizzler (2127). The big problem I can see with it would be how to prevent the ejection charge of the booster from pressurizing the piston and popping the sustainer off w/o getting the piston/chute to deploy.