Payload (tracker, altimeter) in a PML Bumblebee?

[4regt4]

The title pretty much sums it up. I'm starting on a PML Bumblebee, and I need to figure out a place to put a small altimeter and a Marco Polo. Yes, I know some people tie or tape a M.P. to the shock cord, but I've broke 2 antennas doing that, and I don't want to send another in for repair.

For those unfamiliar, the Bumblebee is quite short and there is only a few inches in the body forward of the CR. By design, the parachute is packed in a 3" tube that is mounted inside the nose cone. There is not a huge amount of spare room there either.

Normally, I either put the goodies in a 24mm tube permanently mounted in the nose cone with an Estes plastic screw on motor retainer to secure them, or if there is a proper payload bay, I velcro and zip tie them to a small board. There is room for neither in the Bumblebee. I suppose I could put a tube in the nose cone parachute bay, except I'm a bit paranoid about fouling the chute on deployment. A flat mount on the internal surface of the nose cone inner tube may work, but I don't see an easy way to retain the electronics w/o risk of them coming loose.

There might be room in the space between the MMT and body tube. But again I'm not sure how to retain things, and also if not done right it could compromise the integrity of the MMT assembly.

Ideas?

Hans.

 

[sharkbait]

G

The title pretty much sums it up. I'm starting on a PML Bumblebee, and I need to figure out a place to put a small altimeter and a Marco Polo. Yes, I know some people tie or tape a M.P. to the shock cord, but I've broke 2 antennas doing that, and I don't want to send another in for repair.

For those unfamiliar, the Bumblebee is quite short and there is only a few inches in the body forward of the CR. By design, the parachute is packed in a 3" tube that is mounted inside the nose cone. There is not a huge amount of spare room there either.

Normally, I either put the goodies in a 24mm tube permanently mounted in the nose cone with an Estes plastic screw on motor retainer to secure them, or if there is a proper payload bay, I velcro and zip tie them to a small board. There is room for neither in the Bumblebee. I suppose I could put a tube in the nose cone parachute bay, except I'm a bit paranoid about fouling the chute on deployment. A flat mount on the internal surface of the nose cone inner tube may work, but I don't see an easy way to retain the electronics w/o risk of them coming loose.

There might be room in the space between the MMT and body tube. But again I'm not sure how to retain things, and also if not done right it could compromise the integrity of the MMT assembly.

Ideas?

Hans.

Go old school and put a hatch door between two of the fins, you got a 38mm mount in a 4” body tube, plenty of space there

 

[4regt4]

G

Go old school and put a hatch door between two of the fins, you got a 38mm mount in a 4” body tube, plenty of space there

I kind of thought of that, but was unsure if the Quantum tube would have problems if it were cut in the side. I don't know enough about Q.T. I've heard it can be brittle. I was trying to think of a way to access that space through either of the centering rings. They are 1/4" thick, probably plenty strong that I could cut a chunk out. Not sure how to engineer that...

Hans.

 

[4regt4]

Woke up in the middle of the night. Trouble getting back to sleep, so I started thinking about this again. I came up with 2 possible solutions:

1. Cut a roughly 1" hole in the bottom C/R (enough for a Marco Polo and Pnut altimeter to slide through. Put a 24mm tube inside the fin can to contain the gadgets. The problem is securing everything. What I came up with is to use a centering ring that is a loose fit, and put it on the aft end after loading up the M.P. and altimeter - covering up the hole. This ring is held in place by the screw on motor retainer.

2. This one I like better: I *think* there is enough room up forward in the nose cone, above the parachute compartment. I could glue in a piece of all-thread in the tip of the nose cone and connect to it with the eye bolt via a coupling nut. This makes the parachute bay removable, leaving space to pack in the electronics up above.

Hans.

 

[Donnager]

If you've had trouble with "taped on" you can upgrade to a loose tube mount, with bulkheads to protect the internals. The "protector tube" can be clipped to the shock cord at both ends. Reinforce the small container tube well.

I've lost a few tracker pucks on ejection (found the tracker, but the rocket was somewhere else). Edit: when only taped.

 

[4regt4]

If you've had trouble with "taped on" you can upgrade to a loose tube mount, with bulkheads to protect the internals. The "protector tube" can be clipped to the shock cord at both ends. Reinforce the small container tube well.

I've lost a few tracker pucks on ejection (found the tracker, but the rocket was somewhere else). Edit: when only taped.

I'm afraid it would be a tight fit in this rocket. There is only a few inches in the body tube itself. The nose cone compartment is more like 8 inches. But a separate payload tube would be 1/3 of the diameter of the nose cone compartment, and it could foul the chute on deployment. May not, but it might. Not a chance I want to take. It would take a 1" payload tube about 5" (maybe 6") long to house both a Marco Polo and a Pnut altimeter. There is plenty of room in the fin can or above the nose cone compartment for both, if I can figure out a reasonable way to access and secure.

Hans.